[PATCH v16 03/10] tls: reject rekey attempts on an existing HW-offloaded connection

[Rishikesh Jethwani <rjethwani@purestorage.com>]

On a TLS 1.3 rekey, do_tls_setsockopt_conf() must not dispatch to
tls_set_device_offload{,_rx}(): reject the rekey with -EOPNOTSUPP for a
HW-offloaded connection (HW KeyUpdate is not supported yet, and we must
not fall back to software mid-connection), and for a SW-offloaded one
re-init the software crypto state via tls_set_sw_offload() directly.

Prep for the following patch ("tls: add TLS 1.3 hardware offload
support"), which drops the TLS_1_2_VERSION guards in those helpers.
Those guards currently also reject a (TLS 1.3) rekey; once gone, a rekey
reaching tls_set_device_offload_rx(),which has no other early guard,
would set up a brand-new device offload instead of a key update.

Signed-off-by: Rishikesh Jethwani <rjethwani@purestorage.com>
---
 net/tls/tls_main.c | 85 +++++++++++++++++++++++++++-------------------
 1 file changed, 50 insertions(+), 35 deletions(-)

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index fbb274287aa5..a62e94508c8b 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -710,49 +710,64 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 	}
 
 	if (tx) {
-		rc = tls_set_device_offload(sk);
-		conf = TLS_HW;
-		if (!rc) {
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXDEVICE);
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXDEVICE);
-		} else {
-			rc = tls_set_sw_offload(sk, 1,
-						update ? crypto_info : NULL);
-			if (rc)
-				goto err_crypto_info;
-
-			if (update) {
-				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXREKEYOK);
-			} else {
-				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXSW);
-				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXSW);
+		if (update && ctx->tx_conf == TLS_HW) {
+			rc = -EOPNOTSUPP;
+			goto err_crypto_info;
+		}
+
+		if (!update) {
+			rc = tls_set_device_offload(sk);
+			conf = TLS_HW;
+			if (!rc) {
+				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXDEVICE);
+				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXDEVICE);
+				goto out;
 			}
-			conf = TLS_SW;
 		}
-	} else {
-		rc = tls_set_device_offload_rx(sk, ctx);
-		conf = TLS_HW;
-		if (!rc) {
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXDEVICE);
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXDEVICE);
+
+		rc = tls_set_sw_offload(sk, 1, update ? crypto_info : NULL);
+		if (rc)
+			goto err_crypto_info;
+
+		if (update) {
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXREKEYOK);
 		} else {
-			rc = tls_set_sw_offload(sk, 0,
-						update ? crypto_info : NULL);
-			if (rc)
-				goto err_crypto_info;
-
-			if (update) {
-				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXREKEYOK);
-			} else {
-				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXSW);
-				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXSW);
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXSW);
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXSW);
+		}
+		conf = TLS_SW;
+	} else {
+		if (update && ctx->rx_conf == TLS_HW) {
+			rc = -EOPNOTSUPP;
+			goto err_crypto_info;
+		}
+
+		if (!update) {
+			rc = tls_set_device_offload_rx(sk, ctx);
+			conf = TLS_HW;
+			if (!rc) {
+				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXDEVICE);
+				TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXDEVICE);
+				tls_sw_strparser_arm(sk, ctx);
+				goto out;
 			}
-			conf = TLS_SW;
 		}
-		if (!update)
+
+		rc = tls_set_sw_offload(sk, 0, update ? crypto_info : NULL);
+		if (rc)
+			goto err_crypto_info;
+
+		if (update) {
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXREKEYOK);
+		} else {
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXSW);
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXSW);
 			tls_sw_strparser_arm(sk, ctx);
+		}
+		conf = TLS_SW;
 	}
 
+out:
 	if (tx)
 		ctx->tx_conf = conf;
 	else
-- 
2.25.1