[Bug 1051892] Re: [Quantal] Regression in TLS 1.2 workarounds

[Tyler Hicks]

I haven't attached a debdiff because it still isn't clear to me if
calling TLS1_get_client_version() is the correct thing to do here. We
probably need to open an upstream bug and get their opinion. I am
willing to do that tomorrow.

** Changed in: openssl (Ubuntu)
     Assignee: (unassigned) => Tyler Hicks (tyhicks)

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to openssl in Ubuntu.
https://bugs.launchpad.net/bugs/1051892

Title:
  [Quantal] Regression in TLS 1.2 workarounds

Status in “openssl” package in Ubuntu:
  Triaged

Bug description:
  openssl 1.0.1c-3ubuntu1 dropped almost all of
  debian/patches/tls12_workarounds.patch because the upstream 1.0.1c
  release contained the changes.

  However, the dropped pieces of tls12_workarounds.patch had a subtle
  difference from upstream. In the Ubuntu patch, ssl23_client_hello()
  checked the *client* TLS version when deciding if the cipher list
  should be truncated or not for TLS 1.2. The upstream code checks the
  *server* TLS version, which I believe is incorrect since the
  ServerHello hasn't even occurred yet. The upstream commit can be found
  here:

  http://cvs.openssl.org/chngview?cn=22408

  The change from TLS1_get_versions() to TLS1_get_client_versions() was
  discussed here:

  https://bugs.launchpad.net/ubuntu/+source/openssl/+bug/986147/comments/4

  This bug can be reproduced with the following command:

  $ openssl s_client -connect d2chzxaqi4y7f8.cloudfront.net:443 -CApath
  /etc/ssl/certs/

  It will fail unless -tls1 is specified like so:

  $ openssl s_client -connect d2chzxaqi4y7f8.cloudfront.net:443 -CApath
  /etc/ssl/certs/ -tls1

  Making this change fixes the problem (ssl3_client_hello() will
  probably need the same change):

  --- openssl-1.0.1c.orig/ssl/s23_clnt.c  2012-09-17 01:06:06.584617683 -0700
  +++ openssl-1.0.1c/ssl/s23_clnt.c       2012-09-17 02:09:01.140540223 -0700
  @@ -491,7 +491,7 @@
                           * as hack workaround chop number of supported ciphers
                           * to keep it well below this if we use TLS v1.2
                           */
  -                       if (TLS1_get_version(s) >= TLS1_2_VERSION
  +                       if (TLS1_get_client_version(s) >= TLS1_2_VERSION
                                  && i > OPENSSL_MAX_TLS1_2_CIPHER_LENGTH)
                                  i = OPENSSL_MAX_TLS1_2_CIPHER_LENGTH & ~1;
   #endif

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/openssl/+bug/1051892/+subscriptions