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RE: Audit Parsing Library Requirements



Another item that came up here at Tresys is the ability to do log
monitoring.  After our initial parse/search routine, we would like to be
able to check every so often to see if new messages have been generated and
then display the messages if they match our search criteria.  How do you
imagine this fitting in to the API?  Can we work this in somehow?

Kevin Carr
Tresys Technology
410.340.3092

> On Friday 10 March 2006 16:33, Steve Grubb wrote:
> > OK. I think the last round of comments was helpful.
> 
> 
> Audit Event Parsing Library Specifications
> ==========================================
> 
> Definitions
> -----------
> An audit event is all records that have the same host, timestamp, and
> serial number. Each event on a host has a unique timestamp and serial
> number. An event is composed of multiple records which have information
> about
> different aspects of an audit event. Each record is denoted by a type
> which
> indicates what fields will follow. Information in the fields are held by a
> name/value pair that contains an '=' between them. Each field is separated
> from one another by a space or comma.
> 
> 
> Ground Rules
> ------------
> All functions that begin with ausearch are related to searching for a
> subset
> of events based on certain criteria. All functions that begin with auparse
> are used to access events, records, and fields sequentially and without
> regard to any search options that may be in effect. All functions return 1
> on success and 0 on failure unless otherwise noted. Where the return type
> is
> a char pointer, NULL will indicate failure. The data structures will be
> hidden from the external application. Access to fields is a name/value
> style.
> You access the fields through functions that either return a pointer to an
> immutable, zero-terminated array of ASCII characters or integral values.
> Every
> function (except auparse_init) takes a parameter, au, which is the
> internal
> state information for the current query.
> 
> 
> Name-Value Matching Operators
> -----------------------------
> The ausearch_ functions will select records in its search results based on
> operators used for matching name/value pairs. For fields that are numeric,
> the following mathematical operators are allowed:  =,!=,>,=>,<,<=. The
> field
> is converted to a number before matching is done.
> 
> For fields that are non-numeric, the operators in use will be:
>         =       The string completely matches
>         !=      The string does not match
>         ~       A substring match is done
>         regex   Regular expression is used
> 
> 
> Functions
> ---------
> auparse_state_t - is an opaque data type used for maintaining library
> state.
> 
> typedef enum { AUSOURCE_LOGS, AUSOURCE_FILE, AUSOURCE_FILE_ARRAY,
>         AUSOURCE_BUFFER, AUSOURCE_BUFFER_ARRAY } ausource_t;
> 
> auparse_state_t *auparse_init(ausource_t source, const void *b) - allow
> init
> of library. Set data source: logs, file, null terminated array of
> filenames,
> buffer, null terminated array of addresses. The pointer 'b' is used to set
> the file name or pass the buff when those types are given.
> 
> typedef enum { AUSEARCH_STOP_EVENT, AUSEARCH_STOP_RECORD,
> AUSEARCH_STOP_FIELD } austop_t;
> 
> int ausearch_set_param(auparse_state_t *au, const char *field, const char
> *op,
>                        const char *value, austop_t where) - set search
> options. The field would be the left hand side of the audit name/value
> pairs.
> The op would be the operator described in the section above telling how to
> match. The value would be the right hand side of the audit field
> name/value
> pairs. The where parameter tells the search library where to place the
> internal cursor when a match is found. It could be on first field of first
> record, first field of record containing the match, or the field that
> matches.
> 
> int ausearch_next_event(auparse_state_t *au) - traverse to the next event
> that
> yields a match based on the given search criteria.
> 
> int auparse_next_event(auparse_state_t *au) - traverse to next event. This
> allows access to time and serial number.
> 
> typedef struct
> {
>         time_t sec;             // Event seconds
>         unsigned int milli;     // millisecond of the timestamp
>         unsigned long serial;   // Serial number of the event
>         const char *host;       // Machine's name
> } event_t;
> 
> event_t auparse_get_timestamp(auparse_state_t *au) - retrieve time stamp
> of
> current record
> time_t auparse_get_time(auparse_state_t *au) - retrieve time in seconds of
> current record
> time_t auparse_get_milli(auparse_state_t *au) - retrieve milliseconds time
> of
> current record
> unsigned long auparse_get_serial(auparse_state_t *au) - retrieve serial
> number
> of current record
> const char *auparse_get_node(auparse_state_t *au) - retrieve host (node)
> name
> of current record
> 
> int auparse_first_record(auparse_state_t *au) - set iterator to first
> record
> in current event
> 
> int auparse_next_record(auparse_state_t *au) - traverse to next record in
> event. This allows access to the event type
> 
> int auparse_get_type(auparse_state_t *au) - retrieve type of current
> record
> 
> int auparse_first_field(auparse_state_t *au) - set field pointer to first
> in
> current record
> 
> int auparse_next_field(auparse_state_t *au)  - traverse the fields in a
> record
> 
> const char *auparse_find_field(auparse_state_t *au, const char *name) -
> find a
> given field in a event or record. Name is the left hand side of the
> name/value
> pair. Returns pointer to the value as ascii text.
> 
> const char *auparse_find_field_next(auparse_state_t *au) - find the next
> occurance of that field in the same record. Returns pointer to the value
> as
> ascii text.
> 
> const char *auparse_get_field_str(auparse_state_t *au) - return current
> field
> value as a string
> 
> int auparse_get_field_int(auparse_state_t *au) -  return current field
> value
> as an int
> 
> const char *auparse_interpret_field(auparse_state_t *au) - interpret the
> current field
> 
> int auparse_destroy(auparse_state_t *au) - free all data structures and
> close
> file descriptors
> 
> 
> Code Example
> ------------
> int main(void)
> {
>         auparse_state_t *au = auparse_init(AUSOURCE_LOGS, NULL);
>         if (au == NULL)
>                 exit(1);
> 
>         if (!ausearch_set_param(au, "auid", "=", "500",
> AUSEARCH_STOP_EVENT))
>                 exit(1);
> 
>         while (ausearch_next_event(au)) {
>                 if (auparse_find_field(au, "auid")) {
>                         printf("auid=%s\n", auparse_interpret_field(au));
>                 }
>         }
>         auparse_destroy(au);
>         return 0;
> }
> 
> --
> Linux-audit mailing list
> Linux-audit redhat com
> https://www.redhat.com/mailman/listinfo/linux-audit



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