1 files changed, 454 insertions, 0 deletions
diff --git a/drm/libdrmframework/plugins/forward-lock/internal-format/decoder/FwdLockFile.c b/drm/libdrmframework/plugins/forward-lock/internal-format/decoder/FwdLockFile.c
new file mode 100644
index 0000000..365bdec
--- /dev/null
+++ b/drm/libdrmframework/plugins/forward-lock/internal-format/decoder/FwdLockFile.c
@@ -0,0 +1,454 @@
+/*
+ * 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 <utils/Log.h>
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <openssl/aes.h>
+#include <openssl/hmac.h>
+
+#include "FwdLockFile.h"
+#include "FwdLockGlue.h"
+
+#define TRUE 1
+#define FALSE 0
+
+#define INVALID_OFFSET ((off64_t)-1)
+
+#define INVALID_BLOCK_INDEX ((uint64_t)-1)
+
+#define MAX_NUM_SESSIONS 128
+
+#define KEY_SIZE AES_BLOCK_SIZE
+#define KEY_SIZE_IN_BITS (KEY_SIZE * 8)
+
+#define SHA1_HASH_SIZE 20
+#define SHA1_BLOCK_SIZE 64
+
+#define FWD_LOCK_VERSION 0
+#define FWD_LOCK_SUBFORMAT 0
+#define USAGE_RESTRICTION_FLAGS 0
+#define CONTENT_TYPE_LENGTH_POS 7
+#define TOP_HEADER_SIZE 8
+
+#define SIG_CALC_BUFFER_SIZE (16 * SHA1_BLOCK_SIZE)
+
+/**
+ * Data type for the per-file state information needed by the decoder.
+ */
+typedef struct FwdLockFile_Session {
+    int fileDesc;
+    unsigned char topHeader[TOP_HEADER_SIZE];
+    char *pContentType;
+    size_t contentTypeLength;
+    void *pEncryptedSessionKey;
+    size_t encryptedSessionKeyLength;
+    unsigned char dataSignature[SHA1_HASH_SIZE];
+    unsigned char headerSignature[SHA1_HASH_SIZE];
+    off64_t dataOffset;
+    off64_t filePos;
+    AES_KEY encryptionRoundKeys;
+    HMAC_CTX signingContext;
+    unsigned char keyStream[AES_BLOCK_SIZE];
+    uint64_t blockIndex;
+} FwdLockFile_Session_t;
+
+static FwdLockFile_Session_t *sessionPtrs[MAX_NUM_SESSIONS] = { NULL };
+
+static pthread_mutex_t sessionAcquisitionMutex = PTHREAD_MUTEX_INITIALIZER;
+
+static const unsigned char topHeaderTemplate[] =
+    { 'F', 'W', 'L', 'K', FWD_LOCK_VERSION, FWD_LOCK_SUBFORMAT, USAGE_RESTRICTION_FLAGS };
+
+/**
+ * Acquires an unused file session for the given file descriptor.
+ *
+ * @param[in] fileDesc A file descriptor.
+ *
+ * @return A session ID.
+ */
+static int FwdLockFile_AcquireSession(int fileDesc) {
+    int sessionId = -1;
+    if (fileDesc < 0) {
+        errno = EBADF;
+    } else {
+        int i;
+        pthread_mutex_lock(&sessionAcquisitionMutex);
+        for (i = 0; i < MAX_NUM_SESSIONS; ++i) {
+            int candidateSessionId = (fileDesc + i) % MAX_NUM_SESSIONS;
+            if (sessionPtrs[candidateSessionId] == NULL) {
+                sessionPtrs[candidateSessionId] = malloc(sizeof **sessionPtrs);
+                if (sessionPtrs[candidateSessionId] != NULL) {
+                    sessionPtrs[candidateSessionId]->fileDesc = fileDesc;
+                    sessionPtrs[candidateSessionId]->pContentType = NULL;
+                    sessionPtrs[candidateSessionId]->pEncryptedSessionKey = NULL;
+                    sessionId = candidateSessionId;
+                }
+                break;
+            }
+        }
+        pthread_mutex_unlock(&sessionAcquisitionMutex);
+        if (i == MAX_NUM_SESSIONS) {
+            ALOGE("Too many sessions opened at the same time");
+            errno = ENFILE;
+        }
+    }
+    return sessionId;
+}
+
+/**
+ * Finds the file session associated with the given file descriptor.
