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Commit 569ccae6 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: nf_tables: can't fail after linking rule into active rule list 



rules in nftables a free'd using kfree, but protected by rcu, i.e. we
must wait for a grace period to elapse.

Normal removal patch does this, but nf_tables_newrule() doesn't obey
this rule during error handling.

It calls nft_trans_rule_add() *after* linking rule, and, if that
fails to allocate memory, it unlinks the rule and then kfree() it --
this is unsafe.

Switch order -- first add rule to transaction list, THEN link it
to public list.

Note: nft_trans_rule_add() uses GFP_KERNEL; it will not fail so this
is not a problem in practice (spotted only during code review).

Fixes: 0628b123 ("netfilter: nfnetlink: add batch support and use it from nf_tables")
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent a6615743

net/netfilter/nf_tables_api.c

+32 −27
Original line number Diff line number Diff line
@@ -2361,7 +2361,10 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk, 
	}



	if (nlh->nlmsg_flags & NLM_F_REPLACE) {

		if (nft_is_active_next(net, old_rule)) {

		if (!nft_is_active_next(net, old_rule)) {

			err = -ENOENT;

			goto err2;

		}

		trans = nft_trans_rule_add(&ctx, NFT_MSG_DELRULE,

					   old_rule);

		if (trans == NULL) {
@@ -2370,32 +2373,34 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk, 
		}

		nft_deactivate_next(net, old_rule);

		chain->use--;



		if (nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule) == NULL) {

			err = -ENOMEM;

			goto err2;

		}



		list_add_tail_rcu(&rule->list, &old_rule->list);

	} else {

			err = -ENOENT;

		if (nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule) == NULL) {

			err = -ENOMEM;

			goto err2;

		}

	} else if (nlh->nlmsg_flags & NLM_F_APPEND)



		if (nlh->nlmsg_flags & NLM_F_APPEND) {

			if (old_rule)

				list_add_rcu(&rule->list, &old_rule->list);

			else

				list_add_tail_rcu(&rule->list, &chain->rules);

	else {

		 } else {

			if (old_rule)

				list_add_tail_rcu(&rule->list, &old_rule->list);

			else

				list_add_rcu(&rule->list, &chain->rules);

		}



	if (nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule) == NULL) {

		err = -ENOMEM;

		goto err3;

	}

	chain->use++;

	return 0;



err3:

	list_del_rcu(&rule->list);

err2:

	nf_tables_rule_destroy(&ctx, rule);

err1: