linux-stable/include/linux/fanotify.h
Amir Goldstein e252f2ed1c fanotify: introduce FAN_MARK_IGNORE
This flag is a new way to configure ignore mask which allows adding and
removing the event flags FAN_ONDIR and FAN_EVENT_ON_CHILD in ignore mask.

The legacy FAN_MARK_IGNORED_MASK flag would always ignore events on
directories and would ignore events on children depending on whether
the FAN_EVENT_ON_CHILD flag was set in the (non ignored) mask.

FAN_MARK_IGNORE can be used to ignore events on children without setting
FAN_EVENT_ON_CHILD in the mark's mask and will not ignore events on
directories unconditionally, only when FAN_ONDIR is set in ignore mask.

The new behavior is non-downgradable.  After calling fanotify_mark() with
FAN_MARK_IGNORE once, calling fanotify_mark() with FAN_MARK_IGNORED_MASK
on the same object will return EEXIST error.

Setting the event flags with FAN_MARK_IGNORE on a non-dir inode mark
has no meaning and will return ENOTDIR error.

The meaning of FAN_MARK_IGNORED_SURV_MODIFY is preserved with the new
FAN_MARK_IGNORE flag, but with a few semantic differences:

1. FAN_MARK_IGNORED_SURV_MODIFY is required for filesystem and mount
   marks and on an inode mark on a directory. Omitting this flag
   will return EINVAL or EISDIR error.

2. An ignore mask on a non-directory inode that survives modify could
   never be downgraded to an ignore mask that does not survive modify.
   With new FAN_MARK_IGNORE semantics we make that rule explicit -
   trying to update a surviving ignore mask without the flag
   FAN_MARK_IGNORED_SURV_MODIFY will return EEXIST error.

The conveniene macro FAN_MARK_IGNORE_SURV is added for
(FAN_MARK_IGNORE | FAN_MARK_IGNORED_SURV_MODIFY), because the
common case should use short constant names.

Link: https://lore.kernel.org/r/20220629144210.2983229-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2022-07-01 14:53:01 +02:00

