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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.  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 modification 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 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
              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,  specifying  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  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 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_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.

       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/.