// 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>
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#include <linux/init.h>
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#include <linux/mount.h>
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#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"
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#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_fid_event_cachep __read_mostly;
|
struct kmem_cache *fanotify_path_event_cachep __read_mostly;
|
struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
|
|
#define FANOTIFY_EVENT_ALIGN 4
|
#define FANOTIFY_INFO_HDR_LEN \
|
(sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle))
|
|
static int fanotify_fid_info_len(int fh_len, int name_len)
|
{
|
int info_len = fh_len;
|
|
if (name_len)
|
info_len += name_len + 1;
|
|
return roundup(FANOTIFY_INFO_HDR_LEN + info_len, FANOTIFY_EVENT_ALIGN);
|
}
|
|
static int fanotify_event_info_len(unsigned int fid_mode,
|
struct fanotify_event *event)
|
{
|
struct fanotify_info *info = fanotify_event_info(event);
|
int dir_fh_len = fanotify_event_dir_fh_len(event);
|
int fh_len = fanotify_event_object_fh_len(event);
|
int info_len = 0;
|
int dot_len = 0;
|
|
if (dir_fh_len) {
|
info_len += fanotify_fid_info_len(dir_fh_len, info->name_len);
|
} else if ((fid_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) {
|
/*
|
* With group flag FAN_REPORT_NAME, if name was not recorded in
|
* event on a directory, we will report the name ".".
|
*/
|
dot_len = 1;
|
}
|
|
if (fh_len)
|
info_len += fanotify_fid_info_len(fh_len, dot_len);
|
|
return info_len;
|
}
|
|
/*
|
* Get an fanotify 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 fanotify_event *get_one_event(struct fsnotify_group *group,
|
size_t count)
|
{
|
size_t event_size = FAN_EVENT_METADATA_LEN;
|
struct fanotify_event *event = NULL;
|
unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
|
|
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 (fid_mode) {
|
event_size += fanotify_event_info_len(fid_mode,
|
FANOTIFY_E(fsnotify_peek_first_event(group)));
|
}
|
|
if (event_size > count) {
|
event = ERR_PTR(-EINVAL);
|
goto out;
|
}
|
event = FANOTIFY_E(fsnotify_remove_first_event(group));
|
if (fanotify_is_perm_event(event->mask))
|
FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED;
|
out:
|
spin_unlock(&group->notification_lock);
|
return event;
|
}
|
|
static int create_fd(struct fsnotify_group *group, struct path *path,
|
struct file **file)
|
{
|
int client_fd;
|
struct file *new_file;
|
|
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.
|
*/
|
new_file = dentry_open(path,
|
group->fanotify_data.f_flags | FMODE_NONOTIFY,
|
current_cred());
|
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_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
|
int info_type, const char *name, size_t name_len,
|
char __user *buf, size_t count)
|
{
|
struct fanotify_event_info_fid info = { };
|
struct file_handle handle = { };
|
unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf;
|
size_t fh_len = fh ? fh->len : 0;
|
size_t info_len = fanotify_fid_info_len(fh_len, name_len);
|
size_t len = info_len;
|
|
pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",
|
__func__, fh_len, name_len, info_len, count);
|
|
if (!fh_len)
|
return 0;
|
|
if (WARN_ON_ONCE(len < sizeof(info) || len > count))
|
return -EFAULT;
|
|
/*
|
* Copy event info fid header followed by variable sized file handle
|
* and optionally followed by variable sized filename.
|
*/
|
switch (info_type) {
|
case FAN_EVENT_INFO_TYPE_FID:
|
case FAN_EVENT_INFO_TYPE_DFID:
|
if (WARN_ON_ONCE(name_len))
|
return -EFAULT;
|
break;
|
case FAN_EVENT_INFO_TYPE_DFID_NAME:
|
if (WARN_ON_ONCE(!name || !name_len))
|
return -EFAULT;
|
break;
|
default:
|
return -EFAULT;
|
}
|
|
info.hdr.info_type = info_type;
|
info.hdr.len = len;
|
info.fsid = *fsid;
|
if (copy_to_user(buf, &info, sizeof(info)))
|
return -EFAULT;
|
|
buf += sizeof(info);
|
len -= sizeof(info);
|
if (WARN_ON_ONCE(len < sizeof(handle)))
|
return -EFAULT;
|
|
handle.handle_type = fh->type;
|
handle.handle_bytes = fh_len;
|
if (copy_to_user(buf, &handle, sizeof(handle)))
|
return -EFAULT;
|
|
buf += sizeof(handle);
|
len -= sizeof(handle);
|
if (WARN_ON_ONCE(len < fh_len))
|
return -EFAULT;
|
|
/*
|
* For an inline fh and inline file name, copy through stack to exclude
|
* the copy from usercopy hardening protections.
