AUDIT.LOG(5) BSD 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 path-
name 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 lengh 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 ver-
sion 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 2 bytes 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 2 bytes 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 multipled 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 1 byte 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 infor-
mation 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 indi-
cating 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
Sequnce number 4 bytes Sequnce number
Key 4 bytes IPC key
Arg Token
The ``arg'' token contains informations 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 informations about arguements 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 eviroment 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
XXXXX
Use-of-auth Token
The ``use-of-auth'' token ...
Field Bytes Description
Token ID 1 byte Token ID
XXXXX
Command Token
The ``command'' token ...
Field Bytes Description
Token ID 1 byte Token ID
XXXXX
ACL Token
The ``ACL'' token ...
Field Bytes Description
Token ID 1 byte Token ID
XXXXX
Zonename Token
The ``zonename'' token holds a NUL-terminated string with the name of the zone or jail from which the record originated. A token can be cre-
ated 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).
BSD
November 5, 2006 BSD