Your message dated Fri, 02 Jan 2015 12:40:16 +0000
with message-id <e1y71wa-0003es...@franck.debian.org>
and subject line Bug#767610: Removed package(s) from unstable
has caused the Debian Bug report #737921,
regarding gnutls unusable with cacert SHA2-512 sigs
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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-- 
737921: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=737921
Debian Bug Tracking System
Contact ow...@bugs.debian.org with problems
--- Begin Message ---
Package: libgnutls26
Severity: serious
Version: 2.12.20-8


cacert.org recently started signing certs with sha512WithRSAEncryption

Consider the following scenario:

- some service running on a Debian stable (wheezy) host (e.g. slapd),
admin replaces their cacert certificate with one of these new certs

- clients (e.g. PAM LDAP module, Apache mod_authnz_ldap) on Debian hosts
linked against gnutls

Everything stops working when the replacement certificate is installed

Troubleshooting, the following is observed:

- running ldapsearch or similar commands, the user sees errors like:
    ldap_sasl_bind(SIMPLE): Can't contact LDAP server (-1)
or with "-d 1" for debugging, there is more detail but it doesn't help:

TLS: can't connect: A TLS packet with unexpected length was received..
ldap_err2string
ldap_sasl_bind(SIMPLE): Can't contact LDAP server (-1)

- the user then tries openssl s_client

openssl s_client -connect ldap-host.example.org:636 -tls1 -CAfile
/etc/ssl/certs/cacert.org.pem

and it connects successfully

- if the user also tries gnutls-cli however, it does not work, failing
with errors like this:

      GnuTLS error: A TLS packet with unexpected length was received.

- then the admin tries putting their server (e.g. slapd) in debug mode
and sees errors like this

    Could not negotiate a supported cipher suite

- the fact that openssl s_client worked and gnutls-cli did not work may
leave them feeling it is gnutls problems again (a Google search finds
plenty of old posts complaining about gnutls and suggesting people
should recompile everything with openssl)

- running gnutls-cli in debug mode, I notice the following:

$ gnutls-cli -p 636 --priority NORMAL:+SIGN-RSA-SHA512 -d 255
ldap-host.example.org

|<2>| EXT[SIGA]: sent signature algo (4.2) DSA-SHA256
|<2>| EXT[SIGA]: sent signature algo (4.1) RSA-SHA256
|<2>| EXT[SIGA]: sent signature algo (2.1) RSA-SHA1
|<2>| EXT[SIGA]: sent signature algo (2.2) DSA-SHA1

Even explicitly requesting SHA512 doesn't help:

    gnutls-cli -p 636 --priority NORMAL:+SIGN-RSA-SHA512 -d 255
ldap-host.example.org

It seems that the gnutls client code in wheezy does not signal support
for the SHA512 stuff in the client hello message even if it is requested
in the cipher suite


$   gnutls-cli --list | grep 512
MACs: SHA1, MD5, SHA256, SHA384, SHA512, MD2, RIPEMD160, MAC-NULL
PK-signatures: SIGN-RSA-SHA1, SIGN-RSA-SHA224, SIGN-RSA-SHA256,
SIGN-RSA-SHA384, SIGN-RSA-SHA512, SIGN-RSA-RMD160, SIGN-DSA-SHA1,
SIGN-DSA-SHA224, SIGN-DSA-SHA256, SIGN-RSA-MD5, SIGN-RSA-MD2

suggests that the RSA-SHA512 is present and should work, but it doesn't

This is likely to be particularly annoying for people to troubleshoot,
especially if they have only allocated 5-10 minutes to replace their
certificate and they end up spending hours digging through their logs
and pulling their hair out before they realize what is wrong


Looking at the connections with tcpdump, I notice:
- client sends SSL client hello
- server drops connection without sending more data back to client

A suggested workaround is for the admin to create their own local root
CA instead of relying on CA cert.  That means that the admin can ensure
that any changes to CA policy (e.g. using SHA512) are tested before
being forced on people.

--- End Message ---
--- Begin Message ---
Version: 2.12.23-17+rm

Dear submitter,

as the package gnutls26 has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/767610

The version of this package that was in Debian prior to this removal
can still be found using http://snapshot.debian.org/.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmas...@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Scott Kitterman (the ftpmaster behind the curtain)

--- End Message ---

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