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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
              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.   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.  This  value  cannot
              be  used if the fanotify_fd file descriptor has been initialized
              with the flag FAN_REPORT_FID or if any of the new directory mod‐
              ification  events  are  provided as a mask.  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
       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 exe‐
              cuted.  See NOTES for additional details.

       FAN_ATTRIB
              Create  an  event  when the metadata for a file or directory has
              changed.

       FAN_CREATE
              Create an event when a file or directory has been created  in  a
              marked parent directory.

       FAN_DELETE
              Create  an  event when a file or directory has been deleted in a
              marked parent directory.

       FAN_DELETE_SELF
              Create an event when  a  marked  file  or  directory  itself  is
              deleted.

       FAN_MOVED_FROM
              Create  an  event when a file or directory has been moved from a
              marked parent directory.

       FAN_MOVED_TO
              Create an event when a file or directory has  been  moved  to  a
              marked parent directory.

       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_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, only events for files  are  created.   The  FAN_ONDIR
              flag  is  reported in an event mask only if the fanotify_fd file
              descriptor has been initialized with  the  flag  FAN_REPORT_FID.
              In  the  context  of directory entry events, such as FAN_CREATE,
              FAN_DELETE, FAN_MOVED_FROM, and FAN_MOVED_TO for example, speci‐
              fying  the  flag FAN_ONDIR is required in order to create events
              when  subdirectory  entries  are   modified   (i.e.,   mkdir(2)/
              rmdir(2)).  Subdirectory entry modification events will never be
              merged with nonsubdirectory  entry  modification  events.   This
              flag  is  never  reported  individually  within  an event and is
              always supplied in conjunction with another event type.

       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.  To monitor complete
              directory trees it is necessary to mark the relevant mount.

       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).

       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
              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  CON‐
              FIG_FANOTIFY.

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

       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.

       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.

       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.

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
       script 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 5.02 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                             2019-08-02                  FANOTIFY_MARK(2)
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