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linux/fs/notify/inotify/inotify_user.c
Aaron Goidel ac5656d8a4 fanotify, inotify, dnotify, security: add security hook for fs notifications 
As of now, setting watches on filesystem objects has, at most, applied a
check for read access to the inode, and in the case of fanotify, requires
CAP_SYS_ADMIN. No specific security hook or permission check has been
provided to control the setting of watches. Using any of inotify, dnotify,
or fanotify, it is possible to observe, not only write-like operations, but
even read access to a file. Modeling the watch as being merely a read from
the file is insufficient for the needs of SELinux. This is due to the fact
that read access should not necessarily imply access to information about
when another process reads from a file. Furthermore, fanotify watches grant
more power to an application in the form of permission events. While
notification events are solely, unidirectional (i.e. they only pass
information to the receiving application), permission events are blocking.
Permission events make a request to the receiving application which will
then reply with a decision as to whether or not that action may be
completed. This causes the issue of the watching application having the
ability to exercise control over the triggering process. Without drawing a
distinction within the permission check, the ability to read would imply
the greater ability to control an application. Additionally, mount and
superblock watches apply to all files within the same mount or superblock.
Read access to one file should not necessarily imply the ability to watch
all files accessed within a given mount or superblock.

In order to solve these issues, a new LSM hook is implemented and has been
placed within the system calls for marking filesystem objects with inotify,
fanotify, and dnotify watches. These calls to the hook are placed at the
point at which the target path has been resolved and are provided with the
path struct, the mask of requested notification events, and the type of
object on which the mark is being set (inode, superblock, or mount). The
mask and obj_type have already been translated into common FS_* values
shared by the entirety of the fs notification infrastructure. The path
struct is passed rather than just the inode so that the mount is available,
particularly for mount watches. This also allows for use of the hook by
pathname-based security modules. However, since the hook is intended for
use even by inode based security modules, it is not placed under the
CONFIG_SECURITY_PATH conditional. Otherwise, the inode-based security
modules would need to enable all of the path hooks, even though they do not
use any of them.

This only provides a hook at the point of setting a watch, and presumes
that permission to set a particular watch implies the ability to receive
all notification about that object which match the mask. This is all that
is required for SELinux. If other security modules require additional hooks
or infrastructure to control delivery of notification, these can be added
by them. It does not make sense for us to propose hooks for which we have
no implementation. The understanding that all notifications received by the
requesting application are all strictly of a type for which the application
has been granted permission shows that this implementation is sufficient in
its coverage.

Security modules wishing to provide complete control over fanotify must
also implement a security_file_open hook that validates that the access
requested by the watching application is authorized. Fanotify has the issue
that it returns a file descriptor with the file mode specified during
fanotify_init() to the watching process on event. This is already covered
by the LSM security_file_open hook if the security module implements
checking of the requested file mode there. Otherwise, a watching process
can obtain escalated access to a file for which it has not been authorized.

The selinux_path_notify hook implementation works by adding five new file
permissions: watch, watch_mount, watch_sb, watch_reads, and watch_with_perm
(descriptions about which will follow), and one new filesystem permission:
watch (which is applied to superblock checks). The hook then decides which
subset of these permissions must be held by the requesting application
based on the contents of the provided mask and the obj_type. The
selinux_file_open hook already checks the requested file mode and therefore
ensures that a watching process cannot escalate its access through
fanotify.

The watch, watch_mount, and watch_sb permissions are the baseline
permissions for setting a watch on an object and each are a requirement for
any watch to be set on a file, mount, or superblock respectively. It should
be noted that having either of the other two permissions (watch_reads and
watch_with_perm) does not imply the watch, watch_mount, or watch_sb
permission. Superblock watches further require the filesystem watch
permission to the superblock. As there is no labeled object in view for
mounts, there is no specific check for mount watches beyond watch_mount to
the inode. Such a check could be added in the future, if a suitable labeled
object existed representing the mount.

