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[Launchpad Bug Tracker <1903776@xxxxxxxxxxxxxxxxxx>]

** Merge proposal linked:
   https://code.launchpad.net/~simpoir/ubuntu/+source/landscape-client/+git/landscape-client/+merge/415626

** Merge proposal linked:
   https://code.launchpad.net/~simpoir/ubuntu/+source/landscape-client/+git/landscape-client/+merge/415627

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https://bugs.launchpad.net/bugs/1903776

Title:
  Changed ubuntu-keyring paths breaks upgrade to focal.

Status in Landscape Client:
  Fix Committed
Status in landscape-client package in Ubuntu:
  In Progress
Status in landscape-client source package in Bionic:
  In Progress
Status in landscape-client source package in Focal:
  In Progress
Status in landscape-client source package in Groovy:
  Won't Fix
Status in landscape-client source package in Hirsute:
  In Progress
Status in landscape-client source package in Impish:
  New
Status in landscape-client source package in Jammy:
  In Progress

Bug description:
  [Impact]

   * When launching an Ubuntu release-upgrade through landscape-client, the
     upgrade-tool fails GPG verification due to trusted apt key having changed
     location as of 18.04 LTS.

   * The proposed patch extends gpg lookup path to include all
     /etc/apt/trusted.gpg.d/*.gpg files in addition to /etc/apt/trusted.gpg
     when verifying the upgrade-tool signature.

  [Test Case]

   * Install and register the landscape-client against a landscape-server
     on a series supporting an upgrade.

   * Wait for it to sync up packages.

   * On the computer packages page, there is a link at the bottom to request a
     release upgrade of that machine, if a supported version is available.

   * The upgrade fails and /var/log/landscape/release-upgrader.log will indicate
     a failed gpg verification.

  [Where problems could occur]

   * One thing which has been considered in this fix is how someone could have
     worked around the issue by re-creating the old key path. The fix covers
     such a case by still reading the deprecated trusted.gpg file.

   * Although some care has been taken to only load valid gpg keys from apt
     trusted keychain, there could be unforeseen scenarios where invalid data
     gets read from the keychain. In such a case, the strict nature of gpg would
     reject the signature verification, thus being no worse than without the fix.

   * The affected callsite is used for verifying the release-upgrader code prior
     to running it. One bad thing which we could imagine with this code path is
     falsely accepting an invalid file signature, which may create a security
     issue. This would likely take shape of injecting a gpg key, without
     having root access, in the search path.

  [Other Info]

   * There is no way to directly verify this issue on 20.10 Groovy and later
     (without faking a release) due to the lack of upgrade path to a supported
     LTS. The ubuntu-keyring package having the same file layout, the same
     validation failure is however to be expected if left unpatched.

  [Original description]

  Since bionic, ubuntu-keyring removed `/etc/apt/trusted.gpg` in favor
  of `/etc/apt/trusted.gpg.d/`

  This breaks signature verification for the upgrade-tool.
  Trying to release-upgrade through landscape yields a failure on signature check:

  2020-11-10 15:47:51,019 WARNING  [MainThread] Invalid signature for upgrade-tool tarball: /usr/bin/gpg failed (out='', err='gpg: keybox '/etc/apt/trusted.gpg' created
  gpg: Signature made Fri Oct 16 03:28:09 2020 UTC
  gpg:                using RSA key 3B4FE6ACC0B21F32
  gpg: Can't check signature: No public key

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