# auditctl

## 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 configuration, and to load
           discretionary audit rules.
    


## CONFIGURATION OPTIONS



           **-b** _backlog_
                  Set max number (limit) of outstanding audit buffers allowed
                  (Kernel Default=64) If all buffers are full, the failure
                  flag is consulted by the kernel for action.
    
           **--backlog_wait_time** _wait_time_
                  Set the time for the kernel to wait (Kernel Default 60*HZ)
                  when the backlog limit is reached before queuing more audit
                  events to be transferred to auditd. The number must be
                  greater than or equal to zero and less than 10 times the
                  default value.
    
           **--reset_backlog_wait_time_actual**
                  Reset the actual backlog wait time counter shown by the
                  status command.
    
           **-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**
                  Help
    
           **-i** When given by itself, ignore errors when reading rules from
                  a file. This causes auditctl to always return a success
                  exit code. If passed as an argument to **-s** then it gives an
                  interpretation of the numbers to human readable words if
                  possible.
    
           **--loginuid-immutable**
                  This option tells the kernel to make loginuids unchangeable
                  once they are set. Changing loginuids requires
                  CAP_AUDIT_CONTROL. So, its not something that can be done
                  by unprivileged users. Setting this makes loginuid tamper-
                  proof, but can cause some problems in certain kinds of
                  containers.
    
           **-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 automatically 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 consulted by the
                  kernel for action. The default value is **0**.
    
           **--reset-lost**
                  Reset the lost record counter shown by the status command.
    
           **-R** _file_
                  Read and execute auditctl commands from a _file_. The
                  commands are executed line-by-line, in the order that they
                  appear in the file. The file must be owned by root and not
                  readable by other users, or else it will be rejected. Empty
                  lines are skipped. Lines starting with the '#' character
                  are treated as comment lines. Each line is executed as if
                  it was provided to auditctl as command line arguments.
                  Since auditctl is the one reading the file and not a shell
                  such as bash, do not escape special shell characters. See
                  the EXAMPLES section for an example.
    
           **--signal** _signal_
                  Send a signal to the audit daemon. You must have privileges
                  to do this. Supported signals are _TERM, HUP, USR1, USR2,_
                  _CONT_
                   and user friendly versions _stop, reload, rotate, resume,_
                  _state._
    
           **-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
                  interpreted to help determine 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 capability
                  (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 following 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,
                         msgtype, and executable name. 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. Events can be excluded by process ID,
                         user ID, group ID, login user ID, message type,
                         subject context, or executable name. The action is
                         ignored and uses its default of "never".
    
                  **filesystem**
                         Add a rule that will be applied to a whole
                         filesystem. The filesystem must be identified with a
                         fstype field. Normally this filter is used to
                         exclude any events for a whole filesystem such as
                         tracefs or debugfs.
    
                  **io_uring**
                         Add a rule to the io_uring syscall filter. Rules
                         against this filter specify the syscall operation
                         using the -S syscall notion explained below. You can
                         add a key field to the rule so that it may be
                         grouped with other rules watching the same
                         underlying syscall.
    
           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 general, 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 supported. 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 numbers.
    
                  **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.
    
                  **exe** Absolute path to application that while executing
                         this rule will apply to. It supports = and !=
                         operators. Note that you can only use this once for
                         each rule.
    
                  **exit** Exit value from a syscall. If the exit code is an
                         errno, you may use the text representation, too.
    
                  **fsgid** Filesystem Group ID. May be numeric or the groups
                         name.
    
                  **fstype** File system type. This is used with the filesystem
                         rule list. The only values supported are debugfs and
                         tracefs.
    
                  **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** 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 auditd plugin that uses a key to aid
                         its analysis.
    
                  **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** 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. This can only be used on exit
                         list.
    
                  **perm** Permission filter for file operations. Supply the
                         access type that a file system watch will trigger
                         on. **r** =read, **w** =write, **x** =execute, **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. The perm field 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 access permissions being requested. This
                         also requires supplying an arch parameter before the
                         perm field. This way the kernel can better determine
                         what syscalls are needed. Not supplying an arch will
                         result in **all** system calls being subject to audit.
                         This will lower system performance.
    
                  **pers** OS Personality Number
    
                  **pid** Process ID
    
                  **ppid** Parent's Process ID
    
                  **saddr_fam**
                         Address family number as found in
                         /usr/include/bits/socket.h. For example, IPv4 would
                         be 2 and IPv6 would be 10.
    
                  **sessionid**
                         User's login session 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. This is deprecated when
                  used with watches. Convert any watches to the syscall form
                  of rules. It is still valid for use with deleting or
                  listing rules.
    
           **-p**[**r** |**w** |**x** |**a**]
                  Describe the permission access type that a file system
                  watch will trigger on. This is deprecated. Convert watches
                  to the syscall form.
    
           **-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. Alternatively, 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_
                  Place a watch on path. If the path is a file, it's almost
                  the same as using the -F path option on a syscall rule. If
                  the watch is on a directory, it's almost the same as using
                  the -F dir option on a syscall rule. The -w form of writing
                  watches is for backwards compatibility and is **deprecated**
                  **due to poor system performance.** Convert watches of this
                  form to the syscall based form. The only valid options when
                  using a watch are the -p and -k.
    
           **-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 -F arch=b64 -S openat -F success=0**
           **auditctl -a always,exit -F arch=b64 -S truncate -F success=0**
    
           could be re-written as one rule:
    
           **auditctl -a always,exit -F arch=b64 -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 -F arch=b64 -S openat,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 handled by the filesystem
           auditing code and only checked on filesystem related syscalls.
    


## EXAMPLES



           To see all syscalls made by a specific program:
    
           # By pid:
           **auditctl -a always,exit -S all -F pid=1005**
           # By executable path
           **auditctl -a always,exit -S all -F exe=/usr/bin/ls**
    
           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 # Note this slows the system**
           **auditctl -a always,exit -F arch=b64 -F path=/etc/shadow -F perm=wa**
    
           To recursively watch a directory for changes (2 ways to express):
    
           **auditctl -w /etc/ -p wa # Note this slows the system**
           **auditctl -a always,exit -F arch=b64 -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**
    
           This is an example rules file:
    
           # Remove all existing rules
           -D
           # Never record sudo invocations
           -A exclude,always -F exe=/usr/bin/sudo
    


## DISABLED BY DEFAULT



           On many systems auditd is configured to install an **-a never,task**
           rule by default. This rule causes every new process to skip all
           audit rule processing. This is usually done to avoid a small
           performance overhead imposed by syscall auditing. If you want to
           use auditd, you need to remove that rule by deleting 10-no-
           audit.rules and adding 10-base-config.rules to the audit rules
           directory.
    
           If you have defined audit rules that are not matching when they
           should, check auditctl -l to make sure there is no never,task rule
           there.
    


## FILES



           _/etc/audit/audit.rules /etc/audit/audit-stop.rules_
    


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