5e386598a6
- Add a new "qsize" parameter in audit_control and the getacqsize(3) API to query it, allowing to set the kernel's maximum audit queue length. - Add support to push a mapping between audit event names and event numbers into the kernel (where supported) using new A_GETEVENT and A_SETEVENT auditon(2) operations. - Add audit event identifiers for a number of new (and not-so-new) FreeBSD system calls including those for asynchronous I/O, thread management, SCTP, jails, multi-FIB support, and misc. POSIX interfaces such as posix_fallocate(2) and posix_fadvise(2). - On operating systems supporting Capsicum, auditreduce(1) and praudit(1) now run sandboxed. - Empty "flags" and "naflags" fields are now permitted in audit_control(5). Many thanks to Christian Brueffer for producing the OpenBSM release and importing/tagging it in the vendor branch. This release will allow improved auditing of a range of new FreeBSD functionality, as well as non-traditional events (e.g., fine-grained I/O auditing) not required by the Orange Book or Common Criteria. Obtained from: TrustedBSD Project Sponsored by: DARPA, AFRL MFC after: 3 weeks
315 lines
11 KiB
Groff
315 lines
11 KiB
Groff
.\" Copyright (c) 2004-2009 Apple Inc.
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.\" Copyright (c) 2006, 2016 Robert N. M. Watson
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.\" All rights reserved.
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.\"
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.\" Portions of this software were developed by BAE Systems, the University of
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.\" Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
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.\" contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
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.\" Computing (TC) research program.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of Apple Inc. ("Apple") nor the names of
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.\" its contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR
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.\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd August 19, 2016
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.Dt AUDIT_CONTROL 5
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.Os
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.Sh NAME
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.Nm audit_control
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.Nd "audit system parameters"
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.Sh DESCRIPTION
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The
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.Nm
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file contains several audit system parameters.
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Each line of this file is of the form:
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.Pp
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.D1 Ar parameter Ns : Ns Ar value
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.Pp
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The parameters are:
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.Bl -tag -width indent
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.It Va dir
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The directory where audit log files are stored.
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There may be more than one of these entries.
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Changes to this entry can only be enacted by restarting the
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audit system.
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See
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.Xr audit 8
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for a description of how to restart the audit system.
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.It Va dist
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When set to
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.Va on
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or
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.Va yes ,
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.Xr auditd 8
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will be creating hardlinks to all trail files in
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.Pa /var/audit/dist
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directory.
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Those hardlinks will be consumed by the
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.Xr auditdistd 8
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daemon.
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.It Va flags
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Specifies which audit event classes are audited for all users.
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.Xr audit_user 5
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describes how to audit events for individual users.
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See the information below for the format of the audit flags.
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.It Va host
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Specify the hostname or IP address to be used when setting the local
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systems's audit host information.
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This hostname will be converted into an IP or IPv6 address and will
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be included in the header of each audit record.
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Due to the possibility of transient errors coupled with the
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security issues in the DNS protocol itself, the use of DNS
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should be avoided.
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Instead, it is strongly recommended that the hostname be
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specified in the /etc/hosts file.
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For more information see
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.Xr hosts 5 .
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.It Va naflags
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Contains the audit flags that define what classes of events are audited when
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an action cannot be attributed to a specific user.
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.It Va minfree
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The minimum free space required on the file system audit logs are being written to.
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When the free space falls below this limit a warning will be issued.
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If no value for the minimum free space is set, the default of 20 percent is
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applied by the kernel.
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.It Va policy
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A list of global audit policy flags specifying various behaviors, such as
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fail stop, auditing of paths and arguments, etc.
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.It Va filesz
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Maximum trail size in bytes; if set to a non-0 value, the audit daemon will
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rotate the audit trail file at around this size.
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Sizes less than the minimum trail size (default of 512K) will be rejected as
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invalid.
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If 0, trail files will not be automatically rotated based on file size.
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For convenience, the trail size may be expressed with suffix letters:
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B (Bytes), K (Kilobytes), M (Megabytes), or G (Gigabytes).
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For example, 2M is the same as 2097152.
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.It Va expire-after
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Specifies when audit log files will expire and be removed.
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This may be after a time period has passed since the file was last
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written to or when the aggregate of all the trail files have reached a
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specified size or a combination of both.
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If no expire-after parameter is given then audit log files will not
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expire and be removed by the audit control system.
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See the information below for the format of the expiration
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specification.
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.It Va qsize
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Specifies the maximum number of outstanding committed audit records that can
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be in the kernel's post-commit queue pending write to disk.
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If this number has been reached, user threads performing an auditable event
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will be suspended until the queue has fallen below the limit.
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Depending on the underlying kernel implementation, the number of in-flight
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records can exceed this number, as it does not constrain uncommitted records
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(e.g., those associated with incomplete auditable system calls), and may also
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exclude the set of records extracted from the queue and currently being
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prepared for or undergoing I/O.
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Other operational limits may be affected by this parameter, such as the
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minimum free space on disk required to continue system operation, estimated as
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the maximum number of allowable in-flight records multiplied by the maximum
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audit record size.
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.El
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.Sh AUDIT FLAGS
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Audit flags are a comma-delimited list of audit classes as defined in the
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.Xr audit_class 5
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file.
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Event classes may be preceded by a prefix which changes their interpretation.
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The following prefixes may be used for each class:
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.Pp
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.Bl -tag -width indent -compact -offset indent
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.It (none)
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Record both successful and failed events.
