1FANOTIFY_MARK(2)           Linux Programmer's Manual          FANOTIFY_MARK(2)
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NAME

6       fanotify_mark - add, remove, or modify an fanotify mark on a filesystem
7       object
8

SYNOPSIS

10       #include <sys/fanotify.h>
11
12       int fanotify_mark(int fanotify_fd, unsigned int flags,
13                         uint64_t mask, int dirfd, const char *pathname);
14

DESCRIPTION

16       For an overview of the fanotify API, see fanotify(7).
17
18       fanotify_mark() adds, removes,  or  modifies  an  fanotify  mark  on  a
19       filesystem  object.   The  caller  must  have  read  permission  on the
20       filesystem object that is to be marked.
21
22       The  fanotify_fd  argument  is  a  file  descriptor  returned  by  fan‐
23       otify_init(2).
24
25       flags  is  a  bit mask describing the modification to perform.  It must
26       include exactly one of the following values:
27
28       FAN_MARK_ADD
29              The events in mask will be added to the mark mask (or to the ig‐
30              nore  mask).  mask must be nonempty or the error EINVAL will oc‐
31              cur.
32
33       FAN_MARK_REMOVE
34              The events in argument mask will be removed from the  mark  mask
35              (or  from  the ignore mask).  mask must be nonempty or the error
36              EINVAL will occur.
37
38       FAN_MARK_FLUSH
39              Remove either all marks for filesystems, all marks  for  mounts,
40              or  all marks for directories and files from the fanotify group.
41              If flags contains FAN_MARK_MOUNT, all marks for mounts  are  re‐
42              moved  from  the  group.  If flags contains FAN_MARK_FILESYSTEM,
43              all marks for filesystems are removed from  the  group.   Other‐
44              wise,  all marks for directories and files are removed.  No flag
45              other than and at  most  one  of  the  flags  FAN_MARK_MOUNT  or
46              FAN_MARK_FILESYSTEM    can   be   used   in   conjunction   with
47              FAN_MARK_FLUSH.  mask is ignored.
48
49       If none of the values above is specified, or more than  one  is  speci‐
50       fied, the call fails with the error EINVAL.
51
52       In  addition,  zero  or  more  of the following values may be ORed into
53       flags:
54
55       FAN_MARK_DONT_FOLLOW
56              If pathname is a symbolic link, mark  the  link  itself,  rather
57              than  the file to which it refers.  (By default, fanotify_mark()
58              dereferences pathname if it is a symbolic link.)
59
60       FAN_MARK_ONLYDIR
61              If the filesystem object to be marked is not  a  directory,  the
62              error ENOTDIR shall be raised.
63
64       FAN_MARK_MOUNT
65              Mark  the mount point specified by pathname.  If pathname is not
66              itself a mount point, the mount point containing  pathname  will
67              be  marked.   All directories, subdirectories, and the contained
68              files of the mount point will be monitored.   The  events  which
69              require  that filesystem objects are identified by file handles,
70              such as FAN_CREATE, FAN_ATTRIB, FAN_MOVE,  and  FAN_DELETE_SELF,
71              cannot be provided as a mask when flags contains FAN_MARK_MOUNT.
72              Attempting to do so will result in the error  EINVAL  being  re‐
73              turned.
74
75       FAN_MARK_FILESYSTEM (since Linux 4.20)
76              Mark  the filesystem specified by pathname.  The filesystem con‐
77              taining pathname will be marked.  All the  contained  files  and
78              directories of the filesystem from any mount point will be moni‐
79              tored.
80
81       FAN_MARK_IGNORED_MASK
82              The events in mask shall be added to or removed from the  ignore
83              mask.
84
85       FAN_MARK_IGNORED_SURV_MODIFY
86              The  ignore  mask  shall survive modify events.  If this flag is
87              not set, the ignore mask is cleared when a modify  event  occurs
88              for the ignored file or directory.
89
90       mask  defines which events shall be listened for (or which shall be ig‐
91       nored).  It is a bit mask composed of the following values:
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93       FAN_ACCESS
94              Create an event when a file or directory (but see BUGS)  is  ac‐
95              cessed (read).
96
97       FAN_MODIFY
98              Create an event when a file is modified (write).
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100       FAN_CLOSE_WRITE
101              Create an event when a writable file is closed.
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103       FAN_CLOSE_NOWRITE
104              Create an event when a read-only file or directory is closed.
105
106       FAN_OPEN
107              Create an event when a file or directory is opened.
108
109       FAN_OPEN_EXEC (since Linux 5.0)
110              Create an event when a file is opened with the intent to be exe‐
111              cuted.  See NOTES for additional details.
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113       FAN_ATTRIB (since Linux 5.1)
114              Create an event when the metadata for a file  or  directory  has
115              changed.   An  fanotify group that identifies filesystem objects
