// SPDX-License-Identifier: GPL-2.0 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "../../mount.h" #include "../fdinfo.h" #include "fanotify.h" #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 #define FANOTIFY_DEFAULT_MAX_MARKS 8192 #define FANOTIFY_DEFAULT_MAX_LISTENERS 128 /* * All flags that may be specified in parameter event_f_flags of fanotify_init. * * Internal and external open flags are stored together in field f_flags of * struct file. Only external open flags shall be allowed in event_f_flags. * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be * excluded. */ #define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \ O_ACCMODE | O_APPEND | O_NONBLOCK | \ __O_SYNC | O_DSYNC | O_CLOEXEC | \ O_LARGEFILE | O_NOATIME ) extern const struct fsnotify_ops fanotify_fsnotify_ops; struct kmem_cache *fanotify_mark_cache __read_mostly; struct kmem_cache *fanotify_fid_event_cachep __read_mostly; struct kmem_cache *fanotify_path_event_cachep __read_mostly; struct kmem_cache *fanotify_perm_event_cachep __read_mostly; #define FANOTIFY_EVENT_ALIGN 4 #define FANOTIFY_INFO_HDR_LEN \ (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) static int fanotify_fid_info_len(int fh_len, int name_len) { int info_len = fh_len; if (name_len) info_len += name_len + 1; return roundup(FANOTIFY_INFO_HDR_LEN + info_len, FANOTIFY_EVENT_ALIGN); } static int fanotify_event_info_len(unsigned int fid_mode, struct fanotify_event *event) { struct fanotify_info *info = fanotify_event_info(event); int dir_fh_len = fanotify_event_dir_fh_len(event); int fh_len = fanotify_event_object_fh_len(event); int info_len = 0; int dot_len = 0; if (dir_fh_len) { info_len += fanotify_fid_info_len(dir_fh_len, info->name_len); } else if ((fid_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) { /* * With group flag FAN_REPORT_NAME, if name was not recorded in * event on a directory, we will report the name ".". */ dot_len = 1; } if (fh_len) info_len += fanotify_fid_info_len(fh_len, dot_len); return info_len; } /* * Get an fanotify notification event if one exists and is small * enough to fit in "count". Return an error pointer if the count * is not large enough. When permission event is dequeued, its state is * updated accordingly. */ static struct fanotify_event *get_one_event(struct fsnotify_group *group, size_t count) { size_t event_size = FAN_EVENT_METADATA_LEN; struct fanotify_event *event = NULL; unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); pr_debug("%s: group=%p count=%zd\n", __func__, group, count); spin_lock(&group->notification_lock); if (fsnotify_notify_queue_is_empty(group)) goto out; if (fid_mode) { event_size += fanotify_event_info_len(fid_mode, FANOTIFY_E(fsnotify_peek_first_event(group))); } if (event_size > count) { event = ERR_PTR(-EINVAL); goto out; } event = FANOTIFY_E(fsnotify_remove_first_event(group)); if (fanotify_is_perm_event(event->mask)) FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED; out: spin_unlock(&group->notification_lock); return event; } static int create_fd(struct fsnotify_group *group, struct path *path, struct file **file) { int client_fd; struct file *new_file; client_fd = get_unused_fd_flags(group->fanotify_data.f_flags); if (client_fd < 0) return client_fd; /* * we need a new file handle for the userspace program so it can read even if it was * originally opened O_WRONLY. */ new_file = dentry_open(path, group->fanotify_data.f_flags | FMODE_NONOTIFY, current_cred()); if (IS_ERR(new_file)) { /* * we still send an event even if we can't open the file. this * can happen when say tasks are gone and we try to open their * /proc files or we try to open a WRONLY file like in sysfs * we just send the errno to userspace since there isn't much * else we can do. */ put_unused_fd(client_fd); client_fd = PTR_ERR(new_file); } else { *file = new_file; } return client_fd; } /* * Finish processing of permission event by setting it to ANSWERED