1 files changed, 191 insertions, 0 deletions
diff --git a/drm/libdrmframework/plugins/forward-lock/internal-format/common/FwdLockGlue.c b/drm/libdrmframework/plugins/forward-lock/internal-format/common/FwdLockGlue.c
new file mode 100644
index 0000000..92bda8f
--- /dev/null
+++ b/drm/libdrmframework/plugins/forward-lock/internal-format/common/FwdLockGlue.c
@@ -0,0 +1,191 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <openssl/aes.h>
+
+#include "FwdLockGlue.h"
+
+#define TRUE 1
+#define FALSE 0
+
+#define KEY_SIZE 16
+#define KEY_SIZE_IN_BITS (KEY_SIZE * 8)
+
+static int isInitialized = FALSE;
+
+static const char strKeyFilename[] = "/data/drm/fwdlock/kek.dat";
+
+static AES_KEY encryptionRoundKeys;
+static AES_KEY decryptionRoundKeys;
+
+/**
+ * Creates all directories along the fully qualified path of the given file.
+ *
+ * @param[in] path A reference to the fully qualified path of a file.
+ * @param[in] mode The access mode to use for the directories being created.
+ *
+ * @return A Boolean value indicating whether the operation was successful.
+ */
+static int FwdLockGlue_CreateDirectories(const char *path, mode_t mode) {
+    int result = TRUE;
+    size_t partialPathLength = strlen(path);
+    char *partialPath = malloc(partialPathLength + 1);
+    if (partialPath == NULL) {
+        result = FALSE;
+    } else {
+        size_t i;
+        for (i = 0; i < partialPathLength; ++i) {
+            if (path[i] == '/' && i > 0) {
+                partialPath[i] = '\0';
+                if (mkdir(partialPath, mode) != 0 && errno != EEXIST) {
+                    result = FALSE;
+                    break;
+                }
+            }
+            partialPath[i] = path[i];
+        }
+        free(partialPath);
+    }
+    return result;
+}
+
+/**
+ * Initializes the round keys used for encryption and decryption of session keys. First creates a
+ * device-unique key-encryption key if none exists yet.
+ */
+static void FwdLockGlue_InitializeRoundKeys() {
+    unsigned char keyEncryptionKey[KEY_SIZE];
+    int fileDesc = open(strKeyFilename, O_RDONLY);
+    if (fileDesc >= 0) {
+        if (read(fileDesc, keyEncryptionKey, KEY_SIZE) == KEY_SIZE) {
+            isInitialized = TRUE;
+        }
+        (void)close(fileDesc);
+    } else if (errno == ENOENT &&
+               FwdLockGlue_GetRandomNumber(keyEncryptionKey, KEY_SIZE) &&
+               FwdLockGlue_CreateDirectories(strKeyFilename, S_IRWXU)) {
+        fileDesc = open(strKeyFilename, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR);
+        if (fileDesc >= 0) {
+            if (write(fileDesc, keyEncryptionKey, KEY_SIZE) == KEY_SIZE) {
+                isInitialized = TRUE;
+            }
+            (void)close(fileDesc);
+        }
+    }
+    if (isInitialized) {
+        if (AES_set_encrypt_key(keyEncryptionKey, KEY_SIZE_IN_BITS, &encryptionRoundKeys) != 0 ||
+            AES_set_decrypt_key(keyEncryptionKey, KEY_SIZE_IN_BITS, &decryptionRoundKeys) != 0) {
+            isInitialized = FALSE;
+        }
+    }
+    memset(keyEncryptionKey, 0, KEY_SIZE); // Zero out key data.
+}
+
+/**
+ * Validates the padding of a decrypted key.
+ *
+ * @param[in] pData A reference to the buffer containing the decrypted key and padding.
+ * @param[in] decryptedKeyLength The length in bytes of the decrypted key.
+ *
+ * @return A Boolean value indicating whether the padding was valid.
