[PATCH net-next] net/tls: Disable async decrytion for tls1.3

[PATCH net-next] net/tls: Disable async decrytion for tls1.3

[Vakul Garg]

Function tls_sw_recvmsg() dequeues multiple records from stream parser
and decrypts them. In case the decryption is done by async accelerator,
the records may get submitted for decryption while the previous ones may
not have been decryted yet. For tls1.3, the record type is known only
after decryption. Therefore, for tls1.3, tls_sw_recvmsg() may submit
records for decryption even if it gets 'handshake' records after 'data'
records. These intermediate 'handshake' records may do a key updation.
By the time new keys are given to ktls by userspace, it is possible that
ktls has already submitted some records i(which are encrypted with new
keys) for decryption using old keys. This would lead to decrypt failure.
Therefore, async decryption of records should be disabled for tls1.3.

Fixes: 130b392c6cd6b ("net: tls: Add tls 1.3 support")
Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
---
 net/tls/tls_sw.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 8051a9164139..fe8c287cbaa1 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2215,8 +2215,12 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
 
 	if (sw_ctx_rx) {
 		tfm = crypto_aead_tfm(sw_ctx_rx->aead_recv);
-		sw_ctx_rx->async_capable =
-			tfm->__crt_alg->cra_flags & CRYPTO_ALG_ASYNC;
+
+		if (crypto_info->version == TLS_1_3_VERSION)
+			sw_ctx_rx->async_capable = false;
+		else
+			sw_ctx_rx->async_capable =
+				tfm->__crt_alg->cra_flags & CRYPTO_ALG_ASYNC;
 
 		/* Set up strparser */
 		memset(&cb, 0, sizeof(cb));
-- 
2.13.6

Re: [PATCH net-next] net/tls: Disable async decrytion for tls1.3

[David Miller]

From: Vakul Garg <vakul.garg@nxp.com>
Date: Sat, 9 Feb 2019 07:53:28 +0000

> Function tls_sw_recvmsg() dequeues multiple records from stream parser
> and decrypts them. In case the decryption is done by async accelerator,
> the records may get submitted for decryption while the previous ones may
> not have been decryted yet. For tls1.3, the record type is known only
> after decryption. Therefore, for tls1.3, tls_sw_recvmsg() may submit
> records for decryption even if it gets 'handshake' records after 'data'
> records. These intermediate 'handshake' records may do a key updation.
> By the time new keys are given to ktls by userspace, it is possible that
> ktls has already submitted some records i(which are encrypted with new
> keys) for decryption using old keys. This would lead to decrypt failure.
> Therefore, async decryption of records should be disabled for tls1.3.
> 
> Fixes: 130b392c6cd6b ("net: tls: Add tls 1.3 support")
> Signed-off-by: Vakul Garg <vakul.garg@nxp.com>

Applied, thank you.