1AUDITCTL:(8)            System Administration Utilities           AUDITCTL:(8)
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3
4

NAME

6       auditctl - a utility to assist controlling the kernel's audit system
7

SYNOPSIS

9       auditctl [options]
10

DESCRIPTION

12       The  auditctl  program  is  used to configure kernel options related to
13       auditing, to see status of the configuration, and to load discretionary
14       audit rules.
15

CONFIGURATION OPTIONS

17       -b backlog
18              Set  max  number  of  outstanding  audit buffers allowed (Kernel
19              Default=64) If all buffers are full, the failure  flag  is  con‐
20              sulted by the kernel for action.
21
22       --backlog_wait_time wait_time
23              Set  the time for the kernel to wait (Kernel Default 60*HZ) when
24              the backlog_limit is reached before queuing more audit events to
25              be  transferred  to  auditd.  The number must be greater than or
26              equal to zero and less that 10 times the default value.
27
28       -c     Continue loading rules in spite of an error. This summarizes the
29              results  of loading the rules. The exit code will not be success
30              if any rule fails to load.
31
32       -D     Delete all rules and watches. This can take a key  option  (-k),
33              too.
34
35       -e [0..2]
36              Set  enabled  flag. When 0 is passed, this can be used to tempo‐
37              rarily disable auditing. When 1 is passed  as  an  argument,  it
38              will enable auditing. To lock the audit configuration so that it
39              can't be changed, pass a 2 as the argument. Locking the configu‐
40              ration  is  intended  to  be the last command in audit.rules for
41              anyone wishing this feature to be active. Any attempt to  change
42              the  configuration  in this mode will be audited and denied. The
43              configuration can only be changed by rebooting the machine.
44
45       -f [0..2]
46              Set failure mode 0=silent 1=printk 2=panic. This option lets you
47              determine  how  you  want  the kernel to handle critical errors.
48              Example conditions where this mode may have an effect  includes:
49              transmission  errors  to  userspace  audit daemon, backlog limit
50              exceeded, out of kernel memory, and  rate  limit  exceeded.  The
51              default  value  is  1. Secure environments will probably want to
52              set this to 2.
53
54       -h     Help
55
56       -i     When given by itself, ignore errors when reading  rules  from  a
57              file. This causes auditctl to always return a success exit code.
58              If passed as an argument to -s then it gives  an  interpretation
59              of the numbers to human readable words if possible.
60
61       --loginuid-immutable
62              This option tells the kernel to make loginuids unchangeable once
63              they are set. Changing loginuids requires CAP_AUDIT_CONTROL. So,
64              its  not  something that can be done by unprivileged users. Set‐
65              ting this makes loginuid tamper-proof, but can cause some  prob‐
66              lems in certain kinds of containers.
67
68       -q mount-point,subtree
69              If  you  have an existing directory watch and bind or move mount
70              another subtree in the watched subtree, you  need  to  tell  the
71              kernel  to  make  the  subtree  being  mounted equivalent to the
72              directory being watched. If the subtree is  already  mounted  at
73              the time the directory watch is issued, the subtree is automati‐
74              cally tagged for watching. Please note the comma separating  the
75              two values. Omitting it will cause errors.
76
77       -r rate
78              Set limit in messages/sec (0=none). If this rate is non-zero and
79              is exceeded, the failure flag is consulted  by  the  kernel  for
80              action. The default value is 0.
81
82       --reset-lost
83              Reset the lost record counter shown by the status command.
84
85       -R file
86              Read  rules from a file. The rules must be 1 per line and in the
87              order that they are to be executed in. The  rule  file  must  be
88              owned  by  root  and  not  readable by other users or it will be
89              rejected. The rule file may have comments embedded  by  starting
90              the  line  with a '#' character. Rules that are read from a file
91              are identical to what you would type on a  command  line  except
92              they  are  not  preceded  by auditctl (since auditctl is the one
93              executing the file) and you would not use shell  escaping  since
94              auditctl is reading the file instead of bash.
95
96       -t     Trim the subtrees after a mount command.
97

STATUS OPTIONS

99       -l     List all rules 1 per line. Two more options may be given to this
100              command. You can give either a key option  (-k)  to  list  rules
101              that  match a key or a (-i) to have a0 through a3 interpreted to
102              help determine the syscall argument values are correct .
103
104       -m text
105              Send a user space message into the audit system. This  can  only
106              be  done  if  you  have CAP_AUDIT_WRITE capability (normally the
107              root user has this). The resulting event will be the USER type.
108
109       -s     Report the kernel's audit subsystem status. It will tell you the
110              in-kernel  values that can be set by -e, -f, -r, and -b options.
111              The pid value is the process number of the  audit  daemon.  Note
112              that  a pid of 0 indicates that the audit daemon is not running.
113              The lost entry will tell you how many event  records  that  have
114              been  discarded  due  to the kernel audit queue overflowing. The
115              backlog field tells how many event records are currently  queued
116              waiting  for auditd to read them. This option can be followed by
117              the -i to get a couple fields interpreted.
118
119       -v     Print the version of auditctl.
120
121

