AUDIT.LOG(5) FreeBSD File Formats Manual AUDIT.LOG(5)
NAME
audit - Basic Security Module (BSM) file format
DESCRIPTION
The audit file format is based on Sun's Basic Security Module (BSM) file
format, a token-based record stream to represent system audit data. This
file format is both flexible and extensible, able to describe a broad
range of data types, and easily extended to describe new data types in a
moderately backward and forward compatible way.
BSM token streams typically begin and end with a "file" token, which
provides time stamp and file name information for the stream; when
processing a BSM token stream from a stream as opposed to a single file
source, file tokens may be seen at any point between ordinary records
identifying when particular parts of the stream begin and end. All other
tokens will appear in the context of a complete BSM audit record, which
begins with a "header" token, and ends with a "trailer" token, which
describe the audit record. Between these two tokens will appear a
variety of data tokens, such as process information, file path names, IPC
object information, MAC labels, socket information, and so on.
The BSM file format defines specific token orders for each record event
type; however, some variation may occur depending on the operating system
in use, what system options, such as mandatory access control, are
present.
This manual page documents the common token types and their binary
format, and is intended for reference purposes only. It is recommended
that application programmers use the libbsm(3) interface to read and
write tokens, rather than parsing or constructing records by hand.
File Token
The "file" token is used at the beginning and end of an audit log file to
indicate when the audit log begins and ends. It includes a pathname so
that, if concatenated together, original file boundaries are still
observable, and gaps in the audit log can be identified. A "file" token
can be created using au_to_file(3).
Field Bytes Description
Token ID 1 byte Token ID
Seconds 4 bytes File time
stamp
Microseconds 4 bytes File time
stamp
File name length 2 bytes File name
of audit
trail
File pathname N bytes + 1 NUL File name
of audit
trail
Header Token
The "header" token is used to mark the beginning of a complete audit
record, and includes the length of the total record in bytes, a version
number for the record layout, the event type and subtype, and the time at
which the event occurred. A 32-bit "header" token can be created using
au_to_header32(3); a 64-bit "header" token can be created using
au_to_header64(3).
Field Bytes Description
Token ID 1 byte Token ID
Record Byte Count 4 bytes Number of
bytes in
record
Version Number 1 byte Record
version
number
Event Type 2 bytes Event type
Event Modifier 2 bytes Event
sub-type
Seconds 4/8 bytes Record time
stamp
(32/64-bits)
Nanoseconds 4/8 bytes Record time
stamp
(32/64-bits)
Expanded Header Token
The "expanded header" token is an expanded version of the "header" token,
with the addition of a machine IPv4 or IPv6 address. A 32-bit extended
"header" token can be created using au_to_header32_ex(3); a 64-bit
extended "header" token can be created using au_to_header64_ex(3).
Field Bytes Description
Token ID 1 byte Token ID
Record Byte Count 4 bytes Number of
bytes in
record
Version Number 1 byte Record
version
number
Event Type 2 bytes Event type
Event Modifier 2 bytes Event
sub-type
Address Type/Length 1 byte Host
address
type and
length
Machine Address 4/16 bytes IPv4 or
IPv6
address
Seconds 4/8 bytes Record time
stamp
(32/64-bits)
Nanoseconds 4/8 bytes Record time
stamp
(32/64-bits)
Trailer Token
The "trailer" terminates a BSM audit record, and contains a magic number,
AUT_TRAILER_MAGIC and length that can be used to validate that the record
was read properly. A "trailer" token can be created using
au_to_trailer(3).
Field Bytes Description
Token ID 1 byte Token ID
Trailer Magic 2 bytes Trailer
magic
number
Record Byte Count 4 bytes Number of
bytes in
record
Arbitrary Data Token
The "arbitrary data" token contains a byte stream of opaque (untyped)
data. The size of the data is calculated as the size of each unit of
data multiplied by the number of units of data. A "How to print" field
is present to specify how to print the data, but interpretation of that
field is not currently defined. An "arbitrary data" token can be created
using au_to_data(3).
