evaluate: do not remove anonymous set with protocol flags and single element

commit 01167c393a12c74c6f9a3015b75702964ff5bcda upstream.

Set lookups with flags search for an exact match, however:

	tcp flags { syn }

gets transformed into:

	tcp flags syn

which is matching on the syn flag only (non-exact match).

This optimization is safe for ct state though, because only one bit is
ever set on in the ct state bitmask.

Since protocol flags allow for combining flags, skip this optimization
to retain exact match semantics.

Another possible solution is to turn OP_IMPLICIT into OP_EQ for exact
flag match to re-introduce this optimization and deal with this corner
case.

Fixes: fee6bda06403 ("evaluate: remove anon sets with exactly one element")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/evaluate.c b/src/evaluate.c
index 937889a2ba2199e919e90ec6db02cfec52109b4d..5ceb41a20a3ba025a65d399f89c32d86242a0695 100644 (file)
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1669,7 +1669,12 @@ static int expr_evaluate_set(struct eval_ctx *ctx, struct expr **expr)
                        set->set_flags |= NFT_SET_CONCAT;
        } else if (set->size == 1) {
                i = list_first_entry(&set->expressions, struct expr, list);
-               if (i->etype == EXPR_SET_ELEM && list_empty(&i->stmt_list)) {
+               if (i->etype == EXPR_SET_ELEM &&
+                   (!i->dtype->basetype ||
+                    i->dtype->basetype->type != TYPE_BITMASK ||
+                    i->dtype->type == TYPE_CT_STATE) &&
+                   list_empty(&i->stmt_list)) {
+
                        switch (i->key->etype) {
                        case EXPR_PREFIX:
                        case EXPR_RANGE: