From: Frédéric Lécaille <flecaille@haproxy.com>
Date: Thu, 16 Feb 2023 10:40:11 +0000 (+0100)
Subject: BUG/MINOR: quic: Do not drop too small datagrams with Initial packets
X-Git-Tag: v2.8-dev5~171
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=35218c6357b441142b2af19e31c8991a28b97075;p=thirdparty%2Fhaproxy.git

BUG/MINOR: quic: Do not drop too small datagrams with Initial packets

When receiving an Initial packet a peer must drop it if the datagram is smaller
than 1200. Before this patch, this is the entire datagram which was dropped.

In such a case, drop the packet after having parsed its length.

Must be backported to 2.6 and 2.7
---

diff --git a/src/quic_conn.c b/src/quic_conn.c
index ebbf003cba..83188c4282 100644
--- a/src/quic_conn.c
+++ b/src/quic_conn.c
@@ -6287,13 +6287,6 @@ static int quic_rx_pkt_parse(struct quic_rx_packet *pkt,
 			goto drop;
 		}
 
-		if (pkt->type == QUIC_PACKET_TYPE_INITIAL &&
-		    dgram->len < QUIC_INITIAL_PACKET_MINLEN) {
-			TRACE_PROTO("Too short datagram with an Initial packet", QUIC_EV_CONN_LPKT);
-			HA_ATOMIC_INC(&prx_counters->too_short_initial_dgram);
-			goto drop;
-		}
-
 		/* When multiple QUIC packets are coalesced on the same UDP datagram,
 		 * they must have the same DCID.
 		 */
@@ -6388,6 +6381,19 @@ static int quic_rx_pkt_parse(struct quic_rx_packet *pkt,
 		pkt->pn_offset = buf - beg;
 		pkt->len = pkt->pn_offset + len;
 
+		/* RFC 9000. Initial Datagram Size
+		 *
+		 * A server MUST discard an Initial packet that is carried in a UDP datagram
+		 * with a payload that is smaller than the smallest allowed maximum datagram
+		 * size of 1200 bytes.
+		 */
+		if (pkt->type == QUIC_PACKET_TYPE_INITIAL &&
+		    dgram->len < QUIC_INITIAL_PACKET_MINLEN) {
+			TRACE_PROTO("Too short datagram with an Initial packet", QUIC_EV_CONN_LPKT);
+			HA_ATOMIC_INC(&prx_counters->too_short_initial_dgram);
+			goto drop;
+		}
+
 		/* Interrupt parsing after packet length retrieval : this
 		 * ensures that only the packet is dropped but not the whole
 		 * datagram.