|
*/
|
fh_buf = fanotify_fh_buf(fh);
|
if (fh_len <= FANOTIFY_INLINE_FH_LEN) {
|
memcpy(bounce, fh_buf, fh_len);
|
fh_buf = bounce;
|
}
|
if (copy_to_user(buf, fh_buf, fh_len))
|
return -EFAULT;
|
|
buf += fh_len;
|
len -= fh_len;
|
|
if (name_len) {
|
/* Copy the filename with terminating null */
|
name_len++;
|
if (WARN_ON_ONCE(len < name_len))
|
return -EFAULT;
|
|
if (copy_to_user(buf, name, name_len))
|
return -EFAULT;
|
|
buf += name_len;
|
len -= name_len;
|
}
|
|
/* Pad with 0's */
|
WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN);
|
if (len > 0 && clear_user(buf, len))
|
return -EFAULT;
|
|
return info_len;
|
}
|
|
static ssize_t copy_event_to_user(struct fsnotify_group *group,
|
struct fanotify_event *event,
|
char __user *buf, size_t count)
|
{
|
struct fanotify_event_metadata metadata;
|
struct path *path = fanotify_event_path(event);
|
struct fanotify_info *info = fanotify_event_info(event);
|
unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
|
struct file *f = NULL;
|
int ret, fd = FAN_NOFD;
|
int info_type = 0;
|
|
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
|
|
metadata.event_len = FAN_EVENT_METADATA_LEN +
|
fanotify_event_info_len(fid_mode, event);
|
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 (path && path->mnt && path->dentry) {
|
fd = create_fd(group, path, &f);
|
if (fd < 0)
|
return fd;
|
}
|
metadata.fd = fd;
|
|
ret = -EFAULT;
|
/*
|
* Sanity check copy size in case get_one_event() and
|
* 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;
|
|
buf += FAN_EVENT_METADATA_LEN;
|
count -= FAN_EVENT_METADATA_LEN;
|
|
if (fanotify_is_perm_event(event->mask))
|
FANOTIFY_PERM(event)->fd = fd;
|
|
/* Event info records order is: dir fid + name, child fid */
|
if (fanotify_event_dir_fh_len(event)) {
|
info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
|
FAN_EVENT_INFO_TYPE_DFID;
|
ret = copy_info_to_user(fanotify_event_fsid(event),
|
fanotify_info_dir_fh(info),
|
info_type, fanotify_info_name(info),
|
info->name_len, buf, count);
|
if (ret < 0)
|
goto out_close_fd;
|
|
buf += ret;
|
count -= ret;
|
}
|
|
if (fanotify_event_object_fh_len(event)) {
|
const char *dot = NULL;
|
int dot_len = 0;
|
|
if (fid_mode == FAN_REPORT_FID || info_type) {
|
/*
|
* With only group flag FAN_REPORT_FID only type FID is
|
* reported. Second info record type is always FID.
|
*/
|
info_type = FAN_EVENT_INFO_TYPE_FID;
|
} else if ((fid_mode & FAN_REPORT_NAME) &&
|
(event->mask & FAN_ONDIR)) {
|
/*
|
* With group flag FAN_REPORT_NAME, if name was not
|
* recorded in an event on a directory, report the
|
* name "." with info type DFID_NAME.
|
*/
|
info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
|
dot = ".";
|
dot_len = 1;
|
} else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
|
(event->mask & FAN_ONDIR)) {
|
/*
|
* With group flag FAN_REPORT_DIR_FID, a single info
|
* record has type DFID for directory entry modification
|
* event and for event on a directory.