+ */
+static int FwdLockGlue_ValidatePadding(const unsigned char *pData, size_t decryptedKeyLength) {
+    size_t i;
+    size_t padding = AES_BLOCK_SIZE - (decryptedKeyLength % AES_BLOCK_SIZE);
+    pData += decryptedKeyLength;
+    for (i = 0; i < padding; ++i) {
+        if ((size_t)*pData != padding) {
+            return FALSE;
+        }
+        ++pData;
+    }
+    return TRUE;
+}
+
+int FwdLockGlue_GetRandomNumber(void *pBuffer, size_t numBytes) {
+    // Generate 'cryptographically secure' random bytes by reading them from "/dev/urandom" (the
+    // non-blocking version of "/dev/random").
+    ssize_t numBytesRead = 0;
+    int fileDesc = open("/dev/urandom", O_RDONLY);
+    if (fileDesc >= 0) {
+        numBytesRead = read(fileDesc, pBuffer, numBytes);
+        (void)close(fileDesc);
+    }
+    return numBytesRead >= 0 && (size_t)numBytesRead == numBytes;
+}
+
+int FwdLockGlue_InitializeKeyEncryption() {
+    static pthread_once_t once = PTHREAD_ONCE_INIT;
+    pthread_once(&once, FwdLockGlue_InitializeRoundKeys);
+    return isInitialized;
+}
+
+size_t FwdLockGlue_GetEncryptedKeyLength(size_t plaintextKeyLength) {
+    return ((plaintextKeyLength / AES_BLOCK_SIZE) + 2) * AES_BLOCK_SIZE;
+}
+
+int FwdLockGlue_EncryptKey(const void *pPlaintextKey,
+                           size_t plaintextKeyLength,
+                           void *pEncryptedKey,
+                           size_t encryptedKeyLength) {
+    int result = FALSE;
+    assert(encryptedKeyLength == FwdLockGlue_GetEncryptedKeyLength(plaintextKeyLength));
+    if (FwdLockGlue_InitializeKeyEncryption()) {
+        unsigned char initVector[AES_BLOCK_SIZE];
+        if (FwdLockGlue_GetRandomNumber(initVector, AES_BLOCK_SIZE)) {
+            size_t padding = AES_BLOCK_SIZE - (plaintextKeyLength % AES_BLOCK_SIZE);
+            size_t dataLength = encryptedKeyLength - AES_BLOCK_SIZE;
+            memcpy(pEncryptedKey, pPlaintextKey, plaintextKeyLength);
+            memset((unsigned char *)pEncryptedKey + plaintextKeyLength, (int)padding, padding);
+            memcpy((unsigned char *)pEncryptedKey + dataLength, initVector, AES_BLOCK_SIZE);
+            AES_cbc_encrypt(pEncryptedKey, pEncryptedKey, dataLength, &encryptionRoundKeys,
+                            initVector, AES_ENCRYPT);
+            result = TRUE;
+        }
+    }
+    return result;
+}
+
+int FwdLockGlue_DecryptKey(const void *pEncryptedKey,
+                           size_t encryptedKeyLength,
+                           void *pDecryptedKey,
+                           size_t decryptedKeyLength) {
+    int result = FALSE;
+    assert(encryptedKeyLength == FwdLockGlue_GetEncryptedKeyLength(decryptedKeyLength));
+    if (FwdLockGlue_InitializeKeyEncryption()) {
+        size_t dataLength = encryptedKeyLength - AES_BLOCK_SIZE;
+        unsigned char *pData = malloc(dataLength);
+        if (pData != NULL) {
+            unsigned char initVector[AES_BLOCK_SIZE];
+            memcpy(pData, pEncryptedKey, dataLength);
+            memcpy(initVector, (const unsigned char *)pEncryptedKey + dataLength, AES_BLOCK_SIZE);
+            AES_cbc_encrypt(pData, pData, dataLength, &decryptionRoundKeys, initVector,
+                            AES_DECRYPT);
+            memcpy(pDecryptedKey, pData, decryptedKeyLength);
+            result = FwdLockGlue_ValidatePadding(pData, decryptedKeyLength);
+            free(pData);
+        }
+    }
+    return result;
+}