1 files changed, 49 insertions, 3 deletions

diff --git a/net/netfilter/nf_conntrack_proto_dccp.c b/net/netfilter/nf_conntrack_proto_dccp.c
index c1557d47ccd1..d4fd626d2b8c 100644
--- a/net/netfilter/nf_conntrack_proto_dccp.c
+++ b/net/netfilter/nf_conntrack_proto_dccp.c
@@ -432,9 +432,19 @@ static bool dccp_error(const struct dccp_hdr *dh,
 		       struct sk_buff *skb, unsigned int dataoff,
 		       const struct nf_hook_state *state)
 {
+	static const unsigned long require_seq48 = 1 << DCCP_PKT_REQUEST |
+						   1 << DCCP_PKT_RESPONSE |
+						   1 << DCCP_PKT_CLOSEREQ |
+						   1 << DCCP_PKT_CLOSE |
+						   1 << DCCP_PKT_RESET |
+						   1 << DCCP_PKT_SYNC |
+						   1 << DCCP_PKT_SYNCACK;
 	unsigned int dccp_len = skb->len - dataoff;
 	unsigned int cscov;
 	const char *msg;
+	u8 type;
+
+	BUILD_BUG_ON(DCCP_PKT_INVALID >= BITS_PER_LONG);
 
 	if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
 	    dh->dccph_doff * 4 > dccp_len) {
@@ -459,34 +469,70 @@ static bool dccp_error(const struct dccp_hdr *dh,
 		goto out_invalid;
 	}
 
-	if (dh->dccph_type >= DCCP_PKT_INVALID) {
+	type = dh->dccph_type;
+	if (type >= DCCP_PKT_INVALID) {
 		msg = "nf_ct_dccp: reserved packet type ";
 		goto out_invalid;
 	}
+
+	if (test_bit(type, &require_seq48) && !dh->dccph_x) {
+		msg = "nf_ct_dccp: type lacks 48bit sequence numbers";
+		goto out_invalid;
+	}
+
 	return false;
 out_invalid:
 	nf_l4proto_log_invalid(skb, state, IPPROTO_DCCP, "%s", msg);
 	return true;
 }
 
+struct nf_conntrack_dccp_buf {
+	struct dccp_hdr dh;	 /* generic header part */
+	struct dccp_hdr_ext ext; /* optional depending dh->dccph_x */
+	union {			 /* depends on header type */
+		struct dccp_hdr_ack_bits ack;
+		struct dccp_hdr_request req;
+		struct dccp_hdr_response response;
+		struct dccp_hdr_reset rst;
+	} u;
+};
+
+static struct dccp_hdr *
+dccp_header_pointer(const struct sk_buff *skb, int offset, const struct dccp_hdr *dh,
+		    struct nf_conntrack_dccp_buf *buf)
+{
+	unsigned int hdrlen = __dccp_hdr_len(dh);
+
+	if (hdrlen > sizeof(*buf))
+		return NULL;
+
+	return skb_header_pointer(skb, offset, hdrlen, buf);
+}
+
 int nf_conntrack_dccp_packet(struct nf_conn *ct, struct sk_buff *skb,
 			     unsigned int dataoff,
 			     enum ip_conntrack_info ctinfo,
 			     const struct nf_hook_state *state)
 {
 	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-	struct dccp_hdr _dh, *dh;
+	struct nf_conntrack_dccp_buf _dh;
 	u_int8_t type, old_state, new_state;
 	enum ct_dccp_roles role;
 	unsigned int *timeouts;
+	struct dccp_hdr *dh;
 
-	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
+	dh = skb_header_pointer(skb, dataoff, sizeof(*dh), &_dh.dh);
 	if (!dh)
 		return NF_DROP;
 
 	if (dccp_error(dh, skb, dataoff, state))
 		return -NF_ACCEPT;
 
+	/* pull again, including possible 48 bit sequences and subtype header */
+	dh = dccp_header_pointer(skb, dataoff, dh, &_dh);
+	if (!dh)
+		return NF_DROP;
+
 	type = dh->dccph_type;
 	if (!nf_ct_is_confirmed(ct) && !dccp_new(ct, skb, dh, state))
 		return -NF_ACCEPT;