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AUDITCTL:(8)            System Administration Utilities           AUDITCTL:(8)



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

SYNOPSIS
       auditctl [options]

DESCRIPTION
       The  auditctl  program is used to configure kernel options related to auditing, to see status of the configura-
       tion, and to load discretionary audit rules.

CONFIGURATION OPTIONS
       -b backlog
              Set max number of outstanding audit buffers allowed (Kernel Default=64) If all  buffers  are  full,  the
              failure flag is consulted by the kernel for action.

       -c     Continue  loading rules in spite of an error. This summarizes the results of loading the rules. The exit
              code will not be success if any rule fails to load.

       -D     Delete all rules and watches. This can take a key option (-k), too.

       -e [0..2]
              Set enabled flag. When 0 is passed, this can be used to temporarily disable auditing. When 1  is  passed
              as  an  argument,  it will enable auditing. To lock the audit configuration so that it can't be changed,
              pass a 2 as the argument. Locking the configuration is intended to be the last  command  in  audit.rules
              for  anyone wishing this feature to be active. Any attempt to change the configuration in this mode will
              be audited and denied. The configuration can only be changed by rebooting the machine.

       -f [0..2]
              Set failure mode 0=silent 1=printk 2=panic. This option lets you determine how you want  the  kernel  to
              handle  critical  errors.  Example  conditions where this mode may have an effect includes: transmission
              errors to userspace audit daemon, backlog limit exceeded, out of kernel memory, and rate limit exceeded.
              The default value is 1. Secure environments will probably want to set this to 2.

       -h     Help

       -i     Ignore errors when reading rules from a file. This causes auditctl to always return a success exit code.

       -q mount-point,subtree
              If you have an existing directory watch and bind or move mount another subtree in the  watched  subtree,
              you need to tell the kernel to make the subtree being mounted equivalent to the directory being watched.
              If the subtree is already mounted at the time the directory watch is issued, the  subtree  is  automati-
              cally  tagged  for  watching.  Please  note  the comma separating the two values. Omitting it will cause
              errors.

       -r rate
              Set limit in messages/sec (0=none). If this rate is non-zero and is exceeded, the failure flag  is  con-
              sulted by the kernel for action. The default value is 0.

       -R file
              Read  rules  from a file. The rules must be 1 per line and in the order that they are to be executed in.
              The rule file must be owned by root and not readable by other users or it will  be  rejected.  The  rule
              file  may  have  comments embedded by starting the line with a '#' character. Rules that are read from a
              file are identical to what you would type on a command line except they are  not  preceded  by  auditctl
              (since  auditctl  is  the one executing the file) and you would not use shell escaping since auditctl is
              reading the file instead of bash.

       -t     Trim the subtrees after a mount command.

STATUS OPTIONS
       -l     List all rules 1 per line. Two more options may be given to this command. You  can  give  either  a  key
              option  (-k)  to list rules that match a key or a (-i) to have a0 through a3 interpretted to help deter-
              mine the syscall argument values are correct .

       -m text
              Send a user space message into the audit system. This can only be done if you have CAP_AUDIT_WRITE capa-
              bility (normally the root user has this). The resulting event will be the USER type.

       -s     Report the kernel's audit subsystem status. It will tell you the in-kernel values that can be set by -e,
              -f, -r, and -b options. The pid value is the process number of the audit daemon. Note that a  pid  of  0
              indicates that the audit daemon is not running. The lost entry will tell you how many event records that
              have been discarded due to the kernel audit queue overflowing. The backlog field tells  how  many  event
              records  are  currently queued waiting for auditd to read them. This option can be followed by the -i to
              get a couple fields interpreted.

       -v     Print the version of auditctl.


RULE OPTIONS
       -a [list,action|action,list]
              Append rule to the end of list with action. Please note the comma separating the two values. Omitting it
              will  cause  errors. The fields may be in either order. It could be list,action or action,list. The fol-
              lowing describes the valid list names:

              task        Add a rule to the per task list. This rule list is used only at the time a task  is  created
                          --  when  fork()  or clone() are called by the parent task. When using this list, you should
                          only use fields that are known at task creation time, such as the uid, gid, etc.

              exit        Add a rule to the syscall exit list. This list is used upon  exit  from  a  system  call  to
                          determine if an audit event should be created.

              user        Add a rule to the user message filter list. This list is used by the kernel to filter events
                          originating in user space before relaying them to the audit daemon. It should be noted  that
                          the  only  fields  that are valid are: uid, auid, gid, pid, subj_user, subj_role, subj_type,
                          subj_sen, subj_clr, and msgtype. All other fields will be treated as non-matching. It should
                          be  understood  that  any  event  originating  from  user  space  from  a  process  that has
                          CAP_AUDIT_WRITE will be recorded into the audit trail. This means that the most  likely  use
                          for  this  filter is with rules that have an action of never since nothing has to be done to
                          allow events to be recorded.

              exclude     Add a rule to the event type exclusion filter list. This list is used to filter events  that
                          you  do  not want to see. For example, if you do not want to see any avc messages, you would
                          using this list to record that. The message type that you do not wish to see is  given  with
                          the msgtype field.

