diff options
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/Kconfig | 8 | ||||
| -rw-r--r-- | fs/notify/Makefile | 7 | ||||
| -rw-r--r-- | fs/notify/dnotify/Kconfig | 12 | ||||
| -rw-r--r-- | fs/notify/dnotify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/dnotify/dnotify.c | 392 | ||||
| -rw-r--r-- | fs/notify/fanotify/Kconfig | 27 | ||||
| -rw-r--r-- | fs/notify/fanotify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/fanotify/fanotify.c | 815 | ||||
| -rw-r--r-- | fs/notify/fanotify/fanotify.h | 286 | ||||
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 1349 | ||||
| -rw-r--r-- | fs/notify/fdinfo.c | 149 | ||||
| -rw-r--r-- | fs/notify/fdinfo.h | 28 | ||||
| -rw-r--r-- | fs/notify/fsnotify.c | 572 | ||||
| -rw-r--r-- | fs/notify/fsnotify.h | 70 | ||||
| -rw-r--r-- | fs/notify/group.c | 149 | ||||
| -rw-r--r-- | fs/notify/inotify/Kconfig | 17 | ||||
| -rw-r--r-- | fs/notify/inotify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify.h | 62 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify_fsnotify.c | 207 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify_user.c | 830 | ||||
| -rw-r--r-- | fs/notify/mark.c | 849 | ||||
| -rw-r--r-- | fs/notify/notification.c | 189 |
22 files changed, 6024 insertions, 0 deletions
diff --git a/fs/notify/Kconfig b/fs/notify/Kconfig new file mode 100644 index 000000000..c020d26ba --- /dev/null +++ b/fs/notify/Kconfig @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0-only +config FSNOTIFY + def_bool n + select SRCU + +source "fs/notify/dnotify/Kconfig" +source "fs/notify/inotify/Kconfig" +source "fs/notify/fanotify/Kconfig" diff --git a/fs/notify/Makefile b/fs/notify/Makefile new file mode 100644 index 000000000..63a4b8828 --- /dev/null +++ b/fs/notify/Makefile @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o mark.o \ + fdinfo.o + +obj-y += dnotify/ +obj-y += inotify/ +obj-y += fanotify/ diff --git a/fs/notify/dnotify/Kconfig b/fs/notify/dnotify/Kconfig new file mode 100644 index 000000000..3df7def17 --- /dev/null +++ b/fs/notify/dnotify/Kconfig @@ -0,0 +1,12 @@ +# SPDX-License-Identifier: GPL-2.0-only +config DNOTIFY + bool "Dnotify support" + select FSNOTIFY + default y + help + Dnotify is a directory-based per-fd file change notification system + that uses signals to communicate events to user-space. There exist + superior alternatives, but some applications may still rely on + dnotify. + + If unsure, say Y. diff --git a/fs/notify/dnotify/Makefile b/fs/notify/dnotify/Makefile new file mode 100644 index 000000000..121b4dd6b --- /dev/null +++ b/fs/notify/dnotify/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_DNOTIFY) += dnotify.o diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c new file mode 100644 index 000000000..e45ca6ecb --- /dev/null +++ b/fs/notify/dnotify/dnotify.c @@ -0,0 +1,392 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Directory notifications for Linux. + * + * Copyright (C) 2000,2001,2002 Stephen Rothwell + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * dnotify was largly rewritten to use the new fsnotify infrastructure + */ +#include <linux/fs.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/sched/signal.h> +#include <linux/dnotify.h> +#include <linux/init.h> +#include <linux/security.h> +#include <linux/spinlock.h> +#include <linux/slab.h> +#include <linux/fdtable.h> +#include <linux/fsnotify_backend.h> + +int dir_notify_enable __read_mostly = 1; + +static struct kmem_cache *dnotify_struct_cache __read_mostly; +static struct kmem_cache *dnotify_mark_cache __read_mostly; +static struct fsnotify_group *dnotify_group __read_mostly; + +/* + * dnotify will attach one of these to each inode (i_fsnotify_marks) which + * is being watched by dnotify. If multiple userspace applications are watching + * the same directory with dnotify their information is chained in dn + */ +struct dnotify_mark { + struct fsnotify_mark fsn_mark; + struct dnotify_struct *dn; +}; + +/* + * When a process starts or stops watching an inode the set of events which + * dnotify cares about for that inode may change. This function runs the + * list of everything receiving dnotify events about this directory and calculates + * the set of all those events. After it updates what dnotify is interested in + * it calls the fsnotify function so it can update the set of all events relevant + * to this inode. + */ +static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) +{ + __u32 new_mask = 0; + struct dnotify_struct *dn; + struct dnotify_mark *dn_mark = container_of(fsn_mark, + struct dnotify_mark, + fsn_mark); + + assert_spin_locked(&fsn_mark->lock); + + for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next) + new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT); + if (fsn_mark->mask == new_mask) + return; + fsn_mark->mask = new_mask; + + fsnotify_recalc_mask(fsn_mark->connector); +} + +/* + * Mains fsnotify call where events are delivered to dnotify. + * Find the dnotify mark on the relevant inode, run the list of dnotify structs + * on that mark and determine which of them has expressed interest in receiving + * events of this type. When found send the correct process and signal and + * destroy the dnotify struct if it was not registered to receive multiple + * events. + */ +static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask, + struct inode *inode, struct inode *dir, + const struct qstr *name, u32 cookie) +{ + struct dnotify_mark *dn_mark; + struct dnotify_struct *dn; + struct dnotify_struct **prev; + struct fown_struct *fown; + __u32 test_mask = mask & ~FS_EVENT_ON_CHILD; + + /* not a dir, dnotify doesn't care */ + if (!dir && !(mask & FS_ISDIR)) + return 0; + + dn_mark = container_of(inode_mark, struct dnotify_mark, fsn_mark); + + spin_lock(&inode_mark->lock); + prev = &dn_mark->dn; + while ((dn = *prev) != NULL) { + if ((dn->dn_mask & test_mask) == 0) { + prev = &dn->dn_next; + continue; + } + fown = &dn->dn_filp->f_owner; + send_sigio(fown, dn->dn_fd, POLL_MSG); + if (dn->dn_mask & FS_DN_MULTISHOT) + prev = &dn->dn_next; + else { + *prev = dn->dn_next; + kmem_cache_free(dnotify_struct_cache, dn); + dnotify_recalc_inode_mask(inode_mark); + } + } + + spin_unlock(&inode_mark->lock); + + return 0; +} + +static void dnotify_free_mark(struct fsnotify_mark *fsn_mark) +{ + struct dnotify_mark *dn_mark = container_of(fsn_mark, + struct dnotify_mark, + fsn_mark); + + BUG_ON(dn_mark->dn); + + kmem_cache_free(dnotify_mark_cache, dn_mark); +} + +static const struct fsnotify_ops dnotify_fsnotify_ops = { + .handle_inode_event = dnotify_handle_event, + .free_mark = dnotify_free_mark, +}; + +/* + * Called every time a file is closed. Looks first for a dnotify mark on the + * inode. If one is found run all of the ->dn structures attached to that + * mark for one relevant to this process closing the file and remove that + * dnotify_struct. If that was the last dnotify_struct also remove the + * fsnotify_mark. + */ +void dnotify_flush(struct file *filp, fl_owner_t id) +{ + struct fsnotify_mark *fsn_mark; + struct dnotify_mark *dn_mark; + struct dnotify_struct *dn; + struct dnotify_struct **prev; + struct inode *inode; + bool free = false; + + inode = file_inode(filp); + if (!S_ISDIR(inode->i_mode)) + return; + + fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, dnotify_group); + if (!fsn_mark) + return; + dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); + + mutex_lock(&dnotify_group->mark_mutex); + + spin_lock(&fsn_mark->lock); + prev = &dn_mark->dn; + while ((dn = *prev) != NULL) { + if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { + *prev = dn->dn_next; + kmem_cache_free(dnotify_struct_cache, dn); + dnotify_recalc_inode_mask(fsn_mark); + break; + } + prev = &dn->dn_next; + } + + spin_unlock(&fsn_mark->lock); + + /* nothing else could have found us thanks to the dnotify_groups + mark_mutex */ + if (dn_mark->dn == NULL) { + fsnotify_detach_mark(fsn_mark); + free = true; + } + + mutex_unlock(&dnotify_group->mark_mutex); + + if (free) + fsnotify_free_mark(fsn_mark); + fsnotify_put_mark(fsn_mark); +} + +/* this conversion is done only at watch creation */ +static __u32 convert_arg(unsigned long arg) +{ + __u32 new_mask = FS_EVENT_ON_CHILD; + + if (arg & DN_MULTISHOT) + new_mask |= FS_DN_MULTISHOT; + if (arg & DN_DELETE) + new_mask |= (FS_DELETE | FS_MOVED_FROM); + if (arg & DN_MODIFY) + new_mask |= FS_MODIFY; + if (arg & DN_ACCESS) + new_mask |= FS_ACCESS; + if (arg & DN_ATTRIB) + new_mask |= FS_ATTRIB; + if (arg & DN_RENAME) + new_mask |= FS_DN_RENAME; + if (arg & DN_CREATE) + new_mask |= (FS_CREATE | FS_MOVED_TO); + + return new_mask; +} + +/* + * If multiple processes watch the same inode with dnotify there is only one + * dnotify mark in inode->i_fsnotify_marks but we chain a dnotify_struct + * onto that mark. This function either attaches the new dnotify_struct onto + * that list, or it |= the mask onto an existing dnofiy_struct. + */ +static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark *dn_mark, + fl_owner_t id, int fd, struct file *filp, __u32 mask) +{ + struct dnotify_struct *odn; + + odn = dn_mark->dn; + while (odn != NULL) { + /* adding more events to existing dnofiy_struct? */ + if ((odn->dn_owner == id) && (odn->dn_filp == filp)) { + odn->dn_fd = fd; + odn->dn_mask |= mask; + return -EEXIST; + } + odn = odn->dn_next; + } + + dn->dn_mask = mask; + dn->dn_fd = fd; + dn->dn_filp = filp; + dn->dn_owner = id; + dn->dn_next = dn_mark->dn; + dn_mark->dn = dn; + + return 0; +} + +/* + * When a process calls fcntl to attach a dnotify watch to a directory it ends + * up here. Allocate both a mark for fsnotify to add and a dnotify_struct to be + * attached to the fsnotify_mark. + */ +int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) +{ + struct dnotify_mark *new_dn_mark, *dn_mark; + struct fsnotify_mark *new_fsn_mark, *fsn_mark; + struct dnotify_struct *dn; + struct inode *inode; + fl_owner_t id = current->files; + struct file *f; + int destroy = 0, error = 0; + __u32 mask; + + /* we use these to tell if we need to kfree */ + new_fsn_mark = NULL; + dn = NULL; + + if (!dir_notify_enable) { + error = -EINVAL; + goto out_err; + } + + /* a 0 mask means we are explicitly removing the watch */ + if ((arg & ~DN_MULTISHOT) == 0) { + dnotify_flush(filp, id); + error = 0; + goto out_err; + } + + /* dnotify only works on directories */ + inode = file_inode(filp); + if (!S_ISDIR(inode->i_mode)) { + error = -ENOTDIR; + goto out_err; + } + + /* + * convert the userspace DN_* "arg" to the internal FS_* + * defined in fsnotify + */ + mask = convert_arg(arg); + + error = security_path_notify(&filp->f_path, mask, + FSNOTIFY_OBJ_TYPE_INODE); + if (error) + goto out_err; + + /* expect most fcntl to add new rather than augment old */ + dn = kmem_cache_alloc(dnotify_struct_cache, GFP_KERNEL); + if (!dn) { + error = -ENOMEM; + goto out_err; + } + + /* new fsnotify mark, we expect most fcntl calls to add a new mark */ + new_dn_mark = kmem_cache_alloc(dnotify_mark_cache, GFP_KERNEL); + if (!new_dn_mark) { + error = -ENOMEM; + goto out_err; + } + + /* set up the new_fsn_mark and new_dn_mark */ + new_fsn_mark = &new_dn_mark->fsn_mark; + fsnotify_init_mark(new_fsn_mark, dnotify_group); + new_fsn_mark->mask = mask; + new_dn_mark->dn = NULL; + + /* this is needed to prevent the fcntl/close race described below */ + mutex_lock(&dnotify_group->mark_mutex); + + /* add the new_fsn_mark or find an old one. */ + fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, dnotify_group); + if (fsn_mark) { + dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); + spin_lock(&fsn_mark->lock); + } else { + error = fsnotify_add_inode_mark_locked(new_fsn_mark, inode, 0); + if (error) { + mutex_unlock(&dnotify_group->mark_mutex); + goto out_err; + } + spin_lock(&new_fsn_mark->lock); + fsn_mark = new_fsn_mark; + dn_mark = new_dn_mark; + /* we used new_fsn_mark, so don't free it */ + new_fsn_mark = NULL; + } + + rcu_read_lock(); + f = fcheck(fd); + rcu_read_unlock(); + + /* if (f != filp) means that we lost a race and another task/thread + * actually closed the fd we are still playing with before we grabbed + * the dnotify_groups mark_mutex and fsn_mark->lock. Since closing the + * fd is the only time we clean up the marks we need to get our mark + * off the list. */ + if (f != filp) { + /* if we added ourselves, shoot ourselves, it's possible that + * the flush actually did shoot this fsn_mark. That's fine too + * since multiple calls to destroy_mark is perfectly safe, if + * we found a dn_mark already attached to the inode, just sod + * off silently as the flush at close time dealt with it. + */ + if (dn_mark == new_dn_mark) + destroy = 1; + error = 0; + goto out; + } + + __f_setown(filp, task_pid(current), PIDTYPE_TGID, 0); + + error = attach_dn(dn, dn_mark, id, fd, filp, mask); + /* !error means that we attached the dn to the dn_mark, so don't free it */ + if (!error) + dn = NULL; + /* -EEXIST means that we didn't add this new dn and used an old one. + * that isn't an error (and the unused dn should be freed) */ + else if (error == -EEXIST) + error = 0; + + dnotify_recalc_inode_mask(fsn_mark); +out: + spin_unlock(&fsn_mark->lock); + + if (destroy) + fsnotify_detach_mark(fsn_mark); + mutex_unlock(&dnotify_group->mark_mutex); + if (destroy) + fsnotify_free_mark(fsn_mark); + fsnotify_put_mark(fsn_mark); +out_err: + if (new_fsn_mark) + fsnotify_put_mark(new_fsn_mark); + if (dn) + kmem_cache_free(dnotify_struct_cache, dn); + return error; +} + +static int __init dnotify_init(void) +{ + dnotify_struct_cache = KMEM_CACHE(dnotify_struct, + SLAB_PANIC|SLAB_ACCOUNT); + dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC|SLAB_ACCOUNT); + + dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops); + if (IS_ERR(dnotify_group)) + panic("unable to allocate fsnotify group for dnotify\n"); + return 0; +} + +module_init(dnotify_init) diff --git a/fs/notify/fanotify/Kconfig b/fs/notify/fanotify/Kconfig new file mode 100644 index 000000000..a511f9d86 --- /dev/null +++ b/fs/notify/fanotify/Kconfig @@ -0,0 +1,27 @@ +# SPDX-License-Identifier: GPL-2.0-only +config FANOTIFY + bool "Filesystem wide access notification" + select FSNOTIFY + select EXPORTFS + default n + help + Say Y here to enable fanotify support. fanotify is a file access + notification system which differs from inotify in that it sends + an open file descriptor to the userspace listener along with + the event. + + If unsure, say Y. + +config FANOTIFY_ACCESS_PERMISSIONS + bool "fanotify permissions checking" + depends on FANOTIFY + depends on SECURITY + default n + help + Say Y here is you want fanotify listeners to be able to make permissions + decisions concerning filesystem events. This is used by some fanotify + listeners which need to scan files before allowing the system access to + use those files. This is used by some anti-malware vendors and by some + hierarchical storage management systems. + + If unsure, say N. diff --git a/fs/notify/fanotify/Makefile b/fs/notify/fanotify/Makefile new file mode 100644 index 000000000..25ef22291 --- /dev/null +++ b/fs/notify/fanotify/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_FANOTIFY) += fanotify.o fanotify_user.o diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c new file mode 100644 index 000000000..c3af99e94 --- /dev/null +++ b/fs/notify/fanotify/fanotify.c @@ -0,0 +1,815 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/fanotify.h> +#include <linux/fdtable.h> +#include <linux/fsnotify_backend.h> +#include <linux/init.h> +#include <linux/jiffies.h> +#include <linux/kernel.h> /* UINT_MAX */ +#include <linux/mount.h> +#include <linux/sched.h> +#include <linux/sched/user.h> +#include <linux/sched/signal.h> +#include <linux/types.h> +#include <linux/wait.h> +#include <linux/audit.h> +#include <linux/sched/mm.h> +#include <linux/statfs.h> + +#include "fanotify.h" + +static bool fanotify_path_equal(struct path *p1, struct path *p2) +{ + return p1->mnt == p2->mnt && p1->dentry == p2->dentry; +} + +static inline bool fanotify_fsid_equal(__kernel_fsid_t *fsid1, + __kernel_fsid_t *fsid2) +{ + return fsid1->val[0] == fsid2->val[0] && fsid1->val[1] == fsid2->val[1]; +} + +static bool fanotify_fh_equal(struct fanotify_fh *fh1, + struct fanotify_fh *fh2) +{ + if (fh1->type != fh2->type || fh1->len != fh2->len) + return false; + + return !fh1->len || + !memcmp(fanotify_fh_buf(fh1), fanotify_fh_buf(fh2), fh1->len); +} + +static bool fanotify_fid_event_equal(struct fanotify_fid_event *ffe1, + struct fanotify_fid_event *ffe2) +{ + /* Do not merge fid events without object fh */ + if (!ffe1->object_fh.len) + return false; + + return fanotify_fsid_equal(&ffe1->fsid, &ffe2->fsid) && + fanotify_fh_equal(&ffe1->object_fh, &ffe2->object_fh); +} + +static bool fanotify_info_equal(struct fanotify_info *info1, + struct fanotify_info *info2) +{ + if (info1->dir_fh_totlen != info2->dir_fh_totlen || + info1->file_fh_totlen != info2->file_fh_totlen || + info1->name_len != info2->name_len) + return false; + + if (info1->dir_fh_totlen && + !fanotify_fh_equal(fanotify_info_dir_fh(info1), + fanotify_info_dir_fh(info2))) + return false; + + if (info1->file_fh_totlen && + !fanotify_fh_equal(fanotify_info_file_fh(info1), + fanotify_info_file_fh(info2))) + return false; + + return !info1->name_len || + !memcmp(fanotify_info_name(info1), fanotify_info_name(info2), + info1->name_len); +} + +static bool fanotify_name_event_equal(struct fanotify_name_event *fne1, + struct fanotify_name_event *fne2) +{ + struct fanotify_info *info1 = &fne1->info; + struct fanotify_info *info2 = &fne2->info; + + /* Do not merge name events without dir fh */ + if (!info1->dir_fh_totlen) + return false; + + if (!fanotify_fsid_equal(&fne1->fsid, &fne2->fsid)) + return false; + + return fanotify_info_equal(info1, info2); +} + +static bool fanotify_should_merge(struct fsnotify_event *old_fsn, + struct fsnotify_event *new_fsn) +{ + struct fanotify_event *old, *new; + + pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn); + old = FANOTIFY_E(old_fsn); + new = FANOTIFY_E(new_fsn); + + if (old_fsn->objectid != new_fsn->objectid || + old->type != new->type || old->pid != new->pid) + return false; + + /* + * We want to merge many dirent events in the same dir (i.e. + * creates/unlinks/renames), but we do not want to merge dirent + * events referring to subdirs with dirent events referring to + * non subdirs, otherwise, user won't be able to tell from a + * mask FAN_CREATE|FAN_DELETE|FAN_ONDIR if it describes mkdir+ + * unlink pair or rmdir+create pair of events. + */ + if ((old->mask & FS_ISDIR) != (new->mask & FS_ISDIR)) + return false; + + switch (old->type) { + case FANOTIFY_EVENT_TYPE_PATH: + return fanotify_path_equal(fanotify_event_path(old), + fanotify_event_path(new)); + case FANOTIFY_EVENT_TYPE_FID: + return fanotify_fid_event_equal(FANOTIFY_FE(old), + FANOTIFY_FE(new)); + case FANOTIFY_EVENT_TYPE_FID_NAME: + return fanotify_name_event_equal(FANOTIFY_NE(old), + FANOTIFY_NE(new)); + default: + WARN_ON_ONCE(1); + } + + return false; +} + +/* Limit event merges to limit CPU overhead per event */ +#define FANOTIFY_MAX_MERGE_EVENTS 128 + +/* and the list better be locked by something too! */ +static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) +{ + struct fsnotify_event *test_event; + struct fanotify_event *new; + int i = 0; + + pr_debug("%s: list=%p event=%p\n", __func__, list, event); + new = FANOTIFY_E(event); + + /* + * Don't merge a permission event with any other event so that we know + * the event structure we have created in fanotify_handle_event() is the + * one we should check for permission response. + */ + if (fanotify_is_perm_event(new->mask)) + return 0; + + list_for_each_entry_reverse(test_event, list, list) { + if (++i > FANOTIFY_MAX_MERGE_EVENTS) + break; + if (fanotify_should_merge(test_event, event)) { + FANOTIFY_E(test_event)->mask |= new->mask; + return 1; + } + } + + return 0; +} + +/* + * Wait for response to permission event. The function also takes care of + * freeing the permission event (or offloads that in case the wait is canceled + * by a signal). The function returns 0 in case access got allowed by userspace, + * -EPERM in case userspace disallowed the access, and -ERESTARTSYS in case + * the wait got interrupted by a signal. + */ +static int fanotify_get_response(struct fsnotify_group *group, + struct fanotify_perm_event *event, + struct fsnotify_iter_info *iter_info) +{ + int ret; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + ret = wait_event_killable(group->fanotify_data.access_waitq, + event->state == FAN_EVENT_ANSWERED); + /* Signal pending? */ + if (ret < 0) { + spin_lock(&group->notification_lock); + /* Event reported to userspace and no answer yet? */ + if (event->state == FAN_EVENT_REPORTED) { + /* Event will get freed once userspace answers to it */ + event->state = FAN_EVENT_CANCELED; + spin_unlock(&group->notification_lock); + return ret; + } + /* Event not yet reported? Just remove it. */ + if (event->state == FAN_EVENT_INIT) + fsnotify_remove_queued_event(group, &event->fae.fse); + /* + * Event may be also answered in case signal delivery raced + * with wakeup. In that case we have nothing to do besides + * freeing the event and reporting error. + */ + spin_unlock(&group->notification_lock); + goto out; + } + + /* userspace responded, convert to something usable */ + switch (event->response & ~FAN_AUDIT) { + case FAN_ALLOW: + ret = 0; + break; + case FAN_DENY: + default: + ret = -EPERM; + } + + /* Check if the response should be audited */ + if (event->response & FAN_AUDIT) + audit_fanotify(event->response & ~FAN_AUDIT); + + pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, + group, event, ret); +out: + fsnotify_destroy_event(group, &event->fae.fse); + + return ret; +} + +/* + * This function returns a mask for an event that only contains the flags + * that have been specifically requested by the user. Flags that may have + * been included within the event mask, but have not been explicitly + * requested by the user, will not be present in the returned mask. + */ +static u32 fanotify_group_event_mask(struct fsnotify_group *group, + struct fsnotify_iter_info *iter_info, + u32 event_mask, const void *data, + int data_type, struct inode *dir) +{ + __u32 marks_mask = 0, marks_ignored_mask = 0; + __u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS | + FANOTIFY_EVENT_FLAGS; + const struct path *path = fsnotify_data_path(data, data_type); + unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + struct fsnotify_mark *mark; + int type; + + pr_debug("%s: report_mask=%x mask=%x data=%p data_type=%d\n", + __func__, iter_info->report_mask, event_mask, data, data_type); + + if (!fid_mode) { + /* Do we have path to open a file descriptor? */ + if (!path) + return 0; + /* Path type events are only relevant for files and dirs */ + if (!d_is_reg(path->dentry) && !d_can_lookup(path->dentry)) + return 0; + } else if (!