credstore: Fix several problems with credstore.
The root of the problem is that in some cases credstore would
pass auth- and verification-tokens to the Identity Credential
HAL without first having obtained a challenge via
IIdentityCredential.createAuthChallenge(). This makes it
impossible for the TA to validate the verification token for
freshness.
This is easily fixed by simply ensuring createAuthChallenge()
is called (and the returned challenge is used in the requested
verification token) whenever dealing with ACPs using user
authentication.
Additional issues / changes:
- During Android 12 development, an use-after-free bug was
introduced in Credential.cpp L120.
- keystore's getTokensForCredstore() had some bugs in how to
select an auth-token, in particular mixing authTokenAgeMillis
(milliseconds) with time_t values (seconds)
- as a result, keystore would sometimes return tokens older
than what credstore requested. This wasn't actually problem
because the TA would check it anyway.
- we now precisely define semantics in IKeystoreService.aidl
- Another potential use-after-free bug was found in
Credential.cpp L767
None of the fixes for these bugs affect CTS or VTS tests.
Bug: 181893400
Test: atest android.security.identity.cts on emulator
Test: atest android.security.identity.cts on crosshatch (w/ Android 11 era HAL)
Test: CtsVerifier's Identity Credential Authentication test crosshatch (w/ Android 11 era HAL)
Change-Id: I45a3fd16eff3b6a232d8b8c88f2e3dd3619a9c03
8 files changed