You have been subscribed to a public bug by Simon Poirier (simpoir):
[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
** Affects: landscape-client
Importance: High
Assignee: Simon Poirier (simpoir)
Status: Fix Committed
** Affects: landscape-client (Ubuntu)
Importance: Undecided
Assignee: Simon Poirier (simpoir)
Status: In Progress
** Affects: landscape-client (Ubuntu Bionic)
Importance: Undecided
Assignee: Simon Poirier (simpoir)
Status: In Progress
** Affects: landscape-client (Ubuntu Focal)
Importance: Undecided
Assignee: Simon Poirier (simpoir)
Status: In Progress
** Affects: landscape-client (Ubuntu Groovy)
Importance: Undecided
Assignee: Simon Poirier (simpoir)
Status: Won't Fix
** Affects: landscape-client (Ubuntu Hirsute)
Importance: Undecided
Assignee: Simon Poirier (simpoir)
Status: In Progress
** Affects: landscape-client (Ubuntu Impish)
Importance: Undecided
Status: New
** Affects: landscape-client (Ubuntu Jammy)
Importance: Undecided
Assignee: Simon Poirier (simpoir)
Status: In Progress
--
Changed ubuntu-keyring paths breaks upgrade to focal.
https://bugs.launchpad.net/bugs/1903776
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