[PATCH net 0/3] wireguard fixes for 6.4.2/6.5-rc1

[PATCH net 0/3] wireguard fixes for 6.4.2/6.5-rc1

[Jason A. Donenfeld]

Hi Jakub,

Sorry to send these patches during the merge window, but they're net
fixes, not netdev enhancements, and while I'd ordinarily wait anyway,
I just got a first bug report for one of these fixes, which I originally
had thought was mostly unlikely. So please apply the following three
patches to net:

1) Make proper use of nr_cpu_ids with cpumask_next(), rather than
   awkwardly using modulo, to handle dynamic CPU topology changes.
   Linus noticed this a while ago and pointed it out, and today a user
   actually got hit by it.

2) Respect persistent keepalive and other staged packets when setting
   the private key after the interface is already up.

3) Use timer_delete_sync() instead of del_timer_sync(), per the
   documentation.

Thanks,
Jason

Jason A. Donenfeld (3):
  wireguard: queueing: use saner cpu selection wrapping
  wireguard: netlink: send staged packets when setting initial private
    key
  wireguard: timers: move to using timer_delete_sync

 drivers/net/wireguard/netlink.c            | 14 ++++++----
 drivers/net/wireguard/queueing.c           |  1 +
 drivers/net/wireguard/queueing.h           | 25 ++++++++----------
 drivers/net/wireguard/receive.c            |  2 +-
 drivers/net/wireguard/send.c               |  2 +-
 drivers/net/wireguard/timers.c             | 10 ++++----
 tools/testing/selftests/wireguard/netns.sh | 30 +++++++++++++++++++---
 7 files changed, 54 insertions(+), 30 deletions(-)

-- 
2.41.0

[PATCH net 1/3] wireguard: queueing: use saner cpu selection wrapping

[Jason A. Donenfeld]

Using `% nr_cpumask_bits` is slow and complicated, and not totally
robust toward dynamic changes to CPU topologies. Rather than storing the
next CPU in the round-robin, just store the last one, and also return
that value. This simplifies the loop drastically into a much more common
pattern.

Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Cc: stable@vger.kernel.org
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Manuel Leiner <manuel.leiner@gmx.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 drivers/net/wireguard/queueing.c |  1 +
 drivers/net/wireguard/queueing.h | 25 +++++++++++--------------
 drivers/net/wireguard/receive.c  |  2 +-
 drivers/net/wireguard/send.c     |  2 +-
 4 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireguard/queueing.c b/drivers/net/wireguard/queueing.c
index 8084e7408c0a..26d235d15235 100644
--- a/drivers/net/wireguard/queueing.c
+++ b/drivers/net/wireguard/queueing.c
@@ -28,6 +28,7 @@ int wg_packet_queue_init(struct crypt_queue *queue, work_func_t function,
 	int ret;
 
 	memset(queue, 0, sizeof(*queue));
+	queue->last_cpu = -1;
 	ret = ptr_ring_init(&queue->ring, len, GFP_KERNEL);
 	if (ret)
 		return ret;
diff --git a/drivers/net/wireguard/queueing.h b/drivers/net/wireguard/queueing.h
index 125284b346a7..1ea4f874e367 100644
--- a/drivers/net/wireguard/queueing.h
+++ b/drivers/net/wireguard/queueing.h
@@ -117,20 +117,17 @@ static inline int wg_cpumask_choose_online(int *stored_cpu, unsigned int id)
 	return cpu;
 }
 
-/* This function is racy, in the sense that next is unlocked, so it could return
- * the same CPU twice. A race-free version of this would be to instead store an
- * atomic sequence number, do an increment-and-return, and then iterate through
- * every possible CPU until we get to that index -- choose_cpu. However that's
- * a bit slower, and it doesn't seem like this potential race actually
- * introduces any performance loss, so we live with it.
+/* This function is racy, in the sense that it's called while last_cpu is
+ * unlocked, so it could return the same CPU twice. Adding locking or using
+ * atomic sequence numbers is slower though, and the consequences of racing are
+ * harmless, so live with it.
  */
-static inline int wg_cpumask_next_online(int *next)
+static inline int wg_cpumask_next_online(int *last_cpu)
 {
-	int cpu = *next;
-
-	while (unlikely(!cpumask_test_cpu(cpu, cpu_online_mask)))
-		cpu = cpumask_next(cpu, cpu_online_mask) % nr_cpumask_bits;
-	*next = cpumask_next(cpu, cpu_online_mask) % nr_cpumask_bits;
+	int cpu = cpumask_next(*last_cpu, cpu_online_mask);
+	if (cpu >= nr_cpu_ids)
+		cpu = cpumask_first(cpu_online_mask);
+	*last_cpu = cpu;
 	return cpu;
 }
 
@@ -159,7 +156,7 @@ static inline void wg_prev_queue_drop_peeked(struct prev_queue *queue)
 
 static inline int wg_queue_enqueue_per_device_and_peer(
 	struct crypt_queue *device_queue, struct prev_queue *peer_queue,
-	struct sk_buff *skb, struct workqueue_struct *wq, int *next_cpu)
+	struct sk_buff *skb, struct workqueue_struct *wq)
 {
 	int cpu;
 
@@ -173,7 +170,7 @@ static inline int wg_queue_enqueue_per_device_and_peer(
 	/* Then we queue it up in the device queue, which consumes the
 	 * packet as soon as it can.
 	 */
-	cpu = wg_cpumask_next_online(next_cpu);
+	cpu = wg_cpumask_next_online(&device_queue->last_cpu);
 	if (unlikely(ptr_ring_produce_bh(&device_queue->ring, skb)))
 		return -EPIPE;
 	queue_work_on(cpu, wq, &per_cpu_ptr(device_queue->worker, cpu)->work);
diff --git a/drivers/net/wireguard/receive.c b/drivers/net/wireguard/receive.c
index 7135d51d2d87..0b3f0c843550 100644
--- a/drivers/net/wireguard/receive.c
+++ b/drivers/net/wireguard/receive.c
@@ -524,7 +524,7 @@ static void wg_packet_consume_data(struct wg_device *wg, struct sk_buff *skb)
 		goto err;
 
 	ret = wg_queue_enqueue_per_device_and_peer(&wg->decrypt_queue, &peer->rx_queue, skb,
-						   wg->packet_crypt_wq, &wg->decrypt_queue.last_cpu);
+						   wg->packet_crypt_wq);
 	if (unlikely(ret == -EPIPE))
 		wg_queue_enqueue_per_peer_rx(skb, PACKET_STATE_DEAD);
 	if (likely(!ret || ret == -EPIPE)) {
diff --git a/drivers/net/wireguard/send.c b/drivers/net/wireguard/send.c
index 5368f7c35b4b..95c853b59e1d 100644
--- a/drivers/net/wireguard/send.c
+++ b/drivers/net/wireguard/send.c
@@ -318,7 +318,7 @@ static void wg_packet_create_data(struct wg_peer *peer, struct sk_buff *first)
 		goto err;
 
 	ret = wg_queue_enqueue_per_device_and_peer(&wg->encrypt_queue, &peer->tx_queue, first,
-						   wg->packet_crypt_wq, &wg->encrypt_queue.last_cpu);
+						   wg->packet_crypt_wq);
 	if (unlikely(ret == -EPIPE))
 		wg_queue_enqueue_per_peer_tx(first, PACKET_STATE_DEAD);
 err:
-- 
2.41.0

Re: [PATCH net 1/3] wireguard: queueing: use saner cpu selection wrapping

[Linus Torvalds]

On Sun, 2 Jul 2023 at 18:27, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> Using `% nr_cpumask_bits` is slow and complicated, and not totally
> robust toward dynamic changes to CPU topologies. Rather than storing the
> next CPU in the round-robin, just store the last one, and also return
> that value. This simplifies the loop drastically into a much more common
> pattern.
>
> Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
> Cc: stable@vger.kernel.org
> Reported-by: Linus Torvalds <torvalds@linux-foundation.org>

Heh, thank you. Your memory is better than mine. That "Reported-by"
mystified me, so I had to go search for it.

March is clearly too long ago for me to remember anything.

I'm like a goldfish.

              Linus

[PATCH net 2/3] wireguard: netlink: send staged packets when setting initial private key

[Jason A. Donenfeld]

Packets bound for peers can queue up prior to the device private key
being set. For example, if persistent keepalive is set, a packet is
queued up to be sent as soon as the device comes up. However, if the
private key hasn't been set yet, the handshake message never sends, and
no timer is armed to retry, since that would be pointless.

But, if a user later sets a private key, the expectation is that those
queued packets, such as a persistent keepalive, are actually sent. So
adjust the configuration logic to account for this edge case, and add a
test case to make sure this works.

Maxim noticed this with a wg-quick(8) config to the tune of:

    [Interface]
    PostUp = wg set %i private-key somefile

    [Peer]
    PublicKey = ...
    Endpoint = ...
    PersistentKeepalive = 25

Here, the private key gets set after the device comes up using a PostUp
script, triggering the bug.

Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Cc: stable@vger.kernel.org
Reported-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Tested-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Link: https://lore.kernel.org/wireguard/87fs7xtqrv.fsf@gmail.com/
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 drivers/net/wireguard/netlink.c            | 14 ++++++----
 tools/testing/selftests/wireguard/netns.sh | 30 +++++++++++++++++++---
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireguard/netlink.c b/drivers/net/wireguard/netlink.c
index 43c8c84e7ea8..6d1bd9f52d02 100644
--- a/drivers/net/wireguard/netlink.c
+++ b/drivers/net/wireguard/netlink.c
@@ -546,6 +546,7 @@ static int wg_set_device(struct sk_buff *skb, struct genl_info *info)
 		u8 *private_key = nla_data(info->attrs[WGDEVICE_A_PRIVATE_KEY]);
 		u8 public_key[NOISE_PUBLIC_KEY_LEN];
 		struct wg_peer *peer, *temp;
+		bool send_staged_packets;
 
