diff options
Diffstat (limited to 'crypto/lollipop/cryptfs.c')
| -rw-r--r-- | crypto/lollipop/cryptfs.c | 1449 |
1 files changed, 1449 insertions, 0 deletions
diff --git a/crypto/lollipop/cryptfs.c b/crypto/lollipop/cryptfs.c new file mode 100644 index 000000000..496b960ad --- /dev/null +++ b/crypto/lollipop/cryptfs.c @@ -0,0 +1,1449 @@ +/* + * 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. + */ + +/* TO DO: + * 1. Perhaps keep several copies of the encrypted key, in case something + * goes horribly wrong? + * + */ + +#include <sys/types.h> +#include <sys/wait.h> +#include <sys/stat.h> +#include <ctype.h> +#include <fcntl.h> +#include <inttypes.h> +#include <unistd.h> +#include <stdio.h> +#include <sys/ioctl.h> +#include <linux/dm-ioctl.h> +#include <libgen.h> +#include <stdlib.h> +#include <sys/param.h> +#include <string.h> +#include <sys/mount.h> +#include <openssl/evp.h> +#include <errno.h> +#include <linux/kdev_t.h> +#include <time.h> +#include "cryptfs.h" +#include "cutils/properties.h" +#include "crypto_scrypt.h" +#include <hardware/keymaster.h> + +#ifndef min /* already defined by windows.h */ +#define min(a, b) ((a) < (b) ? (a) : (b)) +#endif + +#define UNUSED __attribute__((unused)) + +#define UNUSED __attribute__((unused)) + +#define DM_CRYPT_BUF_SIZE 4096 + +#define HASH_COUNT 2000 +#define KEY_LEN_BYTES 16 +#define IV_LEN_BYTES 16 + +#define KEY_IN_FOOTER "footer" + +// "default_password" encoded into hex (d=0x64 etc) +#define DEFAULT_PASSWORD "64656661756c745f70617373776f7264" + +#define EXT4_FS 1 +#define F2FS_FS 2 + +#define TABLE_LOAD_RETRIES 10 + +#define RSA_KEY_SIZE 2048 +#define RSA_KEY_SIZE_BYTES (RSA_KEY_SIZE / 8) +#define RSA_EXPONENT 0x10001 + +#define RETRY_MOUNT_ATTEMPTS 10 +#define RETRY_MOUNT_DELAY_SECONDS 1 + +char *me = "cryptfs"; + +static unsigned char saved_master_key[KEY_LEN_BYTES]; +static char *saved_mount_point; +static int master_key_saved = 0; +static struct crypt_persist_data *persist_data = NULL; +static char key_fname[PROPERTY_VALUE_MAX] = ""; +static char real_blkdev[PROPERTY_VALUE_MAX] = ""; +static char file_system[PROPERTY_VALUE_MAX] = ""; + +void set_partition_data(const char* block_device, const char* key_location, const char* fs) +{ + strcpy(key_fname, key_location); + strcpy(real_blkdev, block_device); + strcpy(file_system, fs); +} + +static int keymaster_init(keymaster_device_t **keymaster_dev) +{ + int rc; + + const hw_module_t* mod; + rc = hw_get_module_by_class(KEYSTORE_HARDWARE_MODULE_ID, NULL, &mod); + if (rc) { + printf("could not find any keystore module\n"); + goto out; + } + + rc = keymaster_open(mod, keymaster_dev); + if (rc) { + printf("could not open keymaster device in %s (%s)\n", + KEYSTORE_HARDWARE_MODULE_ID, strerror(-rc)); + goto out; + } + + return 0; + +out: + *keymaster_dev = NULL; + return rc; +} + +/* Should we use keymaster? */ +static int keymaster_check_compatibility() +{ + keymaster_device_t *keymaster_dev = 0; + int rc = 0; + + if (keymaster_init(&keymaster_dev)) { + printf("Failed to init keymaster\n"); + rc = -1; + goto out; + } + + printf("keymaster version is %d\n", keymaster_dev->common.module->module_api_version); + +#if (KEYMASTER_HEADER_VERSION >= 3) + if (keymaster_dev->common.module->module_api_version + < KEYMASTER_MODULE_API_VERSION_0_3) { + rc = 0; + goto out; + } + + if (keymaster_dev->flags & KEYMASTER_BLOBS_ARE_STANDALONE) { + rc = 1; + } + +#endif +out: + keymaster_close(keymaster_dev); + return rc; +} + +/* Create a new keymaster key and store it in this footer */ +static int keymaster_create_key(struct crypt_mnt_ftr *ftr) +{ + uint8_t* key = 0; + keymaster_device_t *keymaster_dev = 0; + + if (keymaster_init(&keymaster_dev)) { + printf("Failed to init keymaster\n"); + return -1; + } + + int rc = 0; + + keymaster_rsa_keygen_params_t params; + memset(¶ms, '\0', sizeof(params)); + params.public_exponent = RSA_EXPONENT; + params.modulus_size = RSA_KEY_SIZE; + + size_t key_size; + if (keymaster_dev->generate_keypair(keymaster_dev, TYPE_RSA, ¶ms, + &key, &key_size)) { + printf("Failed to generate keypair\n"); + rc = -1; + goto out; + } + + if (key_size > KEYMASTER_BLOB_SIZE) { + printf("Keymaster key too large for crypto footer\n"); + rc = -1; + goto out; + } + + memcpy(ftr->keymaster_blob, key, key_size); + ftr->keymaster_blob_size = key_size; + +out: + keymaster_close(keymaster_dev); + free(key); + return rc; +} + +/* This signs the given object using the keymaster key. */ +static int keymaster_sign_object(struct crypt_mnt_ftr *ftr, + const unsigned char *object, + const size_t object_size, + unsigned char **signature, + size_t *signature_size) +{ + int rc = 0; + keymaster_device_t *keymaster_dev = 0; + if (keymaster_init(&keymaster_dev)) { + printf("Failed to init keymaster\n"); + return -1; + } + + /* We currently set the digest type to DIGEST_NONE because it's the + * only supported value for keymaster. A similar issue exists with + * PADDING_NONE. Long term both of these should likely change. + */ + keymaster_rsa_sign_params_t params; + params.digest_type = DIGEST_NONE; + params.padding_type = PADDING_NONE; + + unsigned char to_sign[RSA_KEY_SIZE_BYTES]; + size_t to_sign_size = sizeof(to_sign); + memset(to_sign, 0, RSA_KEY_SIZE_BYTES); + + // To sign a message with RSA, the message must satisfy two + // constraints: + // + // 1. The message, when interpreted as a big-endian numeric value, must + // be strictly less than the public modulus of the RSA key. Note + // that because the most significant bit of the public modulus is + // guaranteed to be 1 (else it's an (n-1)-bit key, not an n-bit + // key), an n-bit message with most significant bit 0 always + // satisfies this requirement. + // + // 2. The message must have the same length in bits as the public + // modulus of the RSA key. This requirement isn't mathematically + // necessary, but is necessary to ensure consistency in + // implementations. + switch (ftr->kdf_type) { + case KDF_SCRYPT_KEYMASTER_UNPADDED: + // This is broken: It produces a message which is shorter than + // the public modulus, failing criterion 2. + memcpy(to_sign, object, object_size); + to_sign_size = object_size; + printf("Signing unpadded object\n"); + break; + case KDF_SCRYPT_KEYMASTER_BADLY_PADDED: + // This is broken: Since the value of object is uniformly + // distributed, it produces a message that is larger than the + // public modulus with probability 0.25. + memcpy(to_sign, object, min(RSA_KEY_SIZE_BYTES, object_size)); + printf("Signing end-padded object\n"); + break; + case KDF_SCRYPT_KEYMASTER: + // This ensures the most significant byte of the signed message + // is zero. We could have zero-padded to the left instead, but + // this approach is slightly more robust against changes in + // object size. However, it's still broken (but not unusably + // so) because we really should be using a proper RSA padding + // function, such as OAEP. + // + // TODO(paullawrence): When keymaster 0.4 is available, change + // this to use the padding options it provides. + memcpy(to_sign + 1, object, min(RSA_KEY_SIZE_BYTES - 1, object_size)); + printf("Signing safely-padded object\n"); + break; + default: + printf("Unknown KDF type %d\n", ftr->kdf_type); + return -1; + } + + rc = keymaster_dev->sign_data(keymaster_dev, + ¶ms, + ftr->keymaster_blob, + ftr->keymaster_blob_size, + to_sign, + to_sign_size, + signature, + signature_size); + + keymaster_close(keymaster_dev); + return rc; +} + +/* Store password when userdata is successfully decrypted and mounted. + * Cleared by cryptfs_clear_password + * + * To avoid a double prompt at boot, we need to store the CryptKeeper + * password and pass it to KeyGuard, which uses it to unlock KeyStore. + * Since the entire framework is torn down and rebuilt after encryption, + * we have to use a daemon or similar to store the password. Since vold + * is secured against IPC except from system processes, it seems a reasonable + * place to store this. + * + * password should be cleared once it has been used. + * + * password is aged out after password_max_age_seconds seconds. + */ +static char* password = 0; +static int password_expiry_time = 0; +static const int password_max_age_seconds = 60; + +static void ioctl_init(struct dm_ioctl *io, size_t dataSize, const char *name, unsigned flags) +{ + memset(io, 0, dataSize); + io->data_size = dataSize; + io->data_start = sizeof(struct dm_ioctl); + io->version[0] = 4; + io->version[1] = 0; + io->version[2] = 0; + io->flags = flags; + if (name) { + strncpy(io->name, name, sizeof(io->name)); + } +} + +/** + * Gets the default device scrypt parameters for key derivation time tuning. + * The parameters should lead to about one second derivation time for the + * given device. + */ +static void get_device_scrypt_params(struct crypt_mnt_ftr *ftr) { + const int default_params[] = SCRYPT_DEFAULTS; + int params[] = SCRYPT_DEFAULTS; + char paramstr[PROPERTY_VALUE_MAX]; + char *token; + char *saveptr; + int i; + + property_get(SCRYPT_PROP, paramstr, ""); + if (paramstr[0] != '\0') { + /* + * The token we're looking for should be three integers separated by + * colons (e.g., "12:8:1"). Scan the property to make sure it matches. + */ + for (i = 0, token = strtok_r(paramstr, ":", &saveptr); + token != NULL && i < 3; + i++, token = strtok_r(NULL, ":", &saveptr)) { + char *endptr; + params[i] = strtol(token, &endptr, 10); + + /* + * Check that there was a valid number and it's 8-bit. If not, + * break out and the end check will take the default values. + */ + if ((*token == '\0') || (*endptr != '\0') || params[i] < 0 || params[i] > 255) { + break; + } + } + + /* + * If there were not enough tokens or a token was malformed (not an + * integer), it will end up here and the default parameters can be + * taken. + */ + if ((i != 3) || (token != NULL)) { + printf("bad scrypt parameters '%s' should be like '12:8:1'; using defaults", paramstr); + memcpy(params, default_params, sizeof(params)); + } + } + + ftr->N_factor = params[0]; + ftr->r_factor = params[1]; + ftr->p_factor = params[2]; +} + +static unsigned int get_blkdev_size(int fd) +{ + unsigned int nr_sec; + + if ( (ioctl(fd, BLKGETSIZE, &nr_sec)) == -1) { + nr_sec = 0; + } + + return nr_sec; +} + +static int get_crypt_ftr_info(char **metadata_fname, off64_t *off) +{ + static int cached_data = 0; + static off64_t cached_off = 0; + static char cached_metadata_fname[PROPERTY_VALUE_MAX] = ""; + int fd; + unsigned int nr_sec; + int rc = -1; + + if (!cached_data) { + printf("get_crypt_ftr_info crypto key location: '%s'\n", key_fname); + if (!strcmp(key_fname, KEY_IN_FOOTER)) { + if ( (fd = open(real_blkdev, O_RDWR)) < 0) { + printf("Cannot open real block device %s\n", real_blkdev); + return -1; + } + + if ((nr_sec = get_blkdev_size(fd))) { + /* If it's an encrypted Android partition, the last 16 Kbytes contain the + * encryption info footer and key, and plenty of bytes to spare for future + * growth. + */ + strlcpy(cached_metadata_fname, real_blkdev, sizeof(cached_metadata_fname)); + cached_off = ((off64_t)nr_sec * 512) - CRYPT_FOOTER_OFFSET; + cached_data = 1; + } else { + printf("Cannot get size of block device %s\n", real_blkdev); + } + close(fd); + } else { + strlcpy(cached_metadata_fname, key_fname, sizeof(cached_metadata_fname)); + cached_off = 0; + cached_data = 1; + } + } + + if (cached_data) { + if (metadata_fname) { + *metadata_fname = cached_metadata_fname; + } + if (off) { + *off = cached_off; + } + rc = 0; + } + + return rc; +} + +static inline int unix_read(int fd, void* buff, int len) +{ + return TEMP_FAILURE_RETRY(read(fd, buff, len)); +} + +static inline int unix_write(int fd, const void* buff, int len) +{ + return TEMP_FAILURE_RETRY(write(fd, buff, len)); +} + +static void init_empty_persist_data(struct crypt_persist_data *pdata, int len) +{ + memset(pdata, 0, len); + pdata->persist_magic = PERSIST_DATA_MAGIC; + pdata->persist_valid_entries = 0; +} + +static int get_crypt_ftr_and_key(struct crypt_mnt_ftr *crypt_ftr) +{ + int fd; + unsigned int nr_sec, cnt; + off64_t starting_off; + int rc = -1; + char *fname = NULL; + struct stat statbuf; + + if (get_crypt_ftr_info(&fname, &starting_off)) { + printf("Unable to get crypt_ftr_info\n"); + return -1; + } + if (fname[0] != '/') { + printf("Unexpected value for crypto key location\n"); + return -1; + } + if ( (fd = open(fname, O_RDWR)) < 0) { + printf("Cannot open footer file %s for get\n", fname); + return -1; + } + + /* Make sure it's 16 Kbytes in length */ + fstat(fd, &statbuf); + if (S_ISREG(statbuf.st_mode) && (statbuf.st_size != 0x4000)) { + printf("footer file %s is not the expected size!\n", fname); + goto errout; + } + + /* Seek to the start of the crypt footer */ + if (lseek64(fd, starting_off, SEEK_SET) == -1) { + printf("Cannot seek to real block device footer\n"); + goto errout; + } + + if ( (cnt = read(fd, crypt_ftr, sizeof(struct crypt_mnt_ftr))) != sizeof(struct crypt_mnt_ftr)) { + printf("Cannot read real block device footer\n"); + goto errout; + } + + if (crypt_ftr->magic != CRYPT_MNT_MAGIC) { + printf("Bad magic for real block device %s\n", fname); + goto errout; + } + + if (crypt_ftr->major_version != CURRENT_MAJOR_VERSION) { + printf("Cannot understand major version %d real block device footer; expected %d\n", + crypt_ftr->major_version, CURRENT_MAJOR_VERSION); + goto errout; + } + + if (crypt_ftr->minor_version > CURRENT_MINOR_VERSION) { + printf("Warning: crypto footer minor version %d, expected <= %d, continuing...\n", + crypt_ftr->minor_version, CURRENT_MINOR_VERSION); + } + + /* If this is a verion 1.0 crypt_ftr, make it a 1.1 crypt footer, and update the + * copy on disk before returning. + */ + /*if (crypt_ftr->minor_version < CURRENT_MINOR_VERSION) { + upgrade_crypt_ftr(fd, crypt_ftr, starting_off); + }*/ + + /* Success! */ + rc = 0; + +errout: + close(fd); + return rc; +} + +static int hexdigit (char c) +{ + if (c >= '0' && c <= '9') return c - '0'; + c = tolower(c); + if (c >= 'a' && c <= 'f') return c - 'a' + 10; + return -1; +} + +static unsigned char* convert_hex_ascii_to_key(const char* master_key_ascii, + unsigned int* out_keysize) +{ + unsigned int i; + *out_keysize = 0; + + size_t size = strlen (master_key_ascii); + if (size % 2) { + printf("Trying to convert ascii string of odd length"); + return NULL; + } + + unsigned char* master_key = (unsigned char*) malloc(size / 2); + if (master_key == 0) { + printf("Cannot allocate"); + return NULL; + } + + for (i = 0; i < size; i += 2) { + int high_nibble = hexdigit (master_key_ascii[i]); + int low_nibble = hexdigit (master_key_ascii[i + 1]); + + if(high_nibble < 0 || low_nibble < 0) { + printf("Invalid hex string"); + free (master_key); + return NULL; + } + + master_key[*out_keysize] = high_nibble * 16 + low_nibble; + (*out_keysize)++; + } + + return master_key; +} + +/* Convert a binary key of specified length into an ascii hex string equivalent, + * without the leading 0x and with null termination + */ +static void convert_key_to_hex_ascii(unsigned char *master_key, unsigned int keysize, + char *master_key_ascii) +{ + unsigned int i, a; + unsigned char nibble; + + for (i=0, a=0; i<keysize; i++, a+=2) { + /* For each byte, write out two ascii hex digits */ + nibble = (master_key[i] >> 4) & 0xf; + master_key_ascii[a] = nibble + (nibble > 9 ? 