linux-kernel - Re: [PATCH v3 5/7] net/tcp: Don't add key with non-matching VRF on connected sockets

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Date:   Wed, 29 Nov 2023 15:42:02 +0000
From:   Dmitry Safonov <dima@...sta.com>
To:     David Ahern <dsahern@...nel.org>
Cc:     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,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v3 5/7] net/tcp: Don't add key with non-matching VRF on
 connected sockets

Hi David,

On 11/29/23 01:34, David Ahern wrote:
> On 11/28/23 1:57 PM, Dmitry Safonov wrote:
>> If the connection was established, don't allow adding TCP-AO keys that
>> don't match the peer. Currently, there are checks for ip-address
>> matching, but L3 index check is missing. Add it to restrict userspace
> 
> you say L3 index check is missing - add it. yet ...
> 
>> shooting itself somewhere.
>>
>> Fixes: 248411b8cb89 ("net/tcp: Wire up l3index to TCP-AO")
>> Signed-off-by: Dmitry Safonov <dima@...sta.com>
>> ---
>>  net/ipv4/tcp_ao.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
>> index bf41be6d4721..2d000e275ce7 100644
>> --- a/net/ipv4/tcp_ao.c
>> +++ b/net/ipv4/tcp_ao.c
>> @@ -1608,6 +1608,9 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,
>>  		if (!dev || !l3index)
>>  			return -EINVAL;
>>  
>> +		if (!((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)))
>> +			return -EINVAL;
> 
> ... this is checking socket state.

Right you are, it should have been under check for
: if (bound_dev_if != cmd.ifindex)

Currently it's warning for all sockets (which can be re-bound), but for
sockets in the connected state it doesn't make sense as the key lookup
is not expecting non peer-matching key post connect()/accept().

In this patch version the check will restrict adding a key on a
connected socket with VRF regardless if it's matching the bound VRF.
Will fix!

Thanks for spotting this,
             Dmitry