       The following describes the valid actions for the rule:

              never       No  audit  records will be generated. This can be used to suppress event generation. In gen-
                          eral, you want suppressions at the top of the list instead of the bottom.  This  is  because
                          the event triggers on the first matching rule.

              always      Allocate  an  audit context, always fill it in at syscall entry time, and always write out a
                          record at syscall exit time.

       -A list,action
              Add rule to the beginning list with action.

       -C [f=f | f!=f]
              Build an inter-field comparison rule: field, operation, field. You may pass multiple  comparisons  on  a
              single  command line. Each one must start with -C. Each inter-field equation is anded with each other as
              well as equations starting with -F to trigger an audit record. There are 2 operators supported -  equal,
              and not equal. Valid fields are:

              auid, uid, euid, suid, fsuid, obj_uid; and gid, egid, sgid, fsgid, obj_gid

              The  two  groups  of  uid  and gid cannot be mixed. But any comparison within the group can be made. The
              obj_uid/gid fields are collected from the object of the event such as a file or directory.


       -d list,action
              Delete rule from list with action. The rule is deleted only if it exactly matches  syscall  name(s)  and
              every field name and value.

       -F [n=v | n!=v | n<v | n>v | n<=v | n>=v | n&v | n&=v]
              Build  a  rule  field:  name,  operation, value. You may have up to 64 fields passed on a single command
              line. Each one must start with -F. Each field equation is anded with each other (as  well  as  equations
              starting  with  -C) to trigger an audit record. There are 8 operators supported - equal, not equal, less
              than, greater than, less than or equal, and greater than or equal, bit mask, and bit test  respectively.
              Bit  test  will  "and" the values and check that they are equal, bit mask just "ands" the values. Fields
              that take a user ID may instead have the user's name; the program will convert the name to user ID.  The
              same is true of group names. Valid fields are:

              a0, a1, a2, a3
                          Respectively,  the  first  4 arguments to a syscall. Note that string arguments are not sup-
                          ported. This is because the kernel is passed a  pointer  to  the  string.  Triggering  on  a
                          pointer  address  value  is  not likely to work. So, when using this, you should only use on
                          numeric values. This is most likely to be used on platforms that  multiplex  socket  or  IPC
                          operations.

              arch        The  CPU  architecture of the syscall. The arch can be found doing 'uname -m'. If you do not
                          know the arch of your machine but you want to use the 32 bit syscall table and your  machine
                          supports  32  bit, you can also use b32 for the arch. The same applies to the 64 bit syscall
                          table, you can use b64.  In this way, you can write rules that are somewhat arch independent
                          because  the  family  type will be auto detected. However, syscalls can be arch specific and
                          what is available on x86_64, may not be available on ppc. The arch directive should  precede
                          the -S option so that auditctl knows which internal table to use to look up the syscall num-
                          bers.

              auid        The original ID the user logged in with. Its an abbreviation of  audit  uid.  Sometimes  its
                          referred to as loginuid. Either the user account text or number may be used.

              devmajor    Device Major Number

              devminor    Device Minor Number

              dir         Full  Path of Directory to watch. This will place a recursive watch on the directory and its
                          whole subtree. It can only be used on exit list. See "-w".

              egid        Effective Group ID. May be numeric or the groups name.

              euid        Effective User ID. May be numeric or the user account name.

              exit        Exit value from a syscall. If the exit code is an errno, you may use  the  text  representa-
                          tion, too.

              fsgid       Filesystem Group ID. May be numeric or the groups name.

              fsuid       Filesystem User ID. May be numeric or the user account name.

              filetype    The target file's type. Can be either file, dir, socket, link, character, block, or fifo.

              gid         Group ID. May be numeric or the groups name.

              inode       Inode Number

              key         This is another way of setting a filter key. See discussion above for -k option.

              msgtype     This is used to match the event's record type. It should only be used on the exclude or user
                          filter lists.

              obj_uid     Object's UID

              obj_gid     Object's GID

              obj_user    Resource's SE Linux User

              obj_role    Resource's SE Linux Role

              obj_type    Resource's SE Linux Type

              obj_lev_low Resource's SE Linux Low Level

              obj_lev_high
                          Resource's SE Linux High Level

              path        Full Path of File to watch. It can only be used on exit list.

              perm        Permission filter for file operations. See "-p". It can only be used on exit list.  You  can
                          use  this  without specifying a syscall and the kernel will select the syscalls that satisfy
                          the permissions being requested.

              pers        OS Personality Number

              pid         Process ID

              ppid        Parent's Process ID

              subj_user   Program's SE Linux User

              subj_role   Program's SE Linux Role

              subj_type   Program's SE Linux Type

              subj_sen    Program's SE Linux Sensitivity

              subj_clr    Program's SE Linux Clearance

              sgid        Saved Group ID. See getresgid(2) man page.

              success     If the exit value is >= 0 this is true/yes otherwise its false/no. When writing a rule,  use
                          a 1 for true/yes and a 0 for false/no

              suid        Saved User ID. See getresuid(2) man page.

              uid         User ID. May be numeric or the user account name.

