Unattended upgrades handles new dependencies inconsistently

[Sjoerd Job Postmus]

[Impact]

When an installed package adds a dependency that is not yet installed on the system, this sometimes causes the package to not be installed, depending on the origin containing the original candidate version.

I believe that the problem is in /usr/bin/unattended-upgrade, line 102. Here a check is performed to prevent downgrades. However, as a side effect it also prevents adjusting the candidate version for packages that have not yet been installed (because pkg.is_upgradable is False for packages that have not been installed).

This makes updating private packages using unattended-upgrades troublesome, especially when new dependencies have been added. Currently it requires repackaging the dependencies with a slightly higher version number than what is in the main repository, and then hosting them on the private repository, which is time consuming and error-prone. With the included patch, it is sufficient to just host the same version on the private repository.

[Test Case]

- Create a testing package (doesn't have to really contain anything) that just installs 1 file into /usr/share/testpackage/, and have it depend on some packages.
- Put that package on a private repository (which is also configured for APT and unattended-upgrades)
- Install the package using `apt-get install testingpackage`
- Update the package as follows: 1. Add a dependency which is not yet installed on your machine (and is also not in the security-repository). Up the version number, and add it to the private repository.
- Run `unattended-upgrade --debug --apt-debug 2>&1 | tee output.txt`.
- Verify the package was not updated (missing dependency).
- Host the dependency on your private APT server as well (1-1 copy).
- Run `unattended-upgrade --debug --apt-debug 2>&1 | tee output.txt`.
- Verify the package was not updated (missing dependency).
- Re-build the dependency with a higher version number, and add it to your private APT repository.
- Run `unattended-upgrade --debug --apt-debug 2>&1 | tee output.txt`.
- Verify the package was now upgraded.

With the proposed patch, the upgrade would already succeed after hosting the exact copy on the private APT repository.

[Regression Potential]

The changed code logic now allows adjusting candidates of packages which are not upgradable and not installed. Since the changed check was there to avoid downgrades the possible regression would be somehow enabling downgrades accidentally. Adjusting _not_ installed packages in itself would not cause downgrading installed packages thus the change seems to be safe.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "also_adjust_candidate_version_for_non_installed_packages.patch" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[Brian Murray (brian-murray)]

Do you happen to have an example of a package which I could test this with?

[Sjoerd Job Postmus (sjoerdjob-postmus)]

@BrianMurray: Not anymore, unfortunately.

How I originally reproduced it was:

- Create a testing package (doesn't have to really contain anything) that just installs 1 file into /usr/share/testpackage/, and have it depend on some packages.
- Put that package on a private repository (which is also configured for APT and unattended-upgrades)
- Install the package using `apt-get install testingpackage`
- Update the package as follows: 1. Add a dependency which is not yet installed on your machine (and is also not in the security-repository). Up the version number, and add it to the private repository.
- Run `unattended-upgrade --debug --apt-debug 2>&1 | tee output.txt`.
- Verify the package was not updated (missing dependency).
- Host the dependency on your private APT server as well (1-1 copy).
- Run `unattended-upgrade --debug --apt-debug 2>&1 | tee output.txt`.
- Verify the package was not updated (missing dependency).
- Re-build the dependency with a higher version number, and add it to your private APT repository.
- Run `unattended-upgrade --debug --apt-debug 2>&1 | tee output.txt`.
- Verify the package was now upgraded.

With the proposed patch, the upgrade would already succeed after hosting the exact copy on the private APT repository.

If needed I could probably figure out how to reproduce this again, but it would take me quite some time, as I'd have to set-up everything again. Hopefully my description of the case is enough for you to reproduce this.

Let me know if you need my help in reproducing.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unattended-upgrades - 0.99ubuntu2

---------------
unattended-upgrades (0.99ubuntu2) bionic; urgency=medium

  * Run upgrade-between-snapshots only on amd64.
    The test exercises only unattented-upgrade's Python code and uses
    dependencies from the frozen Debian snapshot archive thus running
    it on all architectures would provide little benefit.

