diff options
Diffstat (limited to 'fs/inotify_user.c')
| -rw-r--r-- | fs/inotify_user.c | 778 |
1 files changed, 0 insertions, 778 deletions
diff --git a/fs/inotify_user.c b/fs/inotify_user.c deleted file mode 100644 index 400f8064a548..000000000000 --- a/fs/inotify_user.c +++ /dev/null @@ -1,778 +0,0 @@ -/* - * fs/inotify_user.c - inotify support for userspace - * - * Authors: - * John McCutchan <ttb@tentacle.dhs.org> - * Robert Love <rml@novell.com> - * - * Copyright (C) 2005 John McCutchan - * Copyright 2006 Hewlett-Packard Development Company, L.P. - * - * 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 <linux/kernel.h> -#include <linux/sched.h> -#include <linux/slab.h> -#include <linux/fs.h> -#include <linux/file.h> -#include <linux/mount.h> -#include <linux/namei.h> -#include <linux/poll.h> -#include <linux/init.h> -#include <linux/list.h> -#include <linux/inotify.h> -#include <linux/syscalls.h> -#include <linux/magic.h> - -#include <asm/ioctls.h> - -static struct kmem_cache *watch_cachep __read_mostly; -static struct kmem_cache *event_cachep __read_mostly; - -static struct vfsmount *inotify_mnt __read_mostly; - -/* these are configurable via /proc/sys/fs/inotify/ */ -static int inotify_max_user_instances __read_mostly; -static int inotify_max_user_watches __read_mostly; -static int inotify_max_queued_events __read_mostly; - -/* - * Lock ordering: - * - * inotify_dev->up_mutex (ensures we don't re-add the same watch) - * inode->inotify_mutex (protects inode's watch list) - * inotify_handle->mutex (protects inotify_handle's watch list) - * inotify_dev->ev_mutex (protects device's event queue) - */ - -/* - * Lifetimes of the main data structures: - * - * inotify_device: Lifetime is managed by reference count, from - * sys_inotify_init() until release. Additional references can bump the count - * via get_inotify_dev() and drop the count via put_inotify_dev(). - * - * inotify_user_watch: Lifetime is from create_watch() to the receipt of an - * IN_IGNORED event from inotify, or when using IN_ONESHOT, to receipt of the - * first event, or to inotify_destroy(). - */ - -/* - * struct inotify_device - represents an inotify instance - * - * This structure is protected by the mutex 'mutex'. - */ -struct inotify_device { - wait_queue_head_t wq; /* wait queue for i/o */ - struct mutex ev_mutex; /* protects event queue */ - struct mutex up_mutex; /* synchronizes watch updates */ - struct list_head events; /* list of queued events */ - struct user_struct *user; /* user who opened this dev */ - struct inotify_handle *ih; /* inotify handle */ - struct fasync_struct *fa; /* async notification */ - atomic_t count; /* reference count */ - unsigned int queue_size; /* size of the queue (bytes) */ - unsigned int event_count; /* number of pending events */ - unsigned int max_events; /* maximum number of events */ -}; - -/* - * struct inotify_kernel_event - An inotify event, originating from a watch and - * queued for user-space. A list of these is attached to each instance of the - * device. In read(), this list is walked and all events that can fit in the - * buffer are returned. - * - * Protected by dev->ev_mutex of the device in which we are queued. - */ -struct inotify_kernel_event { - struct inotify_event event; /* the user-space event */ - struct list_head list; /* entry in inotify_device's list */ - char *name; /* filename, if any */ -}; - -/* - * struct inotify_user_watch - our version of an inotify_watch, we add - * a reference to the associated inotify_device. - */ -struct inotify_user_watch { - struct inotify_device *dev; /* associated device */ - struct inotify_watch wdata; /* inotify watch data */ -}; - -#ifdef CONFIG_SYSCTL - -#include <linux/sysctl.h> - -static int zero; - -ctl_table inotify_table[] = { - { - .ctl_name = INOTIFY_MAX_USER_INSTANCES, - .procname = "max_user_instances", - .data = &inotify_max_user_instances, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = &proc_dointvec_minmax, - .strategy = &sysctl_intvec, - .extra1 = &zero, - }, - { - .ctl_name = INOTIFY_MAX_USER_WATCHES, - .procname = "max_user_watches", - .data = &inotify_max_user_watches, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = &proc_dointvec_minmax, - .strategy = &sysctl_intvec, - .extra1 = &zero, - }, - { - .ctl_name = INOTIFY_MAX_QUEUED_EVENTS, - .procname = "max_queued_events", - .data = &inotify_max_queued_events, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = &proc_dointvec_minmax, - .strategy = &sysctl_intvec, - .extra1 = &zero - }, - { .ctl_name = 0 } -}; -#endif /* CONFIG_SYSCTL */ - -static inline void get_inotify_dev(struct inotify_device *dev) -{ - atomic_inc(&dev->count); -} - -static inline void put_inotify_dev(struct inotify_device *dev) -{ - if (atomic_dec_and_test(&dev->count)) { - atomic_dec(&dev->user->inotify_devs); - free_uid(dev->user); - kfree(dev); - } -} - -/* - * free_inotify_user_watch - cleans up the watch and its references - */ -static void free_inotify_user_watch(struct inotify_watch *w) -{ - struct inotify_user_watch *watch; - struct inotify_device *dev; - - watch = container_of(w, struct inotify_user_watch, wdata); - dev = watch->dev; - - atomic_dec(&dev->user->inotify_watches); - put_inotify_dev(dev); - kmem_cache_free(watch_cachep, watch); -} - -/* - * kernel_event - create a new kernel event with the given parameters - * - * This function can sleep. - */ -static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie, - const char *name) -{ - struct inotify_kernel_event *kevent; - - kevent = kmem_cache_alloc(event_cachep, GFP_NOFS); - if (unlikely(!kevent)) - return NULL; - - /* we hand this out to user-space, so zero it just in case */ - memset(&kevent->event, 0, sizeof(struct inotify_event)); - - kevent->event.wd = wd; - kevent->event.mask = mask; - kevent->event.cookie = cookie; - - INIT_LIST_HEAD(&kevent->list); - - if (name) { - size_t len, rem, event_size = sizeof(struct inotify_event); - - /* - * We need to pad the filename so as to properly align an - * array of inotify_event structures. Because the structure is - * small and the common case is a small filename, we just round - * up to the next multiple of the structure's sizeof. This is - * simple and safe for all architectures. - */ - len = strlen(name) + 1; - rem = event_size - len; - if (len > event_size) { - rem = event_size - (len % event_size); - if (len % event_size == 0) - rem = 0; - } - - kevent->name = kmalloc(len + rem, GFP_KERNEL); - if (unlikely(!kevent->name)) { - kmem_cache_free(event_cachep, kevent); - return NULL; - } - memcpy(kevent->name, name, len); - if (rem) - memset(kevent->name + len, 0, rem); - kevent->event.len = len + rem; - } else { - kevent->event.len = 0; - kevent->name = NULL; - } - - return kevent; -} - -/* - * inotify_dev_get_event - return the next event in the given dev's queue - * - * Caller must hold dev->ev_mutex. - */ -static inline struct inotify_kernel_event * -inotify_dev_get_event(struct inotify_device *dev) -{ - return list_entry(dev->events.next, struct inotify_kernel_event, list); -} - -/* - * inotify_dev_get_last_event - return the last event in the given dev's queue - * - * Caller must hold dev->ev_mutex. - */ -static inline struct inotify_kernel_event * -inotify_dev_get_last_event(struct inotify_device *dev) -{ - if (list_empty(&dev->events)) - return