FANOTIFY_MARK(2) Linux Programmer's Manual FANOTIFY_MARK(2)
NAME
fanotify_mark - add, remove, or modify an fanotify mark on a filesystem
object
SYNOPSIS
#include <sys/fanotify.h>
int fanotify_mark(int fanotify_fd, unsigned int flags,
uint64_t mask, int dirfd, const char *pathname);
DESCRIPTION
For an overview of the fanotify API, see fanotify(7).
fanotify_mark() adds, removes, or modifies an fanotify mark on a
filesystem object. The caller must have read permission on the
filesystem object that is to be marked.
The fanotify_fd argument is a file descriptor returned by fan-
otify_init(2).
flags is a bit mask describing the modification to perform. It must
include exactly one of the following values:
FAN_MARK_ADD
The events in mask will be added to the mark mask (or to the ig-
nore mask). mask must be nonempty or the error EINVAL will oc-
cur.
FAN_MARK_REMOVE
The events in argument mask will be removed from the mark mask
(or from the ignore mask). mask must be nonempty or the error
EINVAL will occur.
FAN_MARK_FLUSH
Remove either all marks for filesystems, all marks for mounts,
or all marks for directories and files from the fanotify group.
If flags contains FAN_MARK_MOUNT, all marks for mounts are re-
moved from the group. If flags contains FAN_MARK_FILESYSTEM,
all marks for filesystems are removed from the group. Other-
wise, all marks for directories and files are removed. No flag
other than and at most one of the flags FAN_MARK_MOUNT or
FAN_MARK_FILESYSTEM can be used in conjunction with
FAN_MARK_FLUSH. mask is ignored.
If none of the values above is specified, or more than one is speci-
fied, the call fails with the error EINVAL.
In addition, zero or more of the following values may be ORed into
flags:
FAN_MARK_DONT_FOLLOW
If pathname is a symbolic link, mark the link itself, rather
than the file to which it refers. (By default, fanotify_mark()
dereferences pathname if it is a symbolic link.)
FAN_MARK_ONLYDIR
If the filesystem object to be marked is not a directory, the
error ENOTDIR shall be raised.
FAN_MARK_MOUNT
Mark the mount point specified by pathname. If pathname is not
itself a mount point, the mount point containing pathname will
be marked. All directories, subdirectories, and the contained
files of the mount point will be monitored. The events which
require that filesystem objects are identified by file handles,
such as FAN_CREATE, FAN_ATTRIB, FAN_MOVE, and FAN_DELETE_SELF,
cannot be provided as a mask when flags contains FAN_MARK_MOUNT.
Attempting to do so will result in the error EINVAL being re-
turned.
FAN_MARK_FILESYSTEM (since Linux 4.20)
Mark the filesystem specified by pathname. The filesystem con-
taining pathname will be marked. All the contained files and
directories of the filesystem from any mount point will be moni-
tored.
FAN_MARK_IGNORED_MASK
The events in mask shall be added to or removed from the ignore
mask.
FAN_MARK_IGNORED_SURV_MODIFY
The ignore mask shall survive modify events. If this flag is
not set, the ignore mask is cleared when a modify event occurs
for the ignored file or directory.
mask defines which events shall be listened for (or which shall be ig-
nored). It is a bit mask composed of the following values:
FAN_ACCESS
Create an event when a file or directory (but see BUGS) is ac-
cessed (read).
FAN_MODIFY
Create an event when a file is modified (write).
FAN_CLOSE_WRITE
Create an event when a writable file is closed.
FAN_CLOSE_NOWRITE
Create an event when a read-only file or directory is closed.
FAN_OPEN
Create an event when a file or directory is opened.
FAN_OPEN_EXEC (since Linux 5.0)
Create an event when a file is opened with the intent to be exe-
cuted. See NOTES for additional details.
FAN_ATTRIB (since Linux 5.1)
Create an event when the metadata for a file or directory has
changed. An fanotify group that identifies filesystem objects
by file handles is required.
FAN_CREATE (since Linux 5.1)
Create an event when a file or directory has been created in a
marked parent directory. An fanotify group that identifies
filesystem objects by file handles is required.
FAN_DELETE (since Linux 5.1)
Create an event when a file or directory has been deleted in a
marked parent directory. An fanotify group that identifies
filesystem objects by file handles is required.
FAN_DELETE_SELF (since Linux 5.1)
Create an event when a marked file or directory itself is
deleted. An fanotify group that identifies filesystem objects
by file handles is required.
FAN_MOVED_FROM (since Linux 5.1)
Create an event when a file or directory has been moved from a
marked parent directory. An fanotify group that identifies
filesystem objects by file handles is required.
FAN_MOVED_TO (since Linux 5.1)
Create an event when a file or directory has been moved to a
marked parent directory. An fanotify group that identifies
filesystem objects by file handles is required.
FAN_MOVE_SELF (since Linux 5.1)
Create an event when a marked file or directory itself has been
moved. An fanotify group that identifies filesystem objects by
file handles is required.
FAN_OPEN_PERM
Create an event when a permission to open a file or directory is
requested. An fanotify file descriptor created with
FAN_CLASS_PRE_CONTENT or FAN_CLASS_CONTENT is required.
FAN_OPEN_EXEC_PERM (since Linux 5.0)
Create an event when a permission to open a file for execution
is requested. An fanotify file descriptor created with
FAN_CLASS_PRE_CONTENT or FAN_CLASS_CONTENT is required. See
NOTES for additional details.
