diff options
Diffstat (limited to 'fs/notify/fanotify')
| -rw-r--r-- | fs/notify/fanotify/Kconfig | 27 | ||||
| -rw-r--r-- | fs/notify/fanotify/Makefile | 2 | ||||
| -rw-r--r-- | fs/notify/fanotify/fanotify.c | 1076 | ||||
| -rw-r--r-- | fs/notify/fanotify/fanotify.h | 500 | ||||
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 1900 |
5 files changed, 3505 insertions, 0 deletions
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..a2a15bc4d --- /dev/null +++ b/fs/notify/fanotify/fanotify.c @@ -0,0 +1,1076 @@ +// 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 <linux/stringhash.h> + +#include "fanotify.h" + +static bool fanotify_path_equal(const struct path *p1, const struct path *p2) +{ + return p1->mnt == p2->mnt && p1->dentry == p2->dentry; +} + +static unsigned int fanotify_hash_path(const struct path *path) +{ + return hash_ptr(path->dentry, FANOTIFY_EVENT_HASH_BITS) ^ + hash_ptr(path->mnt, FANOTIFY_EVENT_HASH_BITS); +} + +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 unsigned int fanotify_hash_fsid(__kernel_fsid_t *fsid) +{ + return hash_32(fsid->val[0], FANOTIFY_EVENT_HASH_BITS) ^ + hash_32(fsid->val[1], FANOTIFY_EVENT_HASH_BITS); +} + +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 unsigned int fanotify_hash_fh(struct fanotify_fh *fh) +{ + long salt = (long)fh->type | (long)fh->len << 8; + + /* + * full_name_hash() works long by long, so it handles fh buf optimally. + */ + return full_name_hash((void *)salt, fanotify_fh_buf(fh), fh->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->dir2_fh_totlen != info2->dir2_fh_totlen || + info1->file_fh_totlen != info2->file_fh_totlen || + info1->name_len != info2->name_len || + info1->name2_len != info2->name2_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->dir2_fh_totlen && + !fanotify_fh_equal(fanotify_info_dir2_fh(info1), + fanotify_info_dir2_fh(info2))) + return false; + + if (info1->file_fh_totlen && + !fanotify_fh_equal(fanotify_info_file_fh(info1), + fanotify_info_file_fh(info2))) + return false; + + if (info1->name_len && + memcmp(fanotify_info_name(info1), fanotify_info_name(info2), + info1->name_len)) + return false; + + return !info1->name2_len || + !memcmp(fanotify_info_name2(info1), fanotify_info_name2(info2), + info1->name2_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_error_event_equal(struct fanotify_error_event *fee1, + struct fanotify_error_event *fee2) +{ + /* Error events against the same file system are always merged. */ + if (!fanotify_fsid_equal(&fee1->fsid, &fee2->fsid)) + return false; + + return true; +} + +static bool fanotify_should_merge(struct fanotify_event *old, + struct fanotify_event *new) +{ + pr_debug("%s: old=%p new=%p\n", __func__, old, new); + + if (old->hash != new->hash || + 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; + + /* + * FAN_RENAME event is reported with special info record types, + * so we cannot merge it with other events. + */ + if ((old->mask & FAN_RENAME) != (new->mask & FAN_RENAME)) + 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)); + case FANOTIFY_EVENT_TYPE_FS_ERROR: + return fanotify_error_event_equal(FANOTIFY_EE(old), + FANOTIFY_EE(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 fsnotify_group *group, + struct fsnotify_event *event) +{ + struct fanotify_event *old, *new = FANOTIFY_E(event); + unsigned int bucket = fanotify_event_hash_bucket(group, new); + struct hlist_head *hlist = &group->fanotify_data.merge_hash[bucket]; + int i = 0; + + pr_debug("%s: group=%p event=%p bucket=%u\n", __func__, + group, event, bucket); + + /* + * 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; + + hlist_for_each_entry(old, hlist, merge_list) { + if (++i > FANOTIFY_MAX_MERGE_EVENTS) + break; + if (fanotify_should_merge(old, new)) { + old->mask |= new->mask; + + if (fanotify_is_error_event(old->mask)) + FANOTIFY_EE(old)->err_count++; + + 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); + /* Permission events are not supposed to be hashed */ + WARN_ON_ONCE(!hlist_unhashed(&event->fae.merge_list)); + } + /* + * 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 *match_mask, u32 event_mask, + const void *data, int data_type, + struct inode *dir) +{ + __u32 marks_mask = 0, marks_ignore_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; + bool ondir = event_mask & FAN_ONDIR; + 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 && !ondir) + return 0; + } + + fsnotify_foreach_iter_mark_type(iter_info, mark, type) { + /* + * Apply ignore mask depending on event flags in ignore mask. + */ + marks_ignore_mask |= + fsnotify_effective_ignore_mask(mark, ondir, type); + + /* + * Send the event depending on event flags in mark mask. + */ + if (!fsnotify_mask_applicable(mark->mask, ondir, type)) + continue; + + marks_mask |= mark->mask; + + /* Record the mark types of this group that matched the event */ + *match_mask |= 1U << type; + } + + test_mask = event_mask & marks_mask & ~marks_ignore_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; + int fh_len; + + if (!inode) + return 0; + + exportfs_encode_inode_fh(inode, NULL, &dwords, NULL); + fh_len = dwords << 2; + + /* + * struct fanotify_error_event might be preallocated and is + * limited to MAX_HANDLE_SZ. This should never happen, but + * safeguard by forcing an invalid file handle. + */ + if (WARN_ON_ONCE(fh_len > MAX_HANDLE_SZ)) + return 0; + + return fh_len; +} + +/* + * 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, unsigned int *hash, + 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; + + /* + * Invalid FHs are used by FAN_FS_ERROR for errors not + * linked to any inode. The f_handle won't be reported + * back to userspace. + */ + if (!inode) + goto out; + + /* + * !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) || fh_len > MAX_HANDLE_SZ) + 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; + +out: + /* + * Mix fh into event merge key. Hash might be NULL in case of + * unhashed FID events (i.e. FAN_FS_ERROR). + */ + if (hash) + *hash ^= fanotify_hash_fh(fh); + + 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; +} + +/* + * FAN_REPORT_FID is ambiguous in that it reports the fid of the child for + * some events and the fid of the parent for create/delete/move events. + * + * With the FAN_REPORT_TARGET_FID flag, the fid of the child is reported + * also in create/delete/move events in addition to the fid of the parent + * and the name of the child. + */ +static inline bool fanotify_report_child_fid(unsigned int fid_mode, u32 mask) +{ + if (mask & ALL_FSNOTIFY_DIRENT_EVENTS) + return (fid_mode & FAN_REPORT_TARGET_FID); + + return (fid_mode & FAN_REPORT_FID) && !