Field Bytes Description
Token ID 1 byte Token ID
How to Print 1 byte User-defined
printing
information
Basic Unit 1 byte Size of a
unit in
bytes
Unit Count 1 byte Number of
units of
data
present
Data Items Variable User data
in_addr Token
The "in_addr" token holds a network byte order IPv4 address. An
"in_addr" token can be created using au_to_in_addr(3) for an IPv4
address.
Field Bytes Description
Token ID 1 byte Token ID
IP Address 4 bytes IPv4
address
Expanded in_addr Token
The "in_addr_ex" token holds a network byte order IPv4 or IPv6 address.
An "in_addr_ex" token can be created using au_to_in_addr_ex(3) for an
IPv6 address.
See the BUGS section for information on the storage of this token.
Field Bytes Description
Token ID 1 byte Token ID
IP Address Type 1 byte Type of
address
IP Address 4/16 bytes IPv4 or
IPv6
address
ip Token
The "ip" token contains an IP packet header in network byte order. An
"ip" token can be created using au_to_ip(3).
Field Bytes Description
Token ID 1 byte Token ID
Version and IHL 1 byte Version and
IP header
length
Type of Service 1 byte IP TOS
field
Length 2 bytes IP packet
length in
network
byte order
ID 2 bytes IP header
ID for
reassembly
Offset 2 bytes IP fragment
offset and
flags,
network
byte order
TTL 1 byte IP
Time-to-Live
Protocol 1 byte IP protocol
number
Checksum 2 bytes IP header
checksum,
network
byte order
Source Address 4 bytes IPv4 source
address
Destination Address 4 bytes IPv4
destination
address
iport Token
The "iport" token stores an IP port number in network byte order. An
"iport" token can be created using au_to_iport(3).
Field Bytes Description
Token ID 1 byte Token ID
Port Number 2 bytes Port number
in network
byte order
Path Token
The "path" token contains a pathname. A "path" token can be created
using au_to_path(3).
Field Bytes Description
Token ID 1 byte Token ID
Path Length 2 bytes Length of
path in
bytes
Path N bytes + 1 NUL Path name
path_attr Token
The "path_attr" token contains a set of NUL-terminated path names. The
libbsm(3) API cannot currently create a "path_attr" token.
Field Bytes Description
Token ID 1 byte Token ID
Count 2 bytes Number of
NUL-terminated
string(s)
in token
Path Variable count
NUL-terminated
string(s)
Process Token
The "process" token contains a description of the security properties of
a process involved as the target of an auditable event, such as the
destination for signal delivery. It should not be confused with the
"subject" token, which describes the subject performing an auditable
event. This includes both the traditional UNIX security properties, such
as user IDs and group IDs, but also audit information such as the audit
user ID and session. A "process" token can be created using
au_to_process32(3) or au_to_process64(3).
Field Bytes Description
Token ID 1 byte Token ID
Audit ID 4 bytes Audit user
ID
Effective User ID 4 bytes Effective
user ID
Effective Group ID 4 bytes Effective
group ID
Real User ID 4 bytes Real user
ID
Real Group ID 4 bytes Real group
ID
Process ID 4 bytes Process ID
Session ID 4 bytes Audit
session ID
Terminal Port ID 4/8 bytes Terminal
port ID
(32/64-bits)
Terminal Machine Address 4 bytes IP address
of machine
Expanded Process Token
The "expanded process" token contains the contents of the "process"
token, with the addition of a machine address type and variable length
address storage capable of containing IPv6 addresses. An "expanded
process" token can be created using au_to_process32_ex(3) or
au_to_process64_ex(3).
Field Bytes Description
Token ID 1 byte Token ID
Audit ID 4 bytes Audit user
ID
Effective User ID 4 bytes Effective
user ID
Effective Group ID 4 bytes Effective
group ID
Real User ID 4 bytes Real user
ID
Real Group ID 4 bytes Real group
ID
Process ID 4 bytes Process ID
Session ID 4 bytes Audit
session ID
Terminal Port ID 4/8 bytes Terminal
port ID
(32/64-bits)
Terminal Address Type/Length 4 bytes Length of
machine
address
Terminal Machine Address 4 bytes IPv4 or
IPv6
address of
machine
Return Token
The "return" token contains a system call or library function return
condition, including return value and error number associated with the
global variable errno. A "return" token can be created using
au_to_return32(3) or au_to_return64(3).
