tqcq/kernel
1
0
Fork 0
Code Issues Pull Requests Actions Projects Releases Wiki Activity
e5480701d3
kernel/fs/notify/fanotify/fanotify_user.c
tqcq e5480701d3 init repo.
2024-07-22 17:22:30 +08:00

1896 lines
50 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0
#include <linux/fanotify.h>
#include <linux/fcntl.h>
#include <linux/fdtable.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_OLD_DEFAULT_MAX_MARKS 8192
#define FANOTIFY_DEFAULT_MAX_GROUPS 128
#define FANOTIFY_DEFAULT_FEE_POOL_SIZE 32
/*
* Legacy fanotify marks limits (8192) is per group and we introduced a tunable
* limit of marks per user, similar to inotify. Effectively, the legacy limit
* of fanotify marks per user is <max marks per group> * <max groups per user>.
* This default limit (1M) also happens to match the increased limit of inotify
* max_user_watches since v5.10.
*/
#define FANOTIFY_DEFAULT_MAX_USER_MARKS \
(FANOTIFY_OLD_DEFAULT_MAX_MARKS * FANOTIFY_DEFAULT_MAX_GROUPS)
/*
* Most of the memory cost of adding an inode mark is pinning the marked inode.
* The size of the filesystem inode struct is not uniform across filesystems,
* so double the size of a VFS inode is used as a conservative approximation.
*/
#define INODE_MARK_COST (2 * sizeof(struct inode))
/* configurable via /proc/sys/fs/fanotify/ */
static int fanotify_max_queued_events __read_mostly;
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
static long ft_zero = 0;
static long ft_int_max = INT_MAX;
struct ctl_table fanotify_table[] = {
{
.procname = "max_user_groups",
.data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS],
.maxlen = sizeof(long),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
.extra1 = &ft_zero,
.extra2 = &ft_int_max,
},
{
.procname = "max_user_marks",
.data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS],
.maxlen = sizeof(long),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
.extra1 = &ft_zero,
.extra2 = &ft_int_max,
},
{
.procname = "max_queued_events",
.data = &fanotify_max_queued_events,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO
},
{ }
};
#endif /* CONFIG_SYSCTL */
/*
* 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_FID_INFO_HDR_LEN \
(sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle))
#define FANOTIFY_PIDFD_INFO_HDR_LEN \
sizeof(struct fanotify_event_info_pidfd)
#define FANOTIFY_ERROR_INFO_LEN \
(sizeof(struct fanotify_event_info_error))
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_FID_INFO_HDR_LEN + info_len,
FANOTIFY_EVENT_ALIGN);
}
/* FAN_RENAME may have one or two dir+name info records */
static int fanotify_dir_name_info_len(struct fanotify_event *event)
{
struct fanotify_info *info = fanotify_event_info(event);
int dir_fh_len = fanotify_event_dir_fh_len(event);
int dir2_fh_len = fanotify_event_dir2_fh_len(event);
int info_len = 0;
if (dir_fh_len)
info_len += fanotify_fid_info_len(dir_fh_len,
info->name_len);
if (dir2_fh_len)
info_len += fanotify_fid_info_len(dir2_fh_len,
info->name2_len);
return info_len;
}
static size_t fanotify_event_len(unsigned int info_mode,
struct fanotify_event *event)
{
size_t event_len = FAN_EVENT_METADATA_LEN;
struct fanotify_info *info;
int fh_len;
int dot_len = 0;
if (!info_mode)
return event_len;
if (fanotify_is_error_event(event->mask))
event_len += FANOTIFY_ERROR_INFO_LEN;
info = fanotify_event_info(event);
if (fanotify_event_has_any_dir_fh(event)) {
event_len += fanotify_dir_name_info_len(event);
} else if ((info_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 (info_mode & FAN_REPORT_PIDFD)
event_len += FANOTIFY_PIDFD_INFO_HDR_LEN;
if (fanotify_event_has_object_fh(event)) {
fh_len = fanotify_event_object_fh_len(event);
event_len += fanotify_fid_info_len(fh_len, dot_len);
}
return event_len;
}
/*
* Remove an hashed event from merge hash table.
