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

[Laurent Vivier <laurent@vivier.eu>]

Le 12/11/2019 à 11:11, Peter Maydell a écrit :
> 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' ?

Yes, missing 'break'.

I'm going to send a patch to fix that.

Thanks,
Laurent