0x37 : 0x30); + + nibble = master_key[i] & 0xf; + master_key_ascii[a+1] = nibble + (nibble > 9 ? 0x37 : 0x30); + } + + /* Add the null termination */ + master_key_ascii[a] = '\0'; + +} + +static int load_crypto_mapping_table(struct crypt_mnt_ftr *crypt_ftr, unsigned char *master_key, + char *real_blk_name, const char *name, int fd, + char *extra_params) +{ + char buffer[DM_CRYPT_BUF_SIZE]; + struct dm_ioctl *io; + struct dm_target_spec *tgt; + char *crypt_params; + char master_key_ascii[129]; /* Large enough to hold 512 bit key and null */ + int i; + + io = (struct dm_ioctl *) buffer; + + /* Load the mapping table for this device */ + tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)]; + + ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); + io->target_count = 1; + tgt->status = 0; + tgt->sector_start = 0; + tgt->length = crypt_ftr->fs_size; + strcpy(tgt->target_type, "crypt"); + + crypt_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec); + convert_key_to_hex_ascii(master_key, crypt_ftr->keysize, master_key_ascii); + sprintf(crypt_params, "%s %s 0 %s 0 %s", crypt_ftr->crypto_type_name, + master_key_ascii, real_blk_name, extra_params); + crypt_params += strlen(crypt_params) + 1; + crypt_params = (char *) (((unsigned long)crypt_params + 7) & ~8); /* Align to an 8 byte boundary */ + tgt->next = crypt_params - buffer; + + for (i = 0; i < TABLE_LOAD_RETRIES; i++) { + if (! ioctl(fd, DM_TABLE_LOAD, io)) { + break; + } + usleep(500000); + } + + if (i == TABLE_LOAD_RETRIES) { + /* We failed to load the table, return an error */ + return -1; + } else { + return i + 1; + } +} + + +static int get_dm_crypt_version(int fd, const char *name, int *version) +{ + char buffer[DM_CRYPT_BUF_SIZE]; + struct dm_ioctl *io; + struct dm_target_versions *v; + int i; + + io = (struct dm_ioctl *) buffer; + + ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); + + if (ioctl(fd, DM_LIST_VERSIONS, io)) { + return -1; + } + + /* Iterate over the returned versions, looking for name of "crypt". + * When found, get and return the version. + */ + v = (struct dm_target_versions *) &buffer[sizeof(struct dm_ioctl)]; + while (v->next) { + if (! strcmp(v->name, "crypt")) { + /* We found the crypt driver, return the version, and get out */ + version[0] = v->version[0]; + version[1] = v->version[1]; + version[2] = v->version[2]; + return 0; + } + v = (struct dm_target_versions *)(((char *)v) + v->next); + } + + return -1; +} + +static int create_crypto_blk_dev(struct crypt_mnt_ftr *crypt_ftr, unsigned char *master_key, + char *real_blk_name, char *crypto_blk_name, const char *name) +{ + char buffer[DM_CRYPT_BUF_SIZE]; + char master_key_ascii[129]; /* Large enough to hold 512 bit key and null */ + char *crypt_params; + struct dm_ioctl *io; + struct dm_target_spec *tgt; + unsigned int minor; + int fd; + int i; + int retval = -1; + int version[3]; + char *extra_params; + int load_count; + + if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) { + printf("Cannot open device-mapper\n"); + goto errout; + } + + io = (struct dm_ioctl *) buffer; + + ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); + if (ioctl(fd, DM_DEV_CREATE, io)) { + printf("Cannot create dm-crypt device\n"); + goto errout; + } + + /* Get the device status, in particular, the name of it's device file */ + ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); + if (ioctl(fd, DM_DEV_STATUS, io)) { + printf("Cannot retrieve dm-crypt device status\n"); + goto errout; + } + minor = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00); + snprintf(crypto_blk_name, MAXPATHLEN, "/dev/block/dm-%u", minor); + + extra_params = ""; + if (! get_dm_crypt_version(fd, name, version)) { + /* Support for allow_discards was added in version 1.11.0 */ + if ((version[0] >= 2) || + ((version[0] == 1) && (version[1] >= 11))) { + extra_params = "1 allow_discards"; + printf("Enabling support for allow_discards in dmcrypt.\n"); + } + } + + load_count = load_crypto_mapping_table(crypt_ftr, master_key, real_blk_name, name, + fd, extra_params); + if (load_count < 0) { + printf("Cannot load dm-crypt mapping table.\n"); + goto errout; + } else if (load_count > 1) { + printf("Took %d tries to load dmcrypt table.