+ *
+ * @param[in] fileDesc A file descriptor.
+ *
+ * @return A session ID.
+ */
+static int FwdLockFile_FindSession(int fileDesc) {
+    int sessionId = -1;
+    if (fileDesc < 0) {
+        errno = EBADF;
+    } else {
+        int i;
+        pthread_mutex_lock(&sessionAcquisitionMutex);
+        for (i = 0; i < MAX_NUM_SESSIONS; ++i) {
+            int candidateSessionId = (fileDesc + i) % MAX_NUM_SESSIONS;
+            if (sessionPtrs[candidateSessionId] != NULL &&
+                sessionPtrs[candidateSessionId]->fileDesc == fileDesc) {
+                sessionId = candidateSessionId;
+                break;
+            }
+        }
+        pthread_mutex_unlock(&sessionAcquisitionMutex);
+        if (i == MAX_NUM_SESSIONS) {
+            errno = EBADF;
+        }
+    }
+    return sessionId;
+}
+
+/**
+ * Releases a file session.
+ *
+ * @param[in] sessionID A session ID.
+ */
+static void FwdLockFile_ReleaseSession(int sessionId) {
+    pthread_mutex_lock(&sessionAcquisitionMutex);
+    assert(0 <= sessionId && sessionId < MAX_NUM_SESSIONS && sessionPtrs[sessionId] != NULL);
+    free(sessionPtrs[sessionId]->pContentType);
+    free(sessionPtrs[sessionId]->pEncryptedSessionKey);
+    memset(sessionPtrs[sessionId], 0, sizeof *sessionPtrs[sessionId]); // Zero out key data.
+    free(sessionPtrs[sessionId]);
+    sessionPtrs[sessionId] = NULL;
+    pthread_mutex_unlock(&sessionAcquisitionMutex);
+}
+
+/**
+ * Derives keys for encryption and signing from the encrypted session key.
+ *
+ * @param[in,out] pSession A reference to a file session.
+ *
+ * @return A Boolean value indicating whether key derivation was successful.
+ */
+static int FwdLockFile_DeriveKeys(FwdLockFile_Session_t * pSession) {
+    int result;
+    struct FwdLockFile_DeriveKeys_Data {
+        AES_KEY sessionRoundKeys;
+        unsigned char value[KEY_SIZE];
+        unsigned char key[KEY_SIZE];
+    } *pData = malloc(sizeof *pData);
+    if (pData == NULL) {
+        result = FALSE;
+    } else {
+        result = FwdLockGlue_DecryptKey(pSession->pEncryptedSessionKey,
+                                        pSession->encryptedSessionKeyLength, pData->key, KEY_SIZE);
+        if (result) {
+            if (AES_set_encrypt_key(pData->key, KEY_SIZE_IN_BITS, &pData->sessionRoundKeys) != 0) {
+                result = FALSE;
+            } else {
+                // Encrypt the 16-byte value {0, 0, ..., 0} to produce the encryption key.
+                memset(pData->value, 0, KEY_SIZE);
+                AES_encrypt(pData->value, pData->key, &pData->sessionRoundKeys);
+                if (AES_set_encrypt_key(pData->key, KEY_SIZE_IN_BITS,
+                                        &pSession->encryptionRoundKeys) != 0) {
+                    result = FALSE;
+                } else {
+                    // Encrypt the 16-byte value {1, 0, ..., 0} to produce the signing key.
