fanotify_mark(2) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | NOTES | BUGS | SEE ALSO | COLOPHON

FANOTIFY_MARK(2)          Linux Programmer's Manual         FANOTIFY_MARK(2)

NAME         top

       fanotify_mark - add, remove, or modify an fanotify mark on a filesys‐
       tem object

SYNOPSIS         top

       #include <sys/fanotify.h>

       int fanotify_mark(int fanotify_fd, unsigned int flags,
                         uint64_t mask, int dirfd, const char *pathname);

DESCRIPTION         top

       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 the fanotify_fd file descriptor to have
              been initialized with the flag FAN_REPORT_FID, 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 file descriptor created with
              FAN_REPORT_FID 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 file descriptor created
              with FAN_REPORT_FID 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 file descriptor created
              with FAN_REPORT_FID is required.

       FAN_DELETE_SELF (since Linux 5.1)
              Create an event when a marked file or directory itself is
              deleted.  An fanotify file descriptor created with
              FAN_REPORT_FID 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 file descriptor created
              with FAN_REPORT_FID 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 file descriptor created
              with FAN_REPORT_FID is required.

       FAN_MOVE_SELF (since Linux 5.1)
              Create an event when a marked file or directory itself has
              been moved.  An fanotify file descriptor created with
              FAN_REPORT_FID 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         top

       On success, fanotify_mark() returns 0.  On error, -1 is returned, and
       errno is set to indicate the error.

ERRORS         top

       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
              error can be returned only when an fanotify file descriptor
              returned 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_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 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         top

       fanotify_mark() was introduced in version 2.6.36 of the Linux kernel
       and enabled in version 2.6.37.

CONFORMING TO         top

       This system call is Linux-specific.

NOTES         top

   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         top

       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         top

       fanotify_init(2), fanotify(7)

COLOPHON         top

       This page is part of release 5.08 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                            2020-06-09                 FANOTIFY_MARK(2)

Pages that refer to this page: creat(2)fanotify_init(2)open(2)openat(2)syscalls(2)proc(5)procfs(5)fanotify(7)