RE: [PATCH] tls: Add support for encryption using async offload accelerator

[Vakul Garg]

Forgot to add 'v2' in subject line.
I will be resending.

-Original Message-
From: Vakul Garg 
Sent: Wednesday, January 31, 2018 9:29 PM
To: linux-cry...@vger.kernel.org
Cc: il...@mellanox.com; avia...@mellanox.com; davejwat...@fb.com; 
da...@davemloft.net; netdev@vger.kernel.org; Vakul Garg 
Subject: [PATCH] tls: Add support for encryption using async offload accelerator

Async crypto accelerators (e.g. drivers/crypto/caam) support offloading GCM 
operation. If they are enabled, crypto_aead_encrypt() return error code 
-EINPROGRESS. In this case tls_do_encryption() needs to wait on a completion 
till the time the response for crypto offload request is received.

Signed-off-by: Vakul Garg 
---
v1-v2:
 - Used crypto_wait_req() to wait for async operation completion
 - Passed CRYPTO_TFM_REQ_MAY_BACKLOG to crypto_aead_encrypt

 include/net/tls.h | 2 ++
 net/tls/tls_sw.c  | 8 +++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/net/tls.h b/include/net/tls.h index 
936cfc5cab7d..8a8e1256caee 100644
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -36,6 +36,7 @@
 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -57,6 +58,7 @@
 
 struct tls_sw_context {
struct crypto_aead *aead_send;
+   struct crypto_wait async_wait;
 
/* Sending context */
char aad_space[TLS_AAD_SPACE_SIZE];
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index 
73d19210dd49..31a9f0ef8af6 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -214,7 +214,11 @@ static int tls_do_encryption(struct tls_context *tls_ctx,
aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
aead_request_set_crypt(aead_req, ctx->sg_aead_in, ctx->sg_aead_out,
   data_len, tls_ctx->iv);
-   rc = crypto_aead_encrypt(aead_req);
+
+   aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+ crypto_req_done, >async_wait);
+
+   rc = crypto_wait_req(crypto_aead_encrypt(aead_req), >async_wait);
 
ctx->sg_encrypted_data[0].offset -= tls_ctx->prepend_size;
ctx->sg_encrypted_data[0].length += tls_ctx->prepend_size; @@ -663,6 
+667,8 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx)
goto out;
}
 
+   crypto_init_wait(_ctx->async_wait);
+
ctx->priv_ctx = (struct tls_offload_context *)sw_ctx;
 
crypto_info = >crypto_send;
--
2.13.6

Re: [PATCH] tls: Add support for encryption using async offload accelerator

[Gilad Ben-Yossef]

On Wed, Jan 31, 2018 at 8:10 AM, Gilad Ben-Yossef  wrote:
> Hi Vakul,
>
> On Wed, Jan 31, 2018 at 12:36 PM, Vakul Garg  wrote:
>> Async crypto accelerators (e.g. drivers/crypto/caam) support offloading
>> GCM operation. If they are enabled, crypto_aead_encrypt() return error
>> code -EINPROGRESS. In this case tls_do_encryption() needs to wait on a
>> completion till the time the response for crypto offload request is
>> received.
>>
>
> Thank you for this patch. I think it is actually a bug fix and should
> probably go into stable

On second though in stable we should probably just disable async tfm
allocations.
It's simpler. But this approach is still good for -next


Gilad


-- 
Gilad Ben-Yossef
Chief Coffee Drinker

"If you take a class in large-scale robotics, can you end up in a
situation where the homework eats your dog?"
 -- Jean-Baptiste Queru

Re: [PATCH] tls: Add support for encryption using async offload accelerator

[Gilad Ben-Yossef]

Hi Vakul,

On Wed, Jan 31, 2018 at 12:36 PM, Vakul Garg  wrote:
> Async crypto accelerators (e.g. drivers/crypto/caam) support offloading
> GCM operation. If they are enabled, crypto_aead_encrypt() return error
> code -EINPROGRESS. In this case tls_do_encryption() needs to wait on a
> completion till the time the response for crypto offload request is
> received.
>

Thank you for this patch. I think it is actually a bug fix and should
probably go into stable
since I believe current code is broken on machines where any async GCM
transformation
is registered with a high enough priority as it will try to call a
NULL callback.

But, please use the new crypto_wait_req() and friends to implement the waiting.
Take a look at the code example in
Documentation/crypto/api-samples.rst to see how.

Also, maybe add an explanation why  CRYPTO_TFM_REQ_MAY_BACKLOG
flag should not be used here, if this was on purpose?

I mean I'm not sure using backlog here is a good idea but probably
should explain why
not.

Thanks!
Gilad


> Signed-off-by: Vakul Garg 
> ---
>  net/tls/tls_sw.c | 22 ++
>  1 file changed, 22 insertions(+)
>
> diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
> index 73d19210dd49..390e6dc7b135 100644
> --- a/net/tls/tls_sw.c
> +++ b/net/tls/tls_sw.c
> @@ -39,6 +39,11 @@
>
>  #include 
>
> +struct crypto_completion {
> +   struct completion comp;
> +   int result;
> +};
> +
>  static void trim_sg(struct sock *sk, struct scatterlist *sg,
> int *sg_num_elem, unsigned int *sg_size, int target_size)
>  {
> @@ -194,6 +199,14 @@ static void tls_free_both_sg(struct sock *sk)
> >sg_plaintext_size);
>  }
>
> +static void crypto_complete(struct crypto_async_request *req, int err)
> +{
> +   struct crypto_completion *x = req->data;
> +
> +   x->result = err;
> +   complete(>comp);
> +}
> +
>  static int tls_do_encryption(struct tls_context *tls_ctx,
>  struct tls_sw_context *ctx, size_t data_len,
>  gfp_t flags)
> @@ -202,6 +215,7 @@ static int tls_do_encryption(struct tls_context *tls_ctx,
> crypto_aead_reqsize(ctx->aead_send);
> struct aead_request *aead_req;
> int rc;
> +   struct crypto_completion crypto_done;
>
> aead_req = kzalloc(req_size, flags);
> if (!aead_req)
> @@ -214,7 +228,15 @@ static int tls_do_encryption(struct tls_context *tls_ctx,
> aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
> aead_request_set_crypt(aead_req, ctx->sg_aead_in, ctx->sg_aead_out,
>data_len, tls_ctx->iv);
> +   aead_request_set_callback(aead_req, 0, crypto_complete, _done);
> +
> +   init_completion(_done.comp);
> +
> rc = crypto_aead_encrypt(aead_req);
> +   if (rc == -EINPROGRESS) {
> +   wait_for_completion(_done.comp);
> +   rc = crypto_done.result;
> +   }
>
> ctx->sg_encrypted_data[0].offset -= tls_ctx->prepend_size;
> ctx->sg_encrypted_data[0].length += tls_ctx->prepend_size;
> --
> 2.13.6
>



-- 
Gilad Ben-Yossef
Chief Coffee Drinker

"If you take a class in large-scale robotics, can you end up in a
situation where the homework eats your dog?"
 -- Jean-Baptiste Queru