(fid_mode & FAN_REPORT_FID)) { + /* Do we have a directory inode to report? */ + if (!dir && !(event_mask & FS_ISDIR)) + return 0; + } + + fsnotify_foreach_obj_type(type) { + if (!fsnotify_iter_should_report_type(iter_info, type)) + continue; + mark = iter_info->marks[type]; + + /* Apply ignore mask regardless of ISDIR and ON_CHILD flags */ + marks_ignored_mask |= mark->ignored_mask; + + /* + * If the event is on dir and this mark doesn't care about + * events on dir, don't send it! + */ + if (event_mask & FS_ISDIR && !(mark->mask & FS_ISDIR)) + continue; + + /* + * If the event is on a child and this mark is on a parent not + * watching children, don't send it! + */ + if (type == FSNOTIFY_OBJ_TYPE_PARENT && + !(mark->mask & FS_EVENT_ON_CHILD)) + continue; + + marks_mask |= mark->mask; + } + + test_mask = event_mask & marks_mask & ~marks_ignored_mask; + + /* + * For dirent modification events (create/delete/move) that do not carry + * the child entry name information, we report FAN_ONDIR for mkdir/rmdir + * so user can differentiate them from creat/unlink. + * + * For backward compatibility and consistency, do not report FAN_ONDIR + * to user in legacy fanotify mode (reporting fd) and report FAN_ONDIR + * to user in fid mode for all event types. + * + * We never report FAN_EVENT_ON_CHILD to user, but we do pass it in to + * fanotify_alloc_event() when group is reporting fid as indication + * that event happened on child. + */ + if (fid_mode) { + /* Do not report event flags without any event */ + if (!(test_mask & ~FANOTIFY_EVENT_FLAGS)) + return 0; + } else { + user_mask &= ~FANOTIFY_EVENT_FLAGS; + } + + return test_mask & user_mask; +} + +/* + * Check size needed to encode fanotify_fh. + * + * Return size of encoded fh without fanotify_fh header. + * Return 0 on failure to encode. + */ +static int fanotify_encode_fh_len(struct inode *inode) +{ + int dwords = 0; + + if (!inode) + return 0; + + exportfs_encode_inode_fh(inode, NULL, &dwords, NULL); + + return dwords << 2; +} + +/* + * Encode fanotify_fh. + * + * Return total size of encoded fh including fanotify_fh header. + * Return 0 on failure to encode. + */ +static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode, + unsigned int fh_len, gfp_t gfp) +{ + int dwords, type = 0; + char *ext_buf = NULL; + void *buf = fh->buf; + int err; + + fh->type = FILEID_ROOT; + fh->len = 0; + fh->flags = 0; + if (!inode) + return 0; + + /* + * !gpf means preallocated variable size fh, but fh_len could + * be zero in that case if encoding fh len failed. + */ + err = -ENOENT; + if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4)) + goto out_err; + + /* No external buffer in a variable size allocated fh */ + if (gfp && fh_len > FANOTIFY_INLINE_FH_LEN) { + /* Treat failure to allocate fh as failure to encode fh */ + err = -ENOMEM; + ext_buf = kmalloc(fh_len, gfp); + if (!ext_buf) + goto out_err; + + *fanotify_fh_ext_buf_ptr(fh) = ext_buf; + buf = ext_buf; + fh->flags |= FANOTIFY_FH_FLAG_EXT_BUF; + } + + dwords = fh_len >> 2; + type = exportfs_encode_inode_fh(inode, buf, &dwords, NULL); + err = -EINVAL; + if (!type || type == FILEID_INVALID || fh_len != dwords << 2) + goto out_err; + + fh->type = type; + fh->len = fh_len; + + return FANOTIFY_FH_HDR_LEN + fh_len; + +out_err: + pr_warn_ratelimited("fanotify: failed to encode fid (type=%d, len=%d, err=%i)\n", + type, fh_len, err); + kfree(ext_buf); + *fanotify_fh_ext_buf_ptr(fh) = NULL; + /* Report the event without a file identifier on encode error */ + fh->type = FILEID_INVALID; + fh->len = 0; + return 0; +} + +/* + * The inode to use as identifier when reporting fid depends on the event. + * Report the modified directory inode on dirent modification events. + * Report the "victim" inode otherwise. + * For example: + * FS_ATTRIB reports the child inode even if reported on a watched parent. + * FS_CREATE reports the modified dir inode and not the created inode. + */ +static struct inode *fanotify_fid_inode(u32 event_mask, const void *data, + int data_type, struct inode *dir) +{ + if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS) + return dir; + + return fsnotify_data_inode(data, data_type); +} + +/* + * The inode to use as identifier when reporting dir fid depends on the event. + * Report the modified directory inode on dirent modification events. + * Report the "victim" inode if "victim" is a directory. + * Report the parent inode if "victim" is not a directory and event is + * reported to parent. + * Otherwise, do not report dir fid. + */ +static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data, + int data_type, struct inode *dir) +{ + struct inode *inode = fsnotify_data_inode(data, data_type); + + if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS) + return dir; + + if (S_ISDIR(inode->i_mode)) + return inode; + + return dir; +} + +static struct fanotify_event *fanotify_alloc_path_event(const struct path *path, + gfp_t gfp) +{ + struct fanotify_path_event *pevent; + + pevent = kmem_cache_alloc(fanotify_path_event_cachep, gfp); + if (!pevent) + return NULL; + + pevent->fae.type = FANOTIFY_EVENT_TYPE_PATH; + pevent->path = *path; + path_get(path); + + return &pevent->fae; +} + +static struct fanotify_event *fanotify_alloc_perm_event(const struct path *path, + gfp_t gfp) +{ + struct fanotify_perm_event *pevent; + + pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp); + if (!pevent) + return NULL; + + pevent->fae.type = FANOTIFY_EVENT_TYPE_PATH_PERM; + pevent->response = 0; + pevent->state = FAN_EVENT_INIT; + pevent->path = *path; + path_get(path); + + return &pevent->fae; +} + +static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id, + __kernel_fsid_t *fsid, + gfp_t gfp) +{ + struct fanotify_fid_event *ffe; + + ffe = kmem_cache_alloc(fanotify_fid_event_cachep, gfp); + if (!ffe) + return NULL; + + ffe->fae.type = FANOTIFY_EVENT_TYPE_FID; + ffe->fsid = *fsid; + fanotify_encode_fh(&ffe->object_fh, id, fanotify_encode_fh_len(id), + gfp); + + return &ffe->fae; +} + +static struct fanotify_event *fanotify_alloc_name_event(struct inode *id, + __kernel_fsid_t *fsid, + const struct qstr *file_name, + struct inode *child, + gfp_t gfp) +{ + struct fanotify_name_event *fne; + struct fanotify_info *info; + struct fanotify_fh *dfh, *ffh; + unsigned int dir_fh_len = fanotify_encode_fh_len(id); + unsigned int child_fh_len = fanotify_encode_fh_len(child); + unsigned int size; + + size = sizeof(*fne) + FANOTIFY_FH_HDR_LEN + dir_fh_len; + if (child_fh_len) + size += FANOTIFY_FH_HDR_LEN + child_fh_len; + if (file_name) + size += file_name->len + 1; + fne = kmalloc(size, gfp); + if (!fne) + return NULL; + + fne->fae.type = FANOTIFY_EVENT_TYPE_FID_NAME; + fne->fsid = *fsid; + info = &fne->info; + fanotify_info_init(info); + dfh = fanotify_info_dir_fh(info); + info->dir_fh_totlen = fanotify_encode_fh(dfh, id, dir_fh_len, 0); + if (child_fh_len) { + ffh = fanotify_info_file_fh(info); + info->file_fh_totlen = fanotify_encode_fh(ffh, child, child_fh_len, 0); + } + if (file_name) + fanotify_info_copy_name(info, file_name); + + pr_debug("%s: ino=%lu size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n", + __func__, id->i_ino, size, dir_fh_len, child_fh_len, + info->name_len, info->name_len, fanotify_info_name(info)); + + return &fne->fae; +} + +static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, + u32 mask, const void *data, + int data_type, struct inode *dir, + const struct qstr *file_name, + __kernel_fsid_t *fsid) +{ + struct fanotify_event *event = NULL; + gfp_t gfp = GFP_KERNEL_ACCOUNT; + struct inode *id = fanotify_fid_inode(mask, data, data_type, dir); + struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir); + const struct path *path = fsnotify_data_path(data, data_type); + unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + struct mem_cgroup *old_memcg; + struct inode *child = NULL; + bool name_event = false; + + if ((fid_mode & FAN_REPORT_DIR_FID) && dirid) { + /* + * With both flags FAN_REPORT_DIR_FID and FAN_REPORT_FID, we + * report the child fid for events reported on a non-dir child + * in addition to reporting the parent fid and maybe child name. + */ + if ((fid_mode & FAN_REPORT_FID) && + id != dirid && !(mask & FAN_ONDIR)) + child = id; + + id = dirid; + + /* + * We record file name only in a group with FAN_REPORT_NAME + * and when we have a directory inode to report. + * + * For directory entry modification event, we record the fid of + * the directory and the name of the modified entry. + * + * For event on non-directory that is reported to parent, we + * record the fid of the parent and the name of the child. + * + * Even if not reporting name, we need a variable length + * fanotify_name_event if reporting both parent and child fids. + */ + if (!(fid_mode & FAN_REPORT_NAME)) { + name_event = !!child; + file_name = NULL; + } else if ((mask & ALL_FSNOTIFY_DIRENT_EVENTS) || + !(mask & FAN_ONDIR)) { + name_event = true; + } + } + + /* + * For queues with unlimited length lost events are not expected and + * can possibly have security implications. Avoid losing events when + * memory is short. For the limited size queues, avoid OOM killer in the + * target monitoring memcg as it may have security repercussion. + */ + if (group->max_events == UINT_MAX) + gfp |= __GFP_NOFAIL; + else + gfp |= __GFP_RETRY_MAYFAIL; + + /* Whoever is interested in the event, pays for the allocation. */ + old_memcg = set_active_memcg(group->memcg); + + if (fanotify_is_perm_event(mask)) { + event = fanotify_alloc_perm_event(path, gfp); + } else if (name_event && (file_name || child)) { + event = fanotify_alloc_name_event(id, fsid, file_name, child, + gfp); + } else if (fid_mode) { + event = fanotify_alloc_fid_event(id, fsid, gfp); + } else { + event = fanotify_alloc_path_event(path, gfp); + } + + if (!event) + goto out; + + /* + * Use the victim inode instead of the watching inode as the id for + * event queue, so event reported on parent is merged with event + * reported on child when both directory and child watches exist. + */ + fanotify_init_event(event, (unsigned long)id, mask); + if (FAN_GROUP_FLAG(group, FAN_REPORT_TID)) + event->pid = get_pid(task_pid(current)); + else + event->pid = get_pid(task_tgid(current)); + +out: + set_active_memcg(old_memcg); + return event; +} + +/* + * Get cached fsid of the filesystem containing the object from any connector. + * All connectors are supposed to have the same fsid, but we do not verify that + * here. + */ +static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info) +{ + int type; + __kernel_fsid_t fsid = {}; + + fsnotify_foreach_obj_type(type) { + struct fsnotify_mark_connector *conn; + + if (!fsnotify_iter_should_report_type(iter_info, type)) + continue; + + conn = READ_ONCE(iter_info->marks[type]->connector); + /* Mark is just getting destroyed or created? */ + if (!conn) + continue; + if (!(conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID)) + continue; + /* Pairs with smp_wmb() in fsnotify_add_mark_list() */ + smp_rmb(); + fsid = conn->fsid; + if (WARN_ON_ONCE(!fsid.val[0] && !fsid.val[1])) + continue; + return fsid; + } + + return fsid; +} + +static int fanotify_handle_event(struct fsnotify_group *group, u32 mask, + const void *data, int data_type, + struct inode *dir, + const struct qstr *file_name, u32 cookie, + struct fsnotify_iter_info *iter_info) +{ + int ret = 0; + struct fanotify_event *event; + struct fsnotify_event *fsn_event; + __kernel_fsid_t fsid = {}; + + BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); + BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); + BUILD_BUG_ON(FAN_ATTRIB != FS_ATTRIB); + BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); + BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); + BUILD_BUG_ON(FAN_OPEN != FS_OPEN); + BUILD_BUG_ON(FAN_MOVED_TO != FS_MOVED_TO); + BUILD_BUG_ON(FAN_MOVED_FROM != FS_MOVED_FROM); + BUILD_BUG_ON(FAN_CREATE != FS_CREATE); + BUILD_BUG_ON(FAN_DELETE != FS_DELETE); + BUILD_BUG_ON(FAN_DELETE_SELF != FS_DELETE_SELF); + BUILD_BUG_ON(FAN_MOVE_SELF != FS_MOVE_SELF); + BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); + BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); + BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); + BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); + BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR); + BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC); + BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM); + + BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19); + + mask = fanotify_group_event_mask(group, iter_info, mask, data, + data_type, dir); + if (!mask) + return 0; + + pr_debug("%s: group=%p mask=%x\n", __func__, group, mask); + + if (fanotify_is_perm_event(mask)) { + /* + * fsnotify_prepare_user_wait() fails if we race with mark + * deletion. Just let the operation pass in that case. + */ + if (!fsnotify_prepare_user_wait(iter_info)) + return 0; + } + + if (FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS)) { + fsid = fanotify_get_fsid(iter_info); + /* Racing with mark destruction or creation? */ + if (!fsid.val[0] && !fsid.val[1]) + return 0; + } + + event = fanotify_alloc_event(group, mask, data, data_type, dir, + file_name, &fsid); + ret = -ENOMEM; + if (unlikely(!event)) { + /* + * We don't queue overflow events for permission events as + * there the access is denied and so no event is in fact lost. + */ + if (!fanotify_is_perm_event(mask)) + fsnotify_queue_overflow(group); + goto finish; + } + + fsn_event = &event->fse; + ret = fsnotify_add_event(group, fsn_event, fanotify_merge); + if (ret) { + /* Permission events shouldn't be merged */ + BUG_ON(ret == 1 && mask & FANOTIFY_PERM_EVENTS); + /* Our event wasn't used in the end. Free it. */ + fsnotify_destroy_event(group, fsn_event); + + ret = 0; + } else if (fanotify_is_perm_event(mask)) { + ret = fanotify_get_response(group, FANOTIFY_PERM(event), + iter_info); + } +finish: + if (fanotify_is_perm_event(mask)) + fsnotify_finish_user_wait(iter_info); + + return ret; +} + +static void fanotify_free_group_priv(struct fsnotify_group *group) +{ + struct user_struct *user; + + user = group->fanotify_data.user; + atomic_dec(&user->fanotify_listeners); + free_uid(user); +} + +static void fanotify_free_path_event(struct fanotify_event *event) +{ + path_put(fanotify_event_path(event)); + kmem_cache_free(fanotify_path_event_cachep, FANOTIFY_PE(event)); +} + +static void fanotify_free_perm_event(struct fanotify_event *event) +{ + path_put(fanotify_event_path(event)); + kmem_cache_free(fanotify_perm_event_cachep, FANOTIFY_PERM(event)); +} + +static void fanotify_free_fid_event(struct fanotify_event *event) +{ + struct fanotify_fid_event *ffe = FANOTIFY_FE(event); + + if (fanotify_fh_has_ext_buf(&ffe->object_fh)) + kfree(fanotify_fh_ext_buf(&ffe->object_fh)); + kmem_cache_free(fanotify_fid_event_cachep, ffe); +} + +static void fanotify_free_name_event(struct fanotify_event *event) +{ + kfree(FANOTIFY_NE(event)); +} + +static void fanotify_free_event(struct fsnotify_event *fsn_event) +{ + struct fanotify_event *event; + + event = FANOTIFY_E(fsn_event); + put_pid(event->pid); + switch (event->type) { + case FANOTIFY_EVENT_TYPE_PATH: + fanotify_free_path_event(event); + break; + case FANOTIFY_EVENT_TYPE_PATH_PERM: + fanotify_free_perm_event(event); + break; + case FANOTIFY_EVENT_TYPE_FID: + fanotify_free_fid_event(event); + break; + case FANOTIFY_EVENT_TYPE_FID_NAME: + fanotify_free_name_event(event); + break; + case FANOTIFY_EVENT_TYPE_OVERFLOW: + kfree(event); + break; + default: + WARN_ON_ONCE(1); + } +} + +static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) +{ + kmem_cache_free(fanotify_mark_cache, fsn_mark); +} + +const struct fsnotify_ops fanotify_fsnotify_ops = { + .handle_event = fanotify_handle_event, + .free_group_priv = fanotify_free_group_priv, + .free_event = fanotify_free_event, + .free_mark = fanotify_free_mark, +}; diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h new file mode 100644 index 000000000..896c819a1 --- /dev/null +++ b/fs/notify/fanotify/fanotify.h @@ -0,0 +1,286 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/fsnotify_backend.h> +#include <linux/path.h> +#include <linux/slab.h> +#include <linux/exportfs.h> + +extern struct kmem_cache *fanotify_mark_cache; +extern struct kmem_cache *fanotify_fid_event_cachep; +extern struct kmem_cache *fanotify_path_event_cachep; +extern struct kmem_cache *fanotify_perm_event_cachep; + +/* Possible states of the permission event */ +enum { + FAN_EVENT_INIT, + FAN_EVENT_REPORTED, + FAN_EVENT_ANSWERED, + FAN_EVENT_CANCELED, +}; + +/* + * 3 dwords are sufficient for most local fs (64bit ino, 32bit generation). + * fh buf should be dword aligned. On 64bit arch, the ext_buf pointer is + * stored in either the first or last 2 dwords. + */ +#define FANOTIFY_INLINE_FH_LEN (3 << 2) +#define FANOTIFY_FH_HDR_LEN offsetof(struct fanotify_fh, buf) + +/* Fixed size struct for file handle */ +struct fanotify_fh { + u8 type; + u8 len; +#define FANOTIFY_FH_FLAG_EXT_BUF 1 + u8 flags; + u8 pad; + unsigned char buf[]; +} __aligned(4); + +/* Variable size struct for dir file handle + child file handle + name */ +struct fanotify_info { + /* size of dir_fh/file_fh including fanotify_fh hdr size */ + u8 dir_fh_totlen; + u8 file_fh_totlen; + u8 name_len; + u8 pad; + unsigned char buf[]; + /* + * (struct fanotify_fh) dir_fh starts at buf[0] + * (optional) file_fh starts at buf[dir_fh_totlen] + * name starts at buf[dir_fh_totlen + file_fh_totlen] + */ +} __aligned(4); + +static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh) +{ + return (fh->flags & FANOTIFY_FH_FLAG_EXT_BUF); +} + +static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh) +{ + BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN % 4); + BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) > + FANOTIFY_INLINE_FH_LEN); + return (char **)ALIGN((unsigned long)(fh->buf), __alignof__(char *)); +} + +static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh) +{ + return *fanotify_fh_ext_buf_ptr(fh); +} + +static inline void *fanotify_fh_buf(struct fanotify_fh *fh) +{ + return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh->buf; +} + +static inline int fanotify_info_dir_fh_len(struct fanotify_info *info) +{ + if (!info->dir_fh_totlen || + WARN_ON_ONCE(info->dir_fh_totlen < FANOTIFY_FH_HDR_LEN)) + return 0; + + return info->dir_fh_totlen - FANOTIFY_FH_HDR_LEN; +} + +static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *info) +{ + BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4); + + return (struct fanotify_fh *)info->buf; +} + +static inline int fanotify_info_file_fh_len(struct fanotify_info *info) +{ + if (!info->file_fh_totlen || + WARN_ON_ONCE(info->file_fh_totlen < FANOTIFY_FH_HDR_LEN)) + return 0; + + return info->file_fh_totlen - FANOTIFY_FH_HDR_LEN; +} + +static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info) +{ + return (struct fanotify_fh *)(info->buf + info->dir_fh_totlen); +} + +static inline const char *fanotify_info_name(struct fanotify_info *info) +{ + return info->buf + info->dir_fh_totlen + info->file_fh_totlen; +} + +static inline void fanotify_info_init(struct fanotify_info *info) +{ + info->dir_fh_totlen = 0; + info->file_fh_totlen = 0; + info->name_len = 0; +} + +static inline void fanotify_info_copy_name(struct fanotify_info *info, + const struct qstr *name) +{ + info->name_len = name->len; + strcpy(info->buf + info->dir_fh_totlen + info->file_fh_totlen, + name->name); +} + +/* + * Common structure for fanotify events. Concrete structs are allocated in + * fanotify_handle_event() and freed when the information is retrieved by + * userspace. The type of event determines how it was allocated, how it will + * be freed and which concrete struct it may be cast to. + */ +enum fanotify_event_type { + FANOTIFY_EVENT_TYPE_FID, /* fixed length */ + FANOTIFY_EVENT_TYPE_FID_NAME, /* variable length */ + FANOTIFY_EVENT_TYPE_PATH, + FANOTIFY_EVENT_TYPE_PATH_PERM, + FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */ +}; + +struct fanotify_event { + struct fsnotify_event fse; + u32 mask; + enum fanotify_event_type type; + struct pid *pid; +}; + +static inline void fanotify_init_event(struct fanotify_event *event, + unsigned long id, u32 mask) +{ + fsnotify_init_event(&event->fse, id); + event->mask = mask; + event->pid = NULL; +} + +struct fanotify_fid_event { + struct fanotify_event fae; + __kernel_fsid_t fsid; + struct fanotify_fh object_fh; + /* Reserve space in object_fh.buf[] - access with fanotify_fh_buf() */ + unsigned char _inline_fh_buf[FANOTIFY_INLINE_FH_LEN]; +}; + +static inline