[MLSXFRM]: Add security context to acquire messages using PF_KEY

This includes the security context of a security association created
for use by IKE in the acquire messages sent to IKE daemons using
PF_KEY. This would allow the daemons to include the security context
in the negotiation, so that the resultant association is unique to
that security context.
Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/key/af_key.c

@@ -2708,6 +2708,9 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
 #endif
 	int sockaddr_size;
 	int size;
+	struct sadb_x_sec_ctx *sec_ctx;
+	struct xfrm_sec_ctx *xfrm_ctx;
+	int ctx_size = 0;
 	
 	sockaddr_size = pfkey_sockaddr_size(x->props.family);
 	if (!sockaddr_size)
@@ -2723,6 +2726,11 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
 	else if (x->id.proto == IPPROTO_ESP)
 		size += count_esp_combs(t);
 
+	if ((xfrm_ctx = x->security)) {
+		ctx_size = PFKEY_ALIGN8(xfrm_ctx->ctx_len);
+		size +=  sizeof(struct sadb_x_sec_ctx) + ctx_size;
+	}
+
 	skb =  alloc_skb(size + 16, GFP_ATOMIC);
 	if (skb == NULL)
 		return -ENOMEM;
@@ -2818,6 +2826,20 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
 	else if (x->id.proto == IPPROTO_ESP)
 		dump_esp_combs(skb, t);
 
+	/* security context */
+	if (xfrm_ctx) {
+		sec_ctx = (struct sadb_x_sec_ctx *) skb_put(skb,
+				sizeof(struct sadb_x_sec_ctx) + ctx_size);
+		sec_ctx->sadb_x_sec_len =
+		  (sizeof(struct sadb_x_sec_ctx) + ctx_size) / sizeof(uint64_t);
+		sec_ctx->sadb_x_sec_exttype = SADB_X_EXT_SEC_CTX;
+		sec_ctx->sadb_x_ctx_doi = xfrm_ctx->ctx_doi;
+		sec_ctx->sadb_x_ctx_alg = xfrm_ctx->ctx_alg;
+		sec_ctx->sadb_x_ctx_len = xfrm_ctx->ctx_len;
+		memcpy(sec_ctx + 1, xfrm_ctx->ctx_str,
+		       xfrm_ctx->ctx_len);
+	}
+
 	return pfkey_broadcast(skb, GFP_ATOMIC, BROADCAST_REGISTERED, NULL);
 }