AU_OPEN(3) BSD Library Functions Manual AU_OPEN(3)NAME
au_close, au_close_buffer, au_close_token, au_open, au_write — create and
commit audit records
au_write(int d, token_t *tok);
au_close(int d, int keep, short event);
au_close_buffer(int d, short event, u_char *buffer, size_t *buflen);
au_close_token(token_t *tok, u_char *buffer, size_t *buflen);
These interfaces allow applications to allocate audit records, construct
a record using a series of tokens, and commit the audit record to the
system event log. An extension API is also provided to commit the record
to an in-memory buffer rather than the system audit log.
The au_open() interface allocates a new audit record descriptor.
The au_write() interface adds a token to an allocated audit descriptor.
When a token has been successfully added to a record, the caller no
longer owns the token memory, and does not need to free it directly via a
call to au_free_token(3).
The au_close() function is used to commit an audit record to the system
audit log, or abandon the record. In either cases, all resources associ‐
ated with the record will be released. The keep argument determines the
behavior: a value of AU_TO_WRITE causes the record to be committed; a
value of AU_TO_NO_WRITE causes it to be abandoned. When the audit record
is committed, a BSM header will be inserted before tokens added to the
record, using the event identifier passed via event, and a trailer added
to the end. Committing a record to the system audit log requires privi‐
The au_close_buffer() function writes the resulting record to an in-mem‐
ory buffer of size *buflen; it will write back the filled buffer length
into the same variable. The argument event is the event identifier to
use in the record header.
The au_close_token() function generates the BSM stream output for a sin‐
gle token, tok, in the passed buffer buffer. The initial buffer size and
resulting data size are passed via *buflen. The au_close_token() func‐
tion will free the token before returning.
The function au_open() returns a non-negative audit record descriptor
number on success, or a negative value on failure, along with error
information in errno.
The functions au_write(), au_close(), au_close_buffer(), and
au_close_token() return 0 on success, or a negative value on failure,
along with error information in errno.
SEE ALSOaudit_submit(3), libbsm(3)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.
This software was created by Robert Watson, Wayne Salamon, and Suresh
Krishnaswamy for McAfee Research, the security research division of
McAfee, Inc., under contract to Apple Computer, Inc.
The Basic Security Module (BSM) interface to audit records and audit
event stream format were defined by Sun Microsystems.
Currently, au_open() does not reserve kernel resources necessary to com‐
mit the record to the trail; on systems supporting au_close(), the call
will block until resources are available to commit the record. However,
this leads to the possibility of an action being permitted without the
record being guaranteed to go to disk. Ideally, au_open() would reserve
resources necessary to commit any submitted record, releasing them on
BSD March 4, 2006 BSD