*/
static void fanotify_unhash_event(struct fsnotify_group *group,
struct fanotify_event *event)
{
assert_spin_locked(&group->notification_lock);
pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
group, event, fanotify_event_hash_bucket(group, event));
if (WARN_ON_ONCE(hlist_unhashed(&event->merge_list)))
return;
hlist_del_init(&event->merge_list);
}
/*
* 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;
struct fanotify_event *event = NULL;
struct fsnotify_event *fsn_event;
unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
spin_lock(&group->notification_lock);
fsn_event = fsnotify_peek_first_event(group);
if (!fsn_event)
goto out;
event = FANOTIFY_E(fsn_event);
event_size = fanotify_event_len(info_mode, event);
if (event_size > count) {
event = ERR_PTR(-EINVAL);
goto out;
}
/*
* Held the notification_lock the whole time, so this is the
* same event we peeked above.
*/
fsnotify_remove_first_event(group);
if (fanotify_is_perm_event(event->mask))
FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED;
if (fanotify_is_hashed_event(event->mask))
fanotify_unhash_event(group, event);
out:
spin_unlock(&group->notification_lock);
return event;
}
static int create_fd(struct fsnotify_group *group, const 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 size_t copy_error_info_to_user(struct fanotify_event *event,
char __user *buf, int count)
{
struct fanotify_event_info_error info = { };
struct fanotify_error_event *fee = FANOTIFY_EE(event);
info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
info.hdr.len = FANOTIFY_ERROR_INFO_LEN;
if (WARN_ON(count < info.hdr.len))
return -EFAULT;
info.error = fee->error;
info.error_count = fee->err_count;
if (copy_to_user(buf, &info, sizeof(info)))
return -EFAULT;
return info.hdr.len;
}
static int copy_fid_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 (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:
case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME:
case FAN_EVENT_INFO_TYPE_NEW_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;
/* Mangle handle_type for bad file_handle */
if (!fh_len)
handle.handle_type = FILEID_INVALID;
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 int copy_pidfd_info_to_user(int pidfd,
char __user *buf,
size_t count)
{
struct fanotify_event_info_pidfd info = { };
size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN;
if (WARN_ON_ONCE(info_len > count))
return -EFAULT;
info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD;
info.hdr.len = info_len;
info.pidfd = pidfd;
if (copy_to_user(buf, &info, info_len))
return -EFAULT;
return info_len;
}
static int copy_info_records_to_user(struct fanotify_event *event,
struct fanotify_info *info,
unsigned int info_mode, int pidfd,
char __user *buf, size_t count)
{
int ret, total_bytes = 0, info_type = 0;
unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS;
unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
/*
* Event info records order is as follows:
* 1. dir fid + name
* 2. (optional) new dir fid + new name
* 3. (optional) child fid
*/
if (fanotify_event_has_dir_fh(event)) {
info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
FAN_EVENT_INFO_TYPE_DFID;
/* FAN_RENAME uses special info types */
if (event->mask & FAN_RENAME)
info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME;
ret = copy_fid_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)
return ret;
buf += ret;
count -= ret;
total_bytes += ret;
}
/* New dir fid+name may be reported in addition to old dir fid+name */
if (fanotify_event_has_dir2_fh(event)) {
info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME;
ret = copy_fid_info_to_user(fanotify_event_fsid(event),
fanotify_info_dir2_fh(info),
info_type,
fanotify_info_name2(info),
info->name2_len, buf, count);
if (ret < 0)
return ret;
buf += ret;
count -= ret;
total_bytes += ret;
}
if (fanotify_event_has_object_fh(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_fid_info_to_user(fanotify_event_fsid(event),
fanotify_event_object_fh(event),
info_type, dot, dot_len,
buf, count);
if (ret < 0)
return ret;
buf += ret;
count -= ret;
total_bytes += ret;
}
if (pidfd_mode) {
ret = copy_pidfd_info_to_user(pidfd, buf, count);
if (ret < 0)
return ret;
buf += ret;
count -= ret;
total_bytes += ret;
}
if (fanotify_is_error_event(event->mask)) {
ret = copy_error_info_to_user(event, buf, count);
if (ret < 0)
return ret;
buf += ret;
count -= ret;
total_bytes += ret;
}
return total_bytes;
}
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;
const struct path *path = fanotify_event_path(event);
struct fanotify_info *info = fanotify_event_info(event);
unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
struct file *f = NULL;
int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
metadata.event_len = fanotify_event_len(info_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);
/*
* For an unprivileged listener, event->pid can be used to identify the
* events generated by the listener process itself, without disclosing
* the pids of other processes.
