[AUDIT] make audit=0 really stop audit messages

Some audit messages (namely configuration changes) are still emitted even if
the audit subsystem has been explicitly disabled.  This patch turns those
messages off as well.

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

1 files changed, 60 insertions, 131 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index 26ff925..7e29372 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -66,9 +66,9 @@
  * (Initialization happens after skb_init is called.) */
 static int	audit_initialized;
 
-/* 0 - no auditing
- * 1 - auditing enabled
- * 2 - auditing enabled and configuration is locked/unchangeable. */
+#define AUDIT_OFF	0
+#define AUDIT_ON	1
+#define AUDIT_LOCKED	2
 int		audit_enabled;
 
 /* Default state when kernel boots without any parameters. */
@@ -240,152 +240,90 @@ void audit_log_lost(const char *message)
 	}
 }
 
-static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sid)
+static int audit_log_config_change(char *function_name, int new, int old,
+				   uid_t loginuid, u32 sid, int allow_changes)
 {
-	int res, rc = 0, old = audit_rate_limit;
-
-	/* check if we are locked */
-	if (audit_enabled == 2)
-		res = 0;
-	else
-		res = 1;
+	struct audit_buffer *ab;
+	int rc = 0;
 
+	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
+	audit_log_format(ab, "%s=%d old=%d by auid=%u", function_name, new,
+			 old, loginuid);
 	if (sid) {
 		char *ctx = NULL;
 		u32 len;
-		if ((rc = selinux_sid_to_string(sid, &ctx, &len)) == 0) {
-			audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-				"audit_rate_limit=%d old=%d by auid=%u"
-				" subj=%s res=%d",
-				limit, old, loginuid, ctx, res);
+
+		rc = selinux_sid_to_string(sid, &ctx, &len);
+		if (rc) {
+			audit_log_format(ab, " sid=%u", sid);
+			allow_changes = 0; /* Something weird, deny request */
+		} else {
+			audit_log_format(ab, " subj=%s", ctx);
 			kfree(ctx);
-		} else
-			res = 0; /* Something weird, deny request */
+		}
 	}
-	audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-		"audit_rate_limit=%d old=%d by auid=%u res=%d",
-		limit, old, loginuid, res);
-
-	/* If we are allowed, make the change */
-	if (res == 1)
-		audit_rate_limit = limit;
-	/* Not allowed, update reason */
-	else if (rc == 0)
-		rc = -EPERM;
+	audit_log_format(ab, " res=%d", allow_changes);
+	audit_log_end(ab);
 	return rc;
 }
 
-static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sid)
+static int audit_do_config_change(char *function_name, int *to_change,
+				  int new, uid_t loginuid, u32 sid)
 {
-	int res, rc = 0, old = audit_backlog_limit;
+	int allow_changes, rc = 0, old = *to_change;
 
 	/* check if we are locked */
-	if (audit_enabled == 2)
-		res = 0;
+	if (audit_enabled == AUDIT_LOCKED)
+		allow_changes = 0;
 	else
-		res = 1;
+		allow_changes = 1;
 
-	if (sid) {
-		char *ctx = NULL;
-		u32 len;
-		if ((rc = selinux_sid_to_string(sid, &ctx, &len)) == 0) {
-			audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-				"audit_backlog_limit=%d old=%d by auid=%u"
-				" subj=%s res=%d",
-				limit, old, loginuid, ctx, res);
-			kfree(ctx);
-		} else
-			res = 0; /* Something weird, deny request */
+	if (audit_enabled != AUDIT_OFF) {
+		rc = audit_log_config_change(function_name, new, old,
+					     loginuid, sid, allow_changes);
+		if (rc)
+			allow_changes = 0;
 	}
-	audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-		"audit_backlog_limit=%d old=%d by auid=%u res=%d",
-		limit, old, loginuid, res);
 
 	/* If we are allowed, make the change */
-	if (res == 1)
-		audit_backlog_limit = limit;
+	if (allow_changes == 1)
+		*to_change = new;
 	/* Not allowed, update reason */
 	else if (rc == 0)
 		rc = -EPERM;
 	return rc;
 }
 
-static int audit_set_enabled(int state, uid_t loginuid, u32 sid)
+static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sid)
 {
-	int res, rc = 0, old = audit_enabled;
-
-	if (state < 0 || state > 2)
-		return -EINVAL;
+	return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
+				      limit, loginuid, sid);
+}
 
