net/tls: add statistics for installed sessions

Add SNMP stats for number of sockets with successfully
installed sessions.  Break them down to software and
hardware ones.  Note that if hardware offload fails
stack uses software implementation, and counts the
session appropriately.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/tls.rst

@@ -219,3 +219,17 @@ Statistics
 
 TLS implementation exposes the following per-namespace statistics
 (``/proc/net/tls_stat``):
+
+- ``TlsCurrTxSw``, ``TlsCurrRxSw`` -
+  number of TX and RX sessions currently installed where host handles
+  cryptography
+
+- ``TlsCurrTxDevice``, ``TlsCurrRxDevice`` -
+  number of TX and RX sessions currently installed where NIC handles
+  cryptography
+
+- ``TlsTxSw``, ``TlsRxSw`` -
+  number of TX and RX sessions opened with host cryptography
+
+- ``TlsTxDevice``, ``TlsRxDevice`` -
+  number of TX and RX sessions opened with NIC cryptography

include/uapi/linux/snmp.h

@@ -327,6 +327,14 @@ enum
 enum
 {
 	LINUX_MIB_TLSNUM = 0,
+	LINUX_MIB_TLSCURRTXSW,			/* TlsCurrTxSw */
+	LINUX_MIB_TLSCURRRXSW,			/* TlsCurrRxSw */
+	LINUX_MIB_TLSCURRTXDEVICE,		/* TlsCurrTxDevice */
+	LINUX_MIB_TLSCURRRXDEVICE,		/* TlsCurrRxDevice */
+	LINUX_MIB_TLSTXSW,			/* TlsTxSw */
+	LINUX_MIB_TLSRXSW,			/* TlsRxSw */
+	LINUX_MIB_TLSTXDEVICE,			/* TlsTxDevice */
+	LINUX_MIB_TLSRXDEVICE,			/* TlsRxDevice */
 	__LINUX_MIB_TLSMAX
 };
 

net/tls/tls_main.c

@@ -286,14 +286,19 @@ static void tls_sk_proto_cleanup(struct sock *sk,
 		kfree(ctx->tx.rec_seq);
 		kfree(ctx->tx.iv);
 		tls_sw_release_resources_tx(sk);
+		TLS_DEC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXSW);
 	} else if (ctx->tx_conf == TLS_HW) {
 		tls_device_free_resources_tx(sk);
+		TLS_DEC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXDEVICE);
 	}
 
-	if (ctx->rx_conf == TLS_SW)
+	if (ctx->rx_conf == TLS_SW) {
 		tls_sw_release_resources_rx(sk);
-	else if (ctx->rx_conf == TLS_HW)
+		TLS_DEC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXSW);
+	} else if (ctx->rx_conf == TLS_HW) {
 		tls_device_offload_cleanup_rx(sk);
+		TLS_DEC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXDEVICE);
+	}
 }
 
 static void tls_sk_proto_close(struct sock *sk, long timeout)
@@ -534,19 +539,29 @@ static int do_tls_setsockopt_conf(struct sock *sk, char __user *optval,
 	if (tx) {
 		rc = tls_set_device_offload(sk, ctx);
 		conf = TLS_HW;
-		if (rc) {
+		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, ctx, 1);
 			if (rc)
 				goto err_crypto_info;
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXSW);
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXSW);
 			conf = TLS_SW;
 		}
 	} else {
 		rc = tls_set_device_offload_rx(sk, ctx);
 		conf = TLS_HW;
-		if (rc) {
+		if (!rc) {
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXDEVICE);
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXDEVICE);
+		} else {
 			rc = tls_set_sw_offload(sk, ctx, 0);
 			if (rc)
 				goto err_crypto_info;
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXSW);
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXSW);
 			conf = TLS_SW;
 		}
 		tls_sw_strparser_arm(sk, ctx);

net/tls/tls_proc.c

@@ -7,6 +7,14 @@
 #include <net/tls.h>
 
 static const struct snmp_mib tls_mib_list[] = {
+	SNMP_MIB_ITEM("TlsCurrTxSw", LINUX_MIB_TLSCURRTXSW),
+	SNMP_MIB_ITEM("TlsCurrRxSw", LINUX_MIB_TLSCURRRXSW),
+	SNMP_MIB_ITEM("TlsCurrTxDevice", LINUX_MIB_TLSCURRTXDEVICE),
+	SNMP_MIB_ITEM("TlsCurrRxDevice", LINUX_MIB_TLSCURRRXDEVICE),
+	SNMP_MIB_ITEM("TlsTxSw", LINUX_MIB_TLSTXSW),
+	SNMP_MIB_ITEM("TlsRxSw", LINUX_MIB_TLSRXSW),
+	SNMP_MIB_ITEM("TlsTxDevice", LINUX_MIB_TLSTXDEVICE),
+	SNMP_MIB_ITEM("TlsRxDevice", LINUX_MIB_TLSRXDEVICE),
 	SNMP_MIB_SENTINEL
 };