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Message-ID: <173d3b06-57ed-4e2e-9034-91b99f41512b@linux.dev>
Date: Fri, 23 Aug 2024 11:48:44 -0700
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Eric Dumazet <edumazet@...gle.com>, Feng zhou <zhoufeng.zf@...edance.com>
Cc: 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
Subject: Re: [PATCH bpf-next v2] bpf: Fix bpf_get/setsockopt to tos not take
effect when TCP over IPv4 via INET6 API
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.
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
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