1AUDITCTL:(8) System Administration Utilities AUDITCTL:(8)
2
6 auditctl - a utility to assist controlling the kernel's audit system
7
9 auditctl [options]
10
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
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 -c Continue loading rules in spite of an error. This summarizes the
23 results of loading the rules. The exit code will not be success
24 if any rule fails to load.
25 -D Delete all rules and watches. This can take a key option (-k),
27 too.
28 -e [0..2]
30 Set enabled flag. When 0 is passed, this can be used to tempo‐
31 rarily disable auditing. When 1 is passed as an argument, it
32 will enable auditing. To lock the audit configuration so that it
33 can't be changed, pass a 2 as the argument. Locking the configu‐
34 ration is intended to be the last command in audit.rules for
35 anyone wishing this feature to be active. Any attempt to change
36 the configuration in this mode will be audited and denied. The
37 configuration can only be changed by rebooting the machine.
38 -f [0..2]
40 Set failure mode 0=silent 1=printk 2=panic. This option lets you
41 determine how you want the kernel to handle critical errors.
42 Example conditions where this mode may have an effect includes:
43 transmission errors to userspace audit daemon, backlog limit
44 exceeded, out of kernel memory, and rate limit exceeded. The
45 default value is 1. Secure environments will probably want to
46 set this to 2.
47 -h Help
49 -i Ignore errors when reading rules from a file. This causes
51 auditctl to always return a success exit code.
52 -q mount-point,subtree
54 If you have an existing directory watch and bind or move mount
55 another subtree in the watched subtree, you need to tell the
56 kernel to make the subtree being mounted equivalent to the
57 directory being watched. If the subtree is already mounted at
58 the time the directory watch is issued, the subtree is automati‐
59 cally tagged for watching. Please note the comma separating the
60 two values. Omitting it will cause errors.
61 -r rate
63 Set limit in messages/sec (0=none). If this rate is non-zero and
64 is exceeded, the failure flag is consulted by the kernel for
65 action. The default value is 0.
66 -R file
68 Read rules from a file. The rules must be 1 per line and in the
69 order that they are to be executed in. The rule file must be
70 owned by root and not readable by other users or it will be
71 rejected. The rule file may have comments embedded by starting
72 the line with a '#' character. Rules that are read from a file
73 are identical to what you would type on a command line except
74 they are not preceded by auditctl (since auditctl is the one
75 executing the file) and you would not use shell escaping since
76 auditctl is reading the file instead of bash.
77 -t Trim the subtrees after a mount command.
79
81 -l List all rules 1 per line. Two more options may be given to this
82 command. You can give either a key option (-k) to list rules
83 that match a key or a (-i) to have a0 through a3 interpretted to
84 help determine the syscall argument values are correct .
85 -m text
87 Send a user space message into the audit system. This can only
88 be done if you have CAP_AUDIT_WRITE capability (normally the
89 root user has this). The resulting event will be the USER type.
90 -s Report the kernel's audit subsystem status. It will tell you the
92 in-kernel values that can be set by -e, -f, -r, and -b options.
93 The pid value is the process number of the audit daemon. Note
94 that a pid of 0 indicates that the audit daemon is not running.
95 The lost entry will tell you how many event records that have
96 been discarded due to the kernel audit queue overflowing. The
97 backlog field tells how many event records are currently queued
98 waiting for auditd to read them. This option can be followed by
99 the -i to get a couple fields interpreted.
100 -v Print the version of auditctl.
102
105 -a [list,action|action,list]
106 Append rule to the end of list with action. Please note the
107 comma separating the two values. Omitting it will cause errors.
108 The fields may be in either order. It could be list,action or
109 action,list. The following describes the valid list names:
110 task Add a rule to the per task list. This rule list is
112 used only at the time a task is created -- when
113 fork() or clone() are called by the parent task.
114 When using this list, you should only use fields
115 that are known at task creation time, such as the
116 uid, gid, etc.
117 exit Add a rule to the syscall exit list. This list is
119 used upon exit from a system call to determine if an
120 audit event should be created.
121 user Add a rule to the user message filter list. This
123 list is used by the kernel to filter events origi‐
124 nating in user space before relaying them to the
125 audit daemon. It should be noted that the only
126 fields that are valid are: uid, auid, gid, pid,
127 subj_user, subj_role, subj_type, subj_sen, subj_clr,
128 and msgtype. All other fields will be treated as
129 non-matching. It should be understood that any event
130 originating from user space from a process that has
131 CAP_AUDIT_WRITE will be recorded into the audit
132 trail. This means that the most likely use for this
133 filter is with rules that have an action of never
134 since nothing has to be done to allow events to be
135 recorded.
136 exclude Add a rule to the event type exclusion filter list.
138 This list is used to filter events that you do not
139 want to see. For example, if you do not want to see
140 any avc messages, you would using this list to
141 record that. The message type that you do not wish
142 to see is given with the msgtype field.
143 The following describes the valid actions for the rule:
145 never No audit records will be generated. This can be used
147 to suppress event generation. In general, you want
148 suppressions at the top of the list instead of the
149 bottom. This is because the event triggers on the
150 first matching rule.
