FANOTIFY_MARK(2)



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.   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 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.   An  fanotify  file  descriptor  created  with FAN_RE-
              PORT_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_RE-
              PORT_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 directo-
              ries.  Note that the events  FAN_DELETE_SELF  and  FAN_MOVE_SELF
              are  not generated for children of marked directories.  To moni-
              tor complete directory trees it is necessary to mark  the  rele-
              vant 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 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
       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 5.07 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)

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