(mask & FAN_ONDIR); +} + +/* + * The inode to use as identifier when reporting fid depends on the event + * and the group flags. + * + * With the group flag FAN_REPORT_TARGET_FID, always report the child fid. + * + * Without the group flag FAN_REPORT_TARGET_FID, report the modified directory + * fid on dirent events and the child fid otherwise. + * + * For example: + * FS_ATTRIB reports the child fid even if reported on a watched parent. + * FS_CREATE reports the modified dir fid without FAN_REPORT_TARGET_FID. + * and reports the created child fid with FAN_REPORT_TARGET_FID. + */ +static struct inode *fanotify_fid_inode(u32 event_mask, const void *data, + int data_type, struct inode *dir, + unsigned int fid_mode) +{ + if ((event_mask & ALL_FSNOTIFY_DIRENT_EVENTS) && + !(fid_mode & FAN_REPORT_TARGET_FID)) + 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 (inode && S_ISDIR(inode->i_mode)) + return inode; + + return dir; +} + +static struct fanotify_event *fanotify_alloc_path_event(const struct path *path, + unsigned int *hash, + 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; + *hash ^= fanotify_hash_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, + unsigned int *hash, + 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; + *hash ^= fanotify_hash_fsid(fsid); + fanotify_encode_fh(&ffe->object_fh, id, fanotify_encode_fh_len(id), + hash, gfp); + + return &ffe->fae; +} + +static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir, + __kernel_fsid_t *fsid, + const struct qstr *name, + struct inode *child, + struct dentry *moved, + unsigned int *hash, + gfp_t gfp) +{ + struct fanotify_name_event *fne; + struct fanotify_info *info; + struct fanotify_fh *dfh, *ffh; + struct inode *dir2 = moved ? d_inode(moved->d_parent) : NULL; + const struct qstr *name2 = moved ? &moved->d_name : NULL; + unsigned int dir_fh_len = fanotify_encode_fh_len(dir); + unsigned int dir2_fh_len = fanotify_encode_fh_len(dir2); + unsigned int child_fh_len = fanotify_encode_fh_len(child); + unsigned long name_len = name ? name->len : 0; + unsigned long name2_len = name2 ? name2->len : 0; + unsigned int len, size; + + /* Reserve terminating null byte even for empty name */ + size = sizeof(*fne) + name_len + name2_len + 2; + if (dir_fh_len) + size += FANOTIFY_FH_HDR_LEN + dir_fh_len; + if (dir2_fh_len) + size += FANOTIFY_FH_HDR_LEN + dir2_fh_len; + if (child_fh_len) + size += FANOTIFY_FH_HDR_LEN + child_fh_len; + fne = kmalloc(size, gfp); + if (!fne) + return NULL; + + fne->fae.type = FANOTIFY_EVENT_TYPE_FID_NAME; + fne->fsid = *fsid; + *hash ^= fanotify_hash_fsid(fsid); + info = &fne->info; + fanotify_info_init(info); + if (dir_fh_len) { + dfh = fanotify_info_dir_fh(info); + len = fanotify_encode_fh(dfh, dir, dir_fh_len, hash, 0); + fanotify_info_set_dir_fh(info, len); + } + if (dir2_fh_len) { + dfh = fanotify_info_dir2_fh(info); + len = fanotify_encode_fh(dfh, dir2, dir2_fh_len, hash, 0); + fanotify_info_set_dir2_fh(info, len); + } + if (child_fh_len) { + ffh = fanotify_info_file_fh(info); + len = fanotify_encode_fh(ffh, child, child_fh_len, hash, 0); + fanotify_info_set_file_fh(info, len); + } + if (name_len) { + fanotify_info_copy_name(info, name); + *hash ^= full_name_hash((void *)name_len, name->name, name_len); + } + if (name2_len) { + fanotify_info_copy_name2(info, name2); + *hash ^= full_name_hash((void *)name2_len, name2->name, + name2_len); + } + + pr_debug("%s: size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n", + __func__, size, dir_fh_len, child_fh_len, + info->name_len, info->name_len, fanotify_info_name(info)); + + if (dir2_fh_len) { + pr_debug("%s: dir2_fh_len=%u name2_len=%u name2='%.*s'\n", + __func__, dir2_fh_len, info->name2_len, + info->name2_len, fanotify_info_name2(info)); + } + + return &fne->fae; +} + +static struct fanotify_event *fanotify_alloc_error_event( + struct fsnotify_group *group, + __kernel_fsid_t *fsid, + const void *data, int data_type, + unsigned int *hash) +{ + struct fs_error_report *report = + fsnotify_data_error_report(data, data_type); + struct inode *inode; + struct fanotify_error_event *fee; + int fh_len; + + if (WARN_ON_ONCE(!report)) + return NULL; + + fee = mempool_alloc(&group->fanotify_data.error_events_pool, GFP_NOFS); + if (!fee) + return NULL; + + fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR; + fee->error = report->error; + fee->err_count = 1; + fee->fsid = *fsid; + + inode = report->inode; + fh_len = fanotify_encode_fh_len(inode); + + /* Bad fh_len. Fallback to using an invalid fh. Should never happen. */ + if (!fh_len && inode) + inode = NULL; + + fanotify_encode_fh(&fee->object_fh, inode, fh_len, NULL, 0); + + *hash ^= fanotify_hash_fsid(fsid); + + return &fee->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, u32 match_mask) +{ + struct fanotify_event *event = NULL; + gfp_t gfp = GFP_KERNEL_ACCOUNT; + unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + struct inode *id = fanotify_fid_inode(mask, data, data_type, dir, + fid_mode); + struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir); + const struct path *path = fsnotify_data_path(data, data_type); + struct mem_cgroup *old_memcg; + struct dentry *moved = NULL; + struct inode *child = NULL; + bool name_event = false; + unsigned int hash = 0; + bool ondir = mask & FAN_ONDIR; + struct pid *pid; + + if ((fid_mode & FAN_REPORT_DIR_FID) && dirid) { + /* + * For certain events and group flags, report the child fid + * in addition to reporting the parent fid and maybe child name. + */ + if (fanotify_report_child_fid(fid_mode, mask) && id != dirid) + 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) || !ondir) { + name_event = true; + } + + /* + * In the special case of FAN_RENAME event, use the match_mask + * to determine if we need to report only the old parent+name, + * only the new parent+name or both. + * 'dirid' and 'file_name' are the old parent+name and + * 'moved' has the new parent+name. + */ + if (mask & FAN_RENAME) { + bool report_old, report_new; + + if (WARN_ON_ONCE(!match_mask)) + return NULL; + + /* Report both old and new parent+name if sb watching */ + report_old = report_new = + match_mask & (1U << FSNOTIFY_ITER_TYPE_SB); + report_old |= + match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE); + report_new |= + match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE2); + + if (!report_old) { + /* Do not report old parent+name */ + dirid = NULL; + file_name = NULL; + } + if (report_new) { + /* Report