netdev - Re: [PATCH 3/7] net/tcp: Limit TCP_AO

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Date: Tue, 21 Nov 2023 17:50:14 +0000
From: Dmitry Safonov <dima@...sta.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: David Ahern <dsahern@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Jakub Kicinski <kuba@...nel.org>, "David S. Miller" <davem@...emloft.net>,
 linux-kernel@...r.kernel.org, Dmitry Safonov <0x7f454c46@...il.com>,
 Francesco Ruggeri <fruggeri05@...il.com>,
 Salam Noureddine <noureddine@...sta.com>, Simon Horman <horms@...nel.org>,
 netdev@...r.kernel.org
Subject: Re: [PATCH 3/7] net/tcp: Limit TCP_AO_REPAIR to non-listen sockets

On 11/21/23 08:21, Eric Dumazet wrote:
> On Tue, Nov 21, 2023 at 3:01 AM Dmitry Safonov <dima@...sta.com> wrote:
>>
>> Listen socket is not an established TCP connection, so
>> setsockopt(TCP_AO_REPAIR) doesn't have any impact.
>>
>> Restrict this uAPI for listen sockets.
>>
>> Fixes: faadfaba5e01 ("net/tcp: Add TCP_AO_REPAIR")
>> Signed-off-by: Dmitry Safonov <dima@...sta.com>
>> ---
>>  net/ipv4/tcp.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
>> index 53bcc17c91e4..2836515ab3d7 100644
>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -3594,6 +3594,10 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
>>                 break;
>>
>>         case TCP_AO_REPAIR:
>> +               if (sk->sk_state == TCP_LISTEN) {
>> +                       err = -ENOSTR;
> 
> ENOSTR is not used a single time in linux.
> 
> I suggest you use tcp_can_repair_sock() helper (and return -EPERM as
> other TCP_REPAIR options)

Sounds good to me. Unsure why I didn't use tcp_can_repair_sock() in the
first place. Will do in v2.

> 
>> +                       break;
>> +               }
>>                 err = tcp_ao_set_repair(sk, optval, optlen);
>>                 break;
>>  #ifdef CONFIG_TCP_AO
>> @@ -4293,6 +4297,8 @@ int do_tcp_getsockopt(struct sock *sk, int level,
>>         }
>>  #endif
>>         case TCP_AO_REPAIR:
>> +               if (sk->sk_state == TCP_LISTEN)
>> +                       return -ENOSTR;
>>                 return tcp_ao_get_repair(sk, optval, optlen);
>>         case TCP_AO_GET_KEYS:
>>         case TCP_AO_INFO: {
>> --
>> 2.42.0
>>

Thanks,
             Dmitry