state and * drop group->notification_lock. */ static void finish_permission_event(struct fsnotify_group *group, struct fanotify_perm_event *event, unsigned int response) __releases(&group->notification_lock) { bool destroy = false; assert_spin_locked(&group->notification_lock); event->response = response; if (event->state == FAN_EVENT_CANCELED) destroy = true; else event->state = FAN_EVENT_ANSWERED; spin_unlock(&group->notification_lock); if (destroy) fsnotify_destroy_event(group, &event->fae.fse); } static int process_access_response(struct fsnotify_group *group, struct fanotify_response *response_struct) { struct fanotify_perm_event *event; int fd = response_struct->fd; int response = response_struct->response; pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group, fd, response); /* * make sure the response is valid, if invalid we do nothing and either * userspace can send a valid response or we will clean it up after the * timeout */ switch (response & ~FAN_AUDIT) { case FAN_ALLOW: case FAN_DENY: break; default: return -EINVAL; } if (fd < 0) return -EINVAL; if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT)) return -EINVAL; spin_lock(&group->notification_lock); list_for_each_entry(event, &group->fanotify_data.access_list, fae.fse.list) { if (event->fd != fd) continue; list_del_init(&event->fae.fse.list); finish_permission_event(group, event, response); wake_up(&group->fanotify_data.access_waitq); return 0; } spin_unlock(&group->notification_lock); return -ENOENT; } static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, int info_type, const char *name, size_t name_len, char __user *buf, size_t count) { struct fanotify_event_info_fid info = { }; struct file_handle handle = { }; unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf; size_t fh_len = fh ? fh->len : 0; size_t info_len = fanotify_fid_info_len(fh_len, name_len); size_t len = info_len; pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n", __func__, fh_len, name_len, info_len, count); if (!fh_len) return 0; if (WARN_ON_ONCE(len < sizeof(info) || len > count)) return -EFAULT; /* * Copy event info fid header followed by variable sized file handle * and optionally followed by variable sized filename. */ switch (info_type) { case FAN_EVENT_INFO_TYPE_FID: case FAN_EVENT_INFO_TYPE_DFID: if (WARN_ON_ONCE(name_len)) return -EFAULT; break; case FAN_EVENT_INFO_TYPE_DFID_NAME: if (WARN_ON_ONCE(!name || !name_len)) return -EFAULT; break; default: return -EFAULT; } info.hdr.info_type = info_type; info.hdr.len = len; info.fsid = *fsid; if (copy_to_user(buf, &info, sizeof(info))) return -EFAULT; buf += sizeof(info); len -= sizeof(info); if (WARN_ON_ONCE(len < sizeof(handle))) return -EFAULT; handle.handle_type = fh->type; handle.handle_bytes = fh_len; if (copy_to_user(buf, &handle, sizeof(handle))) return -EFAULT; buf += sizeof(handle); len -= sizeof(handle); if (WARN_ON_ONCE(len < fh_len)) return -EFAULT; /* * For an inline fh and inline file name, copy through stack to exclude * the copy from usercopy hardening protections. */ fh_buf = fanotify_fh_buf(fh); if (fh_len <= FANOTIFY_INLINE_FH_LEN) { memcpy(bounce, fh_buf, fh_len); fh_buf = bounce; } if (copy_to_user(buf, fh_buf, fh_len)) return -EFAULT; buf += fh_len; len -= fh_len; if (name_len) { /* Copy the filename with terminating null */ name_len++; if (WARN_ON_ONCE(len < name_len)) return -EFAULT; if (copy_to_user(buf, name, name_len)) return -EFAULT; buf += name_len; len -= name_len; } /* Pad with 0's */ WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN); if (len > 0 && clear_user(buf, len)) return -EFAULT; return info_len; } static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fanotify_event *event, char __user *buf, size_t count) { struct fanotify_event_metadata metadata; struct path *path = fanotify_event_path(event); struct fanotify_info *info = fanotify_event_info(event); unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); struct