fanotify_mark
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. This value cannot
be used if the fanotify_fd file descriptor has been initialized
with the flag FAN_REPORT_FID or if any of the new directory mod-
ification events are provided as a mask. Attempting to do so
will result in the error EINVAL being returned.
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.
FAN_CREATE (since Linux 5.1)
Create an event when a file or directory has been created in a
marked parent directory.
FAN_DELETE (since Linux 5.1)
Create an event when a file or directory has been deleted in a
marked parent directory.
FAN_DELETE_SELF (since Linux 5.1)
Create an event when a marked file or directory itself is
deleted.
FAN_MOVED_FROM (since Linux 5.1)
Create an event when a file or directory has been moved from a
marked parent directory.
FAN_MOVED_TO (since Linux 5.1)
Create an event when a file or directory has been moved to a
marked parent directory.
FAN_MOVE_SELF (since Linux 5.1)
Create an event when a marked file or directory itself has been
moved.
FAN_Q_OVERFLOW
Create an event when an overflow of the event queue occurs. The
size of the event queue is limited to 16384 entries if FAN_UN-
LIMITED_QUEUE is not set in fanotify_init(2).
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, only events for files are created. The FAN_ONDIR
flag is reported in an event mask only if the fanotify_fd file
descriptor has been initialized with the flag FAN_REPORT_FID.
In the context of directory entry events, such as FAN_CREATE,
FAN_DELETE, FAN_MOVED_FROM, and FAN_MOVED_TO for example, speci-
fying the flag FAN_ONDIR is required in order to create events
when subdirectory entries are modified (i.e., mkdir(2)/
rmdir(2)). Subdirectory entry modification events will never be
merged with nonsubdirectory entry modification events. This
flag is never reported individually within an event and is al-
ways supplied in conjunction with another event type.
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. To monitor complete
directory trees it is necessary to mark the relevant mount.
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
FAN_REPORT_FID 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 when an fanotify file descriptor re-
turned by fanotify_init(2) has been created with FAN_REPORT_FID.
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 when an fanotify file descriptor returned
by fanotify_init(2) has been created with FAN_REPORT_FID.
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
when an fanotify file descriptor returned by fanotify_init(2)
has been created with FAN_REPORT_FID.
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
script 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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Linux 2019-08-02 FANOTIFY_MARK(2)
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