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6c61b27496
When the proxy re-encrypted a TLSv1.3 record it was adding a spurious byte onto the end. This commit removes that. The "extra" byte was intended to be the inner content type of the record. However, TLSProxy was actually adding the original encrypted data into the record (which already has the inner content type in it) and then adding the spurious additional content type byte on the end (and adjusting the record length accordingly). It is interesting to look at why this didn't cause a failure: The receiving peer first attempts to decrypt the data. Because this is TLSProxy we always use a GCM based ciphersuite with a 16 byte tag. When we decrypt this it actually gets diverted to the ossltest engine. All this does is go through the motions of encrypting/decrypting but just passes back the original data. Crucially it will never fail because of a bad tag! The receiving party thinks the spurious additional byte is part of the tag and the ossltest engine ignores it. This means the data that gets passed back to the record layer still has an additional spurious byte on it - but because the 16 byte tag has been removed, this is actually the first byte of the original tag. Again because we are using ossltest engine we aren't actually creating "real" tags - we only ever emit 16, 0 bytes for the tag. So the spurious additional byte always has the value 0. The TLSv1.3 spec says that records can have additional 0 bytes on the end of them - this is "padding". So the record layer interprets this 0 byte as padding and strips it off to end up with the originally transmitted record data - which it can now process successfully. Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de> (Merged from https://github.com/openssl/openssl/pull/5370) |
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OpenSSL 1.1.1-pre2-dev
Copyright (c) 1998-2018 The OpenSSL Project
Copyright (c) 1995-1998 Eric A. Young, Tim J. Hudson
All rights reserved.
DESCRIPTION
-----------
The OpenSSL Project is a collaborative effort to develop a robust,
commercial-grade, fully featured, and Open Source toolkit implementing the
Transport Layer Security (TLS) protocols (including SSLv3) as well as a
full-strength general purpose cryptographic library.
OpenSSL is descended from the SSLeay library developed by Eric A. Young
and Tim J. Hudson. The OpenSSL toolkit is licensed under a dual-license (the
OpenSSL license plus the SSLeay license), which means that you are free to
get and use it for commercial and non-commercial purposes as long as you
fulfill the conditions of both licenses.
OVERVIEW
--------
The OpenSSL toolkit includes:
libssl (with platform specific naming):
Provides the client and server-side implementations for SSLv3 and TLS.
libcrypto (with platform specific naming):
Provides general cryptographic and X.509 support needed by SSL/TLS but
not logically part of it.
openssl:
A command line tool that can be used for:
Creation of key parameters
Creation of X.509 certificates, CSRs and CRLs
Calculation of message digests
Encryption and decryption
SSL/TLS client and server tests
Handling of S/MIME signed or encrypted mail
And more...
INSTALLATION
------------
See the appropriate file:
INSTALL Linux, Unix, Windows, OpenVMS, ...
NOTES.* INSTALL addendums for different platforms
SUPPORT
-------
See the OpenSSL website www.openssl.org for details on how to obtain
commercial technical support. Free community support is available through the
openssl-users email list (see
https://www.openssl.org/community/mailinglists.html for further details).
If you have any problems with OpenSSL then please take the following steps
first:
- Download the latest version from the repository
to see if the problem has already been addressed
- Configure with no-asm
- Remove compiler optimization flags
If you wish to report a bug then please include the following information
and create an issue on GitHub:
- OpenSSL version: output of 'openssl version -a'
- Configuration data: output of 'perl configdata.pm --dump'
- OS Name, Version, Hardware platform
- Compiler Details (name, version)
- Application Details (name, version)
- Problem Description (steps that will reproduce the problem, if known)
- Stack Traceback (if the application dumps core)
Just because something doesn't work the way you expect does not mean it
is necessarily a bug in OpenSSL. Use the openssl-users email list for this type
of query.
HOW TO CONTRIBUTE TO OpenSSL
----------------------------
See CONTRIBUTING
LEGALITIES
----------
A number of nations restrict the use or export of cryptography. If you
are potentially subject to such restrictions you should seek competent
professional legal advice before attempting to develop or distribute
cryptographic code.