RULE OPTIONS

123       -a [list,action|action,list]
124              Append rule to the end of list  with  action.  Please  note  the
125              comma  separating the two values. Omitting it will cause errors.
126              The fields may be in either order. It could  be  list,action  or
127              action,list. The following describes the valid list names:
128
129              task        Add  a  rule to the per task list. This rule list is
130                          used only at the time a  task  is  created  --  when
131                          fork()  or  clone()  are  called by the parent task.
132                          When using this list, you  should  only  use  fields
133                          that  are  known  at task creation time, such as the
134                          uid, gid, etc.
135
136              exit        Add a rule to the syscall exit list.  This  list  is
137                          used upon exit from a system call to determine if an
138                          audit event should be created.
139
140              user        Add a rule to the user  message  filter  list.  This
141                          list  is  used by the kernel to filter events origi‐
142                          nating in user space before  relaying  them  to  the
143                          audit  daemon.  It  should  be  noted  that the only
144                          fields that are valid  are:  uid,  auid,  gid,  pid,
145                          subj_user, subj_role, subj_type, subj_sen, subj_clr,
146                          and msgtype. All other fields  will  be  treated  as
147                          non-matching. It should be understood that any event
148                          originating from user space from a process that  has
149                          CAP_AUDIT_WRITE  will  be  recorded  into  the audit
150                          trail. This means that the most likely use for  this
151                          filter  is  with  rules that have an action of never
152                          since nothing has to be done to allow events  to  be
153                          recorded.
154
155              exclude     Add  a rule to the event type exclusion filter list.
156                          This list is used to filter events that you  do  not
157                          want  to see. For example, if you do not want to see
158                          any avc messages,  you  would  using  this  list  to
159                          record  that.  Events can be excluded by process ID,
160                          user ID, group ID, login user ID,  message  type  or
161                          subject context.  The action is ignored and uses its
162                          default of "never".
163
164       The following describes the valid actions for the rule:
165
166              never       No audit records will be generated. This can be used
167                          to  suppress  event generation. In general, you want
168                          suppressions at the top of the list instead  of  the
169                          bottom.  This  is  because the event triggers on the
170                          first matching rule.
171
172              always      Allocate an audit context,  always  fill  it  in  at
173                          syscall entry time, and always write out a record at
174                          syscall exit time.
175
176       -A list,action
177              Add rule to the beginning list with action.
178
179       -C [f=f | f!=f]
180              Build an inter-field comparison rule: field,  operation,  field.
181              You may pass multiple comparisons on a single command line. Each
182              one must start with -C. Each inter-field equation is anded  with
183              each  other  as well as equations starting with -F to trigger an
184              audit record. There are 2 operators supported - equal,  and  not
185              equal. Valid fields are:
186
187              auid,  uid,  euid,  suid,  fsuid,  obj_uid; and gid, egid, sgid,
188              fsgid, obj_gid
189
190              The two groups of uid and gid cannot be mixed. But any  compari‐
191              son  within  the  group  can be made. The obj_uid/gid fields are
192              collected from the object of the event such as a file or  direc‐
193              tory.
194
195
196       -d list,action
197              Delete  rule  from list with action. The rule is deleted only if
198              it exactly matches syscall name(s)  and  every  field  name  and
199              value.
200
201       -F [n=v | n!=v | n<v | n>v | n<=v | n>=v | n&v | n&=v]
202              Build  a  rule field: name, operation, value. You may have up to
203              64 fields passed on a single command line. Each one  must  start
204              with  -F.  Each field equation is anded with each other (as well
205              as equations starting with -C) to trigger an audit record. There
206              are 8 operators supported - equal, not equal, less than, greater
207              than, less than or equal, and greater than or equal,  bit  mask,
208              and  bit  test  respectively. Bit test will "and" the values and
209              check that they are equal, bit  mask  just  "ands"  the  values.
210              Fields that take a user ID may instead have the user's name; the
211              program will convert the name to user ID. The same  is  true  of
212              group names. Valid fields are:
213
214              a0, a1, a2, a3
215                          Respectively,  the  first  4 arguments to a syscall.
216                          Note that string arguments are not  supported.  This
217                          is  because  the  kernel  is passed a pointer to the
218                          string. Triggering on a pointer address value is not
219                          likely to work. So, when using this, you should only
220                          use on numeric values. This is  most  likely  to  be
221                          used on platforms that multiplex socket or IPC oper‐
222                          ations.
223
224              arch        The CPU architecture of the syscall. The arch can be
225                          found  doing 'uname -m'. If you do not know the arch
226                          of your machine but you  want  to  use  the  32  bit
227                          syscall  table and your machine supports 32 bit, you
228                          can also use b32 for the arch. The same  applies  to
229                          the  64 bit syscall table, you can use b64.  In this
230                          way, you can write  rules  that  are  somewhat  arch
231                          independent  because  the  family  type will be auto
232                          detected. However, syscalls can be arch specific and
233                          what is available on x86_64, may not be available on
234                          ppc. The arch directive should precede the -S option
235                          so  that  auditctl knows which internal table to use
236                          to look up the syscall numbers.
237
238              auid        The original ID the user  logged  in  with.  Its  an
239                          abbreviation of audit uid. Sometimes its referred to
240                          as loginuid. Either the user account text or  number
241                          may be used.
242
243              devmajor    Device Major Number
244
245              devminor    Device Minor Number
246
247              dir         Full  Path  of Directory to watch. This will place a
248                          recursive watch on the directory and its whole  sub‐
249                          tree. It can only be used on exit list. See "-w".
250
