C++ AIDL on-device GateKeeper / SharedSecret impl
Because Keystore2 always requires valid auth tokens for user keys, this
copies and extends the existing in-guest GateKeeper implementation to
negotiate a shared secret key with Keymint in order to generate a
session key for signing auth tokens.
This implementation also uses AIDL rather than HIDL to interact with the
framework. It's also packaged in an APEX.
The files are cobbled together from a few sources:
- SoftGateKeeper.h is based on hardware/interfaces/gatekeeper/1.0/software/SoftGateKeeper.h
- GateKeeper.{cpp,h} are based on device/google/cuttlefish/guest/hals/gatekeeper/remote/remote_gatekeeper.{cpp,h}
- SharedSecret.{cpp,h} are based on device/google/cuttlefish/guest/hals/keymint/remote/remote_shared_secret.{cpp,h}
- Apex files are based on device/google/cuttlefish/guest/hals/keymint/rust/
Keymint modifications to use BOOT_TIME are lifted from
https://android-review.git.corp.google.com/c/platform/hardware/interfaces/+/2856649/6..8/security/keymint/aidl/default/ta/clock.rs#38
Bug: 332376454
Change-Id: I81845d5e6370bdddb1a24d67437964e03a5fb243
Test: Run with rust-nonsecure keymint on Cuttlefish
diff --git a/security/keymint/aidl/default/ta/clock.rs b/security/keymint/aidl/default/ta/clock.rs
index ad8509a..03e04ec 100644
--- a/security/keymint/aidl/default/ta/clock.rs
+++ b/security/keymint/aidl/default/ta/clock.rs
@@ -16,25 +16,29 @@
//! Monotonic clock implementation.
use kmr_common::crypto;
-use std::time::Instant;
/// Monotonic clock.
-pub struct StdClock {
- start: Instant,
-}
+pub struct StdClock;
impl StdClock {
/// Create new clock instance, holding time since construction.
pub fn new() -> Self {
- Self {
- start: Instant::now(),
- }
+ Self {}
}
}
impl crypto::MonotonicClock for StdClock {
fn now(&self) -> crypto::MillisecondsSinceEpoch {
- let duration = self.start.elapsed();
- crypto::MillisecondsSinceEpoch(duration.as_millis().try_into().unwrap())
+ let mut time = libc::timespec { tv_sec: 0, tv_nsec: 0 };
+ // Use `CLOCK_BOOTTIME` for consistency with the times used by the Cuttlefish
+ // C++ implementation of Gatekeeper.
+ let rc =
+ // Safety: `time` is a valid structure.
+ unsafe { libc::clock_gettime(libc::CLOCK_BOOTTIME, &mut time as *mut libc::timespec) };
+ if rc < 0 {
+ log::warn!("failed to get time!");
+ return crypto::MillisecondsSinceEpoch(0);
+ }
+ crypto::MillisecondsSinceEpoch(((time.tv_sec * 1000) + (time.tv_nsec / 1000 / 1000)).into())
}
}