 -- Balint Reczey <email address hidden> Tue, 13 Feb 2018 11:41:20 +0700

[Brian Murray (brian-murray)]

Hello Sjoerd, or anyone else affected,

Accepted unattended-upgrades into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unattended-upgrades/1.1ubuntu1.18.04.7~16.04.0 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Łukasz Zemczak (sil2100)]

Hello Sjoerd, or anyone else affected,

Accepted unattended-upgrades into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unattended-upgrades/1.1ubuntu1.18.04.7~16.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Łukasz Zemczak (sil2100)]

Hello Sjoerd, or anyone else affected,

Accepted unattended-upgrades into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unattended-upgrades/1.1ubuntu1.18.04.7~16.04.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Balint Reczey (rbalint)]

Verified 1.1ubuntu1.18.04.7~16.04.2 on Ubuntu Xenial.

I changed a different, but equivalent way of verifying the fix,
in /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-updates_main_binary-amd64_Packages I bumped the version of bash-doc to 4.3-14ubuntu1.3, bumped git's version in updates to 1:2.7.4-0ubuntu1.7 and made git depend on bash-doc (>= 4.3-14ubuntu1) in both -updates and -security.

Bash-doc was not installed originally on the system.

With unfixed u-u it fails to upgrade git:
root@x-uu-ref:~# unattended-upgrade --dry-run --verbose --debug
Initial blacklisted packages:
Initial whitelisted packages:
Starting unattended upgrades script
Allowed origins are: ['o=Ubuntu,a=xenial', 'o=Ubuntu,a=xenial-security', 'o=UbuntuESM,a=xenial']
Checking: git ([<Origin component:'main' archive:'xenial-updates' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
pkgs that look like they should be upgraded:
Fetched 0 B in 0s (0 B/s)
fetch.run() result: 0
blacklist: []
whitelist: []
No packages found that can be upgraded unattended and no pending auto-removals
root@x-uu-ref:~# vi /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-updates_main_binary-amd64_Packages
root@x-uu-ref:~# vi /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-updates_main_binary-amd64_Packages
root@x-uu-ref:~# unattended-upgrade --dry-run --verbose --debug
Initial blacklisted packages:
Initial whitelisted packages:
Starting unattended upgrades script
Allowed origins are: ['o=Ubuntu,a=xenial', 'o=Ubuntu,a=xenial-security', 'o=UbuntuESM,a=xenial']
adjusting candidate version: 'git=1:2.7.4-0ubuntu1.6'
Checking: git ([<Origin component:'main' archive:'xenial-security' origin:'Ubuntu' label:'Ubuntu' site:'security.ubuntu.com' isTrusted:True>])
pkg 'bash-doc' not in allowed origin
sanity check failed
adjusting candidate version: 'git=1:2.7.4-0ubuntu1.6'
pkgs that look like they should be upgraded:
Fetched 0 B in 0s (0 B/s)
fetch.run() result: 0
blacklist: []
whitelist: []
Option --dry-run given, *not* performing real actions
Packages that will be upgraded:
adjusting candidate version: 'git=1:2.7.4-0ubuntu1.6'
Packages that are auto removed: 'libfreetype6'
Packages were successfully auto-removed
InstCount=0 DelCount=0 BrokenCount=0