133 lines
4.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_FANOTIFY_H
#define _LINUX_FANOTIFY_H
#include <linux/sysctl.h>
#include <uapi/linux/fanotify.h>
#define FAN_GROUP_FLAG(group, flag) \
((group)->fanotify_data.flags & (flag))
/*
* Flags allowed to be passed from/to userspace.
*
* We intentionally do not add new bits to the old FAN_ALL_* constants, because
* they are uapi exposed constants. If there are programs out there using
* these constant, the programs may break if re-compiled with new uapi headers
* and then run on an old kernel.
*/
/* Group classes where permission events are allowed */
#define FANOTIFY_PERM_CLASSES (FAN_CLASS_CONTENT | \
FAN_CLASS_PRE_CONTENT)
#define FANOTIFY_CLASS_BITS (FAN_CLASS_NOTIF | FANOTIFY_PERM_CLASSES)
#define FANOTIFY_FID_BITS (FAN_REPORT_DFID_NAME_TARGET)
#define FANOTIFY_INFO_MODES (FANOTIFY_FID_BITS | FAN_REPORT_PIDFD)
/*
* fanotify_init() flags that require CAP_SYS_ADMIN.
* We do not allow unprivileged groups to request permission events.
* We do not allow unprivileged groups to get other process pid in events.
* We do not allow unprivileged groups to use unlimited resources.
*/
#define FANOTIFY_ADMIN_INIT_FLAGS (FANOTIFY_PERM_CLASSES | \
FAN_REPORT_TID | \
FAN_REPORT_PIDFD | \
FAN_UNLIMITED_QUEUE | \
FAN_UNLIMITED_MARKS)
/*
* fanotify_init() flags that are allowed for user without CAP_SYS_ADMIN.
* FAN_CLASS_NOTIF is the only class we allow for unprivileged group.
* We do not allow unprivileged groups to get file descriptors in events,
* so one of the flags for reporting file handles is required.
*/
#define FANOTIFY_USER_INIT_FLAGS (FAN_CLASS_NOTIF | \
FANOTIFY_FID_BITS | \
FAN_CLOEXEC | FAN_NONBLOCK)
#define FANOTIFY_INIT_FLAGS (FANOTIFY_ADMIN_INIT_FLAGS | \
FANOTIFY_USER_INIT_FLAGS)
/* Internal group flags */
#define FANOTIFY_UNPRIV 0x80000000
#define FANOTIFY_INTERNAL_GROUP_FLAGS (FANOTIFY_UNPRIV)
#define FANOTIFY_MARK_TYPE_BITS (FAN_MARK_INODE | FAN_MARK_MOUNT | \
FAN_MARK_FILESYSTEM)
#define FANOTIFY_MARK_CMD_BITS (FAN_MARK_ADD | FAN_MARK_REMOVE | \
FAN_MARK_FLUSH)
#define FANOTIFY_MARK_IGNORE_BITS (FAN_MARK_IGNORED_MASK | \
FAN_MARK_IGNORE)
#define FANOTIFY_MARK_FLAGS (FANOTIFY_MARK_TYPE_BITS | \
FANOTIFY_MARK_CMD_BITS | \
FANOTIFY_MARK_IGNORE_BITS | \
FAN_MARK_DONT_FOLLOW | \
FAN_MARK_ONLYDIR | \
FAN_MARK_IGNORED_SURV_MODIFY | \
FAN_MARK_EVICTABLE)
/*
* Events that can be reported with data type FSNOTIFY_EVENT_PATH.
* Note that FAN_MODIFY can also be reported with data type
* FSNOTIFY_EVENT_INODE.
*/
#define FANOTIFY_PATH_EVENTS (FAN_ACCESS | FAN_MODIFY | \
FAN_CLOSE | FAN_OPEN | FAN_OPEN_EXEC)
/*
* Directory entry modification events - reported only to directory
* where entry is modified and not to a watching parent.
*/
#define FANOTIFY_DIRENT_EVENTS (FAN_MOVE | FAN_CREATE | FAN_DELETE | \
FAN_RENAME)
/* Events that can be reported with event->fd */
#define FANOTIFY_FD_EVENTS (FANOTIFY_PATH_EVENTS | FANOTIFY_PERM_EVENTS)
/* Events that can only be reported with data type FSNOTIFY_EVENT_INODE */
#define FANOTIFY_INODE_EVENTS (FANOTIFY_DIRENT_EVENTS | \
FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
/* Events that can only be reported with data type FSNOTIFY_EVENT_ERROR */
#define FANOTIFY_ERROR_EVENTS (FAN_FS_ERROR)
/* Events that user can request to be notified on */
#define FANOTIFY_EVENTS (FANOTIFY_PATH_EVENTS | \
FANOTIFY_INODE_EVENTS | \
FANOTIFY_ERROR_EVENTS)
/* Events that require a permission response from user */
#define FANOTIFY_PERM_EVENTS (FAN_OPEN_PERM | FAN_ACCESS_PERM | \
FAN_OPEN_EXEC_PERM)
/* Extra flags that may be reported with event or control handling of events */
#define FANOTIFY_EVENT_FLAGS (FAN_EVENT_ON_CHILD | FAN_ONDIR)
/* Events that may be reported to user */
#define FANOTIFY_OUTGOING_EVENTS (FANOTIFY_EVENTS | \
FANOTIFY_PERM_EVENTS | \
FAN_Q_OVERFLOW | FAN_ONDIR)
/* Events and flags relevant only for directories */
#define FANOTIFY_DIRONLY_EVENT_BITS (FANOTIFY_DIRENT_EVENTS | \
FAN_EVENT_ON_CHILD | FAN_ONDIR)
#define ALL_FANOTIFY_EVENT_BITS (FANOTIFY_OUTGOING_EVENTS | \
FANOTIFY_EVENT_FLAGS)
/* Do not use these old uapi constants internally */
#undef FAN_ALL_CLASS_BITS
#undef FAN_ALL_INIT_FLAGS
#undef FAN_ALL_MARK_FLAGS
#undef FAN_ALL_EVENTS
#undef FAN_ALL_PERM_EVENTS
#undef FAN_ALL_OUTGOING_EVENTS
#endif /* _LINUX_FANOTIFY_H */