[PATCH] audit: shorten PATH cap values when zero
Steve Grubb
sgrubb at redhat.com
Mon Nov 19 04:59:40 UTC 2018
On Friday, November 16, 2018 12:10:01 PM EST Richard Guy Briggs wrote:
> Since the vast majority of files (99.993% on a typical system) have no
> fcaps, display "0" instead of the full zero-padded 16 hex digits in the
> two PATH record cap_f* fields to save netlink bandwidth and disk space.
>
> Simply changing the format to %x won't work since the value is two (or
> possibly more in the future) 32-bit hexadecimal values concatenated and
> bits in higher order values will be misrepresented.
>
> Passes audit-testsuite and userspace tools already work fine.
> Please see the github issue tracker for more details
> https://github.com/linux-audit/audit-kernel/issues/101
>
> Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
Ack.
Thanks for doing this. It helps to alleviate my concern about wasted disk
space for normal files.
-Steve
> ---
> kernel/audit.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 2a8058764aa6..90cbc89fd6d2 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -2057,11 +2057,16 @@ void audit_log_key(struct audit_buffer *ab, char
> *key) void audit_log_cap(struct audit_buffer *ab, char *prefix,
> kernel_cap_t *cap) {
> int i;
> -
> - audit_log_format(ab, " %s=", prefix);
> - CAP_FOR_EACH_U32(i) {
> - audit_log_format(ab, "%08x",
> - cap->cap[CAP_LAST_U32 - i]);
> + u32 nonzero = 0;
> +
> + CAP_FOR_EACH_U32(i)
> + nonzero |= cap->cap[CAP_LAST_U32 - i];
> + if (nonzero) {
> + audit_log_format(ab, " %s=", prefix);
> + CAP_FOR_EACH_U32(i)
> + audit_log_format(ab, "%08x", cap->cap[CAP_LAST_U32 - i]);
> + } else {
> + audit_log_format(ab, " %s=0", prefix);
> }
> }
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