From a45e6889575c2067d3c0212b6bc1022891e65b91 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 28 Mar 2024 13:27:36 +0100 Subject: [PATCH 1/6] netfilter: nf_tables: release batch on table validation from abort path Unlike early commit path stage which triggers a call to abort, an explicit release of the batch is required on abort, otherwise mutex is released and commit_list remains in place. Add WARN_ON_ONCE to ensure commit_list is empty from the abort path before releasing the mutex. After this patch, commit_list is always assumed to be empty before grabbing the mutex, therefore 03c1f1ef1584 ("netfilter: Cleanup nft_net->module_list from nf_tables_exit_net()") only needs to release the pending modules for registration. Cc: stable@vger.kernel.org Fixes: c0391b6ab810 ("netfilter: nf_tables: missing validation from the abort path") Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index fd86f2720c9e..ffcd3213c335 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -10455,10 +10455,11 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action) struct nft_trans *trans, *next; LIST_HEAD(set_update_list); struct nft_trans_elem *te; + int err = 0; if (action == NFNL_ABORT_VALIDATE && nf_tables_validate(net) < 0) - return -EAGAIN; + err = -EAGAIN; list_for_each_entry_safe_reverse(trans, next, &nft_net->commit_list, list) { @@ -10655,7 +10656,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action) else nf_tables_module_autoload_cleanup(net); - return 0; + return err; } static int nf_tables_abort(struct net *net, struct sk_buff *skb, @@ -10668,6 +10669,9 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb, gc_seq = nft_gc_seq_begin(nft_net); ret = __nf_tables_abort(net, action); nft_gc_seq_end(nft_net, gc_seq); + + WARN_ON_ONCE(!list_empty(&nft_net->commit_list)); + mutex_unlock(&nft_net->commit_mutex); return ret; @@ -11473,9 +11477,10 @@ static void __net_exit nf_tables_exit_net(struct net *net) 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); + WARN_ON_ONCE(!list_empty(&nft_net->commit_list)); + + if (!list_empty(&nft_net->module_list)) + nf_tables_module_autoload_cleanup(net); __nft_release_tables(net); From 0d459e2ffb541841714839e8228b845458ed3b27 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 28 Mar 2024 14:23:55 +0100 Subject: [PATCH 2/6] netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path The commit mutex should not be released during the critical section between nft_gc_seq_begin() and nft_gc_seq_end(), otherwise, async GC worker could collect expired objects and get the released commit lock within the same GC sequence. nf_tables_module_autoload() temporarily releases the mutex to load module dependencies, then it goes back to replay the transaction again. Move it at the end of the abort phase after nft_gc_seq_end() is called. Cc: stable@vger.kernel.org Fixes: 720344340fb9 ("netfilter: nf_tables: GC transaction race with abort path") Reported-by: Kuan-Ting Chen Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index ffcd3213c335..0d432d0674e1 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -10651,11 +10651,6 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action) nf_tables_abort_release(trans); } - if (action == NFNL_ABORT_AUTOLOAD) - nf_tables_module_autoload(net); - else - nf_tables_module_autoload_cleanup(net); - return err; } @@ -10672,6 +10667,14 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb, WARN_ON_ONCE(!list_empty(&nft_net->commit_list)); + /* module