Re: [Qemu-devel] [PATCH v12 1/5] linux-user: Add support for setsockopt() options IPV6_<ADD|DROP>_MEMBERSHIP

[Laurent Vivier]

Le 19/06/2019 à 16:17, Aleksandar Markovic a écrit :
> From: Neng Chen <address@hidden>
> 
> Add support for the option IPV6_<ADD|DROP>_MEMBERSHIP of the syscall
> setsockopt(). This option controls membership in multicast groups.
> Argument is a pointer to a struct ipv6_mreq.
> 
> The glibc <netinet/in.h> header defines the ipv6_mreq structure,
> which includes the following members:
> 
>   struct in6_addr  ipv6mr_multiaddr;
>   unsigned int     ipv6mr_interface;
> 
> Whereas the kernel in its <linux/in6.h> header defines following
> members of the same structure:
> 
>   struct in6_addr  ipv6mr_multiaddr;
>   int              ipv6mr_ifindex;
> 
> POSIX defines ipv6mr_interface [1].
> 
> __UAPI_DEF_IVP6_MREQ appears in kernel headers with v3.12:
> 
>   cfd280c91253 net: sync some IP headers with glibc
> 
> Without __UAPI_DEF_IVP6_MREQ, kernel defines ipv6mr_ifindex, and
> this is explained in cfd280c91253:
> 
>   "If you include the kernel headers first you get those,
>   and if you include the glibc headers first you get those,
>   and the following patch arranges a coordination and
>   synchronization between the two."
> 
> So before 3.12, a program can't include both <netinet/in.h> and
> <linux/in6.h>.
> 
> In linux-user/syscall.c, we only include <netinet/in.h> (glibc) and
> not <linux/in6.h> (kernel headers), so ipv6mr_interface is the one
> to use.
> 
> [1] http://pubs.opengroup.org/onlinepubs/009695399/basedefs/netinet/in.h.html
> 
> Signed-off-by: Neng Chen <address@hidden>
> Signed-off-by: Aleksandar Markovic <address@hidden>
> ---
>  linux-user/syscall.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index b187c12..f267ad0 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1920,6 +1920,25 @@ static abi_long do_setsockopt(int sockfd, int level, 
> int optname,
>                                         &pki, sizeof(pki)));
>              break;
>          }
> +        case IPV6_ADD_MEMBERSHIP:
> +        case IPV6_DROP_MEMBERSHIP:
> +        {
> +            struct ipv6_mreq ipv6mreq;
> +
> +            if (optlen < sizeof(ipv6mreq)) {
> +                return -TARGET_EINVAL;
> +            }
> +
> +            if (copy_from_user(&ipv6mreq, optval_addr, sizeof(ipv6mreq))) {
> +                return -TARGET_EFAULT;
> +            }
> +
> +            ipv6mreq.ipv6mr_interface = tswap32(ipv6mreq.ipv6mr_interface);
> +
> +            ret = get_errno(setsockopt(sockfd, level, optname,
> +                                       &ipv6mreq, sizeof(ipv6mreq)));
> +            break;
> +        }
>          default:
>              goto unimplemented;
>          }
> 

Reviewed-by: Laurent Vivier <address@hidden>