Re: [PATCH net-next v3 02/15] net: build socket infrastructure for QUIC protocol

[Paolo Abeni <pabeni@redhat.com>]

On 9/19/25 12:34 AM, Xin Long wrote:
> This patch lays the groundwork for QUIC socket support in the kernel.
> It defines the core structures and protocol hooks needed to create
> QUIC sockets, without implementing any protocol behavior at this stage.
> 
> Basic integration is included to allow building the module via
> CONFIG_IP_QUIC=m.
> 
> This provides the scaffolding necessary for adding actual QUIC socket
> behavior in follow-up patches.
> 
> Signed-off-by: Pengtao He <hepengtao@xiaomi.com>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---
> v3:
>   - Kconfig: add 'default n' for IP_QUIC (reported by Paolo).
>   - quic_disconnect(): return -EOPNOTSUPP (suggested by Paolo).
>   - quic_init/destroy_sock(): drop local_bh_disable/enable() calls (noted
>     by Paolo).
>   - sysctl: add alpn_demux option to en/disable ALPN-based demux.
>   - SNMP: remove SNMP_MIB_SENTINEL, switch to
>     snmp_get_cpu_field_batch_cnt() to align with latest net-next changes.
> ---
>  net/Kconfig         |   1 +
>  net/Makefile        |   1 +
>  net/quic/Kconfig    |  36 +++++
>  net/quic/Makefile   |   8 +
>  net/quic/protocol.c | 379 ++++++++++++++++++++++++++++++++++++++++++++
>  net/quic/protocol.h |  56 +++++++
>  net/quic/socket.c   | 207 ++++++++++++++++++++++++
>  net/quic/socket.h   |  79 +++++++++
>  8 files changed, 767 insertions(+)
>  create mode 100644 net/quic/Kconfig
>  create mode 100644 net/quic/Makefile
>  create mode 100644 net/quic/protocol.c
>  create mode 100644 net/quic/protocol.h
>  create mode 100644 net/quic/socket.c
>  create mode 100644 net/quic/socket.h
> 
> diff --git a/net/Kconfig b/net/Kconfig
> index d5865cf19799..1205f5b7cf59 100644
> --- a/net/Kconfig
> +++ b/net/Kconfig
> @@ -249,6 +249,7 @@ source "net/bridge/netfilter/Kconfig"
>  
>  endif # if NETFILTER
>  
> +source "net/quic/Kconfig"
>  source "net/sctp/Kconfig"
>  source "net/rds/Kconfig"
>  source "net/tipc/Kconfig"
> diff --git a/net/Makefile b/net/Makefile
> index aac960c41db6..7c6de28e9aa5 100644
> --- a/net/Makefile
> +++ b/net/Makefile
> @@ -42,6 +42,7 @@ obj-$(CONFIG_PHONET)		+= phonet/
>  ifneq ($(CONFIG_VLAN_8021Q),)
>  obj-y				+= 8021q/
>  endif
> +obj-$(CONFIG_IP_QUIC)		+= quic/
>  obj-$(CONFIG_IP_SCTP)		+= sctp/
>  obj-$(CONFIG_RDS)		+= rds/
>  obj-$(CONFIG_WIRELESS)		+= wireless/
> diff --git a/net/quic/Kconfig b/net/quic/Kconfig
> new file mode 100644
> index 000000000000..1f10a452b3a1
> --- /dev/null
> +++ b/net/quic/Kconfig
> @@ -0,0 +1,36 @@
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +#
> +# QUIC configuration
> +#
> +
> +menuconfig IP_QUIC
> +	tristate "QUIC: A UDP-Based Multiplexed and Secure Transport (Experimental)"
> +	depends on INET
> +	depends on IPV6
> +	select CRYPTO
> +	select CRYPTO_HMAC
> +	select CRYPTO_HKDF
> +	select CRYPTO_AES
> +	select CRYPTO_GCM
> +	select CRYPTO_CCM
> +	select CRYPTO_CHACHA20POLY1305
> +	select NET_UDP_TUNNEL
> +	default n
> +	help
> +	  QUIC: A UDP-Based Multiplexed and Secure Transport
> +
> +	  From rfc9000 <https://www.rfc-editor.org/rfc/rfc9000.html>.
> +