*/
if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
task_tgid(current) != event->pid)
metadata.pid = 0;
/*
* For now, fid mode is required for an unprivileged listener and
* fid mode does not report fd in events. Keep this check anyway
* for safety in case fid mode requirement is relaxed in the future
* to allow unprivileged listener to get events with no fd and no fid.
*/
if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
path && path->mnt && path->dentry) {
fd = create_fd(group, path, &f);
if (fd < 0)
return fd;
}
metadata.fd = fd;
if (pidfd_mode) {
/*
* Complain if the FAN_REPORT_PIDFD and FAN_REPORT_TID mutual
* exclusion is ever lifted. At the time of incoporating pidfd
* support within fanotify, the pidfd API only supported the
* creation of pidfds for thread-group leaders.
*/
WARN_ON_ONCE(FAN_GROUP_FLAG(group, FAN_REPORT_TID));
/*
* The PIDTYPE_TGID check for an event->pid is performed
* preemptively in an attempt to catch out cases where the event
* listener reads events after the event generating process has
* already terminated. Report FAN_NOPIDFD to the event listener
* in those cases, with all other pidfd creation errors being
* reported as FAN_EPIDFD.
*/
if (metadata.pid == 0 ||
!pid_has_task(event->pid, PIDTYPE_TGID)) {
pidfd = FAN_NOPIDFD;
} else {
pidfd = pidfd_create(event->pid, 0);
if (pidfd < 0)
pidfd = FAN_EPIDFD;
}
}
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;
if (info_mode) {
ret = copy_info_records_to_user(event, info, info_mode, pidfd,
buf, count);
if (ret < 0)
goto out_close_fd;
}
if (f)
fd_install(fd, f);
return metadata.event_len;
out_close_fd:
if (fd != FAN_NOFD) {
put_unused_fd(fd);
fput(f);
}
if (pidfd >= 0)
close_fd(pidfd);
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;
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)) {
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 ((fsn_event = fsnotify_remove_first_event(group))) {
struct fanotify_event *event = FANOTIFY_E(fsn_event);
if (!(event->mask & FANOTIFY_PERM_EVENTS)) {
spin_unlock(&group->notification_lock);
fsnotify_destroy_event(group, fsn_event);
} 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 = path_permission(path, 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, newmask;
/* umask bits cannot be removed by user */
mask &= ~umask;
spin_lock(&fsn_mark->lock);
oldmask = fsnotify_calc_mask(fsn_mark);
if (!(flags & FANOTIFY_MARK_IGNORE_BITS)) {
fsn_mark->mask &= ~mask;
} else {
fsn_mark->ignore_mask &= ~mask;
}
newmask = fsnotify_calc_mask(fsn_mark);
/*
* 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->ignore_mask) & ~umask);
spin_unlock(&fsn_mark->lock);
return oldmask & ~newmask;
}
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;
fsnotify_group_lock(group);
fsn_mark = fsnotify_find_mark(connp, group);
if (!fsn_mark) {
fsnotify_group_unlock(group);
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);
fsnotify_group_unlock(group);
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 bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark,
unsigned int fan_flags)
{
bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE);
unsigned int ignore = fan_flags & FANOTIFY_MARK_IGNORE_BITS;
bool recalc = false;
/*
* When using FAN_MARK_IGNORE for the first time, mark starts using
* independent event flags in ignore mask. After that, trying to
* update the ignore mask with the old FAN_MARK_IGNORED_MASK API
* will result in EEXIST error.
*/
if (ignore == FAN_MARK_IGNORE)
fsn_mark->flags |= FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS;
/*
* Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to
* the removal of the FS_MODIFY bit in calculated mask if it was set
* because of an ignore mask that is now going to survive FS_MODIFY.
*/
if (ignore && (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
!(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) {
fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
if (!(fsn_mark->mask & FS_MODIFY))
recalc = true;
}
if (fsn_mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE ||
want_iref == !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF))
return recalc;
/*
* NO_IREF may be removed from a mark, but not added.
* When removed, fsnotify_recalc_mask() will take the inode ref.
