Re: [PATCH] allow UDP cmsghdrs through io_uring

[Victor Stewart <v@nametag.social>]

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
>