From 30969bc8e0751a5e5d44896c0632bc688abfa86f Mon Sep 17 00:00:00 2001 From: Peter Enderborg Date: Fri, 21 Aug 2020 16:08:22 +0200 Subject: selinux: add basic filtering for audit trace events MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch adds further attributes to the event. These attributes are helpful to understand the context of the message and can be used to filter the events. There are three common items. Source context, target context and tclass. There are also items from the outcome of operation performed. An event is similar to: <...>-1309 [002] .... 6346.691689: selinux_audited: requested=0x4000000 denied=0x4000000 audited=0x4000000 result=-13 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:bin_t:s0 tclass=file With systems where many denials are occurring, it is useful to apply a filter. The filtering is a set of logic that is inserted with the filter file. Example: echo "tclass==\"file\" " > events/avc/selinux_audited/filter This adds that we only get tclass=file. The trace can also have extra properties. Adding the user stack can be done with echo 1 > options/userstacktrace Now the output will be runcon-1365 [003] .... 6960.955530: selinux_audited: requested=0x4000000 denied=0x4000000 audited=0x4000000 result=-13 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:bin_t:s0 tclass=file runcon-1365 [003] .... 6960.955560: => <00007f325b4ce45b> => <00005607093efa57> Signed-off-by: Peter Enderborg Reviewed-by: Thiébaud Weksteen Acked-by: Stephen Smalley Signed-off-by: Paul Moore --- security/selinux/avc.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) (limited to 'security/selinux/avc.c') diff --git a/security/selinux/avc.c b/security/selinux/avc.c index b0a0af778b70..3c05827608b6 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -705,35 +705,37 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a) { struct common_audit_data *ad = a; struct selinux_audit_data *sad = ad->selinux_audit_data; - char *scontext; + char *scontext = NULL; + char *tcontext = NULL; + const char *tclass = NULL; u32 scontext_len; + u32 tcontext_len; int rc; - trace_selinux_audited(sad); - rc = security_sid_to_context(sad->state, sad->ssid, &scontext, &scontext_len); if (rc) audit_log_format(ab, " ssid=%d", sad->ssid); - else { + else audit_log_format(ab, " scontext=%s", scontext); - kfree(scontext); - } - rc = security_sid_to_context(sad->state, sad->tsid, &scontext, - &scontext_len); + rc = security_sid_to_context(sad->state, sad->tsid, &tcontext, + &tcontext_len); if (rc) audit_log_format(ab, " tsid=%d", sad->tsid); - else { - audit_log_format(ab, " tcontext=%s", scontext); - kfree(scontext); - } + else + audit_log_format(ab, " tcontext=%s", tcontext); - audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name); + tclass = secclass_map[sad->tclass-1].name; + audit_log_format(ab, " tclass=%s", tclass); if (sad->denied) audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1); + trace_selinux_audited(sad, scontext, tcontext, tclass); + kfree(tcontext); + kfree(scontext); + /* in case of invalid context report also the actual context string */ rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext, &scontext_len); -- cgit v1.2.3