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, 18 insertions, 5 deletions

diff --git a/pbuilderrc b/pbuilderrc
index 6ade93b..8774f46 100644
--- a/pbuilderrc
+++ b/pbuilderrc
@@ -53,11 +53,19 @@ PBUILDERROOTCMD="sudo -E"
 # not support unsigned APT repositories
 PBUILDERSATISFYDEPENDSCMD="/usr/lib/pbuilder/pbuilder-satisfydepends"
 
-# You can optionally make pbuilder check key by setting the following flags
-# PBUILDERSATISFYDEPENDSOPT=('--check-key')
-# unset PBUILDERSATISFYDEPENDSOPT
-# option to pass to apt-get always.
-export APTGETOPT=('--force-yes')
+# Arguments for $PBUILDERSATISFYDEPENDSCMD.
+# PBUILDERSATISFYDEPENDSOPT=()
+
+# You can optionally make pbuilder accept untrusted repositories by setting
+# this option to yes, but this may allow remote attackers to compromise the
+# system. Better set a valid key for the signed (local) repository with
+# $APTKEYRINGS (see below).
+ALLOWUNTRUSTED=no
+
+# Option to pass to apt-get always.
+export APTGETOPT=()
+# Option to pass to aptitude always.
+export APTITUDEOPT=()
 
 #Command-line option passed on to dpkg-buildpackage.
 #DEBBUILDOPTS="-IXXX -iXXX"
@@ -82,6 +90,11 @@ DEBOOTSTRAPOPTS=(
 # or unset it to make it not a buildd type.
 # unset DEBOOTSTRAPOPTS
 
+# Keyrings to use for package verification with apt, not used for debootstrap
+# (use DEBOOTSTRAPOPTS). By default the debian-archive-keyring package inside
+# the chroot is used.
+APTKEYRINGS=()
+
 # Set the PATH I am going to use inside pbuilder: default is "/usr/sbin:/usr/bin:/sbin:/bin"
 export PATH="/usr/sbin:/usr/bin:/sbin:/bin"