[PATCH -stable,5.10.x 0/3] Netfilter fixes for -stable

[PATCH -stable,5.10.x 0/3] Netfilter fixes for -stable

[Pablo Neira Ayuso]

Hi Greg, Sasha,

This batch contains a backport for recent fixes already upstream for 5.10.x,
to add them on top of your enqueued patches:

994209ddf4f4 ("netfilter: nf_tables: reject new basechain after table flag update")
24cea9677025 ("netfilter: nf_tables: flush pending destroy work before exit_net release")
a45e6889575c ("netfilter: nf_tables: release batch on table validation from abort path")
0d459e2ffb54 ("netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path")
1bc83a019bbe ("netfilter: nf_tables: discard table flag update with pending basechain deletion")

Please, apply, thanks.

Pablo Neira Ayuso (5):
  netfilter: nf_tables: reject new basechain after table flag update
  netfilter: nf_tables: flush pending destroy work before exit_net release
  netfilter: nf_tables: release batch on table validation from abort path
  netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path
  netfilter: nf_tables: discard table flag update with pending basechain deletion

 net/netfilter/nf_tables_api.c | 51 ++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 10 deletions(-)

-- 
2.30.2

[PATCH 1/5] netfilter: nf_tables: reject new basechain after table flag update

[Pablo Neira Ayuso]

commit 994209ddf4f430946f6247616b2e33d179243769 upstream.

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]  <TASK>
[  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 <pablo@netfilter.org>
---
 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 8d4472b127e4..fe7b66e04bdc 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2225,6 +2225,9 @@ 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;
 
-- 
2.30.2

[PATCH 2/5] netfilter: nf_tables: flush pending destroy work before exit_net release

[Pablo Neira Ayuso]

commit 24cea9677025e0de419989ecb692acd4bb34cac2 upstream.

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]  <TASK>
[ 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]  </TASK>

[ 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 <pablo@netfilter.org>
---
 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 fe7b66e04bdc..b6ad46e59ae1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9782,6 +9782,7 @@ 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);
-- 
2.30.2

[PATCH 3/5] netfilter: nf_tables: release batch on table validation from abort path

[Pablo Neira Ayuso]

commit a45e6889575c2067d3c0212b6bc1022891e65b91 upstream.

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 <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index b6ad46e59ae1..23ca5c249d0c 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8781,10 +8781,11 @@ 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) {
@@ -8949,7 +8950,7 @@ 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,
@@ -8963,6 +8964,8 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb,
 	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;
@@ -9697,8 +9700,11 @@ 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))
-		__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);
 
 	nft_gc_seq_end(nft_net, gc_seq);
-- 
2.30.2

[PATCH 4/5] netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path

[Pablo Neira Ayuso]

commit 0d459e2ffb541841714839e8228b845458ed3b27 upstream.

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 <hexrabbit@devco.re>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 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 23ca5c249d0c..12dab452f133 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8945,11 +8945,6 @@ 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;
 }
 
@@ -8966,6 +8961,14 @@ 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;
-- 
2.30.2

[PATCH 5/5] netfilter: nf_tables: discard table flag update with pending basechain deletion

[Pablo Neira Ayuso]

commit 1bc83a019bbe268be3526406245ec28c2458a518 upstream.

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 <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 12dab452f133..b17e3ee6b1c1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1084,6 +1084,24 @@ static void nf_tables_table_disable(struct net *net, struct nft_table *table)
 #define __NFT_TABLE_F_UPDATE		(__NFT_TABLE_F_WAS_DORMANT | \
 					 __NFT_TABLE_F_WAS_AWAKEN)
 
+static bool nft_table_pending_update(const struct nft_ctx *ctx)
+{
+	struct nftables_pernet *nft_net = net_generic(ctx->net, nf_tables_net_id);
+	struct nft_trans *trans;
+
+	if (ctx->table->flags & __NFT_TABLE_F_UPDATE)
+		return true;
+
+	list_for_each_entry(trans, &nft_net->commit_list, list) {
+		if (trans->ctx.table == ctx->table &&
+		    trans->msg_type == NFT_MSG_DELCHAIN &&
+		    nft_is_base_chain(trans->ctx.chain))
+			return true;
+	}
+
+	return false;
+}
+
 static int nf_tables_updtable(struct nft_ctx *ctx)
 {
 	struct nft_trans *trans;
@@ -1101,7 +1119,7 @@ static int nf_tables_updtable(struct nft_ctx *ctx)
 		return 0;
 
 	/* No dormant off/on/off/on games in single transaction */
-	if (ctx->table->flags & __NFT_TABLE_F_UPDATE)
+	if (nft_table_pending_update(ctx))
 		return -EINVAL;
 
 	trans = nft_trans_alloc(ctx, NFT_MSG_NEWTABLE,
-- 
2.30.2

Re: [PATCH -stable,5.10.x 0/3] Netfilter fixes for -stable

[Pablo Neira Ayuso]

On Mon, Apr 08, 2024 at 11:20:37PM +0200, Pablo Neira Ayuso wrote:
> Hi Greg, Sasha,
> 
> This batch contains a backport for recent fixes already upstream for 5.10.x,
> to add them on top of your enqueued patches:
> 
> 994209ddf4f4 ("netfilter: nf_tables: reject new basechain after table flag update")
> 24cea9677025 ("netfilter: nf_tables: flush pending destroy work before exit_net release")
> a45e6889575c ("netfilter: nf_tables: release batch on table validation from abort path")
> 0d459e2ffb54 ("netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path")
> 1bc83a019bbe ("netfilter: nf_tables: discard table flag update with pending basechain deletion")

Side note: this batch indeed contains 5 patches, subject should be:

        [PATCH -stable,5.10.x 0/5] Netfilter fixes for -stable

I can resend if needed.

> Please, apply, thanks.
> 
> Pablo Neira Ayuso (5):
>   netfilter: nf_tables: reject new basechain after table flag update
>   netfilter: nf_tables: flush pending destroy work before exit_net release
>   netfilter: nf_tables: release batch on table validation from abort path
>   netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path
>   netfilter: nf_tables: discard table flag update with pending basechain deletion
> 
>  net/netfilter/nf_tables_api.c | 51 ++++++++++++++++++++++++++++-------
>  1 file changed, 41 insertions(+), 10 deletions(-)
> 
> -- 
> 2.30.2
> 
>