Re: [PATCH net-next v5] net: ioctl: Use kernel memory on protocol ioctl callbacks

Breno Leitao
2023-06-04T07:59:43Z

Hello Willem

On Sat, Jun 03, 2023 at 10:21:50AM +0200, Willem de Bruijn wrote:
> On Fri, Jun 2, 2023 at 6:31 PM Breno Leitao <leitao@debian.org> wrote:
> > Signed-off-by: Breno Leitao <leitao@debian.org>
>
> Please check the checkpatch output
>
> https://patchwork.hopto.org/static/nipa/753609/13265673/checkpatch/stdout

I am checking my current checkpatch before sending the patch, but I am
not seeing the problems above.

My tree is at 44c026a73be8038 ("Linux 6.4-rc3"), and I am not able to
reproduce the problems above.

$ scripts/checkpatch.pl v5/v5-0001-net-ioctl-Use-kernel-memory-on-protocol-ioctl-cal.patch
total: 0 errors, 0 warnings, 0 checks, 806 lines checked
v5/v5-0001-net-ioctl-Use-kernel-memory-on-protocol-ioctl-cal.patch has no obvious style problems and is ready for submission.

Let me investigate what options I am missing when running checkpatch.

> > +/* A wrapper around sock ioctls, which copies the data from userspace
> > + * (depending on the protocol/ioctl), and copies back the result to userspace.
> > + * The main motivation for this function is to pass kernel memory to the
> > + * protocol ioctl callbacks, instead of userspace memory.
> > + */
> > +int sk_ioctl(struct sock *sk, unsigned int cmd, void __user *arg)
> > +{
> > + int rc = 1;
> > +
> > + if (sk_is_ipmr(sk))
> > + rc = ipmr_sk_ioctl(sk, cmd, arg);
> > + else if (sk_is_icmpv6(sk))
> > + rc = ip6mr_sk_ioctl(sk, cmd, arg);
> > + else if (sk_is_phonet(sk))
> > + rc = phonet_sk_ioctl(sk, cmd, arg);
>
> Does this handle all phonet ioctl cases correctly?
>
> Notably pn_socket_ioctl has a SIOCPNGETOBJECT that reads and writes a u16.

We are not touching "struct proto_ops" in this patch at all. And
pn_socket_ioctl() is part of "struct proto_ops".

const struct proto_ops phonet_stream_ops = {
...
.ioctl = pn_socket_ioctl,
}

That said, all the "struct proto_ops" ioctl calls backs continue to use
"unsigned long arg" with userspace information, at least for now.

struct proto_ops {
...
int (*ioctl) (struct socket *sock, unsigned int cmd,
unsigned long arg);
}

This patch only changes the "struct proto".