#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "../../mount.h" #include "../fdinfo.h" #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 #define FANOTIFY_DEFAULT_MAX_MARKS 8192 #define FANOTIFY_DEFAULT_MAX_LISTENERS 128 extern const struct fsnotify_ops fanotify_fsnotify_ops; static struct kmem_cache *fanotify_mark_cache __read_mostly; static struct kmem_cache *fanotify_response_event_cache __read_mostly; struct fanotify_response_event { struct list_head list; __s32 fd; struct fsnotify_event *event; }; /* * Get an fsnotify notification event if one exists and is small * enough to fit in "count". Return an error pointer if the count * is not large enough. * * Called with the group->notification_mutex held. */ static struct fsnotify_event *get_one_event(struct fsnotify_group *group, size_t count) { BUG_ON(!mutex_is_locked(&group->notification_mutex)); pr_debug("%s: group=%p count=%zd\n", __func__, group, count); if (fsnotify_notify_queue_is_empty(group)) return NULL; if (FAN_EVENT_METADATA_LEN > count) return ERR_PTR(-EINVAL); /* held the notification_mutex the whole time, so this is the * same event we peeked above */ return fsnotify_remove_notify_event(group); } static int create_fd(struct fsnotify_group *group, struct fsnotify_event *event, struct file **file) { int client_fd; struct file *new_file; pr_debug("%s: group=%p event=%p\n", __func__, group, event); client_fd = get_unused_fd(); if (client_fd < 0) return client_fd; if (event->data_type != FSNOTIFY_EVENT_PATH) { WARN_ON(1); put_unused_fd(client_fd); return -EINVAL; } /* * we need a new file handle for the userspace program so it can read even if it was * originally opened O_WRONLY. */ /* it's possible this event was an overflow event. in that case dentry and mnt * are NULL; That's fine, just don't call dentry open */ if (event->path.dentry && event->path.mnt) new_file = dentry_open(&event->path, group->fanotify_data.f_flags | FMODE_NONOTIFY, current_cred()); else new_file = ERR_PTR(-EOVERFLOW); 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; } static int fill_event_metadata(struct fsnotify_group *group, struct fanotify_event_metadata *metadata, struct fsnotify_event *event, struct file **file) { int ret = 0; pr_debug("%s: group=%p metadata=%p event=%p\n", __func__, group, metadata, event); *file = NULL; metadata->event_len = FAN_EVENT_METADATA_LEN; metadata->metadata_len = FAN_EVENT_METADATA_LEN; metadata->vers = FANOTIFY_METADATA_VERSION; metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS; metadata->pid = pid_vnr(event->tgid); if (unlikely(event->mask & FAN_Q_OVERFLOW)) metadata->fd = FAN_NOFD; else { metadata->fd = create_fd(group, event, file); if (metadata->fd < 0) ret = metadata->fd; } return ret; } #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS static struct fanotify_response_event *dequeue_re(struct fsnotify_group *group, __s32 fd) { struct fanotify_response_event *re, *return_re = NULL; mutex_lock(&group->fanotify_data.access_mutex); list_for_each_entry(re, &group->fanotify_data.access_list, list) { if (re->fd != fd) continue; list_del_init(&re->list); return_re = re; break; } mutex_unlock(&group->fanotify_data.access_mutex); pr_debug("%s: found return_re=%p\n", __func__, return_re); return return_re; } static int process_access_response(struct fsnotify_group *group, struct fanotify_response *response_struct) { struct fanotify_response_event *re; __s32 fd = response_struct->fd; __u32 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) { case FAN_ALLOW: case FAN_DENY: break; default: return -EINVAL; } if (fd < 0) return -EINVAL; re = dequeue_re(group, fd); if (!re) return -ENOENT; re->event->response = response; wake_up(&group->fanotify_data.access_waitq); kmem_cache_free(fanotify_response_event_cache, re); return 0; } static int prepare_for_access_response(struct fsnotify_group *group, struct fsnotify_event *event, __s32 fd) { struct fanotify_response_event *re; if (!(event->mask & FAN_ALL_PERM_EVENTS)) return 0; re = kmem_cache_alloc(fanotify_response_event_cache, GFP_KERNEL); if (!re) return -ENOMEM; re->event = event; re->fd = fd; mutex_lock(&group->fanotify_data.access_mutex); if (atomic_read(&group->fanotify_data.bypass_perm)) { mutex_unlock(&group->fanotify_data.access_mutex); kmem_cache_free(fanotify_response_event_cache, re); event->response = FAN_ALLOW; return 0; } list_add_tail(&re->list, &group->fanotify_data.access_list); mutex_unlock(&group->fanotify_data.access_mutex); return 0; } #else static int prepare_for_access_response(struct fsnotify_group *group, struct fsnotify_event *event, __s32 fd) { return 0; } #endif static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fsnotify_event *event, char __user *buf) { struct fanotify_event_metadata fanotify_event_metadata; struct file *f; int fd, ret; pr_debug("%s: group=%p event=%p\n", __func__, group, event); ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f); if (ret < 0) goto out; fd = fanotify_event_metadata.fd; ret = -EFAULT; if (copy_to_user(buf, &fanotify_event_metadata, fanotify_event_metadata.event_len)) goto out_close_fd; ret = prepare_for_access_response(group, event, fd); if (ret) goto out_close_fd; if (fd != FAN_NOFD) fd_install(fd, f); return fanotify_event_metadata.event_len; out_close_fd: if (fd != FAN_NOFD) { put_unused_fd(fd); fput(f); } out: #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS if (event->mask & FAN_ALL_PERM_EVENTS) { event->response = FAN_DENY; wake_up(&group->fanotify_data.access_waitq); } #endif return ret; } /* intofiy userspace file descriptor functions */ static unsigned int fanotify_poll(struct file *file, poll_table *wait) { struct fsnotify_group *group = file->private_data; int ret = 0; poll_wait(file, &group->notification_waitq, wait); mutex_lock(&group->notification_mutex); if (!fsnotify_notify_queue_is_empty(group)) ret = POLLIN | POLLRDNORM; mutex_unlock(&group->notification_mutex); return ret; } static ssize_t fanotify_read(struct file *file, char __user *buf, size_t count, loff_t *pos) { struct fsnotify_group *group; struct fsnotify_event *kevent; char __user *start; int ret; DEFINE_WAIT(wait); start = buf; group = file->private_data; pr_debug("%s: group=%p\n", __func__, group); while (1) { prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE); mutex_lock(&group->notification_mutex); kevent = get_one_event(group, count); mutex_unlock(&group->notification_mutex); if (kevent) { ret = PTR_ERR(kevent); if (IS_ERR(kevent)) break; ret = copy_event_to_user(group, kevent, buf); fsnotify_put_event(kevent); if (ret < 0) break; buf += ret; count -= ret; continue; } ret = -EAGAIN; if (file->f_flags & O_NONBLOCK) break; ret = -ERESTARTSYS; if (signal_pending(current)) break; if (start != buf) break; schedule(); } finish_wait(&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) { #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS struct fanotify_response response = { .fd = -1, .response = -1 }; struct fsnotify_group *group; int ret; group = file->private_data; if (count > sizeof(response)) 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; #else return -EINVAL; #endif } static int fanotify_release(struct inode *ignored, struct file *file) { struct fsnotify_group *group = file->private_data; #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS struct fanotify_response_event *re, *lre; mutex_lock(&group->fanotify_data.access_mutex); atomic_inc(&group->fanotify_data.bypass_perm); list_for_each_entry_safe(re, lre, &group->fanotify_data.access_list, list) { pr_debug("%s: found group=%p re=%p event=%p\n", __func__, group, re, re->event); list_del_init(&re->list); re->event->response = FAN_ALLOW; kmem_cache_free(fanotify_response_event_cache, re); } mutex_unlock(&group->fanotify_data.access_mutex); wake_up(&group->fanotify_data.access_waitq); #endif /* 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_holder *holder; void __user *p; int ret = -ENOTTY; size_t send_len = 0; group = file->private_data; p = (void __user *) arg; switch (cmd) { case FIONREAD: mutex_lock(&group->notification_mutex); list_for_each_entry(holder, &group->notification_list, event_list) send_len += FAN_EVENT_METADATA_LEN; mutex_unlock(&group->notification_mutex); 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 = fanotify_ioctl, .llseek = noop_llseek, }; static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) { kmem_cache_free(fanotify_mark_cache, fsn_mark); } static int fanotify_find_path(int dfd, const char __user *filename, struct path *path, unsigned int flags) { 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); out: return ret; } static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, __u32 mask, unsigned int flags, int *destroy) { __u32 oldmask; spin_lock(&fsn_mark->lock); if (!(flags & FAN_MARK_IGNORED_MASK)) { oldmask = fsn_mark->mask; fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask)); } else { oldmask = fsn_mark->ignored_mask; fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask)); } spin_unlock(&fsn_mark->lock); *destroy = !(oldmask & ~mask); return mask & oldmask; } static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt, __u32 mask, unsigned int flags) { struct fsnotify_mark *fsn_mark = NULL; __u32 removed; int destroy_mark; fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); if (!fsn_mark) return -ENOENT; removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, &destroy_mark); if (destroy_mark) fsnotify_destroy_mark(fsn_mark, group); fsnotify_put_mark(fsn_mark); if (removed & real_mount(mnt)->mnt_fsnotify_mask) fsnotify_recalc_vfsmount_mask(mnt); return 0; } static int fanotify_remove_inode_mark(struct fsnotify_group *group, struct inode *inode, __u32 mask, unsigned int flags) { struct fsnotify_mark *fsn_mark = NULL; __u32 removed; int destroy_mark; fsn_mark = fsnotify_find_inode_mark(group, inode); if (!fsn_mark) return -ENOENT; removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, &destroy_mark); if (destroy_mark) fsnotify_destroy_mark(fsn_mark, group); /* matches the fsnotify_find_inode_mark() */ fsnotify_put_mark(fsn_mark); if (removed & inode->i_fsnotify_mask) fsnotify_recalc_inode_mask(inode); return 0; } 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; fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask)); } else { __u32 tmask = fsn_mark->ignored_mask | mask; fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); if (flags & FAN_MARK_IGNORED_SURV_MODIFY) fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; } if (!