Re: [PATCH] audit: shorten PATH cap values when zero

On 2018-11-19 16:22, Paul Moore wrote: > On Fri, Nov 16, 2018 at 12:10 PM Richard Guy Briggs <rgb(a)redhat.com&gt; 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(a)redhat.com&gt; > > --- > > 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) { > > Let's use the existing cap_isclear() instead. I'll admit it is pretty > trivial, but somebody is surely going to complain about the > open-coding at some point so let's fix it now. Yes, thank you, I like that much better. > > + 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); > > Since you're doing a re-spin, you might as well drop the curly braces > here, they aren't needed. I agree that is efficient legal C, but that will violate Documentation/process/coding-style.rst:191

> > } > > } > > paul moore - RGB -- Richard Guy Briggs <rgb(a)redhat.com&gt; Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635