linux_dsm_epyc7002/fs/notify/fanotify/fanotify_user.c
Jan Kara fabf7f29b3 fanotify: Use interruptible wait when waiting for permission events
When waiting for response to fanotify permission events, we currently
use uninterruptible waits. That makes code simple however it can cause
lots of processes to end up in uninterruptible sleep with hard reboot
being the only alternative in case fanotify listener process stops
responding (e.g. due to a bug in its implementation). Uninterruptible
sleep also makes system hibernation fail if the listener gets frozen
before the process generating fanotify permission event.

Fix these problems by using interruptible sleep for waiting for response
to fanotify event. This is slightly tricky though - we have to
detect when the event got already reported to userspace as in that
case we must not free the event. Instead we push the responsibility for
freeing the event to the process that will write response to the
event.

Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2019-02-18 12:41:16 +01:00

1104 lines
28 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/fanotify.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/anon_inodes.h>
#include <linux/fsnotify_backend.h>
#include <linux/init.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/poll.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/compat.h>
#include <linux/sched/signal.h>
#include <linux/memcontrol.h>
#include <linux/statfs.h>
#include <linux/exportfs.h>
#include <asm/ioctls.h>
#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_event_cachep __read_mostly;
struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
#define FANOTIFY_EVENT_ALIGN 4
static int fanotify_event_info_len(struct fanotify_event *event)
{
if (!fanotify_event_has_fid(event))
return 0;
return roundup(sizeof(struct fanotify_event_info_fid) +
sizeof(struct file_handle) + event->fh_len,
FANOTIFY_EVENT_ALIGN);
}
/*
* 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. When permission event is dequeued, its state is
* updated accordingly.
*/
static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
size_t count)
{
size_t event_size = FAN_EVENT_METADATA_LEN;
struct fsnotify_event *fsn_event = NULL;
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 (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
event_size += fanotify_event_info_len(
FANOTIFY_E(fsnotify_peek_first_event(group)));
}
if (event_size > count) {
fsn_event = ERR_PTR(-EINVAL);
goto out;
}
fsn_event = fsnotify_remove_first_event(group);
if (fanotify_is_perm_event(FANOTIFY_E(fsn_event)->mask))
FANOTIFY_PE(fsn_event)->state = FAN_EVENT_REPORTED;
out:
spin_unlock(&group->notification_lock);
return fsn_event;
}
static int create_fd(struct fsnotify_group *group,
struct fanotify_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_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.
*/
/* 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;
}
/*
* 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_fid_to_user(struct fanotify_event *event, char __user *buf)
{
struct fanotify_event_info_fid info = { };
struct file_handle handle = { };
size_t fh_len = event->fh_len;
size_t len = fanotify_event_info_len(event);
if (!len)
return 0;
if (WARN_ON_ONCE(len < sizeof(info) + sizeof(handle) + fh_len))
return -EFAULT;
/* Copy event info fid header followed by vaiable sized file handle */
info.hdr.info_type = FAN_EVENT_INFO_TYPE_FID;
info.hdr.len = len;
info.fsid = event->fid.fsid;
if (copy_to_user(buf, &info, sizeof(info)))
return -EFAULT;
buf += sizeof(info);
len -= sizeof(info);
handle.handle_type = event->fh_type;
handle.handle_bytes = fh_len;
if (copy_to_user(buf, &handle, sizeof(handle)))
return -EFAULT;
buf += sizeof(handle);
len -= sizeof(handle);
if (copy_to_user(buf, fanotify_event_fh(event), fh_len))
return -EFAULT;
/* Pad with 0's */
buf += fh_len;
len -= fh_len;
WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN);
if (len > 0 && clear_user(buf, len))
return -EFAULT;
return 0;
}
static ssize_t copy_event_to_user(struct fsnotify_group *group,
struct fsnotify_event *fsn_event,
char __user *buf, size_t count)
{
struct fanotify_event_metadata metadata;
struct fanotify_event *event;
struct file *f = NULL;
int ret, fd = FAN_NOFD;
pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
event = container_of(fsn_event, struct fanotify_event, fse);
metadata.event_len = FAN_EVENT_METADATA_LEN;
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 (fanotify_event_has_path(event)) {
fd = create_fd(group, event, &f);
