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netfilter: nf_tables: fix GC transaction races with netns and netlink event exit path

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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: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pablo Neira Ayuso 2023-11-21 13:13:19 +01:00 committed by Greg Kroah-Hartman
parent 1398a0eee2
commit 29ff9b8efb
1 changed files with 25 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
net/netfilter/nf_tables_api.c
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@ -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));