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
       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 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 removed
              from the group.  If flags contains FAN_MARK_FILESYSTEM, all marks
              for filesystems are removed from the group.  Otherwise, 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 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.  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 returned.

       FAN_MARK_FILESYSTEM (since Linux 4.20)
              Mark the filesystem specified by pathname.  The filesystem
              containing pathname will be marked.  All the contained files and
              directories of the filesystem from any 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_OPEN_EXEC (since Linux 5.0)
              Create an event when a file is opened with the intent to be
              executed.  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
              directories.  Note that the events FAN_DELETE_SELF and
              FAN_MOVE_SELF are not generated for children of marked
              directories.  To monitor complete directory trees it is necessary
              to mark the relevant 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 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 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 error 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_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.

       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 execve(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
       This page is part of release 5.12 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/.



Linux                              2021-03-22                   FANOTIFY_MARK(2)