5.4-stable review patch. If anyone has any objections, please let me know.
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From: Pablo Neira Ayuso pablo@netfilter.org
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 --- net/netfilter/nf_tables_api.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-)
--- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -7178,6 +7178,22 @@ static void nf_tables_commit_release(str 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 * 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 *
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_exi 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));