Field Bytes Description
Token ID 1 byte Token ID
Error Number 1 byte Errno
value, or 0
if
undefined
Return Value 4/8 bytes Return
value
(32/64-bits)
Subject Token
The "subject" token contains information on the subject performing the
operation described by an audit record, and includes similar information
to that found in the "process" and "expanded process" tokens. However,
those tokens are used where the process being described is the target of
the operation, not the authorizing party. A "subject" token can be
created using au_to_subject32(3) and au_to_subject64(3).
Field Bytes Description
Token ID 1 byte Token ID
Audit ID 4 bytes Audit user
ID
Effective User ID 4 bytes Effective
user ID
Effective Group ID 4 bytes Effective
group ID
Real User ID 4 bytes Real user
ID
Real Group ID 4 bytes Real group
ID
Process ID 4 bytes Process ID
Session ID 4 bytes Audit
session ID
Terminal Port ID 4/8 bytes Terminal
port ID
(32/64-bits)
Terminal Machine Address 4 bytes IP address
of machine
Expanded Subject Token
The "expanded subject" token consists of the same elements as the
"subject" token, with the addition of type/length and variable size
machine address information in the terminal ID. An "expanded subject"
token can be created using au_to_subject32_ex(3) or
au_to_subject64_ex(3).
Field Bytes Description
Token ID 1 byte Token ID
Audit ID 4 bytes Audit user
ID
Effective User ID 4 bytes Effective
user ID
Effective Group ID 4 bytes Effective
group ID
Real User ID 4 bytes Real user
ID
Real Group ID 4 bytes Real group
ID
Process ID 4 bytes Process ID
Session ID 4 bytes Audit
session ID
Terminal Port ID 4/8 bytes Terminal
port ID
(32/64-bits)
Terminal Address Type/Length 1 byte Length of
machine
address
Terminal Machine Address 4 bytes IPv4 or
IPv6
address of
machine
System V IPC Token
The "System V IPC" token contains the System V IPC message handle,
semaphore handle or shared memory handle. A System V IPC token may be
created using +.Xr au_to_ipc 3 .
Field Bytes Description
Token ID 1 byte Token ID
Object ID type 1 byte Object ID
Object ID 4 bytes Object ID
Text Token
The "text" token contains a single NUL-terminated text string. A "text"
token may be created using au_to_text(3).
Field Bytes Description
Token ID 1 byte Token ID
Text Length 2 bytes Length of
text string
including
NUL
Text N bytes + 1 NUL Text string
including
NUL
Attribute Token
The "attribute" token describes the attributes of a file associated with
the audit event. As files may be identified by 0, 1, or many path names,
a path name is not included with the attribute block for a file; optional
"path" tokens may also be present in an audit record indicating which
path, if any, was used to reach the object. An "attribute" token can be
created using au_to_attr32(3) or au_to_attr64(3).
Field Bytes Description
Token ID 1 byte Token ID
File Access Mode 1 byte mode_t
associated
with file
Owner User ID 4 bytes uid_t
associated
with file
Owner Group ID 4 bytes gid_t
associated
with file
File System ID 4 bytes fsid_t
associated
with file
File System Node ID 8 bytes ino_t
associated
with file
Device 4/8 bytes Device
major/minor
number
(32/64-bit)
Groups Token
The "groups" token contains a list of group IDs associated with the audit
event. A "groups" token can be created using au_to_groups(3).
Field Bytes Description
Token ID 1 byte Token ID
Number of Groups 2 bytes Number of
groups in
token
Group List N * 4 bytes List of N
group IDs
System V IPC Permission Token
The "System V IPC permission" token contains a System V IPC access
permissions. A System V IPC permission token may be created using
au_to_ipc_perm(3).
Field Bytes Description
Token ID 1 byte Token ID
Owner user ID 4 bytes User ID of
IPC owner
Owner group ID 4 bytes Group ID of
IPC owner
Creator user ID 4 bytes User ID of
IPC creator
Creator group ID 4 bytes Group ID of
IPC creator
Access mode 4 bytes Access mode
Sequence number 4 bytes Sequence
number
Key 4 bytes IPC key
Arg Token
The "arg" token contains information about arguments of the system call.
