linux-kernel - Re: Re: [PATCH bpf-next v2] bpf: Fix bpf_get/setsockopt to tos not take effect when TCP over IPv4 via INET6 API

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Message-ID: <324669ea-e684-4a84-ab70-33f8c857db0a@bytedance.com>
Date: Sat, 14 Sep 2024 10:19:56 +0800
From: Feng Zhou <zhoufeng.zf@...edance.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: Martin KaFai Lau <martin.lau@...ux.dev>, davem@...emloft.net,
 kuba@...nel.org, pabeni@...hat.com, ast@...nel.org, daniel@...earbox.net,
 andrii@...nel.org, eddyz87@...il.com, song@...nel.org,
 yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org,
 sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org, dsahern@...nel.org,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
 yangzhenze@...edance.com, wangdongdong.6@...edance.com,
 YiFei Zhu <zhuyifei@...gle.com>
Subject: Re: Re: [PATCH bpf-next v2] bpf: Fix bpf_get/setsockopt to tos not
 take effect when TCP over IPv4 via INET6 API

在 2024/9/13 22:44, Eric Dumazet 写道:
> On Tue, Aug 27, 2024 at 10:08 AM Feng Zhou <zhoufeng.zf@...edance.com> wrote:
>>
>> 在 2024/8/24 02:53, Eric Dumazet 写道:
>>> On Fri, Aug 23, 2024 at 8:49 PM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>>>>
>>>> On 8/23/24 6:35 AM, Eric Dumazet wrote:
>>>>> On Fri, Aug 23, 2024 at 10:53 AM Feng zhou <zhoufeng.zf@...edance.com> wrote:
>>>>>>
>>>>>> From: Feng Zhou <zhoufeng.zf@...edance.com>
>>>>>>
>>>>>> when TCP over IPv4 via INET6 API, bpf_get/setsockopt with ipv4 will
>>>>>> fail, because sk->sk_family is AF_INET6. With ipv6 will success, not
>>>>>> take effect, because inet_csk(sk)->icsk_af_ops is ipv6_mapped and
>>>>>> use ip_queue_xmit, inet_sk(sk)->tos.
>>>>>>
>>>>>> So bpf_get/setsockopt needs add the judgment of this case. Just check
>>>>>> "inet_csk(sk)->icsk_af_ops == &ipv6_mapped".
>>>>>>
>>>>>> | Reported-by: kernel test robot <lkp@...el.com>
>>>>>> | Closes: https://lore.kernel.org/oe-kbuild-all/202408152034.lw9Ilsj6-lkp@intel.com/
>>>>>> Signed-off-by: Feng Zhou <zhoufeng.zf@...edance.com>
>>>>>> ---
>>>>>> Changelog:
>>>>>> v1->v2: Addressed comments from kernel test robot
>>>>>> - Fix compilation error
>>>>>> Details in here:
>>>>>> https://lore.kernel.org/bpf/202408152058.YXAnhLgZ-lkp@intel.com/T/
>>>>>>
>>>>>>     include/net/tcp.h   | 2 ++
>>>>>>     net/core/filter.c   | 6 +++++-
>>>>>>     net/ipv6/tcp_ipv6.c | 6 ++++++
>>>>>>     3 files changed, 13 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/include/net/tcp.h b/include/net/tcp.h
>>>>>> index 2aac11e7e1cc..ea673f88c900 100644
>>>>>> --- a/include/net/tcp.h
>>>>>> +++ b/include/net/tcp.h
>>>>>> @@ -493,6 +493,8 @@ struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
>>>>>>                                                struct tcp_options_received *tcp_opt,
>>>>>>                                                int mss, u32 tsoff);
>>>>>>
>>>>>> +bool is_tcp_sock_ipv6_mapped(struct sock *sk);
>>>>>> +
>>>>>>     #if IS_ENABLED(CONFIG_BPF)
>>>>>>     struct bpf_tcp_req_attrs {
>>>>>>            u32 rcv_tsval;
>>>>>> diff --git a/net/core/filter.c b/net/core/filter.c
>>>>>> index ecf2ddf633bf..02a825e35c4d 100644
>>>>>> --- a/net/core/filter.c
>>>>>> +++ b/net/core/filter.c
>>>>>> @@ -5399,7 +5399,11 @@ static int sol_ip_sockopt(struct sock *sk, int optname,
>>>>>>                              char *optval, int *optlen,
>>>>>>                              bool getopt)
>>>>>>     {
>>>>>> -       if (sk->sk_family != AF_INET)
>>>>>> +       if (sk->sk_family != AF_INET
>>>>>> +#if IS_BUILTIN(CONFIG_IPV6)
>>>>>> +           && !is_tcp_sock_ipv6_mapped(sk)
>>>>>> +#endif
>>>>>> +           )
>>>>>>                    return -EINVAL;
>>>>>
>>>>> This does not look right to me.
>>>>>
>>>>> I would remove the test completely.
>>>>>
>>>>> SOL_IP socket options are available on AF_INET6 sockets just fine.
>>>>
>>>> Good point on the SOL_IP options.
>>>>
>>>> The sk could be neither AF_INET nor AF_INET6. e.g. the bpf_get/setsockopt
>>>> calling from the bpf_lsm's socket_post_create). so the AF_INET test is still needed.
>>>>
>>>
>>> OK, then I suggest using sk_is_inet() helper.
>>>
>>>> Adding "&& sk->sk_family != AF_INET6" should do. From ipv6_setsockopt, I think
>>>> it also needs to consider the "sk->sk_type != SOCK_RAW".
>>>>
>>>> Please add a test in the next re-spin.
>>>>
>>>> pw-bot: cr
>>
>> Thanks for your suggestion, I will add it in the next version.
> 
> Gentle ping.
> 
> Have you sent the new version ?

Sorry, there have been a lot of delays in work recently. V3 will be sent 
in two days. Thanks.