[PATCH 7/8] audit: clean up AUDIT_GET/SET local variables and future-proof API

[Richard Guy Briggs]

Re-named confusing local variable names (status_set and status_get didn't agree
with their command type name) and reduced their scope.

Future-proof API changes by not depending on the exact size of the audit_status
struct.

Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
---
 kernel/audit.c |   51 +++++++++++++++++++++++++++------------------------
 1 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index acfa7a9..3d17670 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -635,7 +635,6 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
 	u32			seq;
 	void			*data;
-	struct audit_status	*status_get, status_set;
 	int			err;
 	struct audit_buffer	*ab;
 	u16			msg_type = nlh->nlmsg_type;
@@ -661,47 +660,51 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	data = nlmsg_data(nlh);
 
 	switch (msg_type) {
-	case AUDIT_GET:
-		status_set.enabled	 = audit_enabled;
-		status_set.failure	 = audit_failure;
-		status_set.pid		 = audit_pid;
-		status_set.rate_limit	 = audit_rate_limit;
-		status_set.backlog_limit = audit_backlog_limit;
-		status_set.lost		 = atomic_read(&audit_lost);
-		status_set.backlog	 = skb_queue_len(&audit_skb_queue);
+	case AUDIT_GET: {
+		struct audit_status	s;
+		s.enabled	 = audit_enabled;
+		s.failure	 = audit_failure;
+		s.pid		 = audit_pid;
+		s.rate_limit	 = audit_rate_limit;
+		s.backlog_limit = audit_backlog_limit;
+		s.lost		 = atomic_read(&audit_lost);
+		s.backlog	 = skb_queue_len(&audit_skb_queue);
 		audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
-				 &status_set, sizeof(status_set));
+				 &s, sizeof(s));
 		break;
-	case AUDIT_SET:
-		if (nlh->nlmsg_len < sizeof(struct audit_status))
-			return -EINVAL;
-		status_get   = (struct audit_status *)data;
-		if (status_get->mask & AUDIT_STATUS_ENABLED) {
-			err = audit_set_enabled(status_get->enabled);
+	}
+	case AUDIT_SET: {
+		struct audit_status	s;
+		memset(&s, 0, sizeof(s));
+		/* guard against past and future API changes */
+		memcpy(&s, data, min(sizeof(s), (size_t)nlh->nlmsg_len));
+		if (s.mask & AUDIT_STATUS_ENABLED) {
+			err = audit_set_enabled(s.enabled);
 			if (err < 0)
 				return err;
 		}
-		if (status_get->mask & AUDIT_STATUS_FAILURE) {
-			err = audit_set_failure(status_get->failure);
+		if (s.mask & AUDIT_STATUS_FAILURE) {
+			err = audit_set_failure(s.failure);
 			if (err < 0)
 				return err;
 		}
-		if (status_get->mask & AUDIT_STATUS_PID) {
-			int new_pid = status_get->pid;
+		if (s.mask & AUDIT_STATUS_PID) {
+			int new_pid = s.pid;
 
 			if (audit_enabled != AUDIT_OFF)
 				audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
 			audit_pid = new_pid;
 			audit_nlk_portid = NETLINK_CB(skb).portid;
 		}
-		if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
-			err = audit_set_rate_limit(status_get->rate_limit);
+		if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
+			err = audit_set_rate_limit(s.rate_limit);
 			if (err < 0)
 				return err;
 		}
-		if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
-			err = audit_set_backlog_limit(status_get->backlog_limit);
+		if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT)
+			err = audit_set_backlog_limit(s.backlog_limit);
 		break;
+	}
 	case AUDIT_USER:
 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
-- 
1.7.1