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Commit 29ff9b8e authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso Committed by Greg Kroah-Hartman
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netfilter: nf_tables: fix GC transaction races with netns and netlink event exit path 



commit 6a33d8b73dfac0a41f3877894b38082bd0c9a5bc upstream.

Netlink event path is missing a synchronization point with GC
transactions. Add GC sequence number update to netns release path and
netlink event path, any GC transaction losing race will be discarded.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1398a0ee

net/netfilter/nf_tables_api.c

+25 −4
Original line number Diff line number Diff line
@@ -7178,6 +7178,22 @@ static void nf_tables_commit_release(struct net *net) 
	mutex_unlock(&nft_net->commit_mutex);

}



static unsigned int nft_gc_seq_begin(struct nftables_pernet *nft_net)

{

	unsigned int gc_seq;



	/* Bump gc counter, it becomes odd, this is the busy mark. */

	gc_seq = READ_ONCE(nft_net->gc_seq);

	WRITE_ONCE(nft_net->gc_seq, ++gc_seq);



	return gc_seq;

}



static void nft_gc_seq_end(struct nftables_pernet *nft_net, unsigned int gc_seq)

{

	WRITE_ONCE(nft_net->gc_seq, ++gc_seq);

}



static int nf_tables_commit(struct net *net, struct sk_buff *skb)

{

	struct nftables_pernet *nft_net = net_generic(net, nf_tables_net_id);
@@ -7242,9 +7258,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb) 
	while (++nft_net->base_seq == 0)

		;



	/* Bump gc counter, it becomes odd, this is the busy mark. */

	gc_seq = READ_ONCE(nft_net->gc_seq);

	WRITE_ONCE(nft_net->gc_seq, ++gc_seq);

	gc_seq = nft_gc_seq_begin(nft_net);



	/* step 3. Start new generation, rules_gen_X now in use. */

	net->nft.gencursor = nft_gencursor_next(net);
@@ -7386,7 +7400,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb) 


	nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);



	WRITE_ONCE(nft_net->gc_seq, ++gc_seq);

	nft_gc_seq_end(nft_net, gc_seq);

	nf_tables_commit_release(net);



	return 0;
@@ -8256,11 +8270,18 @@ static void __net_exit nf_tables_pre_exit_net(struct net *net) 
static void __net_exit nf_tables_exit_net(struct net *net)

{

	struct nftables_pernet *nft_net = net_generic(net, nf_tables_net_id);

	unsigned int gc_seq;



	mutex_lock(&nft_net->commit_mutex);



	gc_seq = nft_gc_seq_begin(nft_net);



	if (!list_empty(&nft_net->commit_list))

		__nf_tables_abort(net, NFNL_ABORT_NONE);

	__nft_release_tables(net);



	nft_gc_seq_end(nft_net, gc_seq);



	mutex_unlock(&nft_net->commit_mutex);

	WARN_ON_ONCE(!list_empty(&nft_net->tables));

	WARN_ON_ONCE(!list_empty(&nft_net->module_list));