if (fd < 0)
return fd;
} else if (fanotify_event_has_fid(event)) {
metadata.event_len += fanotify_event_info_len(event);
}
metadata.fd = fd;
ret = -EFAULT;
/*
* Sanity check copy size in case get_one_event() and
* fill_event_metadata() 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;
if (fanotify_is_perm_event(event->mask))
FANOTIFY_PE(fsn_event)->fd = fd;
if (fanotify_event_has_path(event)) {
fd_install(fd, f);
} else if (fanotify_event_has_fid(event)) {
ret = copy_fid_to_user(event, buf + FAN_EVENT_METADATA_LEN);
if (ret < 0)
return 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 fsnotify_event *kevent;
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) {
kevent = get_one_event(group, count);
if (IS_ERR(kevent)) {
ret = PTR_ERR(kevent);
break;
}
if (!kevent) {
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, kevent, 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(FANOTIFY_E(kevent)->mask)) {
fsnotify_destroy_event(group, kevent);
} else {
if (ret <= 0) {
spin_lock(&group->notification_lock);
finish_permission_event(group,
FANOTIFY_PE(kevent), FAN_DENY);
wake_up(&group->fanotify_data.access_waitq);
} else {
spin_lock(&group->notification_lock);
list_add_tail(&kevent->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))
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;
struct fanotify_perm_event *event;
struct fsnotify_event *fsn_event;
/*
* 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)) {
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)) {
fsn_event = fsnotify_remove_first_event(group);
if (!(FANOTIFY_E(fsn_event)->mask & FANOTIFY_PERM_EVENTS)) {
spin_unlock(&group->notification_lock);
fsnotify_destroy_event(group, fsn_event);
} else {
finish_permission_event(group, FANOTIFY_PE(fsn_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 = fanotify_ioctl,
.llseek = noop_llseek,
};
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 = 0;
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;
}
*destroy = !(fsn_mark->mask | fsn_mark->ignored_mask);
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)
{
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,
&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)
{
return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks,
mask, flags);
}
static int fanotify_remove_sb_mark(struct fsnotify_group *group,
struct super_block *sb, __u32 mask,
unsigned int flags)
{
return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, flags);
}
static int fanotify_remove_inode_mark(struct fsnotify_group *group,
struct inode *inode, __u32 mask,
unsigned int flags)
{
return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask,
flags);
}
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);
}
/* 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;
struct fanotify_event *oevent;
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 ((flags & FAN_REPORT_FID) &&
(flags & FANOTIFY_CLASS_BITS) != FAN_CLASS_NOTIF)
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);
oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL,
FSNOTIFY_EVENT_NONE, NULL);
if (unlikely(!oevent)) {
fd = -ENOMEM;
goto out_destroy_group;
}
group->overflow_event = &oevent->fse;
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 (flags & FANOTIFY_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;
}
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 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;
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:
case FAN_MARK_MOUNT:
case FAN_MARK_FILESYSTEM:
break;
default:
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;
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;
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.
*/
if (mask & FANOTIFY_INODE_EVENTS &&
(!FAN_GROUP_FLAG(group, FAN_REPORT_FID) ||
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);
if (ret)
goto fput_and_out;
if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
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;
/* 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);
else if (mark_type == FAN_MARK_FILESYSTEM)
ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask,
flags);
else
ret = fanotify_remove_inode_mark(group, inode, mask,
flags);
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) != 8);
BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);
fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
SLAB_PANIC|SLAB_ACCOUNT);
fanotify_event_cachep = KMEM_CACHE(fanotify_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);