Re: [PULL v2 01/13] linux-user: Support for NETLINK socket options

[Peter Maydell <peter.maydell@linaro.org>]

On Wed, 6 Nov 2019 at 13:07, Laurent Vivier <laurent@vivier.eu> wrote:
>
> From: Josh Kunz <jkz@google.com>
>
> This change includes support for all AF_NETLINK socket options up to about
> kernel version 5.4 (5.4 is not formally released at the time of writing).
> Socket options that were introduced in kernel versions before the oldest
> currently stable kernel version are guarded by kernel version macros.
>
> This change has been built under gcc 8.3, and clang 9.0, and it passes
> `make check`. The netlink options have been tested by emulating some
> non-trival software that uses NETLINK socket options, but they have
> not been exaustively verified.

Hi; Coverity reports a missing-break-in-switch error for
this commit (CID 1407221):

> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index f6751eecb78c..247883292ce5 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -2248,6 +2248,39 @@ set_timeout:
>              return -TARGET_EFAULT;
>         ret = get_errno(setsockopt(sockfd, SOL_SOCKET, optname, &val, sizeof(val)));
>          break;
> +#ifdef SOL_NETLINK
> +    case SOL_NETLINK:
> +        switch (optname) {
> +        case NETLINK_PKTINFO:
> +        case NETLINK_ADD_MEMBERSHIP:
> +        case NETLINK_DROP_MEMBERSHIP:
> +        case NETLINK_BROADCAST_ERROR:
> +        case NETLINK_NO_ENOBUFS:
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
> +        case NETLINK_LISTEN_ALL_NSID:
> +        case NETLINK_CAP_ACK:
> +#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0) */
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 12, 0)
> +        case NETLINK_EXT_ACK:
> +#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 12, 0) */
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 20, 0)
> +        case NETLINK_GET_STRICT_CHK:
> +#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 12, 0) */
> +            break;
> +        default:
> +            goto unimplemented;
> +        }
> +        val = 0;
> +        if (optlen < sizeof(uint32_t)) {
> +            return -TARGET_EINVAL;
> +        }
> +        if (get_user_u32(val, optval_addr)) {
> +            return -TARGET_EFAULT;
> +        }
> +        ret = get_errno(setsockopt(sockfd, SOL_NETLINK, optname, &val,
> +                                   sizeof(val)));
> +        break;
> +#endif /* SOL_NETLINK */
>      default:
>      unimplemented:
>          gemu_log("Unsupported setsockopt level=%d optname=%d\n", level, optname);
> @@ -2532,6 +2565,74 @@ static abi_long do_getsockopt(int sockfd, int level, int optname,
>              break;
>          }
>          break;
> +#ifdef SOL_NETLINK
> +    case SOL_NETLINK:
> +        switch (optname) {
> +        case NETLINK_PKTINFO:
> +        case NETLINK_BROADCAST_ERROR:
> +        case NETLINK_NO_ENOBUFS:
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
> +        case NETLINK_LISTEN_ALL_NSID:
> +        case NETLINK_CAP_ACK:
> +#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0) */
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 12, 0)
> +        case NETLINK_EXT_ACK:
> +#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 12, 0) */
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 20, 0)
> +        case NETLINK_GET_STRICT_CHK:
> +#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 12, 0) */
> +            if (get_user_u32(len, optlen)) {
> +                return -TARGET_EFAULT;
> +            }
> +            if (len != sizeof(val)) {
> +                return -TARGET_EINVAL;
> +            }
> +            lv = len;
> +            ret = get_errno(getsockopt(sockfd, level, optname, &val, &lv));
> +            if (ret < 0) {
> +                return ret;
> +            }
> +            if (put_user_u32(lv, optlen)
> +                || put_user_u32(val, optval_addr)) {
> +                return -TARGET_EFAULT;
> +            }
> +            break;
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
> +        case NETLINK_LIST_MEMBERSHIPS:
> +        {
> +            uint32_t *results;
> +            int i;
> +            if (get_user_u32(len, optlen)) {
> +                return -TARGET_EFAULT;
> +            }
> +            if (len < 0) {
> +                return -TARGET_EINVAL;
> +            }
> +            results = lock_user(VERIFY_WRITE, optval_addr, len, 1);
> +            if (!results) {
> +                return -TARGET_EFAULT;
> +            }
> +            lv = len;
> +            ret = get_errno(getsockopt(sockfd, level, optname, results, &lv));
> +            if (ret < 0) {
> +                unlock_user(results, optval_addr, 0);
> +                return ret;
> +            }
> +            /* swap host endianess to target endianess. */
> +            for (i = 0; i < (len / sizeof(uint32_t)); i++) {
> +                results[i] = tswap32(results[i]);
> +            }
> +            if (put_user_u32(lv, optlen)) {
> +                return -TARGET_EFAULT;
> +            }
> +            unlock_user(results, optval_addr, 0);
> +            break;
> +        }
> +#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0) */
> +        default:
> +            goto unimplemented;
> +        }
> +#endif /* SOL_NETLINK */

Here at the end of the 'case SOL_NETLINK' we will just
fall straight through into 'default:'. Missing 'break' ?

>      default:
>      unimplemented:
>          gemu_log("getsockopt level=%d optname=%d not yet supported\n",
> --
> 2.21.0

thanks
-- PMM