[PATCH net-next v3 01/15] net: define IPPROTO_QUIC and SOL_QUIC constants

Xin Long
2025-09-18T22:39:07Z

This patch adds IPPROTO_QUIC and SOL_QUIC constants to the networking
subsystem. These definitions are essential for applications to set
socket options and protocol identifiers related to the QUIC protocol.

QUIC does not possess a protocol number allocated from IANA, and like
IPPROTO_MPTCP, IPPROTO_QUIC is merely a value used when opening a QUIC
socket with:

socket(AF_INET, SOCK_STREAM, IPPROTO_QUIC);

Note we did not opt for UDP ULP for QUIC implementation due to several
considerations:

- QUIC's connection Migration requires at least 2 UDP sockets for one
QUIC connection at the same time, not to mention the multipath
feature in one of its draft RFCs.

- In-Kernel QUIC, as a Transport Protocol, wants to provide users with
the TCP or SCTP like Socket APIs, like connect()/listen()/accept()...
Note that a single UDP socket might even be used for multiple QUIC
connections.

The use of IPPROTO_QUIC type sockets over UDP tunnel will effectively
address these challenges and provides a more flexible and scalable
solution.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
include/linux/socket.h | 1 +
include/uapi/linux/in.h | 2 ++
2 files changed, 3 insertions(+)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 3b262487ec06..a7c05b064583 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -386,6 +386,7 @@ struct ucred {
#define SOL_MCTP 285
#define SOL_SMC 286
#define SOL_VSOCK 287
+#define SOL_QUIC 288

/* IPX options */
#define IPX_TYPE 1
diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h
index ced0fc3c3aa5..34becd90d3a6 100644
--- a/include/uapi/linux/in.h
+++ b/include/uapi/linux/in.h
@@ -85,6 +85,8 @@ enum {
#define IPPROTO_RAW IPPROTO_RAW
IPPROTO_SMC = 256, /* Shared Memory Communications */
#define IPPROTO_SMC IPPROTO_SMC
+ IPPROTO_QUIC = 261, /* A UDP-Based Multiplexed and Secure Transport */
+#define IPPROTO_QUIC IPPROTO_QUIC
IPPROTO_MPTCP = 262, /* Multipath TCP connection */
#define IPPROTO_MPTCP IPPROTO_MPTCP
IPPROTO_MAX
--
2.47.1