*/
WARN_ON_ONCE(!want_iref);
fsn_mark->flags &= ~FSNOTIFY_MARK_FLAG_NO_IREF;
return true;
}
static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
__u32 mask, unsigned int fan_flags)
{
bool recalc;
spin_lock(&fsn_mark->lock);
if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS))
fsn_mark->mask |= mask;
else
fsn_mark->ignore_mask |= mask;
recalc = fsnotify_calc_mask(fsn_mark) &
~fsnotify_conn_mask(fsn_mark->connector);
recalc |= fanotify_mark_update_flags(fsn_mark, fan_flags);
spin_unlock(&fsn_mark->lock);
return recalc;
}
static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
fsnotify_connp_t *connp,
unsigned int obj_type,
unsigned int fan_flags,
__kernel_fsid_t *fsid)
{
struct ucounts *ucounts = group->fanotify_data.ucounts;
struct fsnotify_mark *mark;
int ret;
/*
* Enforce per user marks limits per user in all containing user ns.
* A group with FAN_UNLIMITED_MARKS does not contribute to mark count
* in the limited groups account.
*/
if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) &&
!inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS))
return ERR_PTR(-ENOSPC);
mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
if (!mark) {
ret = -ENOMEM;
goto out_dec_ucounts;
}
fsnotify_init_mark(mark, group);
if (fan_flags & FAN_MARK_EVICTABLE)
mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF;
ret = fsnotify_add_mark_locked(mark, connp, obj_type, 0, fsid);
if (ret) {
fsnotify_put_mark(mark);
goto out_dec_ucounts;
}
return mark;
out_dec_ucounts:
if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS))
dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS);
return ERR_PTR(ret);
}
static int fanotify_group_init_error_pool(struct fsnotify_group *group)
{
if (mempool_initialized(&group->fanotify_data.error_events_pool))
return 0;
return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool,
FANOTIFY_DEFAULT_FEE_POOL_SIZE,
sizeof(struct fanotify_error_event));
}
static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark,
unsigned int fan_flags)
{
/*
* Non evictable mark cannot be downgraded to evictable mark.
*/
if (fan_flags & FAN_MARK_EVICTABLE &&
!(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF))
return -EEXIST;
/*
* New ignore mask semantics cannot be downgraded to old semantics.
*/
if (fan_flags & FAN_MARK_IGNORED_MASK &&
fsn_mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
return -EEXIST;
/*
* An ignore mask that survives modify could never be downgraded to not
* survive modify. With new FAN_MARK_IGNORE semantics we make that rule
* explicit and return an error when trying to update the ignore mask
* without the original FAN_MARK_IGNORED_SURV_MODIFY value.
*/
if (fan_flags & FAN_MARK_IGNORE &&
!(fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
return -EEXIST;
return 0;
}
static int fanotify_add_mark(struct fsnotify_group *group,
fsnotify_connp_t *connp, unsigned int obj_type,
__u32 mask, unsigned int fan_flags,
__kernel_fsid_t *fsid)
{
struct fsnotify_mark *fsn_mark;
bool recalc;
int ret = 0;
fsnotify_group_lock(group);
fsn_mark = fsnotify_find_mark(connp, group);
if (!fsn_mark) {
fsn_mark = fanotify_add_new_mark(group, connp, obj_type,
fan_flags, fsid);
if (IS_ERR(fsn_mark)) {
fsnotify_group_unlock(group);
return PTR_ERR(fsn_mark);
}
}
/*
* Check if requested mark flags conflict with an existing mark flags.
*/
ret = fanotify_may_update_existing_mark(fsn_mark, fan_flags);
if (ret)
goto out;
/*
* Error events are pre-allocated per group, only if strictly
* needed (i.e. FAN_FS_ERROR was requested).
*/
if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS) &&
(mask & FAN_FS_ERROR)) {
ret = fanotify_group_init_error_pool(group);
if (ret)
goto out;
}
recalc = fanotify_mark_add_to_mask(fsn_mark, mask, fan_flags);
if (recalc)
fsnotify_recalc_mask(fsn_mark->connector);
out:
fsnotify_group_unlock(group);
fsnotify_put_mark(fsn_mark);
return ret;
}
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 ignore mask, unless that ignore mask is supposed to survive
* modification changes anyway.
