// 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 <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;
/*
* Get an fsnotify notification event if one exists and is small
* enough to fit in "count". Return an error pointer if the count
* is not large enough.
*
* Called with the group->notification_lock held.
*/
static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
size_t count)
{
assert_spin_locked(&group->notification_lock);
pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
if (fsnotify_notify_queue_is_empty(group))
return NULL;
if (FAN_EVENT_METADATA_LEN > count)
return ERR_PTR(-EINVAL);
/* held the notification_lock the whole time, so this is the
* same event we peeked above */
return fsnotify_remove_first_event(group);
}
static int create_fd(struct fsnotify_group *group,
struct fanotify_event_info *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;
}
static int fill_event_metadata(struct fsnotify_group *group,
struct fanotify_event_metadata *metadata,
struct fsnotify_event *fsn_event,
struct file **file)
{
int ret = 0;
struct fanotify_event_info *event;
pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
group, metadata, fsn_event);
*file = NULL;
event = container_of(fsn_event, struct fanotify_event_info, 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 = fsn_event->mask & FAN_ALL_OUTGOING_EVENTS;
metadata->pid = pid_vnr(event->tgid);
if (unlikely(fsn_event->mask & FAN_Q_OVERFLOW))
metadata->fd = FAN_NOFD;
else {
metadata->fd = create_fd(group, event, file);
if (metadata->fd < 0)
ret = metadata->fd;
}
return ret;
}
static struct fanotify_perm_event_info *dequeue_event(
struct fsnotify_group *group, int fd)
{
struct fanotify_perm_event_info *event, *return_e = NULL;
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);
return_e = event;
break;
}
spin_unlock(&group->notification_lock);
pr_debug("%s: found return_re=%p\n", __func__, return_e);
return return_e;
}
static int process_access_response(struct fsnotify_group *group,
struct fanotify_response *response_struct