Depending on the size of the desired argument value, an Arg token may be
created using au_to_arg32(3) or au_to_arg64(3).
Field Bytes Description
Token ID 1 byte Token ID
Argument ID 1 byte Argument ID
Argument value 4/8 bytes Argument
value
Length 2 bytes Length of
the text
Text N bytes + 1 nul The string
including
nul
exec_args Token
The "exec_args" token contains information about arguments of the exec()
system call. An exec_args token may be created using au_to_exec_args(3).
Field Bytes Description
Token ID 1 byte Token ID
Count 4 bytes Number of
arguments
Text * bytes Count
nul-terminated
strings
exec_env Token
The "exec_env" token contains current environment variables to an exec()
system call. An exec_args token may be created using au_to_exec_env(3).
Field Bytes Description
Token ID 1 byte Token ID
Count ID 4 bytes Number of
variables
Text * bytes Count
nul-terminated
strings
Exit Token
The "exit" token contains process exit/return code information. An
"exit" token can be created using au_to_exit(3).
Field Bytes Description
Token ID 1 byte Token ID
Status 4 bytes Process
status on
exit
Return Value 4 bytes Process
return
value on
exit
Socket Token
The "socket" token contains information about UNIX domain and Internet
sockets. Each token has four or eight fields. Depending on the type of
socket, a socket token may be created using au_to_sock_unix(3),
au_to_sock_inet32(3) or au_to_sock_inet128(3).
Field Bytes Description
Token ID 1 byte Token ID
Socket family 2 bytes Socket family
Local port 2 bytes Local port
Socket address 4 bytes Socket address
Expanded Socket Token
The "expanded socket" token contains information about IPv4 and IPv6
sockets. A "expanded socket" token can be created using
au_to_socket_ex(3).
Field Bytes Description
Token ID 1 byte Token ID
Socket domain 2 bytes Socket
domain
Socket type 2 bytes Socket type
Address type 2 byte Address
type
(IPv4/IPv6)
Local port 2 bytes Local port
Local IP address 4/16 bytes Local IP
address
Remote port 2 bytes Remote port
Remote IP address 4/16 bytes Remote IP
address
Seq Token
The "seq" token contains a unique and monotonically increasing audit
event sequence ID. Due to the limited range of 32 bits, serial number
arithmetic and caution should be used when comparing sequence numbers.
Field Bytes Description
Token ID 1 byte Token ID
Sequence Number 4 bytes Audit event
sequence
number
privilege Token
The "privilege" token ...
Field Bytes Description
Token ID 1 byte Token ID
Use-of-auth Token
The "use-of-auth" token ...
Field Bytes Description
Token ID 1 byte Token ID
Command Token
The "command" token ...
Field Bytes Description
Token ID 1 byte Token ID
ACL Token
The "ACL" token ...
Field Bytes Description
Token ID 1 byte Token ID
Zonename Token
The "zonename" token holds a NUL-terminated string with the name of the
zone or jail from which the record originated. A "zonename" token can be
created using au_to_zonename(3).
Field Bytes Description
Token ID 1 byte Token ID
Zonename length 2 bytes Length of
zonename
string
including
NUL
Zonename N bytes + 1 NUL Zonename
string
including
NUL
SEE ALSO
auditreduce(1), praudit(1), libbsm(3), audit(4), auditpipe(4), audit(8)
HISTORY
The OpenBSM implementation was created by McAfee Research, the security
division of McAfee Inc., under contract to Apple Computer Inc. in 2004.
It was subsequently adopted by the TrustedBSD Project as the foundation
for the OpenBSM distribution.
AUTHORS
The Basic Security Module (BSM) interface to audit records and audit
event stream format were defined by Sun Microsystems.
This manual page was written by Robert Watson <rwatson@FreeBSD.org>.
BUGS
The "How to print" field in the "arbitrary data" token has undefined
values.
The "in_addr" and "in_addr_ex" token layout documented here appears to be
in conflict with the libbsm(3) implementation of au_to_in_addr_ex(3).
FreeBSD 13.1-RELEASE-p6 November 5, 2006 FreeBSD 13.1-RELEASE-p6
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