[PATCH nft] evaluate: reject set in concatenation

[Pablo Neira Ayuso <pablo@netfilter.org>]

Consider the following ruleset.

 define ext_if = { "eth0", "eth1" }
 table ip filter {
    chain c {
        iifname . tcp dport { $ext_if . 22 } accept
    }
 }

Attempting to load this ruleset results in:

BUG: invalid expression type 'set' in setnft: netlink.c:304: __netlink_gen_concat_key: Assertion `0' failed.
Aborted (core dumped)

After this patch:

 # nft -f ruleset.nft
 ruleset.nft:1:17-40: Error: cannot use set in concatenation
 define ext_if = { "eth0", 127.0.0.0/24 }
                 ^^^^^^^^^^^^^^^^^^^^^^^^

Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1715
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/evaluate.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/evaluate.c b/src/evaluate.c
index 2196e92813d0..894987df7895 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1511,6 +1511,12 @@ static int expr_evaluate_concat(struct eval_ctx *ctx, struct expr **expr)
 
 		if (list_member_evaluate(ctx, &i) < 0)
 			return -1;
+
+		if (i->etype == EXPR_SET)
+			return expr_error(ctx->msgs, i,
+					  "cannot use %s in concatenation",
+					  expr_name(i));
+
 		flags &= i->flags;
 
 		if (!key && i->dtype->type == TYPE_INTEGER) {
-- 
2.30.2