(flags & FAN_MARK_ONDIR)) { __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR; fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); } spin_unlock(&fsn_mark->lock); return mask & ~oldmask; } static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt, __u32 mask, unsigned int flags) { struct fsnotify_mark *fsn_mark; __u32 added; int ret = 0; fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); if (!fsn_mark) { if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) return -ENOSPC; fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; fsnotify_init_mark(fsn_mark, fanotify_free_mark); ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0); if (ret) goto err; } added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); if (added & ~real_mount(mnt)->mnt_fsnotify_mask) fsnotify_recalc_vfsmount_mask(mnt); err: fsnotify_put_mark(fsn_mark); return ret; } static int fanotify_add_inode_mark(struct fsnotify_group *group, struct inode *inode, __u32 mask, unsigned int flags) { struct fsnotify_mark *fsn_mark; __u32 added; int ret = 0; 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) && (atomic_read(&inode->i_writecount) > 0)) return 0; fsn_mark = fsnotify_find_inode_mark(group, inode); if (!fsn_mark) { if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) return -ENOSPC; fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; fsnotify_init_mark(fsn_mark, fanotify_free_mark); ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0); if (ret) goto err; } added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); if (added & ~inode->i_fsnotify_mask) fsnotify_recalc_inode_mask(inode); err: fsnotify_put_mark(fsn_mark); return ret; } /* 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; pr_debug("%s: flags=%d event_f_flags=%d\n", __func__, flags, event_f_flags); if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (flags & ~FAN_ALL_INIT_FLAGS) 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; atomic_inc(&user->fanotify_listeners); group->fanotify_data.f_flags = event_f_flags; #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS mutex_init(&group->fanotify_data.access_mutex); init_waitqueue_head(&group->fanotify_data.access_waitq); INIT_LIST_HEAD(&group->fanotify_data.access_list); atomic_set(&group->fanotify_data.bypass_perm, 0); #endif switch (flags & FAN_ALL_CLASS_BITS) { 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; } 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; } SYSCALL_DEFINE5(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; 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 & ~FAN_ALL_MARK_FLAGS) return -EINVAL; switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { case FAN_MARK_ADD: /* fallthrough */ case FAN_MARK_REMOVE: if (!mask) return -EINVAL; case FAN_MARK_FLUSH: break; default: return -EINVAL; } if (mask & FAN_ONDIR) { flags |= FAN_MARK_ONDIR; mask &= ~FAN_ONDIR; } #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD)) #else if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD)) #endif return -EINVAL; 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 & FAN_ALL_PERM_EVENTS && group->priority == FS_PRIO_0) goto fput_and_out; ret = fanotify_find_path(dfd, pathname, &path, flags); if (ret) goto fput_and_out; /* inode held in place by reference to path; group by fget on fd */ if (!(flags & FAN_MARK_MOUNT)) inode = path.dentry->d_inode; else mnt = path.mnt; /* create/update an inode mark */ switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { case FAN_MARK_ADD: if (flags & FAN_MARK_MOUNT) ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags); else ret = fanotify_add_inode_mark(group, inode, mask, flags); break; case FAN_MARK_REMOVE: if (flags & FAN_MARK_MOUNT) ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags); else ret = fanotify_remove_inode_mark(group, inode, mask, flags); break; case FAN_MARK_FLUSH: if (flags & FAN_MARK_MOUNT) fsnotify_clear_vfsmount_marks_by_group(group); else fsnotify_clear_inode_marks_by_group(group); break; default: ret = -EINVAL; } path_put(&path); fput_and_out: fdput(f); return ret; } #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 sys_fanotify_mark(fanotify_fd, flags, #ifdef __BIG_ENDIAN ((__u64)mask1 << 32) | mask0, #else ((__u64)mask0 << 32) | mask1, #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) { fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC); fanotify_response_event_cache = KMEM_CACHE(fanotify_response_event, SLAB_PANIC); return 0; } device_initcall(fanotify_user_setup);