From: Xin Long <lucien.xin@gmail.com>
To: Simon Horman <horms@kernel.org>
Cc: steved@redhat.com, marcelo.leitner@gmail.com,
aahringo@redhat.com, alibuda@linux.alibaba.com,
jbaron@akamai.com, hare@suse.de, kuba@kernel.org,
tom@talpey.com, linux-cifs@vger.kernel.org, daniel@haxx.se,
quic@lists.linux.dev, jlayton@kernel.org, tfanelli@redhat.com,
dhowells@redhat.com, linkinjeon@kernel.org,
hepengtao@xiaomi.com, pc@manguebit.com,
kernel-tls-handshake@lists.linux.dev, illiliti@protonmail.com,
xiyou.wangcong@gmail.com, andrew.gospodarek@broadcom.com,
mail@johnericson.me, edumazet@google.com, pabeni@redhat.com,
matttbe@kernel.org, netdev@vger.kernel.org, smfrench@gmail.com,
metze@samba.org, mbuhl@openbsd.org, chuck.lever@oracle.com,
dreibh@simula.no, davem@davemloft.net, sd@queasysnail.net
Subject: Re: [net-next,v9,15/15] quic: add packet parser base
Date: Thu, 5 Feb 2026 14:02:58 -0500 [thread overview]
Message-ID: <CADvbK_e8Sbm8Q3KVR=uZZDYuQLTdprRskN=jgompaSeYDkmhFw@mail.gmail.com> (raw)
In-Reply-To: <20260205115542.2195362-1-horms@kernel.org>
On Thu, Feb 5, 2026 at 6:55 AM Simon Horman <horms@kernel.org> wrote:
>
> This is an AI-generated review of your patch. The human sending this
> email has considered the AI review valid, or at least plausible.
>
> For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
> ---
> quic: add packet parser base
>
> This patch uses 'quic_packet' to handle packing of QUIC packets on the
> receive (RX) path. It introduces mechanisms to parse the ALPN from client
> Initial packets to determine the correct listener socket, routes received
> packets accordingly, and adds support for ICMP-based MTU updates by
> locating the relevant socket and updating the stored PMTU.
>
> > diff --git a/net/quic/packet.c b/net/quic/packet.c
> > index cf64a6aaa795..16a7db6ccd87 100644
> > --- a/net/quic/packet.c
> > +++ b/net/quic/packet.c
>
> [ ... ]
>
> > @@ -14,6 +14,637 @@
> >
> > #define QUIC_HLEN 1
> >
> > +/* Handle ICMP Toobig packet and update QUIC socket path MTU. */
> > +static int quic_packet_rcv_err(struct sock *sk, struct sk_buff *skb)
> > +{
> > + union quic_addr daddr, saddr;
> > + u32 info;
> > +
> > + /* All we can do is lookup the matching QUIC socket by addresses. */
> > + quic_get_msg_addrs(skb, &saddr, &daddr);
> > + sk = quic_sock_lookup(skb, &daddr, &saddr, sk, NULL);
>
> Are the address arguments swapped in quic_packet_rcv_err()? Looking at
> other call sites in this file, quic_get_msg_addrs is consistently called
> with &daddr first, then &saddr:
>
> Line 476 in quic_packet_get_listen_sock():
> quic_get_msg_addrs(skb, &daddr, &saddr);
>
> Line 513 in quic_packet_get_sock():
> quic_get_msg_addrs(skb, &daddr, &saddr);
>
> Line 536 in quic_packet_get_sock():
> quic_get_msg_addrs(skb, &daddr, &saddr);
>
> But here quic_packet_rcv_err() passes &saddr first, then &daddr.
>
> Looking at the implementation of quic_v4_get_msg_addrs() in
> net/quic/family.c, the function extracts addresses from the packet as:
>
> sa->v4.sin_port = uh->source;
> sa->v4.sin_addr.s_addr = ip_hdr(skb)->saddr;
> da->v4.sin_port = uh->dest;
> da->v4.sin_addr.s_addr = ip_hdr(skb)->daddr;
>
> So sa gets the packet's source address (remote), and da gets the packet's
> destination address (local).
>
> Then quic_sock_lookup() in net/quic/socket.c expects:
>
> if (quic_cmp_sk_addr(tmp, quic_path_saddr(paths, 0), sa) &&
> quic_cmp_sk_addr(tmp, quic_path_daddr(paths, 0), da) &&
>
> This compares the socket's local address with sa and the socket's remote
> address with da, meaning sa should be the local (packet dest) address and
> da should be the remote (packet source) address.
>
> With the swapped arguments, quic_packet_rcv_err() would pass the remote
> address where the local is expected and vice versa, causing the socket
> lookup to fail. This would prevent ICMP Packet Too Big messages from being
> processed correctly, breaking Path MTU Discovery.
>
The code is correct, I may add a comment for the explanation:
/* ICMP embeds the original outgoing QUIC packet, so
saddr/daddr are reversed when
* parsed. Only address-based socket lookup is possible in this case.
*/
Thanks.
prev parent reply other threads:[~2026-02-05 19:03 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-02 14:27 [PATCH net-next v9 00/15] net: introduce QUIC infrastructure and core subcomponents Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 01/15] net: define IPPROTO_QUIC and SOL_QUIC constants Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 02/15] net: build socket infrastructure for QUIC protocol Xin Long
2026-02-05 11:54 ` [net-next,v9,02/15] " Simon Horman
2026-02-05 12:48 ` Paolo Abeni
2026-02-05 19:03 ` Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 03/15] quic: provide common utilities and data structures Xin Long
2026-02-05 11:54 ` [net-next,v9,03/15] " Simon Horman
2026-02-05 12:51 ` Paolo Abeni
2026-02-05 19:18 ` Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 04/15] quic: provide family ops for address and protocol Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 05/15] quic: provide quic.h header files for kernel and userspace Xin Long
2026-02-05 11:55 ` [net-next,v9,05/15] " Simon Horman
2026-02-05 19:37 ` Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 06/15] quic: add stream management Xin Long
2026-02-05 11:55 ` [net-next,v9,06/15] " Simon Horman
2026-02-05 18:56 ` Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 07/15] quic: add connection id management Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 08/15] quic: add path management Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 09/15] quic: add congestion control Xin Long
2026-02-05 11:55 ` [net-next,v9,09/15] " Simon Horman
2026-02-05 19:00 ` Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 10/15] quic: add packet number space Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 11/15] quic: add crypto key derivation and installation Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 12/15] quic: add crypto packet encryption and decryption Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 13/15] quic: add timer management Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 14/15] quic: add packet builder base Xin Long
2026-02-02 14:27 ` [PATCH net-next v9 15/15] quic: add packet parser base Xin Long
2026-02-05 11:55 ` [net-next,v9,15/15] " Simon Horman
2026-02-05 19:02 ` Xin Long [this message]
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