commit 9e7d723f43ae7eaff849ccc56f8bacc1e84367ad
author Shawn Willden <swillden@google.com> Wed Jul 01 12:58:08 2015 -0600
committer Shawn Willden <swillden@google.com> Thu Jul 09 11:05:31 2015 -0600
tree 794dfa83b8d56b29911fe1df1ece0612a90cd50e
parent b5422432bf84c3bde1314a569f6f06b190602853

Allow any padding mode to be used with keys with KM_PAD_NONE.

Cherry-picked from internal.

Bug: 22229156
Change-Id: I5de66c3ed86244452e7776bff9523e35030713e9

aes_operation.cpp

diff --git a/aes_operation.cpp b/aes_operation.cpp
index 2325ad4..face408 100644
--- a/aes_operation.cpp
+++ b/aes_operation.cpp
@@ -37,6 +37,19 @@
 static const size_t GCM_MAX_TAG_LENGTH = 16;
 static const size_t GCM_MIN_TAG_LENGTH = 12;
 
+inline bool allows_padding(keymaster_block_mode_t block_mode) {
+    switch (block_mode) {
+    case KM_MODE_CTR:
+    case KM_MODE_GCM:
+        return false;
+    case KM_MODE_ECB:
+    case KM_MODE_CBC:
+        return true;
+    }
+    assert(false /* Can't get here */);
+    return false;
+}
+
 Operation* AesOperationFactory::CreateOperation(const Key& key,
                                                 const AuthorizationSet& begin_params,
                                                 keymaster_error_t* error) {
@@ -77,17 +90,10 @@
     }
 
     keymaster_padding_t padding;
-    if (!begin_params.GetTagValue(TAG_PADDING, &padding)) {
-        LOG_E("%d padding modes specified in begin params", begin_params.GetTagCount(TAG_PADDING));
-        *error = KM_ERROR_UNSUPPORTED_PADDING_MODE;
-    } else if (!supported(padding)) {
-        LOG_E("Padding mode %d not supported", padding);
-        *error = KM_ERROR_UNSUPPORTED_PADDING_MODE;
-    } else if (block_mode == KM_MODE_CTR && padding != KM_PAD_NONE) {
-        LOG_E("CTR mode does not support padding", 0);
-        *error = KM_ERROR_INCOMPATIBLE_PADDING_MODE;
-    } else if (!key.authorizations().Contains(TAG_PADDING, padding)) {
-        LOG_E("Padding mode %d was specified, but not authorized by key", padding);
+    if (!GetAndValidatePadding(begin_params, key, &padding, error))
+        return nullptr;
+    if (!allows_padding(block_mode) && padding != KM_PAD_NONE) {
+        LOG_E("Mode does not support padding", 0);
         *error = KM_ERROR_INCOMPATIBLE_PADDING_MODE;
     }
 

android_keymaster_test.cpp

diff --git a/android_keymaster_test.cpp b/android_keymaster_test.cpp
index 49cff6e..341183b 100644
--- a/android_keymaster_test.cpp
+++ b/android_keymaster_test.cpp
@@ -2115,6 +2115,24 @@
     EXPECT_EQ(0, GetParam()->keymaster0_calls());
 }
 
+TEST_P(EncryptionOperationsTest, AesEcbNoPaddingKeyWithPkcs7Padding) {
+    ASSERT_EQ(KM_ERROR_OK, GenerateKey(AuthorizationSetBuilder()
+                                           .AesEncryptionKey(128)
+                                           .Authorization(TAG_BLOCK_MODE, KM_MODE_ECB)
+                                           .Authorization(TAG_PADDING, KM_PAD_NONE)));
+
+    // Try various message lengths; all should work.
+    for (size_t i = 0; i < 32; ++i) {
+        string message(i, 'a');
+        string ciphertext = EncryptMessage(message, KM_MODE_ECB, KM_PAD_PKCS7);
+        EXPECT_EQ(i + 16 - (i % 16), ciphertext.size());
+        string plaintext = DecryptMessage(ciphertext, KM_MODE_ECB, KM_PAD_PKCS7);
+        EXPECT_EQ(message, plaintext);
+    }
+
+    EXPECT_EQ(0, GetParam()->keymaster0_calls());
+}
+
 TEST_P(EncryptionOperationsTest, AesEcbPkcs7PaddingCorrupted) {
     ASSERT_EQ(KM_ERROR_OK, GenerateKey(AuthorizationSetBuilder()
                                            .AesEncryptionKey(128)