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 | 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 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 | 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 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).