+                    ++pData->value[0];
+                    AES_encrypt(pData->value, pData->key, &pData->sessionRoundKeys);
+                    HMAC_CTX_init(&pSession->signingContext);
+                    HMAC_Init_ex(&pSession->signingContext, pData->key, KEY_SIZE, EVP_sha1(), NULL);
+                }
+            }
+        }
+        if (!result) {
+            errno = ENOSYS;
+        }
+        memset(pData, 0, sizeof pData); // Zero out key data.
+        free(pData);
+    }
+    return result;
+}
+
+/**
+ * Calculates the counter, treated as a 16-byte little-endian number, used to generate the keystream
+ * for the given block.
+ *
+ * @param[in] pNonce A reference to the nonce.
+ * @param[in] blockIndex The index number of the block.
+ * @param[out] pCounter A reference to the counter.
+ */
+static void FwdLockFile_CalculateCounter(const unsigned char *pNonce,
+                                         uint64_t blockIndex,
+                                         unsigned char *pCounter) {
+    unsigned char carry = 0;
+    size_t i = 0;
+    for (; i < sizeof blockIndex; ++i) {
+        unsigned char part = pNonce[i] + (unsigned char)(blockIndex >> (i * CHAR_BIT));
+        pCounter[i] = part + carry;
+        carry = (part < pNonce[i] || pCounter[i] < part) ? 1 : 0;
+    }
+    for (; i < AES_BLOCK_SIZE; ++i) {
+        pCounter[i] = pNonce[i] + carry;
+        carry = (pCounter[i] < pNonce[i]) ? 1 : 0;
+    }
+}
+
+/**
+ * Decrypts the byte at the current file position using AES-128-CTR. In CTR (or "counter") mode,
+ * encryption and decryption are performed using the same algorithm.
+ *
+ * @param[in,out] pSession A reference to a file session.
+ * @param[in] pByte The byte to decrypt.
+ */
+void FwdLockFile_DecryptByte(FwdLockFile_Session_t * pSession, unsigned char *pByte) {
+    uint64_t blockIndex = pSession->filePos / AES_BLOCK_SIZE;
+    uint64_t blockOffset = pSession->filePos % AES_BLOCK_SIZE;
+    if (blockIndex != pSession->blockIndex) {
+        // The first 16 bytes of the encrypted session key is used as the nonce.
+        unsigned char counter[AES_BLOCK_SIZE];
+        FwdLockFile_CalculateCounter(pSession->pEncryptedSessionKey, blockIndex, counter);
+        AES_encrypt(counter, pSession->keyStream, &pSession->encryptionRoundKeys);
+        pSession->blockIndex = blockIndex;
+    }
+    *pByte ^= pSession->keyStream[blockOffset];
+}
+
+int FwdLockFile_attach(int fileDesc) {
+    int sessionId = FwdLockFile_AcquireSession(fileDesc);
+    if (sessionId >= 0) {
+        FwdLockFile_Session_t *pSession = sessionPtrs[sessionId];
+        int isSuccess = FALSE;
+        if (read(fileDesc, pSession->topHeader, TOP_HEADER_SIZE) == TOP_HEADER_SIZE &&
+                memcmp(pSession->topHeader, topHeaderTemplate, sizeof topHeaderTemplate) == 0) {
+            pSession->contentTypeLength = pSession->topHeader[CONTENT_TYPE_LENGTH_POS];
+            assert(pSession->contentTypeLength <= UCHAR_MAX); // Untaint scalar for code checkers.