 		if (!crypto_memneq(wg->static_identity.static_private,
 				   private_key, NOISE_PUBLIC_KEY_LEN))
@@ -564,14 +565,17 @@ static int wg_set_device(struct sk_buff *skb, struct genl_info *info)
 		}
 
 		down_write(&wg->static_identity.lock);
-		wg_noise_set_static_identity_private_key(&wg->static_identity,
-							 private_key);
-		list_for_each_entry_safe(peer, temp, &wg->peer_list,
-					 peer_list) {
+		send_staged_packets = !wg->static_identity.has_identity && netif_running(wg->dev);
+		wg_noise_set_static_identity_private_key(&wg->static_identity, private_key);
+		send_staged_packets = send_staged_packets && wg->static_identity.has_identity;
+
+		wg_cookie_checker_precompute_device_keys(&wg->cookie_checker);
+		list_for_each_entry_safe(peer, temp, &wg->peer_list, peer_list) {
 			wg_noise_precompute_static_static(peer);
 			wg_noise_expire_current_peer_keypairs(peer);
+			if (send_staged_packets)
+				wg_packet_send_staged_packets(peer);
 		}
-		wg_cookie_checker_precompute_device_keys(&wg->cookie_checker);
 		up_write(&wg->static_identity.lock);
 	}
 skip_set_private_key:
diff --git a/tools/testing/selftests/wireguard/netns.sh b/tools/testing/selftests/wireguard/netns.sh
index 69c7796c7ca9..405ff262ca93 100755
--- a/tools/testing/selftests/wireguard/netns.sh
+++ b/tools/testing/selftests/wireguard/netns.sh
@@ -514,10 +514,32 @@ n2 bash -c 'printf 0 > /proc/sys/net/ipv4/conf/all/rp_filter'
 n1 ping -W 1 -c 1 192.168.241.2
 [[ $(n2 wg show wg0 endpoints) == "$pub1	10.0.0.3:1" ]]
 
-ip1 link del veth1
-ip1 link del veth3
-ip1 link del wg0
-ip2 link del wg0
+ip1 link del dev veth3
+ip1 link del dev wg0
+ip2 link del dev wg0
+
+# Make sure persistent keep alives are sent when an adapter comes up
+ip1 link add dev wg0 type wireguard
+n1 wg set wg0 private-key <(echo "$key1") peer "$pub2" endpoint 10.0.0.1:1 persistent-keepalive 1
+read _ _ tx_bytes < <(n1 wg show wg0 transfer)
+[[ $tx_bytes -eq 0 ]]
+ip1 link set dev wg0 up
+read _ _ tx_bytes < <(n1 wg show wg0 transfer)
+[[ $tx_bytes -gt 0 ]]
+ip1 link del dev wg0
+# This should also happen even if the private key is set later
+ip1 link add dev wg0 type wireguard
+n1 wg set wg0 peer "$pub2" endpoint 10.0.0.1:1 persistent-keepalive 1
+read _ _ tx_bytes < <(n1 wg show wg0 transfer)
+[[ $tx_bytes -eq 0 ]]
+ip1 link set dev wg0 up
+read _ _ tx_bytes < <(n1 wg show wg0 transfer)
+[[ $tx_bytes -eq 0 ]]
+n1 wg set wg0 private-key <(echo "$key1")
+read _ _ tx_bytes < <(n1 wg show wg0 transfer)
+[[ $tx_bytes -gt 0 ]]
+ip1 link del dev veth1
+ip1 link del dev wg0
 
 # We test that Netlink/IPC is working properly by doing things that usually cause split responses
 ip0 link add dev wg0 type wireguard
-- 
2.41.0

[PATCH net 3/3] wireguard: timers: move to using timer_delete_sync

[Jason A. Donenfeld]

The documentation says that del_timer_sync is obsolete, and code should
use the equivalent timer_delete_sync instead, so switch to it.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 drivers/net/wireguard/timers.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireguard/timers.c b/drivers/net/wireguard/timers.c
index 53d8a57a0dfa..968bdb4df0b3 100644
--- a/drivers/net/wireguard/timers.c
+++ b/drivers/net/wireguard/timers.c
@@ -234,10 +234,10 @@ void wg_timers_init(struct wg_peer *peer)
 
 void wg_timers_stop(struct wg_peer *peer)
 {
-	del_timer_sync(&peer->timer_retransmit_handshake);
-	del_timer_sync(&peer->timer_send_keepalive);
-	del_timer_sync(&peer->timer_new_handshake);
-	del_timer_sync(&peer->timer_zero_key_material);
-	del_timer_sync(&peer->timer_persistent_keepalive);
+	timer_delete_sync(&peer->timer_retransmit_handshake);
+	timer_delete_sync(&peer->timer_send_keepalive);
+	timer_delete_sync(&peer->timer_new_handshake);
+	timer_delete_sync(&peer->timer_zero_key_material);
+	timer_delete_sync(&peer->timer_persistent_keepalive);
 	flush_work(&peer->clear_peer_work);
 }
-- 
2.41.0