AUPARSE_INTERPRET_FIELD(3) Linux Audit API AUPARSE_INTERPRET_FIELD(3)NAME
auparse_interpret_field - get current field's value interpreted
SYNOPSIS
#include <auparse.h>
const char *auparse_interpret_field(auparse_state_t *au);
DESCRIPTION
auparse_interpret_field allows access to the interpreted value in the current field of the current record in the current event. The
returned value will be destroyed if you call this function again. If you need to interpret another field and keep this value, you will have
to copy it for later use.
Examples of things that could be interpreted are: uid, gid, syscall numbers, exit codes, file paths, socket addresses, permissions, modes,
and capabilities. There are likely to be more in the future. If a value cannot be interpreted, its original value is returned.
RETURN VALUE
Returns NULL if there is an error otherwise a pointer to the interpreted value.
SEE ALSO auparse_get_field_str(3).
AUTHOR
Steve Grubb
Red Hat Feb 2007 AUPARSE_INTERPRET_FIELD(3)
Check Out this Related Man Page
AUSEARCH-EXPRESSION(5) Linux Audit AUSEARCH-EXPRESSION(5)NAME
ausearch-expression - audit search expression format
OVERVIEW
This man page describes the format of "ausearch expressions". Parsing and evaluation of these expressions is provided by libauparse and is
common to applications that use this library.
LEXICAL STRUCTURE
White space (ASCII space, tab and new-line characters) between tokens is ignored. The following tokens are recognized:
Punctuation
( )
Logical operators
! && ||
Comparison operators
< <= == > >= !== i= i!= r= r!=
Unquoted strings
Any non-empty sequence of ASCII letters, digits, and the _ symbol.
Quoted strings
A sequence of characters surrounded by the " quotes. The character starts an escape sequence. The only defined escape sequences
are \ and ". The semantics of other escape sequences is undefined.
Anywhere an unquoted string is valid, a quoted string is valid as well, and vice versa. In particular, field names may be specified using
quoted strings, and field values may be specified using unquoted strings.
EXPRESSION SYNTAX
The primary expression has the following form:
field comparison-operator value
field is either a string, which specifies the first field with that name within the current audit record, or the escape character fol-
lowed by a string, which specifies a virtual field with the specified name (virtual fields are defined in a later section).
field is a string. operator specifies the comparison to perform
r= r!= Get the "raw" string of field, and compare it to value. For fields in audit records, the "raw" string is the exact string stored in
the audit record (with all escaping and unprintable character encoding left alone); applications can read the "raw" string using
auparse_get_field_str(3). Each virtual field may define a "raw" string. If field is not present or does not define a "raw" string,
the result of the comparison is false (regardless of the operator).
i= i!= Get the "interpreted" string of field, and compare it to value. For fields in audit records, the "interpreted" string is an "user-
readable" interpretation of the field value; applications can read the "interpreted" string using auparse_interpret_field(3). Each
virtual field may define an "interpreted" string. If field is not present or does not define an "interpreted" string, the result of
the comparison is false (regardless of the operator).
< <= == > >= !==
Evaluate the "value" of field, and compare it to value. A "value" may be defined for any field or virtual field, but no "value" is
currently defined for any audit record field. The rules of parsing value for comparing it with the "value" of field are specific
for each field. If field is not present, the result of the comparison is false (regardless of the operator). If field does not
define a "value", an error is reported when parsing the expression.
If E1 and E2 are valid expressions, then ! E1, E1 && E2, and E1 || E2 are valid expressions as well, with the usual C semantics and evalu-
ation priorities. Note that ! field op value is interpreted as !(field op value), not as (!field) op value.
VIRTUAL FIELDS
The following virtual fields are defined:
imestamp
The value is the timestamp of the current event. value must have the ts:seconds.milli format, where seconds and milli are decimal
numbers specifying the seconds and milliseconds part of the timestamp, respectively.
ecord_type
The value is the type of the current record. value is either the record type name, or a decimal number specifying the type.
SEMANTICS
The expression as a whole applies to a single record. The expression is true for a specified event if it is true for any record associated
with the event.
EXAMPLES
As a demonstration of the semantics of handling missing fields, the following expression is true if field is present:
(field r= "") || (field r!= "")
and the same expression surrounded by !( and ) is true if field is not present.
FUTURE DIRECTIONS
New escape sequences for quoted strings may be defined.
For currently defined virtual fields that do not define a "raw" or "interpreted" string, the definition may be added. Therefore, don't
rely on the fact that comparing the "raw" or "interpreted" string of the field with any value is false.
New formats of value constants for the imestamp virtual field may be added.
AUTHOR
Miloslav Trmac
Red Hat Feb 2008 AUSEARCH-EXPRESSION(5)