new parent+name */ + moved = fsnotify_data_dentry(data, data_type); + } + } + } + + /* + * 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 (fanotify_is_error_event(mask)) { + event = fanotify_alloc_error_event(group, fsid, data, + data_type, &hash); + } else if (name_event && (file_name || moved || child)) { + event = fanotify_alloc_name_event(dirid, fsid, file_name, child, + moved, &hash, gfp); + } else if (fid_mode) { + event = fanotify_alloc_fid_event(id, fsid, &hash, gfp); + } else { + event = fanotify_alloc_path_event(path, &hash, gfp); + } + + if (!event) + goto out; + + if (FAN_GROUP_FLAG(group, FAN_REPORT_TID)) + pid = get_pid(task_pid(current)); + else + pid = get_pid(task_tgid(current)); + + /* Mix event info, FAN_ONDIR flag and pid into event merge key */ + hash ^= hash_long((unsigned long)pid | ondir, FANOTIFY_EVENT_HASH_BITS); + fanotify_init_event(event, hash, mask); + event->pid = pid; + +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) +{ + struct fsnotify_mark *mark; + int type; + __kernel_fsid_t fsid = {}; + + fsnotify_foreach_iter_mark_type(iter_info, mark, type) { + struct fsnotify_mark_connector *conn; + + conn = READ_ONCE(mark->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; +} + +/* + * Add an event to hash table for faster merge. + */ +static void fanotify_insert_event(struct fsnotify_group *group, + struct fsnotify_event *fsn_event) +{ + struct fanotify_event *event = FANOTIFY_E(fsn_event); + unsigned int bucket = fanotify_event_hash_bucket(group, event); + struct hlist_head *hlist = &group->fanotify_data.merge_hash[bucket]; + + assert_spin_locked(&group->notification_lock); + + if (!fanotify_is_hashed_event(event->mask)) + return; + + pr_debug("%s: group=%p event=%p bucket=%u\n", __func__, + group, event, bucket); + + hlist_add_head(&event->merge_list, hlist); +} + +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 = {}; + u32 match_mask = 0; + + 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(FAN_FS_ERROR != FS_ERROR); + BUILD_BUG_ON(FAN_RENAME != FS_RENAME); + + BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 21); + + mask = fanotify_group_event_mask(group, iter_info, &match_mask, + mask, data, data_type, dir); + if (!mask) + return 0; + + pr_debug("%s: group=%p mask=%x report_mask=%x\n", __func__, + group, mask, match_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, match_mask); + 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_insert_event(group, fsn_event, fanotify_merge, + fanotify_insert_event); + 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) +{ + kfree(group->fanotify_data.merge_hash); + if (group->fanotify_data.ucounts) + dec_ucount(group->fanotify_data.ucounts, + UCOUNT_FANOTIFY_GROUPS); + + if (mempool_initialized(&group->fanotify_data.error_events_pool)) + mempool_exit(&group->fanotify_data.error_events_pool); +} + +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_error_event(struct fsnotify_group *group, + struct fanotify_event *event) +{ + struct fanotify_error_event *fee = FANOTIFY_EE(event); + + mempool_free(fee, &group->fanotify_data.error_events_pool); +} + +static void fanotify_free_event(struct fsnotify_group *group, + 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; + case FANOTIFY_EVENT_TYPE_FS_ERROR: + fanotify_free_error_event(group, event); + break; + default: + WARN_ON_ONCE(1); + } +} + +static void fanotify_freeing_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group) +{ + if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS)) + dec_ucount(group->fanotify_data.ucounts, UCOUNT_FANOTIFY_MARKS); +} + +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, + .freeing_mark = fanotify_freeing_mark, + .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..57f51a9a3 --- /dev/null +++ b/fs/notify/fanotify/fanotify.h @@ -0,0 +1,500 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/fsnotify_backend.h> +#include <linux/path.h> +#include <linux/slab.h> +#include <linux/exportfs.h> +#include <linux/hashtable.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 dir2_fh_totlen; + u8 file_fh_totlen; + u8 name_len; + u8 name2_len; + u8 pad[3]; + unsigned char buf[]; + /* + * (struct fanotify_fh) dir_fh starts at buf[0] + * (optional) dir2_fh starts at buf[dir_fh_totlen] + * (optional) file_fh starts at buf[dir_fh_totlen + dir2_fh_totlen] + * name starts at buf[dir_fh_totlen + dir2_fh_totlen + file_fh_totlen] + * ... + */ +#define FANOTIFY_DIR_FH_SIZE(info) ((info)->dir_fh_totlen) +#define FANOTIFY_DIR2_FH_SIZE(info) ((info)->dir2_fh_totlen) +#define FANOTIFY_FILE_FH_SIZE(info) ((info)->file_fh_totlen) +#define FANOTIFY_NAME_SIZE(info) ((info)->name_len + 1) +#define FANOTIFY_NAME2_SIZE(info) ((info)->name2_len + 1) + +#define FANOTIFY_DIR_FH_OFFSET(info) 0 +#define FANOTIFY_DIR2_FH_OFFSET(info) \ + (FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info)) +#define FANOTIFY_FILE_FH_OFFSET(info) \ + (FANOTIFY_DIR2_FH_OFFSET(info) + FANOTIFY_DIR2_FH_SIZE(info)) +#define FANOTIFY_NAME_OFFSET(info) \ + (FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info)) +#define FANOTIFY_NAME2_OFFSET(info) \ + (FANOTIFY_NAME_OFFSET(info) + FANOTIFY_NAME_SIZE(info)) + +#define FANOTIFY_DIR_FH_BUF(info) \ + ((info)->buf + FANOTIFY_DIR_FH_OFFSET(info)) +#define FANOTIFY_DIR2_FH_BUF(info) \ + ((info)->buf + FANOTIFY_DIR2_FH_OFFSET(info)) +#define FANOTIFY_FILE_FH_BUF(info) \ + ((info)->buf + FANOTIFY_FILE_FH_OFFSET(info)) +#define FANOTIFY_NAME_BUF(info) \ + ((info)->buf + FANOTIFY_NAME_OFFSET(info)) +#define FANOTIFY_NAME2_BUF(info) \ + ((info)->buf + FANOTIFY_NAME2_OFFSET(info)) +} __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 *)FANOTIFY_DIR_FH_BUF(info); +} + +static inline int fanotify_info_dir2_fh_len(struct fanotify_info *info) +{ + if (!info->dir2_fh_totlen || + WARN_ON_ONCE(info->dir2_fh_totlen < FANOTIFY_FH_HDR_LEN)) + return 0; + + return info->dir2_fh_totlen - FANOTIFY_FH_HDR_LEN; +} + +static inline struct fanotify_fh *fanotify_info_dir2_fh(struct fanotify_info *info) +{ + return (struct fanotify_fh *)FANOTIFY_DIR2_FH_BUF(info); +} + +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 *)FANOTIFY_FILE_FH_BUF(info); +} + +static inline char *fanotify_info_name(struct fanotify_info *info) +{ + if (!info->name_len) + return NULL; + + return FANOTIFY_NAME_BUF(info); +} + +static inline char *fanotify_info_name2(struct fanotify_info *info) +{ + if (!info->name2_len) + return NULL; + + return FANOTIFY_NAME2_BUF(info); +} + +static inline void fanotify_info_init(struct fanotify_info *info) +{ + BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN + MAX_HANDLE_SZ > U8_MAX); + BUILD_BUG_ON(NAME_MAX > U8_MAX); + + info->dir_fh_totlen = 0; + info->dir2_fh_totlen = 0; + info->file_fh_totlen = 0; + info->name_len = 0; + info->name2_len = 0; +} + +/* These set/copy helpers MUST be called by order */ +static inline void fanotify_info_set_dir_fh(struct fanotify_info *info, + unsigned int totlen) +{ + if (WARN_ON_ONCE(info->dir2_fh_totlen > 0) || + WARN_ON_ONCE(info->file_fh_totlen > 0) || + WARN_ON_ONCE(info->name_len > 0) || + WARN_ON_ONCE(info->name2_len > 0)) + return; + + info->dir_fh_totlen = totlen; +} + +static inline void fanotify_info_set_dir2_fh(struct fanotify_info *info, + unsigned int totlen) +{ + if (WARN_ON_ONCE(info->file_fh_totlen > 0) || + WARN_ON_ONCE(info->name_len > 0) || + WARN_ON_ONCE(info->name2_len > 0)) + return; + + info->dir2_fh_totlen = totlen; +} + +static inline void fanotify_info_set_file_fh(struct fanotify_info *info, + unsigned int totlen) +{ + if (WARN_ON_ONCE(info->name_len > 0) || + WARN_ON_ONCE(info->name2_len > 0)) + return; + + info->file_fh_totlen = totlen; +} + +static inline void fanotify_info_copy_name(struct fanotify_info *info, + const struct qstr *name) +{ + if (WARN_ON_ONCE(name->len > NAME_MAX) || + WARN_ON_ONCE(info->name2_len > 0)) + return; + + info->name_len = name->len; + strcpy(fanotify_info_name(info), name->name); +} + +static inline void fanotify_info_copy_name2(struct fanotify_info *info, + const struct qstr *name) +{ + if (WARN_ON_ONCE(name->len > NAME_MAX)) + return; + + info->name2_len = name->len; + strcpy(fanotify_info_name2(info), 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 */ + FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */ + __FANOTIFY_EVENT_TYPE_NUM +}; + +#define FANOTIFY_EVENT_TYPE_BITS \ + (ilog2(__FANOTIFY_EVENT_TYPE_NUM - 1) + 1) +#define FANOTIFY_EVENT_HASH_BITS \ + (32 - FANOTIFY_EVENT_TYPE_BITS) + +struct fanotify_event { + struct fsnotify_event fse; + struct hlist_node merge_list; /* List for hashed merge */ + u32 mask; + struct { + unsigned int type : FANOTIFY_EVENT_TYPE_BITS; + unsigned int hash : FANOTIFY_EVENT_HASH_BITS; + }; + struct pid *pid; +}; + +static inline void fanotify_init_event(struct fanotify_event *event, + unsigned int hash, u32 mask) +{ + fsnotify_init_event(&event->fse); + INIT_HLIST_NODE(&event->merge_list); + event->hash = hash; + event->mask = mask; + event->pid = NULL; +} + +#define FANOTIFY_INLINE_FH(name, size) \ +struct { \ + struct fanotify_fh (name); \ + /* Space for object_fh.buf[] - access with fanotify_fh_buf() */ \ + unsigned char _inline_fh_buf[(size)]; \ +} + +struct fanotify_fid_event { + struct fanotify_event fae; + __kernel_fsid_t fsid; + + FANOTIFY_INLINE_FH(object_fh, 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); +} + +struct fanotify_error_event { + struct fanotify_event fae; + s32 error; /* Error reported by the Filesystem. */ + u32 err_count; /* Suppressed errors count */ + + __kernel_fsid_t fsid; /* FSID this error refers to. */ + + FANOTIFY_INLINE_FH(object_fh, MAX_HANDLE_SZ); +}; + +static inline struct fanotify_error_event * +FANOTIFY_EE(struct fanotify_event *event) +{ + return container_of(event, struct fanotify_error_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 if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR) + return &FANOTIFY_EE(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 if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR) + return &FANOTIFY_EE(event)->object_fh; + 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; +} + +static inline int fanotify_event_dir2_fh_len(struct fanotify_event *event) +{ + struct fanotify_info *info = fanotify_event_info(event); + + return info ? fanotify_info_dir2_fh_len(info) : 0; +} + +static inline bool fanotify_event_has_object_fh(struct fanotify_event *event) +{ + /* For error events, even zeroed fh are reported. */ + if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR) + return true; + return fanotify_event_object_fh_len(event) > 0; +} + +static inline bool fanotify_event_has_dir_fh(struct fanotify_event *event) +{ + return fanotify_event_dir_fh_len(event) > 0; +} + +static inline bool fanotify_event_has_dir2_fh(struct fanotify_event *event) +{ + return fanotify_event_dir2_fh_len(event) > 0; +} + +static inline bool fanotify_event_has_any_dir_fh(struct fanotify_event *event) +{ + return fanotify_event_has_dir_fh(event) || + fanotify_event_has_dir2_fh(event); +} + +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_is_error_event(u32 mask) +{ + return mask & FAN_FS_ERROR; +} + +static inline const 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; +} + +/* + * Use 128 size hash table to speed up events merge. + */ +#define FANOTIFY_HTABLE_BITS (7) +#define FANOTIFY_HTABLE_SIZE (1 << FANOTIFY_HTABLE_BITS) +#define FANOTIFY_HTABLE_MASK (FANOTIFY_HTABLE_SIZE - 1) + +/* + * Permission events and overflow event do not get merged - don't hash them. + */ +static inline bool fanotify_is_hashed_event(u32 mask) +{ + return !(fanotify_is_perm_event(mask) || + fsnotify_is_overflow_event(mask)); +} + +static inline unsigned int fanotify_event_hash_bucket( + struct fsnotify_group *group, + struct fanotify_event *event) +{ + return event->hash & FANOTIFY_HTABLE_MASK; +} + +static inline unsigned int fanotify_mark_user_flags(struct fsnotify_mark *mark) +{ + unsigned int mflags = 0; + + if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY) + mflags |= FAN_MARK_IGNORED_SURV_MODIFY; + if (mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF) + mflags |= FAN_MARK_EVICTABLE; + if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS) + mflags |= FAN_MARK_IGNORE; + + return mflags; +} diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c new file mode 100644 index 000000000..9df5db0f1 --- /dev/null +++ b/fs/notify/fanotify/fanotify_user.c @@ -0,0 +1,1900 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/fanotify.h> +#include <linux/fcntl.h> +#include <linux/fdtable.