seccomp: audit abnormal end to a process due to seccomp

The audit system likes to collect information about processes that end
abnormally (SIGSEGV) as this may me useful intrusion detection information.
This patch adds audit support to collect information when seccomp forces a
task to exit because of misbehavior in a similar way.

Signed-off-by: Eric Paris <eparis@redhat.com>

2 files changed, 31 insertions, 21 deletions

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 7c49514..e9bcb93 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2529,6 +2529,25 @@ void __audit_mmap_fd(int fd, int flags)
 	context->type = AUDIT_MMAP;
 }
 
+static void audit_log_abend(struct audit_buffer *ab, char *reason, long signr)
+{
+	uid_t auid, uid;
+	gid_t gid;
+	unsigned int sessionid;
+
+	auid = audit_get_loginuid(current);
+	sessionid = audit_get_sessionid(current);
+	current_uid_gid(&uid, &gid);
+
+	audit_log_format(ab, "auid=%u uid=%u gid=%u ses=%u",
+			 auid, uid, gid, sessionid);
+	audit_log_task_context(ab);
+	audit_log_format(ab, " pid=%d comm=", current->pid);
+	audit_log_untrustedstring(ab, current->comm);
+	audit_log_format(ab, " reason=");
+	audit_log_string(ab, reason);
+	audit_log_format(ab, " sig=%ld", signr);
+}
 /**
  * audit_core_dumps - record information about processes that end abnormally
  * @signr: signal value
@@ -2539,10 +2558,6 @@ void __audit_mmap_fd(int fd, int flags)
 void audit_core_dumps(long signr)
 {
 	struct audit_buffer *ab;
-	u32 sid;
-	uid_t auid = audit_get_loginuid(current), uid;
-	gid_t gid;
-	unsigned int sessionid = audit_get_sessionid(current);
 
 	if (!audit_enabled)
 		return;
@@ -2551,24 +2566,17 @@ void audit_core_dumps(long signr)
 		return;
 
 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND);
-	current_uid_gid(&uid, &gid);
-	audit_log_format(ab, "auid=%u uid=%u gid=%u ses=%u",
-			 auid, uid, gid, sessionid);
-	security_task_getsecid(current, &sid);
-	if (sid) {
-		char *ctx = NULL;
-		u32 len;
+	audit_log_abend(ab, "memory violation", signr);
+	audit_log_end(ab);
+}
 
-		if (security_secid_to_secctx(sid, &ctx, &len))
-			audit_log_format(ab, " ssid=%u", sid);
-		else {
-			audit_log_format(ab, " subj=%s", ctx);
-			security_release_secctx(ctx, len);
-		}
-	}
-	audit_log_format(ab, " pid=%d comm=", current->pid);
-	audit_log_untrustedstring(ab, current->comm);
-	audit_log_format(ab, " sig=%ld", signr);
+void __audit_seccomp(unsigned long syscall)
+{
+	struct audit_buffer *ab;
+
+	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND);
+	audit_log_abend(ab, "seccomp", SIGKILL);
+	audit_log_format(ab, " syscall=%ld", syscall);
 	audit_log_end(ab);
 }
 
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 57d4b13..e8d76c5 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -6,6 +6,7 @@
  * This defines a simple but solid secure-computing mode.
  */
 
+#include <linux/audit.h>
 #include <linux/seccomp.h>
 #include <linux/sched.h>
 #include <linux/compat.h>
@@ -54,6 +55,7 @@ void __secure_computing(int this_syscall)
 #ifdef SECCOMP_DEBUG
 	dump_stack();
 #endif
+	audit_seccomp(this_syscall);
 	do_exit(SIGKILL);
 }