116              by file handles is required.
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118       FAN_CREATE (since Linux 5.1)
119              Create an event when a file or directory has been created  in  a
120              marked  parent  directory.   An  fanotify  group that identifies
121              filesystem objects by file handles is required.
122
123       FAN_DELETE (since Linux 5.1)
124              Create an event when a file or directory has been deleted  in  a
125              marked  parent  directory.   An  fanotify  group that identifies
126              filesystem objects by file handles is required.
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128       FAN_DELETE_SELF (since Linux 5.1)
129              Create an event when  a  marked  file  or  directory  itself  is
130              deleted.   An  fanotify group that identifies filesystem objects
131              by file handles is required.
132
133       FAN_MOVED_FROM (since Linux 5.1)
134              Create an event when a file or directory has been moved  from  a
135              marked  parent  directory.   An  fanotify  group that identifies
136              filesystem objects by file handles is required.
137
138       FAN_MOVED_TO (since Linux 5.1)
139              Create an event when a file or directory has  been  moved  to  a
140              marked  parent  directory.   An  fanotify  group that identifies
141              filesystem objects by file handles is required.
142
143       FAN_MOVE_SELF (since Linux 5.1)
144              Create an event when a marked file or directory itself has  been
145              moved.   An fanotify group that identifies filesystem objects by
146              file handles is required.
147
148       FAN_OPEN_PERM
149              Create an event when a permission to open a file or directory is
150              requested.    An   fanotify   file   descriptor   created   with
151              FAN_CLASS_PRE_CONTENT or FAN_CLASS_CONTENT is required.
152
153       FAN_OPEN_EXEC_PERM (since Linux 5.0)
154              Create an event when a permission to open a file  for  execution
155              is   requested.    An  fanotify  file  descriptor  created  with
156              FAN_CLASS_PRE_CONTENT or  FAN_CLASS_CONTENT  is  required.   See
157              NOTES for additional details.
158
159       FAN_ACCESS_PERM
160              Create an event when a permission to read a file or directory is
161              requested.    An   fanotify   file   descriptor   created   with
162              FAN_CLASS_PRE_CONTENT or FAN_CLASS_CONTENT is required.
163
164       FAN_ONDIR
165              Create  events  for  directories—for  example,  when opendir(3),
166              readdir(3) (but see BUGS), and closedir(3) are called.   Without
167              this flag, events are created only for files.  In the context of
168              directory  entry  events,  such   as   FAN_CREATE,   FAN_DELETE,
169              FAN_MOVED_FROM,  and FAN_MOVED_TO, specifying the flag FAN_ONDIR
170              is required in order to create events when subdirectory  entries
171              are modified (i.e., mkdir(2)/ rmdir(2)).
172
173       FAN_EVENT_ON_CHILD
174              Events for the immediate children of marked directories shall be
175              created.  The  flag  has  no  effect  when  marking  mounts  and
176              filesystems.  Note that events are not generated for children of
177              the subdirectories of marked  directories.   More  specifically,
178              the  directory entry modification events FAN_CREATE, FAN_DELETE,
179              FAN_MOVED_FROM, and FAN_MOVED_TO are not generated for any entry
180              modifications performed inside subdirectories of marked directo‐
181              ries.  Note that the events  FAN_DELETE_SELF  and  FAN_MOVE_SELF
182              are  not generated for children of marked directories.  To moni‐
183              tor complete directory trees it is necessary to mark  the  rele‐
184              vant mount or filesystem.
185
186       The following composed values are defined:
187
188       FAN_CLOSE
189              A file is closed (FAN_CLOSE_WRITE|FAN_CLOSE_NOWRITE).
190
191       FAN_MOVE
192              A      file      or      directory      has      been      moved
193              (FAN_MOVED_FROM|FAN_MOVED_TO).
194
195       The filesystem object to be marked is determined by the file descriptor
196       dirfd and the pathname specified in pathname:
197
198       *  If  pathname  is  NULL,  dirfd  defines  the filesystem object to be
199          marked.
200
201       *  If pathname is NULL, and dirfd takes the special value AT_FDCWD, the
202          current working directory is to be marked.
203
204       *  If  pathname  is  absolute,  it  defines the filesystem object to be
205          marked, and dirfd is ignored.
206
207       *  If pathname is relative, and dirfd does not have the value AT_FDCWD,
208          then  the filesystem object to be marked is determined by interpret‐
209          ing pathname relative the directory referred to by dirfd.
210
211       *  If pathname is relative, and dirfd has the value AT_FDCWD, then  the
212          filesystem  object  to be marked is determined by interpreting path‐
213          name relative the current working directory.
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RETURN VALUE

