upstream commit

Remove support for pre-authentication compression. Doing
compression early in the protocol probably seemed reasonable in the 1990s,
but today it's clearly a bad idea in terms of both cryptography (cf. multiple
compression oracle attacks in TLS) and attack surface.

Moreover, to support it across privilege-separation zlib needed
the assistance of a complex shared-memory manager that made the
required attack surface considerably larger.

Prompted by Guido Vranken pointing out a compiler-elided security
check in the shared memory manager found by Stack
(http://css.csail.mit.edu/stack/); ok deraadt@ markus@

NB. pre-auth authentication has been disabled by default in sshd
for >10 years.

Upstream-ID: 32af9771788d45a0779693b41d06ec199d849caf

1 files changed, 2 insertions, 2 deletions

diff --git a/myproposal.h b/myproposal.h
index 4729b30b0..072e36ec7 100644
--- a/myproposal.h
+++ b/myproposal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: myproposal.h,v 1.53 2016/09/22 17:52:53 djm Exp $ */
+/* $OpenBSD: myproposal.h,v 1.54 2016/09/28 16:33:07 djm Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -167,7 +167,7 @@
 
 #endif /* WITH_OPENSSL */
 
-#define KEX_DEFAULT_COMP        "none,zlib@openssh.com,zlib"
+#define KEX_DEFAULT_COMP        "none,zlib@openssh.com"
 #define KEX_DEFAULT_LANG        ""
 
 #define KEX_CLIENT \