NULL; - return list_entry(dev->events.prev, struct inotify_kernel_event, list); -} - -/* - * inotify_dev_queue_event - event handler registered with core inotify, adds - * a new event to the given device - * - * Can sleep (calls kernel_event()). - */ -static void inotify_dev_queue_event(struct inotify_watch *w, u32 wd, u32 mask, - u32 cookie, const char *name, - struct inode *ignored) -{ - struct inotify_user_watch *watch; - struct inotify_device *dev; - struct inotify_kernel_event *kevent, *last; - - watch = container_of(w, struct inotify_user_watch, wdata); - dev = watch->dev; - - mutex_lock(&dev->ev_mutex); - - /* we can safely put the watch as we don't reference it while - * generating the event - */ - if (mask & IN_IGNORED || w->mask & IN_ONESHOT) - put_inotify_watch(w); /* final put */ - - /* coalescing: drop this event if it is a dupe of the previous */ - last = inotify_dev_get_last_event(dev); - if (last && last->event.mask == mask && last->event.wd == wd && - last->event.cookie == cookie) { - const char *lastname = last->name; - - if (!name && !lastname) - goto out; - if (name && lastname && !strcmp(lastname, name)) - goto out; - } - - /* the queue overflowed and we already sent the Q_OVERFLOW event */ - if (unlikely(dev->event_count > dev->max_events)) - goto out; - - /* if the queue overflows, we need to notify user space */ - if (unlikely(dev->event_count == dev->max_events)) - kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL); - else - kevent = kernel_event(wd, mask, cookie, name); - - if (unlikely(!kevent)) - goto out; - - /* queue the event and wake up anyone waiting */ - dev->event_count++; - dev->queue_size += sizeof(struct inotify_event) + kevent->event.len; - list_add_tail(&kevent->list, &dev->events); - wake_up_interruptible(&dev->wq); - kill_fasync(&dev->fa, SIGIO, POLL_IN); - -out: - mutex_unlock(&dev->ev_mutex); -} - -/* - * remove_kevent - cleans up the given kevent - * - * Caller must hold dev->ev_mutex. - */ -static void remove_kevent(struct inotify_device *dev, - struct inotify_kernel_event *kevent) -{ - list_del(&kevent->list); - - dev->event_count--; - dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len; -} - -/* - * free_kevent - frees the given kevent. - */ -static void free_kevent(struct inotify_kernel_event *kevent) -{ - kfree(kevent->name); - kmem_cache_free(event_cachep, kevent); -} - -/* - * inotify_dev_event_dequeue - destroy an event on the given device - * - * Caller must hold dev->ev_mutex. - */ -static void inotify_dev_event_dequeue(struct inotify_device *dev) -{ - if (!list_empty(&dev->events)) { - struct inotify_kernel_event *kevent; - kevent = inotify_dev_get_event(dev); - remove_kevent(dev, kevent); - free_kevent(kevent); - } -} - -/* - * find_inode - resolve a user-given path to a specific inode - */ -static int 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; -} - -/* - * create_watch - creates a watch on the given device. - * - * Callers must hold dev->up_mutex. - */ -static int create_watch(struct inotify_device *dev, struct inode *inode, - u32 mask) -{ - struct inotify_user_watch *watch; - int ret; - - if (atomic_read(&dev->user->inotify_watches) >= - inotify_max_user_watches) - return -ENOSPC; - - watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL); - if (unlikely(!watch)) - return -ENOMEM; - - /* save a reference to device and bump the count to make it official */ - get_inotify_dev(dev); - watch->dev = dev; - - atomic_inc(&dev->user->inotify_watches); - - inotify_init_watch(&watch->wdata); - ret = inotify_add_watch(dev->ih, &watch->wdata, inode, mask); - if (ret < 0) - free_inotify_user_watch(&watch->wdata); - - return