*/
if ((flags & FANOTIFY_MARK_IGNORE_BITS) &&
!(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;
}
static struct hlist_head *fanotify_alloc_merge_hash(void)
{
struct hlist_head *hash;
hash = kmalloc(sizeof(struct hlist_head) << FANOTIFY_HTABLE_BITS,
GFP_KERNEL_ACCOUNT);
if (!hash)
return NULL;
__hash_init(hash, FANOTIFY_HTABLE_SIZE);
return hash;
}
/* fanotify syscalls */
SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
{
struct fsnotify_group *group;
int f_flags, fd;
unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
unsigned int class = flags & FANOTIFY_CLASS_BITS;
unsigned int internal_flags = 0;
pr_debug("%s: flags=%x event_f_flags=%x\n",
__func__, flags, event_f_flags);
if (!capable(CAP_SYS_ADMIN)) {
/*
* An unprivileged user can setup an fanotify group with
* limited functionality - an unprivileged group is limited to
* notification events with file handles and it cannot use
* unlimited queue/marks.
*/
if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode)
return -EPERM;
/*
* Setting the internal flag FANOTIFY_UNPRIV on the group
* prevents setting mount/filesystem marks on this group and
* prevents reporting pid and open fd in events.
*/
internal_flags |= FANOTIFY_UNPRIV;
}
#ifdef CONFIG_AUDITSYSCALL
if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT))
#else
if (flags & ~FANOTIFY_INIT_FLAGS)
#endif
return -EINVAL;
/*
* A pidfd can only be returned for a thread-group leader; thus
* FAN_REPORT_PIDFD and FAN_REPORT_TID need to remain mutually
* exclusive.
*/
if ((flags & FAN_REPORT_PIDFD) && (flags & FAN_REPORT_TID))
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;
/*
* FAN_REPORT_TARGET_FID requires FAN_REPORT_NAME and FAN_REPORT_FID
* and is used as an indication to report both dir and child fid on all
* dirent events.
*/
if ((fid_mode & FAN_REPORT_TARGET_FID) &&
(!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))
return -EINVAL;
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,
FSNOTIFY_GROUP_USER | FSNOTIFY_GROUP_NOFS);
if (IS_ERR(group)) {
return PTR_ERR(group);
}
/* Enforce groups limits per user in all containing user ns */
group->fanotify_data.ucounts = inc_ucount(current_user_ns(),
current_euid(),
UCOUNT_FANOTIFY_GROUPS);
if (!group->fanotify_data.ucounts) {
fd = -EMFILE;
goto out_destroy_group;
}
group->fanotify_data.flags = flags | internal_flags;
group->memcg = get_mem_cgroup_from_mm(current->mm);
group->fanotify_data.merge_hash = fanotify_alloc_merge_hash();
if (!group->fanotify_data.merge_hash) {
fd = -ENOMEM;
goto out_destroy_group;
}
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_max_queued_events;
}
if (flags & FAN_UNLIMITED_MARKS) {
fd = -EPERM;
if (!capable(CAP_SYS_ADMIN))
goto out_destroy_group;
}
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;
}
static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
{
__kernel_fsid_t root_fsid;
int err;
/*
* Make sure dentry is not of a filesystem with zero fsid (e.g. fuse).
*/
err = vfs_get_fsid(dentry, fsid);
if (err)
return err;
if (!fsid->val[0] && !fsid->val[1])
return -ENODEV;
/*
* Make sure dentry is not of a filesystem subvolume (e.g. btrfs)
* which uses a different fsid than sb root.
*/
err = vfs_get_fsid(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;
return 0;
}
/* Check if filesystem can encode a unique fid */
static int fanotify_test_fid(struct dentry *dentry)
{
/*
* 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 (!dentry->d_sb->s_export_op ||
!dentry->d_sb->s_export_op->fh_to_dentry)
return -EOPNOTSUPP;
return 0;
}
static int fanotify_events_supported(struct fsnotify_group *group,
const struct path *path, __u64 mask,
unsigned int flags)
{
unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
/* Strict validation of events in non-dir inode mask with v5.17+ APIs */
bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) ||
(mask & FAN_RENAME) ||
(flags & FAN_MARK_IGNORE);
/*
* 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;
/*
* mount and sb marks are not allowed on kernel internal pseudo fs,
* like pipe_mnt, because that would subscribe to events on all the
* anonynous pipes in the system.
