Handle non-compressed packets for IPComp in tunnel mode.

RFC3173 says that the IP datagram MUST be sent in the original
non-compressed form, when the total size of a compressed payload
and the IPComp header is not smaller than the size of the original
payload. In tunnel mode for small packets IPComp will send
encapsulated IP datagrams without IPComp header.
Add ip_encap handler for IPPROTO_IPV4 and IPPROTO_IPV6 to handle
these datagrams. The handler does lookup for SA related to IPComp
protocol and given from mbuf source and destination addresses as
tunnel endpoints. It decapsulates packets only when corresponding SA
is found.

Reported by:	gnn
Reviewed by:	gnn
Differential Revision:	https://reviews.freebsd.org/D6062

(cherry picked from commit dcf50398ab66cfcba0ae4484efe3b5ce40fb9824)

1 files changed, 60 insertions, 0 deletions

diff --git a/sys/netipsec/key.c b/sys/netipsec/key.c
index 7705a63..c199741 100644
--- a/sys/netipsec/key.c
+++ b/sys/netipsec/key.c
@@ -1153,6 +1153,66 @@ done:
 	return sav;
 }
 
+struct secasvar *
+key_allocsa_tunnel(union sockaddr_union *src, union sockaddr_union *dst,
+    u_int proto, const char* where, int tag)
+{
+	struct secashead *sah;
+	struct secasvar *sav;
+	u_int stateidx, arraysize, state;
+	const u_int *saorder_state_valid;
+
+	IPSEC_ASSERT(src != NULL, ("null src address"));
+	IPSEC_ASSERT(dst != NULL, ("null dst address"));
+	KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
+		printf("DP %s from %s:%u\n", __func__, where, tag));
+
+	SAHTREE_LOCK();
+	if (V_key_preferred_oldsa) {
+		saorder_state_valid = saorder_state_valid_prefer_old;
+		arraysize = _ARRAYLEN(saorder_state_valid_prefer_old);
+	} else {
+		saorder_state_valid = saorder_state_valid_prefer_new;
+		arraysize = _ARRAYLEN(saorder_state_valid_prefer_new);
+	}
+	LIST_FOREACH(sah, &V_sahtree, chain) {
+		/* search valid state */
+		for (stateidx = 0; stateidx < arraysize; stateidx++) {
+			state = saorder_state_valid[stateidx];
+			LIST_FOREACH(sav, &sah->savtree[state], chain) {
+				/* sanity check */
+				KEY_CHKSASTATE(sav->state, state, __func__);
+				/* do not return entries w/ unusable state */
+				if (sav->state != SADB_SASTATE_MATURE &&
+				    sav->state != SADB_SASTATE_DYING)
+					continue;
+				if (IPSEC_MODE_TUNNEL != sav->sah->saidx.mode)
+					continue;
+				if (proto != sav->sah->saidx.proto)
+					continue;
+				/* check src address */
+				if (key_sockaddrcmp(&src->sa,
+				    &sav->sah->saidx.src.sa, 0) != 0)
+					continue;
+				/* check dst address */
+				if (key_sockaddrcmp(&dst->sa,
+				    &sav->sah->saidx.dst.sa, 0) != 0)
+					continue;
+				sa_addref(sav);
+				goto done;
+			}
+		}
+	}
+	sav = NULL;
+done:
+	SAHTREE_UNLOCK();
+
+	KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
+		printf("DP %s return SA:%p; refcnt %u\n", __func__,
+			sav, sav ? sav->refcnt : 0));
+	return (sav);
+}
+
 /*
  * Must be called after calling key_allocsp().
  * For both the packet without socket and key_freeso().