src: context tracking for multiple transport protocols

This patch extends the protocol context infrastructure to track multiple
transport protocols when they are specified from sets.

This removes errors like:

 "transport protocol mapping is only valid after transport protocol match"

when invoking:

 # nft add rule x z meta l4proto { tcp, udp } dnat to 1.1.1.1:80

This patch also catches conflicts like:

 # nft add rule x z ip protocol { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
 Error: conflicting protocols specified: udp vs. tcp
 add rule x z ip protocol { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
                                       ^^^^^^^^^
and:

 # nft add rule x z meta l4proto { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
 Error: conflicting protocols specified: udp vs. tcp
 add rule x z meta l4proto { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
                                        ^^^^^^^^^
Note that:

- the singleton protocol context tracker is left in place until the
  existing users are updated to use this new multiprotocol tracker.
  Moving forward, it would be good to consolidate things around this new
  multiprotocol context tracker infrastructure.

- link and network layers are not updated to use this infrastructure
  yet. The code that deals with vlan conflicts relies on forcing
  protocol context updates to the singleton protocol base.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 12 insertions, 2 deletions

diff --git a/src/evaluate.c b/src/evaluate.c
index e3fe7062..c8045e5d 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -710,6 +710,17 @@ static int __expr_evaluate_payload(struct eval_ctx *ctx, struct expr *expr)
 		return 0;
 	}
 
+	if (payload->payload.base == desc->base &&
+	    proto_ctx_is_ambiguous(&ctx->pctx, base)) {
+		desc = proto_ctx_find_conflict(&ctx->pctx, base, payload->payload.desc);
+		assert(desc);
+
+		return expr_error(ctx->msgs, payload,
+				  "conflicting protocols specified: %s vs. %s",
+				  desc->name,
+				  payload->payload.desc->name);
+	}
+
 	/* No conflict: Same payload protocol as context, adjust offset
 	 * if needed.
 	 */
@@ -1874,8 +1885,7 @@ static int expr_evaluate_relational(struct eval_ctx *ctx, struct expr **expr)
 		 * Update protocol context for payload and meta iiftype
 		 * equality expressions.
 		 */
-		if (expr_is_singleton(right))
-			relational_expr_pctx_update(&ctx->pctx, rel);
+		relational_expr_pctx_update(&ctx->pctx, rel);
 
 		/* fall through */
 	case OP_NEQ: