[PATCH net 0/3] Netfilter fixes for net

[PATCH net 0/3] Netfilter fixes for net

[Pablo Neira Ayuso]

Hi,

The following patchset contains Netfilter fixes for net:

1) Fix deadlock in nfnetlink due to missing mutex release in error path,
   from Ziyang Xuan.

2) Clean up pending autoload module list from nf_tables_exit_net() path,
   from Shigeru Yoshida.

3) Fixes for the netfilter's reverse path selftest, from Phil Sutter.

All of these bugs have been around for several releases.

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git

Thanks.

----------------------------------------------------------------

The following changes since commit ce9e57feeed81d17d5e80ed86f516ff0d39c3867:

  drivers: net: xgene: disable napi when register irq failed in xgene_enet_open() (2022-11-08 15:15:55 +0100)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git HEAD

for you to fetch changes up to 58bb78ce02269c0cf5b1f2bd2e4a605500b44c6b:

  selftests: netfilter: Fix and review rpath.sh (2022-11-09 10:29:57 +0100)

----------------------------------------------------------------
Phil Sutter (1):
      selftests: netfilter: Fix and review rpath.sh

Shigeru Yoshida (1):
      netfilter: Cleanup nft_net->module_list from nf_tables_exit_net()

Ziyang Xuan (1):
      netfilter: nfnetlink: fix potential dead lock in nfnetlink_rcv_msg()

 net/netfilter/nf_tables_api.c              |  3 ++-
 net/netfilter/nfnetlink.c                  |  1 +
 tools/testing/selftests/netfilter/rpath.sh | 14 ++++++++------
 3 files changed, 11 insertions(+), 7 deletions(-)

[PATCH net 1/3] netfilter: nfnetlink: fix potential dead lock in nfnetlink_rcv_msg()

[Pablo Neira Ayuso]

From: Ziyang Xuan <william.xuanziyang@huawei.com>

When type is NFNL_CB_MUTEX and -EAGAIN error occur in nfnetlink_rcv_msg(),
it does not execute nfnl_unlock(). That would trigger potential dead lock.

Fixes: 50f2db9e368f ("netfilter: nfnetlink: consolidate callback types")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nfnetlink.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 9c44518cb70f..6d18fb346868 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -294,6 +294,7 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 			nfnl_lock(subsys_id);
 			if (nfnl_dereference_protected(subsys_id) != ss ||
 			    nfnetlink_find_client(type, ss) != nc) {
+				nfnl_unlock(subsys_id);
 				err = -EAGAIN;
 				break;
 			}
-- 
2.30.2

[PATCH net 2/3] netfilter: Cleanup nft_net->module_list from nf_tables_exit_net()

[Pablo Neira Ayuso]

From: Shigeru Yoshida <syoshida@redhat.com>

syzbot reported a warning like below [1]:

WARNING: CPU: 3 PID: 9 at net/netfilter/nf_tables_api.c:10096 nf_tables_exit_net+0x71c/0x840
Modules linked in:
CPU: 2 PID: 9 Comm: kworker/u8:0 Tainted: G        W          6.1.0-rc3-00072-g8e5423e991e8 #47
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:nf_tables_exit_net+0x71c/0x840
...
Call Trace:
 <TASK>
 ? __nft_release_table+0xfc0/0xfc0
 ops_exit_list+0xb5/0x180
 cleanup_net+0x506/0xb10
 ? unregister_pernet_device+0x80/0x80
 process_one_work+0xa38/0x1730
 ? pwq_dec_nr_in_flight+0x2b0/0x2b0
 ? rwlock_bug.part.0+0x90/0x90
 ? _raw_spin_lock_irq+0x46/0x50
 worker_thread+0x67e/0x10e0
 ? process_one_work+0x1730/0x1730
 kthread+0x2e5/0x3a0
 ? kthread_complete_and_exit+0x40/0x40
 ret_from_fork+0x1f/0x30
 </TASK>

In nf_tables_exit_net(), there is a case where nft_net->commit_list is
empty but nft_net->module_list is not empty.  Such a case occurs with
the following scenario:

1. nfnetlink_rcv_batch() is called
2. nf_tables_newset() returns -EAGAIN and NFNL_BATCH_FAILURE bit is
   set to status
3. nf_tables_abort() is called with NFNL_ABORT_AUTOLOAD
   (nft_net->commit_list is released, but nft_net->module_list is not
   because of NFNL_ABORT_AUTOLOAD flag)
4. Jump to replay label
5. netlink_skb_clone() fails and returns from the function (this is
   caused by fault injection in the reproducer of syzbot)

This patch fixes this issue by calling __nf_tables_abort() when
nft_net->module_list is not empty in nf_tables_exit_net().

