On Sun, Feb 14, 2021 at 11:29:55PM -0500, Sasha Levin wrote: > This is a note to let you know that I've just added the patch titled > > netfilter: nftables: fix possible UAF over chains from packet path in > netns > > to the 4.19-stable tree which can be found at: > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > netfilter-nftables-fix-possible-uaf-over-chains-from.patch > and it can be found in the queue-4.19 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <sta...@vger.kernel.org> know about it. > > > > commit 142e293ce46a1c63cb167af6743e2b8abb6581df > Author: Pablo Neira Ayuso <pa...@netfilter.org> > Date: Tue Feb 2 16:07:37 2021 +0100 > > netfilter: nftables: fix possible UAF over chains from packet path in > netns > > [ Upstream commit 767d1216bff82507c945e92fe719dff2083bb2f4 ] > > Although hooks are released via call_rcu(), chain and rule objects are > immediately released while packets are still walking over these bits. > > This patch adds the .pre_exit callback which is invoked before > synchronize_rcu() in the netns framework to stay safe. > > Remove a comment which is not valid anymore since the core does not use > synchronize_net() anymore since 8c873e219970 ("netfilter: core: free > hooks with call_rcu"). > > Suggested-by: Florian Westphal <f...@strlen.de> > Fixes: df05ef874b28 ("netfilter: nf_tables: release objects on netns > destruction") > Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org> > Signed-off-by: Sasha Levin <sas...@kernel.org> > > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c > index 9cc8e92f4b000..e669e20120446 100644 > --- a/net/netfilter/nf_tables_api.c > +++ b/net/netfilter/nf_tables_api.c > @@ -7303,6 +7303,17 @@ int __nft_release_basechain(struct nft_ctx *ctx) > } > EXPORT_SYMBOL_GPL(__nft_release_basechain); > > +static void __nft_release_hooks(struct net *net) > +{ > + struct nft_table *table; > + struct nft_chain *chain; > + > + list_for_each_entry(table, &net->nft.tables, list) { > + list_for_each_entry(chain, &table->chains, list) > + nf_tables_unregister_hook(net, table, chain); > + } > +} > + > static void __nft_release_tables(struct net *net) > { > struct nft_flowtable *flowtable, *nf; > @@ -7318,10 +7329,6 @@ static void __nft_release_tables(struct net *net) > > list_for_each_entry_safe(table, nt, &net->nft.tables, list) { > ctx.family = table->family; > - > - list_for_each_entry(chain, &table->chains, list) > - nf_tables_unregister_hook(net, table, chain); > - /* No packets are walking on these chains anymore. */ > ctx.table = table; > list_for_each_entry(chain, &table->chains, list) { > ctx.chain = chain; > @@ -7368,6 +7375,11 @@ static int __net_init nf_tables_init_net(struct net > *net) > return 0; > } > > +static void __net_exit nf_tables_pre_exit_net(struct net *net) > +{ > + __nft_release_hooks(net); > +} > + > static void __net_exit nf_tables_exit_net(struct net *net) > { > mutex_lock(&net->nft.commit_mutex); > @@ -7379,8 +7391,9 @@ static void __net_exit nf_tables_exit_net(struct net > *net) > } > > static struct pernet_operations nf_tables_net_ops = { > - .init = nf_tables_init_net, > - .exit = nf_tables_exit_net, > + .init = nf_tables_init_net, > + .pre_exit = nf_tables_pre_exit_net, > + .exit = nf_tables_exit_net, > }; > > static int __init nf_tables_module_init(void)
This breaks the build in 4.19.y, so I've dropped it. Sasha, did it pass your builders? thanks, greg k-h
