Re: [PATCH net-next 5/7] phonet: pep: convert getsockopt to sockopt_t

[David Laight <david.laight.linux@gmail.com>]

On Thu, 16 Jul 2026 06:00:03 -0700
Breno Leitao <leitao@debian.org> wrote:

> Continue converting the proto-layer getsockopt callbacks to the
> sockopt_t interface, splitting pep_getsockopt() into a
> do_pep_getsockopt() helper that takes a sockopt_t.
> 
> The thin pep_getsockopt() wrapper keeps its __user signature for now:
> it builds a user-backed sockopt_t with sockopt_init_user(), calls the
> helper, and writes the returned length back to optlen. The helper uses
> copy_to_iter() instead of copy_to_user(). No functional change.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  net/phonet/pep.c | 36 ++++++++++++++++++++++++++----------
>  1 file changed, 26 insertions(+), 10 deletions(-)
> 
> diff --git a/net/phonet/pep.c b/net/phonet/pep.c
> index 60d1a5375725b..c7f4ce894af56 100644
> --- a/net/phonet/pep.c
> +++ b/net/phonet/pep.c
> @@ -1078,17 +1078,11 @@ static int pep_setsockopt(struct sock *sk, int level, int optname,
>  	return err;
>  }
>  
> -static int pep_getsockopt(struct sock *sk, int level, int optname,
> -				char __user *optval, int __user *optlen)
> +static int do_pep_getsockopt(struct sock *sk, int optname, sockopt_t *opt)
>  {
>  	struct pep_sock *pn = pep_sk(sk);
>  	int len, val;
>  
> -	if (level != SOL_PNPIPE)
> -		return -ENOPROTOOPT;
> -	if (get_user(len, optlen))
> -		return -EFAULT;
> -
>  	switch (optname) {
>  	case PNPIPE_ENCAP:
>  		val = pn->ifindex ? PNPIPE_ENCAP_IP : PNPIPE_ENCAP_NONE;
> @@ -1112,11 +1106,33 @@ static int pep_getsockopt(struct sock *sk, int level, int optname,
>  		return -ENOPROTOOPT;
>  	}
>  
> -	len = min_t(unsigned int, sizeof(int), len);
> -	if (put_user(len, optlen))
> +	len = min_t(unsigned int, sizeof(int), opt->optlen);

I'm pretty sure that can be min().
More generally I'm not at all sure about negative lengths.
Historically the user type would have been 'int', but it got replaced
by socklen_t which is probably unsigned.
(IIRC one of the 64bit Unix had started using a 64bit type but I think
it was sun objected to making that change so socklen_t was born.)

Also truncating below 4 bytes makes no sense here on BE systems.
Some code will try to write the significant bytes out, but that
would be better done in the wrapper.

> +	opt->optlen = len;
> +	if (copy_to_iter(&val, len, &opt->iter_out) != len)
>  		return -EFAULT;
> -	if (copy_to_user(optval, &val, len))
> +	return 0;
> +}
> +
> +static int pep_getsockopt(struct sock *sk, int level, int optname,
> +			  char __user *optval, int __user *optlen)
> +{
> +	sockopt_t opt;
> +	int err;
> +
> +	if (level != SOL_PNPIPE)
> +		return -ENOPROTOOPT;
> +
> +	err = sockopt_init_user(&opt, optval, optlen);

Have I not looked at these before?
Why is this here, not in the outer code?

	David

> +	if (err)
> +		return err;
> +
> +	err = do_pep_getsockopt(sk, optname, &opt);
> +	if (err)
> +		return err;
> +
> +	if (put_user(opt.optlen, optlen))
>  		return -EFAULT;
> +
>  	return 0;
>  }
>  
>