Re: [Qemu-devel] [PATCH 1/4] qemu-user: Impl. setsockopt(SO_BINDTODEVICE)

[Peter Maydell]

On 11 July 2014 16:18, Joakim Tjernlund <address@hidden> wrote:
> Signed-off-by: Joakim Tjernlund <address@hidden>
> ---
>  linux-user/syscall.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 5a272d3..1380f4e 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1497,6 +1497,18 @@ set_timeout:
>                  unlock_user_struct(tfprog, optval_addr, 1);
>                  return ret;
>          }
> +       case TARGET_SO_BINDTODEVICE:
> +       {
> +               char *dev_ifname;
> +
> +               if (optlen > IFNAMSIZ)
> +                       return -TARGET_EINVAL;

This needs braces for our coding style; you might like
to run your patches through scripts/checkpatch.pl, which
will warn about this kind of thing.

Also, the kernel implementation handles overlong
lengths via
     if (optlen > IFNAMSIZ - 1) {
         optlen = IFNAMSIZ - 1;
     }

which effectively truncates overlong strings rather
than rejecting them. We should do the same (there will
be complication required to ensure we pass the kernel
a NUL-terminated string even if we don't get one from
the guest; may be easiest to use a local array, given
IFNAMSIZ is only 16).

> +
> +               dev_ifname = lock_user(VERIFY_READ, optval_addr, optlen, 1);
> +               ret = get_errno(setsockopt(sockfd, level, optname, 
> dev_ifname, optlen));

This is passing the target optname through to the
host kernel; you need to set 'optname = SO_BINDTODEVICE;'
(look at the other cases in this switch).

> +               unlock_user (dev_ifname, optval_addr, 0);
> +               return ret;
> +       }
>              /* Options with 'int' argument.  */
>          case TARGET_SO_DEBUG:
>                 optname = SO_DEBUG;
> --
> 1.8.5.5

thanks
-- PMM