/* * fs/inotify_user.c - inotify support for userspace * * Authors: * John McCutchan * Robert Love * * Copyright (C) 2005 John McCutchan * Copyright 2006 Hewlett-Packard Development Company, L.P. * * Copyright (C) 2009 Eric Paris * inotify was largely rewriten to make use of the fsnotify infrastructure * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2, or (at your option) any * later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */ #include #include /* struct inode */ #include #include #include /* module_init */ #include #include /* roundup() */ #include /* LOOKUP_FOLLOW */ #include /* struct user */ #include /* struct kmem_cache */ #include #include #include #include #include #include #include "inotify.h" #include /* these are configurable via /proc/sys/fs/inotify/ */ static int inotify_max_user_instances __read_mostly; static int inotify_max_queued_events __read_mostly; static int inotify_max_user_watches __read_mostly; static struct kmem_cache *inotify_inode_mark_cachep __read_mostly; struct kmem_cache *event_priv_cachep __read_mostly; #ifdef CONFIG_SYSCTL #include static int zero; ctl_table inotify_table[] = { { .procname = "max_user_instances", .data = &inotify_max_user_instances, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = &zero, }, { .procname = "max_user_watches", .data = &inotify_max_user_watches, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = &zero, }, { .procname = "max_queued_events", .data = &inotify_max_queued_events, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = &zero }, { } }; #endif /* CONFIG_SYSCTL */ static inline __u32 inotify_arg_to_mask(u32 arg) { __u32 mask; /* * everything should accept their own ignored, cares about children, * and should receive events when the inode is unmounted */ mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT); /* mask off the flags used to open the fd */ mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK)); return mask; } static inline u32 inotify_mask_to_arg(__u32 mask) { return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | IN_Q_OVERFLOW); } /* intofiy userspace file descriptor functions */ static unsigned int inotify_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; } /* * Get an inotify_kernel_event if one exists and is small * enough to fit in "count". Return an error pointer if * not large enough. * * Called with the group->notification_mutex held. */ static struct fsnotify_event *get_one_event(struct fsnotify_group *group, size_t count) { size_t event_size = sizeof(struct inotify_event); struct fsnotify_event *event; if (fsnotify_notify_queue_is_empty(group)) return NULL; event = fsnotify_peek_notify_event(group); pr_debug("%s: group=%p event=%p\n", __func__, group, event); if (event->name_len) event_size += roundup(event->name_len + 1, event_size); if (event_size > count) return ERR_PTR(-EINVAL); /* held the notification_mutex the whole time, so this is the * same event we peeked above */ fsnotify_remove_notify_event(group); return event; } /* * Copy an event to user space, returning how much we copied. * * We already checked that the event size is smaller than the * buffer we had in "get_one_event()" above. */ static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fsnotify_event *event, char __user *buf) { struct inotify_event inotify_event; struct fsnotify_event_private_data *fsn_priv; struct inotify_event_private_data *priv; size_t event_size = sizeof(struct inotify_event); size_t name_len = 0; pr_debug("%s: group=%p event=%p\n", __func__, group, event); /* we get the inotify watch descriptor from the event private data */ spin_lock(&event->lock); fsn_priv = fsnotify_remove_priv_from_event(group, event); spin_unlock(&event->lock); if (!fsn_priv) inotify_event.wd = -1; else { priv = container_of(fsn_priv, struct inotify_event_private_data, fsnotify_event_priv_data); inotify_event.wd = priv->wd; inotify_free_event_priv(fsn_priv); } /* * round up event->name_len so it is a multiple of event_size * plus an extra byte for the terminating '\0'. */ if (event->name_len) name_len = roundup(event->name_len + 1, event_size); inotify_event.len = name_len; inotify_event.mask = inotify_mask_to_arg(event->mask); inotify_event.cookie = event->sync_cookie; /* send the main event */ if (copy_to_user(buf, &inotify_event, event_size)) return -EFAULT; buf += event_size; /* * fsnotify only stores the pathname, so here we have to send the pathname * and then pad that pathname out to a multiple of sizeof(inotify_event) * with zeros. I get my zeros from the nul_inotify_event. */ if (name_len) { unsigned int len_to_zero = name_len - event->name_len; /* copy the path name */ if (copy_to_user(buf, event->file_name, event->name_len)) return -EFAULT; buf += event->name_len; /* fill userspace with 0's */ if (clear_user(buf, len_to_zero)) return -EFAULT; buf += len_to_zero; event_size += name_len; } return event_size; } static ssize_t inotify_read(struct file *file, char __user *buf, size_t count, loff_t *pos) { struct fsnotify_group *group; struct fsnotify_event *kevent; char __user *start; int ret; DEFINE_WAIT(wait); start = buf; group = file->private_data; 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); pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent); if (kevent) { ret = PTR_ERR(kevent); if (IS_ERR(kevent)) break; ret = copy_event_to_user(group, kevent, buf); fsnotify_put_event(kevent); if (ret < 0) break; buf += ret; count -= ret; continue; } ret = -EAGAIN; if (file->f_flags & O_NONBLOCK) break; ret = -EINTR; 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 int inotify_release(struct inode *ignored, struct file *file) { struct fsnotify_group *group = file->private_data; pr_debug("%s: group=%p\n", __func__, group); if (file->f_flags & FASYNC) fsnotify_fasync(-1, file, 0); /* free this group, matching get was inotify_init->fsnotify_obtain_group */ fsnotify_destroy_group(group); return 0; } static long inotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct fsnotify_group *group; struct fsnotify_event_holder *holder; struct fsnotify_event *event; void __user *p; int ret = -ENOTTY; size_t send_len = 0; group = file->private_data; p = (void __user *) arg; pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd); switch (cmd) { case FIONREAD: mutex_lock(&group->notification_mutex); list_for_each_entry(holder, &group->notification_list, event_list) { event = holder->event; send_len += sizeof(struct inotify_event); if (event->name_len) send_len += roundup(event->name_len + 1, sizeof(struct inotify_event)); } mutex_unlock(&group->notification_mutex); ret = put_user(send_len, (int __user *) p); break; } return ret; } static const struct file_operations inotify_fops = { .poll = inotify_poll, .read = inotify_read, .fasync = fsnotify_fasync, .release = inotify_release, .unlocked_ioctl = inotify_ioctl, .compat_ioctl = inotify_ioctl, .llseek = noop_llseek, }; /* * find_inode - resolve a user-given path to a specific inode */ static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags) { int error; error = user_path_at(AT_FDCWD, dirname, flags, path); if (error) return error; /* you can only watch an inode if you have read permissions on it */ error = inode_permission(path->dentry->d_inode, MAY_READ); if (error) path_put(path); return error; } static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock, int *last_wd, struct inotify_inode_mark *i_mark) { int ret; do { if (unlikely(!idr_pre_get(idr, GFP_KERNEL))) return -ENOMEM; spin_lock(idr_lock); ret = idr_get_new_above(idr, i_mark, *last_wd + 1, &i_mark->wd); /* we added the mark to the idr, take a reference */ if (!ret) { *last_wd = i_mark->wd; fsnotify_get_mark(&i_mark->fsn_mark); } spin_unlock(idr_lock); } while (ret == -EAGAIN); return ret; } static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group, int wd) { struct idr *idr = &group->inotify_data.idr; spinlock_t *idr_lock = &group->inotify_data.idr_lock; struct inotify_inode_mark *i_mark; assert_spin_locked(idr_lock); i_mark = idr_find(idr, wd); if (i_mark) { struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark; fsnotify_get_mark(fsn_mark); /* One ref for being in the idr, one ref we just took */ BUG_ON(atomic_read(&fsn_mark->refcnt) < 2); } return i_mark; } static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group, int wd) { struct inotify_inode_mark *i_mark; spinlock_t *idr_lock = &group->inotify_data.idr_lock; spin_lock(idr_lock); i_mark = inotify_idr_find_locked(group, wd); spin_unlock(idr_lock); return i_mark; } static void do_inotify_remove_from_idr(struct fsnotify_group *group, struct inotify_inode_mark *i_mark) { struct idr *idr = &group->inotify_data.idr; spinlock_t *idr_lock = &group->inotify_data.idr_lock; int wd = i_mark->wd; assert_spin_locked(idr_lock); idr_remove(idr, wd); /* removed from the idr, drop that ref */ fsnotify_put_mark(&i_mark->fsn_mark); } /* * Remove the mark from the idr (if present) and drop the reference * on the mark because it was in the idr. */ static void inotify_remove_from_idr(struct fsnotify_group *group, struct inotify_inode_mark *i_mark) { spinlock_t *idr_lock = &group->inotify_data.idr_lock; struct inotify_inode_mark *found_i_mark = NULL; int wd; spin_lock(idr_lock); wd = i_mark->wd; /* * does this i_mark think it is in the idr? we shouldn't get called * if it wasn't.... */ if (wd == -1) { WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode); goto out; } /* Lets look in the idr to see if we find it */ found_i_mark = inotify_idr_find_locked(group, wd); if (unlikely(!found_i_mark)) { WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode); goto out; } /* * We