Re: [PATCH v1 3/4] linux-user: add target to host netlink conversions

[Philippe Mathieu-Daudé]

On 17/2/23 17:35, Mathis Marion wrote:
> From: Mathis Marion <mathis.marion@silabs.com>
>
> Added conversions for:
> - IFLA_MTU
> - IFLA_TXQLEN
> - IFLA_AF_SPEC AF_INET6 IFLA_INET6_ADDR_GEN_MODE
> These relate to the libnl functions rtnl_link_set_mtu,
> rtnl_link_set_txqlen, and rtnl_link_inet6_set_addr_gen_mode.
>
> Signed-off-by: Mathis Marion <mathis.marion@silabs.com>
> ---
>   linux-user/fd-trans.c | 64 +++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 64 insertions(+)
>
> diff --git a/linux-user/fd-trans.c b/linux-user/fd-trans.c
> index 146aaaafaa..aa398098ec 100644
> --- a/linux-user/fd-trans.c
> +++ b/linux-user/fd-trans.c
> @@ -1284,6 +1284,49 @@ static inline abi_long host_to_target_nlmsg_route(struct 
> nlmsghdr *nlh,
>       return host_to_target_for_each_nlmsg(nlh, len, host_to_target_data_route);
>   }
>   
> +static abi_long target_to_host_for_each_nlattr(struct nlattr *nlattr,
> +                                               size_t len, void *context,

You always pass a NULL context... Do we really need it?

> +                                               abi_long 
> (*target_to_host_nlattr)
> +                                                        (struct nlattr *))
> +{
> +    unsigned short aligned_nla_len;
> +    abi_long ret;
> +
> +    while (len > sizeof(struct nlattr)) {
> +        if (tswap16(nlattr->nla_len) < sizeof(struct rtattr) ||
> +            tswap16(nlattr->nla_len) > len) {
> +            break;
> +        }
> +        nlattr->nla_len = tswap16(nlattr->nla_len);
> +        nlattr->nla_type = tswap16(nlattr->nla_type);
> +        ret = target_to_host_nlattr(nlattr);
> +        if (ret < 0) {

If this fail, guest's nlattr is now inconsistent. Is this OK?

> +            return ret;
> +        }
> +
> +        aligned_nla_len = NLA_ALIGN(nlattr->nla_len);
> +        if (aligned_nla_len >= len) {
> +            break;
> +        }
> +        len -= aligned_nla_len;
> +        nlattr = (struct nlattr *)(((char *)nlattr) + aligned_nla_len);
> +    }
> +    return 0;
> +}
> +
> +static abi_long target_to_host_data_inet6_nlattr(struct nlattr *nlattr)
> +{
> +    switch (nlattr->nla_type) {
> +    /* uint8_t */
> +    case QEMU_IFLA_INET6_ADDR_GEN_MODE:
> +        break;
> +    default:
> +        qemu_log_mask(LOG_UNIMP, "Unknown target AF_INET6 type: %d\n",
> +                      nlattr->nla_type);
> +    }
> +    return 0;
> +}
> +
>   static abi_long target_to_host_for_each_rtattr(struct rtattr *rtattr,
>                                                  size_t len,
>                                                  abi_long 
> (*target_to_host_rtattr)
> @@ -1314,16 +1357,37 @@ static abi_long target_to_host_for_each_rtattr(struct 
> rtattr *rtattr,
>       return 0;
>   }
>   
> +static abi_long target_to_host_data_spec_nlattr(struct nlattr *nlattr)
> +{
> +    switch (nlattr->nla_type) {
> +    case AF_INET6:
> +        return target_to_host_for_each_nlattr(NLA_DATA(nlattr), 
> nlattr->nla_len,
> +                                              NULL,
> +                                              
> target_to_host_data_inet6_nlattr);
> +    default:
> +        qemu_log_mask(LOG_UNIMP, "Unknown target AF_SPEC type: %d\n",
> +                      nlattr->nla_type);
> +        break;
> +    }
> +    return 0;
> +}
> +
>   static abi_long target_to_host_data_link_rtattr(struct rtattr *rtattr)
>   {
>       uint32_t *u32;
>   
>       switch (rtattr->rta_type) {
>       /* uint32_t */
> +    case QEMU_IFLA_MTU:
> +    case QEMU_IFLA_TXQLEN:
>       case QEMU_IFLA_EXT_MASK:
>           u32 = RTA_DATA(rtattr);
>           *u32 = tswap32(*u32);
>           break;
> +    case QEMU_IFLA_AF_SPEC:
> +        return target_to_host_for_each_nlattr(RTA_DATA(rtattr), 
> rtattr->rta_len,
> +                                              NULL,
> +                                              target_to_host_data_spec_nlattr);
>       default:
>           qemu_log_mask(LOG_UNIMP, "Unknown target QEMU_IFLA type: %d\n",
>                         rtattr->rta_type);