The watch_reads permission is required to receive notifications from
read-exclusive events on filesystem objects. These events include accessing
a file for the purpose of reading and closing a file which has been opened
read-only. This distinction has been drawn in order to provide a direct
indication in the policy for this otherwise not obvious capability. Read
access to a file should not necessarily imply the ability to observe read
events on a file.

Finally, watch_with_perm only applies to fanotify masks since it is the
only way to set a mask which allows for the blocking, permission event.
This permission is needed for any watch which is of this type. Though
fanotify requires CAP_SYS_ADMIN, this is insufficient as it gives implicit
trust to root, which we do not do, and does not support least privilege.

Signed-off-by: Aaron Goidel <acgoide@tycho.nsa.gov>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-08-12 17:45:39 -04:00

846 lines
21 KiB
C
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/*
* 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.
*
* Copyright (C) 2009 Eric Paris <Red Hat Inc>
* 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 <linux/file.h>
#include <linux/fs.h> /* struct inode */
#include <linux/fsnotify_backend.h>
#include <linux/idr.h>
#include <linux/init.h> /* fs_initcall */
#include <linux/inotify.h>
#include <linux/kernel.h> /* roundup() */
#include <linux/namei.h> /* LOOKUP_FOLLOW */
#include <linux/sched/signal.h>
#include <linux/slab.h> /* struct kmem_cache */
#include <linux/syscalls.h>
#include <linux/types.h>
#include <linux/anon_inodes.h>
#include <linux/uaccess.h>
#include <linux/poll.h>
#include <linux/wait.h>
#include <linux/memcontrol.h>
#include <linux/security.h>
#include "inotify.h"
#include "../fdinfo.h"
#include <asm/ioctls.h>
/* configurable via /proc/sys/fs/inotify/ */
static int inotify_max_queued_events __read_mostly;
struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
static int zero;
struct ctl_table inotify_table[] = {
{
.procname = "max_user_instances",
.data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES],
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
},
{
.procname = "max_user_watches",
.data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_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 __poll_t inotify_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 int round_event_name_len(struct fsnotify_event *fsn_event)
{
struct inotify_event_info *event;
event = INOTIFY_E(fsn_event);
if (!event->name_len)
return 0;
return roundup(event->name_len + 1, sizeof(struct inotify_event));
}
/*
* 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_lock 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_first_event(group);
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
event_size += round_event_name_len(event);
if (event_size > count)
return ERR_PTR(-EINVAL);
/* held the notification_lock the whole time, so this is the
* same event we peeked above */
fsnotify_remove_first_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 *fsn_event,
char __user *buf)
{
struct inotify_event inotify_event;
struct inotify_event_info *event;
size_t event_size = sizeof(struct inotify_event);
size_t name_len;
size_t pad_name_len;
pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
event = INOTIFY_E(fsn_event);
name_len = event->name_len;
/*
* round up name length so it is a multiple of event_size
* plus an extra byte for the terminating '\0'.
*/
pad_name_len = round_event_name_len(fsn_event);
inotify_event.len = pad_name_len;
inotify_event.mask = inotify_mask_to_arg(event->mask);
inotify_event.wd = event->wd;
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.
*/
if (pad_name_len) {
/* copy the path name */
if (copy_to_user(buf, event->name, name_len))
return -EFAULT;
buf += name_len;
/* fill userspace with 0's */
if (clear_user(buf, pad_name_len - name_len))
return -EFAULT;
event_size += pad_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_FUNC(wait, woken_wake_function);
start = buf;
group = file->private_data;
add_wait_queue(&group->notification_waitq, &wait);
