netdev - Re: [PATCH net 4/4] tls: Fix tls

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Message-ID: <e35a912b-7f09-92f9-8f3c-bbf0def3eae0@mellanox.com>
Date:   Wed, 27 Feb 2019 15:23:44 +0000
From:   Boris Pismenny <borisp@...lanox.com>
To:     Vakul Garg <vakul.garg@....com>, Dave Watson <davejwatson@...com>
CC:     Aviad Yehezkel <aviadye@...lanox.com>,
        "john.fastabend@...il.com" <john.fastabend@...il.com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Eran Ben Elisha <eranbe@...lanox.com>
Subject: Re: [PATCH net 4/4] tls: Fix tls_device receive



On 2/27/2019 5:08 AM, Vakul Garg wrote:
> 
> 
>> -----Original Message-----
>> From: Dave Watson <davejwatson@...com>
>> Sent: Wednesday, February 27, 2019 2:05 AM
>> To: Boris Pismenny <borisp@...lanox.com>
>> Cc: aviadye@...lanox.com; john.fastabend@...il.com;
>> daniel@...earbox.net; Vakul Garg <vakul.garg@....com>;
>> netdev@...r.kernel.org; eranbe@...lanox.com
>> Subject: Re: [PATCH net 4/4] tls: Fix tls_device receive
>>
>> On 02/26/19 02:12 PM, Boris Pismenny wrote:
>>> Currently, the receive function fails to handle records already
>>> decrypted by the device due to the commit mentioned below.
>>>
>>> This commit advances the TLS record sequence number and prepares the
>>> context to handle the next record.
>>>
>>> Fixes: fedf201e1296 ("net: tls: Refactor control message handling on
>>> recv")
>>> Signed-off-by: Boris Pismenny <borisp@...lanox.com>
>>> Reviewed-by: Eran Ben Elisha <eranbe@...lanox.com>
>>> ---
>>>   net/tls/tls_sw.c | 15 +++++++--------
>>>   1 file changed, 7 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index
>>> f515cd7e984e..85da10182d8d 100644
>>> --- a/net/tls/tls_sw.c
>>> +++ b/net/tls/tls_sw.c
>>> @@ -1481,18 +1481,17 @@ static int decrypt_skb_update(struct sock *sk,
>>> struct sk_buff *skb,
>>>
>>>   			return err;
>>>   		}
>>> -
>>> -		rxm->full_len -= padding_length(ctx, tls_ctx, skb);
>>> -
>>> -		rxm->offset += prot->prepend_size;
>>> -		rxm->full_len -= prot->overhead_size;
>>> -		tls_advance_record_sn(sk, &tls_ctx->rx, version);
>>> -		ctx->decrypted = true;
>>> -		ctx->saved_data_ready(sk);
>>>   	} else {
>>>   		*zc = false;
>>>   	}
>>>
>>> +	rxm->full_len -= padding_length(ctx, tls_ctx, skb);
>>> +	rxm->offset += prot->prepend_size;
>>> +	rxm->full_len -= prot->overhead_size;
>>> +	tls_advance_record_sn(sk, &tls_ctx->rx, version);
>>> +	ctx->decrypted = true;
>>> +	ctx->saved_data_ready(sk);
>>> +
>>>   	return err;
>>>   }
>>
>> This breaks the tls.control_msg test:
>>
>>    [ RUN      ] tls.control_msg
>>    tls.c:764:tls.control_msg:Expected memcmp(buf, test_str, send_len)
>> (18446744073709551614) == 0 (0)
>>    tls.c:777:tls.control_msg:Expected memcmp(buf, test_str, send_len)
>> (18446744073709551614) == 0 (0)
>>    tls.control_msg: Test failed at step #8
>>
>> So either control message handling needs to only call decrypt_skb_update
>> once, or we need a new flag or something to handle the device case
> 
> I prefer to remove variable 'decrypted' in context.
> This is no longer required as we already have an rx_list in context for storing decrypted records.
> So for any record which we decrypted but did not return to user space
> (e.g. for the case when user used recv() and it lead to decryption of non-data record), we should
> it in rx_list.
>   

IMO this is inappropriate here, because packets decrypted by tls_device 
are ready to be received, and there is no reason to bounce them through 
the rx_list.