file *f = NULL; int ret, fd = FAN_NOFD; int info_type = 0; pr_debug("%s: group=%p event=%p\n", __func__, group, event); metadata.event_len = FAN_EVENT_METADATA_LEN + fanotify_event_info_len(fid_mode, event); metadata.metadata_len = FAN_EVENT_METADATA_LEN; metadata.vers = FANOTIFY_METADATA_VERSION; metadata.reserved = 0; metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS; metadata.pid = pid_vnr(event->pid); if (path && path->mnt && path->dentry) { fd = create_fd(group, path, &f); if (fd < 0) return fd; } metadata.fd = fd; ret = -EFAULT; /* * Sanity check copy size in case get_one_event() and * event_len sizes ever get out of sync. */ if (WARN_ON_ONCE(metadata.event_len > count)) goto out_close_fd; if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN)) goto out_close_fd; buf += FAN_EVENT_METADATA_LEN; count -= FAN_EVENT_METADATA_LEN; if (fanotify_is_perm_event(event->mask)) FANOTIFY_PERM(event)->fd = fd; if (f) fd_install(fd, f); /* Event info records order is: dir fid + name, child fid */ if (fanotify_event_dir_fh_len(event)) { info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : FAN_EVENT_INFO_TYPE_DFID; ret = copy_info_to_user(fanotify_event_fsid(event), fanotify_info_dir_fh(info), info_type, fanotify_info_name(info), info->name_len, buf, count); if (ret < 0) return ret; buf += ret; count -= ret; } if (fanotify_event_object_fh_len(event)) { const char *dot = NULL; int dot_len = 0; if (fid_mode == FAN_REPORT_FID || info_type) { /* * With only group flag FAN_REPORT_FID only type FID is * reported. Second info record type is always FID. */ info_type = FAN_EVENT_INFO_TYPE_FID; } else if ((fid_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) { /* * With group flag FAN_REPORT_NAME, if name was not * recorded in an event on a directory, report the * name "." with info type DFID_NAME. */ info_type = FAN_EVENT_INFO_TYPE_DFID_NAME; dot = "."; dot_len = 1; } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) || (event->mask & FAN_ONDIR)) { /* * With group flag FAN_REPORT_DIR_FID, a single info * record has type DFID for directory entry modification * event and for event on a directory. */ info_type = FAN_EVENT_INFO_TYPE_DFID; } else { /* * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID, * a single info record has type FID for event on a * non-directory, when there is no directory to report. * For example, on FAN_DELETE_SELF event. */ info_type = FAN_EVENT_INFO_TYPE_FID; } ret = copy_info_to_user(fanotify_event_fsid(event), fanotify_event_object_fh(event), info_type, dot, dot_len, buf, count); if (ret < 0) return ret; buf += ret; count -= ret; } return metadata.event_len; out_close_fd: if (fd != FAN_NOFD) { put_unused_fd(fd); fput(f); } return ret; } /* intofiy userspace file descriptor functions */ static __poll_t fanotify_poll(struct file *file, poll_table *wait) { struct fsnotify_group *group = file->private_data; __poll_t ret = 0; poll_wait(file, &group->notification_waitq, wait); spin_lock(&group->notification_lock); if (!fsnotify_notify_queue_is_empty(group)) ret = EPOLLIN | EPOLLRDNORM; spin_unlock(&group->notification_lock); return ret; } static ssize_t fanotify_read(struct file *file, char __user *buf, size_t count, loff_t *pos) { struct fsnotify_group *group; struct fanotify_event *event; char __user *start; int ret; DEFINE_WAIT_FUNC(wait, woken_wake_function); start = buf; group = file->private_data; pr_debug("%s: group=%p\n", __func__, group); add_wait_queue(&group->notification_waitq, &wait); while (1) { /* * User can supply arbitrarily large buffer. Avoid softlockups * in case there are lots of available events. */ cond_resched(); event = get_one_event(group, count); if (IS_ERR(event)) { ret = PTR_ERR(event); break; } if (!event) { ret = -EAGAIN; if (file->f_flags & O_NONBLOCK) break; ret = -ERESTARTSYS; if (signal_pending(current)) break; if (start != buf) break; wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); continue; } ret = copy_event_to_user(group, event, buf, count); if (unlikely(ret == -EOPENSTALE)) { /* * We cannot report events with stale fd so drop it. * Setting ret to 0 will continue the event loop and * do the right thing if there are no more events to * read (i.e. return bytes read, -EAGAIN or wait). */ ret = 0; } /* * Permission events get queued to wait for response. Other * events can be destroyed now. */ if (!fanotify_is_perm_event(event->mask)) { fsnotify_destroy_event(group, &event->fse); } else { if (ret <= 0) { spin_lock(&group->notification_lock); finish_permission_event(group, FANOTIFY_PERM(event), FAN_DENY); wake_up(&group->fanotify_data.access_waitq); } else { spin_lock(&group->notification_lock); list_add_tail(&event->fse.list, &group->fanotify_data.access_list); spin_unlock(&group->notification_lock); } } if (ret < 0) break; buf += ret; count -= ret; } remove_wait_queue(&group->notification_waitq, &wait); if (start != buf && ret != -EFAULT) ret = buf - start; return ret; } static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) { struct fanotify_response response = { .fd = -1, .response = -1 }; struct fsnotify_group *group; int ret; if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) return -EINVAL; group = file->private_data; if (count < sizeof(response)) return -EINVAL; count = sizeof(response); pr_debug("%s: group=%p count=%zu\n", __func__, group, count); if (copy_from_user(&response, buf, count)) return -EFAULT; ret = process_access_response(group, &response); if (ret < 0) count = ret; return count; } static int fanotify_release(struct inode *ignored, struct file *file) { struct fsnotify_group *group = file->private_data; /* * Stop new events from arriving in the notification queue. since * userspace cannot use fanotify fd anymore, no event can enter or * leave access_list by now either. */ fsnotify_group_stop_queueing(group); /* * Process all permission events on access_list and notification queue * and simulate reply from userspace. */ spin_lock(&group->notification_lock); while (!list_empty(&group->fanotify_data.access_list)) { struct fanotify_perm_event *event; event = list_first_entry(&group->fanotify_data.access_list, struct fanotify_perm_event, fae.fse.list); list_del_init(&event->fae.fse.list); finish_permission_event(group, event, FAN_ALLOW); spin_lock(&group->notification_lock); } /* * Destroy all non-permission events. For permission events just * dequeue them and set the response. They will be freed once the * response is consumed and fanotify_get_response() returns. */ while (!fsnotify_notify_queue_is_empty(group)) { struct fanotify_event *event; event = FANOTIFY_E(fsnotify_remove_first_event(group)); if (!(event->mask & FANOTIFY_PERM_EVENTS)) { spin_unlock(&group->notification_lock); fsnotify_destroy_event(group, &event->fse); } else { finish_permission_event(group, FANOTIFY_PERM(event), FAN_ALLOW); } spin_lock(&group->notification_lock); } spin_unlock(&group->notification_lock); /* Response for all permission events it set, wakeup waiters */ wake_up(&group->fanotify_data.access_waitq); /* matches the fanotify_init->fsnotify_alloc_group */ fsnotify_destroy_group(group); return 0; } static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct fsnotify_group *group; struct fsnotify_event *fsn_event; void __user *p; int ret = -ENOTTY; size_t send_len = 0; group = file->private_data; p = (void __user *) arg; switch (cmd) { case FIONREAD: spin_lock(&group->notification_lock); list_for_each_entry(fsn_event, &group->notification_list, list) send_len += FAN_EVENT_METADATA_LEN; spin_unlock(&group->notification_lock); ret = put_user(send_len, (int __user *) p); break; } return ret; } static const struct file_operations fanotify_fops = { .show_fdinfo = fanotify_show_fdinfo, .poll = fanotify_poll, .read = fanotify_read, .write = fanotify_write, .fasync = NULL, .release = fanotify_release, .unlocked_ioctl = fanotify_ioctl, .compat_ioctl = compat_ptr_ioctl, .llseek = noop_llseek, }; static int fanotify_find_path(int dfd, const char __user *filename, struct path *path, unsigned int flags, __u64 mask, unsigned int obj_type) { int ret; pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, dfd, filename, flags); if (filename == NULL) { struct fd f = fdget(dfd); ret = -EBADF; if (!f.file) goto out; ret = -ENOTDIR; if ((flags & FAN_MARK_ONLYDIR) && !