[Bug 2060721] Re: APT 2.8.4+: Promote weak key warnings to errors

[Julian Andres Klode]

** Summary changed:

- APT 2.8.0: Promote weak key warnings to errors
+ APT 2.8.4+: Promote weak key warnings to errors

** Description changed:

+ (2.8.3 update references this bug as previous uploads tried to fix it
+ and have not been fully reverted, per discussion with rbasak we agreed
+ to just ignore this bug for SRU verification; as in mark it
+ verification-done, and then re-open the bug after the package migrated)
+ 
  ⚠️ Only land this in the release/updates pocket after PPAs have been
  resigned
  
  (This bumps the apt version to 2.8.0. APT uses the odd/even number
  system, with 2.7.x being the development series for 2.8, and this is the
  only change left for the 2.8 release, save for some minor
  translation/test suite improvements)
  
  (Please also look at bug 2073126 for the follow-up changes to mitigate
  regression potential).
  
  [Impact]
  APT is currently just warning about keys that it should be rejecting to give Launchpad time to resign PPAs. This needs to be bumped to an error such that the crypto policy is fully implemented and we only trust keys that are still being trusted. #2055193
  
  A warning provides some help right now to third-parties to fix their
  repositories, but it's not *safe*: A repository could have multiple
  signing keys and be signed by a good key now, then later, a previous key
  still in trusted.gpg.d could be revoked and we'd degrade to warnings,
  which, given that we update in the background automatically, the user
  may not see.
  
  Other fixes:
  - The test suite has been made less flaky in two places
  - Documentation translation has been unfuzzied for URL changes in 2.7.14
  
  [Test plan]
  The vast regression test suite prevents regression in other components.
  
  Test Case A: Existing noble system (warning)
  
  0. Update an existing noble container to the new APT
  1. Observe/etc/apt/apt.conf.d/00-temporary-rsa1024 being created
  2. Add a PPA with an old 1024-bit signing key
  3. Run apt update
  4. Observe that the PPA is updated with a warning
  
  Test Case B: New noble system (error)
  
  0. Bootstrap a new noble system including apt from proposed (using e.g. mmdebstrap)
  1. Observe NO /etc/apt/apt.conf.d/00-temporary-rsa1024
  2. Add a PPA with an old 1024-bit signing key
  3. Run apt update
  4. Observe that the PPA is not updated, but the other repositories are
  
  Test Case C: mantic -> noble (error)
  
  0. Upgrade mantic to noble w/ apt from proposed, observe behavior as in
  B
  
  Test Case D: jammy -> noble (error)
  
  0. Upgrade jammy to noble w/ apt from proposed, observe behavior as in B
  
  [Where problems could occur]
  apt will start to fail updates of repositories with weak signing keys, but it will have warned users about that before. Given that it is still early in the cycle, and we only enable updates from 22.04.1 for 24.04.1, this seems the right tradeoff for future security.

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https://bugs.launchpad.net/bugs/2060721

Title:
  APT 2.8.4+: Promote weak key warnings to errors

Status in apt package in Ubuntu:
  Fix Released
Status in apt source package in Noble:
  Fix Committed

Bug description:
  (2.8.3 update references this bug as previous uploads tried to fix it
  and have not been fully reverted, per discussion with rbasak we agreed
  to just ignore this bug for SRU verification; as in mark it
  verification-done, and then re-open the bug after the package
  migrated)

  ⚠️ Only land this in the release/updates pocket after PPAs have been
  resigned

  (This bumps the apt version to 2.8.0. APT uses the odd/even number
  system, with 2.7.x being the development series for 2.8, and this is
  the only change left for the 2.8 release, save for some minor
  translation/test suite improvements)

  (Please also look at bug 2073126 for the follow-up changes to mitigate
  regression potential).

  [Impact]
  APT is currently just warning about keys that it should be rejecting to give Launchpad time to resign PPAs. This needs to be bumped to an error such that the crypto policy is fully implemented and we only trust keys that are still being trusted. #2055193

  A warning provides some help right now to third-parties to fix their
  repositories, but it's not *safe*: A repository could have multiple
  signing keys and be signed by a good key now, then later, a previous
  key still in trusted.gpg.d could be revoked and we'd degrade to
  warnings, which, given that we update in the background automatically,
  the user may not see.

  Other fixes:
  - The test suite has been made less flaky in two places
  - Documentation translation has been unfuzzied for URL changes in 2.7.14

  [Test plan]
  The vast regression test suite prevents regression in other components.

  Test Case A: Existing noble system (warning)

  0. Update an existing noble container to the new APT
  1. Observe/etc/apt/apt.conf.d/00-temporary-rsa1024 being created
  2. Add a PPA with an old 1024-bit signing key
  3. Run apt update
  4. Observe that the PPA is updated with a warning

  Test Case B: New noble system (error)

  0. Bootstrap a new noble system including apt from proposed (using e.g. mmdebstrap)
  1. Observe NO /etc/apt/apt.conf.d/00-temporary-rsa1024
  2. Add a PPA with an old 1024-bit signing key
  3. Run apt update
  4. Observe that the PPA is not updated, but the other repositories are

  Test Case C: mantic -> noble (error)

  0. Upgrade mantic to noble w/ apt from proposed, observe behavior as
  in B

  Test Case D: jammy -> noble (error)

  0. Upgrade jammy to noble w/ apt from proposed, observe behavior as in
  B

  [Where problems could occur]
  apt will start to fail updates of repositories with weak signing keys, but it will have warned users about that before. Given that it is still early in the cycle, and we only enable updates from 22.04.1 for 24.04.1, this seems the right tradeoff for future security.

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