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

[Jakub Kicinski]

On Sat, 14 Nov 2020 07:09:42 +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. Disable zero copy for this case.
> 
> Fixes: 692d7b5d1f91 ("tls: Fix recvmsg() to be able to peek across multiple 
> records")
> Signed-off-by: Vadim Fedorenko <vfedore...@novek.ru>

Do you have some BPF in the mix?

I don't see how we would try to go past a non-data record otherwise, 
since the loop ends like this:

                if (tls_sw_advance_skb(sk, skb, chunk)) {
                        /* Return full control message to
                         * userspace before trying to parse
                         * another message type
                         */
                        msg->msg_flags |= MSG_EOR;
                        if (ctx->control != TLS_RECORD_TYPE_DATA)
                                goto recv_end;
                } else {
                        break;
                }