+            pSession->pContentType = malloc(pSession->contentTypeLength + 1);
+            if (pSession->pContentType != NULL &&
+                    read(fileDesc, pSession->pContentType, pSession->contentTypeLength) ==
+                            (ssize_t)pSession->contentTypeLength) {
+                pSession->pContentType[pSession->contentTypeLength] = '\0';
+                pSession->encryptedSessionKeyLength = FwdLockGlue_GetEncryptedKeyLength(KEY_SIZE);
+                pSession->pEncryptedSessionKey = malloc(pSession->encryptedSessionKeyLength);
+                if (pSession->pEncryptedSessionKey != NULL &&
+                        read(fileDesc, pSession->pEncryptedSessionKey,
+                             pSession->encryptedSessionKeyLength) ==
+                                (ssize_t)pSession->encryptedSessionKeyLength &&
+                        read(fileDesc, pSession->dataSignature, SHA1_HASH_SIZE) ==
+                                SHA1_HASH_SIZE &&
+                        read(fileDesc, pSession->headerSignature, SHA1_HASH_SIZE) ==
+                                SHA1_HASH_SIZE) {
+                    isSuccess = FwdLockFile_DeriveKeys(pSession);
+                }
+            }
+        }
+        if (isSuccess) {
+            pSession->dataOffset = pSession->contentTypeLength +
+                    pSession->encryptedSessionKeyLength + TOP_HEADER_SIZE + 2 * SHA1_HASH_SIZE;
+            pSession->filePos = 0;
+            pSession->blockIndex = INVALID_BLOCK_INDEX;
+        } else {
+            FwdLockFile_ReleaseSession(sessionId);
+            sessionId = -1;
+        }
+    }
+    return (sessionId >= 0) ? 0 : -1;
+}
+
+int FwdLockFile_open(const char *pFilename) {
+    int fileDesc = open(pFilename, O_RDONLY);
+    if (fileDesc < 0) {
+        ALOGE("failed to open file '%s': %s", pFilename, strerror(errno));
+        return fileDesc;
+    }
+
+    if (FwdLockFile_attach(fileDesc) < 0) {
+        (void)close(fileDesc);
+        fileDesc = -1;
+    }
+    return fileDesc;
+}
+
+ssize_t FwdLockFile_read(int fileDesc, void *pBuffer, size_t numBytes) {
+    ssize_t numBytesRead;
+    int sessionId = FwdLockFile_FindSession(fileDesc);
+    if (sessionId < 0) {
+        numBytesRead = -1;
+    } else {
+        FwdLockFile_Session_t *pSession = sessionPtrs[sessionId];
+        ssize_t i;
+        numBytesRead = read(pSession->fileDesc, pBuffer, numBytes);
+        for (i = 0; i < numBytesRead; ++i) {
+            FwdLockFile_DecryptByte(pSession, &((unsigned char *)pBuffer)[i]);
+            ++pSession->filePos;
+        }
+    }
+    return numBytesRead;
+}
+
+off64_t FwdLockFile_lseek(int fileDesc, off64_t offset, int whence) {
+    off64_t newFilePos;
+    int sessionId = FwdLockFile_FindSession(fileDesc);
+    if (sessionId < 0) {
+        newFilePos = INVALID_OFFSET;
+    } else {
+        FwdLockFile_Session_t *pSession = sessionPtrs[sessionId];
+        switch (whence) {
+        case SEEK_SET:
+            newFilePos = lseek64(pSession->fileDesc, pSession->dataOffset + offset, whence);
+            break;
+        case SEEK_CUR:
+        case SEEK_END:
+            newFilePos = lseek64(pSession->fileDesc, offset, whence);
+            break;
+        default:
+            errno = EINVAL;
+            newFilePos = INVALID_OFFSET;
+            break;
+        }
+        if (newFilePos != INVALID_OFFSET) {
+            if (newFilePos < pSession->dataOffset) {
+                // The new file position is illegal for an internal Forward Lock file. Restore the
+                // original file position.
+                (void)lseek64(pSession->fileDesc, pSession->dataOffset + pSession->filePos,
+                              SEEK_SET);
+                errno = EINVAL;
+                newFilePos = INVALID_OFFSET;
+            } else {
+                // The return value should be the file position that lseek64() would have returned
+                // for the embedded content file.