|
*/
|
info_type = FAN_EVENT_INFO_TYPE_DFID;
|
} else {
|
/*
|
* With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
|
* a single info record has type FID for event on a
|
* non-directory, when there is no directory to report.
|
* For example, on FAN_DELETE_SELF event.
|
*/
|
info_type = FAN_EVENT_INFO_TYPE_FID;
|
}
|
|
ret = copy_info_to_user(fanotify_event_fsid(event),
|
fanotify_event_object_fh(event),
|
info_type, dot, dot_len, buf, count);
|
if (ret < 0)
|
goto out_close_fd;
|
|
buf += ret;
|
count -= ret;
|
}
|
|
if (f)
|
fd_install(fd, f);
|
|
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 fanotify_event *event;
|
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) {
|
/*
|
* User can supply arbitrarily large buffer. Avoid softlockups
|
* in case there are lots of available events.
|
*/
|
cond_resched();
|
event = get_one_event(group, count);
|
if (IS_ERR(event)) {
|
ret = PTR_ERR(event);
|
break;
|
}
|
|
if (!event) {
|
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, event, 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(event->mask)) {
|
fsnotify_destroy_event(group, &event->fse);
|
} else {
|
if (ret <= 0) {
|
spin_lock(&group->notification_lock);
|
finish_permission_event(group,
|
FANOTIFY_PERM(event), FAN_DENY);
|
wake_up(&group->fanotify_data.access_waitq);
|
} else {
|
spin_lock(&group->notification_lock);
|
list_add_tail(&event->fse.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))
|
return -EINVAL;
|
|
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;
|
|
/*
|
* 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)) {
|
struct fanotify_perm_event *event;
|
|
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)) {
|
struct fanotify_event *event;
|
|
event = FANOTIFY_E(fsnotify_remove_first_event(group));
|
if (!(event->mask & FANOTIFY_PERM_EVENTS)) {
|
spin_unlock(&group->notification_lock);
|
fsnotify_destroy_event(group, &event->fse);
|
} else {
|
finish_permission_event(group, FANOTIFY_PERM(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 = compat_ptr_ioctl,
|
.llseek = noop_llseek,
|
};
|
|
static int fanotify_find_path(int dfd, const char __user *filename,
|
struct path *path, unsigned int flags, __u64 mask,
|
unsigned int obj_type)
|
{
|
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);
|
goto out;
|
}
|
|
ret = security_path_notify(path, mask, obj_type);
|
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,
|
__u32 umask, int *destroy)
|
{
|
__u32 oldmask = 0;
|
|
/* umask bits cannot be removed by user */
|
mask &= ~umask;
|
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;
|
}
|
/*
|
* We need to keep the mark around even if remaining mask cannot
|
* result in any events (e.g. mask == FAN_ONDIR) to support incremenal
|
* changes to the mask.
|
* Destroy mark when only umask bits remain.
|
*/
|
*destroy = !((fsn_mark->mask | fsn_mark->ignored_mask) & ~umask);
|
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, __u32 umask)
|
{
|
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,
|
umask, &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, __u32 umask)
|
{
|
return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks,
|
mask, flags, umask);
|
}
|
|
static int fanotify_remove_sb_mark(struct fsnotify_group *group,
|
struct super_block *sb, __u32 mask,
|
unsigned int flags, __u32 umask)
|
{
|
return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask,
|
flags, umask);
|
}
|
|
static int fanotify_remove_inode_mark(struct fsnotify_group *group,
|
struct inode *inode, __u32 mask,
|
unsigned int flags, __u32 umask)
|
{
|
return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask,
|
flags, umask);
|
}
|
|
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);
|
}
|
|
static struct fsnotify_event *fanotify_alloc_overflow_event(void)
|
{
|
struct fanotify_event *oevent;
|
|
oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT);
|
if (!oevent)
|
return NULL;
|
|
fanotify_init_event(oevent, 0, FS_Q_OVERFLOW);
|
oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW;
|
|
return &oevent->fse;
|
}
|
|
/* 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;
|
unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
|
unsigned int class = flags & FANOTIFY_CLASS_BITS;
|
|
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 (fid_mode && class != FAN_CLASS_NOTIF)
|
return -EINVAL;
|
|
/*
|
* Child name is reported with parent fid so requires dir fid.
