diff options
Diffstat (limited to 'fs/notify/fanotify/fanotify.c')
| -rw-r--r-- | fs/notify/fanotify/fanotify.c | 1076 |
1 files changed, 1076 insertions, 0 deletions
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, +}; |