Cope with Keymaster->KeyMint device upgrade
When handling keyblob upgrade required, also watch out for an invalid
keyblob error that might indicate that a key used to be a
km_compat-wrapped Keymaster key.
In this situation, try stripping off the km_compat prefix and
attempt upgrade of the inner keyblob data instead.
Bug: 251426862
Bug: 283077822
Bug: 296403357
Test: tested with ARC upgrade, see b/296403357
Change-Id: I8539455e33ab2e1c97f26174476ee9d616269e74
diff --git a/keystore2/src/km_compat.rs b/keystore2/src/km_compat.rs
index 035edd9..8eba02d 100644
--- a/keystore2/src/km_compat.rs
+++ b/keystore2/src/km_compat.rs
@@ -32,6 +32,11 @@
use anyhow::Context;
use keystore2_crypto::{hmac_sha256, HMAC_SHA256_LEN};
+/// Magic prefix used by the km_compat C++ code to mark a key that is owned by an
+/// underlying Keymaster hardware device that has been wrapped by km_compat. (The
+/// final zero byte indicates that the blob is not software emulated.)
+pub const KEYMASTER_BLOB_HW_PREFIX: &[u8] = b"pKMblob\x00";
+
/// Key data associated with key generation/import.
#[derive(Debug, PartialEq, Eq)]
pub enum KeyImportData<'a> {