netdev - Re: [net v2] net/tls: fix corrupted data in recvmsg

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Message-ID: <20201116162608.2c54953e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Mon, 16 Nov 2020 16:26:08 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Vadim Fedorenko <vfedorenko@...ek.ru>
Cc:     Boris Pismenny <borisp@...dia.com>,
        Aviad Yehezkel <aviadye@...dia.com>, netdev@...r.kernel.org
Subject: Re: [net v2] net/tls: fix corrupted data in recvmsg

On Sun, 15 Nov 2020 07:16:00 +0300 Vadim Fedorenko wrote:
> If tcp socket has more data than Encrypted Handshake Message then
> tls_sw_recvmsg will try to decrypt next record instead of returning
> full control message to userspace as mentioned in comment. The next
> message - usually Application Data - gets corrupted because it uses
> zero copy for decryption that's why the data is not stored in skb
> for next iteration. Revert check to not decrypt next record if
> current is not Application Data.
> 
> Fixes: 692d7b5d1f91 ("tls: Fix recvmsg() to be able to peek across multiple records")
> Signed-off-by: Vadim Fedorenko <vfedorenko@...ek.ru>
> ---
>  net/tls/tls_sw.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
> index 95ab5545..2fe9e2c 100644
> --- a/net/tls/tls_sw.c
> +++ b/net/tls/tls_sw.c
> @@ -1913,7 +1913,7 @@ int tls_sw_recvmsg(struct sock *sk,
>  			 * another message type
>  			 */
>  			msg->msg_flags |= MSG_EOR;
> -			if (ctx->control != TLS_RECORD_TYPE_DATA)
> +			if (control != TLS_RECORD_TYPE_DATA)

Sorry I wasn't clear enough, should this be:

	if (ctx->control != control)

? Otherwise if we get a control record first and then data record
the code will collapse them, which isn't correct, right?

>  				goto recv_end;
>  		} else {
>  			break;