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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 5.10 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/.