netdev - [PATCH net-next 2/4] tls: rx: add counter for NoPad violations

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Date:   Fri,  8 Jul 2022 19:52:53 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
        borisp@...dia.com, john.fastabend@...il.com, maximmi@...dia.com,
        tariqt@...dia.com, Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 2/4] tls: rx: add counter for NoPad violations

As discussed with Maxim add a counter for true NoPad violations.
This should help deployments catch unexpected padded records vs
just control records which always need re-encryption.

https://lore.kernel.org/all/b111828e6ac34baad9f4e783127eba8344ac252d.camel@nvidia.com/
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 Documentation/networking/tls.rst | 4 ++++
 include/uapi/linux/snmp.h        | 1 +
 net/tls/tls_proc.c               | 1 +
 net/tls/tls_sw.c                 | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/Documentation/networking/tls.rst b/Documentation/networking/tls.rst
index 7a6643836e42..658ed3a71e1b 100644
--- a/Documentation/networking/tls.rst
+++ b/Documentation/networking/tls.rst
@@ -282,3 +282,7 @@ TLS implementation exposes the following per-namespace statistics
   number of RX records which had to be re-decrypted due to
   ``TLS_RX_EXPECT_NO_PAD`` mis-prediction. Note that this counter will
   also increment for non-data records.
+
+- ``TlsRxNoPadViolation`` -
+  number of data RX records which had to be re-decrypted due to
+  ``TLS_RX_EXPECT_NO_PAD`` mis-prediction.
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index fd83fb9e525a..4d7470036a8b 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -345,6 +345,7 @@ enum
 	LINUX_MIB_TLSDECRYPTERROR,		/* TlsDecryptError */
 	LINUX_MIB_TLSRXDEVICERESYNC,		/* TlsRxDeviceResync */
 	LINUX_MIB_TLSDECRYPTRETRY,		/* TlsDecryptRetry */
+	LINUX_MIB_TLSRXNOPADVIOL,		/* TlsRxNoPadViolation */
 	__LINUX_MIB_TLSMAX
 };
 
diff --git a/net/tls/tls_proc.c b/net/tls/tls_proc.c
index ede9df13c398..68982728f620 100644
--- a/net/tls/tls_proc.c
+++ b/net/tls/tls_proc.c
@@ -21,6 +21,7 @@ static const struct snmp_mib tls_mib_list[] = {
 	SNMP_MIB_ITEM("TlsDecryptError", LINUX_MIB_TLSDECRYPTERROR),
 	SNMP_MIB_ITEM("TlsRxDeviceResync", LINUX_MIB_TLSRXDEVICERESYNC),
 	SNMP_MIB_ITEM("TlsDecryptRetry", LINUX_MIB_TLSDECRYPTRETRY),
+	SNMP_MIB_ITEM("TlsRxNoPadViolation", LINUX_MIB_TLSRXNOPADVIOL),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index e12846d1871a..68d79ee48a56 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -1596,6 +1596,8 @@ 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;
+		if (!darg->tail)
+			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXNOPADVIOL);
 		TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSDECRYPTRETRY);
 		return decrypt_skb_update(sk, skb, dest, darg);
 	}
-- 
2.36.1