[nft PATCH 1/2] evaluate: reject: check the context in reject without reason for bridge and inet tables

[Alvaro Neira Ayuso <alvaroneay@gmail.com>]

In rules like:

  nft add rule inet filter input reject
or
  nft add rule bridge filter input reject

we use icmpx to reject it. But if we have network context, we also use type of
reject. With this patch, we check the network context. If we don't have context,
we still use icmpx. However, if we have rules with network context like:

  nft add rule inet meta nfproto ipv4 reject
or
  nft add rule bridge ether type ipv6 reject

We are going to use icmp or icmpv6 to reject it taking into account the network
context.

Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
---
 src/evaluate.c |   44 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/evaluate.c b/src/evaluate.c
index 63ba82e..2dd49fa 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1357,6 +1357,9 @@ static int stmt_evaluate_reject_family(struct eval_ctx *ctx, struct stmt *stmt,
 static int stmt_evaluate_reject_default(struct eval_ctx *ctx,
 					  struct stmt *stmt)
 {
+	int protocol;
+	const struct proto_desc *desc, *base;
+
 	switch (ctx->pctx.family) {
 	case NFPROTO_IPV4:
 	case NFPROTO_IPV6:
@@ -1368,9 +1371,46 @@ static int stmt_evaluate_reject_default(struct eval_ctx *ctx,
 			stmt->reject.icmp_code = ICMP6_DST_UNREACH_NOPORT;
 		break;
 	case NFPROTO_INET:
+		desc = ctx->pctx.protocol[PROTO_BASE_NETWORK_HDR].desc;
+		if (desc == NULL) {
+			stmt->reject.type = NFT_REJECT_ICMPX_UNREACH;
+			stmt->reject.icmp_code = NFT_REJECT_ICMPX_PORT_UNREACH;
+			break;
+		}
+		stmt->reject.type = NFT_REJECT_ICMP_UNREACH;
+		base = ctx->pctx.protocol[PROTO_BASE_LL_HDR].desc;
+		protocol = proto_find_num(base, desc);
+		switch (protocol) {
+		case NFPROTO_IPV4:
+			stmt->reject.family = NFPROTO_IPV4;
+			stmt->reject.icmp_code = ICMP_PORT_UNREACH;
+			break;
+		case NFPROTO_IPV6:
+			stmt->reject.family = NFPROTO_IPV6;
+			stmt->reject.icmp_code = ICMP6_DST_UNREACH_NOPORT;
+			break;
+		}
+		break;
 	case NFPROTO_BRIDGE:
-		stmt->reject.type = NFT_REJECT_ICMPX_UNREACH;
-		stmt->reject.icmp_code = NFT_REJECT_ICMPX_PORT_UNREACH;
+		desc = ctx->pctx.protocol[PROTO_BASE_NETWORK_HDR].desc;
+		if (desc == NULL) {
+			stmt->reject.type = NFT_REJECT_ICMPX_UNREACH;
+			stmt->reject.icmp_code = NFT_REJECT_ICMPX_PORT_UNREACH;
+			break;
+		}
+		stmt->reject.type = NFT_REJECT_ICMP_UNREACH;
+		base = ctx->pctx.protocol[PROTO_BASE_LL_HDR].desc;
+		protocol = proto_find_num(base, desc);
+		switch (protocol) {
+		case __constant_htons(ETH_P_IP):
+			stmt->reject.family = NFPROTO_IPV4;
+			stmt->reject.icmp_code = ICMP_PORT_UNREACH;
+			break;
+		case __constant_htons(ETH_P_IPV6):
+			stmt->reject.family = NFPROTO_IPV6;
+			stmt->reject.icmp_code = ICMP6_DST_UNREACH_NOPORT;
+			break;
+		}
 		break;
 	}
 	return 0;
-- 
1.7.10.4