With fixed u-u, git is upgraded:
root@x-uu-verify:~# unattended-upgrade --dry-run --verbose --debug
Initial blacklisted packages:
Initial whitelisted packages:
Starting unattended upgrades script
Allowed origins are: o=Ubuntu,a=xenial, o=Ubuntu,a=xenial-security, o=UbuntuESM,a=xenial
Using (^linux-image-[0-9]+\.[0-9\.]+-.*|^linux-headers-[0-9]+\.[0-9\.]+-.*|^linux-image-extra-[0-9]+\.[0-9\.]+-.*|^linux-modules-[0-9]+\.[0-9\.]+-.*|^linux-modules-extra-[0-9]+\.[0-9\.]+-.*|^linux-signed-image-[0-9]+\.[0-9\.]+-.*|^kfreebsd-image-[0-9]+\.[0-9\.]+-.*|^kfreebsd-headers-[0-9]+\.[0-9\.]+-.*|^gnumach-image-[0-9]+\.[0-9\.]+-.*|^.*-modules-[0-9]+\.[0-9\.]+-.*|^.*-kernel-[0-9]+\.[0-9\.]+-.*|^linux-backports-modules-.*-[0-9]+\.[0-9\.]+-.*|...

[Launchpad Janitor (janitor)]

This bug was fixed in the package unattended-upgrades - 1.1ubuntu1.18.04.7~16.04.2

---------------
unattended-upgrades (1.1ubuntu1.18.04.7~16.04.2) xenial; urgency=medium

  * Don't check blacklist too early and report updates from not allowed origins
    as kept back. (LP: #1781176)
  * test/test_blacklisted_wrong_origin.py: Fix and enable test
  * Filter out progress indicator from dpkg log (LP: #1599646)
  * Clear cache when autoremoval fails (LP: #1779157)
  * Find autoremovable kernel packages using the patterns in APT's way
    (LP: #1815494)

unattended-upgrades (1.1ubuntu1.18.04.7~16.04.1) xenial; urgency=medium

  * Start service after systemd-logind.service to be able to take inhibition
    lock (LP: #1806487)
  * Handle gracefully when logind is down (LP: #1806487)

unattended-upgrades (1.1ubuntu1.18.04.7~16.04.0) xenial; urgency=medium

  * Backport to Xenial (LP: #1702793)
  * Revert to build-depending on debhelper (>= 9~) and dh-systemd
  * Revert configuration example changes to avoid triggering a debconf question
  * debian/postinst: Update recovery to be triggered on Xenial's package versions

unattended-upgrades (1.1ubuntu1.18.04.7) bionic; urgency=medium

  * Trigger unattended-upgrade-shutdown actions with PrepareForShutdown()
    Performing upgrades in service's ExecStop did not work when the upgrades
    involved restarting services because systemd blocked other stop/start
    actions making maintainer scripts time out and be killed leaving a broken
    system behind.
    Running unattended-upgrades.service before shutdown.target as a oneshot
    service made it run after unmounting filesystems and scheduling services
    properly on shutdown is a complex problem and adding more services to the
    mix make it even more fragile.
    The solution of monitoring PrepareForShutdown() signal from DBus
    allows Unattended Upgrade to run _before_ the jobs related to shutdown are
    queued thus package upgrades can safely restart services without
    risking causing deadlocks or breaking part of the shutdown actions.
    Also ask running unattended-upgrades to stop when shutdown starts even in
    InstallOnShutdown mode and refactor most of unattended-upgrade-shutdown to
    UnattendedUpgradesShutdown class. (LP: #1778219)
  * Increase logind's InhibitDelayMaxSec to 30s. (LP: #1778219)
    This allows more time for unattended-upgrades to shut down gracefully
    or even install a few packages in InstallOnShutdown mode, but is still a
    big step back from the 30 minutes allowed for InstallOnShutdown previously.
    Users enabling InstallOnShutdown node are advised to increase
    InhibitDelayMaxSec even further possibly to 30 minutes.
    - Add NEWS entry about increasing InhibitDelayMaxSec and InstallOnShutdown
      changes
  * Ignore "W503 line break before binary operator"
    because it will become the best practice and breaks the build
  * Stop using ActionGroups, they interfere with apt.Cache.clear()
    causing all autoremovable packages to be handled as newly autoremovable
    ones and be removed by default. Dropping ActionGroup usage does not slow
    down the most frequent case of not having anything to upgrade a...