From 65ab9de4bdd4c05d8277cfc20ae0b9f5aff60897 Mon Sep 17 00:00:00 2001 From: Ramses de Norre Date: Thu, 8 Oct 2026 14:59:15 +0200 Subject: [PATCH 1/2] wireguard: queueing: preserve tstamp_type when encapsulating packet MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sending traffic through a wireguard tunnel on a host using the fq qdisc fills the log with: fq: likely mono tstamp with tstamp_type 0 An skb carries a timestamp in skb->tstamp and, separately, a skb->tstamp_type field recording which clock that timestamp came from. The two have to agree. When wireguard encapsulates a packet it calls wg_reset_packet(), which clears the fields that must not leak from the inner packet into the tunnel packet. It does so in two steps: skb_scrub_packet(skb, true); memset(&skb->headers, 0, sizeof(skb->headers)); skb_scrub_packet() deliberately keeps skb->tstamp when it holds a monotonic timestamp: that value is the time the packet is scheduled to be sent, and the qdisc still needs it. The memset then zeroes skb->tstamp_type, because that field sits inside the headers group while skb->tstamp does not. The packet therefore leaves wireguard carrying a monotonic timestamp labelled as a realtime one. Nothing noticed until commit c4f796c4f16b ("net_sched: sch_fq: convert skb->tstamp if not monotonic"): fq used to assume every timestamp was monotonic. It now consults tstamp_type, spots the mismatch, warns, and falls back to treating the value as monotonic. Pacing still ends up correct, so the log spam is the actual problem. Save tstamp_type before the memset and restore it when encapsulating, next to the hash fields that are already carried over this way. When decapsulating it stays zeroed, which is right: an incoming packet's timestamp is a realtime receive timestamp. Fixes: d98d58a00261 ("net: Set skb->mono_delivery_time and clear it after sch_handle_ingress()") Signed-off-by: Ramses de Norre Reviewed-by: Toke Høiland-Jørgensen Reviewed-by: Eric Dumazet Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld Link: https://patch.msgid.link/20261008130124.724119-3-Jason@zx2c4.com Signed-off-by: Jakub Kicinski --- drivers/net/wireguard/queueing.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/wireguard/queueing.h b/drivers/net/wireguard/queueing.h index 79b6d70de236..663b19b78395 100644 --- a/drivers/net/wireguard/queueing.h +++ b/drivers/net/wireguard/queueing.h @@ -78,12 +78,14 @@ static inline void wg_reset_packet(struct sk_buff *skb, bool encapsulating) u8 l4_hash = skb->l4_hash; u8 sw_hash = skb->sw_hash; u32 hash = skb->hash; + u8 tstamp_type = skb->tstamp_type; skb_scrub_packet(skb, true); memset(&skb->headers, 0, sizeof(skb->headers)); if (encapsulating) { skb->l4_hash = l4_hash; skb->sw_hash = sw_hash; skb->hash = hash; + skb->tstamp_type = tstamp_type; } skb->queue_mapping = 0; skb->nohdr = 0; From d0305f8d90029556260c6824b61c493c424eba9e Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 8 Oct 2026 14:59:16 +0200 Subject: [PATCH 2/2] wireguard: noise: reject response consumption after intermediate initiation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Two threads begin processing the identical response message, received twice. The first thread, A, runs. While it's running, the second one, B, gets partway through, and during that slow calculation, or even while blocking on down_write(), A completes and then also a handshake initiation that's already been queued up runs in thread C, which itself takes that same down_write(). The handshake initiation creation succeeds, and sets the state back to waiting-for-response, and calls up_write(), at which point thread B resumes, because either its finished its calculations or was finally allowed to acquire down_write(). Thread B then copies the state back to the peer, and begins a new session, using that state, which is the same session as the one made in thread A. Thread A Thread B Thread C down_read() sA = handshake->state memcpy(cA, handshake->crypto) up_read() if (sA != 1) goto fail slow_crypto(cA) down_read() sB = handshake->state memcpy(cB, handshake->crypto) up_read() if (sB != 1) goto fail slow_crypto(cB) down_write() if (sA != handshake->state) goto fail memcpy(handshake->crypto, cA) handshake->state = 2 up_write() down_write() if (handshake->state != 2) goto fail derive_session(handshake->crypto) up_write() down_write() slow_crypto(handshake->crypto) handshake->state = 1 up_write() down_write() if (sB != handshake->state) goto fail memcpy(handshake->crypto, cB) handshake->state = 2 up_write() down_write() if (handshake->state != 2) goto fail derive_session(handshake->crypto) up_write() This seems basically impossible to hit in a meaningful way in practice, but ensure that it absolutely cannot happen by comparing the ephemeral private key that's on the stack with the latest one that the peer's handshake state has. Cc: stable@vger.kernel.org Fixes: e7096c131e51 ("net: WireGuard secure network tunnel") Reported-by: Jérémy Jean Signed-off-by: Jason A. Donenfeld Link: https://patch.msgid.link/20261008130124.724119-4-Jason@zx2c4.com Signed-off-by: Jakub Kicinski --- drivers/net/wireguard/noise.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/net/wireguard/noise.c b/drivers/net/wireguard/noise.c index 9c0a09bf6c95..ec2513d6dfab 100644 --- a/drivers/net/wireguard/noise.c +++ b/drivers/net/wireguard/noise.c @@ -784,10 +784,11 @@ wg_noise_handshake_consume_response(struct message_handshake_response *src, /* Success! Copy everything to peer */ down_write(&handshake->lock); - /* It's important to check that the state is still the same, while we - * have an exclusive lock. + /* Check that the state is the same and that this is still the + * initiation we started with, while we have an exclusive lock. */ - if (handshake->state != state) { + if (handshake->state != state || + crypto_memneq(handshake->ephemeral_private, ephemeral_private, NOISE_PUBLIC_KEY_LEN)) { up_write(&handshake->lock); goto fail; }