struct fanotify_fid_event * +FANOTIFY_FE(struct fanotify_event *event) +{ + return container_of(event, struct fanotify_fid_event, fae); +} + +struct fanotify_name_event { + struct fanotify_event fae; + __kernel_fsid_t fsid; + struct fanotify_info info; +}; + +static inline struct fanotify_name_event * +FANOTIFY_NE(struct fanotify_event *event) +{ + return container_of(event, struct fanotify_name_event, fae); +} + +static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event) +{ + if (event->type == FANOTIFY_EVENT_TYPE_FID) + return &FANOTIFY_FE(event)->fsid; + else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME) + return &FANOTIFY_NE(event)->fsid; + else + return NULL; +} + +static inline struct fanotify_fh *fanotify_event_object_fh( + struct fanotify_event *event) +{ + if (event->type == FANOTIFY_EVENT_TYPE_FID) + return &FANOTIFY_FE(event)->object_fh; + else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME) + return fanotify_info_file_fh(&FANOTIFY_NE(event)->info); + else + return NULL; +} + +static inline struct fanotify_info *fanotify_event_info( + struct fanotify_event *event) +{ + if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME) + return &FANOTIFY_NE(event)->info; + else + return NULL; +} + +static inline int fanotify_event_object_fh_len(struct fanotify_event *event) +{ + struct fanotify_info *info = fanotify_event_info(event); + struct fanotify_fh *fh = fanotify_event_object_fh(event); + + if (info) + return info->file_fh_totlen ? fh->len : 0; + else + return fh ? fh->len : 0; +} + +static inline int fanotify_event_dir_fh_len(struct fanotify_event *event) +{ + struct fanotify_info *info = fanotify_event_info(event); + + return info ? fanotify_info_dir_fh_len(info) : 0; +} + +struct fanotify_path_event { + struct fanotify_event fae; + struct path path; +}; + +static inline struct fanotify_path_event * +FANOTIFY_PE(struct fanotify_event *event) +{ + return container_of(event, struct fanotify_path_event, fae); +} + +/* + * Structure for permission fanotify events. It gets allocated and freed in + * fanotify_handle_event() since we wait there for user response. When the + * information is retrieved by userspace the structure is moved from + * group->notification_list to group->fanotify_data.access_list to wait for + * user response. + */ +struct fanotify_perm_event { + struct fanotify_event fae; + struct path path; + unsigned short response; /* userspace answer to the event */ + unsigned short state; /* state of the event */ + int fd; /* fd we passed to userspace for this event */ +}; + +static inline struct fanotify_perm_event * +FANOTIFY_PERM(struct fanotify_event *event) +{ + return container_of(event, struct fanotify_perm_event, fae); +} + +static inline bool fanotify_is_perm_event(u32 mask) +{ + return IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS) && + mask & FANOTIFY_PERM_EVENTS; +} + +static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse) +{ + return container_of(fse, struct fanotify_event, fse); +} + +static inline bool fanotify_event_has_path(struct fanotify_event *event) +{ + return event->type == FANOTIFY_EVENT_TYPE_PATH || + event->type == FANOTIFY_EVENT_TYPE_PATH_PERM; +} + +static inline struct path *fanotify_event_path(struct fanotify_event *event) +{ + if (event->type == FANOTIFY_EVENT_TYPE_PATH) + return &FANOTIFY_PE(event)->path; + else if (event->type == FANOTIFY_EVENT_TYPE_PATH_PERM) + return &FANOTIFY_PERM(event)->path; + else + return NULL; +} diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c new file mode 100644 index 000000000..84de9f97b --- /dev/null +++ b/fs/notify/fanotify/fanotify_user.c @@ -0,0 +1,1349 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/fanotify.h> +#include <linux/fcntl.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/anon_inodes.h> +#include <linux/fsnotify_backend.h> +#include <linux/init.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/poll.h> +#include <linux/security.h> +#include <linux/syscalls.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/uaccess.h> +#include <linux/compat.h> +#include <linux/sched/signal.h> +#include <linux/memcontrol.h> +#include <linux/statfs.h> +#include <linux/exportfs.h> + +#include <asm/ioctls.h> + +#include "../../mount.h" +#include "../fdinfo.h" +#include "fanotify.h" + +#define FANOTIFY_DEFAULT_MAX_EVENTS 16384 +#define FANOTIFY_DEFAULT_MAX_MARKS 8192 +#define FANOTIFY_DEFAULT_MAX_LISTENERS 128 + +/* + * All flags that may be specified in parameter event_f_flags of fanotify_init. + * + * Internal and external open flags are stored together in field f_flags of + * struct file. Only external open flags shall be allowed in event_f_flags. + * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be + * excluded. + */ +#define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \ + O_ACCMODE | O_APPEND | O_NONBLOCK | \ + __O_SYNC | O_DSYNC | O_CLOEXEC | \ + O_LARGEFILE | O_NOATIME ) + +extern const struct fsnotify_ops fanotify_fsnotify_ops; + +struct kmem_cache *fanotify_mark_cache __read_mostly; +struct kmem_cache *fanotify_fid_event_cachep __read_mostly; +struct kmem_cache *fanotify_path_event_cachep __read_mostly; +struct kmem_cache *fanotify_perm_event_cachep __read_mostly; + +#define FANOTIFY_EVENT_ALIGN 4 +#define FANOTIFY_INFO_HDR_LEN \ + (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) + +static int fanotify_fid_info_len(int fh_len, int name_len) +{ + int info_len = fh_len; + + if (name_len) + info_len += name_len + 1; + + return roundup(FANOTIFY_INFO_HDR_LEN + info_len, FANOTIFY_EVENT_ALIGN); +} + +static int fanotify_event_info_len(unsigned int fid_mode, + struct fanotify_event *event) +{ + struct fanotify_info *info = fanotify_event_info(event); + int dir_fh_len = fanotify_event_dir_fh_len(event); + int fh_len = fanotify_event_object_fh_len(event); + int info_len = 0; + int dot_len = 0; + + if (dir_fh_len) { + info_len += fanotify_fid_info_len(dir_fh_len, info->name_len); + } else if ((fid_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) { + /* + * With group flag FAN_REPORT_NAME, if name was not recorded in + * event on a directory, we will report the name ".". + */ + dot_len = 1; + } + + if (fh_len) + info_len += fanotify_fid_info_len(fh_len, dot_len); + + return info_len; +} + +/* + * Get an fanotify notification event if one exists and is small + * enough to fit in "count". Return an error pointer if the count + * is not large enough. When permission event is dequeued, its state is + * updated accordingly. + */ +static struct fanotify_event *get_one_event(struct fsnotify_group *group, + size_t count) +{ + size_t event_size = FAN_EVENT_METADATA_LEN; + struct fanotify_event *event = NULL; + unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + + pr_debug("%s: group=%p count=%zd\n", __func__, group, count); + + spin_lock(&group->notification_lock); + if (fsnotify_notify_queue_is_empty(group)) + goto out; + + if (fid_mode) { + event_size += fanotify_event_info_len(fid_mode, + FANOTIFY_E(fsnotify_peek_first_event(group))); + } + + if (event_size > count) { + event = ERR_PTR(-EINVAL); + goto out; + } + event = FANOTIFY_E(fsnotify_remove_first_event(group)); + if (fanotify_is_perm_event(event->mask)) + FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED; +out: + spin_unlock(&group->notification_lock); + return event; +} + +static int create_fd(struct fsnotify_group *group, struct path *path, + struct file **file) +{ + int client_fd; + struct file *new_file; + + client_fd = get_unused_fd_flags(group->fanotify_data.f_flags); + if (client_fd < 0) + return client_fd; + + /* + * we need a new file handle for the userspace program so it can read even if it was + * originally opened O_WRONLY. + */ + new_file = dentry_open(path, + group->fanotify_data.f_flags | FMODE_NONOTIFY, + current_cred()); + if (IS_ERR(new_file)) { + /* + * we still send an event even if we can't open the file. this + * can happen when say tasks are gone and we try to open their + * /proc files or we try to open a WRONLY file like in sysfs + * we just send the errno to userspace since there isn't much + * else we can do. + */ + put_unused_fd(client_fd); + client_fd = PTR_ERR(new_file); + } else { + *file = new_file; + } + + return client_fd; +} + +/* + * Finish processing of permission event by setting it to ANSWERED state and + * drop group->notification_lock. + */ +static void finish_permission_event(struct fsnotify_group *group, + struct fanotify_perm_event *event, + unsigned int response) + __releases(&group->notification_lock) +{ + bool destroy = false; + + assert_spin_locked(&group->notification_lock); + event->response = response; + if (event->state == FAN_EVENT_CANCELED) + destroy = true; + else + event->state = FAN_EVENT_ANSWERED; + spin_unlock(&group->notification_lock); + if (destroy) + fsnotify_destroy_event(group, &event->fae.fse); +} + +static int process_access_response(struct fsnotify_group *group, + struct fanotify_response *response_struct) +{ + struct fanotify_perm_event *event; + int fd = response_struct->fd; + int response = response_struct->response; + + pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group, + fd, response); + /* + * make sure the response is valid, if invalid we do nothing and either + * userspace can send a valid response or we will clean it up after the + * timeout + */ + switch (response & ~FAN_AUDIT) { + case FAN_ALLOW: + case FAN_DENY: + break; + default: + return -EINVAL; + } + + if (fd < 0) + return -EINVAL; + + if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT)) + return -EINVAL; + + spin_lock(&group->notification_lock); + list_for_each_entry(event, &group->fanotify_data.access_list, + fae.fse.list) { + if (event->fd != fd) + continue; + + list_del_init(&event->fae.fse.list); + finish_permission_event(group, event, response); + wake_up(&group->fanotify_data.access_waitq); + return 0; + } + spin_unlock(&group->notification_lock); + + return -ENOENT; +} + +static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, + int info_type, const char *name, size_t name_len, + char __user *buf, size_t count) +{ + struct fanotify_event_info_fid info = { }; + struct file_handle handle = { }; + unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf; + size_t fh_len = fh ? fh->len : 0; + size_t info_len = fanotify_fid_info_len(fh_len, name_len); + size_t len = info_len; + + pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n", + __func__, fh_len, name_len, info_len, count); + + if (!fh_len) + return 0; + + if (WARN_ON_ONCE(len < sizeof(info) || len > count)) + return -EFAULT; + + /* + * Copy event info fid header followed by variable sized file handle + * and optionally followed by variable sized filename. + */ + switch (info_type) { + case FAN_EVENT_INFO_TYPE_FID: + case FAN_EVENT_INFO_TYPE_DFID: + if (WARN_ON_ONCE(name_len)) + return -EFAULT; + break; + case FAN_EVENT_INFO_TYPE_DFID_NAME: + if (WARN_ON_ONCE(!name || !name_len)) + return -EFAULT; + break; + default: + return -EFAULT; + } + + info.hdr.info_type = info_type; + info.hdr.len = len; + info.fsid = *fsid; + if (copy_to_user(buf, &info, sizeof(info))) + return -EFAULT; + + buf += sizeof(info); + len -= sizeof(info); + if (WARN_ON_ONCE(len < sizeof(handle))) + return -EFAULT; + + handle.handle_type = fh->type; + handle.handle_bytes = fh_len; + if (copy_to_user(buf, &handle, sizeof(handle))) + return -EFAULT; + + buf += sizeof(handle); + len -= sizeof(handle); + if (WARN_ON_ONCE(len < fh_len)) + return -EFAULT; + + /* + * For an inline fh and inline file name, copy through stack to exclude + * the copy from usercopy hardening protections. + */ + fh_buf = fanotify_fh_buf(fh); + if (fh_len <= FANOTIFY_INLINE_FH_LEN) { + memcpy(bounce, fh_buf, fh_len); + fh_buf = bounce; + } + if (copy_to_user(buf, fh_buf, fh_len)) + return -EFAULT; + + buf += fh_len; + len -= fh_len; + + if (name_len) { + /* Copy the filename with terminating null */ + name_len++; + if (WARN_ON_ONCE(len < name_len)) + return -EFAULT; + + if (copy_to_user(buf, name, name_len)) + return -EFAULT; + + buf += name_len; + len -= name_len; + } + + /* Pad with 0's */ + WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN); + if (len > 0 && clear_user(buf, len)) + return -EFAULT; + + return info_len; +} + +static ssize_t copy_event_to_user(struct fsnotify_group *group, + struct fanotify_event *event, + char __user *buf, size_t count) +{ + struct fanotify_event_metadata metadata; + struct path *path = fanotify_event_path(event); + struct fanotify_info *info = fanotify_event_info(event); + unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + struct file *f = NULL; + int ret, fd = FAN_NOFD; + int info_type = 0; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + metadata.event_len = FAN_EVENT_METADATA_LEN + + fanotify_event_info_len(fid_mode, event); + metadata.metadata_len = FAN_EVENT_METADATA_LEN; + metadata.vers = FANOTIFY_METADATA_VERSION; + metadata.reserved = 0; + metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS; + metadata.pid = pid_vnr(event->pid); + + if (path && path->mnt && path->dentry) { + fd = create_fd(group, path, &f); + if (fd < 0) + return fd; + } + metadata.fd = fd; + + ret = -EFAULT; + /* + * Sanity check copy size in case get_one_event() and + * event_len sizes ever get out of sync. + */ + if (WARN_ON_ONCE(metadata.event_len > count)) + goto out_close_fd; + + if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN)) + goto out_close_fd; + + buf += FAN_EVENT_METADATA_LEN; + count -= FAN_EVENT_METADATA_LEN; + + if (fanotify_is_perm_event(event->mask)) + FANOTIFY_PERM(event)->fd = fd; + + /* Event info records order is: dir fid + name, child fid */ + if (fanotify_event_dir_fh_len(event)) { + info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : + FAN_EVENT_INFO_TYPE_DFID; + ret = copy_info_to_user(fanotify_event_fsid(event), + fanotify_info_dir_fh(info), + info_type, fanotify_info_name(info), + info->name_len, buf, count); + if (ret < 0) + goto out_close_fd; + + buf += ret; + count -= ret; + } + + if (fanotify_event_object_fh_len(event)) { + const char *dot = NULL; + int dot_len = 0; + + if (fid_mode == FAN_REPORT_FID || info_type) { + /* + * With only group flag FAN_REPORT_FID only type FID is + * reported. Second info record type is always FID. + */ + info_type = FAN_EVENT_INFO_TYPE_FID; + } else if ((fid_mode & FAN_REPORT_NAME) && + (event->mask & FAN_ONDIR)) { + /* + * With group flag FAN_REPORT_NAME, if name was not + * recorded in an event on a directory, report the + * name "." with info type DFID_NAME. + */ + info_type = FAN_EVENT_INFO_TYPE_DFID_NAME; + dot = "."; + dot_len = 1; + } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) || + (event->mask & FAN_ONDIR)) { + /* + * With group flag FAN_REPORT_DIR_FID, a single info + * record has type DFID for directory entry modification + * event and for event on a directory. + */ + info_type = FAN_EVENT_INFO_TYPE_DFID; + } else { + /* + * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID, + * a single info record has type FID for event on a + * non-directory, when there is no directory to report. + * For example, on FAN_DELETE_SELF event. + */ + info_type = FAN_EVENT_INFO_TYPE_FID; + } + + ret = copy_info_to_user(fanotify_event_fsid(event), + fanotify_event_object_fh(event), + info_type, dot, dot_len, buf, count); + if (ret < 0) + goto out_close_fd; + + buf += ret; + count -= ret; + } + + if (f) + fd_install(fd, f); + + return metadata.event_len; + +out_close_fd: + if (fd != FAN_NOFD) { + put_unused_fd(fd); + fput(f); + } + return ret; +} + +/* intofiy userspace file descriptor functions */ +static __poll_t fanotify_poll(struct file *file, poll_table *wait) +{ + struct fsnotify_group *group = file->private_data; + __poll_t ret = 0; + + poll_wait(file, &group->notification_waitq, wait); + spin_lock(&group->notification_lock); + if (!fsnotify_notify_queue_is_empty(group)) + ret = EPOLLIN | EPOLLRDNORM; + spin_unlock(&group->notification_lock); + + return ret; +} + +static ssize_t fanotify_read(struct file *file, char __user *buf, + size_t count, loff_t *pos) +{ + struct fsnotify_group *group; + struct fanotify_event *event; + char __user *start; + int ret; + DEFINE_WAIT_FUNC(wait, woken_wake_function); + + start = buf; + group = file->private_data; + + pr_debug("%s: group=%p\n", __func__, group); + + add_wait_queue(&group->notification_waitq, &wait); + while (1) { + /* + * User can supply arbitrarily large buffer. Avoid softlockups + * in case there are lots of available events. + */ + cond_resched(); + event = get_one_event(group, count); + if (IS_ERR(event)) { + ret = PTR_ERR(event); + break; + } + + if (!event) { + ret = -EAGAIN; + if (file->f_flags & O_NONBLOCK) + break; + + ret = -ERESTARTSYS; + if (signal_pending(current)) + break; + + if (start != buf) + break; + + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + continue; + } + + ret = copy_event_to_user(group, event, buf, count); + if (unlikely(ret == -EOPENSTALE)) { + /* + * We cannot report events with stale fd so drop it. + * Setting ret to 0 will continue the event loop and + * do the right thing if there are no more events to + * read (i.e. return bytes read, -EAGAIN or wait). + */ + ret = 0; + } + + /* + * Permission events get queued to wait for response. Other + * events can be destroyed now. + */ + if (!fanotify_is_perm_event(event->mask)) { + fsnotify_destroy_event(group, &event->fse); + } else { + if (ret <= 0) { + spin_lock(&group->notification_lock); + finish_permission_event(group, + FANOTIFY_PERM(event), FAN_DENY); + wake_up(&group->fanotify_data.access_waitq); + } else { + spin_lock(&group->notification_lock); + list_add_tail(&event->fse.list, + &group->fanotify_data.access_list); + spin_unlock(&group->notification_lock); + } + } + if (ret < 0) + break; + buf += ret; + count -= ret; + } + remove_wait_queue(&group->notification_waitq, &wait); + + if (start != buf && ret != -EFAULT) + ret = buf - start; + return ret; +} + +static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) +{ + struct fanotify_response response = { .fd = -1, .response = -1 }; + struct fsnotify_group *group; + int ret; + + if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) + return -EINVAL; + + group = file->private_data; + + if (count < sizeof(response)) + return -EINVAL; + + count = sizeof(response); + + pr_debug("%s: group=%p count=%zu\n", __func__, group, count); + + if (copy_from_user(&response, buf, count)) + return -EFAULT; + + ret = process_access_response(group, &response); + if (ret < 0) + count = ret; + + return count; +} + +static int fanotify_release(struct inode *ignored, struct file *file) +{ + struct fsnotify_group *group = file->private_data; + + /* + * Stop new events from arriving in the notification queue. since + * userspace cannot use fanotify fd anymore, no event can enter or + * leave access_list by now either. + */ + fsnotify_group_stop_queueing(group); + + /* + * Process all permission events on access_list and notification queue + * and simulate reply from userspace. + */ + spin_lock(&group->notification_lock); + while (!list_empty(&group->fanotify_data.access_list)) { + struct fanotify_perm_event *event; + + event = list_first_entry(&group->fanotify_data.access_list, + struct fanotify_perm_event, fae.fse.list); + list_del_init(&event->fae.fse.list); + finish_permission_event(group, event, FAN_ALLOW); + spin_lock(&group->notification_lock); + } + + /* + * Destroy all non-permission events. For permission events just + * dequeue them and set the response. They will be freed once the + * response is consumed and fanotify_get_response() returns. + */ + while (!fsnotify_notify_queue_is_empty(group)) { + struct fanotify_event *event; + + event = FANOTIFY_E(fsnotify_remove_first_event(group)); + if (!(event->mask & FANOTIFY_PERM_EVENTS)) { + spin_unlock(&group->notification_lock); + fsnotify_destroy_event(group, &event->fse); + } else { + finish_permission_event(group, FANOTIFY_PERM(event), + FAN_ALLOW); + } + spin_lock(&group->notification_lock); + } + spin_unlock(&group->notification_lock); + + /* Response for all permission events it set, wakeup waiters */ + wake_up(&group->fanotify_data.access_waitq); + + /* matches the fanotify_init->fsnotify_alloc_group */ + fsnotify_destroy_group(group); + + return 0; +} + +static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct fsnotify_group *group; + struct fsnotify_event *fsn_event; + void __user *p; + int ret = -ENOTTY; + size_t send_len = 0; + + group = file->private_data; + + p = (void __user *) arg; + + switch (cmd) { + case FIONREAD: + spin_lock(&group->notification_lock); + list_for_each_entry(fsn_event, &group->notification_list, list) + send_len += FAN_EVENT_METADATA_LEN; + spin_unlock(&group->notification_lock); + ret = put_user(send_len, (int __user *) p); + break; + } + + return ret; +} + +static const struct file_operations fanotify_fops = { + .show_fdinfo = fanotify_show_fdinfo, + .poll = fanotify_poll, + .read = fanotify_read, + .write = fanotify_write, + .fasync = NULL, + .release = fanotify_release, + .unlocked_ioctl = fanotify_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .llseek = noop_llseek, +}; + +static int fanotify_find_path(int dfd, const char __user *filename, + struct path *path, unsigned int flags, __u64 mask, + unsigned int obj_type) +{ + int ret; + + pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, + dfd, filename, flags); + + if (filename == NULL) { + struct fd f = fdget(dfd); + + ret = -EBADF; + if (!f.file) + goto out; + + ret = -ENOTDIR; + if ((flags & FAN_MARK_ONLYDIR) && + !(S_ISDIR(file_inode(f.file)->i_mode))) { + fdput(f); + goto out; + } + + *path = f.file->f_path; + path_get(path); + fdput(f); + } else { + unsigned int lookup_flags = 0; + + if (!