Hello Richard,

Although I have it working, I have some comments below that might improve
things.

On Tuesday, August 9, 2022 1:22:55 PM EDT Richard Guy Briggs wrote:
> Currently the only type of fanotify info that is defined is an audit
> rule number, but convert it to hex encoding to future-proof the field.
> 
> Sample record:
>   type=FANOTIFY msg=audit(1659730979.839:284): resp=1 fan_type=0
> fan_info=3F
> 
> Suggested-by: Paul Moore <p...@paul-moore.com>
> Signed-off-by: Richard Guy Briggs <r...@redhat.com>
> ---
>  kernel/auditsc.c | 28 +++++++++++++++++++++-------
>  1 file changed, 21 insertions(+), 7 deletions(-)
> 
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index f000fec52360..0f747015c577 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2908,22 +2908,36 @@ void __audit_fanotify(u32 response, size_t len,
> char *buf)
> 
>       if (!(len && buf)) {
>               audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> -                       "resp=%u fan_type=0 fan_info=?", response);
> +                       "resp=%u fan_type=0 fan_info=3F", response); /* "?" */
>               return;
>       }
>       while (c >= sizeof(struct fanotify_response_info_header)) {
> +             struct audit_context *ctx = audit_context();
> +             struct audit_buffer *ab;
> +
>               friar = (struct fanotify_response_info_audit_rule *)buf;
>               switch (friar->hdr.type) {
>               case FAN_RESPONSE_INFO_AUDIT_RULE:
>                       if (friar->hdr.len < sizeof(*friar)) {
> -                             audit_log(audit_context(), GFP_KERNEL, 
> AUDIT_FANOTIFY,
> -                                       "resp=%u fan_type=%u 
> fan_info=(incomplete)",
> -                                       response, friar->hdr.type);
> +                             ab = audit_log_start(ctx, GFP_KERNEL, 
> AUDIT_FANOTIFY);
> +                             if (ab) {
> +                                     audit_log_format(ab, "resp=%u 
> fan_type=%u fan_info=",
> +                                                      response, 
> friar->hdr.type);
> +#define INCOMPLETE "(incomplete)"
> +                                     audit_log_n_hex(ab, INCOMPLETE, 
> sizeof(INCOMPLETE));
> +                                     audit_log_end(ab);
> +                             }
>                               return;
>                       }
> -                     audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
> -                               "resp=%u fan_type=%u fan_info=%u",
> -                               response, friar->hdr.type, friar->audit_rule);
> +                     ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_FANOTIFY);
> +                     if (ab) {
> +                             audit_log_format(ab, "resp=%u fan_type=%u 
> fan_info=",
> +                                              response, friar->hdr.type);
> +                             audit_log_n_hex(ab, (char *)&friar->audit_rule,
> +                                             sizeof(friar->audit_rule));

One thing to point out, the structure has a member audit_rule. It is
probably better to call it rule_number. This is because it has nothing to
do with any actual audit rule. It is a rule number meant to be recorded by
the audit system.

Also, that member is a __u32 type. Hex encoding that directly gives back a
__u32 when decoded - which is a bit unexpected since everything else is
strings. It would be better to convert the u32 to a base 10 string and then
hex encode that. A buffer of 12 bytes should be sufficient.

Thanks,
-Steve

> +                             audit_log_end(ab);
> +
> +                     }
>               }
>               c -= friar->hdr.len;
>               ib += friar->hdr.len;




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