From 251fa2dcc814ef51816245336fd1884239dd002a Mon Sep 17 00:00:00 2001
From: Tatiana Bradley <tatiana@golang.org>
Date: Thu, 12 May 2022 14:58:29 -0400
Subject: [PATCH 09/10] [release-branch.go1.17] crypto/tls: randomly generate
 ticket_age_add

As required by RFC 8446, section 4.6.1, ticket_age_add now holds a
random 32-bit value. Before this change, this value was always set
to 0.

This change also documents the reasoning for always setting
ticket_nonce to 0. The value ticket_nonce must be unique per
connection, but we only ever send one ticket per connection.

Updates #52814
Fixes #52832
Fixes CVE-2022-30629

Change-Id: I6c2fc6ca0376b7b968abd59d6d3d3854c1ab68bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/405994
Reviewed-by: Tatiana Bradley <tatiana@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Run-TryBot: Tatiana Bradley <tatiana@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
(cherry picked from commit fe4de36198794c447fbd9d7cc2d7199a506c76a5)
Reviewed-on: https://go-review.googlesource.com/c/go/+/408574
Run-TryBot: Roland Shoemaker <roland@golang.org>

Conflict: NA
Reference: https://go-review.googlesource.com/c/go/+/408574
---
 src/crypto/tls/handshake_server_tls13.go | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/crypto/tls/handshake_server_tls13.go b/src/crypto/tls/handshake_server_tls13.go
index 92d55e0293a..fcea739b9a9 100644
--- a/src/crypto/tls/handshake_server_tls13.go
+++ b/src/crypto/tls/handshake_server_tls13.go
@@ -9,6 +9,7 @@ import (
 	"crypto"
 	"crypto/hmac"
 	"crypto/rsa"
+	"encoding/binary"
 	"errors"
 	"hash"
 	"io"
@@ -742,6 +743,19 @@ func (hs *serverHandshakeStateTLS13) sendSessionTickets() error {
 	}
 	m.lifetime = uint32(maxSessionTicketLifetime / time.Second)
 
+	// ticket_age_add is a random 32-bit value. See RFC 8446, section 4.6.1
+	// The value is not stored anywhere; we never need to check the ticket age
+	// because 0-RTT is not supported.
+	ageAdd := make([]byte, 4)
+	_, err = hs.c.config.rand().Read(ageAdd)
+	if err != nil {
+		return err
+	}
+	m.ageAdd = binary.LittleEndian.Uint32(ageAdd)
+
+	// ticket_nonce, which must be unique per connection, is always left at
+	// zero because we only ever send one ticket per connection.
+
 	if _, err := c.writeRecord(recordTypeHandshake, m.marshal()); err != nil {
 		return err
 	}
-- 
2.30.2