\n", load_count); + } + + /* Resume this device to activate it */ + ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); + + if (ioctl(fd, DM_DEV_SUSPEND, io)) { + printf("Cannot resume the dm-crypt device\n"); + goto errout; + } + + /* We made it here with no errors. Woot! */ + retval = 0; + +errout: + close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */ + + return retval; +} + +int delete_crypto_blk_dev(char *name) +{ + int fd; + char buffer[DM_CRYPT_BUF_SIZE]; + struct dm_ioctl *io; + int retval = -1; + + if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) { + printf("Cannot open device-mapper\n"); + goto errout; + } + + io = (struct dm_ioctl *) buffer; + + ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); + if (ioctl(fd, DM_DEV_REMOVE, io)) { + printf("Cannot remove dm-crypt device\n"); + goto errout; + } + + /* We made it here with no errors. Woot! */ + retval = 0; + +errout: + close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */ + + return retval; + +} + +static int pbkdf2(const char *passwd, const unsigned char *salt, + unsigned char *ikey, void *params UNUSED) +{ + printf("Using pbkdf2 for cryptfs KDF"); + + /* Turn the password into a key and IV that can decrypt the master key */ + unsigned int keysize; + char* master_key = (char*)convert_hex_ascii_to_key(passwd, &keysize); + if (!master_key) return -1; + PKCS5_PBKDF2_HMAC_SHA1(master_key, keysize, salt, SALT_LEN, + HASH_COUNT, KEY_LEN_BYTES+IV_LEN_BYTES, ikey); + + memset(master_key, 0, keysize); + free (master_key); + return 0; +} + +static int scrypt(const char *passwd, const unsigned char *salt, + unsigned char *ikey, void *params) +{ + printf("Using scrypt for cryptfs KDF\n"); + + struct crypt_mnt_ftr *ftr = (struct crypt_mnt_ftr *) params; + + int N = 1 << ftr->N_factor; + int r = 1 << ftr->r_factor; + int p = 1 << ftr->p_factor; + + /* Turn the password into a key and IV that can decrypt the master key */ + unsigned int keysize; + unsigned char* master_key = convert_hex_ascii_to_key(passwd, &keysize); + if (!master_key) return -1; + crypto_scrypt(master_key, keysize, salt, SALT_LEN, N, r, p, ikey, + KEY_LEN_BYTES + IV_LEN_BYTES); + + memset(master_key, 0, keysize); + free (master_key); + return 0; +} + +static int scrypt_keymaster(const char *passwd, const unsigned char *salt, + unsigned char *ikey, void *params) +{ + printf("Using scrypt with keymaster for cryptfs KDF\n"); + + int rc; + unsigned int key_size; + size_t signature_size; + unsigned char* signature; + struct crypt_mnt_ftr *ftr = (struct crypt_mnt_ftr *) params; + + int N = 1 << ftr->N_factor; + int r = 1 << ftr->r_factor; + int p = 1 << ftr->p_factor; + + unsigned char* master_key = convert_hex_ascii_to_key(passwd, &key_size); + if (!master_key) { + printf("Failed to convert passwd from hex\n"); + return -1; + } + + rc = crypto_scrypt(master_key, key_size, salt, SALT_LEN, + N, r, p, ikey, KEY_LEN_BYTES + IV_LEN_BYTES); + memset(master_key, 0, key_size); + free(master_key); + + if (rc) { + printf("scrypt failed\n"); + return -1; + } + + if (keymaster_sign_object(ftr, ikey, KEY_LEN_BYTES + IV_LEN_BYTES, + &signature, &signature_size)) { + printf("Signing failed\n"); + return -1; + } + + rc = crypto_scrypt(signature, signature_size, salt, SALT_LEN, + N, r, p, ikey, KEY_LEN_BYTES + IV_LEN_BYTES); + free(signature); + + if (rc) { + printf("scrypt failed\n"); + return -1; + } + + return 0; +} + +static int encrypt_master_key(const char *passwd, const unsigned char *salt, + const unsigned char *decrypted_master_key, + unsigned char *encrypted_master_key, + struct crypt_mnt_ftr *crypt_ftr) +{ + unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ + EVP_CIPHER_CTX e_ctx; + int encrypted_len, final_len; + int rc = 0; + + /* Turn the password into an intermediate key and IV that can decrypt the master key */ + get_device_scrypt_params(crypt_ftr); + + switch (crypt_ftr->kdf_type) { + case KDF_SCRYPT_KEYMASTER_UNPADDED: + case KDF_SCRYPT_KEYMASTER_BADLY_PADDED: + case KDF_SCRYPT_KEYMASTER: + if (keymaster_create_key(crypt_ftr)) { + printf("keymaster_create_key failed"); + return -1; + } + + if (scrypt_keymaster(passwd, salt, ikey, crypt_ftr)) { + printf("scrypt failed"); + return -1; + } + break; + + case KDF_SCRYPT: + if (scrypt(passwd, salt, ikey, crypt_ftr)) { + printf("scrypt failed"); + return -1; + } + break; + + default: + printf("Invalid kdf_type"); + return -1; + } + + /* Initialize the decryption engine */ + if (! EVP_EncryptInit(&e_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) { + printf("EVP_EncryptInit failed\n"); + return -1; + } + EVP_CIPHER_CTX_set_padding(&e_ctx, 0); /* Turn off padding as our data is block aligned */ + + /* Encrypt the master key */ + if (! EVP_EncryptUpdate(&e_ctx, encrypted_master_key, &encrypted_len, + decrypted_master_key, KEY_LEN_BYTES)) { + printf("EVP_EncryptUpdate failed\n"); + return -1; + } + if (! EVP_EncryptFinal(&e_ctx, encrypted_master_key + encrypted_len, &final_len)) { + printf("EVP_EncryptFinal failed\n"); + return -1; + } + + if (encrypted_len + final_len != KEY_LEN_BYTES) { + printf("EVP_Encryption length check failed with %d, %d bytes\n", encrypted_len, final_len); + return -1; + } + + /* Store the scrypt of the intermediate key, so we can validate if it's a + password error or mount error when things go wrong. + Note there's no need to check for errors, since if this is incorrect, we + simply won't wipe userdata, which is the correct default behavior + */ + int N = 1 << crypt_ftr->N_factor; + int r = 1 << crypt_ftr->r_factor; + int p = 1 << crypt_ftr->p_factor; + + rc = crypto_scrypt(ikey, KEY_LEN_BYTES, + crypt_ftr->salt, sizeof(crypt_ftr->salt), N, r, p, + crypt_ftr->scrypted_intermediate_key, + sizeof(crypt_ftr->scrypted_intermediate_key)); + + if (rc) { + printf("encrypt_master_key: crypto_scrypt failed"); + } + + return 0; +} + +static int decrypt_master_key_aux(char *passwd, unsigned char *salt, + unsigned char *encrypted_master_key, + unsigned char *decrypted_master_key, + kdf_func kdf, void *kdf_params, + unsigned char** intermediate_key, + size_t* intermediate_key_size) +{ + unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ + EVP_CIPHER_CTX d_ctx; + int decrypted_len, final_len; + + /* Turn the password into an intermediate key and IV that can decrypt the + master key */ + if (kdf(passwd, salt, ikey, kdf_params)) { + printf("kdf failed"); + return -1; + } + + /* Initialize the decryption engine */ + if (! EVP_DecryptInit(&d_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) { + return -1; + } + EVP_CIPHER_CTX_set_padding(&d_ctx, 0); /* Turn off padding as our data is block aligned */ + /* Decrypt the master key */ + if (! EVP_DecryptUpdate(&d_ctx, decrypted_master_key, &decrypted_len, + encrypted_master_key, KEY_LEN_BYTES)) { + return -1; + } + if (! EVP_DecryptFinal(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) { + return -1; + } + + if (decrypted_len + final_len != KEY_LEN_BYTES) { + return -1; + } + + /* Copy intermediate key if needed by params */ + if (intermediate_key && intermediate_key_size) { + *intermediate_key = (unsigned char*) malloc(KEY_LEN_BYTES); + if (intermediate_key) { + memcpy(*intermediate_key, ikey, KEY_LEN_BYTES); + *intermediate_key_size = KEY_LEN_BYTES; + } + } + + return 0; +} + +static void get_kdf_func(struct crypt_mnt_ftr *ftr, kdf_func *kdf, void** kdf_params) +{ + if (ftr->kdf_type == KDF_SCRYPT_KEYMASTER_UNPADDED || + ftr->kdf_type == KDF_SCRYPT_KEYMASTER_BADLY_PADDED || + ftr->kdf_type == KDF_SCRYPT_KEYMASTER) { + *kdf = scrypt_keymaster; + *kdf_params = ftr; + } else if (ftr->kdf_type == KDF_SCRYPT) { + *kdf = scrypt; + *kdf_params = ftr; + } else { + *kdf = pbkdf2; + *kdf_params = NULL; + } +} + +static int decrypt_master_key(char *passwd, unsigned char *decrypted_master_key, + struct crypt_mnt_ftr *crypt_ftr, + unsigned char** intermediate_key, + size_t* intermediate_key_size) +{ + kdf_func kdf; + void *kdf_params; + int ret; + + get_kdf_func(crypt_ftr, &kdf, &kdf_params); + ret = decrypt_master_key_aux(passwd, crypt_ftr->salt, crypt_ftr->master_key, + decrypted_master_key, kdf, kdf_params, + intermediate_key, intermediate_key_size); + if (ret != 0) { + printf("failure decrypting master key"); + } + + return ret; +} + +static int test_mount_encrypted_fs(struct crypt_mnt_ftr* crypt_ftr, + char *passwd, char *mount_point, char *label) +{ + /* Allocate enough space for a 256 bit key, but we may use less */ + unsigned char decrypted_master_key[32]; + char crypto_blkdev[MAXPATHLEN]; + char tmp_mount_point[64]; + unsigned int orig_failed_decrypt_count; + int rc; + kdf_func kdf; + void *kdf_params; + int use_keymaster = 0; + int upgrade = 0; + unsigned char* intermediate_key = 0; + size_t intermediate_key_size = 0; + + printf("crypt_ftr->fs_size = %lld\n", crypt_ftr->fs_size); + orig_failed_decrypt_count = crypt_ftr->failed_decrypt_count; + + if (! (crypt_ftr->flags & CRYPT_MNT_KEY_UNENCRYPTED) ) { + if (decrypt_master_key(passwd, decrypted_master_key, crypt_ftr, + &intermediate_key, &intermediate_key_size)) { + printf("Failed to decrypt master key\n"); + rc = -1; + goto errout; + } + } + + // Create crypto block device - all (non fatal) code paths + // need it + if (create_crypto_blk_dev(crypt_ftr, decrypted_master_key, + real_blkdev, crypto_blkdev, label)) { + printf("Error creating decrypted block device\n"); + rc = -1; + goto errout; + } + + /* Work out if the problem is the password or the data */ + unsigned char scrypted_intermediate_key[sizeof(crypt_ftr-> + scrypted_intermediate_key)]; + int N = 1 << crypt_ftr->N_factor; + int r = 1 << crypt_ftr->r_factor; + int p = 1 << crypt_ftr->p_factor; + + rc = crypto_scrypt(intermediate_key, intermediate_key_size, + crypt_ftr->salt, sizeof(crypt_ftr->salt), + N, r, p, scrypted_intermediate_key, + sizeof(scrypted_intermediate_key)); + + // Does the key match the crypto footer? + if (rc == 0 && memcmp(scrypted_intermediate_key, + crypt_ftr->scrypted_intermediate_key, + sizeof(scrypted_intermediate_key)) == 0) { + printf("Password matches\n"); + rc = 0; + } else { + /* Try mounting the file system anyway, just in case the problem's with + * the footer, not the key. */ + sprintf(tmp_mount_point, "%s/tmp_mnt", mount_point); + mkdir(tmp_mount_point, 0755); + if (mount(crypto_blkdev, tmp_mount_point, file_system, NULL, NULL) != 0) { + printf("Error temp mounting decrypted block device '%s'\n", crypto_blkdev); + delete_crypto_blk_dev(label); + + rc = ++crypt_ftr->failed_decrypt_count; + //put_crypt_ftr_and_key(crypt_ftr); // Do not penalize for attempting to decrypt in recovery + } else { + /* Success! */ + printf("Password did not match but decrypted drive mounted - continue\n"); + umount(tmp_mount_point); + rc = 0; + } + } + + if (rc == 0) { + /*crypt_ftr->failed_decrypt_count = 0; + if (orig_failed_decrypt_count != 0) { + put_crypt_ftr_and_key(crypt_ftr); + }*/ + + /* Save the name of the crypto block device + * so we can mount it when restarting the framework. */ + property_set("ro.crypto.fs_crypto_blkdev", crypto_blkdev); + + /* Also save a the master key so we can reencrypted the key + * the key when we want to change the password on it. */ + /*memcpy(saved_master_key, decrypted_master_key, KEY_LEN_BYTES); + saved_mount_point = strdup(mount_point); + master_key_saved = 1; + printf("%s(): Master key saved\n", __FUNCTION__);*/ + rc = 0; + + // Upgrade if we're not using the latest KDF. + /*use_keymaster = keymaster_check_compatibility(); + if (crypt_ftr->kdf_type == KDF_SCRYPT_KEYMASTER) { + // Don't allow downgrade + } else if (use_keymaster == 1 && crypt_ftr->kdf_type != KDF_SCRYPT_KEYMASTER) { + crypt_ftr->kdf_type = KDF_SCRYPT_KEYMASTER; + upgrade = 1; + } else if (use_keymaster == 0 && crypt_ftr->kdf_type != KDF_SCRYPT) { + crypt_ftr->kdf_type = KDF_SCRYPT; + upgrade = 1; + } + + if (upgrade) { + rc = encrypt_master_key(passwd, crypt_ftr->salt, saved_master_key, + crypt_ftr->master_key, crypt_ftr); + if (!rc) { + rc = put_crypt_ftr_and_key(crypt_ftr); + } + printf("Key Derivation Function upgrade: rc=%d\n", rc); + + // Do not fail even if upgrade failed - machine is bootable + // Note that if this code is ever hit, there is a *serious* problem + // since KDFs should never fail. You *must* fix the kdf before + // proceeding! + if (rc) { + printf("Upgrade failed with error %d," + " but continuing with previous state\n", + rc); + rc = 0; + } + }*/ + } + + errout: + if (intermediate_key) { + memset(intermediate_key, 0, intermediate_key_size); + free(intermediate_key); + } + return rc; +} + +/* Called by vold when it wants to undo the crypto mapping of a volume it + * manages. This is usually in response to a factory reset, when we want + * to undo the crypto mapping so the volume is formatted in the clear. + */ +int cryptfs_revert_volume(const char *label) +{ + return delete_crypto_blk_dev((char *)label); +} + +int check_unmounted_and_get_ftr(struct crypt_mnt_ftr* crypt_ftr) +{ + char encrypted_state[PROPERTY_VALUE_MAX]; + property_get("ro.crypto.state", encrypted_state, ""); + if ( master_key_saved || strcmp(encrypted_state, "encrypted") ) { + printf("encrypted fs already validated or not running with encryption," + " aborting\n"); + //return -1; + } + + if (get_crypt_ftr_and_key(crypt_ftr)) { + printf("Error getting crypt footer and key\n"); + return -1; + } + + return 0; +} + +/* + * TODO - transition patterns to new format in calling code + * and remove this vile hack, and the use of hex in + * the password passing code. + * + * Patterns are passed in zero based (i.e. the top left dot + * is represented by zero, the top middle one etc), but we want + * to store them '1' based. + * This is to allow us to migrate the calling code to use this + * convention. It also solves a nasty problem whereby scrypt ignores + * trailing zeros, so patterns ending at the top left could be + * truncated, and similarly, you could add the top left to any + * pattern and still match. + * adjust_passwd is a hack function that returns the alternate representation + * if the password appears to be a pattern (hex numbers all less than 09) + * If it succeeds we need to try both, and in particular try the alternate + * first. If the original matches, then we need to update the footer + * with the alternate. + * All code that accepts passwords must adjust them first. Since + * cryptfs_check_passwd is always the first function called after a migration + * (and indeed on any boot) we only need to do the double try in this + * function. + */ +char* adjust_passwd(const char* passwd) +{ + size_t index, length; + + if (!passwd) { + return 0; + } + + // Check even length. Hex encoded passwords are always + // an even length, since each character encodes to two characters. + length = strlen(passwd); + if (length % 2) { + printf("Password not correctly hex encoded."); + return 0; + } + + // Check password is old-style pattern - a collection of hex + // encoded bytes less than 9 (00 through 08) + for (index = 0; index < length; index +=2) { + if (passwd[index] != '0' + || passwd[index + 1] < '0' || passwd[index + 1] > '8') { + return 0; + } + } + + // Allocate room for adjusted passwd and null terminate + char* adjusted = malloc(length + 1); + adjusted[length] = 0; + + // Add 0x31 ('1') to each character + for (index = 0; index < length; index += 2) { + // output is 31 through 39 so set first byte to three, second to src + 1 + adjusted[index] = '3'; + adjusted[index + 1] = passwd[index + 1] + 1; + } + + return adjusted; +} + +/* + * Passwords in L get passed from Android to cryptfs in hex, so a '1' + * gets converted to '31' where 31 is 0x31 which is the ascii character + * code in hex of the character '1'. This function will convert the + * regular character codes to their hexadecimal representation to make + * decrypt work properly with Android 5.0 lollipop decryption. + */ +char* hexadj_passwd(const