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 control the behavior, get status, and
13 add or delete rules into the 2.6 kernel's audit system.
14
16 -b backlog
17 Set max number of outstanding audit buffers allowed (Kernel
18 Default=64) If all buffers are full, the failure flag is con‐
19 sulted by the kernel for action.
20 -e [0..2]
22 Set enabled flag. When 0 is passed, this can be used to tempo‐
23 rarily disable auditing. When 1 is passed as an argument, it
24 will enable auditing. To lock the audit configuration so that it
25 can't be changed, pass a 2 as the argument. Locking the configu‐
26 ration is intended to be the last command in audit.rules for
27 anyone wishing this feature to be active. Any attempt to change
28 the configuration in this mode will be audited and denied. The
29 configuration can only be changed by rebooting the machine.
30 -f [0..2]
32 Set failure flag 0=silent 1=printk 2=panic. This option lets you
33 determine how you want the kernel to handle critical errors.
34 Example conditions where this flag is consulted includes: trans‐
35 mission errors to userspace audit daemon, backlog limit
36 exceeded, out of kernel memory, and rate limit exceeded. The
37 default value is 1. Secure environments will probably want to
38 set this to 2.
39 -h Help
41 -i Ignore errors when reading rules from a file
43 -l List all rules 1 per line. This can take a key option (-k), too.
45 -k key Set a filter key on an audit rule. The filter key is an arbi‐
47 trary string of text that can be up to 31 bytes long. It can
48 uniquely identify the audit records produced by a rule. Typical
49 use is for when you have several rules that together satisfy a
50 security requirement. The key value can be searched on with
51 ausearch so that no matter which rule triggered the event, you
52 can find its results. The key can also be used on delete all
53 (-D) and list rules (-l) to select rules with a specific key.
54 You may have more than one key on a rule if you want to be able
55 to search logged events in multiple ways or if you have an aud‐
56 ispd plugin that uses a key to aid its analysis.
57 -m text
59 Send a user space message into the audit system. This can only
60 be done if you have CAP_AUDIT_WRITE capability (normally the
61 root user has this). The resulting event will be the USER type.
62 -p [r|w|x|a]
64 Describe the permission access type that a file system watch
65 will trigger on. r=read, w=write, x=execute, a=attribute change.
66 These permissions are not the standard file permissions, but
67 rather the kind of syscall that would do this kind of thing. The
68 read & write syscalls are omitted from this set since they would
69 overwhelm the logs. But rather for reads or writes, the open
70 flags are looked at to see what permission was requested.
71 -q mount-point,subtree
73 If you have an existing directory watch and bind or move mount
74 another subtree in the watched subtree, you need to tell the
75 kernel to make the subtree being mounted equivalent to the
76 directory being watched. If the subtree is already mounted at
77 the time the directory watch is issued, the subtree is automati‐
78 cally tagged for watching. Please note the comma separating the
79 two values. Omitting it will cause errors.
80 -r rate
82 Set limit in messages/sec (0=none). If this rate is non-zero and
83 is exceeded, the failure flag is consulted by the kernel for
84 action. The default value is 0.
85 -R file
87 Read rules from a file. The rules must be 1 per line and in the
88 order that they are to be executed in. The rule file must be
89 owned by root and not readable by other users or it will be
90 rejected. The rule file may have comments embedded by starting
91 the line with a '#' character. Rules that are read from a file
92 are identical to what you would type on a command line except
93 they are not preceded by auditctl (since auditctl is the one
94 executing the file).
95 -s Report the kernel's audit subsystem status. It will tell you the
97 in-kernel values that can be set by -e, -f, -r, and -b options.
98 The pid value is the process number of the audit daemon. Note
99 that a pid of 0 indicates that the audit daemon is not running.
100 The lost entry will tell you how many event records that have
101 been discarded due to the kernel audit queue overflowing. The
102 backlog field tells how many event records are currently queued
103 waiting for auditd to read them.
104 -t Trim the subtrees after a mount command.
106 -a [list,action|action,list]
108 Append rule to the end of list with action. Please note the
109 comma separating the two values. Omitting it will cause errors.
110 The fields may be in either order. It could be list,action or
111 action,list. The following describes the valid list names:
112 task Add a rule to the per task list. This rule list is
114 used only at the time a task is created -- when
115 fork() or clone() are called by the parent task.
116 When using this list, you should only use fields
117 that are known at task creation time, such as the
118 uid, gid, etc.
119 exit Add a rule to the syscall exit list. This list is
121 used upon exit from a system call to determine if an
122 audit event should be created.
123 user Add a rule to the user message filter list. This
125 list is used by the kernel to filter events origi‐
126 nating in user space before relaying them to the
127 audit daemon. It should be noted that the only
128 fields that are valid are: uid, auid, gid, pid,
129 subj_user, subj_role, subj_type, subj_sen, and
130 subj_clr. All other fields will be treated as non-
131 matching.
132 exclude Add a rule to the event type exclusion filter list.
134 This list is used to filter events that you do not
135 want to see. For example, if you do not want to see
136 any avc messages, you would using this list to
137 record that. The message type that you do not wish
138 to see is given with the msgtype field.
139 The following describes the valid actions for the rule:
141 never No audit records will be generated. This can be used
143 to suppress event generation. In general, you want
144 suppressions at the top of the list instead of the
145 bottom. This is because the event triggers on the
146 first matching rule.
147 always Allocate an audit context, always fill it in at
149 syscall entry time, and always write out a record at
150 syscall exit time.
151 -A list,action
153 Add rule to the beginning list with action.
154 -d list,action
156 Delete rule from list with action. The rule is deleted only if
157 it exactly matches syscall name(s) and every field name and
158 value.
