xfrm: Restrict SA direction attribute to specific netlink message types

Reject the usage of the SA_DIR attribute in xfrm netlink messages when
it's not applicable. This ensures that SA_DIR is only accepted for
certain message types (NEWSA, UPDSA, and ALLOCSPI)
Signed-off-by: Antony Antony <antony.antony@secunet.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_user.c

@@ -3213,6 +3213,24 @@ static const struct xfrm_link {
 	[XFRM_MSG_GETDEFAULT  - XFRM_MSG_BASE] = { .doit = xfrm_get_default   },
 };
 
+static int xfrm_reject_unused_attr(int type, struct nlattr **attrs,
+				   struct netlink_ext_ack *extack)
+{
+	if (attrs[XFRMA_SA_DIR]) {
+		switch (type) {
+		case XFRM_MSG_NEWSA:
+		case XFRM_MSG_UPDSA:
+		case XFRM_MSG_ALLOCSPI:
+			break;
+		default:
+			NL_SET_ERR_MSG(extack, "Invalid attribute SA_DIR");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 			     struct netlink_ext_ack *extack)
 {
@@ -3272,6 +3290,12 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err < 0)
 		goto err;
 
+	if (!link->nla_pol || link->nla_pol == xfrma_policy) {
+		err = xfrm_reject_unused_attr((type + XFRM_MSG_BASE), attrs, extack);
+		if (err < 0)
+			goto err;
+	}
+
 	if (link->doit == NULL) {
 		err = -EINVAL;
 		goto err;