autoload needs to happen after GC sequence update because it + * temporarily releases and grabs mutex again. + */ + if (action == NFNL_ABORT_AUTOLOAD) + nf_tables_module_autoload(net); + else + nf_tables_module_autoload_cleanup(net); + mutex_unlock(&nft_net->commit_mutex); return ret; From 24cea9677025e0de419989ecb692acd4bb34cac2 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Tue, 2 Apr 2024 18:04:36 +0200 Subject: [PATCH 3/6] netfilter: nf_tables: flush pending destroy work before exit_net release Similar to 2c9f0293280e ("netfilter: nf_tables: flush pending destroy work before netlink notifier") to address a race between exit_net and the destroy workqueue. The trace below shows an element to be released via destroy workqueue while exit_net path (triggered via module removal) has already released the set that is used in such transaction. [ 1360.547789] BUG: KASAN: slab-use-after-free in nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.547861] Read of size 8 at addr ffff888140500cc0 by task kworker/4:1/152465 [ 1360.547870] CPU: 4 PID: 152465 Comm: kworker/4:1 Not tainted 6.8.0+ #359 [ 1360.547882] Workqueue: events nf_tables_trans_destroy_work [nf_tables] [ 1360.547984] Call Trace: [ 1360.547991] [ 1360.547998] dump_stack_lvl+0x53/0x70 [ 1360.548014] print_report+0xc4/0x610 [ 1360.548026] ? __virt_addr_valid+0xba/0x160 [ 1360.548040] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 1360.548054] ? nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.548176] kasan_report+0xae/0xe0 [ 1360.548189] ? nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.548312] nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.548447] ? __pfx_nf_tables_trans_destroy_work+0x10/0x10 [nf_tables] [ 1360.548577] ? _raw_spin_unlock_irq+0x18/0x30 [ 1360.548591] process_one_work+0x2f1/0x670 [ 1360.548610] worker_thread+0x4d3/0x760 [ 1360.548627] ? __pfx_worker_thread+0x10/0x10 [ 1360.548640] kthread+0x16b/0x1b0 [ 1360.548653] ? __pfx_kthread+0x10/0x10 [ 1360.548665] ret_from_fork+0x2f/0x50 [ 1360.548679] ? __pfx_kthread+0x10/0x10 [ 1360.548690] ret_from_fork_asm+0x1a/0x30 [ 1360.548707] [ 1360.548719] Allocated by task 192061: [ 1360.548726] kasan_save_stack+0x20/0x40 [ 1360.548739] kasan_save_track+0x14/0x30 [ 1360.548750] __kasan_kmalloc+0x8f/0xa0 [ 1360.548760] __kmalloc_node+0x1f1/0x450 [ 1360.548771] nf_tables_newset+0x10c7/0x1b50 [nf_tables] [ 1360.548883] nfnetlink_rcv_batch+0xbc4/0xdc0 [nfnetlink] [ 1360.548909] nfnetlink_rcv+0x1a8/0x1e0 [nfnetlink] [ 1360.548927] netlink_unicast+0x367/0x4f0 [ 1360.548935] netlink_sendmsg+0x34b/0x610 [ 1360.548944] ____sys_sendmsg+0x4d4/0x510 [ 1360.548953] ___sys_sendmsg+0xc9/0x120 [ 1360.548961] __sys_sendmsg+0xbe/0x140 [ 1360.548971] do_syscall_64+0x55/0x120 [ 1360.548982] entry_SYSCALL_64_after_hwframe+0x55/0x5d [ 1360.548994] Freed by task 192222: [ 1360.548999] kasan_save_stack+0x20/0x40 [ 1360.549009] kasan_save_track+0x14/0x30 [ 1360.549019] kasan_save_free_info+0x3b/0x60 [ 1360.549028] poison_slab_object+0x100/0x180 [ 1360.549036] __kasan_slab_free+0x14/0x30 [ 1360.549042] kfree+0xb6/0x260 [ 1360.549049] __nft_release_table+0x473/0x6a0 [nf_tables] [ 1360.549131] nf_tables_exit_net+0x170/0x240 [nf_tables] [ 1360.549221] ops_exit_list+0x50/0xa0 [ 1360.549229] free_exit_list+0x101/0x140 [ 1360.549236] unregister_pernet_operations+0x107/0x160 [ 1360.549245] unregister_pernet_subsys+0x1c/0x30 [ 1360.549254] nf_tables_module_exit+0x43/0x80 [nf_tables] [ 1360.549345] __do_sys_delete_module+0x253/0x370 [ 1360.549352] do_syscall_64+0x55/0x120 [ 1360.549360] entry_SYSCALL_64_after_hwframe+0x55/0x5d (gdb) list *__nft_release_table+0x473 0x1e033 is in __nft_release_table (net/netfilter/nf_tables_api.c:11354). 