159 -D Delete all rules and watches. This can take a key option (-k),
161 too.
162 -S [Syscall name or number|all]
164 Any syscall name or number may be used. The word 'all' may also
165 be used. If the given syscall is made by a program, then start
166 an audit record. If a field rule is given and no syscall is
167 specified, it will default to all syscalls. You may also specify
168 multiple syscalls in the same rule by using multiple -S options
169 in the same rule. Doing so improves performance since fewer
170 rules need to be evaluated. If you are on a bi-arch system, like
171 x86_64, you should be aware that auditctl simply takes the text,
172 looks it up for the native arch (in this case b64) and sends
173 that rule to the kernel. If there are no additional arch direc‐
174 tives, IT WILL APPLY TO BOTH 32 & 64 BIT SYSCALLS. This can have
175 undesirable effects since there is no guarantee that, for exam‐
176 ple, the open syscall has the same number on both 32 and 64 bit
177 interfaces. You will likely want to control this and write 2
178 rules, one with arch equal to b32 and one with b64 to make sure
179 the kernel finds the events that you intend. See the arch field
180 discussion for more info.
181 -F [n=v | n!=v | n<v | n>v | n<=v | n>=v | n&v | n&=v]
183 Build a rule field: name, operation, value. You may have up to
184 64 fields passed on a single command line. Each one must start
185 with -F. Each field equation is anded with each other to trigger
186 an audit record. There are 8 operators supported - equal, not
187 equal, less than, greater than, less than or equal, and greater
188 than or equal, bit mask, and bit test respectively. Bit test
189 will "and" the values and check that they are equal, bit mask
190 just "ands" the values. Fields that take a user ID may instead
191 have the user's name; the program will convert the name to user
192 ID. The same is true of 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, symlink, char, 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 filter list.
258 obj_user Resource's SE Linux User
260 obj_role Resource's SE Linux Role
262 obj_type Resource's SE Linux Type
264 obj_lev_low Resource's SE Linux Low Level
266 obj_lev_high
268 Resource's SE Linux High Level
269 path Full Path of File to watch. It can only be used on
271 exit list.
272 perm Permission filter for file operations. See "-p". It
274 can only be used on exit list. You can use this
275 without specifying a syscall and the kernel will
276 select the syscalls that satisfy the permissions
277 being requested.
278 pers OS Personality Number
280 pid Process ID
282 ppid Parent's Process ID
284 subj_user Program's SE Linux User
286 subj_role Program's SE Linux Role
288 subj_type Program's SE Linux Type
290 subj_sen Program's SE Linux Sensitivity
292 subj_clr Program's SE Linux Clearance
294 sgid Saved Group ID. See getresgid(2) man page.
296 success If the exit value is >= 0 this is true/yes otherwise
298 its false/no. When writing a rule, use a 1 for
299 true/yes and a 0 for false/no
300 suid Saved User ID. See getresuid(2) man page.
302 uid User ID. May be numeric or the user account name.
304 -w path
306 Insert a watch for the file system object at path. You cannot
307 insert a watch to the top level directory. This is prohibited by
308 the kernel. Wildcards are not supported either and will generate
309 a warning. The way that watches work is by tracking the inode
310 internally. If you place a watch on a file, its the same as
311 using the -F path option on a syscall rule. If you place a watch
312 on a directory, its the same as using the -F dir option on a
313 syscall rule. The -w form of writing watches is for backwards
314 compatibility and the syscall based form is more expressive.
315 Unlike most syscall auditing rules, watches do not impact per‐
316 formance based on the number of rules sent to the kernel. The
317 only valid options when using a watch are the -p and -k. If you
318 need to anything fancy like audit a specific user accessing a
319 file, then use the syscall auditing form with the path or dir
320 fields. See the EXAMPLES section for an example of converting
321 one form to another.
322 -W path
324 Remove a watch for the file system object at path. The rule must
325 match exactly. See -d discussion for more info.
326
328 Syscall rules get evaluated for each syscall for every program. If you
329 have 10 syscall rules, every program on your system will delay during a
330 syscall while the audit system evaluates each rule. Too many syscall
331 rules will hurt performance. Try to combine as many as you can whenever
332 the filter, action, key, and fields are identical. For example:
333 auditctl -a exit,always -S open -F success=0
335 auditctl -a exit,always -S truncate -F success=0
336 could be re-written as one rule:
338 auditctl -a exit,always -S open -S truncate -F success=0
340 Also, try to use file system auditing wherever practical. This improves
342 performance. For example, if you were wanting to capture all failed
343 opens & truncates like above, but were only concerned about files in
344 /etc and didn't care about /usr or /sbin, its possible to use this
345 rule:
346 auditctl -a exit,always -S open -S truncate -F dir=/etc -F success=0
348 This will be higher performance since the kernel will not evaluate it
350 each and every syscall. It will be handled by the filesystem auditing
351 code and only checked on filesystem related syscalls.
352
354 To see all syscalls made by a specific program:
355 auditctl -a exit,always -S all -F pid=1005
357 To see files opened by a specific user:
359 auditctl -a exit,always -S open -F auid=510
361 To see unsuccessful open calls:
363 auditctl -a exit,always -S open -F success=0
365 To watch a file for changes (2 ways to express):
367 auditctl -w /etc/shadow -p wa
369 auditctl -a exit,always -F path=/etc/shadow -F perm=wa
370 To recursively watch a directory for changes (2 ways to express):
372 auditctl -w /etc/ -p wa
374 auditctl -a exit,always -F dir=/etc/ -F perm=wa
375
378 /etc/audit/audit.rules
379
382 audit.rules(7), auditd(8).
383
386 Steve Grubb
387Red Hat Feb 2011 AUDITCTL:(8)