[PATCH] Fix dumping vlan rules

[michael-dev@fami-braun.de]

From: "M. Braun" <michael-dev@fami-braun.de>

Given the following bridge rules:
1. ip protocol icmp accept
2. ether type vlan vlan type ip ip protocol icmp accept

The are currently both dumped by "nft list ruleset" as
1. ip protocol icmp accept
2. ip protocol icmp accept

Though, the netlink code actually is different

bridge filter FORWARD 4
  [ payload load 2b @ link header + 12 => reg 1 ]
  [ cmp eq reg 1 0x00000008 ]
  [ payload load 1b @ network header + 9 => reg 1 ]
  [ cmp eq reg 1 0x00000001 ]
  [ immediate reg 0 accept ]

bridge filter FORWARD 5 4
  [ payload load 2b @ link header + 12 => reg 1 ]
  [ cmp eq reg 1 0x00000081 ]
  [ payload load 2b @ link header + 16 => reg 1 ]
  [ cmp eq reg 1 0x00000008 ]
  [ payload load 1b @ network header + 9 => reg 1 ]
  [ cmp eq reg 1 0x00000001 ]
  [ immediate reg 0 accept ]

Fix this by avoiding the removal of all vlan statements
in the given example.

Signed-off-by: Michael Braun <michael-dev@fami-braun.de>
---
 src/payload.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/payload.c b/src/payload.c
index 3bf1ecc..905422a 100644
--- a/src/payload.c
+++ b/src/payload.c
@@ -506,6 +506,18 @@ static bool payload_may_dependency_kill(struct payload_dep_ctx *ctx,
 		     dep->left->payload.desc == &proto_ip6) &&
 		    expr->payload.base == PROTO_BASE_TRANSPORT_HDR)
 			return false;
+		/* Do not kill
+		 *  ether type vlan and vlan type ip and ip protocol icmp
+		 * into
+		 *  ip protocol icmp
+		 * as this lacks ether type vlan.
+		 * More generally speaking, do not kill protocol type
+		 * for stacked protocols if we only have protcol type matches.
+		 */
+		if (dep->left->etype == EXPR_PAYLOAD && dep->op == OP_EQ &&
+		    expr->flags & EXPR_F_PROTOCOL &&
+		    expr->payload.base == dep->left->payload.base)
+			return false;
 		break;
 	}
 
-- 
2.20.1