(flags & FAN_MARK_DONT_FOLLOW)) + lookup_flags |= LOOKUP_FOLLOW; + if (flags & FAN_MARK_ONLYDIR) + lookup_flags |= LOOKUP_DIRECTORY; + + ret = user_path_at(dfd, filename, lookup_flags, path); + if (ret) + goto out; + } + + /* you can only watch an inode if you have read permissions on it */ + ret = inode_permission(path->dentry->d_inode, MAY_READ); + if (ret) { + path_put(path); + goto out; + } + + ret = security_path_notify(path, mask, obj_type); + if (ret) + path_put(path); + +out: + return ret; +} + +static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, + __u32 mask, unsigned int flags, + __u32 umask, int *destroy) +{ + __u32 oldmask = 0; + + /* umask bits cannot be removed by user */ + mask &= ~umask; + spin_lock(&fsn_mark->lock); + if (!(flags & FAN_MARK_IGNORED_MASK)) { + oldmask = fsn_mark->mask; + fsn_mark->mask &= ~mask; + } else { + fsn_mark->ignored_mask &= ~mask; + } + /* + * We need to keep the mark around even if remaining mask cannot + * result in any events (e.g. mask == FAN_ONDIR) to support incremenal + * changes to the mask. + * Destroy mark when only umask bits remain. + */ + *destroy = !((fsn_mark->mask | fsn_mark->ignored_mask) & ~umask); + spin_unlock(&fsn_mark->lock); + + return mask & oldmask; +} + +static int fanotify_remove_mark(struct fsnotify_group *group, + fsnotify_connp_t *connp, __u32 mask, + unsigned int flags, __u32 umask) +{ + struct fsnotify_mark *fsn_mark = NULL; + __u32 removed; + int destroy_mark; + + mutex_lock(&group->mark_mutex); + fsn_mark = fsnotify_find_mark(connp, group); + if (!fsn_mark) { + mutex_unlock(&group->mark_mutex); + return -ENOENT; + } + + removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, + umask, &destroy_mark); + if (removed & fsnotify_conn_mask(fsn_mark->connector)) + fsnotify_recalc_mask(fsn_mark->connector); + if (destroy_mark) + fsnotify_detach_mark(fsn_mark); + mutex_unlock(&group->mark_mutex); + if (destroy_mark) + fsnotify_free_mark(fsn_mark); + + /* matches the fsnotify_find_mark() */ + fsnotify_put_mark(fsn_mark); + return 0; +} + +static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, + struct vfsmount *mnt, __u32 mask, + unsigned int flags, __u32 umask) +{ + return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, + mask, flags, umask); +} + +static int fanotify_remove_sb_mark(struct fsnotify_group *group, + struct super_block *sb, __u32 mask, + unsigned int flags, __u32 umask) +{ + return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, + flags, umask); +} + +static int fanotify_remove_inode_mark(struct fsnotify_group *group, + struct inode *inode, __u32 mask, + unsigned int flags, __u32 umask) +{ + return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask, + flags, umask); +} + +static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, + __u32 mask, + unsigned int flags) +{ + __u32 oldmask = -1; + + spin_lock(&fsn_mark->lock); + if (!(flags & FAN_MARK_IGNORED_MASK)) { + oldmask = fsn_mark->mask; + fsn_mark->mask |= mask; + } else { + fsn_mark->ignored_mask |= mask; + if (flags & FAN_MARK_IGNORED_SURV_MODIFY) + fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; + } + spin_unlock(&fsn_mark->lock); + + return mask & ~oldmask; +} + +static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, + fsnotify_connp_t *connp, + unsigned int type, + __kernel_fsid_t *fsid) +{ + struct fsnotify_mark *mark; + int ret; + + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return ERR_PTR(-ENOSPC); + + mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); + if (!mark) + return ERR_PTR(-ENOMEM); + + fsnotify_init_mark(mark, group); + ret = fsnotify_add_mark_locked(mark, connp, type, 0, fsid); + if (ret) { + fsnotify_put_mark(mark); + return ERR_PTR(ret); + } + + return mark; +} + + +static int fanotify_add_mark(struct fsnotify_group *group, + fsnotify_connp_t *connp, unsigned int type, + __u32 mask, unsigned int flags, + __kernel_fsid_t *fsid) +{ + struct fsnotify_mark *fsn_mark; + __u32 added; + + mutex_lock(&group->mark_mutex); + fsn_mark = fsnotify_find_mark(connp, group); + if (!fsn_mark) { + fsn_mark = fanotify_add_new_mark(group, connp, type, fsid); + if (IS_ERR(fsn_mark)) { + mutex_unlock(&group->mark_mutex); + return PTR_ERR(fsn_mark); + } + } + added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); + if (added & ~fsnotify_conn_mask(fsn_mark->connector)) + fsnotify_recalc_mask(fsn_mark->connector); + mutex_unlock(&group->mark_mutex); + + fsnotify_put_mark(fsn_mark); + return 0; +} + +static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, + struct vfsmount *mnt, __u32 mask, + unsigned int flags, __kernel_fsid_t *fsid) +{ + return fanotify_add_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, + FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags, fsid); +} + +static int fanotify_add_sb_mark(struct fsnotify_group *group, + struct super_block *sb, __u32 mask, + unsigned int flags, __kernel_fsid_t *fsid) +{ + return fanotify_add_mark(group, &sb->s_fsnotify_marks, + FSNOTIFY_OBJ_TYPE_SB, mask, flags, fsid); +} + +static int fanotify_add_inode_mark(struct fsnotify_group *group, + struct inode *inode, __u32 mask, + unsigned int flags, __kernel_fsid_t *fsid) +{ + pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); + + /* + * If some other task has this inode open for write we should not add + * an ignored mark, unless that ignored mark is supposed to survive + * modification changes anyway. + */ + if ((flags & FAN_MARK_IGNORED_MASK) && + !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && + inode_is_open_for_write(inode)) + return 0; + + return fanotify_add_mark(group, &inode->i_fsnotify_marks, + FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid); +} + +static struct fsnotify_event *fanotify_alloc_overflow_event(void) +{ + struct fanotify_event *oevent; + + oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT); + if (!oevent) + return NULL; + + fanotify_init_event(oevent, 0, FS_Q_OVERFLOW); + oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW; + + return &oevent->fse; +} + +/* fanotify syscalls */ +SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) +{ + struct fsnotify_group *group; + int f_flags, fd; + struct user_struct *user; + unsigned int fid_mode = flags & FANOTIFY_FID_BITS; + unsigned int class = flags & FANOTIFY_CLASS_BITS; + + pr_debug("%s: flags=%x event_f_flags=%x\n", + __func__, flags, event_f_flags); + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + +#ifdef CONFIG_AUDITSYSCALL + if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT)) +#else + if (flags & ~FANOTIFY_INIT_FLAGS) +#endif + return -EINVAL; + + if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) + return -EINVAL; + + switch (event_f_flags & O_ACCMODE) { + case O_RDONLY: + case O_RDWR: + case O_WRONLY: + break; + default: + return -EINVAL; + } + + if (fid_mode && class != FAN_CLASS_NOTIF) + return -EINVAL; + + /* + * Child name is reported with parent fid so requires dir fid. + * We can report both child fid and dir fid with or without name. + */ + if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID)) + return -EINVAL; + + user = get_current_user(); + if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { + free_uid(user); + return -EMFILE; + } + + f_flags = O_RDWR | FMODE_NONOTIFY; + if (flags & FAN_CLOEXEC) + f_flags |= O_CLOEXEC; + if (flags & FAN_NONBLOCK) + f_flags |= O_NONBLOCK; + + /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ + group = fsnotify_alloc_group(&fanotify_fsnotify_ops); + if (IS_ERR(group)) { + free_uid(user); + return PTR_ERR(group); + } + + group->fanotify_data.user = user; + group->fanotify_data.flags = flags; + atomic_inc(&user->fanotify_listeners); + group->memcg = get_mem_cgroup_from_mm(current->mm); + + group->overflow_event = fanotify_alloc_overflow_event(); + if (unlikely(!group->overflow_event)) { + fd = -ENOMEM; + goto out_destroy_group; + } + + if (force_o_largefile()) + event_f_flags |= O_LARGEFILE; + group->fanotify_data.f_flags = event_f_flags; + init_waitqueue_head(&group->fanotify_data.access_waitq); + INIT_LIST_HEAD(&group->fanotify_data.access_list); + switch (class) { + case FAN_CLASS_NOTIF: + group->priority = FS_PRIO_0; + break; + case FAN_CLASS_CONTENT: + group->priority = FS_PRIO_1; + break; + case FAN_CLASS_PRE_CONTENT: + group->priority = FS_PRIO_2; + break; + default: + fd = -EINVAL; + goto out_destroy_group; + } + + if (flags & FAN_UNLIMITED_QUEUE) { + fd = -EPERM; + if (!capable(CAP_SYS_ADMIN)) + goto out_destroy_group; + group->max_events = UINT_MAX; + } else { + group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; + } + + if (flags & FAN_UNLIMITED_MARKS) { + fd = -EPERM; + if (!capable(CAP_SYS_ADMIN)) + goto out_destroy_group; + group->fanotify_data.max_marks = UINT_MAX; + } else { + group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; + } + + if (flags & FAN_ENABLE_AUDIT) { + fd = -EPERM; + if (!capable(CAP_AUDIT_WRITE)) + goto out_destroy_group; + } + + fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); + if (fd < 0) + goto out_destroy_group; + + return fd; + +out_destroy_group: + fsnotify_destroy_group(group); + return fd; +} + +/* Check if filesystem can encode a unique fid */ +static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid) +{ + __kernel_fsid_t root_fsid; + int err; + + /* + * Make sure path is not in filesystem with zero fsid (e.g. tmpfs). + */ + err = vfs_get_fsid(path->dentry, fsid); + if (err) + return err; + + if (!fsid->val[0] && !fsid->val[1]) + return -ENODEV; + + /* + * Make sure path is not inside a filesystem subvolume (e.g. btrfs) + * which uses a different fsid than sb root. + */ + err = vfs_get_fsid(path->dentry->d_sb->s_root, &root_fsid); + if (err) + return err; + + if (root_fsid.val[0] != fsid->val[0] || + root_fsid.val[1] != fsid->val[1]) + return -EXDEV; + + /* + * We need to make sure that the file system supports at least + * encoding a file handle so user can use name_to_handle_at() to + * compare fid returned with event to the file handle of watched + * objects. However, name_to_handle_at() requires that the + * filesystem also supports decoding file handles. + */ + if (!path->dentry->d_sb->s_export_op || + !path->dentry->d_sb->s_export_op->fh_to_dentry) + return -EOPNOTSUPP; + + return 0; +} + +static int fanotify_events_supported(struct path *path, __u64 mask, + unsigned int flags) +{ + unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; + + /* + * Some filesystems such as 'proc' acquire unusual locks when opening + * files. For them fanotify permission events have high chances of + * deadlocking the system - open done when reporting fanotify event + * blocks on this "unusual" lock while another process holding the lock + * waits for fanotify permission event to be answered. Just disallow + * permission events for such filesystems. + */ + if (mask & FANOTIFY_PERM_EVENTS && + path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM) + return -EINVAL; + + /* + * mount and sb marks are not allowed on kernel internal pseudo fs, + * like pipe_mnt, because that would subscribe to events on all the + * anonynous pipes in the system. + * + * SB_NOUSER covers all of the internal pseudo fs whose objects are not + * exposed to user's mount namespace, but there are other SB_KERNMOUNT + * fs, like nsfs, debugfs, for which the value of allowing sb and mount + * mark is questionable. For now we leave them alone. + */ + if (mark_type != FAN_MARK_INODE && + path->mnt->mnt_sb->s_flags & SB_NOUSER) + return -EINVAL; + + return 0; +} + +static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, + int dfd, const char __user *pathname) +{ + struct inode *inode = NULL; + struct vfsmount *mnt = NULL; + struct fsnotify_group *group; + struct fd f; + struct path path; + __kernel_fsid_t __fsid, *fsid = NULL; + u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS; + unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; + bool ignored = flags & FAN_MARK_IGNORED_MASK; + unsigned int obj_type, fid_mode; + u32 umask = 0; + int ret; + + pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", + __func__, fanotify_fd, flags, dfd, pathname, mask); + + /* we only use the lower 32 bits as of right now. */ + if (mask & ((__u64)0xffffffff << 32)) + return -EINVAL; + + if (flags & ~FANOTIFY_MARK_FLAGS) + return -EINVAL; + + switch (mark_type) { + case FAN_MARK_INODE: + obj_type = FSNOTIFY_OBJ_TYPE_INODE; + break; + case FAN_MARK_MOUNT: + obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT; + break; + case FAN_MARK_FILESYSTEM: + obj_type = FSNOTIFY_OBJ_TYPE_SB; + break; + default: + return -EINVAL; + } + + switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { + case FAN_MARK_ADD: + case FAN_MARK_REMOVE: + if (!mask) + return -EINVAL; + break; + case FAN_MARK_FLUSH: + if (flags & ~(FANOTIFY_MARK_TYPE_BITS | FAN_MARK_FLUSH)) + return -EINVAL; + break; + default: + return -EINVAL; + } + + if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) + valid_mask |= FANOTIFY_PERM_EVENTS; + + if (mask & ~valid_mask) + return -EINVAL; + + /* Event flags (ONDIR, ON_CHILD) are meaningless in ignored mask */ + if (ignored) + mask &= ~FANOTIFY_EVENT_FLAGS; + + f = fdget(fanotify_fd); + if (unlikely(!f.file)) + return -EBADF; + + /* verify that this is indeed an fanotify instance */ + ret = -EINVAL; + if (unlikely(f.file->f_op != &fanotify_fops)) + goto fput_and_out; + group = f.file->private_data; + + /* + * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not + * allowed to set permissions events. + */ + ret = -EINVAL; + if (mask & FANOTIFY_PERM_EVENTS && + group->priority == FS_PRIO_0) + goto fput_and_out; + + /* + * Events with data type inode do not carry enough information to report + * event->fd, so we do not allow setting a mask for inode events unless + * group supports reporting fid. + * inode events are not supported on a mount mark, because they do not + * carry enough information (i.e. path) to be filtered by mount point. + */ + fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + if (mask & FANOTIFY_INODE_EVENTS && + (!fid_mode || mark_type == FAN_MARK_MOUNT)) + goto fput_and_out; + + if (flags & FAN_MARK_FLUSH) { + ret = 0; + if (mark_type == FAN_MARK_MOUNT) + fsnotify_clear_vfsmount_marks_by_group(group); + else if (mark_type == FAN_MARK_FILESYSTEM) + fsnotify_clear_sb_marks_by_group(group); + else + fsnotify_clear_inode_marks_by_group(group); + goto fput_and_out; + } + + ret = fanotify_find_path(dfd, pathname, &path, flags, + (mask & ALL_FSNOTIFY_EVENTS), obj_type); + if (ret) + goto fput_and_out; + + if (flags & FAN_MARK_ADD) { + ret = fanotify_events_supported(&path, mask, flags); + if (ret) + goto path_put_and_out; + } + + if (fid_mode) { + ret = fanotify_test_fid(&path, &__fsid); + if (ret) + goto path_put_and_out; + + fsid = &__fsid; + } + + /* inode held in place by reference to path; group by fget on fd */ + if (mark_type == FAN_MARK_INODE) + inode = path.dentry->d_inode; + else + mnt = path.mnt; + + /* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */ + if (mnt || !S_ISDIR(inode->i_mode)) { + mask &= ~FAN_EVENT_ON_CHILD; + umask = FAN_EVENT_ON_CHILD; + /* + * If group needs to report parent fid, register for getting + * events with parent/name info for non-directory. + */ + if ((fid_mode & FAN_REPORT_DIR_FID) && + (flags & FAN_MARK_ADD) && !ignored) + mask |= FAN_EVENT_ON_CHILD; + } + + /* create/update an inode mark */ + switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) { + case FAN_MARK_ADD: + if (mark_type == FAN_MARK_MOUNT) + ret = fanotify_add_vfsmount_mark(group, mnt, mask, + flags, fsid); + else if (mark_type == FAN_MARK_FILESYSTEM) + ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask, + flags, fsid); + else + ret = fanotify_add_inode_mark(group, inode, mask, + flags, fsid); + break; + case FAN_MARK_REMOVE: + if (mark_type == FAN_MARK_MOUNT) + ret = fanotify_remove_vfsmount_mark(group, mnt, mask, + flags, umask); + else if (mark_type == FAN_MARK_FILESYSTEM) + ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask, + flags, umask); + else + ret = fanotify_remove_inode_mark(group, inode, mask, + flags, umask); + break; + default: + ret = -EINVAL; + } + +path_put_and_out: + path_put(&path); +fput_and_out: + fdput(f); + return ret; +} + +#ifndef CONFIG_ARCH_SPLIT_ARG64 +SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, + __u64, mask, int, dfd, + const char __user *, pathname) +{ + return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname); +} +#endif + +#if defined(CONFIG_ARCH_SPLIT_ARG64) || defined(CONFIG_COMPAT) +SYSCALL32_DEFINE6(fanotify_mark, + int, fanotify_fd, unsigned int, flags, + SC_ARG64(mask), int, dfd, + const char __user *, pathname) +{ + return do_fanotify_mark(fanotify_fd, flags, SC_VAL64(__u64, mask), + dfd, pathname); +} +#endif + +/* + * fanotify_user_setup - Our initialization function. Note that we cannot return + * error because we have compiled-in VFS hooks. So an (unlikely) failure here + * must result in panic(). + */ +static int __init fanotify_user_setup(void) +{ + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 10); + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9); + + fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, + SLAB_PANIC|SLAB_ACCOUNT); + fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event, + SLAB_PANIC); + fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_event, + SLAB_PANIC); + if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) { + fanotify_perm_event_cachep = + KMEM_CACHE(fanotify_perm_event, SLAB_PANIC); + } + + return 0; +} +device_initcall(fanotify_user_setup); diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c new file mode 100644 index 000000000..765b50aea --- /dev/null +++ b/fs/notify/fdinfo.c @@ -0,0 +1,149 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/fsnotify_backend.h> +#include <linux/idr.h> +#include <linux/init.h> +#include <linux/inotify.h> +#include <linux/fanotify.h> +#include <linux/kernel.h> +#include <linux/namei.h> +#include <linux/sched.h> +#include <linux/types.h> +#include <linux/seq_file.h> +#include <linux/exportfs.h> + +#include "inotify/inotify.h" +#include "fdinfo.h" +#include "fsnotify.h" + +#if defined(CONFIG_PROC_FS) + +#if defined(CONFIG_INOTIFY_USER) || defined(CONFIG_FANOTIFY) + +static void show_fdinfo(struct seq_file *m, struct file *f, + void (*show)(struct seq_file *m, + struct fsnotify_mark *mark)) +{ + struct fsnotify_group *group = f->private_data; + struct fsnotify_mark *mark; + + mutex_lock(&group->mark_mutex); + list_for_each_entry(mark, &group->marks_list, g_list) { + show(m, mark); + if (seq_has_overflowed(m)) + break; + } + mutex_unlock(&group->mark_mutex); +} + +#if defined(CONFIG_EXPORTFS) +static void show_mark_fhandle(struct seq_file *m, struct inode *inode) +{ + struct { + struct file_handle handle; + u8 pad[MAX_HANDLE_SZ]; + } f; + int size, ret, i; + + f.handle.handle_bytes = sizeof(f.pad); + size = f.handle.handle_bytes >> 2; + + ret = exportfs_encode_inode_fh(inode, (struct fid *)f.handle.f_handle, &size, NULL); + if ((ret == FILEID_INVALID) || (ret < 0)) { + WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret); + return; + } + + f.handle.handle_type = ret; + f.handle.handle_bytes = size * sizeof(u32); + + seq_printf(m, "fhandle-bytes:%x fhandle-type:%x f_handle:", + f.handle.handle_bytes, f.handle.handle_type); + + for (i = 0; i < f.handle.handle_bytes; i++) + seq_printf(m, "%02x", (int)f.handle.f_handle[i]); +} +#else +static void show_mark_fhandle(struct seq_file *m, struct inode *inode) +{ +} +#endif + +#ifdef CONFIG_INOTIFY_USER + +static void inotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark) +{ + struct inotify_inode_mark *inode_mark; + struct inode *inode; + + if (mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE) + return; + + inode_mark = container_of(mark, struct inotify_inode_mark, fsn_mark); + inode = igrab(fsnotify_conn_inode(mark->connector)); + if (inode) { + seq_printf(m, "inotify wd:%x ino:%lx sdev:%x mask:%x ignored_mask:0 ", + inode_mark->wd, inode->i_ino, inode->i_sb->s_dev, + inotify_mark_user_mask(mark)); + show_mark_fhandle(m, inode); + seq_putc(m, '\n'); + iput(inode); + } +} + +void inotify_show_fdinfo(struct seq_file *m, struct file *f) +{ + show_fdinfo(m, f, inotify_fdinfo); +} + +#endif /* CONFIG_INOTIFY_USER */ + +#ifdef CONFIG_FANOTIFY + +static void fanotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark) +{ + unsigned int mflags = 0; + struct inode *inode; + + if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY) + mflags |= FAN_MARK_IGNORED_SURV_MODIFY; + + if (mark->connector->type == FSNOTIFY_OBJ_TYPE_INODE) { + inode = igrab(fsnotify_conn_inode(mark->connector)); + if (!inode) + return; + seq_printf(m, "fanotify ino:%lx sdev:%x mflags:%x mask:%x ignored_mask:%x ", + inode->i_ino, inode->i_sb->s_dev, + mflags, mark->mask, mark->ignored_mask); + show_mark_fhandle(m, inode); + seq_putc(m, '\n'); + iput(inode); + } else if (mark->connector->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) { + struct mount *mnt = fsnotify_conn_mount(mark->connector); + + seq_printf(m, "fanotify mnt_id:%x mflags:%x mask:%x ignored_mask:%x\n", + mnt->mnt_id, mflags, mark->mask, mark->ignored_mask); + } else if (mark->connector->type == FSNOTIFY_OBJ_TYPE_SB) { + struct super_block *sb = fsnotify_conn_sb(mark->connector); + + seq_printf(m, "fanotify sdev:%x mflags:%x mask:%x ignored_mask:%x\n", + sb->s_dev, mflags, mark->mask, mark->ignored_mask); + } +} + +void fanotify_show_fdinfo(struct seq_file *m, struct file *f) +{ + struct fsnotify_group *group = f->private_data; + + seq_printf(m, "fanotify flags:%x event-flags:%x\n", + group->fanotify_data.flags, group->fanotify_data.f_flags); + + show_fdinfo(m, f, fanotify_fdinfo); +} + +#endif /* CONFIG_FANOTIFY */ + +#endif /* CONFIG_INOTIFY_USER || CONFIG_FANOTIFY */ + +#endif /* CONFIG_PROC_FS */ diff --git a/fs/notify/fdinfo.h b/fs/notify/fdinfo.h new file mode 100644 index 000000000..5c9937e02 --- /dev/null +++ b/fs/notify/fdinfo.