11349 list_for_each_entry_safe(flowtable, nf, &table->flowtables, list) { 11350 list_del(&flowtable->list); 11351 nft_use_dec(&table->use); 11352 nf_tables_flowtable_destroy(flowtable); 11353 } 11354 list_for_each_entry_safe(set, ns, &table->sets, list) { 11355 list_del(&set->list); 11356 nft_use_dec(&table->use); 11357 if (set->flags & (NFT_SET_MAP | NFT_SET_OBJECT)) 11358 nft_map_deactivate(&ctx, set); (gdb) [ 1360.549372] Last potentially related work creation: [ 1360.549376] kasan_save_stack+0x20/0x40 [ 1360.549384] __kasan_record_aux_stack+0x9b/0xb0 [ 1360.549392] __queue_work+0x3fb/0x780 [ 1360.549399] queue_work_on+0x4f/0x60 [ 1360.549407] nft_rhash_remove+0x33b/0x340 [nf_tables] [ 1360.549516] nf_tables_commit+0x1c6a/0x2620 [nf_tables] [ 1360.549625] nfnetlink_rcv_batch+0x728/0xdc0 [nfnetlink] [ 1360.549647] nfnetlink_rcv+0x1a8/0x1e0 [nfnetlink] [ 1360.549671] netlink_unicast+0x367/0x4f0 [ 1360.549680] netlink_sendmsg+0x34b/0x610 [ 1360.549690] ____sys_sendmsg+0x4d4/0x510 [ 1360.549697] ___sys_sendmsg+0xc9/0x120 [ 1360.549706] __sys_sendmsg+0xbe/0x140 [ 1360.549715] do_syscall_64+0x55/0x120 [ 1360.549725] entry_SYSCALL_64_after_hwframe+0x55/0x5d Fixes: 0935d5588400 ("netfilter: nf_tables: asynchronous release") Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 0d432d0674e1..17bf53cd0e84 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -11575,6 +11575,7 @@ static void __exit nf_tables_module_exit(void) unregister_netdevice_notifier(&nf_tables_flowtable_notifier); nft_chain_filter_fini(); nft_chain_route_fini(); + nf_tables_trans_destroy_flush_work(); unregister_pernet_subsys(&nf_tables_net_ops); cancel_work_sync(&trans_gc_work); cancel_work_sync(&trans_destroy_work); From 994209ddf4f430946f6247616b2e33d179243769 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Mon, 1 Apr 2024 00:33:02 +0200 Subject: [PATCH 4/6] netfilter: nf_tables: reject new basechain after table flag update When dormant flag is toggled, hooks are disabled in the commit phase by iterating over current chains in table (existing and new). The following configuration allows for an inconsistent state: add table x add chain x y { type filter hook input priority 0; } add table x { flags dormant; } add chain x w { type filter hook input priority 1; } which triggers the following warning when trying to unregister chain w which is already unregistered. [ 127.322252] WARNING: CPU: 7 PID: 1211 at net/netfilter/core.c:50 1 __nf_unregister_net_hook+0x21a/0x260 [...] [ 127.322519] Call Trace: [ 127.322521] [ 127.322524] ? __warn+0x9f/0x1a0 [ 127.322531] ? __nf_unregister_net_hook+0x21a/0x260 [ 127.322537] ? report_bug+0x1b1/0x1e0 [ 127.322545] ? handle_bug+0x3c/0x70 [ 127.322552] ? exc_invalid_op+0x17/0x40 [ 127.322556] ? asm_exc_invalid_op+0x1a/0x20 [ 127.322563] ? kasan_save_free_info+0x3b/0x60 [ 127.322570] ? __nf_unregister_net_hook+0x6a/0x260 [ 127.322577] ? __nf_unregister_net_hook+0x21a/0x260 [ 127.322583] ? __nf_unregister_net_hook+0x6a/0x260 [ 127.322590] ? __nf_tables_unregister_hook+0x8a/0xe0 [nf_tables] [ 127.322655] nft_table_disable+0x75/0xf0 [nf_tables] [ 127.322717] nf_tables_commit+0x2571/0x2620 [nf_tables] Fixes: 179d9ba5559a ("netfilter: nf_tables: fix table flag updates") Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 17bf53cd0e84..1eb51bf24fc2 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -2449,6 +2449,9 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask, struct nft_stats __percpu *stats = NULL; struct nft_chain_hook hook = {}; + if (table->flags & __NFT_TABLE_F_UPDATE) + return -EINVAL; + if (flags & NFT_CHAIN_BINDING) return -EOPNOTSUPP; From 24225011d81b471acc0e1e315b7d9905459a6304 Mon Sep 17 00:00:00 2001 From: Ziyang Xuan Date: Wed, 3 Apr 2024 15:22:04 +0800 Subject: [PATCH 5/6] netfilter: nf_tables: Fix potential data-race in __nft_flowtable_type_get() nft_unregister_flowtable_type() within nf_flow_inet_module_exit() can concurrent with __nft_flowtable_type_get() within nf_tables_newflowtable(). And thhere is not any protection when iterate over nf_tables_flowtables list in __nft_flowtable_type_get(). Therefore, there is pertential data-race of nf_tables_flowtables list entry. Use list_for_each_entry_rcu() to iterate over nf_tables_flowtables list in __nft_flowtable_type_get(), and use rcu_read_lock() in the caller nft_flowtable_type_get() to protect the entire type query process. Fixes: 3b49e2e94e6e ("netfilter: nf_tables: add flow table netlink frontend") Signed-off-by: Ziyang Xuan Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 1eb51bf24fc2..e02d0ae4f436 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -8296,11 +8296,12 @@ static int nft_flowtable_parse_hook(const struct nft_ctx *ctx, return err; } +/* call under rcu_read_lock */ static const struct nf_flowtable_type *__nft_flowtable_type_get(u8 family) { const struct nf_flowtable_type *type; - list_for_each_entry(type, &nf_tables_flowtables, list) { + list_for_each_entry_rcu(type, &nf_tables_flowtables, list) { if (family == type->family) return type; } @@ -8312,9 +8313,13 @@ nft_flowtable_type_get(struct net *net, u8 family) { const struct nf_flowtable_type *type; + rcu_read_lock(); type = __nft_flowtable_type_get(family); - if (type != NULL && try_module_get(type->owner)) + if (type != NULL && try_module_get(type->owner)) { + rcu_read_unlock(); return type; + } + rcu_read_unlock(); lockdep_nfnl_nft_mutex_not_held(); #ifdef CONFIG_MODULES From 1bc83a019bbe268be3526406245ec28c2458a518 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Wed, 3 Apr 2024 19:35:30 +0200 Subject: [PATCH 6/6] netfilter: nf_tables: discard table flag update with pending basechain deletion Hook unregistration is deferred to the commit phase, same occurs with hook updates triggered by the table dormant flag. When both commands are combined, this results in deleting a basechain while leaving its hook still registered in the core. Fixes: 179d9ba5559a ("netfilter: nf_tables: fix table flag updates") Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index e02d0ae4f436..d89d77946719 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -1209,10 +1209,11 @@ static bool nft_table_pending_update(const struct nft_ctx *ctx) return true; list_for_each_entry(trans, &nft_net->commit_list, list) { - if ((trans->msg_type == NFT_MSG_NEWCHAIN || - trans->msg_type == NFT_MSG_DELCHAIN) && - trans->ctx.table == ctx->table && - nft_trans_chain_update(trans)) + if (trans->ctx.table == ctx->table && + ((trans->msg_type == NFT_MSG_NEWCHAIN && + nft_trans_chain_update(trans)) || + (trans->msg_type == NFT_MSG_DELCHAIN && + nft_is_base_chain(trans->ctx.chain)))) return true; }