Bug#579028: pbuilder: installs untrusted packages without asking

Package: pbuilder
Version: 0.206
Tags: patch
Followup-For: Bug #579028

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Hash: SHA256

Dear Maintainer,

The attached patch changes the defaults to always enforce signed
repositories and aborts if an untrusted/manipulated package is
installed. It adds the new option --keyring (APTKEYRINGS) to add
additional keyrings, which are then used to verify the (local)
signed repositories. This way no untrusted packages can be
installed.

To still allow untrusted/unsigned repositories - they are a very
bad idea and allow remote attackers performing a MITM to take
over the system, including all built packages - the new option
- --allow-untrusted (ALLOWUNTRUSTED) was added.

I tested it with the official Debian repository, signed and
unsigned local repositories and it works fine for me. But I'm
only a "normal" pbuilder user, so I might have missed something.
Please test the patch.

I haven't tested it with cdebootstrap, but it should work as
well.

The old PBUILDERSATISFYDEPENDSOPT --check-key option was
deprecated and is no longer used (it emits a warning now) as
validation is the default now.

The patch also contains documentation updates for the new
options/variables and updates for the NEWS file describing the
necessary changes to continue using untrusted packages (but
please don't do that - especially as a Debian developer).

Please have a look and include the patch as soon as possible to
fix this security issue.

Regards,
Simon

- -- System Information:
Debian Release: wheezy/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages pbuilder depends on:
ii  cdebootstrap           0.5.8+b1
ii  coreutils              8.13-3
ii  debconf [debconf-2.0]  1.5.41
ii  debianutils            4.2.1
ii  debootstrap            1.0.38
ii  dpkg-dev               1.16.1.2
ii  wget                   1.13.4-2

Versions of packages pbuilder recommends:
pn  devscripts  2.11.4
pn  fakeroot    1.18.2-1
pn  sudo        <none>

Versions of packages pbuilder suggests:
pn  cowdancer     <none>
pn  gdebi-core    <none>
pn  pbuilder-uml  <none>

- -- debconf information excluded

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>From cadc48fb599d436577a6efedc7f25e175652a3a1 Mon Sep 17 00:00:00 2001
Message-Id: <cadc48fb599d436577a6efedc7f25e175652a3a1.1330997290.git.simon@ruderich.org>
From: Simon Ruderich <simon@ruderich.org>
Date: Tue, 6 Mar 2012 02:00:48 +0100
Subject: [PATCH] Enforce valid signed repositories by default.

1 files changed, 6 insertions, 0 deletions

diff --git a/pbuilder-updatebuildenv b/pbuilder-updatebuildenv
index cdcc22c..737f53d 100755
--- a/pbuilder-updatebuildenv
+++ b/pbuilder-updatebuildenv
@@ -72,6 +72,12 @@ $CHROOTEXEC /usr/bin/apt-get -q -y "${APTGETOPT[@]}" autoremove || true
 $CHROOTEXEC /usr/bin/apt-get -q -y "${APTGETOPT[@]}" install build-essential dpkg-dev $EXTRAPACKAGES
 save_aptcache
 
+# To support package verification inside the repository we may have to import
+# additional keys.
+for KEY in "${APTKEYRINGS[@]}"; do
+    $CHROOTEXEC /usr/bin/apt-key add - < "${KEY}" > /dev/null
+done
+
 # optionally auto-clean apt-cache
 if [ "${AUTOCLEANAPTCACHE}" = "yes" -a -n "$APTCACHE" ]; then
     log "I: Cleaning the cached apt archive"