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_OLD_DEFAULT_MAX_MARKS 8192 +#define FANOTIFY_DEFAULT_MAX_GROUPS 128 +#define FANOTIFY_DEFAULT_FEE_POOL_SIZE 32 + +/* + * Legacy fanotify marks limits (8192) is per group and we introduced a tunable + * limit of marks per user, similar to inotify. Effectively, the legacy limit + * of fanotify marks per user is <max marks per group> * <max groups per user>. + * This default limit (1M) also happens to match the increased limit of inotify + * max_user_watches since v5.10. + */ +#define FANOTIFY_DEFAULT_MAX_USER_MARKS \ + (FANOTIFY_OLD_DEFAULT_MAX_MARKS * FANOTIFY_DEFAULT_MAX_GROUPS) + +/* + * Most of the memory cost of adding an inode mark is pinning the marked inode. + * The size of the filesystem inode struct is not uniform across filesystems, + * so double the size of a VFS inode is used as a conservative approximation. + */ +#define INODE_MARK_COST (2 * sizeof(struct inode)) + +/* configurable via /proc/sys/fs/fanotify/ */ +static int fanotify_max_queued_events __read_mostly; + +#ifdef CONFIG_SYSCTL + +#include <linux/sysctl.h> + +static long ft_zero = 0; +static long ft_int_max = INT_MAX; + +static struct ctl_table fanotify_table[] = { + { + .procname = "max_user_groups", + .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS], + .maxlen = sizeof(long), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + .extra1 = &ft_zero, + .extra2 = &ft_int_max, + }, + { + .procname = "max_user_marks", + .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS], + .maxlen = sizeof(long), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + .extra1 = &ft_zero, + .extra2 = &ft_int_max, + }, + { + .procname = "max_queued_events", + .data = &fanotify_max_queued_events, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO + }, + { } +}; + +static void __init fanotify_sysctls_init(void) +{ + register_sysctl("fs/fanotify", fanotify_table); +} +#else +#define fanotify_sysctls_init() do { } while (0) +#endif /* CONFIG_SYSCTL */ + +/* + * 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_FID_INFO_HDR_LEN \ + (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) +#define FANOTIFY_PIDFD_INFO_HDR_LEN \ + sizeof(struct fanotify_event_info_pidfd) +#define FANOTIFY_ERROR_INFO_LEN \ + (sizeof(struct fanotify_event_info_error)) + +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_FID_INFO_HDR_LEN + info_len, + FANOTIFY_EVENT_ALIGN); +} + +/* FAN_RENAME may have one or two dir+name info records */ +static int fanotify_dir_name_info_len(struct fanotify_event *event) +{ + struct fanotify_info *info = fanotify_event_info(event); + int dir_fh_len = fanotify_event_dir_fh_len(event); + int dir2_fh_len = fanotify_event_dir2_fh_len(event); + int info_len = 0; + + if (dir_fh_len) + info_len += fanotify_fid_info_len(dir_fh_len, + info->name_len); + if (dir2_fh_len) + info_len += fanotify_fid_info_len(dir2_fh_len, + info->name2_len); + + return info_len; +} + +static size_t fanotify_event_len(unsigned int info_mode, + struct fanotify_event *event) +{ + size_t event_len = FAN_EVENT_METADATA_LEN; + int fh_len; + int dot_len = 0; + + if (!info_mode) + return event_len; + + if (fanotify_is_error_event(event->mask)) + event_len += FANOTIFY_ERROR_INFO_LEN; + + if (fanotify_event_has_any_dir_fh(event)) { + event_len += fanotify_dir_name_info_len(event); + } else if ((info_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 (info_mode & FAN_REPORT_PIDFD) + event_len += FANOTIFY_PIDFD_INFO_HDR_LEN; + + if (fanotify_event_has_object_fh(event)) { + fh_len = fanotify_event_object_fh_len(event); + event_len += fanotify_fid_info_len(fh_len, dot_len); + } + + return event_len; +} + +/* + * Remove an hashed event from merge hash table. + */ +static void fanotify_unhash_event(struct fsnotify_group *group, + struct fanotify_event *event) +{ + assert_spin_locked(&group->notification_lock); + + pr_debug("%s: group=%p event=%p bucket=%u\n", __func__, + group, event, fanotify_event_hash_bucket(group, event)); + + if (WARN_ON_ONCE(hlist_unhashed(&event->merge_list))) + return; + + hlist_del_init(&event->merge_list); +} + +/* + * 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; + struct fanotify_event *event = NULL; + struct fsnotify_event *fsn_event; + unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); + + pr_debug("%s: group=%p count=%zd\n", __func__, group, count); + + spin_lock(&group->notification_lock); + fsn_event = fsnotify_peek_first_event(group); + if (!fsn_event) + goto out; + + event = FANOTIFY_E(fsn_event); + event_size = fanotify_event_len(info_mode, event); + + if (event_size > count) { + event = ERR_PTR(-EINVAL); + goto out; + } + + /* + * Held the notification_lock the whole time, so this is the + * same event we peeked above. + */ + fsnotify_remove_first_event(group); + if (fanotify_is_perm_event(event->mask)) + FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED; + if (fanotify_is_hashed_event(event->mask)) + fanotify_unhash_event(group, event); +out: + spin_unlock(&group->notification_lock); + return event; +} + +static int create_fd(struct fsnotify_group *group, const 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 size_t copy_error_info_to_user(struct fanotify_event *event, + char __user *buf, int count) +{ + struct fanotify_event_info_error info = { }; + struct fanotify_error_event *fee = FANOTIFY_EE(event); + + info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR; + info.hdr.len = FANOTIFY_ERROR_INFO_LEN; + + if (WARN_ON(count < info.hdr.len)) + return -EFAULT; + + info.error = fee->error; + info.error_count = fee->err_count; + + if (copy_to_user(buf, &info, sizeof(info))) + return -EFAULT; + + return info.hdr.len; +} + +static int copy_fid_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 (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: + case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME: + case FAN_EVENT_INFO_TYPE_NEW_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; + + /* Mangle handle_type for bad file_handle */ + if (!fh_len) + handle.handle_type = FILEID_INVALID; + + 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 int copy_pidfd_info_to_user(int pidfd, + char __user *buf, + size_t count) +{ + struct fanotify_event_info_pidfd info = { }; + size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN; + + if (WARN_ON_ONCE(info_len > count)) + return -EFAULT; + + info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD; + info.hdr.len = info_len; + info.pidfd = pidfd; + + if (copy_to_user(buf, &info, info_len)) + return -EFAULT; + + return info_len; +} + +static int copy_info_records_to_user(struct fanotify_event *event, + struct fanotify_info *info, + unsigned int info_mode, int pidfd, + char __user *buf, size_t count) +{ + int ret, total_bytes = 0, info_type = 0; + unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS; + unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; + + /* + * Event info records order is as follows: + * 1. dir fid + name + * 2. (optional) new dir fid + new name + * 3. (optional) child fid + */ + if (fanotify_event_has_dir_fh(event)) { + info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : + FAN_EVENT_INFO_TYPE_DFID; + + /* FAN_RENAME uses special info types */ + if (event->mask & FAN_RENAME) + info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME; + + ret = copy_fid_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) + return ret; + + buf += ret; + count -= ret; + total_bytes += ret; + } + + /* New dir fid+name may be reported in addition to old dir fid+name */ + if (fanotify_event_has_dir2_fh(event)) { + info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME; + ret = copy_fid_info_to_user(fanotify_event_fsid(event), + fanotify_info_dir2_fh(info), + info_type, + fanotify_info_name2(info), + info->name2_len, buf, count); + if (ret < 0) + return ret; + + buf += ret; + count -= ret; + total_bytes += ret; + } + + if (fanotify_event_has_object_fh(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_fid_info_to_user(fanotify_event_fsid(event), + fanotify_event_object_fh(event), + info_type, dot, dot_len, + buf, count); + if (ret < 0) + return ret; + + buf += ret; + count -= ret; + total_bytes += ret; + } + + if (pidfd_mode) { + ret = copy_pidfd_info_to_user(pidfd, buf, count); + if (ret < 0) + return ret; + + buf += ret; + count -= ret; + total_bytes += ret; + } + + if (fanotify_is_error_event(event->mask)) { + ret = copy_error_info_to_user(event, buf, count); + if (ret < 0) + return ret; + buf += ret; + count -= ret; + total_bytes += ret; + } + + return total_bytes; +} + +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; + const struct path *path = fanotify_event_path(event); + struct fanotify_info *info = fanotify_event_info(event); + unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); + unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; + struct file *f = NULL; + int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + metadata.event_len = fanotify_event_len(info_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); + /* + * For an unprivileged listener, event->pid can be used to identify the + * events generated by the listener process itself, without disclosing + * the pids of other processes. + */ + if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && + task_tgid(current) != event->pid) + metadata.pid = 0; + + /* + * For now, fid mode is required for an unprivileged listener and + * fid mode does not report fd in events. Keep this check anyway + * for safety in case fid mode requirement is relaxed in the future + * to allow unprivileged listener to get events with no fd and no fid. + */ + if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && + path && path->mnt && path->dentry) { + fd = create_fd(group, path, &f); + if (fd < 0) + return fd; + } + metadata.fd = fd; + + if (pidfd_mode) { + /* + * Complain if the FAN_REPORT_PIDFD and FAN_REPORT_TID mutual + * exclusion is ever lifted. At the time of incoporating pidfd + * support within fanotify, the pidfd API only supported the + * creation of pidfds for thread-group leaders. + */ + WARN_ON_ONCE(FAN_GROUP_FLAG(group, FAN_REPORT_TID)); + + /* + * The PIDTYPE_TGID check for an event->pid is performed + * preemptively in an attempt to catch out cases where the event + * listener reads events after the event generating process has + * already terminated. Report FAN_NOPIDFD to the event listener + * in those cases, with all other pidfd creation errors being + * reported as FAN_EPIDFD. + */ + if (metadata.pid == 0 || + !pid_has_task(event->pid, PIDTYPE_TGID)) { + pidfd = FAN_NOPIDFD; + } else { + pidfd = pidfd_create(event->pid, 0); + if (pidfd < 0) + pidfd = FAN_EPIDFD; + } + } + + 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; + + if (info_mode) { + ret = copy_info_records_to_user(event, info, info_mode, pidfd, + buf, count); + if (ret < 0) + goto out_close_fd; + } + + if (f) + fd_install(fd, f); + + return metadata.event_len; + +out_close_fd: + if (fd != FAN_NOFD) { + put_unused_fd(fd); + fput(f); + } + + if (pidfd >= 0) + close_fd(pidfd); + + 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; + struct fsnotify_event *fsn_event; + + /* + * 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 ((fsn_event = fsnotify_remove_first_event(group))) { + struct fanotify_event *event = FANOTIFY_E(fsn_event); + + if (!(event->mask & FANOTIFY_PERM_EVENTS)) { + spin_unlock(&group->notification_lock); + fsnotify_destroy_event(group, fsn_event); + } 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 = path_permission(path, 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, newmask; + + /* umask bits cannot be removed by user */ + mask &= ~umask; + spin_lock(&fsn_mark->lock); + oldmask = fsnotify_calc_mask(fsn_mark); + if (!(flags & FANOTIFY_MARK_IGNORE_BITS)) { + fsn_mark->mask &= ~mask; + } else { + fsn_mark->ignore_mask &= ~mask; + } + newmask = fsnotify_calc_mask(fsn_mark); + /* + * 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->ignore_mask) & ~umask); + spin_unlock(&fsn_mark->lock); + + return oldmask & ~newmask; +} + +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; + + fsnotify_group_lock(group); + fsn_mark = fsnotify_find_mark(connp, group); + if (!fsn_mark) { + fsnotify_group_unlock(group); + 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); + fsnotify_group_unlock(group); + 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 bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark, + unsigned int fan_flags) +{ + bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE); + unsigned int ignore = fan_flags & FANOTIFY_MARK_IGNORE_BITS; + bool recalc = false; + + /* + * When using FAN_MARK_IGNORE for the first time, mark starts using + * independent event flags in ignore mask. After that, trying to + * update the ignore mask with the old FAN_MARK_IGNORED_MASK API + * will result in EEXIST error. + */ + if (ignore == FAN_MARK_IGNORE) + fsn_mark->flags |= FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS; + + /* + * Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to + * the removal of the FS_MODIFY bit in calculated mask if it was set + * because of an ignore mask that is now going to survive FS_MODIFY. + */ + if (ignore && (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) && + !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) { + fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; + if (!(fsn_mark->mask & FS_MODIFY)) + recalc = true; + } + + if (fsn_mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE || + want_iref == !