fix: use secure file permissions for config files

[Itx-Psycho0]

Summary

Fixes config file permissions from 0777 to 0600 for security.

Changes

• Config files now use 0600 (owner read/write only)
• Config directories use 0755 (standard directory permissions)
• Added tests to verify correct permissions

Security Impact

• Prevents unauthorized users from reading sensitive config data
• Prevents unauthorized modification of configuration
• Follows industry standard (kubectl, docker, git use 0600)

Testing

• Added TestWrite_FilePermissions and TestCreatePaths_DirectoryPermissions
• All existing tests pass
• make check passes

Fixes #3725

[knative-prow]

Hi @Itx-Psycho0. Thanks for your PR.

I'm waiting for a knative member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[matejvasek]

PTAL @lkingland

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.96%. Comparing base (0209813) to head (5aa2383).
⚠️ Report is 24 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3726      +/-   ##
==========================================
+ Coverage   56.90%   56.96%   +0.06%     
==========================================
  Files         181      181              
  Lines       20933    21116     +183     
==========================================
+ Hits        11912    12029     +117     
- Misses       7811     7863      +52     
- Partials     1210     1224      +14     

Flag	Coverage Δ
e2e	35.80% <0.00%> (-0.36%)	⬇️
e2e go	32.42% <0.00%> (-0.33%)	⬇️
e2e node	28.20% <0.00%> (-0.29%)	⬇️
e2e python	32.78% <0.00%> (-0.34%)	⬇️
e2e quarkus	28.34% <0.00%> (-0.29%)	⬇️
e2e rust	27.75% <0.00%> (-0.27%)	⬇️
e2e springboot	26.26% <0.00%> (-0.25%)	⬇️
e2e typescript	28.31% <0.00%> (-0.30%)	⬇️
e2e-config-ci	17.70% <0.00%> (-0.18%)	⬇️
integration	17.29% <0.00%> (-0.15%)	⬇️
unit macos-14	45.05% <100.00%> (+0.05%)	⬆️
unit macos-latest	45.05% <100.00%> (+0.05%)	⬆️
unit ubuntu-24.04-arm	45.32% <100.00%> (+0.15%)	⬆️
unit ubuntu-latest	46.00% <100.00%> (+0.16%)	⬆️
unit windows-latest	45.09% <100.00%> (+0.12%)	⬆️

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[gauron99]

FYI I found https://specifications.freedesktop.org/basedir/latest/ which states

If, when attempting to write a file, the destination directory is non-existent an attempt should be made to create it with permission 0700. If the destination directory exists already the permissions should not be changed.

so maybe we could go even more strict 😄
cc @matejvasek

[matejvasek]

/approve
/lgtm

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Itx-Psycho0, matejvasek

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