From b00fc8cd1379f6e403538943d55d297b624f185b Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Thu, 20 Mar 2025 09:34:45 +0100
Subject: [PATCH] expression: tolerate named set protocol dependency

Included test will fail with:
/dev/stdin:8:38-52: Error: Transparent proxy support requires transport protocol match
   meta l4proto @protos tproxy to :1088
                        ^^^^^^^^^^^^^^^
Tolerate a set reference too.  Because the set can be empty (or there
can be removals later), add a fake 0-rhs value.

This will make pctx_update assign proto_unknown as the transport protocol
in use, Thats enough to avoid 'requires transport protocol' error.

v2: restrict it to meta lhs for now (Pablo Neira Ayuso)

Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1686
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/expression.c                              | 11 +++
 .../dumps/named_set_as_protocol_dep.json-nft  | 75 +++++++++++++++++++
 .../nft-f/dumps/named_set_as_protocol_dep.nft | 11 +++
 .../testcases/nft-f/named_set_as_protocol_dep |  5 ++
 4 files changed, 102 insertions(+)
 create mode 100644 tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.json-nft
 create mode 100644 tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.nft
 create mode 100755 tests/shell/testcases/nft-f/named_set_as_protocol_dep

diff --git a/src/expression.c b/src/expression.c
index 413f4467..156a66eb 100644
--- a/src/expression.c
+++ b/src/expression.c
@@ -945,6 +945,17 @@ void relational_expr_pctx_update(struct proto_ctx *ctx,
 				    i->key->etype == EXPR_VALUE)
 					ops->pctx_update(ctx, &expr->location, left, i->key);
 			}
+		} else if (ops == &meta_expr_ops &&
+			   right->etype == EXPR_SET_REF) {
+			const struct expr *key = right->set->key;
+			struct expr *tmp;
+
+			tmp = constant_expr_alloc(&expr->location, key->dtype,
+						  key->byteorder, key->len,
+						  NULL);
+
+			ops->pctx_update(ctx, &expr->location, left, tmp);
+			expr_free(tmp);
 		}
 	}
 }
diff --git a/tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.json-nft b/tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.json-nft
new file mode 100644
index 00000000..4bc24aa3
--- /dev/null
+++ b/tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.json-nft
@@ -0,0 +1,75 @@
+{
+  "nftables": [
+    {
+      "metainfo": {
+        "version": "VERSION",
+        "release_name": "RELEASE_NAME",
+        "json_schema_version": 1
+      }
+    },
+    {
+      "table": {
+        "family": "inet",
+        "name": "test",
+        "handle": 0
+      }
+    },
+    {
+      "chain": {
+        "family": "inet",
+        "table": "test",
+        "name": "prerouting",
+        "handle": 0,
+        "type": "filter",
+        "hook": "prerouting",
+        "prio": -150,
+        "policy": "accept"
+      }
+    },
+    {
+      "set": {
+        "family": "inet",
+        "name": "protos",
+        "table": "test",
+        "type": {
+          "typeof": {
+            "meta": {
+              "key": "l4proto"
+            }
+          }
+        },
+        "handle": 0,
+        "elem": [
+          "tcp",
+          "udp"
+        ]
+      }
+    },
+    {
+      "rule": {
+        "family": "inet",
+        "table": "test",
+        "chain": "prerouting",
+        "handle": 0,
+        "expr": [
+          {
+            "match": {
+              "op": "==",
+              "left": {
+                "meta": {
+                  "key": "l4proto"
+                }
+              },
+              "right": "@protos"
+            }
+          },
+          {
+            "tproxy": {
+              "port": 1088
+            }
+          }
+        ]
+      }
+    }
+  ]
+}
diff --git a/tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.nft b/tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.nft
new file mode 100644
index 00000000..2bc0c2ad
--- /dev/null
+++ b/tests/shell/testcases/nft-f/dumps/named_set_as_protocol_dep.nft
@@ -0,0 +1,11 @@
+table inet test {
+	set protos {
+		typeof meta l4proto
+		elements = { tcp, udp }
+	}
+
+	chain prerouting {
+		type filter hook prerouting priority mangle; policy accept;
+		meta l4proto @protos tproxy to :1088
+	}
+}
diff --git a/tests/shell/testcases/nft-f/named_set_as_protocol_dep b/tests/shell/testcases/nft-f/named_set_as_protocol_dep
new file mode 100755
index 00000000..5c516e42
--- /dev/null
+++ b/tests/shell/testcases/nft-f/named_set_as_protocol_dep
@@ -0,0 +1,5 @@
+#!/bin/bash
+
+dumpfile=$(dirname $0)/dumps/$(basename $0).nft
+
+$NFT -f "$dumpfile" || exit 1
-- 
2.47.2