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) + return recalc; + + /* + * NO_IREF may be removed from a mark, but not added. + * When removed, fsnotify_recalc_mask() will take the inode ref. + */ + WARN_ON_ONCE(!want_iref); + fsn_mark->flags &= ~FSNOTIFY_MARK_FLAG_NO_IREF; + + return true; +} + +static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, + __u32 mask, unsigned int fan_flags) +{ + bool recalc; + + spin_lock(&fsn_mark->lock); + if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS)) + fsn_mark->mask |= mask; + else + fsn_mark->ignore_mask |= mask; + + recalc = fsnotify_calc_mask(fsn_mark) & + ~fsnotify_conn_mask(fsn_mark->connector); + + recalc |= fanotify_mark_update_flags(fsn_mark, fan_flags); + spin_unlock(&fsn_mark->lock); + + return recalc; +} + +static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, + fsnotify_connp_t *connp, + unsigned int obj_type, + unsigned int fan_flags, + __kernel_fsid_t *fsid) +{ + struct ucounts *ucounts = group->fanotify_data.ucounts; + struct fsnotify_mark *mark; + int ret; + + /* + * Enforce per user marks limits per user in all containing user ns. + * A group with FAN_UNLIMITED_MARKS does not contribute to mark count + * in the limited groups account. + */ + if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) && + !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS)) + return ERR_PTR(-ENOSPC); + + mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); + if (!mark) { + ret = -ENOMEM; + goto out_dec_ucounts; + } + + fsnotify_init_mark(mark, group); + if (fan_flags & FAN_MARK_EVICTABLE) + mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF; + + ret = fsnotify_add_mark_locked(mark, connp, obj_type, 0, fsid); + if (ret) { + fsnotify_put_mark(mark); + goto out_dec_ucounts; + } + + return mark; + +out_dec_ucounts: + if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS)) + dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS); + return ERR_PTR(ret); +} + +static int fanotify_group_init_error_pool(struct fsnotify_group *group) +{ + if (mempool_initialized(&group->fanotify_data.error_events_pool)) + return 0; + + return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool, + FANOTIFY_DEFAULT_FEE_POOL_SIZE, + sizeof(struct fanotify_error_event)); +} + +static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark, + unsigned int fan_flags) +{ + /* + * Non evictable mark cannot be downgraded to evictable mark. + */ + if (fan_flags & FAN_MARK_EVICTABLE && + !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)) + return -EEXIST; + + /* + * New ignore mask semantics cannot be downgraded to old semantics. + */ + if (fan_flags & FAN_MARK_IGNORED_MASK && + fsn_mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS) + return -EEXIST; + + /* + * An ignore mask that survives modify could never be downgraded to not + * survive modify. With new FAN_MARK_IGNORE semantics we make that rule + * explicit and return an error when trying to update the ignore mask + * without the original FAN_MARK_IGNORED_SURV_MODIFY value. + */ + if (fan_flags & FAN_MARK_IGNORE && + !(fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) && + fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY) + return -EEXIST; + + return 0; +} + +static int fanotify_add_mark(struct fsnotify_group *group, + fsnotify_connp_t *connp, unsigned int obj_type, + __u32 mask, unsigned int fan_flags, + __kernel_fsid_t *fsid) +{ + struct fsnotify_mark *fsn_mark; + bool recalc; + int ret = 0; + + fsnotify_group_lock(group); + fsn_mark = fsnotify_find_mark(connp, group); + if (!fsn_mark) { + fsn_mark = fanotify_add_new_mark(group, connp, obj_type, + fan_flags, fsid); + if (IS_ERR(fsn_mark)) { + fsnotify_group_unlock(group); + return PTR_ERR(fsn_mark); + } + } + + /* + * Check if requested mark flags conflict with an existing mark flags. + */ + ret = fanotify_may_update_existing_mark(fsn_mark, fan_flags); + if (ret) + goto out; + + /* + * Error events are pre-allocated per group, only if strictly + * needed (i.e. FAN_FS_ERROR was requested). + */ + if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS) && + (mask & FAN_FS_ERROR)) { + ret = fanotify_group_init_error_pool(group); + if (ret) + goto out; + } + + recalc = fanotify_mark_add_to_mask(fsn_mark, mask, fan_flags); + if (recalc) + fsnotify_recalc_mask(fsn_mark->connector); + +out: + fsnotify_group_unlock(group); + + fsnotify_put_mark(fsn_mark); + return ret; +} + +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 ignore mask, unless that ignore mask is supposed to survive + * modification changes anyway. + */ + if ((flags & FANOTIFY_MARK_IGNORE_BITS) && + !(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; +} + +static struct hlist_head *fanotify_alloc_merge_hash(void) +{ + struct hlist_head *hash; + + hash = kmalloc(sizeof(struct hlist_head) << FANOTIFY_HTABLE_BITS, + GFP_KERNEL_ACCOUNT); + if (!hash) + return NULL; + + __hash_init(hash, FANOTIFY_HTABLE_SIZE); + + return hash; +} + +/* fanotify syscalls */ +SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) +{ + struct fsnotify_group *group; + int f_flags, fd; + unsigned int fid_mode = flags & FANOTIFY_FID_BITS; + unsigned int class = flags & FANOTIFY_CLASS_BITS; + unsigned int internal_flags = 0; + + pr_debug("%s: flags=%x event_f_flags=%x\n", + __func__, flags, event_f_flags); + + if (!capable(CAP_SYS_ADMIN)) { + /* + * An unprivileged user can setup an fanotify group with + * limited functionality - an unprivileged group is limited to + * notification events with file handles and it cannot use + * unlimited queue/marks. + */ + if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode) + return -EPERM; + + /* + * Setting the internal flag FANOTIFY_UNPRIV on the group + * prevents setting mount/filesystem marks on this group and + * prevents reporting pid and open fd in events. + */ + internal_flags |= FANOTIFY_UNPRIV; + } + +#ifdef CONFIG_AUDITSYSCALL + if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT)) +#else + if (flags & ~FANOTIFY_INIT_FLAGS) +#endif + return -EINVAL; + + /* + * A pidfd can only be returned for a thread-group leader; thus + * FAN_REPORT_PIDFD and FAN_REPORT_TID need to remain mutually + * exclusive. + */ + if ((flags & FAN_REPORT_PIDFD) && (flags & FAN_REPORT_TID)) + 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; + + /* + * FAN_REPORT_TARGET_FID requires FAN_REPORT_NAME and FAN_REPORT_FID + * and is used as an indication to report both dir and child fid on all + * dirent events. + */ + if ((fid_mode & FAN_REPORT_TARGET_FID) && + (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID))) + return -EINVAL; + + 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, + FSNOTIFY_GROUP_USER | FSNOTIFY_GROUP_NOFS); + if (IS_ERR(group)) { + return PTR_ERR(group); + } + + /* Enforce groups limits per user in all containing user ns */ + group->fanotify_data.ucounts = inc_ucount(current_user_ns(), + current_euid(), + UCOUNT_FANOTIFY_GROUPS); + if (!group->fanotify_data.ucounts) { + fd = -EMFILE; + goto out_destroy_group; + } + + group->fanotify_data.flags = flags | internal_flags; + group->memcg = get_mem_cgroup_from_mm(current->mm); + + group->fanotify_data.merge_hash = fanotify_alloc_merge_hash(); + if (!group->fanotify_data.merge_hash) { + fd = -ENOMEM; + goto out_destroy_group; + } + + 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_max_queued_events; + } + + if (flags & FAN_UNLIMITED_MARKS) { + fd = -EPERM; + if (!capable(CAP_SYS_ADMIN)) + goto out_destroy_group; + } + + 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; +} + +static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid) +{ + __kernel_fsid_t root_fsid; + int err; + + /* + * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse). + */ + err = vfs_get_fsid(dentry, fsid); + if (err) + return err; + + if (!fsid->val[0] && !fsid->val[1]) + return -ENODEV; + + /* + * Make sure dentry is not of a filesystem subvolume (e.g. btrfs) + * which uses a different fsid than sb root. + */ + err = vfs_get_fsid(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; + + return 0; +} + +/* Check if filesystem can encode a unique fid */ +static int fanotify_test_fid(struct dentry *dentry) +{ + /* + * 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 (!dentry->d_sb->s_export_op || + !dentry->d_sb->s_export_op->fh_to_dentry) + return -EOPNOTSUPP; + + return 0; +} + +static int fanotify_events_supported(struct fsnotify_group *group, + const struct path *path, __u64 mask, + unsigned int flags) +{ + unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; + /* Strict validation of events in non-dir inode mask with v5.17+ APIs */ + bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) || + (mask & FAN_RENAME) || + (flags & FAN_MARK_IGNORE); + + /* + * 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; + + /* + * We shouldn't have allowed setting dirent events and the directory + * flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode, + * but because we always allowed it, error only when using new APIs. + */ + if (strict_dir_events && mark_type == FAN_MARK_INODE && + !d_is_dir(path->dentry) && (mask & FANOTIFY_DIRONLY_EVENT_BITS)) + return -ENOTDIR; + + 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; + unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS; + unsigned int ignore = flags & FANOTIFY_MARK_IGNORE_BITS; + 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 (upper_32_bits(mask)) + 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 (mark_cmd) { + 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; + + + /* We don't allow FAN_MARK_IGNORE & FAN_MARK_IGNORED_MASK together */ + if (ignore == (FAN_MARK_IGNORE | FAN_MARK_IGNORED_MASK)) + return -EINVAL; + + /* + * Event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) have no effect with + * FAN_MARK_IGNORED_MASK. + */ + if (ignore == FAN_MARK_IGNORED_MASK) { + mask &= ~FANOTIFY_EVENT_FLAGS; + umask = 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; + + /* + * An unprivileged user is not allowed to setup mount nor filesystem + * marks. This also includes setting up such marks by a group that + * was initialized by an unprivileged user. + */ + ret = -EPERM; + if ((!capable(CAP_SYS_ADMIN) || + FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) && + mark_type != FAN_MARK_INODE) + goto fput_and_out; + + /* + * 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; + + if (mask & FAN_FS_ERROR && + mark_type != FAN_MARK_FILESYSTEM) + goto fput_and_out; + + /* + * Evictable is only relevant for inode marks, because only inode object + * can be evicted on memory pressure. + */ + if (flags & FAN_MARK_EVICTABLE && + mark_type != FAN_MARK_INODE) + goto fput_and_out; + + /* + * Events that do not carry enough information to report + * event->fd require a group that supports reporting fid. Those + * 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_FD_EVENTS|FANOTIFY_EVENT_FLAGS) && + (!fid_mode || mark_type == FAN_MARK_MOUNT)) + goto fput_and_out; + + /* + * FAN_RENAME uses special info type records to report the old and + * new parent+name. Reporting only old and new parent id is less + * useful and was not implemented. + */ + if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME)) + goto fput_and_out; + + if (mark_cmd == 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 (mark_cmd == FAN_MARK_ADD) { + ret = fanotify_events_supported(group, &path, mask, flags); + if (ret) + goto path_put_and_out; + } + + if (fid_mode) { + ret = fanotify_test_fsid(path.dentry, &__fsid); + if (ret) + goto path_put_and_out; + + ret = fanotify_test_fid(path.dentry); + 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; + + ret = mnt ? -EINVAL : -EISDIR; + /* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */ + if (mark_cmd == FAN_MARK_ADD && ignore == FAN_MARK_IGNORE && + (mnt || S_ISDIR(inode->i_mode)) && + !(flags & FAN_MARK_IGNORED_SURV_MODIFY)) + goto path_put_and_out; + + /* 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) && !ignore) + mask |= FAN_EVENT_ON_CHILD; + } + + /* create/update an inode mark */ + switch (mark_cmd) { + 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) +{ + struct sysinfo si; + int max_marks; + + si_meminfo(&si); + /* + * Allow up to 1% of addressable memory to be accounted for per user + * marks limited to the range [8192, 1048576]. mount and sb marks are + * a lot cheaper than inode marks, but there is no reason for a user + * to have many of those, so calculate by the cost of inode marks. + */ + max_marks = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) / + INODE_MARK_COST; + max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS, + FANOTIFY_DEFAULT_MAX_USER_MARKS); + + BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS); + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 12); + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11); + + 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); + } + + fanotify_max_queued_events = FANOTIFY_DEFAULT_MAX_EVENTS; + init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] = + FANOTIFY_DEFAULT_MAX_GROUPS; + init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks; + fanotify_sysctls_init(); + + return 0; +} +device_initcall(fanotify_user_setup); |