(S_ISDIR(file_inode(f.file)->i_mode))) { fdput(f); goto out; } *path = f.file->f_path; path_get(path); fdput(f); } else { unsigned int lookup_flags = 0; if (!(flags & FAN_MARK_DONT_FOLLOW)) lookup_flags |= LOOKUP_FOLLOW; if (flags & FAN_MARK_ONLYDIR) lookup_flags |= LOOKUP_DIRECTORY; ret = user_path_at(dfd, filename, lookup_flags, path); if (ret) goto out; } /* you can only watch an inode if you have read permissions on it */ ret = inode_permission(path->dentry->d_inode, MAY_READ); if (ret) { path_put(path); goto out; } ret = security_path_notify(path, mask, obj_type); if (ret) path_put(path); out: return ret; } static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, __u32 mask, unsigned int flags, __u32 umask, int *destroy) { __u32 oldmask = 0; /* umask bits cannot be removed by user */ mask &= ~umask; spin_lock(&fsn_mark->lock); if (!(flags & FAN_MARK_IGNORED_MASK)) { oldmask = fsn_mark->mask; fsn_mark->mask &= ~mask; } else { fsn_mark->ignored_mask &= ~mask; } /* * We need to keep the mark around even if remaining mask cannot * result in any events (e.g. mask == FAN_ONDIR) to support incremenal * changes to the mask. * Destroy mark when only umask bits remain. */ *destroy = !((fsn_mark->mask | fsn_mark->ignored_mask) & ~umask); spin_unlock(&fsn_mark->lock); return mask & oldmask; } static int fanotify_remove_mark(struct fsnotify_group *group, fsnotify_connp_t *connp, __u32 mask, unsigned int flags, __u32 umask) { struct fsnotify_mark *fsn_mark = NULL; __u32 removed; int destroy_mark; mutex_lock(&group->mark_mutex); fsn_mark = fsnotify_find_mark(connp, group); if (!fsn_mark) { mutex_unlock(&group->mark_mutex); return -ENOENT; } removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, umask, &destroy_mark); if (removed & fsnotify_conn_mask(fsn_mark->connector)) fsnotify_recalc_mask(fsn_mark->connector); if (destroy_mark) fsnotify_detach_mark(fsn_mark); mutex_unlock(&group->mark_mutex); if (destroy_mark) fsnotify_free_mark(fsn_mark); /* matches the fsnotify_find_mark() */ fsnotify_put_mark(fsn_mark); return 0; } static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt, __u32 mask, unsigned int flags, __u32 umask) { return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, mask, flags, umask); } static int fanotify_remove_sb_mark(struct fsnotify_group *group, struct super_block *sb, __u32 mask, unsigned int flags, __u32 umask) { return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, flags, umask); } static int fanotify_remove_inode_mark(struct fsnotify_group *group, struct inode *inode, __u32 mask, unsigned int flags, __u32 umask) { return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask, flags, umask); } static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, __u32 mask, unsigned int flags) { __u32 oldmask = -1; spin_lock(&fsn_mark->lock); if (!(flags & FAN_MARK_IGNORED_MASK)) { oldmask = fsn_mark->mask; fsn_mark->mask |= mask; } else { fsn_mark->ignored_mask |= mask; if (flags & FAN_MARK_IGNORED_SURV_MODIFY) fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; } spin_unlock(&fsn_mark->lock); return mask & ~oldmask; } static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, fsnotify_connp_t *connp, unsigned int type, __kernel_fsid_t *fsid) { struct fsnotify_mark *mark; int ret; if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) return ERR_PTR(-ENOSPC); mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!mark) return ERR_PTR(-ENOMEM); fsnotify_init_mark(mark, group); ret = fsnotify_add_mark_locked(mark, connp, type, 0, fsid); if (ret) { fsnotify_put_mark(mark); return ERR_PTR(ret); } return mark; } static int fanotify_add_mark(struct fsnotify_group *group, fsnotify_connp_t *connp, unsigned int type, __u32 mask, unsigned int flags, __kernel_fsid_t *fsid) { struct fsnotify_mark *fsn_mark; __u32 added; mutex_lock(&group->mark_mutex); fsn_mark = fsnotify_find_mark(connp, group); if (!fsn_mark) { fsn_mark = fanotify_add_new_mark(group, connp, type, fsid); if (IS_ERR(fsn_mark)) { mutex_unlock(&group->mark_mutex); return PTR_ERR(fsn_mark); } } added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); if (added & ~fsnotify_conn_mask(fsn_mark->connector)) fsnotify_recalc_mask(fsn_mark->connector); mutex_unlock(&group->mark_mutex); fsnotify_put_mark(fsn_mark); return 0; } static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt, __u32 mask, unsigned int flags, __kernel_fsid_t *fsid) { return fanotify_add_mark(group, &real_mount(mnt)->mnt_fsnotify_marks, FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags, fsid); } static int fanotify_add_sb_mark(struct fsnotify_group *group, struct super_block *sb, __u32 mask, unsigned int flags, __kernel_fsid_t *fsid) { return fanotify_add_mark(group, &sb->s_fsnotify_marks, FSNOTIFY_OBJ_TYPE_SB, mask, flags, fsid); } static int fanotify_add_inode_mark(struct fsnotify_group *group, struct inode *inode, __u32 mask, unsigned int flags, __kernel_fsid_t *fsid) { pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); /* * If some other task has this inode open for write we should not add * an ignored mark, unless that ignored mark is supposed to survive * modification changes anyway. */ if ((flags & FAN_MARK_IGNORED_MASK) && !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && inode_is_open_for_write(inode)) return 0; return fanotify_add_mark(group, &inode->i_fsnotify_marks, FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid); } static struct fsnotify_event *fanotify_alloc_overflow_event(void) { struct fanotify_event *oevent; oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT); if (!oevent) return NULL; fanotify_init_event(oevent, 0, FS_Q_OVERFLOW); oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW; return &oevent->fse; } /* fanotify syscalls */ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) { struct fsnotify_group *group; int f_flags, fd; struct user_struct *user; unsigned int fid_mode = flags & FANOTIFY_FID_BITS; unsigned int class = flags & FANOTIFY_CLASS_BITS; pr_debug("%s: flags=%x event_f_flags=%x\n", __func__, flags, event_f_flags); if (!capable(CAP_SYS_ADMIN)) return -EPERM; #ifdef CONFIG_AUDITSYSCALL if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT)) #else if (flags & ~FANOTIFY_INIT_FLAGS) #endif return -EINVAL; if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) return -EINVAL; switch (event_f_flags & O_ACCMODE) { case O_RDONLY: case O_RDWR: case O_WRONLY: break; default: return -EINVAL; } if (fid_mode && class != FAN_CLASS_NOTIF) return -EINVAL; /* * Child name is reported with parent fid so requires dir fid. * We can report both child fid and dir fid with or without name. */ if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID)) return -EINVAL; user = get_current_user(); if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { free_uid(user); return -EMFILE; } f_flags = O_RDWR | FMODE_NONOTIFY; if (flags & FAN_CLOEXEC) f_flags |= O_CLOEXEC; if (flags & FAN_NONBLOCK) f_flags |= O_NONBLOCK; /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ group = fsnotify_alloc_group(&fanotify_fsnotify_ops); if (IS_ERR(group)) { free_uid(user); return PTR_ERR(group); } group->fanotify_data.user = user; group->fanotify_data.flags = flags; atomic_inc(&user->fanotify_listeners); group->memcg = get_mem_cgroup_from_mm(current->mm); group->overflow_event = fanotify_alloc_overflow_event(); if (unlikely(!group->overflow_event)) { fd = -ENOMEM; goto