151 always Allocate an audit context, always fill it in at
153 syscall entry time, and always write out a record at
154 syscall exit time.
155 -A list,action
157 Add rule to the beginning list with action.
158 -C [f=f | f!=f]
160 Build an inter-field comparison rule: field, operation, field.
161 You may pass multiple comparisons on a single command line. Each
162 one must start with -C. Each inter-field equation is anded with
163 each other as well as equations starting with -F to trigger an
164 audit record. There are 2 operators supported - equal, and not
165 equal. Valid fields are:
166 auid, uid, euid, suid, fsuid, obj_uid; and gid, egid, sgid,
168 fsgid, obj_gid
169 The two groups of uid and gid cannot be mixed. But any compari‐
171 son within the group can be made. The obj_uid/gid fields are
172 collected from the object of the event such as a file or direc‐
173 tory.
174 -d list,action
177 Delete rule from list with action. The rule is deleted only if
178 it exactly matches syscall name(s) and every field name and
179 value.
180 -F [n=v | n!=v | n<v | n>v | n<=v | n>=v | n&v | n&=v]
182 Build a rule field: name, operation, value. You may have up to
183 64 fields passed on a single command line. Each one must start
184 with -F. Each field equation is anded with each other (as well
185 as equations starting with -C) to trigger an audit record. There
186 are 8 operators supported - equal, not equal, less than, greater
187 than, less than or equal, and greater than or equal, bit mask,
188 and bit test respectively. Bit test will "and" the values and
189 check that they are equal, bit mask just "ands" the values.
190 Fields that take a user ID may instead have the user's name; the
191 program will convert the name to user ID. The same is true of
192 group names. Valid fields are:
193 a0, a1, a2, a3
195 Respectively, the first 4 arguments to a syscall.
196 Note that string arguments are not supported. This
197 is because the kernel is passed a pointer to the
198 string. Triggering on a pointer address value is not
199 likely to work. So, when using this, you should only
200 use on numeric values. This is most likely to be
201 used on platforms that multiplex socket or IPC oper‐
202 ations.
203 arch The CPU architecture of the syscall. The arch can be
205 found doing 'uname -m'. If you do not know the arch
206 of your machine but you want to use the 32 bit
207 syscall table and your machine supports 32 bit, you
208 can also use b32 for the arch. The same applies to
209 the 64 bit syscall table, you can use b64. In this
210 way, you can write rules that are somewhat arch
211 independent because the family type will be auto
212 detected. However, syscalls can be arch specific and
213 what is available on x86_64, may not be available on
214 ppc. The arch directive should precede the -S option
215 so that auditctl knows which internal table to use
216 to look up the syscall numbers.
217 auid The original ID the user logged in with. Its an
219 abbreviation of audit uid. Sometimes its referred to
220 as loginuid. Either the user account text or number
221 may be used.
222 devmajor Device Major Number
224 devminor Device Minor Number
226 dir Full Path of Directory to watch. This will place a
228 recursive watch on the directory and its whole sub‐
229 tree. It can only be used on exit list. See "-w".
230 egid Effective Group ID. May be numeric or the groups
232 name.
233 euid Effective User ID. May be numeric or the user
235 account name.
236 exit Exit value from a syscall. If the exit code is an
238 errno, you may use the text representation, too.
239 fsgid Filesystem Group ID. May be numeric or the groups
241 name.
242 fsuid Filesystem User ID. May be numeric or the user
244 account name.
245 filetype The target file's type. Can be either file, dir,
247 socket, link, character, block, or fifo.
248 gid Group ID. May be numeric or the groups name.
250 inode Inode Number
252 key This is another way of setting a filter key. See
254 discussion above for -k option.
255 msgtype This is used to match the event's record type. It
257 should only be used on the exclude or user filter
258 lists.
259 obj_uid Object's UID
261 obj_gid Object's GID
263 obj_user Resource's SE Linux User
265 obj_role Resource's SE Linux Role
267 obj_type Resource's SE Linux Type
269 obj_lev_low Resource's SE Linux Low Level
271 obj_lev_high
273 Resource's SE Linux High Level
274 path Full Path of File to watch. It can only be used on
276 exit list.
277 perm Permission filter for file operations. See "-p". It
279 can only be used on exit list. You can use this
280 without specifying a syscall and the kernel will
281 select the syscalls that satisfy the permissions
282 being requested.
283 pers OS Personality Number
285 pid Process ID
287 ppid Parent's Process ID
289 subj_user Program's SE Linux User
291 subj_role Program's SE Linux Role
293 subj_type Program's SE Linux Type
295 subj_sen Program's SE Linux Sensitivity
297 subj_clr Program's SE Linux Clearance
299 sgid Saved Group ID. See getresgid(2) man page.
301 success If the exit value is >= 0 this is true/yes otherwise
303 its false/no. When writing a rule, use a 1 for
304 true/yes and a 0 for false/no
305 suid Saved User ID. See getresuid(2) man page.
307 uid User ID. May be numeric or the user account name.