-	/* check if we are locked */
-	if (audit_enabled == 2)
-		res = 0;
-	else
-		res = 1;
+static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sid)
+{
+	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
+				      limit, loginuid, sid);
+}
 
-	if (sid) {
-		char *ctx = NULL;
-		u32 len;
-		if ((rc = selinux_sid_to_string(sid, &ctx, &len)) == 0) {
-			audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-				"audit_enabled=%d old=%d by auid=%u"
-				" subj=%s res=%d",
-				state, old, loginuid, ctx, res);
-			kfree(ctx);
-		} else
-			res = 0; /* Something weird, deny request */
-	}
-	audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-		"audit_enabled=%d old=%d by auid=%u res=%d",
-		state, old, loginuid, res);
+static int audit_set_enabled(int state, uid_t loginuid, u32 sid)
+{
+	if (state < AUDIT_OFF || state > AUDIT_LOCKED)
+		return -EINVAL;
 
-	/* If we are allowed, make the change */
-	if (res == 1)
-		audit_enabled = state;
-	/* Not allowed, update reason */
-	else if (rc == 0)
-		rc = -EPERM;
-	return rc;
+	return audit_do_config_change("audit_enabled", &audit_enabled, state,
+				      loginuid, sid);
 }
 
 static int audit_set_failure(int state, uid_t loginuid, u32 sid)
 {
-	int res, rc = 0, old = audit_failure;
-
 	if (state != AUDIT_FAIL_SILENT
 	    && state != AUDIT_FAIL_PRINTK
 	    && state != AUDIT_FAIL_PANIC)
 		return -EINVAL;
 
-	/* check if we are locked */
-	if (audit_enabled == 2)
-		res = 0;
-	else
-		res = 1;
-
-	if (sid) {
-		char *ctx = NULL;
-		u32 len;
-		if ((rc = selinux_sid_to_string(sid, &ctx, &len)) == 0) {
-			audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-				"audit_failure=%d old=%d by auid=%u"
-				" subj=%s res=%d",
-				state, old, loginuid, ctx, res);
-			kfree(ctx);
-		} else
-			res = 0; /* Something weird, deny request */
-	}
-	audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-		"audit_failure=%d old=%d by auid=%u res=%d",
-		state, old, loginuid, res);
-
-	/* If we are allowed, make the change */
-	if (res == 1)
-		audit_failure = state;
-	/* Not allowed, update reason */
-	else if (rc == 0)
-		rc = -EPERM;
-	return rc;
+	return audit_do_config_change("audit_failure", &audit_failure, state,
+				      loginuid, sid);
 }
 
 static int kauditd_thread(void *dummy)
@@ -634,23 +572,14 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 			if (err < 0) return err;
 		}
 		if (status_get->mask & AUDIT_STATUS_PID) {
-			int old   = audit_pid;
-			if (sid) {
-				if ((err = selinux_sid_to_string(
-						sid, &ctx, &len)))
-					return err;
-				else
-					audit_log(NULL, GFP_KERNEL,
-						AUDIT_CONFIG_CHANGE,
-						"audit_pid=%d old=%d by auid=%u subj=%s",
-						status_get->pid, old,
-						loginuid, ctx);
-				kfree(ctx);
-			} else
-				audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-					"audit_pid=%d old=%d by auid=%u",
-					  status_get->pid, old, loginuid);
-			audit_pid = status_get->pid;
+			int new_pid = status_get->pid;
+
+			if (audit_enabled != AUDIT_OFF)
+				audit_log_config_change("audit_pid", new_pid,
+							audit_pid, loginuid,
+							sid, 1);
+
+			audit_pid = new_pid;
 		}
 		if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
 			err = audit_set_rate_limit(status_get->rate_limit,
@@ -709,7 +638,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	case AUDIT_DEL:
 		if (nlmsg_len(nlh) < sizeof(struct audit_rule))
 			return -EINVAL;
-		if (audit_enabled == 2) {
+		if (audit_enabled == AUDIT_LOCKED) {
 			ab = audit_log_start(NULL, GFP_KERNEL,
 					AUDIT_CONFIG_CHANGE);
 			if (ab) {
@@ -743,7 +672,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	case AUDIT_DEL_RULE:
 		if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 			return -EINVAL;
-		if (audit_enabled == 2) {
+		if (audit_enabled == AUDIT_LOCKED) {
 			ab = audit_log_start(NULL, GFP_KERNEL,
 					AUDIT_CONFIG_CHANGE);
 			if (ab) {