[PATCH v2] Allow UDP cmsghdrs through io_uring

[PATCH v2] Allow UDP cmsghdrs through io_uring

[Victor Stewart]

This patch adds PROTO_CMSG_DATA_ONLY to inet_dgram_ops and inet6_dgram_ops so that UDP_SEGMENT (GSO) and UDP_GRO can be used through io_uring.

GSO and GRO are vital to bring QUIC servers on par with TCP throughputs, and together offer a higher
throughput gain than io_uring alone (rate of data transit
considering), thus io_uring is presently the lesser performance choice.

RE http://vger.kernel.org/lpc_net2018_talks/willemdebruijn-lpc2018-udpgso-paper-DRAFT-1.pdf,
GSO is about +~63% and GRO +~82%.

this patch closes that loophole. 

net/ipv4/af_inet.c  | 1 +
net/ipv6/af_inet6.c | 1 +
net/socket.c        | 8 +++++---
3 files changed, 7 insertions(+), 3 deletions(-)

[PATCH] allow UDP cmsghdrs through io_uring

[Victor Stewart]

---
 net/ipv4/af_inet.c  | 1 +
 net/ipv6/af_inet6.c | 1 +
 net/socket.c        | 8 +++++---
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index b7260c8cef2e..c9fd5e7cfd6e 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1052,6 +1052,7 @@ EXPORT_SYMBOL(inet_stream_ops);
 
 const struct proto_ops inet_dgram_ops = {
 	.family		   = PF_INET,
+	.flags		   = PROTO_CMSG_DATA_ONLY,
 	.owner		   = THIS_MODULE,
 	.release	   = inet_release,
 	.bind		   = inet_bind,
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index e648fbebb167..560f45009d06 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -695,6 +695,7 @@ const struct proto_ops inet6_stream_ops = {
 
 const struct proto_ops inet6_dgram_ops = {
 	.family		   = PF_INET6,
+	.flags		   = PROTO_CMSG_DATA_ONLY,
 	.owner		   = THIS_MODULE,
 	.release	   = inet6_release,
 	.bind		   = inet6_bind,
diff --git a/net/socket.c b/net/socket.c
index 6e6cccc2104f..6995835d6355 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2416,9 +2416,11 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
 long __sys_sendmsg_sock(struct socket *sock, struct msghdr *msg,
 			unsigned int flags)
 {
-	/* disallow ancillary data requests from this path */
-	if (msg->msg_control || msg->msg_controllen)
-		return -EINVAL;
+	if (msg->msg_control || msg->msg_controllen) {
+		/* disallow ancillary data reqs unless cmsg is plain data */
+		if (!(sock->ops->flags & PROTO_CMSG_DATA_ONLY))
+			return -EINVAL;
+	}
 
 	return ____sys_sendmsg(sock, msg, flags, NULL, 0);
 }
-- 
2.26.2

Re: [PATCH] allow UDP cmsghdrs through io_uring

[Victor Stewart]

the header didn't come through on my email, but i see it in the
archive. almost got this git send-email thing working lol. the patch
got a different subject line for some reason.

On Sun, Dec 13, 2020 at 8:31 PM Victor Stewart <v@nametag.social> wrote:
>
> ---
>  net/ipv4/af_inet.c  | 1 +
>  net/ipv6/af_inet6.c | 1 +
>  net/socket.c        | 8 +++++---
>  3 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index b7260c8cef2e..c9fd5e7cfd6e 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1052,6 +1052,7 @@ EXPORT_SYMBOL(inet_stream_ops);
>
>  const struct proto_ops inet_dgram_ops = {
>         .family            = PF_INET,
> +       .flags             = PROTO_CMSG_DATA_ONLY,
>         .owner             = THIS_MODULE,
>         .release           = inet_release,
>         .bind              = inet_bind,
> diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
> index e648fbebb167..560f45009d06 100644
> --- a/net/ipv6/af_inet6.c
> +++ b/net/ipv6/af_inet6.c
> @@ -695,6 +695,7 @@ const struct proto_ops inet6_stream_ops = {
>
>  const struct proto_ops inet6_dgram_ops = {
>         .family            = PF_INET6,
> +       .flags             = PROTO_CMSG_DATA_ONLY,
>         .owner             = THIS_MODULE,
>         .release           = inet6_release,
>         .bind              = inet6_bind,
> diff --git a/net/socket.c b/net/socket.c
> index 6e6cccc2104f..6995835d6355 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -2416,9 +2416,11 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
>  long __sys_sendmsg_sock(struct socket *sock, struct msghdr *msg,
>                         unsigned int flags)
>  {
> -       /* disallow ancillary data requests from this path */
> -       if (msg->msg_control || msg->msg_controllen)
> -               return -EINVAL;
> +       if (msg->msg_control || msg->msg_controllen) {
> +               /* disallow ancillary data reqs unless cmsg is plain data */
> +               if (!(sock->ops->flags & PROTO_CMSG_DATA_ONLY))
> +                       return -EINVAL;
> +       }
>
>         return ____sys_sendmsg(sock, msg, flags, NULL, 0);
>  }
> --
> 2.26.2
>