found an mark in the idr at the right wd, but it's * not the mark we were told to remove. eparis seriously * fucked up somewhere. */ if (unlikely(found_i_mark != i_mark)) { WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p " "mark->inode=%p found_i_mark=%p found_i_mark->wd=%d " "found_i_mark->group=%p found_i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode, found_i_mark, found_i_mark->wd, found_i_mark->fsn_mark.group, found_i_mark->fsn_mark.i.inode); goto out; } /* * One ref for being in the idr * one ref held by the caller trying to kill us * one ref grabbed by inotify_idr_find */ if (unlikely(atomic_read(&i_mark->fsn_mark.refcnt) < 3)) { printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode); /* we can't really recover with bad ref cnting.. */ BUG(); } do_inotify_remove_from_idr(group, i_mark); out: /* match the ref taken by inotify_idr_find_locked() */ if (found_i_mark) fsnotify_put_mark(&found_i_mark->fsn_mark); i_mark->wd = -1; spin_unlock(idr_lock); } /* * Send IN_IGNORED for this wd, remove this wd from the idr. */ void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group) { struct inotify_inode_mark *i_mark; struct fsnotify_event *ignored_event, *notify_event; struct inotify_event_private_data *event_priv; struct fsnotify_event_private_data *fsn_event_priv; int ret; ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL, FSNOTIFY_EVENT_NONE, NULL, 0, GFP_NOFS); if (!ignored_event) return; i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS); if (unlikely(!event_priv)) goto skip_send_ignore; fsn_event_priv = &event_priv->fsnotify_event_priv_data; fsnotify_get_group(group); fsn_event_priv->group = group; event_priv->wd = i_mark->wd; notify_event = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv, NULL); if (notify_event) { if (IS_ERR(notify_event)) ret = PTR_ERR(notify_event); else fsnotify_put_event(notify_event); inotify_free_event_priv(fsn_event_priv); } skip_send_ignore: /* matches the reference taken when the event was created */ fsnotify_put_event(ignored_event); /* remove this mark from the idr */ inotify_remove_from_idr(group, i_mark); atomic_dec(&group->inotify_data.user->inotify_watches); } /* ding dong the mark is dead */ static void inotify_free_mark(struct fsnotify_mark *fsn_mark) { struct inotify_inode_mark *i_mark; i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); kmem_cache_free(inotify_inode_mark_cachep, i_mark); } static int inotify_update_existing_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) { struct fsnotify_mark *fsn_mark; struct inotify_inode_mark *i_mark; __u32 old_mask, new_mask; __u32 mask; int add = (arg & IN_MASK_ADD); int ret; /* don't allow invalid bits: we don't want flags set */ mask = inotify_arg_to_mask(arg); if (unlikely(!(mask & IN_ALL_EVENTS))) return -EINVAL; fsn_mark = fsnotify_find_inode_mark(group, inode); if (!fsn_mark) return -ENOENT; i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); spin_lock(&fsn_mark->lock); old_mask = fsn_mark->mask; if (add) fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask)); else fsnotify_set_mark_mask_locked(fsn_mark, mask); new_mask = fsn_mark->mask; spin_unlock(&fsn_mark->lock); if (old_mask != new_mask) { /* more bits in old than in new? */ int dropped = (old_mask & ~new_mask); /* more bits in this fsn_mark than the inode's mask? */ int do_inode = (new_mask & ~inode->i_fsnotify_mask); /* update the inode with this new fsn_mark */ if (dropped || do_inode) fsnotify_recalc_inode_mask(inode); } /* return the wd */ ret = i_mark->wd; /* match the get from fsnotify_find_mark() */ fsnotify_put_mark(fsn_mark); return ret; } static int inotify_new_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) { struct inotify_inode_mark *tmp_i_mark; __u32 mask; int ret; struct idr *idr = &group->inotify_data.idr; spinlock_t *idr_lock = &group->inotify_data.idr_lock; /* don't allow invalid bits: we don't want flags set */ mask = inotify_arg_to_mask(arg); if (unlikely(!(mask & IN_ALL_EVENTS))) return -EINVAL; tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); if (unlikely(!tmp_i_mark)) return -ENOMEM; fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark); tmp_i_mark->fsn_mark.mask = mask; tmp_i_mark->wd = -1; ret = -ENOSPC; if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches) goto out_err; ret = inotify_add_to_idr(idr, idr_lock, &group->inotify_data.last_wd, tmp_i_mark); if (ret) goto out_err; /* we are on the idr, now get on the inode */ ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, NULL, 0); if (ret) { /* we failed to get on the inode, get off the idr */ inotify_remove_from_idr(group, tmp_i_mark); goto out_err; } /* increment the number of watches the user has */ atomic_inc(&group->inotify_data.user->inotify_watches); /* return the watch descriptor for this new mark */ ret = tmp_i_mark->wd; out_err: /* match the ref from fsnotify_init_mark() */ fsnotify_put_mark(&tmp_i_mark->fsn_mark); return ret; } static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) { int ret = 0; retry: /* try to update and existing watch with the new arg */ ret = inotify_update_existing_watch(group, inode, arg); /* no mark present, try to add a new one */ if (ret == -ENOENT) ret = inotify_new_watch(group, inode, arg); /* * inotify_new_watch could race with another thread which did an * inotify_new_watch between the update_existing and the add watch * here, go back and try to update an existing mark again. */ if (ret == -EEXIST) goto retry; return ret; } static struct fsnotify_group *inotify_new_group(unsigned int max_events) { struct fsnotify_group *group; group = fsnotify_alloc_group(&inotify_fsnotify_ops); if (IS_ERR(group)) return group; group->max_events = max_events; spin_lock_init(&group->inotify_data.idr_lock); idr_init(&group->inotify_data.idr); group->inotify_data.last_wd = 0; group->inotify_data.user = get_current_user(); if (atomic_inc_return(&group->inotify_data.user->inotify_devs) > inotify_max_user_instances) { fsnotify_destroy_group(group); return ERR_PTR(-EMFILE); } return group; } /* inotify syscalls */ SYSCALL_DEFINE1(inotify_init1, int, flags) { struct fsnotify_group *group; int ret; /* Check the IN_* constants for consistency. */ BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) return -EINVAL; /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ group = inotify_new_group(inotify_max_queued_events); if (IS_ERR(group)) return PTR_ERR(group); ret = anon_inode_getfd("inotify", &inotify_fops, group, O_RDONLY | flags); if (ret < 0) fsnotify_destroy_group(group); return ret; } SYSCALL_DEFINE0(inotify_init) { return sys_inotify_init1(0); } SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, u32, mask) { struct fsnotify_group *group; struct inode *inode; struct path path; struct file *filp; int ret, fput_needed; unsigned flags = 0; filp = fget_light(fd, &fput_needed); if (unlikely(!filp)) return -EBADF; /* verify that this is indeed an inotify instance */ if (unlikely(filp->f_op != &inotify_fops)) { ret = -EINVAL; goto fput_and_out; } if (!(mask & IN_DONT_FOLLOW)) flags |= LOOKUP_FOLLOW; if (mask & IN_ONLYDIR) flags |= LOOKUP_DIRECTORY; ret = inotify_find_inode(pathname, &path, flags); if (ret) goto fput_and_out; /* inode held in place by reference to path; group by fget on fd */ inode = path.dentry->d_inode; group = filp->private_data; /* create/update an inode mark */ ret = inotify_update_watch(group, inode, mask); path_put(&path); fput_and_out: fput_light(filp, fput_needed); return ret; } SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) { struct fsnotify_group *group; struct inotify_inode_mark *i_mark; struct file *filp; int ret = 0, fput_needed; filp = fget_light(fd, &fput_needed); if (unlikely(!filp)) return -EBADF; /* verify that this is indeed an inotify instance */ ret = -EINVAL; if (unlikely(filp->f_op != &inotify_fops)) goto out; group = filp->private_data; ret = -EINVAL; i_mark = inotify_idr_find(group, wd); if (unlikely(!i_mark)) goto out; ret = 0; fsnotify_destroy_mark(&i_mark->fsn_mark, group); /* match ref taken by inotify_idr_find */ fsnotify_put_mark(&i_mark->fsn_mark); out: fput_light(filp, fput_needed); return ret; } /* * inotify_user_setup - Our initialization function. Note that we cannot return * error because we have compiled-in VFS hooks. So an (unlikely) failure here * must result in panic(). */ static int __init inotify_user_setup(void) { BUILD_BUG_ON(IN_ACCESS != FS_ACCESS); BUILD_BUG_ON(IN_MODIFY != FS_MODIFY); BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB); BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE); BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); BUILD_BUG_ON(IN_OPEN != FS_OPEN); BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM); BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO); BUILD_BUG_ON(IN_CREATE != FS_CREATE); BUILD_BUG_ON(IN_DELETE != FS_DELETE); BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF); BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF); BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT); BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW); BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED); BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK); BUILD_BUG_ON(IN_ISDIR != FS_ISDIR); BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT); BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21); inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC); event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC); inotify_max_queued_events = 16384; inotify_max_user_instances = 128; inotify_max_user_watches = 8192; return 0; } module_init(inotify_user_setup);