216       On success, fanotify_mark() returns 0.  On error, -1 is  returned,  and
217       errno is set to indicate the error.
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ERRORS

220       EBADF  An invalid file descriptor was passed in fanotify_fd.
221
222       EINVAL An invalid value was passed in flags or mask, or fanotify_fd was
223              not an fanotify file descriptor.
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225       EINVAL The fanotify file descriptor was opened with FAN_CLASS_NOTIF  or
226              the fanotify group identifies filesystem objects by file handles
227              and mask contains a flag for permission events (FAN_OPEN_PERM or
228              FAN_ACCESS_PERM).
229
230       ENODEV The  filesystem  object  indicated by pathname is not associated
231              with a filesystem that supports fsid (e.g., tmpfs(5)).  This er‐
232              ror  can be returned only with an fanotify group that identifies
233              filesystem objects by file handles.
234
235       ENOENT The filesystem object indicated by dirfd and pathname  does  not
236              exist.  This error also occurs when trying to remove a mark from
237              an object which is not marked.
238
239       ENOMEM The necessary memory could not be allocated.
240
241       ENOSPC The number of marks exceeds the limit of 8192 and the FAN_UNLIM‐
242              ITED_MARKS  flag  was  not  specified when the fanotify file de‐
243              scriptor was created with fanotify_init(2).
244
245       ENOSYS This kernel does not implement  fanotify_mark().   The  fanotify
246              API  is  available  only  if the kernel was configured with CON‐
247              FIG_FANOTIFY.
248
249       ENOTDIR
250              flags contains FAN_MARK_ONLYDIR, and dirfd and pathname  do  not
251              specify a directory.
252
253       EOPNOTSUPP
254              The object indicated by pathname is associated with a filesystem
255              that does not support the encoding of file handles.  This  error
256              can  be  returned  only  with  an fanotify group that identifies
257              filesystem objects by file handles.
258
259       EXDEV  The filesystem object indicated by  pathname  resides  within  a
260              filesystem  subvolume  (e.g.,  btrfs(5))  which uses a different
261              fsid than its root superblock.  This error can be returned  only
262              with  an  fanotify  group  that identifies filesystem objects by
263              file handles.
264

VERSIONS

266       fanotify_mark() was introduced in version 2.6.36 of  the  Linux  kernel
267       and enabled in version 2.6.37.
268

CONFORMING TO

270       This system call is Linux-specific.
271

NOTES

273   FAN_OPEN_EXEC and FAN_OPEN_EXEC_PERM
274       When  using either FAN_OPEN_EXEC or FAN_OPEN_EXEC_PERM within the mask,
275       events of these types will be returned only when the  direct  execution
276       of  a  program  occurs.   More  specifically, this means that events of
277       these types will be generated for  files  that  are  opened  using  ex‐
278       ecve(2),  execveat(2), or uselib(2).  Events of these types will not be
279       raised in the situation where an interpreter is  passed  (or  reads)  a
280       file for interpretation.
281
282       Additionally,  if  a  mark  has  also  been placed on the Linux dynamic
283       linker, a user should also expect to receive an event for  it  when  an
284       ELF object has been successfully opened using execve(2) or execveat(2).
285
286       For  example,  if  the  following  ELF  binary were to be invoked and a
287       FAN_OPEN_EXEC mark has been placed on /:
288
289           $ /bin/echo foo
290
291       The listening application in  this  case  would  receive  FAN_OPEN_EXEC
292       events for both the ELF binary and interpreter, respectively:
293
294           /bin/echo
295           /lib64/ld-linux-x86-64.so.2
296

BUGS

298       The following bugs were present in Linux kernels before version 3.16:
299
300       *  If flags contains FAN_MARK_FLUSH, dirfd, and pathname must specify a
301          valid filesystem object, even though this object is not used.
302
303       *  readdir(2) does not generate a FAN_ACCESS event.
304
305       *  If fanotify_mark() is  called  with  FAN_MARK_FLUSH,  flags  is  not
306          checked for invalid values.
307

SEE ALSO

309       fanotify_init(2), fanotify(7)
310

COLOPHON

312       This  page  is  part of release 5.12 of the Linux man-pages project.  A
313       description of the project, information about reporting bugs,  and  the
314       latest     version     of     this    page,    can    be    found    at
315       https://www.kernel.org/doc/man-pages/.
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319Linux                             2021-03-22                  FANOTIFY_MARK(2)
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