ret; -} - -/* Device Interface */ - -static unsigned int inotify_poll(struct file *file, poll_table *wait) -{ - struct inotify_device *dev = file->private_data; - int ret = 0; - - poll_wait(file, &dev->wq, wait); - mutex_lock(&dev->ev_mutex); - if (!list_empty(&dev->events)) - ret = POLLIN | POLLRDNORM; - mutex_unlock(&dev->ev_mutex); - - return ret; -} - -static ssize_t inotify_read(struct file *file, char __user *buf, - size_t count, loff_t *pos) -{ - size_t event_size = sizeof (struct inotify_event); - struct inotify_device *dev; - char __user *start; - int ret; - DEFINE_WAIT(wait); - - start = buf; - dev = file->private_data; - - while (1) { - - prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE); - - mutex_lock(&dev->ev_mutex); - if (!list_empty(&dev->events)) { - ret = 0; - break; - } - mutex_unlock(&dev->ev_mutex); - - if (file->f_flags & O_NONBLOCK) { - ret = -EAGAIN; - break; - } - - if (signal_pending(current)) { - ret = -EINTR; - break; - } - - schedule(); - } - - finish_wait(&dev->wq, &wait); - if (ret) - return ret; - - while (1) { - struct inotify_kernel_event *kevent; - - ret = buf - start; - if (list_empty(&dev->events)) - break; - - kevent = inotify_dev_get_event(dev); - if (event_size + kevent->event.len > count) { - if (ret == 0 && count > 0) { - /* - * could not get a single event because we - * didn't have enough buffer space. - */ - ret = -EINVAL; - } - break; - } - remove_kevent(dev, kevent); - - /* - * Must perform the copy_to_user outside the mutex in order - * to avoid a lock order reversal with mmap_sem. - */ - mutex_unlock(&dev->ev_mutex); - - if (copy_to_user(buf, &kevent->event, event_size)) { - ret = -EFAULT; - break; - } - buf += event_size; - count -= event_size; - - if (kevent->name) { - if (copy_to_user(buf, kevent->name, kevent->event.len)){ - ret = -EFAULT; - break; - } - buf += kevent->event.len; - count -= kevent->event.len; - } - - free_kevent(kevent); - - mutex_lock(&dev->ev_mutex); - } - mutex_unlock(&dev->ev_mutex); - - return ret; -} - -static int inotify_fasync(int fd, struct file *file, int on) -{ - struct inotify_device *dev = file->private_data; - - return fasync_helper(fd, file, on, &dev->fa) >= 0 ? 0 : -EIO; -} - -static int inotify_release(struct inode *ignored, struct file *file) -{ - struct inotify_device *dev = file->private_data; - - inotify_destroy(dev->ih); - - /* destroy all of the events on this device */ - mutex_lock(&dev->ev_mutex); - while (!list_empty(&dev->events)) - inotify_dev_event_dequeue(dev); - mutex_unlock(&dev->ev_mutex); - - /* free this device: the put matching the get in inotify_init() */ - put_inotify_dev(dev); - - return 0; -} - -static long inotify_ioctl(struct file *file, unsigned int cmd, - unsigned long arg) -{ - struct inotify_device *dev; - void __user *p; - int ret = -ENOTTY; - - dev = file->private_data; - p = (void __user *) arg; - - switch (cmd) { - case FIONREAD: - ret = put_user(dev->queue_size, (int __user *) p); - break; - } - - return ret; -} - -static const struct file_operations inotify_fops = { - .poll = inotify_poll, - .read = inotify_read, - .fasync = inotify_fasync, - .release = inotify_release, - .unlocked_ioctl = inotify_ioctl, - .compat_ioctl = inotify_ioctl, -}; - -static const struct inotify_operations inotify_user_ops = { - .handle_event = inotify_dev_queue_event, - .destroy_watch = free_inotify_user_watch, -}; - -asmlinkage long sys_inotify_init1(int flags) -{ - struct inotify_device *dev; - struct inotify_handle *ih; - struct user_struct *user; - struct file *filp; - int fd, 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; - - fd = get_unused_fd_flags(flags & O_CLOEXEC); - if (fd < 0) - return fd; - - filp = get_empty_filp(); - if (!filp) { - ret = -ENFILE; - goto out_put_fd; - } - - user = get_current_user(); - if (unlikely(atomic_read(&user->inotify_devs) >= - inotify_max_user_instances)) { - ret = -EMFILE; - goto out_free_uid; - } - - dev = kmalloc(sizeof(struct inotify_device), GFP_KERNEL); - if (unlikely(!dev)) { - ret = -ENOMEM; - goto out_free_uid; - } - - ih = inotify_init(&inotify_user_ops); - if (IS_ERR(ih)) { - ret = PTR_ERR(ih); - goto out_free_dev; - } - dev->ih = ih; - dev->fa = NULL; - - filp->f_op = &inotify_fops; - filp->f_path.mnt = mntget(inotify_mnt); - filp->f_path.dentry = dget(inotify_mnt->mnt_root); - filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping; - filp->f_mode = FMODE_READ; - filp->f_flags = O_RDONLY | (flags & O_NONBLOCK); - filp->private_data = dev; - - INIT_LIST_HEAD(&dev->events); - init_waitqueue_head(&dev->wq); - mutex_init(&dev->ev_mutex); - mutex_init(&dev->up_mutex); - dev->event_count = 0; - dev->queue_size = 0; - dev->max_events = inotify_max_queued_events; - dev->user = user; - atomic_set(&dev->count, 0); - - get_inotify_dev(dev); - atomic_inc(&user->inotify_devs); - fd_install(fd, filp); - - return fd; -out_free_dev: - kfree(dev); -out_free_uid: - free_uid(user); - put_filp(filp); -out_put_fd: - put_unused_fd(fd); - return ret; -} - -asmlinkage long sys_inotify_init(void) -{ - return sys_inotify_init1(0); -} - -asmlinkage long sys_inotify_add_watch(int fd, const char __user *pathname, u32 mask) -{ - struct inode *inode; - struct inotify_device *dev; - 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 = find_inode(pathname, &path, flags); - if (unlikely(ret)) - goto fput_and_out; - - /* inode held in place by reference to path; dev by fget on fd */ - inode = path.dentry->d_inode; - dev = filp->private_data; - - mutex_lock(&dev->up_mutex); - ret = inotify_find_update_watch(dev->ih, inode, mask); - if (ret == -ENOENT) - ret = create_watch(dev, inode, mask); - mutex_unlock(&dev->up_mutex); - - path_put(&path); -fput_and_out: - fput_light(filp, fput_needed); - return ret; -} - -asmlinkage long sys_inotify_rm_watch(int fd, u32 wd) -{ - struct file *filp; - struct inotify_device *dev; - int ret, fput_needed; - - 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 out; - } - - dev = filp->private_data; - - /* we free our watch data when we get IN_IGNORED */ - ret = inotify_rm_wd(dev->ih, wd); - -out: - fput_light(filp, fput_needed); - return ret; -} - -static int -inotify_get_sb(struct file_system_type *fs_type, int flags, - const char *dev_name, void *data, struct vfsmount *mnt) -{ - return get_sb_pseudo(fs_type, "inotify", NULL, - INOTIFYFS_SUPER_MAGIC, mnt); -} - -static struct file_system_type inotify_fs_type = { - .name = "inotifyfs", - .get_sb = inotify_get_sb, - .kill_sb = kill_anon_super, -}; - -/* - * inotify_user_setup - Our initialization function. Note that we cannnot 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) -{ - int ret; - - ret = register_filesystem(&inotify_fs_type); - if (unlikely(ret)) - panic("inotify: register_filesystem returned %d!\n", ret); - - inotify_mnt = kern_mount(&inotify_fs_type); - if (IS_ERR(inotify_mnt)) - panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt)); - - inotify_max_queued_events = 16384; - inotify_max_user_instances = 128; - inotify_max_user_watches = 8192; - - watch_cachep = kmem_cache_create("inotify_watch_cache", - sizeof(struct inotify_user_watch), - 0, SLAB_PANIC, NULL); - event_cachep = kmem_cache_create("inotify_event_cache", - sizeof(struct inotify_kernel_event), - 0, SLAB_PANIC, NULL); - - return 0; -} - -module_init(inotify_user_setup); |