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| author | Pablo Neira Ayuso <pablo@netfilter.org> | 2021-02-02 16:07:37 +0100 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2021-02-04 00:33:09 +0100 |
| commit | 767d1216bff82507c945e92fe719dff2083bb2f4 (patch) | |
| tree | 89aa5dc4df79d38b67a479ace62e396d3b78dd11 /net | |
| parent | a3005b0f83f217c888393c6bf9cd36e3d1616bca (diff) | |
| download | lwn-767d1216bff82507c945e92fe719dff2083bb2f4.tar.gz lwn-767d1216bff82507c945e92fe719dff2083bb2f4.zip | |
netfilter: nftables: fix possible UAF over chains from packet path in netns
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 <fw@strlen.de>
Fixes: df05ef874b28 ("netfilter: nf_tables: release objects on netns destruction")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/nf_tables_api.c | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 8d3aa97b52e7..43fe80f10313 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -8949,6 +8949,17 @@ 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; @@ -8964,10 +8975,6 @@ 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; @@ -9016,6 +9023,11 @@ 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); @@ -9029,8 +9041,9 @@ 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) |