*
* SB_NOUSER covers all of the internal pseudo fs whose objects are not
* exposed to user's mount namespace, but there are other SB_KERNMOUNT
* fs, like nsfs, debugfs, for which the value of allowing sb and mount
* mark is questionable. For now we leave them alone.
*/
if (mark_type != FAN_MARK_INODE &&
path->mnt->mnt_sb->s_flags & SB_NOUSER)
return -EINVAL;
/*
* We shouldn't have allowed setting dirent events and the directory
* flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode,
* but because we always allowed it, error only when using new APIs.
*/
if (strict_dir_events && mark_type == FAN_MARK_INODE &&
!d_is_dir(path->dentry) && (mask & FANOTIFY_DIRONLY_EVENT_BITS))
return -ENOTDIR;
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;
unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS;
unsigned int ignore = flags & FANOTIFY_MARK_IGNORE_BITS;
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 (upper_32_bits(mask))
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 (mark_cmd) {
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;
/* We don't allow FAN_MARK_IGNORE & FAN_MARK_IGNORED_MASK together */
if (ignore == (FAN_MARK_IGNORE | FAN_MARK_IGNORED_MASK))
return -EINVAL;
/*
* Event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) have no effect with
* FAN_MARK_IGNORED_MASK.
*/
if (ignore == FAN_MARK_IGNORED_MASK) {
mask &= ~FANOTIFY_EVENT_FLAGS;
umask = 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;
/*
* An unprivileged user is not allowed to setup mount nor filesystem
* marks. This also includes setting up such marks by a group that
* was initialized by an unprivileged user.
*/
ret = -EPERM;
if ((!capable(CAP_SYS_ADMIN) ||
FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) &&
mark_type != FAN_MARK_INODE)
goto fput_and_out;
/*
* 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;
if (mask & FAN_FS_ERROR &&
mark_type != FAN_MARK_FILESYSTEM)
goto fput_and_out;
/*
* Evictable is only relevant for inode marks, because only inode object
* can be evicted on memory pressure.
*/
if (flags & FAN_MARK_EVICTABLE &&
mark_type != FAN_MARK_INODE)
goto fput_and_out;
/*
* Events that do not carry enough information to report
* event->fd require a group that supports reporting fid. Those
* 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_FD_EVENTS|FANOTIFY_EVENT_FLAGS) &&
(!fid_mode || mark_type == FAN_MARK_MOUNT))
goto fput_and_out;
/*
* FAN_RENAME uses special info type records to report the old and
* new parent+name. Reporting only old and new parent id is less
* useful and was not implemented.
*/
if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME))
goto fput_and_out;
if (mark_cmd == 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 (mark_cmd == FAN_MARK_ADD) {
ret = fanotify_events_supported(group, &path, mask, flags);
if (ret)
goto path_put_and_out;
}
if (fid_mode) {
ret = fanotify_test_fsid(path.dentry, &__fsid);
if (ret)
goto path_put_and_out;
ret = fanotify_test_fid(path.dentry);
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;
ret = mnt ? -EINVAL : -EISDIR;
/* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */
if (mark_cmd == FAN_MARK_ADD && ignore == FAN_MARK_IGNORE &&
(mnt || S_ISDIR(inode->i_mode)) &&
!(flags & FAN_MARK_IGNORED_SURV_MODIFY))
goto path_put_and_out;
/* 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) && !ignore)
mask |= FAN_EVENT_ON_CHILD;
}
/* create/update an inode mark */
switch (mark_cmd) {
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)
{
struct sysinfo si;
int max_marks;
si_meminfo(&si);
/*
* Allow up to 1% of addressable memory to be accounted for per user
* marks limited to the range [8192, 1048576]. mount and sb marks are
* a lot cheaper than inode marks, but there is no reason for a user
* to have many of those, so calculate by the cost of inode marks.
*/
max_marks = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) /
INODE_MARK_COST;
max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS,
FANOTIFY_DEFAULT_MAX_USER_MARKS);
BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS);
BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 12);
BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11);
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);
}
fanotify_max_queued_events = FANOTIFY_DEFAULT_MAX_EVENTS;
init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] =
FANOTIFY_DEFAULT_MAX_GROUPS;
init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks;
return 0;
}
device_initcall(fanotify_user_setup);
Reference in New Issue View Git Blame Copy Permalink