out_destroy_group; } if (force_o_largefile()) event_f_flags |= O_LARGEFILE; group->fanotify_data.f_flags = event_f_flags; init_waitqueue_head(&group->fanotify_data.access_waitq); INIT_LIST_HEAD(&group->fanotify_data.access_list); switch (class) { case FAN_CLASS_NOTIF: group->priority = FS_PRIO_0; break; case FAN_CLASS_CONTENT: group->priority = FS_PRIO_1; break; case FAN_CLASS_PRE_CONTENT: group->priority = FS_PRIO_2; break; default: fd = -EINVAL; goto out_destroy_group; } if (flags & FAN_UNLIMITED_QUEUE) { fd = -EPERM; if (!capable(CAP_SYS_ADMIN)) goto out_destroy_group; group->max_events = UINT_MAX; } else { group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; } if (flags & FAN_UNLIMITED_MARKS) { fd = -EPERM; if (!capable(CAP_SYS_ADMIN)) goto out_destroy_group; group->fanotify_data.max_marks = UINT_MAX; } else { group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; } if (flags & FAN_ENABLE_AUDIT) { fd = -EPERM; if (!capable(CAP_AUDIT_WRITE)) goto out_destroy_group; } fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); if (fd < 0) goto out_destroy_group; return fd; out_destroy_group: fsnotify_destroy_group(group); return fd; } /* Check if filesystem can encode a unique fid */ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid) { __kernel_fsid_t root_fsid; int err; /* * Make sure path is not in filesystem with zero fsid (e.g. tmpfs). */ err = vfs_get_fsid(path->dentry, fsid); if (err) return err; if (!fsid->val[0] && !fsid->val[1]) return -ENODEV; /* * Make sure path is not inside a filesystem subvolume (e.g. btrfs) * which uses a different fsid than sb root. */ err = vfs_get_fsid(path->dentry->d_sb->s_root, &root_fsid); if (err) return err; if (root_fsid.val[0] != fsid->val[0] || root_fsid.val[1] != fsid->val[1]) return -EXDEV; /* * We need to make sure that the file system supports at least * encoding a file handle so user can use name_to_handle_at() to * compare fid returned with event to the file handle of watched * objects. However, name_to_handle_at() requires that the * filesystem also supports decoding file handles. */ if (!path->dentry->d_sb->s_export_op || !path->dentry->d_sb->s_export_op->fh_to_dentry) return -EOPNOTSUPP; return 0; } static int fanotify_events_supported(struct path *path, __u64 mask) { /* * 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; return 0; } static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, int dfd, const char __user *pathname) { struct inode *inode = NULL; struct vfsmount *mnt = NULL; struct fsnotify_group *group; struct fd f; struct path path; __kernel_fsid_t __fsid, *fsid = NULL; u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS; unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS; bool ignored = flags & FAN_MARK_IGNORED_MASK; unsigned int obj_type, fid_mode; u32 umask = 0; int ret; pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", __func__, fanotify_fd, flags, dfd, pathname, mask); /* we only use the lower 32 bits as of right now. */ if (mask & ((__u64)0xffffffff << 32)) return -EINVAL; if (flags & ~FANOTIFY_MARK_FLAGS) return -EINVAL; switch (mark_type) { case FAN_MARK_INODE: obj_type = FSNOTIFY_OBJ_TYPE_INODE; break; case FAN_MARK_MOUNT: obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT; break; case FAN_MARK_FILESYSTEM: obj_type = FSNOTIFY_OBJ_TYPE_SB; break; default: return -EINVAL; } switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { case FAN_MARK_ADD: case FAN_MARK_REMOVE: if (!mask) return -EINVAL; break; case FAN_MARK_FLUSH: if (flags & ~(FANOTIFY_MARK_TYPE_BITS | FAN_MARK_FLUSH)) return -EINVAL; break; default: return -EINVAL; } if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) valid_mask |= FANOTIFY_PERM_EVENTS; if (mask & ~valid_mask) return -EINVAL; /* Event flags (ONDIR, ON_CHILD) are meaningless in ignored mask */ if (ignored) mask &= ~FANOTIFY_EVENT_FLAGS; f = fdget(fanotify_fd); if (unlikely(!f.file)) return -EBADF; /* verify that this