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
shooting itself somewhere.

Fixes: 248411b8cb89 ("net/tcp: Wire up l3index to TCP-AO")
Signed-off-by: Dmitry Safonov <dima@arista.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;
+
 		/* It's still possible to bind after adding keys or even
 		 * re-bind to a different dev (with CAP_NET_RAW).
 		 * So, no reason to return error here, rather try to be
-- 
2.43.0

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@arista.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.


> +
>  		/* It's still possible to bind after adding keys or even
>  		 * re-bind to a different dev (with CAP_NET_RAW).
>  		 * So, no reason to return error here, rather try to be

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@arista.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