netdev - [PATCH net 3/4] netfilter: nf_tables: reverse order in rule replacement expansion

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Date:   Sat,  2 Oct 2021 12:08:32 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 3/4] netfilter: nf_tables: reverse order in rule replacement expansion

Deactivate old rule first, then append the new rule, so rule replacement
notification via netlink first reports the deletion of the old rule with
handle X in first place, then it adds the new rule (reusing the handle X
of the replaced old rule).

Note that the abort path releases the transaction that has been created
by nft_delrule() on error.

Fixes: ca08987885a1 ("netfilter: nf_tables: deactivate expressions in rule replecement routine")
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_tables_api.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 085783b14075..c8acd26c7201 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3419,17 +3419,15 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 	}
 
 	if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
+		err = nft_delrule(&ctx, old_rule);
+		if (err < 0)
+			goto err_destroy_flow_rule;
+
 		trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
 		if (trans == NULL) {
 			err = -ENOMEM;
 			goto err_destroy_flow_rule;
 		}
-		err = nft_delrule(&ctx, old_rule);
-		if (err < 0) {
-			nft_trans_destroy(trans);
-			goto err_destroy_flow_rule;
-		}
-
 		list_add_tail_rcu(&rule->list, &old_rule->list);
 	} else {
 		trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
-- 
2.30.2