Ubuntu Manpage: fanotify_mark - add, remove, or modify an fanotify mark on a filesystem object

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 fanotify_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 ignore mask). mask
must be nonempty or the error EINVAL will occur.

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 mount or all non-mount marks from the fanotify group. If flags
contains FAN_MARK_MOUNT, all marks for mounts are removed from the group.
Otherwise, all marks for directories and files are removed. No flag other than
FAN_MARK_MOUNT 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 specified, 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.

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 ignored). It is a bit
mask composed of the following values:

FAN_ACCESS
Create an event when a file or directory (but see BUGS) is accessed (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_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_UNLIMITED_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_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.

FAN_EVENT_ON_CHILD
Events for the immediate children of marked directories shall be created. The flag
has no effect when marking mounts. 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 value is defined:

FAN_CLOSE
A file is closed (FAN_CLOSE_WRITE|FAN_CLOSE_NOWRITE).

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 interpreting 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 pathname 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 and  mask  contains  a
              flag for permission events (FAN_OPEN_PERM or FAN_ACCESS_PERM).

       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_UNLIMITED_MARKS flag  was
              not specified when the fanotify file descriptor 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 CONFIG_FANOTIFY.

       ENOTDIR
              flags contains FAN_MARK_ONLYDIR, and dirfd and pathname do not specify a directory.

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.

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.

COLOPHON

       This  page  is  part of release 4.15 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at https://www.kernel.org/doc/man-pages/.