tls: add counters for rekey

This introduces 5 counters to keep track of key updates:
Tls{Rx,Tx}Rekey{Ok,Error} and TlsRxRekeyReceived.

Suggested-by: Jakub Kicinski <[e-mail]>
Signed-off-by: Sabrina Dubroca <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/uapi/linux/snmp.h

···
 	LINUX_MIB_TLSRXDEVICERESYNC,		/* TlsRxDeviceResync */
 	LINUX_MIB_TLSDECRYPTRETRY,		/* TlsDecryptRetry */
 	LINUX_MIB_TLSRXNOPADVIOL,		/* TlsRxNoPadViolation */
+	LINUX_MIB_TLSRXREKEYOK,			/* TlsRxRekeyOk */
+	LINUX_MIB_TLSRXREKEYERROR,		/* TlsRxRekeyError */
+	LINUX_MIB_TLSTXREKEYOK,			/* TlsTxRekeyOk */
+	LINUX_MIB_TLSTXREKEYERROR,		/* TlsTxRekeyError */
+	LINUX_MIB_TLSRXREKEYRECEIVED,		/* TlsRxRekeyReceived */
 	__LINUX_MIB_TLSMAX
 };
 

net/tls/tls_main.c

···
 		/* Currently we only support setting crypto info more
 		 * than one time for TLS 1.3
 		 */
-		if (crypto_info->version != TLS_1_3_VERSION)
+		if (crypto_info->version != TLS_1_3_VERSION) {
+			TLS_INC_STATS(sock_net(sk), tx ? LINUX_MIB_TLSTXREKEYERROR
+						       : LINUX_MIB_TLSRXREKEYERROR);
 			return -EBUSY;
+		}
 
 		update = true;
 		old_crypto_info = crypto_info;
···
 						update ? crypto_info : NULL);
 			if (rc)
 				goto err_crypto_info;
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXSW);
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXSW);
+
+			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);
+			}
 			conf = TLS_SW;
 		}
 	} else {
···
 						update ? crypto_info : NULL);
 			if (rc)
 				goto err_crypto_info;
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXSW);
-			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXSW);
+
+			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);
+			}
 			conf = TLS_SW;
 		}
 		if (!update)
···
 	return 0;
 
 err_crypto_info:
+	if (update) {
+		TLS_INC_STATS(sock_net(sk), tx ? LINUX_MIB_TLSTXREKEYERROR
+					       : LINUX_MIB_TLSRXREKEYERROR);
+	}
 	memzero_explicit(crypto_ctx, sizeof(*crypto_ctx));
 	return rc;
 }

net/tls/tls_proc.c

···
 	SNMP_MIB_ITEM("TlsRxDeviceResync", LINUX_MIB_TLSRXDEVICERESYNC),
 	SNMP_MIB_ITEM("TlsDecryptRetry", LINUX_MIB_TLSDECRYPTRETRY),
 	SNMP_MIB_ITEM("TlsRxNoPadViolation", LINUX_MIB_TLSRXNOPADVIOL),
+	SNMP_MIB_ITEM("TlsRxRekeyOk", LINUX_MIB_TLSRXREKEYOK),
+	SNMP_MIB_ITEM("TlsRxRekeyError", LINUX_MIB_TLSRXREKEYERROR),
+	SNMP_MIB_ITEM("TlsTxRekeyOk", LINUX_MIB_TLSTXREKEYOK),
+	SNMP_MIB_ITEM("TlsTxRekeyError", LINUX_MIB_TLSTXREKEYERROR),
+	SNMP_MIB_ITEM("TlsRxRekeyReceived", LINUX_MIB_TLSRXREKEYRECEIVED),
 	SNMP_MIB_SENTINEL
 };
 

net/tls/tls_sw.c

···
 	return 1;
 }
 
-static int tls_check_pending_rekey(struct tls_context *ctx, struct sk_buff *skb)
+static int tls_check_pending_rekey(struct sock *sk, struct tls_context *ctx,
+				   struct sk_buff *skb)
 {
 	const struct strp_msg *rxm = strp_msg(skb);
 	const struct tls_msg *tlm = tls_msg(skb);
···
 		struct tls_sw_context_rx *rx_ctx = ctx->priv_ctx_rx;
 
 		WRITE_ONCE(rx_ctx->key_update_pending, true);
+		TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXREKEYRECEIVED);
 	}
 
 	return 0;
···
 	rxm->full_len -= prot->overhead_size;
 	tls_advance_record_sn(sk, prot, &tls_ctx->rx);
 
-	return tls_check_pending_rekey(tls_ctx, darg->skb);
+	return tls_check_pending_rekey(sk, tls_ctx, darg->skb);
 }
 
 int decrypt_skb(struct sock *sk, struct scatterlist *sgout)