251              egid        Effective  Group  ID.  May  be numeric or the groups
252                          name.
253
254              euid        Effective User  ID.  May  be  numeric  or  the  user
255                          account name.
256
257              exe         Absolute  path  to  application that while executing
258                          this rule will apply to. This can only  be  used  on
259                          the  exit list. It supports = and != operators. Note
260                          that you can only use this once for each rule.
261
262              exit        Exit value from a syscall. If the exit  code  is  an
263                          errno, you may use the text representation, too.
264
265              fsgid       Filesystem  Group  ID.  May be numeric or the groups
266                          name.
267
268              fsuid       Filesystem User ID.  May  be  numeric  or  the  user
269                          account name.
270
271              filetype    The  target  file's  type.  Can be either file, dir,
272                          socket, link, character, block, or fifo.
273
274              gid         Group ID. May be numeric or the groups name.
275
276              inode       Inode Number
277
278              key         This is another way of setting  a  filter  key.  See
279                          discussion above for -k option.
280
281              msgtype     This  is  used  to match the event's record type. It
282                          should only be used on the exclude  or  user  filter
283                          lists.
284
285              obj_uid     Object's UID
286
287              obj_gid     Object's GID
288
289              obj_user    Resource's SE Linux User
290
291              obj_role    Resource's SE Linux Role
292
293              obj_type    Resource's SE Linux Type
294
295              obj_lev_low Resource's SE Linux Low Level
296
297              obj_lev_high
298                          Resource's SE Linux High Level
299
300              path        Full  Path  of File to watch. It can only be used on
301                          exit list.
302
303              perm        Permission filter for file operations. See "-p".  It
304                          can  only  be  used  on  exit list. You can use this
305                          without specifying a syscall  and  the  kernel  will
306                          select  the  syscalls  that  satisfy the permissions
307                          being requested.
308
309              pers        OS Personality Number
310
311              pid         Process ID
312
313              ppid        Parent's Process ID
314
315              sessionid   User's login session ID
316
317              subj_user   Program's SE Linux User
318
319              subj_role   Program's SE Linux Role
320
321              subj_type   Program's SE Linux Type
322
323              subj_sen    Program's SE Linux Sensitivity
324
325              subj_clr    Program's SE Linux Clearance
326
327              sgid        Saved Group ID. See getresgid(2) man page.
328
329              success     If the exit value is >= 0 this is true/yes otherwise
330                          its  false/no.  When  writing  a  rule,  use a 1 for
331                          true/yes and a 0 for false/no
332
333              suid        Saved User ID. See getresuid(2) man page.
334
335              uid         User ID. May be numeric or the user account name.
336
337       -k key Set a filter key on an audit rule. The filter key  is  an  arbi‐
338              trary  string  of  text  that can be up to 31 bytes long. It can
339              uniquely identify the audit records produced by a rule.  Typical
340              use  is  for when you have several rules that together satisfy a
341              security requirement. The key value  can  be  searched  on  with
342              ausearch  so  that no matter which rule triggered the event, you
343              can find its results. The key can also be  used  on  delete  all
344              (-D)  and  list  rules (-l) to select rules with a specific key.
345              You may have more than one key on a rule if you want to be  able
346              to  search  logged  events  in  multiple  ways or if you have an
347              auditd plugin that uses a key to aid its analysis.
348
349       -p [r|w|x|a]
350              Describe the permission access type that  a  file  system  watch
351              will trigger on. r=read, w=write, x=execute, a=attribute change.
352              These permissions are not the  standard  file  permissions,  but
353              rather the kind of syscall that would do this kind of thing. The
354              read & write syscalls are omitted from this set since they would
355              overwhelm  the  logs.  But  rather for reads or writes, the open
356              flags are looked at to see what permission was requested.
357
358       -S [Syscall name or number|all]
359              Any syscall name or number may be used. The word 'all' may  also
360              be  used.  If the given syscall is made by a program, then start
361              an audit record. If a field rule is  given  and  no  syscall  is
362              specified, it will default to all syscalls. You may also specify
363              multiple syscalls in the same rule by using multiple -S  options
364              in  the  same  rule.  Doing  so improves performance since fewer
365              rules need to be evaluated. Alternatively, you may pass a  comma
366              separated list of syscall names. If you are on a bi-arch system,
367              like x86_64, you should be aware that auditctl simply takes  the
368              text,  looks  it  up  for the native arch (in this case b64) and
369              sends that rule to the kernel. If there are no  additional  arch
370              directives, IT WILL APPLY TO BOTH 32 & 64 BIT SYSCALLS. This can
371              have undesirable effects since there is no  guarantee  that  any
372              syscall  has  the  same number on both 32 and 64 bit interfaces.
373              You will likely want to control this and write 2 rules, one with
374              arch equal to b32 and one with b64 to make sure the kernel finds
375              the events that you intend. See the arch  field  discussion  for
376              more info.
377
378       -w path
379              Insert  a  watch  for the file system object at path. You cannot
380              insert a watch to the top level directory. This is prohibited by
381              the kernel. Wildcards are not supported either and will generate
382              a warning. The way that watches work is by  tracking  the  inode
383              internally.  If  you  place  a  watch on a file, its the same as
384              using the -F path option on a syscall rule. If you place a watch
385              on  a  directory,  its  the same as using the -F dir option on a
386              syscall rule. The -w form of writing watches  is  for  backwards
387              compatibility  and  the  syscall  based form is more expressive.
388              Unlike most syscall auditing rules, watches do not  impact  per‐
389              formance  based  on  the number of rules sent to the kernel. The
390              only valid options when using a watch are the -p and -k. If  you
391              need  to  anything  fancy like audit a specific user accessing a
392              file, then use the syscall auditing form with the  path  or  dir
393              fields.  See  the  EXAMPLES section for an example of converting
394              one form to another.
395
396       -W path
397              Remove a watch for the file system object at path. The rule must
398              match exactly. See -d discussion for more info.
399

