FANOTIFY_MARK(2)          (2020-11-01)           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 permis-
          sion 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:

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          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 sym-
               bolic link.)

          FAN_MARK_ONLYDIR
               If the filesystem object to be marked is not a direc-
               tory, 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, subdirecto-
               ries, 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 filesys-
               tem containing pathname will be marked.  All the con-
               tained 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 mod-
               ify 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 follow-
          ing 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

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               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 direc-
               tory 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 cre-
               ated 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 han-
               dles 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 filesys-
               tem 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

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               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 gen-
               erated 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:

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          *  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.

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          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 con-
               figured 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 fan-
               otify 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 specifi-
          cally, this means that events of these types will be gener-
          ated 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).

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          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 inter-
          preter, respectively:

              /bin/echo
              /lib64/ld-linux-x86-64.so.2

     BUGS
          The following bugs were present in Linux kernels before ver-
          sion 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/.

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