login: T5875: fix corner case for KeyError: 'getpwuid(): uid not found: XXXX' (backport #3270)

[mergify]

Change Summary

Commit 1b36442 ("login: T5875: restore home directory permissions only when needed") added logic to chown the users home directory if it's UID changes. This might happen when a user account is deleted and re-added to the system.

Under rar e circumstances it was possible that the implementation triggered

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 'getpwuid(): uid not found: XXXX'

This has been fixed by re-arranging the code path with an additional try/except if the PW database information could not be retrieved leading to an implicit chown() of the home directory to the user beeing added.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5875

Related PR(s)

• login: T5875: restore home directory permissions only when needed #2726

Component(s) name

login

Proposed changes

How to test

Smoketest result

[email protected]:~$ /usr/libexec/vyos/tests/smoke/cli/test_system_login.py
test_add_linux_system_user (__main__.TestSystemLogin.test_add_linux_system_user) ... ok
test_radius_kernel_features (__main__.TestSystemLogin.test_radius_kernel_features) ... ok
test_system_login_max_login_session (__main__.TestSystemLogin.test_system_login_max_login_session) ... ok
test_system_login_otp (__main__.TestSystemLogin.test_system_login_otp) ... ok
test_system_login_radius_ipv4 (__main__.TestSystemLogin.test_system_login_radius_ipv4) ... ok
test_system_login_radius_ipv6 (__main__.TestSystemLogin.test_system_login_radius_ipv6) ... ok
test_system_login_tacacs (__main__.TestSystemLogin.test_system_login_tacacs) ... ok
test_system_login_user (__main__.TestSystemLogin.test_system_login_user) ... ok
test_system_user_ssh_key (__main__.TestSystemLogin.test_system_user_ssh_key) ... ok

----------------------------------------------------------------------
Ran 9 tests in 233.063s

OK

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

---

This is an automatic backport of pull request #3270 done by [Mergify](https://mergify.com).