[XFRM] netlink: Use nlmsg_parse() to parse attributes

Uses nlmsg_parse() to parse the attributes. This actually changes
behaviour as unknown attributes (type > MAXTYPE) no longer cause
an error. Instead unknown attributes will be ignored henceforth
to keep older kernels compatible with more recent userspace tools.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/xfrm_user.c

@@ -1890,7 +1890,7 @@ static int xfrm_send_migrate(struct xfrm_selector *sel, u8 dir, u8 type,
 }
 #endif
 
-#define XMSGSIZE(type) NLMSG_LENGTH(sizeof(struct type))
+#define XMSGSIZE(type) sizeof(struct type)
 
 static const int xfrm_msg_min[XFRM_NR_MSGTYPES] = {
 	[XFRM_MSG_NEWSA       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_info),
@@ -1906,13 +1906,13 @@ static const int xfrm_msg_min[XFRM_NR_MSGTYPES] = {
 	[XFRM_MSG_UPDSA       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_info),
 	[XFRM_MSG_POLEXPIRE   - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_polexpire),
 	[XFRM_MSG_FLUSHSA     - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_flush),
-	[XFRM_MSG_FLUSHPOLICY - XFRM_MSG_BASE] = NLMSG_LENGTH(0),
+	[XFRM_MSG_FLUSHPOLICY - XFRM_MSG_BASE] = 0,
 	[XFRM_MSG_NEWAE       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_aevent_id),
 	[XFRM_MSG_GETAE       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_aevent_id),
 	[XFRM_MSG_REPORT      - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_report),
 	[XFRM_MSG_MIGRATE     - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_id),
-	[XFRM_MSG_GETSADINFO  - XFRM_MSG_BASE] = NLMSG_LENGTH(sizeof(u32)),
-	[XFRM_MSG_GETSPDINFO  - XFRM_MSG_BASE] = NLMSG_LENGTH(sizeof(u32)),
+	[XFRM_MSG_GETSADINFO  - XFRM_MSG_BASE] = sizeof(u32),
+	[XFRM_MSG_GETSPDINFO  - XFRM_MSG_BASE] = sizeof(u32),
 };
 
 #undef XMSGSIZE
@@ -1946,9 +1946,9 @@ static struct xfrm_link {
 
 static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
-	struct rtattr *xfrma[XFRMA_MAX];
+	struct nlattr *xfrma[XFRMA_MAX+1];
 	struct xfrm_link *link;
-	int type, min_len;
+	int type, err;
 
 	type = nlh->nlmsg_type;
 	if (type > XFRM_MSG_MAX)
@@ -1970,30 +1970,16 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		return netlink_dump_start(xfrm_nl, skb, nlh, link->dump, NULL);
 	}
 
-	memset(xfrma, 0, sizeof(xfrma));
-
-	if (nlh->nlmsg_len < (min_len = xfrm_msg_min[type]))
-		return -EINVAL;
-
-	if (nlh->nlmsg_len > min_len) {
-		int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
-		struct rtattr *attr = (void *) nlh + NLMSG_ALIGN(min_len);
-
-		while (RTA_OK(attr, attrlen)) {
-			unsigned short flavor = attr->rta_type;
-			if (flavor) {
-				if (flavor > XFRMA_MAX)
-					return -EINVAL;
-				xfrma[flavor - 1] = attr;
-			}
-			attr = RTA_NEXT(attr, attrlen);
-		}
-	}
+	/* FIXME: Temporary hack, nlmsg_parse() starts at xfrma[1], old code
+	 * expects first attribute at xfrma[0] */
+	err = nlmsg_parse(nlh, xfrm_msg_min[type], xfrma-1, XFRMA_MAX, NULL);
+	if (err < 0)
+		return err;
 
 	if (link->doit == NULL)
 		return -EINVAL;
 
-	return link->doit(skb, nlh, xfrma);
+	return link->doit(skb, nlh, (struct rtattr **) xfrma);
 }
 
 static void xfrm_netlink_rcv(struct sock *sk, int len)