[Bug 423252] Re: NSS using LDAP+SSL breaks setuid applications like su, sudo, apache2 suexec, and atd

[nutznboltz]

According to Andreas Metzler
http://lists.debian.org/debian-legal/2011/02/msg00006.html
{{ GnuTLS upstream has added support for different crypto backends in
2.11.x and has chosen nettle as prefered backend (2.10.x is using
libgcrypt). }}

I have started to experiment with using a gnutls26 package with nettle
instead of libgcrypt11 on Ubuntu 12.04.

I have yet to adjust the gnutls26 package dependencies, at this point
I just cheat and install nettle-dev manually:

sudo apt-get install nettle-dev

Then I

apt-get source gnutls26

to fetch the source for gnutls26-2.12.14

chop out
--with-libgcrypt
from debian/rules

bump the package version in debian/changelog to 2.12.14-5ubuntu2.1

and rebuild with

debuild -i -uc -us -b

then I put a checkpoint on the VM and install the package:

dpkg -i libgnutls26_2.12.14-5ubuntu2.1_amd64.deb

but then sudo works on my LDAP+SSL client.

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https://bugs.launchpad.net/bugs/423252

Title:
  NSS using LDAP+SSL breaks setuid applications like su, sudo, apache2
  suexec, and atd

Status in Release Notes for Ubuntu:
  Fix Released
Status in “eglibc” package in Ubuntu:
  Invalid
Status in “libgcrypt11” package in Ubuntu:
  Confirmed
Status in “libnss-ldap” package in Ubuntu:
  Invalid
Status in “sudo” package in Ubuntu:
  Invalid
Status in “eglibc” source package in Lucid:
  Invalid
Status in “libgcrypt11” source package in Lucid:
  Confirmed
Status in “libnss-ldap” source package in Lucid:
  Invalid
Status in “sudo” source package in Lucid:
  Invalid
Status in “eglibc” source package in Maverick:
  Invalid
Status in “libgcrypt11” source package in Maverick:
  Confirmed
Status in “libnss-ldap” source package in Maverick:
  Confirmed
Status in “sudo” source package in Maverick:
  Invalid
Status in “eglibc” source package in Karmic:
  Invalid
Status in “libgcrypt11” source package in Karmic:
  Won't Fix
Status in “libnss-ldap” source package in Karmic:
  Invalid
Status in “sudo” source package in Karmic:
  Invalid
Status in “libgcrypt11” package in Debian:
  Confirmed
Status in “sudo” package in Debian:
  Confirmed
Status in “sudo” package in Kairos Linux:
  Confirmed

Bug description:
  On Karmic (alpha 4 plus updates), changing the nsswitch.conf 'passwd'
  field to anything with 'ldap' as the first item breaks the ability to
  become root using 'su' and 'sudo' as anyone but root.

  Default nsswitch.conf:

  passwd:         compat
  group:          compat
  shadow:         compat

  matt at box:~$ sudo uname -a
  [sudo] password for matt:
  Linux box 2.6.31-9-server #29-Ubuntu SMP Sun Aug 30 18:37:42 UTC 2009 x86_64 GNU/Linux

  matt at box:~$ su -
  Password:
  root at box:~#

  Modified nsswitch.conf with 'ldap' before 'compat':

  passwd:         ldap compat
  group:          ldap compat
  shadow:         ldap compat

  matt at box:~$ sudo uname -a
  sudo: setreuid(ROOT_UID, user_uid): Operation not permitted

  matt at box:~$ su -
  Password:
  setgid: Operation not permitted

  Modified nsswitch.conf with 'ldap' after 'compat':

  passwd:         compat ldap
  group:          compat ldap
  shadow:         compat ldap

  matt at box:~$ sudo uname -a
  [sudo] password for matt:
  Linux box 2.6.31-9-server #29-Ubuntu SMP Sun Aug 30 18:37:42 UTC 2009 x86_64 GNU/Linux

  matt at box:~$ su -
  Password:
  root at box:~#

  The same arrangements in nsswitch.conf work as expected in Jaunty and
  earlier releases.

  Lucid Release Note:

  == NSS via LDAP+SSL breaks setuid applications like sudo ==

  Upgrading systems configured to use ldap over ssl as the first service
  in the nss stack (in nsswitch.conf) leads to a broken nss resolution
  for setuid applications after the upgrade to Lucid (for example sudo
  would stop working). There isn't any simple workaround for now. One
  option is to switch to libnss-ldapd in place of libnss-ldap before the
  upgrade. Another one consists in using nscd before the upgrade.

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