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AJvYcCUo10sbkxODmH0wNtVKeSB8yWpqJYZaMlQPVDCwVEGJxDZ/f82RvfJ+bIeMTgqUjIANSN4K@lists.linux.dev X-Gm-Message-State: AOJu0YzjTEtu6rIKxHS81LqVRhNpnCrxV4La+DJl7v0WSdCwta34+jjj eL+K1HJD8BTXZVHy7SO94F0NxIZl3vtjXpYA+AtZSv4pob+O4+VTXzTSqYGjmfIrMXtTFCtYiG/ gSL1irWCiS0lZ/lRiFnFn6dxm3xYrYjs= X-Gm-Gg: AZuq6aIR5Kxd8eDRgwLmVw5hWAMkdTL9iPjvvhqUaQ/7anEZO4KNE25fp366TJ3TctT rG2MECPC0Fj8a+aJihH36r3iDmxCZabWrF1blA7cGiiMC70gIHVYWhBFi+N8RUL5swamHQwVIdo V1yKfSY+ABxiVDeqmIeydD5/QWhykBx0NY8MOB1n72q465kPIqPK8YPn+lQCUhuu0zzDnJ1IfMt yvQHqUhl3NXbCbea/Vmz4OagsCoZ/x85QJrlcM/mZDw5cZFsnM92QHRuSsqt6vW6EJekB43DAwu oiim+/aCBhDkLx1cpsyaMmfdCWqt X-Received: by 2002:a17:90a:dfcd:b0:352:d59a:b28 with SMTP id 98e67ed59e1d1-354b3cae091mr42496a91.19.1770318190665; Thu, 05 Feb 2026 11:03:10 -0800 (PST) Precedence: bulk X-Mailing-List: quic@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <431335747d3604c46f2e57a32d839a73aa8a8536.1770042461.git.lucien.xin@gmail.com> <20260205115542.2195362-1-horms@kernel.org> In-Reply-To: <20260205115542.2195362-1-horms@kernel.org> From: Xin Long Date: Thu, 5 Feb 2026 14:02:58 -0500 X-Gm-Features: AZwV_QhI8OwuLRWeiqC_GNUtx69lACcTHyYZmGGt6r8v7RB2RzBMyspqQrCybPk Message-ID: Subject: Re: [net-next,v9,15/15] quic: add packet parser base To: Simon Horman 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, Feb 5, 2026 at 6:55=E2=80=AFAM Simon Horman wrot= e: > > 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-loca= l.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 =3D 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 =3D uh->source; > sa->v4.sin_addr.s_addr =3D ip_hdr(skb)->saddr; > da->v4.sin_port =3D uh->dest; > da->v4.sin_addr.s_addr =3D 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 bein= g > 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 cas= e. */ Thanks.