is indeed an fanotify instance */ ret = -EINVAL; if (unlikely(f.file->f_op != &fanotify_fops)) goto fput_and_out; group = f.file->private_data; /* * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not * allowed to set permissions events. */ ret = -EINVAL; if (mask & FANOTIFY_PERM_EVENTS && group->priority == FS_PRIO_0) goto fput_and_out; /* * Events with data type inode do not carry enough information to report * event->fd, so we do not allow setting a mask for inode events unless * group supports reporting fid. * inode events are not supported on a mount mark, because they do not * carry enough information (i.e. path) to be filtered by mount point. */ fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); if (mask & FANOTIFY_INODE_EVENTS && (!fid_mode || mark_type == FAN_MARK_MOUNT)) goto fput_and_out; if (flags & FAN_MARK_FLUSH) { ret = 0; if (mark_type == FAN_MARK_MOUNT) fsnotify_clear_vfsmount_marks_by_group(group); else if (mark_type == FAN_MARK_FILESYSTEM) fsnotify_clear_sb_marks_by_group(group); else fsnotify_clear_inode_marks_by_group(group); goto fput_and_out; } ret = fanotify_find_path(dfd, pathname, &path, flags, (mask & ALL_FSNOTIFY_EVENTS), obj_type); if (ret) goto fput_and_out; if (flags & FAN_MARK_ADD) { ret = fanotify_events_supported(&path, mask); if (ret) goto path_put_and_out; } if (fid_mode) { ret = fanotify_test_fid(&path, &__fsid); if (ret) goto path_put_and_out; fsid = &__fsid; } /* inode held in place by reference to path; group by fget on fd */ if (mark_type == FAN_MARK_INODE) inode = path.dentry->d_inode; else mnt = path.mnt; /* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */ if (mnt || !S_ISDIR(inode->i_mode)) { mask &= ~FAN_EVENT_ON_CHILD; umask = FAN_EVENT_ON_CHILD; /* * If group needs to report parent fid, register for getting * events with parent/name info for non-directory. */ if ((fid_mode & FAN_REPORT_DIR_FID) && (flags & FAN_MARK_ADD) && !ignored) mask |= FAN_EVENT_ON_CHILD; } /* create/update an inode mark */ switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) { case FAN_MARK_ADD: if (mark_type == FAN_MARK_MOUNT) ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags, fsid); else if (mark_type == FAN_MARK_FILESYSTEM) ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask, flags, fsid); else ret = fanotify_add_inode_mark(group, inode, mask, flags, fsid); break; case FAN_MARK_REMOVE: if (mark_type == FAN_MARK_MOUNT) ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags, umask); else if (mark_type == FAN_MARK_FILESYSTEM) ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask, flags, umask); else ret = fanotify_remove_inode_mark(group, inode, mask, flags, umask); break; default: ret = -EINVAL; } path_put_and_out: path_put(&path); fput_and_out: fdput(f); return ret; } 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); } #ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE6(fanotify_mark, int, fanotify_fd, unsigned int, flags, __u32, mask0, __u32, mask1, int, dfd, const char __user *, pathname) { return do_fanotify_mark(fanotify_fd, flags, #ifdef __BIG_ENDIAN ((__u64)mask0 << 32) | mask1, #else ((__u64)mask1 << 32) | mask0, #endif dfd, pathname); } #endif /* * fanotify_user_setup - Our initialization function. Note that we cannot return * error because we have compiled-in VFS hooks. So an (unlikely) failure here * must result in panic(). */ static int __init fanotify_user_setup(void) { BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 10); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9); fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC|SLAB_ACCOUNT); fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event, SLAB_PANIC); fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_event, SLAB_PANIC); if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) { fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event, SLAB_PANIC); } return 0; } device_initcall(fanotify_user_setup);