309 -k key Set a filter key on an audit rule. The filter key is an arbi‐
311 trary string of text that can be up to 31 bytes long. It can
312 uniquely identify the audit records produced by a rule. Typical
313 use is for when you have several rules that together satisfy a
314 security requirement. The key value can be searched on with
315 ausearch so that no matter which rule triggered the event, you
316 can find its results. The key can also be used on delete all
317 (-D) and list rules (-l) to select rules with a specific key.
318 You may have more than one key on a rule if you want to be able
319 to search logged events in multiple ways or if you have an aud‐
320 ispd plugin that uses a key to aid its analysis.
321 -p [r|w|x|a]
323 Describe the permission access type that a file system watch
324 will trigger on. r=read, w=write, x=execute, a=attribute change.
325 These permissions are not the standard file permissions, but
326 rather the kind of syscall that would do this kind of thing. The
327 read & write syscalls are omitted from this set since they would
328 overwhelm the logs. But rather for reads or writes, the open
329 flags are looked at to see what permission was requested.
330 -S [Syscall name or number|all]
332 Any syscall name or number may be used. The word 'all' may also
333 be used. If the given syscall is made by a program, then start
334 an audit record. If a field rule is given and no syscall is
335 specified, it will default to all syscalls. You may also specify
336 multiple syscalls in the same rule by using multiple -S options
337 in the same rule. Doing so improves performance since fewer
338 rules need to be evaluated. Alternatively, you may pass a comma
339 separated list of syscall names. If you are on a bi-arch system,
340 like x86_64, you should be aware that auditctl simply takes the
341 text, looks it up for the native arch (in this case b64) and
342 sends that rule to the kernel. If there are no additional arch
343 directives, IT WILL APPLY TO BOTH 32 & 64 BIT SYSCALLS. This can
344 have undesirable effects since there is no guarantee that any
345 syscall has the same number on both 32 and 64 bit interfaces.
346 You will likely want to control this and write 2 rules, one with
347 arch equal to b32 and one with b64 to make sure the kernel finds
348 the events that you intend. See the arch field discussion for
349 more info.
350 -w path
352 Insert a watch for the file system object at path. You cannot
353 insert a watch to the top level directory. This is prohibited by
354 the kernel. Wildcards are not supported either and will generate
355 a warning. The way that watches work is by tracking the inode
356 internally. If you place a watch on a file, its the same as
357 using the -F path option on a syscall rule. If you place a watch
358 on a directory, its the same as using the -F dir option on a
359 syscall rule. The -w form of writing watches is for backwards
360 compatibility and the syscall based form is more expressive.
361 Unlike most syscall auditing rules, watches do not impact per‐
362 formance based on the number of rules sent to the kernel. The
363 only valid options when using a watch are the -p and -k. If you
364 need to anything fancy like audit a specific user accessing a
365 file, then use the syscall auditing form with the path or dir
366 fields. See the EXAMPLES section for an example of converting
367 one form to another.
368 -W path
370 Remove a watch for the file system object at path. The rule must
371 match exactly. See -d discussion for more info.
372
374 Syscall rules get evaluated for each syscall for every program. If you
375 have 10 syscall rules, every program on your system will delay during a
376 syscall while the audit system evaluates each rule. Too many syscall
377 rules will hurt performance. Try to combine as many as you can whenever
378 the filter, action, key, and fields are identical. For example:
379 auditctl -a always,exit -S openat -F success=0
381 auditctl -a always,exit -S truncate -F success=0
382 could be re-written as one rule:
384 auditctl -a always,exit -S openat -S truncate -F success=0
386 Also, try to use file system auditing wherever practical. This improves
388 performance. For example, if you were wanting to capture all failed
389 opens & truncates like above, but were only concerned about files in
390 /etc and didn't care about /usr or /sbin, its possible to use this
391 rule:
392 auditctl -a always,exit -S openat -S truncate -F dir=/etc -F success=0
394 This will be higher performance since the kernel will not evaluate it
396 each and every syscall. It will be handled by the filesystem auditing
397 code and only checked on filesystem related syscalls.
398
400 To see all syscalls made by a specific program:
401 auditctl -a always,exit -S all -F pid=1005
403 To see files opened by a specific user:
405 auditctl -a always,exit -S openat -F auid=510
407 To see unsuccessful openat calls:
409 auditctl -a always,exit -S openat -F success=0
411 To watch a file for changes (2 ways to express):
413 auditctl -w /etc/shadow -p wa
415 auditctl -a always,exit -F path=/etc/shadow -F perm=wa
416 To recursively watch a directory for changes (2 ways to express):
418 auditctl -w /etc/ -p wa
420 auditctl -a always,exit -F dir=/etc/ -F perm=wa
421 To see if an admin is accessing other user's files:
423 auditctl -a always,exit -F dir=/home/ -F uid=0 -C auid!=obj_uid
425
428 /etc/audit/audit.rules
429
432 audit.rules(7), auditd(8).
433
436 Steve Grubb
437Red Hat Aug 2014 AUDITCTL:(8)