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __FSNOTIFY_FDINFO_H__ +#define __FSNOTIFY_FDINFO_H__ + +#include <linux/errno.h> +#include <linux/proc_fs.h> + +struct seq_file; +struct file; + +#ifdef CONFIG_PROC_FS + +#ifdef CONFIG_INOTIFY_USER +void inotify_show_fdinfo(struct seq_file *m, struct file *f); +#endif + +#ifdef CONFIG_FANOTIFY +void fanotify_show_fdinfo(struct seq_file *m, struct file *f); +#endif + +#else /* CONFIG_PROC_FS */ + +#define inotify_show_fdinfo NULL +#define fanotify_show_fdinfo NULL + +#endif /* CONFIG_PROC_FS */ + +#endif /* __FSNOTIFY_FDINFO_H__ */ diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c new file mode 100644 index 000000000..30d422b8c --- /dev/null +++ b/fs/notify/fsnotify.c @@ -0,0 +1,572 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + */ + +#include <linux/dcache.h> +#include <linux/fs.h> +#include <linux/gfp.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/mount.h> +#include <linux/srcu.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +/* + * Clear all of the marks on an inode when it is being evicted from core + */ +void __fsnotify_inode_delete(struct inode *inode) +{ + fsnotify_clear_marks_by_inode(inode); +} +EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); + +void __fsnotify_vfsmount_delete(struct vfsmount *mnt) +{ + fsnotify_clear_marks_by_mount(mnt); +} + +/** + * fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes. + * @sb: superblock being unmounted. + * + * Called during unmount with no locks held, so needs to be safe against + * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block. + */ +static void fsnotify_unmount_inodes(struct super_block *sb) +{ + struct inode *inode, *iput_inode = NULL; + + spin_lock(&sb->s_inode_list_lock); + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { + /* + * We cannot __iget() an inode in state I_FREEING, + * I_WILL_FREE, or I_NEW which is fine because by that point + * the inode cannot have any associated watches. + */ + spin_lock(&inode->i_lock); + if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { + spin_unlock(&inode->i_lock); + continue; + } + + /* + * If i_count is zero, the inode cannot have any watches and + * doing an __iget/iput with SB_ACTIVE clear would actually + * evict all inodes with zero i_count from icache which is + * unnecessarily violent and may in fact be illegal to do. + * However, we should have been called /after/ evict_inodes + * removed all zero refcount inodes, in any case. Test to + * be sure. + */ + if (!atomic_read(&inode->i_count)) { + spin_unlock(&inode->i_lock); + continue; + } + + __iget(inode); + spin_unlock(&inode->i_lock); + spin_unlock(&sb->s_inode_list_lock); + + if (iput_inode) + iput(iput_inode); + + /* for each watch, send FS_UNMOUNT and then remove it */ + fsnotify_inode(inode, FS_UNMOUNT); + + fsnotify_inode_delete(inode); + + iput_inode = inode; + + cond_resched(); + spin_lock(&sb->s_inode_list_lock); + } + spin_unlock(&sb->s_inode_list_lock); + + if (iput_inode) + iput(iput_inode); + /* Wait for outstanding inode references from connectors */ + wait_var_event(&sb->s_fsnotify_inode_refs, + !atomic_long_read(&sb->s_fsnotify_inode_refs)); +} + +void fsnotify_sb_delete(struct super_block *sb) +{ + fsnotify_unmount_inodes(sb); + fsnotify_clear_marks_by_sb(sb); +} + +/* + * Given an inode, first check if we care what happens to our children. Inotify + * and dnotify both tell their parents about events. If we care about any event + * on a child we run all of our children and set a dentry flag saying that the + * parent cares. Thus when an event happens on a child it can quickly tell if + * if there is a need to find a parent and send the event to the parent. + */ +void __fsnotify_update_child_dentry_flags(struct inode *inode) +{ + struct dentry *alias; + int watched; + + if (!S_ISDIR(inode->i_mode)) + return; + + /* determine if the children should tell inode about their events */ + watched = fsnotify_inode_watches_children(inode); + + spin_lock(&inode->i_lock); + /* run all of the dentries associated with this inode. Since this is a + * directory, there damn well better only be one item on this list */ + hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { + struct dentry *child; + + /* run all of the children of the original inode and fix their + * d_flags to indicate parental interest (their parent is the + * original inode) */ + spin_lock(&alias->d_lock); + list_for_each_entry(child, &alias->d_subdirs, d_child) { + if (!child->d_inode) + continue; + + spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); + if (watched) + child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; + else + child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; + spin_unlock(&child->d_lock); + } + spin_unlock(&alias->d_lock); + } + spin_unlock(&inode->i_lock); +} + +/* Are inode/sb/mount interested in parent and name info with this event? */ +static bool fsnotify_event_needs_parent(struct inode *inode, struct mount *mnt, + __u32 mask) +{ + __u32 marks_mask = 0; + + /* We only send parent/name to inode/sb/mount for events on non-dir */ + if (mask & FS_ISDIR) + return false; + + /* + * All events that are possible on child can also may be reported with + * parent/name info to inode/sb/mount. Otherwise, a watching parent + * could result in events reported with unexpected name info to sb/mount. + */ + BUILD_BUG_ON(FS_EVENTS_POSS_ON_CHILD & ~FS_EVENTS_POSS_TO_PARENT); + + /* Did either inode/sb/mount subscribe for events with parent/name? */ + marks_mask |= fsnotify_parent_needed_mask(inode->i_fsnotify_mask); + marks_mask |= fsnotify_parent_needed_mask(inode->i_sb->s_fsnotify_mask); + if (mnt) + marks_mask |= fsnotify_parent_needed_mask(mnt->mnt_fsnotify_mask); + + /* Did they subscribe for this event with parent/name info? */ + return mask & marks_mask; +} + +/* + * Notify this dentry's parent about a child's events with child name info + * if parent is watching or if inode/sb/mount are interested in events with + * parent and name info. + * + * Notify only the child without name info if parent is not watching and + * inode/sb/mount are not interested in events with parent and name info. + */ +int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data, + int data_type) +{ + const struct path *path = fsnotify_data_path(data, data_type); + struct mount *mnt = path ? real_mount(path->mnt) : NULL; + struct inode *inode = d_inode(dentry); + struct dentry *parent; + bool parent_watched = dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED; + bool parent_needed, parent_interested; + __u32 p_mask; + struct inode *p_inode = NULL; + struct name_snapshot name; + struct qstr *file_name = NULL; + int ret = 0; + + /* + * Do inode/sb/mount care about parent and name info on non-dir? + * Do they care about any event at all? + */ + if (!inode->i_fsnotify_marks && !inode->i_sb->s_fsnotify_marks && + (!mnt || !mnt->mnt_fsnotify_marks) && !parent_watched) + return 0; + + parent = NULL; + parent_needed = fsnotify_event_needs_parent(inode, mnt, mask); + if (!parent_watched && !parent_needed) + goto notify; + + /* Does parent inode care about events on children? */ + parent = dget_parent(dentry); + p_inode = parent->d_inode; + p_mask = fsnotify_inode_watches_children(p_inode); + if (unlikely(parent_watched && !p_mask)) + __fsnotify_update_child_dentry_flags(p_inode); + + /* + * Include parent/name in notification either if some notification + * groups require parent info or the parent is interested in this event. + */ + parent_interested = mask & p_mask & ALL_FSNOTIFY_EVENTS; + if (parent_needed || parent_interested) { + /* When notifying parent, child should be passed as data */ + WARN_ON_ONCE(inode != fsnotify_data_inode(data, data_type)); + + /* Notify both parent and child with child name info */ + take_dentry_name_snapshot(&name, dentry); + file_name = &name.name; + if (parent_interested) + mask |= FS_EVENT_ON_CHILD; + } + +notify: + ret = fsnotify(mask, data, data_type, p_inode, file_name, inode, 0); + + if (file_name) + release_dentry_name_snapshot(&name); + dput(parent); + + return ret; +} +EXPORT_SYMBOL_GPL(__fsnotify_parent); + +static int fsnotify_handle_inode_event(struct fsnotify_group *group, + struct fsnotify_mark *inode_mark, + u32 mask, const void *data, int data_type, + struct inode *dir, const struct qstr *name, + u32 cookie) +{ + const struct path *path = fsnotify_data_path(data, data_type); + struct inode *inode = fsnotify_data_inode(data, data_type); + const struct fsnotify_ops *ops = group->ops; + + if (WARN_ON_ONCE(!ops->handle_inode_event)) + return 0; + + if ((inode_mark->mask & FS_EXCL_UNLINK) && + path && d_unlinked(path->dentry)) + return 0; + + /* Check interest of this mark in case event was sent with two marks */ + if (!(mask & inode_mark->mask & ALL_FSNOTIFY_EVENTS)) + return 0; + + return ops->handle_inode_event(inode_mark, mask, inode, dir, name, cookie); +} + +static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask, + const void *data, int data_type, + struct inode *dir, const struct qstr *name, + u32 cookie, struct fsnotify_iter_info *iter_info) +{ + struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info); + struct fsnotify_mark *parent_mark = fsnotify_iter_parent_mark(iter_info); + int ret; + + if (WARN_ON_ONCE(fsnotify_iter_sb_mark(iter_info)) || + WARN_ON_ONCE(fsnotify_iter_vfsmount_mark(iter_info))) + return 0; + + if (parent_mark) { + /* + * parent_mark indicates that the parent inode is watching + * children and interested in this event, which is an event + * possible on child. But is *this mark* watching children and + * interested in this event? + */ + if (parent_mark->mask & FS_EVENT_ON_CHILD) { + ret = fsnotify_handle_inode_event(group, parent_mark, mask, + data, data_type, dir, name, 0); + if (ret) + return ret; + } + if (!inode_mark) + return 0; + } + + if (mask & FS_EVENT_ON_CHILD) { + /* + * Some events can be sent on both parent dir and child marks + * (e.g. FS_ATTRIB). If both parent dir and child are + * watching, report the event once to parent dir with name (if + * interested) and once to child without name (if interested). + * The child watcher is expecting an event without a file name + * and without the FS_EVENT_ON_CHILD flag. + */ + mask &= ~FS_EVENT_ON_CHILD; + dir = NULL; + name = NULL; + } + + return fsnotify_handle_inode_event(group, inode_mark, mask, data, data_type, + dir, name, cookie); +} + +static int send_to_group(__u32 mask, const void *data, int data_type, + struct inode *dir, const struct qstr *file_name, + u32 cookie, struct fsnotify_iter_info *iter_info) +{ + struct fsnotify_group *group = NULL; + __u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS); + __u32 marks_mask = 0; + __u32 marks_ignored_mask = 0; + struct fsnotify_mark *mark; + int type; + + if (WARN_ON(!iter_info->report_mask)) + return 0; + + /* clear ignored on inode modification */ + if (mask & FS_MODIFY) { + fsnotify_foreach_obj_type(type) { + if (!fsnotify_iter_should_report_type(iter_info, type)) + continue; + mark = iter_info->marks[type]; + if (mark && + !(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) + mark->ignored_mask = 0; + } + } + + fsnotify_foreach_obj_type(type) { + if (!fsnotify_iter_should_report_type(iter_info, type)) + continue; + mark = iter_info->marks[type]; + /* does the object mark tell us to do something? */ + if (mark) { + group = mark->group; + marks_mask |= mark->mask; + marks_ignored_mask |= mark->ignored_mask; + } + } + + pr_debug("%s: group=%p mask=%x marks_mask=%x marks_ignored_mask=%x data=%p data_type=%d dir=%p cookie=%d\n", + __func__, group, mask, marks_mask, marks_ignored_mask, + data, data_type, dir, cookie); + + if (!(test_mask & marks_mask & ~marks_ignored_mask)) + return 0; + + if (group->ops->handle_event) { + return group->ops->handle_event(group, mask, data, data_type, dir, + file_name, cookie, iter_info); + } + + return fsnotify_handle_event(group, mask, data, data_type, dir, + file_name, cookie, iter_info); +} + +static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp) +{ + struct fsnotify_mark_connector *conn; + struct hlist_node *node = NULL; + + conn = srcu_dereference(*connp, &fsnotify_mark_srcu); + if (conn) + node = srcu_dereference(conn->list.first, &fsnotify_mark_srcu); + + return hlist_entry_safe(node, struct fsnotify_mark, obj_list); +} + +static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark) +{ + struct hlist_node *node = NULL; + + if (mark) + node = srcu_dereference(mark->obj_list.next, + &fsnotify_mark_srcu); + + return hlist_entry_safe(node, struct fsnotify_mark, obj_list); +} + +/* + * iter_info is a multi head priority queue of marks. + * Pick a subset of marks from queue heads, all with the + * same group and set the report_mask for selected subset. + * Returns the report_mask of the selected subset. + */ +static unsigned int fsnotify_iter_select_report_types( + struct fsnotify_iter_info *iter_info) +{ + struct fsnotify_group *max_prio_group = NULL; + struct fsnotify_mark *mark; + int type; + + /* Choose max prio group among groups of all queue heads */ + fsnotify_foreach_obj_type(type) { + mark = iter_info->marks[type]; + if (mark && + fsnotify_compare_groups(max_prio_group, mark->group) > 0) + max_prio_group = mark->group; + } + + if (!max_prio_group) + return 0; + + /* Set the report mask for marks from same group as max prio group */ + iter_info->report_mask = 0; + fsnotify_foreach_obj_type(type) { + mark = iter_info->marks[type]; + if (mark && + fsnotify_compare_groups(max_prio_group, mark->group) == 0) + fsnotify_iter_set_report_type(iter_info, type); + } + + return iter_info->report_mask; +} + +/* + * Pop from iter_info multi head queue, the marks that were iterated in the + * current iteration step. + */ +static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info) +{ + int type; + + fsnotify_foreach_obj_type(type) { + if (fsnotify_iter_should_report_type(iter_info, type)) + iter_info->marks[type] = + fsnotify_next_mark(iter_info->marks[type]); + } +} + +/* + * fsnotify - This is the main call to fsnotify. + * + * The VFS calls into hook specific functions in linux/fsnotify.h. + * Those functions then in turn call here. Here will call out to all of the + * registered fsnotify_group. Those groups can then use the notification event + * in whatever means they feel necessary. + * + * @mask: event type and flags + * @data: object that event happened on + * @data_type: type of object for fanotify_data_XXX() accessors + * @dir: optional directory associated with event - + * if @file_name is not NULL, this is the directory that + * @file_name is relative to + * @file_name: optional file name associated with event + * @inode: optional inode associated with event - + * either @dir or @inode must be non-NULL. + * if both are non-NULL event may be reported to both. + * @cookie: inotify rename cookie + */ +int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, + const struct qstr *file_name, struct inode *inode, u32 cookie) +{ + const struct path *path = fsnotify_data_path(data, data_type); + struct fsnotify_iter_info iter_info = {}; + struct super_block *sb; + struct mount *mnt = NULL; + struct inode *parent = NULL; + int ret = 0; + __u32 test_mask, marks_mask; + + if (path) + mnt = real_mount(path->mnt); + + if (!inode) { + /* Dirent event - report on TYPE_INODE to dir */ + inode = dir; + } else if (mask & FS_EVENT_ON_CHILD) { + /* + * Event on child - report on TYPE_PARENT to dir if it is + * watching children and on TYPE_INODE to child. + */ + parent = dir; + } + sb = inode->i_sb; + + /* + * Optimization: srcu_read_lock() has a memory barrier which can + * be expensive. It protects walking the *_fsnotify_marks lists. + * However, if we do not walk the lists, we do not have to do + * SRCU because we have no references to any objects and do not + * need SRCU to keep them "alive". + */ + if (!sb->s_fsnotify_marks && + (!mnt || !mnt->mnt_fsnotify_marks) && + (!inode || !inode->i_fsnotify_marks) && + (!parent || !parent->i_fsnotify_marks)) + return 0; + + marks_mask = sb->s_fsnotify_mask; + if (mnt) + marks_mask |= mnt->mnt_fsnotify_mask; + if (inode) + marks_mask |= inode->i_fsnotify_mask; + if (parent) + marks_mask |= parent->i_fsnotify_mask; + + + /* + * if this is a modify event we may need to clear the ignored masks + * otherwise return if none of the marks care about this type of event. + */ + test_mask = (mask & ALL_FSNOTIFY_EVENTS); + if (!(mask & FS_MODIFY) && !(test_mask & marks_mask)) + return 0; + + iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu); + + iter_info.marks[FSNOTIFY_OBJ_TYPE_SB] = + fsnotify_first_mark(&sb->s_fsnotify_marks); + if (mnt) { + iter_info.marks[FSNOTIFY_OBJ_TYPE_VFSMOUNT] = + fsnotify_first_mark(&mnt->mnt_fsnotify_marks); + } + if (inode) { + iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] = + fsnotify_first_mark(&inode->i_fsnotify_marks); + } + if (parent) { + iter_info.marks[FSNOTIFY_OBJ_TYPE_PARENT] = + fsnotify_first_mark(&parent->i_fsnotify_marks); + } + + /* + * We need to merge inode/vfsmount/sb mark lists so that e.g. inode mark + * ignore masks are properly reflected for mount/sb mark notifications. + * That's why this traversal is so complicated... + */ + while (fsnotify_iter_select_report_types(&iter_info)) { + ret = send_to_group(mask, data, data_type, dir, file_name, + cookie, &iter_info); + + if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS)) + goto out; + + fsnotify_iter_next(&iter_info); + } + ret = 0; +out: + srcu_read_unlock(&fsnotify_mark_srcu, iter_info.srcu_idx); + + return ret; +} +EXPORT_SYMBOL_GPL(fsnotify); + +static __init int fsnotify_init(void) +{ + int ret; + + BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 25); + + ret = init_srcu_struct(&fsnotify_mark_srcu); + if (ret) + panic("initializing fsnotify_mark_srcu"); + + fsnotify_mark_connector_cachep = KMEM_CACHE(fsnotify_mark_connector, + SLAB_PANIC); + + return 0; +} +core_initcall(fsnotify_init); diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h new file mode 100644 index 000000000..ff2063ec6 --- /dev/null +++ b/fs/notify/fsnotify.h @@ -0,0 +1,70 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __FS_NOTIFY_FSNOTIFY_H_ +#define __FS_NOTIFY_FSNOTIFY_H_ + +#include <linux/list.h> +#include <linux/fsnotify.h> +#include <linux/srcu.h> +#include <linux/types.h> + +#include "../mount.h" + +static inline struct inode *fsnotify_conn_inode( + struct fsnotify_mark_connector *conn) +{ + return container_of(conn->obj, struct inode, i_fsnotify_marks); +} + +static inline struct mount *fsnotify_conn_mount( + struct fsnotify_mark_connector *conn) +{ + return container_of(conn->obj, struct mount, mnt_fsnotify_marks); +} + +static inline struct super_block *fsnotify_conn_sb( + struct fsnotify_mark_connector *conn) +{ + return container_of(conn->obj, struct super_block, s_fsnotify_marks); +} + +/* destroy all events sitting in this groups notification queue */ +extern void fsnotify_flush_notify(struct fsnotify_group *group); + +/* protects reads of inode and vfsmount marks list */ +extern struct srcu_struct fsnotify_mark_srcu; + +/* compare two groups for sorting of marks lists */ +extern int fsnotify_compare_groups(struct fsnotify_group *a, + struct fsnotify_group *b); + +/* Destroy all marks attached to an object via connector */ +extern void fsnotify_destroy_marks(fsnotify_connp_t *connp); +/* run the list of all marks associated with inode and destroy them */ +static inline void fsnotify_clear_marks_by_inode(struct inode *inode) +{ + fsnotify_destroy_marks(&inode->i_fsnotify_marks); +} +/* run the list of all marks associated with vfsmount and destroy them */ +static inline void fsnotify_clear_marks_by_mount(struct vfsmount *mnt) +{ + fsnotify_destroy_marks(&real_mount(mnt)->mnt_fsnotify_marks); +} +/* run the list of all marks associated with sb and destroy them */ +static inline void fsnotify_clear_marks_by_sb(struct super_block *sb) +{ + fsnotify_destroy_marks(&sb->s_fsnotify_marks); +} + +/* + * update the dentry->d_flags of all of inode's children to indicate if inode cares + * about events that happen to its children. + */ +extern void __fsnotify_update_child_dentry_flags(struct inode *inode); + +/* allocate and destroy and event holder to attach events to notification/access queues */ +extern struct fsnotify_event_holder *fsnotify_alloc_event_holder(void); +extern void fsnotify_destroy_event_holder(struct fsnotify_event_holder *holder); + +extern struct kmem_cache *fsnotify_mark_connector_cachep; + +#endif /* __FS_NOTIFY_FSNOTIFY_H_ */ diff --git a/fs/notify/group.c b/fs/notify/group.c new file mode 100644 index 000000000..a4a4b1c64 --- /dev/null +++ b/fs/notify/group.c @@ -0,0 +1,149 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + */ + +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/srcu.h> +#include <linux/rculist.h> +#include <linux/wait.h> +#include <linux/memcontrol.