netdev - Re: [PATCH RFC v2 net-next] net/tls: Implement getsockopt SOL_TLS TLS

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Date:   Mon, 31 Aug 2020 02:48:25 +0900
From:   Yutaro Hayakawa <yhayakawa3720@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Michio Honda <michio.honda@...ac.uk>
Subject: Re: [PATCH RFC v2 net-next] net/tls: Implement getsockopt SOL_TLS TLS_RX

Apology. Kernel Test Robot just pointed out that the v2 patch has a
compilation error. My local compilation tests have passed because I
didn't enable the kTLS kernel option. Let me resubmit the fixed
version soon.

Yutaro

2020年8月30日(日) 23:02 Yutaro Hayakawa <yhayakawa3720@...il.com>:
>
> From: Yutaro Hayakawa <yhayakawa3720@...il.com>
>
> Implement the getsockopt SOL_TLS TLS_RX which is currently missing. The
> primary usecase is to use it in conjunction with TCP_REPAIR to
> checkpoint/restore the TLS record layer state.
>
> TLS connection state usually exists on the user space library. So
> basically we can easily extract it from there, but when the TLS
> connections are delegated to the kTLS, it is not the case. We need to
> have a way to extract the TLS state from the kernel for both of TX and
> RX side.
>
> The new TLS_RX getsockopt copies the crypto_info to user in the same
> way as TLS_TX does.
>
> We have described use cases in our research work in Netdev 0x14
> Transport Workshop [1].
>
> Also, there is an TLS implementation called tlse [2] which supports
> TLS connection migration. They have support of kTLS and their code
> shows that they are expecting the future support of this option.
>
> [1] https://speakerdeck.com/yutarohayakawa/prism-proxies-without-the-pain
> [2] https://github.com/eduardsui/tlse
>
> Signed-off-by: Yutaro Hayakawa <yhayakawa3720@...il.com>
> ---
> Changes in v2:
> - Remove duplicated memcpy for each cipher suites
>
> Thanks for your reply. Reflected the comments.
>
>  net/tls/tls_main.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> index bbc52b0..0271441 100644
> --- a/net/tls/tls_main.c
> +++ b/net/tls/tls_main.c
> @@ -330,12 +330,13 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
>                 tls_ctx_free(sk, ctx);
>  }
>
> -static int do_tls_getsockopt_tx(struct sock *sk, char __user *optval,
> -                               int __user *optlen)
> +static int do_tls_getsockopt_conf(struct sock *sk, char __user *optval,
> +                                 int __user *optlen, int tx)
>  {
>         int rc = 0;
>         struct tls_context *ctx = tls_get_ctx(sk);
>         struct tls_crypto_info *crypto_info;
> +       struct tls_cipher_context *cctx;
>         int len;
>
>         if (get_user(len, optlen))
> @@ -352,7 +353,13 @@ static int do_tls_getsockopt_tx(struct sock *sk, char __user *optval,
>         }
>
>         /* get user crypto info */
> -       crypto_info = &ctx->crypto_send.info;
> +       if (tx) {
> +               crypto_info = &ctx->crypto_send.info;
> +               cctx = &ctx->tx;
> +       } else {
> +               crypto_info = &ctx->crypto_recv.info;
> +               cctx = &ctx->rx;
> +       }
>
>         if (!TLS_CRYPTO_INFO_READY(crypto_info)) {
>                 rc = -EBUSY;
> @@ -379,9 +386,9 @@ static int do_tls_getsockopt_tx(struct sock *sk, char __user *optval,
>                 }
>                 lock_sock(sk);
>                 memcpy(crypto_info_aes_gcm_128->iv,
> -                      ctx->tx.iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
> +                      cctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
>                        TLS_CIPHER_AES_GCM_128_IV_SIZE);
> -               memcpy(crypto_info_aes_gcm_128->rec_seq, ctx->tx.rec_seq,
> +               memcpy(crypto_info_aes_gcm_128->rec_seq, cctx->rec_seq,
>                        TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE);
>                 release_sock(sk);
>                 if (copy_to_user(optval,
> @@ -403,9 +410,9 @@ static int do_tls_getsockopt_tx(struct sock *sk, char __user *optval,
>                 }
>                 lock_sock(sk);
>                 memcpy(crypto_info_aes_gcm_256->iv,
> -                      ctx->tx.iv + TLS_CIPHER_AES_GCM_256_SALT_SIZE,
> +                      cctx->iv + TLS_CIPHER_AES_GCM_256_SALT_SIZE,
>                        TLS_CIPHER_AES_GCM_256_IV_SIZE);
> -               memcpy(crypto_info_aes_gcm_256->rec_seq, ctx->tx.rec_seq,
> +               memcpy(crypto_info_aes_gcm_256->rec_seq, cctx->rec_seq,
>                        TLS_CIPHER_AES_GCM_256_REC_SEQ_SIZE);
>                 release_sock(sk);
>                 if (copy_to_user(optval,
> @@ -429,7 +436,9 @@ static int do_tls_getsockopt(struct sock *sk, int optname,
>
>         switch (optname) {
>         case TLS_TX:
> -               rc = do_tls_getsockopt_tx(sk, optval, optlen);
> +       case TLS_RX:
> +               rc = do_tls_getsockopt_conf(sk, optval, optlen,
> +                                           optname == TLS_TX);
>                 break;
>         default:
>                 rc = -ENOPROTOOPT;
> --
> 1.8.3.1