+                pSession->filePos = newFilePos - pSession->dataOffset;
+                newFilePos = pSession->filePos;
+            }
+        }
+    }
+    return newFilePos;
+}
+
+int FwdLockFile_detach(int fileDesc) {
+    int sessionId = FwdLockFile_FindSession(fileDesc);
+    if (sessionId < 0) {
+        return -1;
+    }
+    HMAC_CTX_cleanup(&sessionPtrs[sessionId]->signingContext);
+    FwdLockFile_ReleaseSession(sessionId);
+    return 0;
+}
+
+int FwdLockFile_close(int fileDesc) {
+    return (FwdLockFile_detach(fileDesc) == 0) ? close(fileDesc) : -1;
+}
+
+int FwdLockFile_CheckDataIntegrity(int fileDesc) {
+    int result;
+    int sessionId = FwdLockFile_FindSession(fileDesc);
+    if (sessionId < 0) {
+        result = FALSE;
+    } else {
+        struct FwdLockFile_CheckDataIntegrity_Data {
+            unsigned char signature[SHA1_HASH_SIZE];
+            unsigned char buffer[SIG_CALC_BUFFER_SIZE];
+        } *pData = malloc(sizeof *pData);
+        if (pData == NULL) {
+            result = FALSE;
+        } else {
+            FwdLockFile_Session_t *pSession = sessionPtrs[sessionId];
+            if (lseek64(pSession->fileDesc, pSession->dataOffset, SEEK_SET) !=
+                    pSession->dataOffset) {
+                result = FALSE;
+            } else {
+                ssize_t numBytesRead;
+                unsigned int signatureSize = SHA1_HASH_SIZE;
+                while ((numBytesRead =
+                        read(pSession->fileDesc, pData->buffer, SIG_CALC_BUFFER_SIZE)) > 0) {
+                    HMAC_Update(&pSession->signingContext, pData->buffer, (size_t)numBytesRead);
+                }
+                if (numBytesRead < 0) {
+                    result = FALSE;
+                } else {
+                    HMAC_Final(&pSession->signingContext, pData->signature, &signatureSize);
+                    assert(signatureSize == SHA1_HASH_SIZE);
+                    result = memcmp(pData->signature, pSession->dataSignature, SHA1_HASH_SIZE) == 0;
+                }
+                HMAC_Init_ex(&pSession->signingContext, NULL, KEY_SIZE, NULL, NULL);
+                (void)lseek64(pSession->fileDesc, pSession->dataOffset + pSession->filePos,
+                              SEEK_SET);
+            }
+            free(pData);
+        }
+    }
+    return result;
+}
+
+int FwdLockFile_CheckHeaderIntegrity(int fileDesc) {
+    int result;
+    int sessionId = FwdLockFile_FindSession(fileDesc);
+    if (sessionId < 0) {
+        result = FALSE;
+    } else {
+        FwdLockFile_Session_t *pSession = sessionPtrs[sessionId];
+        unsigned char signature[SHA1_HASH_SIZE];
+        unsigned int signatureSize = SHA1_HASH_SIZE;
+        HMAC_Update(&pSession->signingContext, pSession->topHeader, TOP_HEADER_SIZE);
+        HMAC_Update(&pSession->signingContext, (unsigned char *)pSession->pContentType,
+                    pSession->contentTypeLength);
+        HMAC_Update(&pSession->signingContext, pSession->pEncryptedSessionKey,
+                    pSession->encryptedSessionKeyLength);
+        HMAC_Update(&pSession->signingContext, pSession->dataSignature, SHA1_HASH_SIZE);
+        HMAC_Final(&pSession->signingContext, signature, &signatureSize);
+        assert(signatureSize == SHA1_HASH_SIZE);
+        result = memcmp(signature, pSession->headerSignature, SHA1_HASH_SIZE) == 0;
+        HMAC_Init_ex(&pSession->signingContext, NULL, KEY_SIZE, NULL, NULL);
+    }
+    return result;
+}
+
+int FwdLockFile_CheckIntegrity(int fileDesc) {
+    return FwdLockFile_CheckHeaderIntegrity(fileDesc) && FwdLockFile_CheckDataIntegrity(fileDesc);
+}
+
+const char *FwdLockFile_GetContentType(int fileDesc) {
+    int sessionId = FwdLockFile_FindSession(fileDesc);
+    if (sessionId < 0) {
+        return NULL;
+    }
+    return sessionPtrs[sessionId]->pContentType;
+}