> +	  QUIC provides applications with flow-controlled streams for structured
> +	  communication, low-latency connection establishment, and network path
> +	  migration.  QUIC includes security measures that ensure
> +	  confidentiality, integrity, and availability in a range of deployment
> +	  circumstances.  Accompanying documents describe the integration of
> +	  TLS for key negotiation, loss detection, and an exemplary congestion
> +	  control algorithm.
> +
> +	  To compile this protocol support as a module, choose M here: the
> +	  module will be called quic. Debug messages are handled by the
> +	  kernel's dynamic debugging framework.
> +
> +	  If in doubt, say N.
> diff --git a/net/quic/Makefile b/net/quic/Makefile
> new file mode 100644
> index 000000000000..020e4dd133d8
> --- /dev/null
> +++ b/net/quic/Makefile
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +#
> +# Makefile for QUIC support code.
> +#
> +
> +obj-$(CONFIG_IP_QUIC) += quic.o
> +
> +quic-y := protocol.o socket.o
> diff --git a/net/quic/protocol.c b/net/quic/protocol.c
> new file mode 100644
> index 000000000000..f79f43f0c17f
> --- /dev/null
> +++ b/net/quic/protocol.c
> @@ -0,0 +1,379 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/* QUIC kernel implementation
> + * (C) Copyright Red Hat Corp. 2023
> + *
> + * This file is part of the QUIC kernel implementation
> + *
> + * Initialization/cleanup for QUIC protocol support.
> + *
> + * Written or modified by:
> + *    Xin Long <lucien.xin@gmail.com>
> + */
> +
> +#include <net/inet_common.h>
> +#include <linux/proc_fs.h>
> +#include <net/protocol.h>
> +#include <net/rps.h>
> +#include <net/tls.h>
> +
> +#include "socket.h"
> +
> +static unsigned int quic_net_id __read_mostly;
> +
> +struct percpu_counter quic_sockets_allocated;
> +
> +long sysctl_quic_mem[3];
> +int sysctl_quic_rmem[3];
> +int sysctl_quic_wmem[3];
> +int sysctl_quic_alpn_demux;
> +
> +static int quic_inet_connect(struct socket *sock, struct sockaddr *addr, int addr_len, int flags)
> +{
> +	struct sock *sk = sock->sk;
> +	const struct proto *prot;
> +
> +	if (addr_len < (int)sizeof(addr->sa_family))
> +		return -EINVAL;
> +
> +	prot = READ_ONCE(sk->sk_prot);

Is the above _ONCE() annotation for ADDRFORM's sake? If so it should not
be needed (only UDP and TCP sockets are affected).

> diff --git a/net/quic/socket.h b/net/quic/socket.h
> new file mode 100644
> index 000000000000..ded8eb2e6a9c
> --- /dev/null
> +++ b/net/quic/socket.h
> @@ -0,0 +1,79 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/* QUIC kernel implementation
> + * (C) Copyright Red Hat Corp. 2023
> + *
> + * This file is part of the QUIC kernel implementation
> + *
> + * Written or modified by:
> + *    Xin Long <lucien.xin@gmail.com>
> + */
> +
> +#include <net/udp_tunnel.h>
> +
> +#include "protocol.h"
> +
> +extern struct proto quic_prot;
> +extern struct proto quicv6_prot;
> +
> +enum quic_state {
> +	QUIC_SS_CLOSED		= TCP_CLOSE,
> +	QUIC_SS_LISTENING	= TCP_LISTEN,
> +	QUIC_SS_ESTABLISHING	= TCP_SYN_RECV,
> +	QUIC_SS_ESTABLISHED	= TCP_ESTABLISHED,
> +};

Any special reason to define protocol-specific states? I guess you could
re-use the TCP ones, as other protocols already do.

/P