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/*
* Copyright (C) 2015 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.
*/
#ifndef __FEC_PRIVATE_H__
#define __FEC_PRIVATE_H__
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <memory>
#include <string>
#include <vector>
#include <crypto_utils/android_pubkey.h>
#include <fec/ecc.h>
#include <fec/io.h>
#include <openssl/obj_mac.h>
#include <openssl/sha.h>
#include <utils/Compat.h>
/* processing parameters */
#define WORK_MIN_THREADS 1
#define WORK_MAX_THREADS 64
/* verity parameters */
#define VERITY_CACHE_BLOCKS 4096
#define VERITY_NO_CACHE UINT64_MAX
/* verity definitions */
#define VERITY_METADATA_SIZE (8 * FEC_BLOCKSIZE)
#define VERITY_TABLE_ARGS 10 /* mandatory arguments */
#define VERITY_MIN_TABLE_SIZE (VERITY_TABLE_ARGS * 2) /* for a sanity check */
#define VERITY_MAX_TABLE_SIZE (VERITY_METADATA_SIZE - sizeof(verity_header))
/* verity header and metadata */
#define VERITY_MAGIC 0xB001B001
#define VERITY_MAGIC_DISABLE 0x46464F56
#define VERITY_VERSION 0
#define VERITY_TABLE_FIELDS 10
#define VERITY_TABLE_VERSION 1
struct verity_header {
uint32_t magic;
uint32_t version;
uint8_t signature[ANDROID_PUBKEY_MODULUS_SIZE];
uint32_t length;
};
/* file handle */
struct ecc_info {
bool valid;
int roots;
int rsn;
uint32_t size;
uint64_t blocks;
uint64_t rounds;
uint64_t start; /* offset in file */
};
struct hashtree_info {
// The number of the input data blocks to compute the hashtree.
uint64_t data_blocks;
// The offset of hashtree in the final image.
uint64_t hash_start;
// The hash concatenation of the input data, i.e. lowest level of the
// hashtree.
std::vector<uint8_t> hash_data;
std::vector<uint8_t> salt;
std::vector<uint8_t> zero_hash;
// Initialize the hashtree offsets and properties with the input parameters.
int initialize(uint64_t hash_start, uint64_t data_blocks,
const std::vector<uint8_t> &salt, int nid);
// Checks if the bytes in 'block' has the expected hash. And the 'index' is
// the block number of is the input block in the filesystem.
bool check_block_hash_with_index(uint64_t index, const uint8_t *block);
// Reads the verity hash tree, validates it against the root hash in `root',
// corrects errors if necessary, and copies valid data blocks for later use
// to 'hashtree'.
int verify_tree(const fec_handle *f, const uint8_t *root);
private:
bool ecc_read_hashes(fec_handle *f, uint64_t hash_offset, uint8_t *hash,
uint64_t data_offset, uint8_t *data);
// Computes the hash for FEC_BLOCKSIZE bytes from buffer 'block' and
// compares it to the expected value in 'expected'.
bool check_block_hash(const uint8_t *expected, const uint8_t *block);
// Computes the hash of 'block' and put the result in 'hash'.
int get_hash(const uint8_t *block, uint8_t *hash);
int nid_; // NID for the hash algorithm.
uint32_t digest_length_;
uint32_t padded_digest_length_;
};
struct verity_info {
bool disabled;
std::string table;
uint64_t metadata_start; /* offset in file */
hashtree_info hashtree;
verity_header header;
verity_header ecc_header;
};
struct fec_handle {
ecc_info ecc;
int fd;
int flags; /* additional flags passed to fec_open */
int mode; /* mode for open(2) */
pthread_mutex_t mutex;
uint64_t errors;
uint64_t data_size;
uint64_t pos;
uint64_t size;
verity_info verity;
hashtree_info hashtree() const {
return verity.hashtree;
}
};
/* I/O helpers */
extern bool raw_pread(int fd, void *buf, size_t count, uint64_t offset);
extern bool raw_pwrite(int fd, const void *buf, size_t count, uint64_t offset);
/* processing functions */
typedef ssize_t (*read_func)(fec_handle *f, uint8_t *dest, size_t count,
uint64_t offset, size_t *errors);
extern ssize_t process(fec_handle *f, uint8_t *buf, size_t count,
uint64_t offset, read_func func);
/* verity functions */
extern uint64_t verity_get_size(uint64_t file_size, uint32_t *verity_levels,
uint32_t *level_hashes,
uint32_t padded_digest_size);
extern int verity_parse_header(fec_handle *f, uint64_t offset);
/* helper macros */
#ifndef unlikely
#define unlikely(x) __builtin_expect(!!(x), 0)
#define likely(x) __builtin_expect(!!(x), 1)
#endif
#ifndef stringify
#define __stringify(x) #x
#define stringify(x) __stringify(x)
#endif
/* warnings, errors, debug output */
#ifdef FEC_NO_KLOG
#define __log(func, type, format, args...) \
fprintf(stderr, "fec: <%d> " type ": %s: " format "\n", \
(int)syscall(SYS_gettid), __FUNCTION__, ##args)
#else
#include <cutils/klog.h>
#define __log(func, type, format, args...) \
KLOG_##func("fec", "<%d> " type ": %s: " format "\n", \
(int)syscall(SYS_gettid), __FUNCTION__, ##args)
#endif
#ifdef NDEBUG
#define debug(format, args...)
#else
#define debug(format, args...) __log(DEBUG, "debug", format, ##args)
#endif
#define warn(format, args...) __log(WARNING, "warning", format, ##args)
#define error(format, args...) __log(ERROR, "error", format, ##args)
#define check(p) \
if (unlikely(!(p))) { \
error("`%s' failed", #p); \
errno = EFAULT; \
return -1; \
}
#endif /* __FEC_PRIVATE_H__ */
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