while (1) {
spin_lock(&group->notification_lock);
kevent = get_one_event(group, count);
spin_unlock(&group->notification_lock);
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_destroy_event(group, 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;
wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
remove_wait_queue(&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);
/* 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 *fsn_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:
spin_lock(&group->notification_lock);
list_for_each_entry(fsn_event, &group->notification_list,
list) {
send_len += sizeof(struct inotify_event);
send_len += round_event_name_len(fsn_event);
}
spin_unlock(&group->notification_lock);
ret = put_user(send_len, (int __user *) p);
break;
#ifdef CONFIG_CHECKPOINT_RESTORE
case INOTIFY_IOC_SETNEXTWD:
ret = -EINVAL;
if (arg >= 1 && arg <= INT_MAX) {
struct inotify_group_private_data *data;
data = &group->inotify_data;
spin_lock(&data->idr_lock);
idr_set_cursor(&data->idr, (unsigned int)arg);
spin_unlock(&data->idr_lock);
ret = 0;
}
break;
#endif /* CONFIG_CHECKPOINT_RESTORE */
}
return ret;
}
static const struct file_operations inotify_fops = {
.show_fdinfo = inotify_show_fdinfo,
.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 int flags, __u64 mask)
{
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;
}
error = security_path_notify(path, mask,
FSNOTIFY_OBJ_TYPE_INODE);
if (error)
path_put(path);
return error;
}
static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
struct inotify_inode_mark *i_mark)
{
int ret;
idr_preload(GFP_KERNEL);
spin_lock(idr_lock);
ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT);
if (ret >= 0) {
/* we added the mark to the idr, take a reference */
i_mark->wd = ret;
fsnotify_get_mark(&i_mark->fsn_mark);
}
spin_unlock(idr_lock);
idr_preload_end();
return ret < 0 ? ret : 0;
}
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(refcount_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;
}
/*
* 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)
{
struct idr *idr = &group->inotify_data.idr;
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\n",
__func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
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\n",
__func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
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 "
"found_i_mark=%p found_i_mark->wd=%d "
"found_i_mark->group=%p\n", __func__, i_mark,
i_mark->wd, i_mark->fsn_mark.group, found_i_mark,
found_i_mark->wd, found_i_mark->fsn_mark.group);
goto out;
}
/*
* One ref for being in the idr
* one ref grabbed by inotify_idr_find
*/
if (unlikely(refcount_read(&i_mark->fsn_mark.refcnt) < 2)) {
printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n",
__func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
/* we can't really recover with bad ref cnting.. */
BUG();
}
idr_remove(idr, wd);
/* Removed from the idr, drop that ref. */
fsnotify_put_mark(&i_mark->fsn_mark);
out:
i_mark->wd = -1;
spin_unlock(idr_lock);
/* match the ref taken by inotify_idr_find_locked() */
if (found_i_mark)
fsnotify_put_mark(&found_i_mark->fsn_mark);
}
/*
* 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_iter_info iter_info = { };
fsnotify_iter_set_report_type_mark(&iter_info, FSNOTIFY_OBJ_TYPE_INODE,
fsn_mark);
/* Queue ignore event for the watch */
inotify_handle_event(group, NULL, FS_IN_IGNORED, NULL,
FSNOTIFY_EVENT_NONE, NULL, 0, &iter_info);
i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
/* remove this mark from the idr */
inotify_remove_from_idr(group, i_mark);
dec_inotify_watches(group->inotify_data.ucounts);
}
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 create = (arg & IN_MASK_CREATE);
int ret;
mask = inotify_arg_to_mask(arg);
fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
if (!fsn_mark)
return -ENOENT;
else if (create) {
ret = -EEXIST;
goto out;
}
i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
spin_lock(&fsn_mark->lock);
old_mask = fsn_mark->mask;
if (add)
fsn_mark->mask |= mask;
else