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +#include <linux/atomic.h> + +/* + * Final freeing of a group + */ +static void fsnotify_final_destroy_group(struct fsnotify_group *group) +{ + if (group->ops->free_group_priv) + group->ops->free_group_priv(group); + + mem_cgroup_put(group->memcg); + mutex_destroy(&group->mark_mutex); + + kfree(group); +} + +/* + * Stop queueing new events for this group. Once this function returns + * fsnotify_add_event() will not add any new events to the group's queue. + */ +void fsnotify_group_stop_queueing(struct fsnotify_group *group) +{ + spin_lock(&group->notification_lock); + group->shutdown = true; + spin_unlock(&group->notification_lock); +} + +/* + * Trying to get rid of a group. Remove all marks, flush all events and release + * the group reference. + * Note that another thread calling fsnotify_clear_marks_by_group() may still + * hold a ref to the group. + */ +void fsnotify_destroy_group(struct fsnotify_group *group) +{ + /* + * Stop queueing new events. The code below is careful enough to not + * require this but fanotify needs to stop queuing events even before + * fsnotify_destroy_group() is called and this makes the other callers + * of fsnotify_destroy_group() to see the same behavior. + */ + fsnotify_group_stop_queueing(group); + + /* Clear all marks for this group and queue them for destruction */ + fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_ALL_TYPES_MASK); + + /* + * Some marks can still be pinned when waiting for response from + * userspace. Wait for those now. fsnotify_prepare_user_wait() will + * not succeed now so this wait is race-free. + */ + wait_event(group->notification_waitq, !atomic_read(&group->user_waits)); + + /* + * Wait until all marks get really destroyed. We could actually destroy + * them ourselves instead of waiting for worker to do it, however that + * would be racy as worker can already be processing some marks before + * we even entered fsnotify_destroy_group(). + */ + fsnotify_wait_marks_destroyed(); + + /* + * Since we have waited for fsnotify_mark_srcu in + * fsnotify_mark_destroy_list() there can be no outstanding event + * notification against this group. So clearing the notification queue + * of all events is reliable now. + */ + fsnotify_flush_notify(group); + + /* + * Destroy overflow event (we cannot use fsnotify_destroy_event() as + * that deliberately ignores overflow events. + */ + if (group->overflow_event) + group->ops->free_event(group->overflow_event); + + fsnotify_put_group(group); +} + +/* + * Get reference to a group. + */ +void fsnotify_get_group(struct fsnotify_group *group) +{ + refcount_inc(&group->refcnt); +} + +/* + * Drop a reference to a group. Free it if it's through. + */ +void fsnotify_put_group(struct fsnotify_group *group) +{ + if (refcount_dec_and_test(&group->refcnt)) + fsnotify_final_destroy_group(group); +} +EXPORT_SYMBOL_GPL(fsnotify_put_group); + +/* + * Create a new fsnotify_group and hold a reference for the group returned. + */ +struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) +{ + struct fsnotify_group *group; + + group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); + if (!group) + return ERR_PTR(-ENOMEM); + + /* set to 0 when there a no external references to this group */ + refcount_set(&group->refcnt, 1); + atomic_set(&group->num_marks, 0); + atomic_set(&group->user_waits, 0); + + spin_lock_init(&group->notification_lock); + INIT_LIST_HEAD(&group->notification_list); + init_waitqueue_head(&group->notification_waitq); + group->max_events = UINT_MAX; + + mutex_init(&group->mark_mutex); + INIT_LIST_HEAD(&group->marks_list); + + group->ops = ops; + + return group; +} +EXPORT_SYMBOL_GPL(fsnotify_alloc_group); + +int fsnotify_fasync(int fd, struct file *file, int on) +{ + struct fsnotify_group *group = file->private_data; + + return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO; +} diff --git a/fs/notify/inotify/Kconfig b/fs/notify/inotify/Kconfig new file mode 100644 index 000000000..1cc8be25d --- /dev/null +++ b/fs/notify/inotify/Kconfig @@ -0,0 +1,17 @@ +# SPDX-License-Identifier: GPL-2.0-only +config INOTIFY_USER + bool "Inotify support for userspace" + select FSNOTIFY + default y + help + Say Y here to enable inotify support for userspace, including the + associated system calls. Inotify allows monitoring of both files and + directories via a single open fd. Events are read from the file + descriptor, which is also select()- and poll()-able. + Inotify fixes numerous shortcomings in dnotify and introduces several + new features including multiple file events, one-shot support, and + unmount notification. + + For more information, see <file:Documentation/filesystems/inotify.rst> + + If unsure, say Y. diff --git a/fs/notify/inotify/Makefile b/fs/notify/inotify/Makefile new file mode 100644 index 000000000..812237eec --- /dev/null +++ b/fs/notify/inotify/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_INOTIFY_USER) += inotify_fsnotify.o inotify_user.o diff --git a/fs/notify/inotify/inotify.h b/fs/notify/inotify/inotify.h new file mode 100644 index 000000000..8f00151eb --- /dev/null +++ b/fs/notify/inotify/inotify.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/fsnotify_backend.h> +#include <linux/inotify.h> +#include <linux/slab.h> /* struct kmem_cache */ + +struct inotify_event_info { + struct fsnotify_event fse; + u32 mask; + int wd; + u32 sync_cookie; + int name_len; + char name[]; +}; + +struct inotify_inode_mark { + struct fsnotify_mark fsn_mark; + int wd; +}; + +static inline struct inotify_event_info *INOTIFY_E(struct fsnotify_event *fse) +{ + return container_of(fse, struct inotify_event_info, fse); +} + +/* + * INOTIFY_USER_FLAGS represents all of the mask bits that we expose to + * userspace. There is at least one bit (FS_EVENT_ON_CHILD) which is + * used only internally to the kernel. + */ +#define INOTIFY_USER_MASK (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK) + +static inline __u32 inotify_mark_user_mask(struct fsnotify_mark *fsn_mark) +{ + return fsn_mark->mask & INOTIFY_USER_MASK; +} + +extern void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark, + struct fsnotify_group *group); +extern int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, + u32 mask, struct inode *inode, + struct inode *dir, + const struct qstr *name, u32 cookie); + +extern const struct fsnotify_ops inotify_fsnotify_ops; +extern struct kmem_cache *inotify_inode_mark_cachep; + +#ifdef CONFIG_INOTIFY_USER +static inline void dec_inotify_instances(struct ucounts *ucounts) +{ + dec_ucount(ucounts, UCOUNT_INOTIFY_INSTANCES); +} + +static inline struct ucounts *inc_inotify_watches(struct ucounts *ucounts) +{ + return inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_INOTIFY_WATCHES); +} + +static inline void dec_inotify_watches(struct ucounts *ucounts) +{ + dec_ucount(ucounts, UCOUNT_INOTIFY_WATCHES); +} +#endif diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c new file mode 100644 index 000000000..66991c7fe --- /dev/null +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -0,0 +1,207 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * fs/inotify_user.c - inotify support for userspace + * + * Authors: + * John McCutchan <ttb@tentacle.dhs.org> + * Robert Love <rml@novell.com> + * + * Copyright (C) 2005 John McCutchan + * Copyright 2006 Hewlett-Packard Development Company, L.P. + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * inotify was largely rewriten to make use of the fsnotify infrastructure + */ + +#include <linux/dcache.h> /* d_unlinked */ +#include <linux/fs.h> /* struct inode */ +#include <linux/fsnotify_backend.h> +#include <linux/inotify.h> +#include <linux/path.h> /* struct path */ +#include <linux/slab.h> /* kmem_* */ +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/sched/user.h> +#include <linux/sched/mm.h> + +#include "inotify.h" + +/* + * Check if 2 events contain the same information. + */ +static bool event_compare(struct fsnotify_event *old_fsn, + struct fsnotify_event *new_fsn) +{ + struct inotify_event_info *old, *new; + + old = INOTIFY_E(old_fsn); + new = INOTIFY_E(new_fsn); + if (old->mask & FS_IN_IGNORED) + return false; + if ((old->mask == new->mask) && + (old->wd == new->wd) && + (old->name_len == new->name_len) && + (!old->name_len || !strcmp(old->name, new->name))) + return true; + return false; +} + +static int inotify_merge(struct list_head *list, + struct fsnotify_event *event) +{ + struct fsnotify_event *last_event; + + last_event = list_entry(list->prev, struct fsnotify_event, list); + return event_compare(last_event, event); +} + +int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask, + struct inode *inode, struct inode *dir, + const struct qstr *name, u32 cookie) +{ + struct inotify_inode_mark *i_mark; + struct inotify_event_info *event; + struct fsnotify_event *fsn_event; + struct fsnotify_group *group = inode_mark->group; + int ret; + int len = 0, wd; + int alloc_len = sizeof(struct inotify_event_info); + struct mem_cgroup *old_memcg; + + if (name) { + len = name->len; + alloc_len += len + 1; + } + + pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark, + mask); + + i_mark = container_of(inode_mark, struct inotify_inode_mark, + fsn_mark); + + /* + * We can be racing with mark being detached. Don't report event with + * invalid wd. + */ + wd = READ_ONCE(i_mark->wd); + if (wd == -1) + return 0; + /* + * Whoever is interested in the event, pays for the allocation. Do not + * trigger OOM killer in the target monitoring memcg as it may have + * security repercussion. + */ + old_memcg = set_active_memcg(group->memcg); + event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL); + set_active_memcg(old_memcg); + + if (unlikely(!event)) { + /* + * Treat lost event due to ENOMEM the same way as queue + * overflow to let userspace know event was lost. + */ + fsnotify_queue_overflow(group); + return -ENOMEM; + } + + /* + * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events + * for fanotify. inotify never reported IN_ISDIR with those events. + * It looks like an oversight, but to avoid the risk of breaking + * existing inotify programs, mask the flag out from those events. + */ + if (mask & (IN_MOVE_SELF | IN_DELETE_SELF)) + mask &= ~IN_ISDIR; + + fsn_event = &event->fse; + fsnotify_init_event(fsn_event, 0); + event->mask = mask; + event->wd = wd; + event->sync_cookie = cookie; + event->name_len = len; + if (len) + strcpy(event->name, name->name); + + ret = fsnotify_add_event(group, fsn_event, inotify_merge); + if (ret) { + /* Our event wasn't used in the end. Free it. */ + fsnotify_destroy_event(group, fsn_event); + } + + if (inode_mark->mask & IN_ONESHOT) + fsnotify_destroy_mark(inode_mark, group); + + return 0; +} + +static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group) +{ + inotify_ignored_and_remove_idr(fsn_mark, group); +} + +/* + * This is NEVER supposed to be called. Inotify marks should either have been + * removed from the idr when the watch was removed or in the + * fsnotify_destroy_mark_by_group() call when the inotify instance was being + * torn down. This is only called if the idr is about to be freed but there + * are still marks in it. + */ +static int idr_callback(int id, void *p, void *data) +{ + struct fsnotify_mark *fsn_mark; + struct inotify_inode_mark *i_mark; + static bool warned = false; + + if (warned) + return 0; + + warned = true; + fsn_mark = p; + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + + WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in " + "idr. Probably leaking memory\n", id, p, data); + + /* + * I'm taking the liberty of assuming that the mark in question is a + * valid address and I'm dereferencing it. This might help to figure + * out why we got here and the panic is no worse than the original + * BUG() that was here. + */ + if (fsn_mark) + printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n", + fsn_mark->group, i_mark->wd); + return 0; +} + +static void inotify_free_group_priv(struct fsnotify_group *group) +{ + /* ideally the idr is empty and we won't hit the BUG in the callback */ + idr_for_each(&group->inotify_data.idr, idr_callback, group); + idr_destroy(&group->inotify_data.idr); + if (group->inotify_data.ucounts) + dec_inotify_instances(group->inotify_data.ucounts); +} + +static void inotify_free_event(struct fsnotify_event *fsn_event) +{ + kfree(INOTIFY_E(fsn_event)); +} + +/* ding dong the mark is dead */ +static void inotify_free_mark(struct fsnotify_mark *fsn_mark) +{ + struct inotify_inode_mark *i_mark; + + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + + kmem_cache_free(inotify_inode_mark_cachep, i_mark); +} + +const struct fsnotify_ops inotify_fsnotify_ops = { + .handle_inode_event = inotify_handle_inode_event, + .free_group_priv = inotify_free_group_priv, + .free_event = inotify_free_event, + .freeing_mark = inotify_freeing_mark, + .free_mark = inotify_free_mark, +}; diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c new file mode 100644 index 000000000..32b6b9702 --- /dev/null +++ b/fs/notify/inotify/inotify_user.c @@ -0,0 +1,830 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * fs/inotify_user.c - inotify support for userspace + * + * Authors: + * John McCutchan <ttb@tentacle.dhs.org> + * Robert Love <rml@novell.com> + * + * Copyright (C) 2005 John McCutchan + * Copyright 2006 Hewlett-Packard Development Company, L.P. + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * inotify was largely rewriten to make use of the fsnotify infrastructure + */ + +#include <linux/file.h> +#include <linux/fs.h> /* struct inode */ +#include <linux/fsnotify_backend.h> +#include <linux/idr.h> +#include <linux/init.h> /* fs_initcall */ +#include <linux/inotify.h> +#include <linux/kernel.h> /* roundup() */ +#include <linux/namei.h> /* LOOKUP_FOLLOW */ +#include <linux/sched/signal.h> +#include <linux/slab.h> /* struct kmem_cache */ +#include <linux/syscalls.h> +#include <linux/types.h> +#include <linux/anon_inodes.h> +#include <linux/uaccess.h> +#include <linux/poll.h> +#include <linux/wait.h> +#include <linux/memcontrol.h> +#include <linux/security.h> + +#include "inotify.h" +#include "../fdinfo.h" + +#include <asm/ioctls.h> + +/* configurable via /proc/sys/fs/inotify/ */ +static int inotify_max_queued_events __read_mostly; + +struct kmem_cache *inotify_inode_mark_cachep __read_mostly; + +#ifdef CONFIG_SYSCTL + +#include <linux/sysctl.h> + +struct ctl_table inotify_table[] = { + { + .procname = "max_user_instances", + .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES], + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + }, + { + .procname = "max_user_watches", + .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES], + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + }, + { + .procname = "max_queued_events", + .data = &inotify_max_queued_events, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO + }, + { } +}; +#endif /* CONFIG_SYSCTL */ + +static inline __u32 inotify_arg_to_mask(struct inode *inode, u32 arg) +{ + __u32 mask; + + /* + * Everything should accept their own ignored and should receive events + * when the inode is unmounted. All directories care about children. + */ + mask = (FS_IN_IGNORED | FS_UNMOUNT); + if (S_ISDIR(inode->i_mode)) + mask |= FS_EVENT_ON_CHILD; + + /* mask off the flags used to open the fd */ + mask |= (arg & INOTIFY_USER_MASK); + + return mask; +} + +static inline u32 inotify_mask_to_arg(__u32 mask) +{ + return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | + IN_Q_OVERFLOW); +} + +/* intofiy userspace file descriptor functions */ +static __poll_t inotify_poll(struct file *file, poll_table *wait) +{ + struct fsnotify_group *group = file->private_data; + __poll_t ret = 0; + + poll_wait(file, &group->notification_waitq, wait); + spin_lock(&group->notification_lock); + if (!fsnotify_notify_queue_is_empty(group)) + ret = EPOLLIN | EPOLLRDNORM; + spin_unlock(&group->notification_lock); + + return ret; +} + +static int round_event_name_len(struct fsnotify_event *fsn_event) +{ + struct inotify_event_info *event; + + event = INOTIFY_E(fsn_event); + if (!event->name_len) + return 0; + return roundup(event->name_len + 1, sizeof(struct inotify_event)); +} + +/* + * Get an inotify_kernel_event if one exists and is small + * enough to fit in "count". Return an error pointer if + * not large enough. + * + * Called with the group->notification_lock held. + */ +static struct fsnotify_event *get_one_event(struct fsnotify_group *group, + size_t count) +{ + size_t event_size = sizeof(struct inotify_event); + struct fsnotify_event *event; + + if (fsnotify_notify_queue_is_empty(group)) + return NULL; + + event = fsnotify_peek_first_event(group); + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + event_size += round_event_name_len(event); + if (event_size > count) + return ERR_PTR(-EINVAL); + + /* held the notification_lock the whole time, so this is the + * same event we peeked above */ + fsnotify_remove_first_event(group); + + return event; +} + +/* + * Copy an event to user space, returning how much we copied. + * + * We already checked that the event size is smaller than the + * buffer we had in "get_one_event()" above. + */ +static ssize_t copy_event_to_user(struct fsnotify_group *group, + struct fsnotify_event *fsn_event, + char __user *buf) +{ + struct inotify_event inotify_event; + struct inotify_event_info *event; + size_t event_size = sizeof(struct inotify_event); + size_t name_len; + size_t pad_name_len; + + pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event); + + event = INOTIFY_E(fsn_event); + name_len = event->name_len; + /* + * round up name length so it is a multiple of event_size + * plus an extra byte for the terminating '\0'. + */ + pad_name_len = round_event_name_len(fsn_event); + inotify_event.len = pad_name_len; + inotify_event.mask = inotify_mask_to_arg(event->mask); + inotify_event.wd = event->wd; + inotify_event.cookie = event->sync_cookie; + + /* send the main event */ + if (copy_to_user(buf, &inotify_event, event_size)) + return -EFAULT; + + buf += event_size; + + /* + * fsnotify only stores the pathname, so here we have to send the pathname + * and then pad that pathname out to a multiple of sizeof(inotify_event) + * with zeros. + */ + if (pad_name_len) { + /* copy the path name */ + if (copy_to_user(buf, event->name, name_len)) + return -EFAULT; + buf += name_len; + + /* fill userspace with 0's */ + if (clear_user(buf, pad_name_len - name_len)) + return -EFAULT; + event_size += pad_name_len; + } + + return event_size; +} + +static ssize_t inotify_read(struct file *file, char __user *buf, + size_t count, loff_t *pos) +{ + struct fsnotify_group *group; + struct fsnotify_event *kevent; + char __user *start; + int ret; + DEFINE_WAIT_FUNC(wait, woken_wake_function); + + start = buf; + group = file->private_data; + + add_wait_queue(&group->notification_waitq, &wait); + while (1) { + spin_lock(&group->notification_lock); + kevent = get_one_event(group, count); + spin_unlock(&group->notification_lock); + + pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent); + + if (kevent) { + ret = PTR_ERR(kevent); + if (IS_ERR(kevent)) + break; + ret = copy_event_to_user(group, kevent, buf); + fsnotify_destroy_event(group, kevent); + if (ret < 0) + break; + buf += ret; + count -= ret; + continue; + } + + ret = -EAGAIN; + if (file->f_flags & O_NONBLOCK) + break; + ret = -ERESTARTSYS; + if (signal_pending(current)) + break; + + if (start != buf) + break; + + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + } + remove_wait_queue(&group->notification_waitq, &wait); + + if (start != buf && ret != -EFAULT) + ret = buf - start; + return ret; +} + +static int inotify_release(struct inode *ignored, struct file *file) +{ + struct fsnotify_group *group = file->private_data; + + pr_debug("%s: group=%p\n", __func__, group); + + /* free this group, matching get was inotify_init->fsnotify_obtain_group */ + fsnotify_destroy_group(group); + + return 0; +} + +static long inotify_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct fsnotify_group *group; + struct fsnotify_event *fsn_event; + void __user *p; + int ret = -ENOTTY; + size_t send_len = 0; + + group = file->private_data; + p = (void __user *) arg; + + pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd); + + switch (cmd) { + case FIONREAD: + spin_lock(&group->notification_lock); + list_for_each_entry(fsn_event, &group->notification_list, + list) { + send_len += sizeof(struct inotify_event); + send_len += round_event_name_len(fsn_event); + } + spin_unlock(&group->notification_lock); + ret = put_user(send_len, (int __user *) p); + break; +#ifdef CONFIG_CHECKPOINT_RESTORE + case INOTIFY_IOC_SETNEXTWD: + ret = -EINVAL; + if (arg >= 1 && arg <= INT_MAX) { + struct inotify_group_private_data *data; + + data = &group->inotify_data; + spin_lock(&data->idr_lock); + idr_set_cursor(&data->idr, (unsigned int)arg); + spin_unlock(&data->idr_lock); + ret = 0; + } + break; +#endif /* CONFIG_CHECKPOINT_RESTORE */ + } + + return ret; +} + +static const struct file_operations inotify_fops = { + .show_fdinfo = inotify_show_fdinfo, + .poll = inotify_poll, + .read = inotify_read, + .fasync = fsnotify_fasync, + .release = inotify_release, + .unlocked_ioctl = inotify_ioctl, + .compat_ioctl = inotify_ioctl, + .llseek = noop_llseek, +}; + + +/* + * find_inode - resolve a user-given path to a specific inode + */ +static int inotify_find_inode(const char __user *dirname, struct path *path, + unsigned int flags, __u64 mask) +{ + int error; + + error = user_path_at(AT_FDCWD, dirname, flags, path); + if (error) + return error; + /* you can only watch an inode if you have read permissions on it */ + error = inode_permission(path->dentry->d_inode, MAY_READ); + if (error) { + path_put(path); + return error; + } + error = security_path_notify(path, mask, + FSNOTIFY_OBJ_TYPE_INODE); + if (error) + path_put(path); + + return error; +} + +static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock, + struct inotify_inode_mark *i_mark) +{ + int ret; + + idr_preload(GFP_KERNEL); + spin_lock(idr_lock); + + ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT); + if (ret >= 0) { + /* we added the mark to the idr, take a reference */ + i_mark->wd = ret; + fsnotify_get_mark(&i_mark->fsn_mark); + } + + spin_unlock(idr_lock); + idr_preload_end(); + return ret < 0 ? ret : 0; +} + +static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group, + int wd) +{ + struct idr *idr = &group->inotify_data.idr; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + struct inotify_inode_mark *i_mark; + + assert_spin_locked(idr_lock); + + i_mark = idr_find(idr, wd); + if (i_mark) { + struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark; + + fsnotify_get_mark(fsn_mark); + /* One ref for being in the idr, one ref we just took */ + BUG_ON(refcount_read(&fsn_mark->refcnt) < 2); + } + + return i_mark; +} + +static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group, + int wd) +{ + struct inotify_inode_mark *i_mark; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + + spin_lock(idr_lock); + i_mark = inotify_idr_find_locked(group, wd); + spin_unlock(idr_lock); + + return i_mark; +} + +/* + * Remove the mark from the idr (if present) and drop the reference + * on the mark because it was in the idr. + */ +static void inotify_remove_from_idr(struct fsnotify_group *group, + struct inotify_inode_mark *i_mark) +{ + struct idr *idr = &group->inotify_data.idr; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + struct inotify_inode_mark *found_i_mark = NULL; + int wd; + + spin_lock(idr_lock); + wd = i_mark->wd; + + /* + * does this i_mark think it is in the idr? we shouldn't get called + * if it wasn't.... + */ + if (wd == -1) { + WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n", + __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group); + goto out; + } + + /* Lets look in the idr to see if we find it */ + found_i_mark = inotify_idr_find_locked(group, wd); + if (unlikely(!found_i_mark)) { + WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n", + __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group); + goto out; + } + + /* + * We found an mark in the idr at the right wd, but it's + * not the mark we were told to remove. eparis seriously + * fucked up somewhere. + */ + if (unlikely(found_i_mark != i_mark)) { + WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p " + "found_i_mark=%p found_i_mark->wd=%d " + "found_i_mark->group=%p\n", __func__, i_mark, + i_mark->wd, i_mark->fsn_mark.group, found_i_mark, + found_i_mark->wd, found_i_mark->fsn_mark.group); + goto out; + } + + /* + * One ref for being in the idr + * one ref grabbed by inotify_idr_find + */ + if (unlikely(refcount_read(&i_mark->fsn_mark.refcnt) < 2)) { + printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n", + __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group); + /* we can't really recover with bad ref cnting.. */ + BUG(); + } + + idr_remove(idr, wd); + /* Removed from the idr, drop that ref. */ + fsnotify_put_mark(&i_mark->fsn_mark); +out: + i_mark->wd = -1; + spin_unlock(idr_lock); + /* match the ref taken by inotify_idr_find_locked() */ + if (found_i_mark) + fsnotify_put_mark(&found_i_mark->fsn_mark); +} + +/* + * Send IN_IGNORED for this wd, remove this wd from the idr. + */ +void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark, + struct fsnotify_group *group) +{ + struct inotify_inode_mark *i_mark; + + /* Queue ignore event for the watch */ + inotify_handle_inode_event(fsn_mark, FS_IN_IGNORED, NULL, NULL, NULL, + 0); + + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + /* remove this mark from the idr */ + inotify_remove_from_idr(group, i_mark); + + dec_inotify_watches(group->inotify_data.ucounts); +} + +static int inotify_update_existing_watch(struct fsnotify_group *group, + struct inode *inode, + u32 arg) +{ + struct fsnotify_mark *fsn_mark; + struct inotify_inode_mark *i_mark; + __u32 old_mask, new_mask; + __u32 mask; + int add = (arg & IN_MASK_ADD); + int create = (arg & IN_MASK_CREATE); + int ret; + + mask = inotify_arg_to_mask(inode, arg); + + fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group); + if (!fsn_mark) + return -ENOENT; + else if (create) { + ret = -EEXIST; + goto out; + } + + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + + spin_lock(&fsn_mark->lock); + old_mask = fsn_mark->mask; + if (add) + fsn_mark->mask |= mask; + else + fsn_mark->mask = mask; + new_mask = fsn_mark->mask; + spin_unlock(&fsn_mark->lock); + + if (old_mask != new_mask) { + /* more bits in old than in new? */ + int dropped = (old_mask & ~new_mask); + /* more bits in this fsn_mark than the inode's mask? */ + int do_inode = (new_mask & ~inode->i_fsnotify_mask); + + /* update the inode with this new fsn_mark */ + if (dropped || do_inode) + fsnotify_recalc_mask(inode->i_fsnotify_marks); + + } + + /* return the wd */ + ret = i_mark->wd; + +out: + /* match the get from fsnotify_find_mark() */ + fsnotify_put_mark(fsn_mark); + + return ret; +} + +static int inotify_new_watch(struct fsnotify_group *group, + struct inode *inode, + u32 arg) +{ + struct inotify_inode_mark *tmp_i_mark; + __u32 mask; + int ret; + struct idr *idr = &group->inotify_data.idr; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + + mask = inotify_arg_to_mask(inode, arg); + + tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); + if (unlikely(!tmp_i_mark)) + return -ENOMEM; + + fsnotify_init_mark(&tmp_i_mark->fsn_mark, group); + tmp_i_mark->fsn_mark.mask = mask; + tmp_i_mark->wd = -1; + + ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark); + if (ret) + goto out_err; + + /* increment the number of watches the user has */ + if (!inc_inotify_watches(group->inotify_data.ucounts)) { + inotify_remove_from_idr(group, tmp_i_mark); + ret = -ENOSPC; + goto out_err; + } + + /* we are on the idr, now get on the inode */ + ret = fsnotify_add_inode_mark_locked(&tmp_i_mark->fsn_mark, inode, 0); + if (ret) { + /* we failed to get on the inode, get off the idr */ + inotify_remove_from_idr(group, tmp_i_mark); + goto out_err; + } + + + /* return the watch descriptor for this new mark */ + ret = tmp_i_mark->wd; + +out_err: + /* match the ref from fsnotify_init_mark() */ + fsnotify_put_mark(&tmp_i_mark->fsn_mark); + + return ret; +} + +static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) +{ + int ret = 0; + + mutex_lock(&group->mark_mutex); + /* try to update and existing watch with the new arg */ + ret = inotify_update_existing_watch(group, inode, arg); + /* no mark present, try to add a new one */ + if (ret == -ENOENT) + ret = inotify_new_watch(group, inode, arg); + mutex_unlock(&group->mark_mutex); + + return ret; +} + +static struct fsnotify_group *inotify_new_group(unsigned int max_events) +{ + struct fsnotify_group *group; + struct inotify_event_info *oevent; + + group = fsnotify_alloc_group(&inotify_fsnotify_ops); + if (IS_ERR(group)) + return group; + + oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL); + if (unlikely(!oevent)) { + fsnotify_destroy_group(group); + return ERR_PTR(-ENOMEM); + } + group->overflow_event = &oevent->fse; + fsnotify_init_event(group->overflow_event, 0); + oevent->mask = FS_Q_OVERFLOW; + oevent->wd = -1; + oevent->sync_cookie = 0; + oevent->name_len = 0; + + group->max_events = max_events; + group->memcg = get_mem_cgroup_from_mm(current->mm); + + spin_lock_init(&group->inotify_data.idr_lock); + idr_init(&group->inotify_data.idr); + group->inotify_data.ucounts = inc_ucount(current_user_ns(), + current_euid(), + UCOUNT_INOTIFY_INSTANCES); + + if (!group->inotify_data.ucounts) { + fsnotify_destroy_group(group); + return ERR_PTR(-EMFILE); + } + + return group; +} + + +/* inotify syscalls */ +static int do_inotify_init(int flags) +{ + struct fsnotify_group *group; + int ret; + + /* Check the IN_* constants for consistency. */ + BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); + BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); + + if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) + return -EINVAL; + + /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ + group = inotify_new_group(inotify_max_queued_events); + if (IS_ERR(group)) + return PTR_ERR(group); + + ret = anon_inode_getfd("inotify", &inotify_fops, group, + O_RDONLY | flags); + if (ret < 0) + fsnotify_destroy_group(group); + + return ret; +} + +SYSCALL_DEFINE1(inotify_init1, int, flags) +{ + return do_inotify_init(flags); +} + +SYSCALL_DEFINE0(inotify_init) +{ + return do_inotify_init(0); +} + +SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, + u32, mask) +{ + struct fsnotify_group *group; + struct inode *inode; + struct path path; + struct fd f; + int ret; + unsigned flags = 0; + + /* + * We share a lot of code with fs/dnotify. We also share + * the bit layout between inotify's IN_* and the fsnotify + * FS_*. This check ensures that only the inotify IN_* + * bits get passed in and set in watches/events. + */ + if (unlikely(mask & ~ALL_INOTIFY_BITS)) + return -EINVAL; + /* + * Require at least one valid bit set in the mask. + * Without _something_ set, we would have no events to + * watch for. + */ + if (unlikely(!(mask & ALL_INOTIFY_BITS))) + return -EINVAL; + + f = fdget(fd); + if (unlikely(!f.file)) + return -EBADF; + + /* IN_MASK_ADD and IN_MASK_CREATE don't make sense together */ + if (unlikely((mask & IN_MASK_ADD) && (mask & IN_MASK_CREATE))) { + ret = -EINVAL; + goto fput_and_out; + } + + /* verify that this is indeed an inotify instance */ + if (unlikely(f.file->f_op != &inotify_fops)) { + ret = -EINVAL; + goto fput_and_out; + } + + if (!(mask & IN_DONT_FOLLOW)) + flags |= LOOKUP_FOLLOW; + if (mask & IN_ONLYDIR) + flags |= LOOKUP_DIRECTORY; + + ret = inotify_find_inode(pathname, &path, flags, + (mask & IN_ALL_EVENTS)); + if (ret) + goto fput_and_out; + + /* inode held in place by reference to path; group by fget on fd */ + inode = path.dentry->d_inode; + group = f.file->private_data; + + /* create/update an inode mark */ + ret = inotify_update_watch(group, inode, mask); + path_put(&path); +fput_and_out: + fdput(f); + return ret; +} + +SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) +{ + struct fsnotify_group *group; + struct inotify_inode_mark *i_mark; + struct fd f; + int ret = -EINVAL; + + f = fdget(fd); + if (unlikely(!f.file)) + return -EBADF; + + /* verify that this is indeed an inotify instance */ + if (unlikely(f.file->f_op != &inotify_fops)) + goto out; + + group = f.file->private_data; + + i_mark = inotify_idr_find(group, wd); + if (unlikely(!i_mark)) + goto out; + + ret = 0; + + fsnotify_destroy_mark(&i_mark->fsn_mark, group); + + /* match ref taken by inotify_idr_find */ + fsnotify_put_mark(&i_mark->fsn_mark); + +out: + fdput(f); + return ret; +} + +/* + * inotify_user_setup - Our initialization function. Note that we cannot return + * error because we have compiled-in VFS hooks. So an (unlikely) failure here + * must result in panic(). + */ +static int __init inotify_user_setup(void) +{ + BUILD_BUG_ON(IN_ACCESS != FS_ACCESS); + BUILD_BUG_ON(IN_MODIFY != FS_MODIFY); + BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB); + BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE); + BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); + BUILD_BUG_ON(IN_OPEN != FS_OPEN); + BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM); + BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO); + BUILD_BUG_ON(IN_CREATE != FS_CREATE); + BUILD_BUG_ON(IN_DELETE != FS_DELETE); + BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF); + BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF); + BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT); + BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW); + BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED); + BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK); + BUILD_BUG_ON(IN_ISDIR != FS_ISDIR); + BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT); + + BUILD_BUG_ON(HWEIGHT32(ALL_INOTIFY_BITS) != 22); + + inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, + SLAB_PANIC|SLAB_ACCOUNT); + + inotify_max_queued_events = 16384; + init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128; + init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = 8192; + + return 0; +} +fs_initcall(inotify_user_setup); diff --git a/fs/notify/mark.c b/fs/notify/mark.c new file mode 100644 index 000000000..5b44be5f9 --- /dev/null +++ b/fs/notify/mark.c @@ -0,0 +1,849 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + */ + +/* + * fsnotify inode mark locking/lifetime/and refcnting + * + * REFCNT: + * The group->recnt and mark->refcnt tell how many "things" in the kernel + * currently are referencing the objects. Both kind of objects typically will + * live inside the kernel with a refcnt of 2, one for its creation and one for + * the reference a group and a mark hold to each other. + * If you are holding the appropriate locks, you can take a reference and the + * object itself is guaranteed to survive until the reference is dropped. + * + * LOCKING: + * There are 3 locks involved with fsnotify inode marks and they MUST be taken + * in order as follows: + * + * group->mark_mutex + * mark->lock + * mark->connector->lock + * + * group->mark_mutex protects the marks_list anchored inside a given group and + * each mark is hooked via the g_list. It also protects the groups private + * data (i.e group limits). + + * mark->lock protects the marks attributes like its masks and flags. + * Furthermore it protects the access to a reference of the group that the mark + * is assigned to as well as the access to a reference of the inode/vfsmount + * that is being watched by the mark. + * + * mark->connector->lock protects the list of marks anchored inside an + * inode / vfsmount and each mark is hooked via the i_list. + * + * A list of notification marks relating to inode / mnt is contained in + * fsnotify_mark_connector. That structure is alive as long as there are any + * marks in the list and is also protected by fsnotify_mark_srcu. A mark gets + * detached from fsnotify_mark_connector when last reference to the mark is + * dropped. Thus having mark reference is enough to protect mark->connector + * pointer and to make sure fsnotify_mark_connector cannot disappear. Also + * because we remove mark from g_list before dropping mark reference associated + * with that, any mark found through g_list is guaranteed to have + * mark->connector set until we drop group->mark_mutex. + * + * LIFETIME: + * Inode marks survive between when they are added to an inode and when their + * refcnt==0. Marks are also protected by fsnotify_mark_srcu. + * + * The inode mark can be cleared for a number of different reasons including: + * - The inode is unlinked for the last time. (fsnotify_inode_remove) + * - The inode is being evicted from cache. (fsnotify_inode_delete) + * - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes) + * - Something explicitly requests that it be removed. (fsnotify_destroy_mark) + * - The fsnotify_group associated with the mark is going away and all such marks + * need to be cleaned up. (fsnotify_clear_marks_by_group) + * + * This has the very interesting property of being able to run concurrently with + * any (or all) other directions. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/kthread.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/srcu.h> +#include <linux/ratelimit.h> + +#include <linux/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +#define FSNOTIFY_REAPER_DELAY (1) /* 1 jiffy */ + +struct srcu_struct fsnotify_mark_srcu; +struct kmem_cache *fsnotify_mark_connector_cachep; + +static DEFINE_SPINLOCK(destroy_lock); +static LIST_HEAD(destroy_list); +static struct fsnotify_mark_connector *connector_destroy_list; + +static void fsnotify_mark_destroy_workfn(struct work_struct *work); +static DECLARE_DELAYED_WORK(reaper_work, fsnotify_mark_destroy_workfn); + +static void fsnotify_connector_destroy_workfn(struct work_struct *work); +static DECLARE_WORK(connector_reaper_work, fsnotify_connector_destroy_workfn); + +void fsnotify_get_mark(struct fsnotify_mark *mark) +{ + WARN_ON_ONCE(!refcount_read(&mark->refcnt)); + refcount_inc(&mark->refcnt); +} + +static __u32 *fsnotify_conn_mask_p(struct fsnotify_mark_connector *conn) +{ + if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) + return &fsnotify_conn_inode(conn)->i_fsnotify_mask; + else if (conn->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) + return &fsnotify_conn_mount(conn)->mnt_fsnotify_mask; + else if (conn->type == FSNOTIFY_OBJ_TYPE_SB) + return &fsnotify_conn_sb(conn)->s_fsnotify_mask; + return NULL; +} + +__u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn) +{ + if (WARN_ON(!fsnotify_valid_obj_type(conn->type))) + return 0; + + return *fsnotify_conn_mask_p(conn); +} + +static void __fsnotify_recalc_mask(struct fsnotify_mark_connector *conn) +{ + u32 new_mask = 0; + struct fsnotify_mark *mark; + + assert_spin_locked(&conn->lock); + /* We can get detached connector here when inode is getting unlinked. */ + if (!fsnotify_valid_obj_type(conn->type)) + return; + hlist_for_each_entry(mark, &conn->list, obj_list) { + if (mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) + new_mask |= mark->mask; + } + *fsnotify_conn_mask_p(conn) = new_mask; +} + +/* + * Calculate mask of events for a list of marks. The caller must make sure + * connector and connector->obj cannot disappear under us. Callers achieve + * this by holding a mark->lock or mark->group->mark_mutex for a mark on this + * list. + */ +void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn) +{ + if (!conn) + return; + + spin_lock(&conn->lock); + __fsnotify_recalc_mask(conn); + spin_unlock(&conn->lock); + if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) + __fsnotify_update_child_dentry_flags( + fsnotify_conn_inode(conn)); +} + +/* Free all connectors queued for freeing once SRCU period ends */ +static void fsnotify_connector_destroy_workfn(struct work_struct *work) +{ + struct fsnotify_mark_connector *conn, *free; + + spin_lock(&destroy_lock); + conn = connector_destroy_list; + connector_destroy_list = NULL; + spin_unlock(&destroy_lock); + + synchronize_srcu(&fsnotify_mark_srcu); + while (conn) { + free = conn; + conn = conn->destroy_next; + kmem_cache_free(fsnotify_mark_connector_cachep, free); + } +} + +static void *fsnotify_detach_connector_from_object( + struct fsnotify_mark_connector *conn, + unsigned int *type) +{ + struct inode *inode = NULL; + + *type = conn->type; + if (conn->type == FSNOTIFY_OBJ_TYPE_DETACHED) + return NULL; + + if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) { + inode = fsnotify_conn_inode(conn); + inode->i_fsnotify_mask = 0; + atomic_long_inc(&inode->i_sb->s_fsnotify_inode_refs); + } else if (conn->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) { + fsnotify_conn_mount(conn)->mnt_fsnotify_mask = 0; + } else if (conn->type == FSNOTIFY_OBJ_TYPE_SB) { + fsnotify_conn_sb(conn)->s_fsnotify_mask = 0; + } + + rcu_assign_pointer(*(conn->obj), NULL); + conn->obj = NULL; + conn->type = FSNOTIFY_OBJ_TYPE_DETACHED; + + return inode; +} + +static void fsnotify_final_mark_destroy(struct fsnotify_mark *mark) +{ + struct fsnotify_group *group = mark->group; + + if (WARN_ON_ONCE(!group)) + return; + group->ops->free_mark(mark); + fsnotify_put_group(group); +} + +/* Drop object reference originally held by a connector */ +static void fsnotify_drop_object(unsigned int type, void *objp) +{ + struct inode *inode; + struct super_block *sb; + + if (!objp) + return; + /* Currently only inode references are passed to be dropped */ + if (WARN_ON_ONCE(type != FSNOTIFY_OBJ_TYPE_INODE)) + return; + inode = objp; + sb = inode->i_sb; + iput(inode); + if (atomic_long_dec_and_test(&sb->s_fsnotify_inode_refs)) + wake_up_var(&sb->s_fsnotify_inode_refs); +} + +void fsnotify_put_mark(struct fsnotify_mark *mark) +{ + struct fsnotify_mark_connector *conn = READ_ONCE(mark->connector); + void *objp = NULL; + unsigned int type = FSNOTIFY_OBJ_TYPE_DETACHED; + bool free_conn = false; + + /* Catch marks that were actually never attached to object */ + if (!conn) { + if (refcount_dec_and_test(&mark->refcnt)) + fsnotify_final_mark_destroy(mark); + return; + } + + /* + * We have to be careful so that traversals of obj_list under lock can + * safely grab mark reference. + */ + if (!refcount_dec_and_lock(&mark->refcnt, &conn->lock)) + return; + + hlist_del_init_rcu(&mark->obj_list); + if (hlist_empty(&conn->list)) { + objp = fsnotify_detach_connector_from_object(conn, &type); + free_conn = true; + } else { + __fsnotify_recalc_mask(conn); + } + WRITE_ONCE(mark->connector, NULL); + spin_unlock(&conn->lock); + + fsnotify_drop_object(type, objp); + + if (free_conn) { + spin_lock(&destroy_lock); + conn->destroy_next = connector_destroy_list; + connector_destroy_list = conn; + spin_unlock(&destroy_lock); + queue_work(system_unbound_wq, &connector_reaper_work); + } + /* + * Note that we didn't update flags telling whether inode cares about + * what's happening with children. We update these flags from + * __fsnotify_parent() lazily when next event happens on one of our + * children. + */ + spin_lock(&destroy_lock); + list_add(&mark->g_list, &destroy_list); + spin_unlock(&destroy_lock); + queue_delayed_work(system_unbound_wq, &reaper_work, + FSNOTIFY_REAPER_DELAY); +} +EXPORT_SYMBOL_GPL(fsnotify_put_mark); + +/* + * Get mark reference when we found the mark via lockless traversal of object + * list. Mark can be already removed from the list by now and on its way to be + * destroyed once SRCU period ends. + * + * Also pin the group so it doesn't disappear under us. + */ +static bool fsnotify_get_mark_safe(struct fsnotify_mark *mark) +{ + if (!mark) + return true; + + if (refcount_inc_not_zero(&mark->refcnt)) { + spin_lock(&mark->lock); + if (mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) { + /* mark is attached, group is still alive then */ + atomic_inc(&mark->group->user_waits); + spin_unlock(&mark->lock); + return true; + } + spin_unlock(&mark->lock); + fsnotify_put_mark(mark); + } + return false; +} + +/* + * Puts marks and wakes up group destruction if necessary. + * + * Pairs with fsnotify_get_mark_safe() + */ +static void fsnotify_put_mark_wake(struct fsnotify_mark *mark) +{ + if (mark) { + struct fsnotify_group *group = mark->group; + + fsnotify_put_mark(mark); + /* + * We abuse notification_waitq on group shutdown for waiting for + * all marks pinned when waiting for userspace. + */ + if (atomic_dec_and_test(&group->user_waits) && group->shutdown) + wake_up(&group->notification_waitq); + } +} + +bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info) + __releases(&fsnotify_mark_srcu) +{ + int type; + + fsnotify_foreach_obj_type(type) { + /* This can fail if mark is being removed */ + if (!fsnotify_get_mark_safe(iter_info->marks[type])) { + __release(&fsnotify_mark_srcu); + goto fail; + } + } + + /* + * Now that both marks are pinned by refcount in the inode / vfsmount + * lists, we can drop SRCU lock, and safely resume the list iteration + * once userspace returns. + */ + srcu_read_unlock(&fsnotify_mark_srcu, iter_info->srcu_idx); + + return true; + +fail: + for (type--; type >= 0; type--) + fsnotify_put_mark_wake(iter_info->marks[type]); + return false; +} + +void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info) + __acquires(&fsnotify_mark_srcu) +{ + int type; + + iter_info->srcu_idx = srcu_read_lock(&fsnotify_mark_srcu); + fsnotify_foreach_obj_type(type) + fsnotify_put_mark_wake(iter_info->marks[type]); +} + +/* + * Mark mark as detached, remove it from group list. Mark still stays in object + * list until its last reference is dropped. Note that we rely on mark being + * removed from group list before corresponding reference to it is dropped. In + * particular we rely on mark->connector being valid while we hold + * group->mark_mutex if we found the mark through g_list. + * + * Must be called with group->mark_mutex held. The caller must either hold + * reference to the mark or be protected by fsnotify_mark_srcu. + */ +void fsnotify_detach_mark(struct fsnotify_mark *mark) +{ + struct fsnotify_group *group = mark->group; + + WARN_ON_ONCE(!mutex_is_locked(&group->mark_mutex)); + WARN_ON_ONCE(!srcu_read_lock_held(&fsnotify_mark_srcu) && + refcount_read(&mark->refcnt) < 1 + + !!