|
* We can report both child fid and dir fid with or without name.
|
*/
|
if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID))
|
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);
|
|
group->overflow_event = fanotify_alloc_overflow_event();
|
if (unlikely(!group->overflow_event)) {
|
fd = -ENOMEM;
|
goto out_destroy_group;
|
}
|
|
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 (class) {
|
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 fanotify_events_supported(struct path *path, __u64 mask)
|
{
|
/*
|
* Some filesystems such as 'proc' acquire unusual locks when opening
|
* files. For them fanotify permission events have high chances of
|
* deadlocking the system - open done when reporting fanotify event
|
* blocks on this "unusual" lock while another process holding the lock
|
* waits for fanotify permission event to be answered. Just disallow
|
* permission events for such filesystems.
|
*/
|
if (mask & FANOTIFY_PERM_EVENTS &&
|
path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM)
|
return -EINVAL;
|
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;
|
bool ignored = flags & FAN_MARK_IGNORED_MASK;
|
unsigned int obj_type, fid_mode;
|
u32 umask = 0;
|
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:
|
obj_type = FSNOTIFY_OBJ_TYPE_INODE;
|
break;
|
case FAN_MARK_MOUNT:
|
obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT;
|
break;
|
case FAN_MARK_FILESYSTEM:
|
obj_type = FSNOTIFY_OBJ_TYPE_SB;
|
break;
|
default:
|
return -EINVAL;
|
}
|
|
switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
|
case FAN_MARK_ADD:
|
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;
|
|
/* Event flags (ONDIR, ON_CHILD) are meaningless in ignored mask */
|
if (ignored)
|
mask &= ~FANOTIFY_EVENT_FLAGS;
|
|
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.
|
*/
|
fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
|
if (mask & FANOTIFY_INODE_EVENTS &&
|
(!fid_mode || 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,
|
(mask & ALL_FSNOTIFY_EVENTS), obj_type);
|
if (ret)
|
goto fput_and_out;
|
|
if (flags & FAN_MARK_ADD) {
|
ret = fanotify_events_supported(&path, mask);
|
if (ret)
|
goto path_put_and_out;
|
}
|
|
if (fid_mode) {
|
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;
|
|
/* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */
|
if (mnt || !S_ISDIR(inode->i_mode)) {
|
mask &= ~FAN_EVENT_ON_CHILD;
|
umask = FAN_EVENT_ON_CHILD;
|
/*
|
* If group needs to report parent fid, register for getting
|
* events with parent/name info for non-directory.
|
*/
|
if ((fid_mode & FAN_REPORT_DIR_FID) &&
|
(flags & FAN_MARK_ADD) && !ignored)
|
mask |= FAN_EVENT_ON_CHILD;
|
}
|
|
/* 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, umask);
|
else if (mark_type == FAN_MARK_FILESYSTEM)
|
ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask,
|
flags, umask);
|
else
|
ret = fanotify_remove_inode_mark(group, inode, mask,
|
flags, umask);
|
break;
|
default:
|
ret = -EINVAL;
|
}
|
|
path_put_and_out:
|
path_put(&path);
|
fput_and_out:
|
fdput(f);
|
return ret;
|
}
|
|
#ifndef CONFIG_ARCH_SPLIT_ARG64
|
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);
|
}
|
#endif
|
|
#if defined(CONFIG_ARCH_SPLIT_ARG64) || defined(CONFIG_COMPAT)
|
SYSCALL32_DEFINE6(fanotify_mark,
|
int, fanotify_fd, unsigned int, flags,
|
SC_ARG64(mask), int, dfd,
|
const char __user *, pathname)
|
{
|
return do_fanotify_mark(fanotify_fd, flags, SC_VAL64(__u64, mask),
|
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) != 10);
|
BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);
|
|
fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
|
SLAB_PANIC|SLAB_ACCOUNT);
|
fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event,
|
SLAB_PANIC);
|
fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_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);
|