fsn_mark->mask = 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_mask(inode->i_fsnotify_marks);
}
/* return the wd */
ret = i_mark->wd;
out:
/* 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;
mask = inotify_arg_to_mask(arg);
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, group);
tmp_i_mark->fsn_mark.mask = mask;
tmp_i_mark->wd = -1;
ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark);
if (ret)
goto out_err;
/* increment the number of watches the user has */
if (!inc_inotify_watches(group->inotify_data.ucounts)) {
inotify_remove_from_idr(group, tmp_i_mark);
ret = -ENOSPC;
goto out_err;
}
/* we are on the idr, now get on the inode */
ret = fsnotify_add_inode_mark_locked(&tmp_i_mark->fsn_mark, inode, 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;
}
/* 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;
mutex_lock(&group->mark_mutex);
/* 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);
mutex_unlock(&group->mark_mutex);
return ret;
}
static struct fsnotify_group *inotify_new_group(unsigned int max_events)
{
struct fsnotify_group *group;
struct inotify_event_info *oevent;
group = fsnotify_alloc_group(&inotify_fsnotify_ops);
if (IS_ERR(group))
return group;
oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL);
if (unlikely(!oevent)) {
fsnotify_destroy_group(group);
return ERR_PTR(-ENOMEM);
}
group->overflow_event = &oevent->fse;
fsnotify_init_event(group->overflow_event, NULL);
oevent->mask = FS_Q_OVERFLOW;
oevent->wd = -1;
oevent->sync_cookie = 0;
oevent->name_len = 0;
group->max_events = max_events;
group->memcg = get_mem_cgroup_from_mm(current->mm);
spin_lock_init(&group->inotify_data.idr_lock);
idr_init(&group->inotify_data.idr);
group->inotify_data.ucounts = inc_ucount(current_user_ns(),
current_euid(),
UCOUNT_INOTIFY_INSTANCES);
if (!group->inotify_data.ucounts) {
fsnotify_destroy_group(group);
return ERR_PTR(-EMFILE);
}
return group;
}
/* inotify syscalls */
static int do_inotify_init(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_DEFINE1(inotify_init1, int, flags)
{
return do_inotify_init(flags);
}
SYSCALL_DEFINE0(inotify_init)
{
return do_inotify_init(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 fd f;
int ret;
unsigned flags = 0;
/*
* We share a lot of code with fs/dnotify. We also share
* the bit layout between inotify's IN_* and the fsnotify
* FS_*. This check ensures that only the inotify IN_*
* bits get passed in and set in watches/events.
*/
if (unlikely(mask & ~ALL_INOTIFY_BITS))
return -EINVAL;
/*
* Require at least one valid bit set in the mask.
* Without _something_ set, we would have no events to
* watch for.
*/
if (unlikely(!(mask & ALL_INOTIFY_BITS)))
return -EINVAL;
f = fdget(fd);
if (unlikely(!f.file))
return -EBADF;
/* IN_MASK_ADD and IN_MASK_CREATE don't make sense together */
if (unlikely((mask & IN_MASK_ADD) && (mask & IN_MASK_CREATE))) {
ret = -EINVAL;
goto fput_and_out;
}
/* verify that this is indeed an inotify instance */
if (unlikely(f.file->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,
(mask & IN_ALL_EVENTS));
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 = f.file->private_data;
/* create/update an inode mark */
ret = inotify_update_watch(group, inode, mask);
path_put(&path);
fput_and_out:
fdput(f);
return ret;
}
SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
{
struct fsnotify_group *group;
struct inotify_inode_mark *i_mark;
struct fd f;
int ret = 0;
f = fdget(fd);
if (unlikely(!f.file))
return -EBADF;
/* verify that this is indeed an inotify instance */
ret = -EINVAL;
if (unlikely(f.file->f_op != &inotify_fops))
goto out;
group = f.file->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:
fdput(f);
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);
BUILD_BUG_ON(HWEIGHT32(ALL_INOTIFY_BITS) != 22);
inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark,
SLAB_PANIC|SLAB_ACCOUNT);
inotify_max_queued_events = 16384;
init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128;
init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = 8192;
return 0;
}
fs_initcall(inotify_user_setup);
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