netdev - [PATCH net 3/3] tls: reset crypto_info when do_tls_setsockopt

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Date:   Tue, 16 Jan 2018 16:04:28 +0100
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     netdev@...r.kernel.org
Cc:     Sabrina Dubroca <sd@...asysnail.net>,
        Boris Pismenny <borisp@...lanox.com>,
        Ilya Lesokhin <ilyal@...lanox.com>,
        Aviad Yehezkel <aviadye@...lanox.com>,
        Dave Watson <davejwatson@...com>
Subject: [PATCH net 3/3] tls: reset crypto_info when do_tls_setsockopt_tx fails

The current code copies directly from userspace to ctx->crypto_send, but
doesn't always reinitialize it to 0 on failure. This causes any
subsequent attempt to use this setsockopt to fail because of the
TLS_CRYPTO_INFO_READY check, eventhough crypto_info is not actually
ready.

This should result in a correctly set up socket after the 3rd call, but
currently it does not:

    size_t s = sizeof(struct tls12_crypto_info_aes_gcm_128);
    struct tls12_crypto_info_aes_gcm_128 crypto_good = {
        .info.version = TLS_1_2_VERSION,
        .info.cipher_type = TLS_CIPHER_AES_GCM_128,
    };

    struct tls12_crypto_info_aes_gcm_128 crypto_bad_type = crypto_good;
    crypto_bad_type.info.cipher_type = 42;

    setsockopt(sock, SOL_TLS, TLS_TX, &crypto_bad_type, s);
    setsockopt(sock, SOL_TLS, TLS_TX, &crypto_good, s - 1);
    setsockopt(sock, SOL_TLS, TLS_TX, &crypto_good, s);

Fixes: 3c4d7559159b ("tls: kernel TLS support")
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 net/tls/tls_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index cdaaa9b8e84d..34f6b19672a4 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -388,7 +388,7 @@ static int do_tls_setsockopt_tx(struct sock *sk, char __user *optval,
 	case TLS_CIPHER_AES_GCM_128: {
 		if (optlen != sizeof(struct tls12_crypto_info_aes_gcm_128)) {
 			rc = -EINVAL;
-			goto out;
+			goto err_crypto_info;
 		}
 		rc = copy_from_user(crypto_info + 1, optval + sizeof(*crypto_info),
 				    optlen - sizeof(*crypto_info));
@@ -400,7 +400,7 @@ static int do_tls_setsockopt_tx(struct sock *sk, char __user *optval,
 	}
 	default:
 		rc = -EINVAL;
-		goto out;
+		goto err_crypto_info;
 	}
 
 	/* currently SW is default, we will have ethtool in future */
-- 
2.15.1