From: Pablo Neira Ayuso pablo@netfilter.org
[ Upstream commit 6a33d8b73dfac0a41f3877894b38082bd0c9a5bc ]
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 --- net/netfilter/nf_tables_api.c | 36 +++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 803b24eb9da99..dcf3ed3d5af9d 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -9753,6 +9753,22 @@ 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); @@ -9838,9 +9854,7 @@ 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); @@ -10050,7 +10064,7 @@ 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; @@ -11051,6 +11065,7 @@ 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; @@ -11058,6 +11073,9 @@ 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)) rcu_barrier(); again: @@ -11080,6 +11098,8 @@ 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; @@ -11117,12 +11137,20 @@ 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));