From c15a8e2dbb5ac376a6ed890735341b812d6b965c Mon Sep 17 00:00:00 2001 From: Tatiana Bradley Date: Thu, 12 May 2022 14:58:29 -0400 Subject: [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 Reviewed-by: Roland Shoemaker Run-TryBot: Tatiana Bradley TryBot-Result: Gopher Robot (cherry picked from commit fe4de36198794c447fbd9d7cc2d7199a506c76a5) Reviewed-on: https://go-review.googlesource.com/c/go/+/408574 Run-TryBot: Roland Shoemaker --- 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 08251b84de..6aa52698a3 100644 --- a/src/crypto/tls/handshake_server_tls13.go +++ b/src/crypto/tls/handshake_server_tls13.go @@ -10,6 +10,7 @@ import ( "crypto" "crypto/hmac" "crypto/rsa" + "encoding/binary" "errors" "hash" "io" @@ -741,6 +742,19 @@ 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 } -- cgit v1.2.3-54-g00ecf