Re: [PATCH net-next 4/6] l2tp: ppp: convert to getsockopt_iter

On 05/13, Breno Leitao wrote:
> Convert PPPoL2TP socket's getsockopt implementation to use the new
> getsockopt_iter callback with sockopt_t.
> 
> Key changes:
> - Replace (char __user *optval, int __user *optlen) with sockopt_t *opt
> - Use opt->optlen for buffer length (input) and returned size (output)
> - Use copy_to_iter() instead of put_user()/copy_to_user()
> 
> Signed-off-by: Breno Leitao <[email protected]>
> ---
>  net/l2tp/l2tp_ppp.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
> index 99d6582f41de2..4c7a1152b20ba 100644
> --- a/net/l2tp/l2tp_ppp.c
> +++ b/net/l2tp/l2tp_ppp.c
> @@ -59,6 +59,7 @@
>  #include <linux/string.h>
>  #include <linux/list.h>
>  #include <linux/uaccess.h>
> +#include <linux/uio.h>
>  
>  #include <linux/kernel.h>
>  #include <linux/spinlock.h>
> @@ -1317,7 +1318,7 @@ static int pppol2tp_session_getsockopt(struct sock *sk,
>   * or the special tunnel type.
>   */
>  static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
> -			       char __user *optval, int __user *optlen)
> +			       sockopt_t *opt)
>  {
>  	struct sock *sk = sock->sk;
>  	struct l2tp_session *session;
> @@ -1328,9 +1329,7 @@ static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
>  	if (level != SOL_PPPOL2TP)
>  		return -EINVAL;
>  
> -	if (get_user(len, optlen))
> -		return -EFAULT;
> -
> +	len = opt->optlen;
>  	if (len < 0)
>  		return -EINVAL;
>  
> @@ -1358,12 +1357,11 @@ static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
>  			goto end_put_sess;
>  	}
>  
> -	err = -EFAULT;
> -	if (put_user(len, optlen))
> -		goto end_put_sess;
> -
> -	if (copy_to_user((void __user *)optval, &val, len))
> +	opt->optlen = len;
> +	if (copy_to_iter(&val, len, &opt->iter_out) != len) {
> +		err = -EFAULT;
>  		goto end_put_sess;
> +	}
>  
>  	err = 0;

nit: if you're moving `err = -EFAULT`, you might as well remove this
`err = 0` ?

Acked-by: Stanislav Fomichev <[email protected]>