commit ca9ca43825308a956aa29f45957c5ce07535d1f8
author Quallenauge <Hamsi2k@freenet.de> Thu Feb 17 20:56:58 2022 +0100
committer bigbiff <bigbiff@teamw.in> Sat May 14 16:33:56 2022 +0000
tree 7f99dfb4bdbb5d04e4fedc66cb33823f3fdae7fd
parent 4b7637e3238dc1abe73235611c04909c13d73f95

Add support of A12 keymaster_key_blob files structure for legacy km

In A12 keymaster_key_blob format changed
Compared to A11 it contains another new 8 bytes at beginning "pKMblob\0" (in hex 0x704B4D626C6F6200)
We can just ignore them.

Add support for keymaster0 / keymaster1 too.

Change-Id: I6982879248ab805c7b6d8820d5b67c772f530ee4

crypto/fde/cryptfs.cpp

diff --git a/crypto/fde/cryptfs.cpp b/crypto/fde/cryptfs.cpp
index 60912fb..70e7a57 100644
--- a/crypto/fde/cryptfs.cpp
+++ b/crypto/fde/cryptfs.cpp
@@ -114,6 +114,7 @@
 static_assert(INTERMEDIATE_BUF_SIZE == SCRYPT_LEN,
               "Mismatch of intermediate key sizes");
 
+static const std::string kPkmBlob("pKMblob\x00", 8);
 #define KEY_IN_FOOTER  "footer"
 
 #define DEFAULT_HEX_PASSWORD "64656661756c745f70617373776f7264"
@@ -469,6 +470,14 @@
 
     int rc = -1;
 
+    // In A12 keymaster_key_blob format changed:
+    // it have useless for us bytes in beginning, so remove them to correctly handle key
+    std::string kmKey( &ftr->keymaster_blob[0], &ftr->keymaster_blob[0]+ftr->keymaster_blob_size );
+    if (!kmKey.compare(0, kPkmBlob.size(), kPkmBlob)) {
+        kmKey.erase(0, kPkmBlob.size());
+    }
+    keymaster_key_blob_t key = { reinterpret_cast<const uint8_t*>(kmKey.c_str()), kmKey.size() };
+
 #if TW_KEYMASTER_MAX_API >= 1
     keymaster0_device_t *keymaster0_dev = 0;
     keymaster1_device_t *keymaster1_dev = 0;
@@ -492,8 +501,8 @@
 
         rc = keymaster0_dev->sign_data(keymaster0_dev,
                                       &params,
-                                      ftr->keymaster_blob,
-                                      ftr->keymaster_blob_size,
+                                      key.key_material,
+                                      key.key_material_size,
                                       to_sign,
                                       to_sign_size,
                                       signature,
@@ -502,7 +511,6 @@
     }
 #if TW_KEYMASTER_MAX_API >= 1
     else if (keymaster1_dev) {
-        keymaster_key_blob_t key = { ftr->keymaster_blob, ftr->keymaster_blob_size };
         keymaster_key_param_t params[] = {
             keymaster_param_enum(KM_TAG_PADDING, KM_PAD_NONE),
             keymaster_param_enum(KM_TAG_DIGEST, KM_DIGEST_NONE),
@@ -559,7 +567,6 @@
     }
 #if TW_KEYMASTER_MAX_API > 1
     else if (keymaster2_dev) {
-        keymaster_key_blob_t key = { ftr->keymaster_blob, ftr->keymaster_blob_size };
         keymaster_key_param_t params[] = {
             keymaster_param_enum(KM_TAG_PADDING, KM_PAD_NONE),
             keymaster_param_enum(KM_TAG_DIGEST, KM_DIGEST_NONE),