       -k key Set  a  filter  key on an audit rule. The filter key is an arbitrary string of text that can be up to 31
              bytes long. It can uniquely identify the audit records produced by a rule. Typical use is for  when  you
              have  several  rules that together satisfy a security requirement. The key value can be searched on with
              ausearch so that no matter which rule triggered the event, you can find its results. The key can also be
              used  on delete all (-D) and list rules (-l) to select rules with a specific key. You may have more than
              one key on a rule if you want to be able to search logged events in multiple ways or if you have an aud-
              ispd plugin that uses a key to aid its analysis.

       -p [r|w|x|a]
              Describe  the  permission  access type that a file system watch will trigger on. r=read, w=write, x=exe-
              cute, a=attribute change. These permissions are not the standard file permissions, but rather  the  kind
              of  syscall  that would do this kind of thing. The read & write syscalls are omitted from this set since
              they would overwhelm the logs. But rather for reads or writes, the open flags are looked at to see  what
              permission was requested.

       -S [Syscall name or number|all]
              Any  syscall  name or number may be used. The word 'all' may also be used.  If the given syscall is made
              by a program, then start an audit record. If a field rule is given and no syscall is specified, it  will
              default  to  all  syscalls. You may also specify multiple syscalls in the same rule by using multiple -S
              options in the same rule. Doing so improves performance since fewer rules need to be evaluated. Alterna-
              tively,  you  may  pass  a  comma  separated list of syscall names. If you are on a bi-arch system, like
              x86_64, you should be aware that auditctl simply takes the text, looks it up for  the  native  arch  (in
              this  case  b64)  and sends that rule to the kernel. If there are no additional arch directives, IT WILL
              APPLY TO BOTH 32 & 64 BIT SYSCALLS. This can have undesirable effects since there is no  guarantee  that
              any  syscall  has the same number on both 32 and 64 bit interfaces. You will likely want to control this
              and write 2 rules, one with arch equal to b32 and one with b64 to make sure the kernel finds the  events
              that you intend. See the arch field discussion for more info.

       -w path
              Insert a watch for the file system object at path. You cannot insert a watch to the top level directory.
              This is prohibited by the kernel. Wildcards are not supported either and will generate  a  warning.  The
              way  that watches work is by tracking the inode internally. If you place a watch on a file, its the same
              as using the -F path option on a syscall rule. If you place a watch on a  directory,  its  the  same  as
              using the -F dir option on a syscall rule. The -w form of writing watches is for backwards compatibility
              and the syscall based form is more expressive. Unlike most syscall auditing rules, watches do not impact
              performance  based  on the number of rules sent to the kernel. The only valid options when using a watch
              are the -p and -k. If you need to anything fancy like audit a specific user accessing a file,  then  use
              the  syscall  auditing form with the path or dir fields. See the EXAMPLES section for an example of con-
              verting one form to another.

       -W path
              Remove a watch for the file system object at path. The rule must match exactly. See  -d  discussion  for
              more info.

PERFORMANCE TIPS
       Syscall  rules get evaluated for each syscall for every program. If you have 10 syscall rules, every program on
       your system will delay during a syscall while the audit system evaluates each rule. Too many syscall rules will
       hurt performance. Try to combine as many as you can whenever the filter, action, key, and fields are identical.
       For example:

       auditctl -a always,exit -S openat -F success=0
       auditctl -a always,exit -S truncate -F success=0

       could be re-written as one rule:

       auditctl -a always,exit -S openat -S truncate -F success=0

       Also, try to use file system auditing wherever practical. This improves performance. For example, if  you  were
       wanting  to  capture  all  failed opens & truncates like above, but were only concerned about files in /etc and
       didn't care about /usr or /sbin, its possible to use this rule:

       auditctl -a always,exit -S openat -S truncate -F dir=/etc -F success=0

       This will be higher performance since the kernel will not evaluate it each and every syscall. It will  be  han-
       dled by the filesystem auditing code and only checked on filesystem related syscalls.

EXAMPLES
       To see all syscalls made by a specific program:

       auditctl -a always,exit -S all -F pid=1005

       To see files opened by a specific user:

       auditctl -a always,exit -S openat -F auid=510

       To see unsuccessful openat calls:

       auditctl -a always,exit -S openat -F success=0

       To watch a file for changes (2 ways to express):

       auditctl -w /etc/shadow -p wa
       auditctl -a always,exit -F path=/etc/shadow -F perm=wa

       To recursively watch a directory for changes (2 ways to express):

       auditctl -w /etc/ -p wa
       auditctl -a always,exit -F dir=/etc/ -F perm=wa

       To see if an admin is accessing other user's files:

       auditctl -a always,exit -F dir=/home/ -F uid=0 -C auid!=obj_uid


FILES
       /etc/audit/audit.rules


SEE ALSO
       audit.rules(7), auditd(8).


AUTHOR
       Steve Grubb



Red Hat                            Aug 2014                       AUDITCTL:(8)