netdev - [PATCH net] net/tls: avoid spurious decryption error with HW resync

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Date:   Fri, 10 Jan 2020 04:36:55 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        borisp@...lanox.com, aviadye@...lanox.com,
        john.fastabend@...il.com, daniel@...earbox.net,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        David Beckett <david.beckett@...ronome.com>,
        Simon Horman <simon.horman@...ronome.com>
Subject: [PATCH net] net/tls: avoid spurious decryption error with HW resync

When device loses sync mid way through a record - kernel
has to re-encrypt the part of the record which the device
already decrypted to be able to decrypt and authenticate
the record in its entirety.

The re-encryption piggy backs on the decryption routine,
but obviously because the partially decrypted record can't
be authenticated crypto API returns an error which is then
ignored by tls_device_reencrypt().

Commit 5c5ec6685806 ("net/tls: add TlsDecryptError stat")
added a statistic to count decryption errors, this statistic
can't be incremented when we see the expected re-encryption
error. Move the inc to the caller.

Reported-and-tested-by: David Beckett <david.beckett@...ronome.com>
Fixes: 5c5ec6685806 ("net/tls: add TlsDecryptError stat")
Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Simon Horman <simon.horman@...ronome.com>
---
 net/tls/tls_sw.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index bb229dc0fa81..5c7c00429f8e 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -256,8 +256,6 @@ static int tls_do_decryption(struct sock *sk,
 			return ret;
 
 		ret = crypto_wait_req(ret, &ctx->async_wait);
-	} else if (ret == -EBADMSG) {
-		TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSDECRYPTERROR);
 	}
 
 	if (async)
@@ -1515,7 +1513,9 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
 				if (err == -EINPROGRESS)
 					tls_advance_record_sn(sk, prot,
 							      &tls_ctx->rx);
-
+				else if (err == -EBADMSG)
+					TLS_INC_STATS(sock_net(sk),
+						      LINUX_MIB_TLSDECRYPTERROR);
 				return err;
 			}
 		} else {
-- 
2.23.0