char* passwd) +{ + size_t index, length; + char* ptr = passwd; + + if (!passwd) { + return 0; + } + + length = strlen(passwd); + + // Allocate room for hex passwd and null terminate + char* hex = malloc((length * 2) + 1); + hex[length * 2] = 0; + + // Convert to hex + for (index = 0; index < length; index++) { + sprintf(hex + (index * 2), "%02X", *ptr); + ptr++; + } + + return hex; +} + +int cryptfs_check_footer() +{ + int rc = -1; + struct crypt_mnt_ftr crypt_ftr; + + rc = get_crypt_ftr_and_key(&crypt_ftr); + + return rc; +} + +int cryptfs_check_passwd(char *passwd) +{ + struct crypt_mnt_ftr crypt_ftr; + int rc; + + rc = check_unmounted_and_get_ftr(&crypt_ftr); + if (rc) + return rc; + + char* adjusted_passwd = adjust_passwd(passwd); + char* hex_passwd = hexadj_passwd(passwd); + + if (adjusted_passwd) { + int failed_decrypt_count = crypt_ftr.failed_decrypt_count; + rc = test_mount_encrypted_fs(&crypt_ftr, adjusted_passwd, + DATA_MNT_POINT, "userdata"); + + // Maybe the original one still works? + if (rc) { + // Don't double count this failure + crypt_ftr.failed_decrypt_count = failed_decrypt_count; + rc = test_mount_encrypted_fs(&crypt_ftr, passwd, + DATA_MNT_POINT, "userdata"); + if (!rc) { + // cryptfs_changepw also adjusts so pass original + // Note that adjust_passwd only recognises patterns + // so we can safely use CRYPT_TYPE_PATTERN + printf("TWRP NOT Updating pattern to new format"); + //cryptfs_changepw(CRYPT_TYPE_PATTERN, passwd); + } else if (hex_passwd) { + rc = test_mount_encrypted_fs(&crypt_ftr, hex_passwd, + DATA_MNT_POINT, "userdata"); + } + } + free(adjusted_passwd); + } else { + rc = test_mount_encrypted_fs(&crypt_ftr, passwd, + DATA_MNT_POINT, "userdata"); + if (rc && hex_passwd) { + rc = test_mount_encrypted_fs(&crypt_ftr, hex_passwd, + DATA_MNT_POINT, "userdata"); + } + } + + if (hex_passwd) + free(hex_passwd); + + /*if (rc == 0 && crypt_ftr.crypt_type != CRYPT_TYPE_DEFAULT) { + printf("cryptfs_check_passwd update expiry time?\n"); + cryptfs_clear_password(); + password = strdup(passwd); + struct timespec now; + clock_gettime(CLOCK_BOOTTIME, &now); + password_expiry_time = now.tv_sec + password_max_age_seconds; + }*/ + + return rc; +} + +int cryptfs_verify_passwd(char *passwd) +{ + struct crypt_mnt_ftr crypt_ftr; + /* Allocate enough space for a 256 bit key, but we may use less */ + unsigned char decrypted_master_key[32]; + char encrypted_state[PROPERTY_VALUE_MAX]; + int rc; + + property_get("ro.crypto.state", encrypted_state, ""); + if (strcmp(encrypted_state, "encrypted") ) { + printf("device not encrypted, aborting"); + return -2; + } + + if (!master_key_saved) { + printf("encrypted fs not yet mounted, aborting"); + return -1; + } + + if (!saved_mount_point) { + printf("encrypted fs failed to save mount point, aborting"); + return -1; + } + + if (get_crypt_ftr_and_key(&crypt_ftr)) { + printf("Error getting crypt footer and key\n"); + return -1; + } + + if (crypt_ftr.flags & CRYPT_MNT_KEY_UNENCRYPTED) { + /* If the device has no password, then just say the password is valid */ + rc = 0; + } else { + char* adjusted_passwd = adjust_passwd(passwd); + if (adjusted_passwd) { + passwd = adjusted_passwd; + } + + decrypt_master_key(passwd, decrypted_master_key, &crypt_ftr, 0, 0); + if (!memcmp(decrypted_master_key, saved_master_key, crypt_ftr.keysize)) { + /* They match, the password is correct */ + rc = 0; + } else { + /* If incorrect, sleep for a bit to prevent dictionary attacks */ + sleep(1); + rc = 1; + } + + free(adjusted_passwd); + } + + return rc; +} + +/* Initialize a crypt_mnt_ftr structure. The keysize is + * defaulted to 16 bytes, and the filesystem size to 0. + * Presumably, at a minimum, the caller will update the + * filesystem size and crypto_type_name after calling this function. + */ +static int cryptfs_init_crypt_mnt_ftr(struct crypt_mnt_ftr *ftr) +{ + off64_t off; + + memset(ftr, 0, sizeof(struct crypt_mnt_ftr)); + ftr->magic = CRYPT_MNT_MAGIC; + ftr->major_version = CURRENT_MAJOR_VERSION; + ftr->minor_version = CURRENT_MINOR_VERSION; + ftr->ftr_size = sizeof(struct crypt_mnt_ftr); + ftr->keysize = KEY_LEN_BYTES; + + switch (keymaster_check_compatibility()) { + case 1: + ftr->kdf_type = KDF_SCRYPT_KEYMASTER; + break; + + case 0: + ftr->kdf_type = KDF_SCRYPT; + break; + + default: + printf("keymaster_check_compatibility failed"); + return -1; + } + + get_device_scrypt_params(ftr); + + ftr->persist_data_size = CRYPT_PERSIST_DATA_SIZE; + if (get_crypt_ftr_info(NULL, &off) == 0) { + ftr->persist_data_offset[0] = off + CRYPT_FOOTER_TO_PERSIST_OFFSET; + ftr->persist_data_offset[1] = off + CRYPT_FOOTER_TO_PERSIST_OFFSET + + ftr->persist_data_size; + } + + return 0; +} + +/* Returns type of the password, default, pattern, pin or password. + */ +int cryptfs_get_password_type(void) +{ + struct crypt_mnt_ftr crypt_ftr; + + if (get_crypt_ftr_and_key(&crypt_ftr)) { + printf("Error getting crypt footer and key\n"); + return -1; + } + + if (crypt_ftr.flags & CRYPT_INCONSISTENT_STATE) { + return -1; + } + + return crypt_ftr.crypt_type; +} |