tls: rx: add sockopt for enabling optimistic decrypt with TLS 1.3

Since optimisitic decrypt may add extra load in case of retries
require socket owner to explicitly opt-in.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 90 insertions, 7 deletions

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 2ffede463e4a5c..1b3efc96db0bee 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -533,6 +533,37 @@ static int do_tls_getsockopt_tx_zc(struct sock *sk, char __user *optval,
 	return 0;
 }
 
+static int do_tls_getsockopt_no_pad(struct sock *sk, char __user *optval,
+				    int __user *optlen)
+{
+	struct tls_context *ctx = tls_get_ctx(sk);
+	unsigned int value;
+	int err, len;
+
+	if (ctx->prot_info.version != TLS_1_3_VERSION)
+		return -EINVAL;
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+	if (len < sizeof(value))
+		return -EINVAL;
+
+	lock_sock(sk);
+	err = -EINVAL;
+	if (ctx->rx_conf == TLS_SW || ctx->rx_conf == TLS_HW)
+		value = ctx->rx_no_pad;
+	release_sock(sk);
+	if (err)
+		return err;
+
+	if (put_user(sizeof(value), optlen))
+		return -EFAULT;
+	if (copy_to_user(optval, &value, sizeof(value)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static int do_tls_getsockopt(struct sock *sk, int optname,
 			     char __user *optval, int __user *optlen)
 {
@@ -547,6 +578,9 @@ static int do_tls_getsockopt(struct sock *sk, int optname,
 	case TLS_TX_ZEROCOPY_RO:
 		rc = do_tls_getsockopt_tx_zc(sk, optval, optlen);
 		break;
+	case TLS_RX_EXPECT_NO_PAD:
+		rc = do_tls_getsockopt_no_pad(sk, optval, optlen);
+		break;
 	default:
 		rc = -ENOPROTOOPT;
 		break;
@@ -718,6 +752,38 @@ static int do_tls_setsockopt_tx_zc(struct sock *sk, sockptr_t optval,
 	return 0;
 }
 
+static int do_tls_setsockopt_no_pad(struct sock *sk, sockptr_t optval,
+				    unsigned int optlen)
+{
+	struct tls_context *ctx = tls_get_ctx(sk);
+	u32 val;
+	int rc;
+
+	if (ctx->prot_info.version != TLS_1_3_VERSION ||
+	    sockptr_is_null(optval) || optlen < sizeof(val))
+		return -EINVAL;
+
+	rc = copy_from_sockptr(&val, optval, sizeof(val));
+	if (rc)
+		return -EFAULT;
+	if (val > 1)
+		return -EINVAL;
+	rc = check_zeroed_sockptr(optval, sizeof(val), optlen - sizeof(val));
+	if (rc < 1)
+		return rc == 0 ? -EINVAL : rc;
+
+	lock_sock(sk);
+	rc = -EINVAL;
+	if (ctx->rx_conf == TLS_SW || ctx->rx_conf == TLS_HW) {
+		ctx->rx_no_pad = val;
+		tls_update_rx_zc_capable(ctx);
+		rc = 0;
+	}
+	release_sock(sk);
+
+	return rc;
+}
+
 static int do_tls_setsockopt(struct sock *sk, int optname, sockptr_t optval,
 			     unsigned int optlen)
 {
@@ -736,6 +802,9 @@ static int do_tls_setsockopt(struct sock *sk, int optname, sockptr_t optval,
 		rc = do_tls_setsockopt_tx_zc(sk, optval, optlen);
 		release_sock(sk);
 		break;
+	case TLS_RX_EXPECT_NO_PAD:
+		rc = do_tls_setsockopt_no_pad(sk, optval, optlen);
+		break;
 	default:
 		rc = -ENOPROTOOPT;
 		break;
@@ -976,6 +1045,11 @@ static int tls_get_info(const struct sock *sk, struct sk_buff *skb)
 		if (err)
 			goto nla_failure;
 	}
+	if (ctx->rx_no_pad) {
+		err = nla_put_flag(skb, TLS_INFO_RX_NO_PAD);
+		if (err)
+			goto nla_failure;
+	}
 
 	rcu_read_unlock();
 	nla_nest_end(skb, start);
@@ -997,6 +1071,7 @@ static size_t tls_get_info_size(const struct sock *sk)
 		nla_total_size(sizeof(u16)) +	/* TLS_INFO_RXCONF */
 		nla_total_size(sizeof(u16)) +	/* TLS_INFO_TXCONF */
 		nla_total_size(0) +		/* TLS_INFO_ZC_RO_TX */
+		nla_total_size(0) +		/* TLS_INFO_RX_NO_PAD */
 		0;
 
 	return size;
diff --git a/net/tls/tls_proc.c b/net/tls/tls_proc.c
index feeceb0e4cb48d..0c200000cc4579 100644
--- a/net/tls/tls_proc.c
+++ b/net/tls/tls_proc.c
@@ -18,6 +18,7 @@ static const struct snmp_mib tls_mib_list[] = {
 	SNMP_MIB_ITEM("TlsRxDevice", LINUX_MIB_TLSRXDEVICE),
 	SNMP_MIB_ITEM("TlsDecryptError", LINUX_MIB_TLSDECRYPTERROR),
 	SNMP_MIB_ITEM("TlsRxDeviceResync", LINUX_MIB_TLSRXDEVICERESYNC),
+	SNMP_MIB_ITEM("TlsDecryptRetry", LINUX_MIN_TLSDECRYPTRETRY),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 2bac5768442922..7592b65199534b 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -1601,6 +1601,7 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
 	if (unlikely(darg->zc && prot->version == TLS_1_3_VERSION &&
 		     darg->tail != TLS_RECORD_TYPE_DATA)) {
 		darg->zc = false;
+		TLS_INC_STATS(sock_net(sk), LINUX_MIN_TLSDECRYPTRETRY);
 		return decrypt_skb_update(sk, skb, dest, darg);
 	}
 
@@ -1787,7 +1788,7 @@ int tls_sw_recvmsg(struct sock *sk,
 	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 
 	zc_capable = !bpf_strp_enabled && !is_kvec && !is_peek &&
-		     prot->version != TLS_1_3_VERSION;
+		ctx->zc_capable;
 	decrypted = 0;
 	while (len && (decrypted + copied < target || ctx->recv_pkt)) {
 		struct tls_decrypt_arg darg = {};
@@ -2269,6 +2270,14 @@ void tls_sw_strparser_arm(struct sock *sk, struct tls_context *tls_ctx)
 	strp_check_rcv(&rx_ctx->strp);
 }
 
+void tls_update_rx_zc_capable(struct tls_context *tls_ctx)
+{
+	struct tls_sw_context_rx *rx_ctx = tls_sw_ctx_rx(tls_ctx);
+
+	rx_ctx->zc_capable = tls_ctx->rx_no_pad ||
+		tls_ctx->prot_info.version != TLS_1_3_VERSION;
+}
+
 int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
@@ -2504,12 +2513,10 @@ 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);
 
-		if (crypto_info->version == TLS_1_3_VERSION)
-			sw_ctx_rx->async_capable = 0;
-		else
-			sw_ctx_rx->async_capable =
-				!!(tfm->__crt_alg->cra_flags &
-				   CRYPTO_ALG_ASYNC);
+		tls_update_rx_zc_capable(ctx);
+		sw_ctx_rx->async_capable =
+			crypto_info->version != TLS_1_3_VERSION &&
+			!!(tfm->__crt_alg->cra_flags & CRYPTO_ALG_ASYNC);
 
 		/* Set up strparser */
 		memset(&cb, 0, sizeof(cb));