FAN_ACCESS_PERM
Create an event when a permission to read a file or directory is
requested. An fanotify file descriptor created with
FAN_CLASS_PRE_CONTENT or FAN_CLASS_CONTENT is required.
FAN_ONDIR
Create events for directories—for example, when opendir(3),
readdir(3) (but see BUGS), and closedir(3) are called. Without
this flag, events are created only for files. In the context of
directory entry events, such as FAN_CREATE, FAN_DELETE,
FAN_MOVED_FROM, and FAN_MOVED_TO, specifying the flag FAN_ONDIR
is required in order to create events when subdirectory entries
are modified (i.e., mkdir(2)/ rmdir(2)).
FAN_EVENT_ON_CHILD
Events for the immediate children of marked directories shall be
created. The flag has no effect when marking mounts and
filesystems. Note that events are not generated for children of
the subdirectories of marked directories. More specifically,
the directory entry modification events FAN_CREATE, FAN_DELETE,
FAN_MOVED_FROM, and FAN_MOVED_TO are not generated for any entry
modifications performed inside subdirectories of marked directo-
ries. Note that the events FAN_DELETE_SELF and FAN_MOVE_SELF
are not generated for children of marked directories. To moni-
tor complete directory trees it is necessary to mark the rele-
vant mount or filesystem.
The following composed values are defined:
FAN_CLOSE
A file is closed (FAN_CLOSE_WRITE|FAN_CLOSE_NOWRITE).
FAN_MOVE
A file or directory has been moved
(FAN_MOVED_FROM|FAN_MOVED_TO).
The filesystem object to be marked is determined by the file descriptor
dirfd and the pathname specified in pathname:
* If pathname is NULL, dirfd defines the filesystem object to be
marked.
* If pathname is NULL, and dirfd takes the special value AT_FDCWD, the
current working directory is to be marked.
* If pathname is absolute, it defines the filesystem object to be
marked, and dirfd is ignored.
* If pathname is relative, and dirfd does not have the value AT_FDCWD,
then the filesystem object to be marked is determined by interpret-
ing pathname relative the directory referred to by dirfd.
* If pathname is relative, and dirfd has the value AT_FDCWD, then the
filesystem object to be marked is determined by interpreting path-
name relative the current working directory.
RETURN VALUE
On success, fanotify_mark() returns 0. On error, -1 is returned, and
errno is set to indicate the error.
ERRORS
EBADF An invalid file descriptor was passed in fanotify_fd.
EINVAL An invalid value was passed in flags or mask, or fanotify_fd was
not an fanotify file descriptor.
EINVAL The fanotify file descriptor was opened with FAN_CLASS_NOTIF or
the fanotify group identifies filesystem objects by file handles
and mask contains a flag for permission events (FAN_OPEN_PERM or
FAN_ACCESS_PERM).
ENODEV The filesystem object indicated by pathname is not associated
with a filesystem that supports fsid (e.g., tmpfs(5)). This er-
ror can be returned only with an fanotify group that identifies
filesystem objects by file handles.
ENOENT The filesystem object indicated by dirfd and pathname does not
exist. This error also occurs when trying to remove a mark from
an object which is not marked.
ENOMEM The necessary memory could not be allocated.
ENOSPC The number of marks exceeds the limit of 8192 and the FAN_UNLIM-
ITED_MARKS flag was not specified when the fanotify file de-
scriptor was created with fanotify_init(2).
ENOSYS This kernel does not implement fanotify_mark(). The fanotify
API is available only if the kernel was configured with CON-
FIG_FANOTIFY.
ENOTDIR
flags contains FAN_MARK_ONLYDIR, and dirfd and pathname do not
specify a directory.
EOPNOTSUPP
The object indicated by pathname is associated with a filesystem
that does not support the encoding of file handles. This error
can be returned only with an fanotify group that identifies
filesystem objects by file handles.
EXDEV The filesystem object indicated by pathname resides within a
filesystem subvolume (e.g., btrfs(5)) which uses a different
fsid than its root superblock. This error can be returned only
with an fanotify group that identifies filesystem objects by
file handles.
VERSIONS
fanotify_mark() was introduced in version 2.6.36 of the Linux kernel
and enabled in version 2.6.37.
CONFORMING TO
This system call is Linux-specific.
NOTES
FAN_OPEN_EXEC and FAN_OPEN_EXEC_PERM
When using either FAN_OPEN_EXEC or FAN_OPEN_EXEC_PERM within the mask,
events of these types will be returned only when the direct execution
of a program occurs. More specifically, this means that events of
these types will be generated for files that are opened using ex-
ecve(2), execveat(2), or uselib(2). Events of these types will not be
raised in the situation where an interpreter is passed (or reads) a
file for interpretation.
Additionally, if a mark has also been placed on the Linux dynamic
linker, a user should also expect to receive an event for it when an
ELF object has been successfully opened using execve(2) or execveat(2).
For example, if the following ELF binary were to be invoked and a
FAN_OPEN_EXEC mark has been placed on /:
$ /bin/echo foo
The listening application in this case would receive FAN_OPEN_EXEC
events for both the ELF binary and interpreter, respectively:
/bin/echo
/lib64/ld-linux-x86-64.so.2
BUGS
The following bugs were present in Linux kernels before version 3.16:
* If flags contains FAN_MARK_FLUSH, dirfd, and pathname must specify a
valid filesystem object, even though this object is not used.
* readdir(2) does not generate a FAN_ACCESS event.
* If fanotify_mark() is called with FAN_MARK_FLUSH, flags is not
checked for invalid values.
SEE ALSO
fanotify_init(2), fanotify(7)
COLOPHON
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