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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: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Pablo Neira Ayuso 2023-09-22 18:30:19 +02:00 committed by Greg Kroah-Hartman
parent 59ee68c437
commit 41113aa569
1 changed files with 32 additions and 4 deletions
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36
net/netfilter/nf_tables_api.c
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@ -9413,6 +9413,22 @@ static void nft_set_commit_update(struct list_head *set_update_list)
}
}
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 = nft_pernet(net);
@ -9498,9 +9514,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
WRITE_ONCE(nft_net->base_seq, base_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);
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);
@ -9691,7 +9705,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
nf_tables_commit_audit_log(&adl, nft_net->base_seq);
WRITE_ONCE(nft_net->gc_seq, ++gc_seq);
nft_gc_seq_end(nft_net, gc_seq);
nf_tables_commit_release(net);
return 0;
@ -10674,6 +10688,7 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event,
struct net *net = n->net;
unsigned int deleted;
bool restart = false;
unsigned int gc_seq;
if (event != NETLINK_URELEASE || n->protocol != NETLINK_NETFILTER)
return NOTIFY_DONE;
@ -10681,6 +10696,9 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event,
nft_net = nft_pernet(net);
deleted = 0;
mutex_lock(&nft_net->commit_mutex);
gc_seq = nft_gc_seq_begin(nft_net);
if (!list_empty(&nf_tables_destroy_list))
nf_tables_trans_destroy_flush_work();
again:
@ -10703,6 +10721,8 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event,
if (restart)
goto again;
}
nft_gc_seq_end(nft_net, gc_seq);
mutex_unlock(&nft_net->commit_mutex);
return NOTIFY_DONE;
@ -10741,12 +10761,20 @@ 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 = nft_pernet(net);
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) ||
!list_empty(&nft_net->module_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));