The special nested attribute NFTA_RULE_COMPAT holds information about
any present l4proto match (given via '-p' parameter) in input. The match
is contained as meta expression as well, but some xtables extensions
explicitly check it's value (see e.g. xt_TPROXY).
This nested attribute is input only, the information is lost after
parsing (and initialization of compat extensions). So in order to feed a
rule back to kernel with zeroed counters, the attribute has to be
reconstructed based on the rule's expressions.
Other code paths are not affected since rule_to_cs() callback will
populate respective fields in struct iptables_command_state and 'add'
callback (which is the inverse to rule_to_cs()) calls add_compat() in
any case.
Signed-off-by: Phil Sutter <phil@xxxxxx>
---
iptables/nft.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/iptables/nft.c b/iptables/nft.c
index 83cf5fb703d3e..599c2f7e4c087 100644
--- a/iptables/nft.c
+++ b/iptables/nft.c
@@ -2897,6 +2897,44 @@ const char *nft_strerror(int err)
return strerror(err);
}
+static int recover_rule_compat(struct nftnl_rule *r)
+{
+ struct nftnl_expr_iter *iter;
+ struct nftnl_expr *e;
+ uint32_t reg;
+ int ret = -1;
+
+ iter = nftnl_expr_iter_create(r);
+ if (!iter)
+ return -1;
+
+next_expr:
+ e = nftnl_expr_iter_next(iter);
+ if (!e)
+ goto out;
+
+ if (strcmp("meta", nftnl_expr_get_str(e, NFTNL_EXPR_NAME)) ||
+ nftnl_expr_get_u32(e, NFTNL_EXPR_META_KEY) != NFT_META_L4PROTO)
+ goto next_expr;
+
+ reg = nftnl_expr_get_u32(e, NFTNL_EXPR_META_DREG);
+
+ e = nftnl_expr_iter_next(iter);
+ if (!e)
+ goto out;
+
+ if (strcmp("cmp", nftnl_expr_get_str(e, NFTNL_EXPR_NAME)) ||
+ reg != nftnl_expr_get_u32(e, NFTNL_EXPR_CMP_SREG))
+ goto next_expr;
+
+ add_compat(r, nftnl_expr_get_u8(e, NFTNL_EXPR_CMP_DATA),
+ nftnl_expr_get_u32(e, NFTNL_EXPR_CMP_OP) == NFT_CMP_NEQ);
+ ret = 0;
+out:
+ nftnl_expr_iter_destroy(iter);
+ return ret;
+}
+
struct chain_zero_data {
struct nft_handle *handle;
bool verbose;
@@ -2961,6 +2999,7 @@ static int __nft_chain_zero_counters(struct nftnl_chain *c, void *data)
* Unset RULE_POSITION for older kernels, we want to replace
* rule based on its handle only.
*/
+ recover_rule_compat(r);
nftnl_rule_unset(r, NFTNL_RULE_POSITION);
if (!batch_rule_add(h, NFT_COMPAT_RULE_REPLACE, r)) {
nftnl_rule_iter_destroy(iter);
--
2.24.0
