Consistently use constant-time comparison of password hashes instead of bare password strings #7455
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As per golang/go#47001 even subtle.ConstantTimeCompare should never be used with variable-length inputs, as it will return 0 if the lengths do not match. Switch to consistently using constant-time comparisons of hashes for password checks to avoid any possible side-channel leaks that could be combined with other vectors to discover password lengths. Signed-off-by: Brad Davidson <[email protected]>
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brandond
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May 8, 2023
| @@ -60,14 +60,6 @@ func Read(file string) (*Passwd, error) { | |||
| return result, nil | |||
| } | |||
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| func (p *Passwd) Check(name, pass string) (matches bool, exists bool) { | |||
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Note: this function was not used anywhere in the codebase.
Codecov ReportPatch coverage:
Additional details and impacted files@@ Coverage Diff @@
## master #7455 +/- ##
===========================================
+ Coverage 19.48% 47.53% +28.04%
===========================================
Files 81 139 +58
Lines 5497 14254 +8757
===========================================
+ Hits 1071 6775 +5704
- Misses 4204 6403 +2199
- Partials 222 1076 +854
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briandowns
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May 9, 2023
johnatasr
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May 9, 2023
rbrtbnfgl
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May 9, 2023
This was referenced May 10, 2023
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Proposed Changes
Consistently use constant-time comparison of password hashes
As per golang/go#47001 even subtle.ConstantTimeCompare should never be used with variable-length inputs, as it will return 0 if the lengths do not match. Switch to consistently using constant-time comparisons of hashes for password checks to avoid any possible side-channel leaks that could be combined with other vectors to discover password lengths.
The
passwordfilemisuse ofsubtle.ConstantTimeComparecomes from upstream Kubernetes:https://github.com/kubernetes/kubernetes/blob/release-1.18/staging/src/k8s.io/apiserver/plugin/pkg/authenticator/password/passwordfile/passwordfile.go
Types of Changes
bugfix
Verification
Normal CI and release testing (no visible user impact)
Testing
Linked Issues
User-Facing Change
Further Comments