PERFORMANCE TIPS

401       Syscall  rules get evaluated for each syscall for every program. If you
402       have 10 syscall rules, every program on your system will delay during a
403       syscall  while  the  audit system evaluates each rule. Too many syscall
404       rules will hurt performance. Try to combine as many as you can whenever
405       the filter, action, key, and fields are identical. For example:
406
407       auditctl -a always,exit -S openat -F success=0
408       auditctl -a always,exit -S truncate -F success=0
409
410       could be re-written as one rule:
411
412       auditctl -a always,exit -S openat -S truncate -F success=0
413
414       Also, try to use file system auditing wherever practical. This improves
415       performance. For example, if you were wanting  to  capture  all  failed
416       opens  &  truncates  like above, but were only concerned about files in
417       /etc and didn't care about /usr or /sbin,  its  possible  to  use  this
418       rule:
419
420       auditctl -a always,exit -S openat -S truncate -F dir=/etc -F success=0
421
422       This  will  be higher performance since the kernel will not evaluate it
423       each and every syscall. It will be handled by the  filesystem  auditing
424       code and only checked on filesystem related syscalls.
425

EXAMPLES

427       To see all syscalls made by a specific program:
428
429       auditctl -a always,exit -S all -F pid=1005
430
431       To see files opened by a specific user:
432
433       auditctl -a always,exit -S openat -F auid=510
434
435       To see unsuccessful openat calls:
436
437       auditctl -a always,exit -S openat -F success=0
438
439       To watch a file for changes (2 ways to express):
440
441       auditctl -w /etc/shadow -p wa
442       auditctl -a always,exit -F path=/etc/shadow -F perm=wa
443
444       To recursively watch a directory for changes (2 ways to express):
445
446       auditctl -w /etc/ -p wa
447       auditctl -a always,exit -F dir=/etc/ -F perm=wa
448
449       To see if an admin is accessing other user's files:
450
451       auditctl -a always,exit -F dir=/home/ -F uid=0 -C auid!=obj_uid
452
453

FILES

455       /etc/audit/audit.rules /etc/audit/audit-stop.rules
456
457

SEE ALSO

459       audit.rules(7), auditd(8).
460
461

AUTHOR

463       Steve Grubb
464
465
466
467Red Hat                            Aug 2018                       AUDITCTL:(8)
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