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.It Li +
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Record successful events.
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.It Li -
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Record failed events.
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.It Li ^
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Record neither successful nor failed events.
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.It Li ^+
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Do not record successful events.
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.It Li ^-
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Do not record failed events.
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.El
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.Sh AUDIT POLICY FLAGS
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The policy flags field is a comma-delimited list of policy flags from the
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following list:
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.Pp
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.Bl -tag -width ".Cm zonename" -compact -offset indent
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.It Cm cnt
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Allow processes to continue running even though events are not being audited.
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If not set, processes will be suspended when the audit store space is
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exhausted.
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Currently, this is not a recoverable state.
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.It Cm ahlt
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Fail stop the system if unable to audit an event\[em]this consists of first
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draining pending records to disk, and then halting the operating system.
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.It Cm argv
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Audit command line arguments to
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.Xr execve 2 .
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.It Cm arge
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Audit environmental variable arguments to
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.Xr execve 2 .
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.It Cm seq
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Include a unique audit sequence number token in generated audit records (not
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implemented on
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.Fx
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or Darwin).
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.It Cm group
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Include supplementary groups list in generated audit records (not implemented
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on
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.Fx
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or Darwin; supplementary groups are never included in records on
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these systems).
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.It Cm trail
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Append a trailer token to each audit record (not implemented on
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.Fx
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or
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Darwin; trailers are always included in records on these systems).
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.It Cm path
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Include secondary file paths in audit records (not implemented on
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.Fx
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or
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Darwin; secondary paths are never included in records on these systems).
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.It Cm zonename
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Include a zone ID token with each audit record (not implemented on
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.Fx
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or
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Darwin;
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.Fx
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audit records do not currently include the jail ID or name).
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.It Cm perzone
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Enable auditing for each local zone (not implemented on
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.Fx
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or Darwin; on
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.Fx ,
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audit records are collected from all jails and placed in a single
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global trail, and only limited audit controls are permitted within a jail).
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.El
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.Pp
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It is recommended that installations set the
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.Cm cnt
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flag but not
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.Cm ahlt
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flag unless it is intended that audit logs exceeding available disk space
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halt the system.
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.Sh AUDIT LOG EXPIRATION SPECIFICATION
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The expiration specification can be one value or two values with the
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logical conjunction of AND/OR between them.
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Values for the audit log file age are numbers with the following
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suffixes:
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.Pp
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.Bl -tag -width "(space) or" -compact -offset indent
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.It Li s
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Log file age in seconds.
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.It Li h
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Log file age in hours.
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.It Li d
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Log file age in days.
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.It Li y
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Log file age in years.
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.El
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.Pp
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Values for the disk space used are numbers with the following suffixes:
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.Pp
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.Bl -tag -width "(space) or" -compact -offset indent
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.It (space) or
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.It Li B
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Disk space used in Bytes.
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.It Li K
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Disk space used in Kilobytes.
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.It Li M
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Disk space used in Megabytes.
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.It Li G
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Disk space used in Gigabytes.
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.El
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.Pp
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The suffixes on the values are case sensitive.
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If both an age and disk space value are used they are separated by
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AND or OR and both values are used to determine when audit
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log files expire.
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In the case of AND, both the age and disk space conditions must be met
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before the log file is removed.
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In the case of OR, either condition may expire the log file.
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For example:
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.Bd -literal -offset indent
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expire-after: 60d AND 1G
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.Ed
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.Pp
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will expire files that are older than 60 days but only if 1
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gigabyte of disk space total is being used by the audit logs.
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.Sh DEFAULT
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The following settings appear in the default
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.Nm
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file:
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.Bd -literal -offset indent
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dir:/var/audit
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flags:lo,aa
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minfree:5
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naflags:lo,aa
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policy:cnt,argv
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filesz:2M
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expire-after:10M
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.Ed
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.Pp
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The
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.Va flags
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parameter above specifies the system-wide mask corresponding to login/logout
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as well as authentication and authorization events.
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The
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.Va policy
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parameter specifies that the system should neither fail stop nor suspend
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processes when the audit store fills and that command line arguments should
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be audited for
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.Dv AUE_EXECVE
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events.
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The trail file will be automatically rotated by the audit daemon when the
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file size reaches approximately 2MB.
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Trail files will expire when their aggregate size exceeds 10MB.
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.Sh FILES
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.Bl -tag -width ".Pa /etc/security/audit_control" -compact
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.It Pa /etc/security/audit_control
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.El
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.Sh SEE ALSO
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.Xr auditon 2 ,
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.Xr audit 4 ,
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.Xr audit_class 5 ,
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.Xr audit_event 5 ,
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.Xr audit_user 5 ,
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.Xr audit 8 ,
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.Xr auditd 8
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.Sh HISTORY
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The OpenBSM implementation was created by McAfee Research, the security
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division of McAfee Inc., under contract to Apple Computer Inc.\& in 2004.
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It was subsequently adopted by the TrustedBSD Project as the foundation for
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the OpenBSM distribution.
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.Sh AUTHORS
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.An -nosplit
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This software was created by McAfee Research, the security research division
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of McAfee, Inc., under contract to Apple Computer Inc.
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Additional authors include
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.An Wayne Salamon ,
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.An Robert Watson ,
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and SPARTA Inc.
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.Pp
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The Basic Security Module (BSM) interface to audit records and audit event
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stream format were defined by Sun Microsystems.
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