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)); + + spin_lock(&mark->lock); + /* something else already called this function on this mark */ + if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) { + spin_unlock(&mark->lock); + return; + } + mark->flags &= ~FSNOTIFY_MARK_FLAG_ATTACHED; + list_del_init(&mark->g_list); + spin_unlock(&mark->lock); + + atomic_dec(&group->num_marks); + + /* Drop mark reference acquired in fsnotify_add_mark_locked() */ + fsnotify_put_mark(mark); +} + +/* + * Free fsnotify mark. The mark is actually only marked as being freed. The + * freeing is actually happening only once last reference to the mark is + * dropped from a workqueue which first waits for srcu period end. + * + * Caller must have a reference to the mark or be protected by + * fsnotify_mark_srcu. + */ +void fsnotify_free_mark(struct fsnotify_mark *mark) +{ + struct fsnotify_group *group = mark->group; + + spin_lock(&mark->lock); + /* something else already called this function on this mark */ + if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) { + spin_unlock(&mark->lock); + return; + } + mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE; + spin_unlock(&mark->lock); + + /* + * Some groups like to know that marks are being freed. This is a + * callback to the group function to let it know that this mark + * is being freed. + */ + if (group->ops->freeing_mark) + group->ops->freeing_mark(mark, group); +} + +void fsnotify_destroy_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group) +{ + mutex_lock(&group->mark_mutex); + fsnotify_detach_mark(mark); + mutex_unlock(&group->mark_mutex); + fsnotify_free_mark(mark); +} +EXPORT_SYMBOL_GPL(fsnotify_destroy_mark); + +/* + * Sorting function for lists of fsnotify marks. + * + * Fanotify supports different notification classes (reflected as priority of + * notification group). Events shall be passed to notification groups in + * decreasing priority order. To achieve this marks in notification lists for + * inodes and vfsmounts are sorted so that priorities of corresponding groups + * are descending. + * + * Furthermore correct handling of the ignore mask requires processing inode + * and vfsmount marks of each group together. Using the group address as + * further sort criterion provides a unique sorting order and thus we can + * merge inode and vfsmount lists of marks in linear time and find groups + * present in both lists. + * + * A return value of 1 signifies that b has priority over a. + * A return value of 0 signifies that the two marks have to be handled together. + * A return value of -1 signifies that a has priority over b. + */ +int fsnotify_compare_groups(struct fsnotify_group *a, struct fsnotify_group *b) +{ + if (a == b) + return 0; + if (!a) + return 1; + if (!b) + return -1; + if (a->priority < b->priority) + return 1; + if (a->priority > b->priority) + return -1; + if (a < b) + return 1; + return -1; +} + +static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp, + unsigned int type, + __kernel_fsid_t *fsid) +{ + struct inode *inode = NULL; + struct fsnotify_mark_connector *conn; + + conn = kmem_cache_alloc(fsnotify_mark_connector_cachep, GFP_KERNEL); + if (!conn) + return -ENOMEM; + spin_lock_init(&conn->lock); + INIT_HLIST_HEAD(&conn->list); + conn->type = type; + conn->obj = connp; + /* Cache fsid of filesystem containing the object */ + if (fsid) { + conn->fsid = *fsid; + conn->flags = FSNOTIFY_CONN_FLAG_HAS_FSID; + } else { + conn->fsid.val[0] = conn->fsid.val[1] = 0; + conn->flags = 0; + } + if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) + inode = igrab(fsnotify_conn_inode(conn)); + /* + * cmpxchg() provides the barrier so that readers of *connp can see + * only initialized structure + */ + if (cmpxchg(connp, NULL, conn)) { + /* Someone else created list structure for us */ + if (inode) + iput(inode); + kmem_cache_free(fsnotify_mark_connector_cachep, conn); + } + + return 0; +} + +/* + * Get mark connector, make sure it is alive and return with its lock held. + * This is for users that get connector pointer from inode or mount. Users that + * hold reference to a mark on the list may directly lock connector->lock as + * they are sure list cannot go away under them. + */ +static struct fsnotify_mark_connector *fsnotify_grab_connector( + fsnotify_connp_t *connp) +{ + struct fsnotify_mark_connector *conn; + int idx; + + idx = srcu_read_lock(&fsnotify_mark_srcu); + conn = srcu_dereference(*connp, &fsnotify_mark_srcu); + if (!conn) + goto out; + spin_lock(&conn->lock); + if (conn->type == FSNOTIFY_OBJ_TYPE_DETACHED) { + spin_unlock(&conn->lock); + srcu_read_unlock(&fsnotify_mark_srcu, idx); + return NULL; + } +out: + srcu_read_unlock(&fsnotify_mark_srcu, idx); + return conn; +} + +/* + * Add mark into proper place in given list of marks. These marks may be used + * for the fsnotify backend to determine which event types should be delivered + * to which group and for which inodes. These marks are ordered according to + * priority, highest number first, and then by the group's location in memory. + */ +static int fsnotify_add_mark_list(struct fsnotify_mark *mark, + fsnotify_connp_t *connp, unsigned int type, + int allow_dups, __kernel_fsid_t *fsid) +{ + struct fsnotify_mark *lmark, *last = NULL; + struct fsnotify_mark_connector *conn; + int cmp; + int err = 0; + + if (WARN_ON(!fsnotify_valid_obj_type(type))) + return -EINVAL; + + /* Backend is expected to check for zero fsid (e.g. tmpfs) */ + if (fsid && WARN_ON_ONCE(!fsid->val[0] && !fsid->val[1])) + return -ENODEV; + +restart: + spin_lock(&mark->lock); + conn = fsnotify_grab_connector(connp); + if (!conn) { + spin_unlock(&mark->lock); + err = fsnotify_attach_connector_to_object(connp, type, fsid); + if (err) + return err; + goto restart; + } else if (fsid && !(conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID)) { + conn->fsid = *fsid; + /* Pairs with smp_rmb() in fanotify_get_fsid() */ + smp_wmb(); + conn->flags |= FSNOTIFY_CONN_FLAG_HAS_FSID; + } else if (fsid && (conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID) && + (fsid->val[0] != conn->fsid.val[0] || + fsid->val[1] != conn->fsid.val[1])) { + /* + * Backend is expected to check for non uniform fsid + * (e.g. btrfs), but maybe we missed something? + * Only allow setting conn->fsid once to non zero fsid. + * inotify and non-fid fanotify groups do not set nor test + * conn->fsid. + */ + pr_warn_ratelimited("%s: fsid mismatch on object of type %u: " + "%x.%x != %x.%x\n", __func__, conn->type, + fsid->val[0], fsid->val[1], + conn->fsid.val[0], conn->fsid.val[1]); + err = -EXDEV; + goto out_err; + } + + /* is mark the first mark? */ + if (hlist_empty(&conn->list)) { + hlist_add_head_rcu(&mark->obj_list, &conn->list); + goto added; + } + + /* should mark be in the middle of the current list? */ + hlist_for_each_entry(lmark, &conn->list, obj_list) { + last = lmark; + + if ((lmark->group == mark->group) && + (lmark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) && + !allow_dups) { + err = -EEXIST; + goto out_err; + } + + cmp = fsnotify_compare_groups(lmark->group, mark->group); + if (cmp >= 0) { + hlist_add_before_rcu(&mark->obj_list, &lmark->obj_list); + goto added; + } + } + + BUG_ON(last == NULL); + /* mark should be the last entry. last is the current last entry */ + hlist_add_behind_rcu(&mark->obj_list, &last->obj_list); +added: + /* + * Since connector is attached to object using cmpxchg() we are + * guaranteed that connector initialization is fully visible by anyone + * seeing mark->connector set. + */ + WRITE_ONCE(mark->connector, conn); +out_err: + spin_unlock(&conn->lock); + spin_unlock(&mark->lock); + return err; +} + +/* + * Attach an initialized mark to a given group and fs object. + * These marks may be used for the fsnotify backend to determine which + * event types should be delivered to which group. + */ +int fsnotify_add_mark_locked(struct fsnotify_mark *mark, + fsnotify_connp_t *connp, unsigned int type, + int allow_dups, __kernel_fsid_t *fsid) +{ + struct fsnotify_group *group = mark->group; + int ret = 0; + + BUG_ON(!mutex_is_locked(&group->mark_mutex)); + + /* + * LOCKING ORDER!!!! + * group->mark_mutex + * mark->lock + * mark->connector->lock + */ + spin_lock(&mark->lock); + mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE | FSNOTIFY_MARK_FLAG_ATTACHED; + + list_add(&mark->g_list, &group->marks_list); + atomic_inc(&group->num_marks); + fsnotify_get_mark(mark); /* for g_list */ + spin_unlock(&mark->lock); + + ret = fsnotify_add_mark_list(mark, connp, type, allow_dups, fsid); + if (ret) + goto err; + + if (mark->mask) + fsnotify_recalc_mask(mark->connector); + + return ret; +err: + spin_lock(&mark->lock); + mark->flags &= ~(FSNOTIFY_MARK_FLAG_ALIVE | + FSNOTIFY_MARK_FLAG_ATTACHED); + list_del_init(&mark->g_list); + spin_unlock(&mark->lock); + atomic_dec(&group->num_marks); + + fsnotify_put_mark(mark); + return ret; +} + +int fsnotify_add_mark(struct fsnotify_mark *mark, fsnotify_connp_t *connp, + unsigned int type, int allow_dups, __kernel_fsid_t *fsid) +{ + int ret; + struct fsnotify_group *group = mark->group; + + mutex_lock(&group->mark_mutex); + ret = fsnotify_add_mark_locked(mark, connp, type, allow_dups, fsid); + mutex_unlock(&group->mark_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(fsnotify_add_mark); + +/* + * Given a list of marks, find the mark associated with given group. If found + * take a reference to that mark and return it, else return NULL. + */ +struct fsnotify_mark *fsnotify_find_mark(fsnotify_connp_t *connp, + struct fsnotify_group *group) +{ + struct fsnotify_mark_connector *conn; + struct fsnotify_mark *mark; + + conn = fsnotify_grab_connector(connp); + if (!conn) + return NULL; + + hlist_for_each_entry(mark, &conn->list, obj_list) { + if (mark->group == group && + (mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) { + fsnotify_get_mark(mark); + spin_unlock(&conn->lock); + return mark; + } + } + spin_unlock(&conn->lock); + return NULL; +} +EXPORT_SYMBOL_GPL(fsnotify_find_mark); + +/* Clear any marks in a group with given type mask */ +void fsnotify_clear_marks_by_group(struct fsnotify_group *group, + unsigned int type_mask) +{ + struct fsnotify_mark *lmark, *mark; + LIST_HEAD(to_free); + struct list_head *head = &to_free; + + /* Skip selection step if we want to clear all marks. */ + if (type_mask == FSNOTIFY_OBJ_ALL_TYPES_MASK) { + head = &group->marks_list; + goto clear; + } + /* + * We have to be really careful here. Anytime we drop mark_mutex, e.g. + * fsnotify_clear_marks_by_inode() can come and free marks. Even in our + * to_free list so we have to use mark_mutex even when accessing that + * list. And freeing mark requires us to drop mark_mutex. So we can + * reliably free only the first mark in the list. That's why we first + * move marks to free to to_free list in one go and then free marks in + * to_free list one by one. + */ + mutex_lock(&group->mark_mutex); + list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) { + if ((1U << mark->connector->type) & type_mask) + list_move(&mark->g_list, &to_free); + } + mutex_unlock(&group->mark_mutex); + +clear: + while (1) { + mutex_lock(&group->mark_mutex); + if (list_empty(head)) { + mutex_unlock(&group->mark_mutex); + break; + } + mark = list_first_entry(head, struct fsnotify_mark, g_list); + fsnotify_get_mark(mark); + fsnotify_detach_mark(mark); + mutex_unlock(&group->mark_mutex); + fsnotify_free_mark(mark); + fsnotify_put_mark(mark); + } +} + +/* Destroy all marks attached to an object via connector */ +void fsnotify_destroy_marks(fsnotify_connp_t *connp) +{ + struct fsnotify_mark_connector *conn; + struct fsnotify_mark *mark, *old_mark = NULL; + void *objp; + unsigned int type; + + conn = fsnotify_grab_connector(connp); + if (!conn) + return; + /* + * We have to be careful since we can race with e.g. + * fsnotify_clear_marks_by_group() and once we drop the conn->lock, the + * list can get modified. However we are holding mark reference and + * thus our mark cannot be removed from obj_list so we can continue + * iteration after regaining conn->lock. + */ + hlist_for_each_entry(mark, &conn->list, obj_list) { + fsnotify_get_mark(mark); + spin_unlock(&conn->lock); + if (old_mark) + fsnotify_put_mark(old_mark); + old_mark = mark; + fsnotify_destroy_mark(mark, mark->group); + spin_lock(&conn->lock); + } + /* + * Detach list from object now so that we don't pin inode until all + * mark references get dropped. It would lead to strange results such + * as delaying inode deletion or blocking unmount. + */ + objp = fsnotify_detach_connector_from_object(conn, &type); + spin_unlock(&conn->lock); + if (old_mark) + fsnotify_put_mark(old_mark); + fsnotify_drop_object(type, objp); +} + +/* + * Nothing fancy, just initialize lists and locks and counters. + */ +void fsnotify_init_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group) +{ + memset(mark, 0, sizeof(*mark)); + spin_lock_init(&mark->lock); + refcount_set(&mark->refcnt, 1); + fsnotify_get_group(group); + mark->group = group; + WRITE_ONCE(mark->connector, NULL); +} +EXPORT_SYMBOL_GPL(fsnotify_init_mark); + +/* + * Destroy all marks in destroy_list, waits for SRCU period to finish before + * actually freeing marks. + */ +static void fsnotify_mark_destroy_workfn(struct work_struct *work) +{ + struct fsnotify_mark *mark, *next; + struct list_head private_destroy_list; + + spin_lock(&destroy_lock); + /* exchange the list head */ + list_replace_init(&destroy_list, &private_destroy_list); + spin_unlock(&destroy_lock); + + synchronize_srcu(&fsnotify_mark_srcu); + + list_for_each_entry_safe(mark, next, &private_destroy_list, g_list) { + list_del_init(&mark->g_list); + fsnotify_final_mark_destroy(mark); + } +} + +/* Wait for all marks queued for destruction to be actually destroyed */ +void fsnotify_wait_marks_destroyed(void) +{ + flush_delayed_work(&reaper_work); +} +EXPORT_SYMBOL_GPL(fsnotify_wait_marks_destroyed); diff --git a/fs/notify/notification.c b/fs/notify/notification.c new file mode 100644 index 000000000..75d79d6d3 --- /dev/null +++ b/fs/notify/notification.c @@ -0,0 +1,189 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + */ + +/* + * Basic idea behind the notification queue: An fsnotify group (like inotify) + * sends the userspace notification about events asynchronously some time after + * the event happened. When inotify gets an event it will need to add that + * event to the group notify queue. Since a single event might need to be on + * multiple group's notification queues we can't add the event directly to each + * queue and instead add a small "event_holder" to each queue. This event_holder + * has a pointer back to the original event. Since the majority of events are + * going to end up on one, and only one, notification queue we embed one + * event_holder into each event. This means we have a single allocation instead + * of always needing two. If the embedded event_holder is already in use by + * another group a new event_holder (from fsnotify_event_holder_cachep) will be + * allocated and used. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mount.h> +#include <linux/mutex.h> +#include <linux/namei.h> +#include <linux/path.h> +#include <linux/slab.h> +#include <linux/spinlock.h> + +#include <linux/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +static atomic_t fsnotify_sync_cookie = ATOMIC_INIT(0); + +/** + * fsnotify_get_cookie - return a unique cookie for use in synchronizing events. + * Called from fsnotify_move, which is inlined into filesystem modules. + */ +u32 fsnotify_get_cookie(void) +{ + return atomic_inc_return(&fsnotify_sync_cookie); +} +EXPORT_SYMBOL_GPL(fsnotify_get_cookie); + +/* return true if the notify queue is empty, false otherwise */ +bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group) +{ + assert_spin_locked(&group->notification_lock); + return list_empty(&group->notification_list) ? true : false; +} + +void fsnotify_destroy_event(struct fsnotify_group *group, + struct fsnotify_event *event) +{ + /* Overflow events are per-group and we don't want to free them */ + if (!event || event == group->overflow_event) + return; + /* + * If the event is still queued, we have a problem... Do an unreliable + * lockless check first to avoid locking in the common case. The + * locking may be necessary for permission events which got removed + * from the list by a different CPU than the one freeing the event. + */ + if (!list_empty(&event->list)) { + spin_lock(&group->notification_lock); + WARN_ON(!list_empty(&event->list)); + spin_unlock(&group->notification_lock); + } + group->ops->free_event(event); +} + +/* + * Add an event to the group notification queue. The group can later pull this + * event off the queue to deal with. The function returns 0 if the event was + * added to the queue, 1 if the event was merged with some other queued event, + * 2 if the event was not queued - either the queue of events has overflown + * or the group is shutting down. + */ +int fsnotify_add_event(struct fsnotify_group *group, + struct fsnotify_event *event, + int (*merge)(struct list_head *, + struct fsnotify_event *)) +{ + int ret = 0; + struct list_head *list = &group->notification_list; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + spin_lock(&group->notification_lock); + + if (group->shutdown) { + spin_unlock(&group->notification_lock); + return 2; + } + + if (event == group->overflow_event || + group->q_len >= group->max_events) { + ret = 2; + /* Queue overflow event only if it isn't already queued */ + if (!list_empty(&group->overflow_event->list)) { + spin_unlock(&group->notification_lock); + return ret; + } + event = group->overflow_event; + goto queue; + } + + if (!list_empty(list) && merge) { + ret = merge(list, event); + if (ret) { + spin_unlock(&group->notification_lock); + return ret; + } + } + +queue: + group->q_len++; + list_add_tail(&event->list, list); + spin_unlock(&group->notification_lock); + + wake_up(&group->notification_waitq); + kill_fasync(&group->fsn_fa, SIGIO, POLL_IN); + return ret; +} + +void fsnotify_remove_queued_event(struct fsnotify_group *group, + struct fsnotify_event *event) +{ + assert_spin_locked(&group->notification_lock); + /* + * We need to init list head for the case of overflow event so that + * check in fsnotify_add_event() works + */ + list_del_init(&event->list); + group->q_len--; +} + +/* + * Remove and return the first event from the notification list. It is the + * responsibility of the caller to destroy the obtained event + */ +struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group) +{ + struct fsnotify_event *event; + + assert_spin_locked(&group->notification_lock); + + pr_debug("%s: group=%p\n", __func__, group); + + event = list_first_entry(&group->notification_list, + struct fsnotify_event, list); + fsnotify_remove_queued_event(group, event); + return event; +} + +/* + * This will not remove the event, that must be done with + * fsnotify_remove_first_event() + */ +struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group) +{ + assert_spin_locked(&group->notification_lock); + + return list_first_entry(&group->notification_list, + struct fsnotify_event, list); +} + +/* + * Called when a group is being torn down to clean up any outstanding + * event notifications. + */ +void fsnotify_flush_notify(struct fsnotify_group *group) +{ + struct fsnotify_event *event; + + spin_lock(&group->notification_lock); + while (!fsnotify_notify_queue_is_empty(group)) { + event = fsnotify_remove_first_event(group); + spin_unlock(&group->notification_lock); + fsnotify_destroy_event(group, event); + spin_lock(&group->notification_lock); + } + spin_unlock(&group->notification_lock); +} |