Fixes: eb014de4fd41 ("netfilter: nf_tables: autoload modules from the abort path")
Link: https://syzkaller.appspot.com/bug?id=802aba2422de4218ad0c01b46c9525cc9d4e4aa3 [1]
Reported-by: syzbot+178efee9e2d7f87f5103@syzkaller.appspotmail.com
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nf_tables_api.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 76bd4d03dbda..e7152d599d73 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -10090,7 +10090,8 @@ static void __net_exit nf_tables_exit_net(struct net *net)
 	struct nftables_pernet *nft_net = nft_pernet(net);
 
 	mutex_lock(&nft_net->commit_mutex);
-	if (!list_empty(&nft_net->commit_list))
+	if (!list_empty(&nft_net->commit_list) ||
+	    !list_empty(&nft_net->module_list))
 		__nf_tables_abort(net, NFNL_ABORT_NONE);
 	__nft_release_tables(net);
 	mutex_unlock(&nft_net->commit_mutex);
-- 
2.30.2

[PATCH net 3/3] selftests: netfilter: Fix and review rpath.sh

[Pablo Neira Ayuso]

From: Phil Sutter <phil@nwl.cc>

Address a few problems with the initial test script version:

* On systems with ip6tables but no ip6tables-legacy, testing for
  ip6tables was disabled by accident.
* Firewall setup phase did not respect possibly unavailable tools.
* Consistently call nft via '$nft'.

Fixes: 6e31ce831c63b ("selftests: netfilter: Test reverse path filtering")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 tools/testing/selftests/netfilter/rpath.sh | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/netfilter/rpath.sh b/tools/testing/selftests/netfilter/rpath.sh
index 2d8da7bd8ab7..f7311e66d219 100755
--- a/tools/testing/selftests/netfilter/rpath.sh
+++ b/tools/testing/selftests/netfilter/rpath.sh
@@ -15,7 +15,7 @@ fi
 
 if ip6tables-legacy --version >/dev/null 2>&1; then
 	ip6tables='ip6tables-legacy'
-elif ! ip6tables --version >/dev/null 2>&1; then
+elif ip6tables --version >/dev/null 2>&1; then
 	ip6tables='ip6tables'
 else
 	ip6tables=''
@@ -62,9 +62,11 @@ ip -net "$ns1" a a fec0:42::2/64 dev v0 nodad
 ip -net "$ns2" a a fec0:42::1/64 dev d0 nodad
 
 # firewall matches to test
-ip netns exec "$ns2" "$iptables" -t raw -A PREROUTING -s 192.168.0.0/16 -m rpfilter
-ip netns exec "$ns2" "$ip6tables" -t raw -A PREROUTING -s fec0::/16 -m rpfilter
-ip netns exec "$ns2" nft -f - <<EOF
+[ -n "$iptables" ] && ip netns exec "$ns2" \
+	"$iptables" -t raw -A PREROUTING -s 192.168.0.0/16 -m rpfilter
+[ -n "$ip6tables" ] && ip netns exec "$ns2" \
+	"$ip6tables" -t raw -A PREROUTING -s fec0::/16 -m rpfilter
+[ -n "$nft" ] && ip netns exec "$ns2" $nft -f - <<EOF
 table inet t {
 	chain c {
 		type filter hook prerouting priority raw;
@@ -106,8 +108,8 @@ testrun() {
 	if [ -n "$nft" ]; then
 		(
 			echo "delete table inet t";
-			ip netns exec "$ns2" nft -s list table inet t;
-		) | ip netns exec "$ns2" nft -f -
+			ip netns exec "$ns2" $nft -s list table inet t;
+		) | ip netns exec "$ns2" $nft -f -
 	fi
 
 	# test 1: martian traffic should fail rpfilter matches
-- 
2.30.2

Re: [PATCH net 1/3] netfilter: nfnetlink: fix potential dead lock in nfnetlink_rcv_msg()

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by Pablo Neira Ayuso <pablo@netfilter.org>:

On Wed,  9 Nov 2022 12:28:18 +0100 you wrote:
> From: Ziyang Xuan <william.xuanziyang@huawei.com>
> 
> When type is NFNL_CB_MUTEX and -EAGAIN error occur in nfnetlink_rcv_msg(),
> it does not execute nfnl_unlock(). That would trigger potential dead lock.
> 
> Fixes: 50f2db9e368f ("netfilter: nfnetlink: consolidate callback types")
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> 
> [...]

Here is the summary with links:
  - [net,1/3] netfilter: nfnetlink: fix potential dead lock in nfnetlink_rcv_msg()
    https://git.kernel.org/netdev/net/c/03832a32bf8f
  - [net,2/3] netfilter: Cleanup nft_net->module_list from nf_tables_exit_net()
    https://git.kernel.org/netdev/net/c/03c1f1ef1584
  - [net,3/3] selftests: netfilter: Fix and review rpath.sh
    https://git.kernel.org/netdev/net/c/58bb78ce0226

You are awesome, thank you!
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