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// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by the GPL v2 license that can
// be found in the LICENSE file.
//
// Implementation of FileHasher
#define __STDC_LIMIT_MACROS 1
#define __STDC_FORMAT_MACROS 1
#include <errno.h>
#include <inttypes.h>
#include <stdint.h>
#include <asm/page.h>
#include <linux/device-mapper.h>
#include <linux/kernel.h>
#include "verity/file_hasher.h"
#include "verity/logging.h"
namespace verity {
// Simple helper for Initialize.
template <typename T>
static inline bool power_of_two(T num) {
if (num == 0)
return false;
if (!(num & (num - 1)))
return true;
return false;
}
bool FileHasher::Initialize(simple_file::File* source,
simple_file::File* destination,
unsigned int blocks,
const char* alg) {
if (!alg || !source || !destination) {
LOG(ERROR) << "Invalid arguments supplied to Initialize";
LOG(INFO) << "s: " << source << " d: " << destination;
return false;
}
if (source_ || destination_) {
LOG(ERROR) << "Initialize called more than once";
return false;
}
if (blocks > source->Size() / PAGE_SIZE) {
LOG(ERROR) << blocks << " blocks exceeds image size of " << source->Size();
return false;
} else if (blocks == 0) {
blocks = source->Size() / PAGE_SIZE;
if (source->Size() % PAGE_SIZE) {
LOG(ERROR) << "The source file size must be divisible by the block size";
LOG(ERROR) << "Size: " << source->Size();
LOG(INFO) << "Suggested size: " << ALIGN(source->Size(), PAGE_SIZE);
return false;
}
}
alg_ = alg;
source_ = source;
destination_ = destination;
block_limit_ = blocks;
// Now we initialize the tree
if (dm_bht_create(&tree_, block_limit_, alg_)) {
LOG(ERROR) << "Could not create the BH tree";
return false;
}
sectors_ = dm_bht_sectors(&tree_);
hash_data_ = new u8[verity_to_bytes(sectors_)];
// No reading is needed.
dm_bht_set_read_cb(&tree_, dm_bht_zeroread_callback);
dm_bht_set_buffer(&tree_, hash_data_);
return true;
}
bool FileHasher::Store() {
return destination_->WriteAt(verity_to_bytes(sectors_), hash_data_, 0);
}
bool FileHasher::Hash() {
// TODO(wad) abstract size when dm-bht needs to do break from PAGE_SIZE
u8 block_data[PAGE_SIZE];
uint32_t block = 0;
while (block < block_limit_) {
if (!source_->Read(PAGE_SIZE, block_data)) {
LOG(ERROR) << "Failed to read for block: " << block;
return false;
}
if (dm_bht_store_block(&tree_, block, block_data)) {
LOG(ERROR) << "Failed to store block " << block;
return false;
}
++block;
}
return !dm_bht_compute(&tree_);
}
const char* FileHasher::RandomSalt() {
uint8_t buf[DM_BHT_SALT_SIZE];
const char urandom_path[] = "/dev/urandom";
simple_file::File source;
LOG_IF(FATAL, !source.Initialize(urandom_path, O_RDONLY, NULL))
<< "Failed to open the random source: " << urandom_path;
PLOG_IF(FATAL, !source.Read(sizeof(buf), buf))
<< "Failed to read the random source";
for (size_t i = 0; i < sizeof(buf); ++i) {
// NOLINTNEXTLINE(runtime/printf)
sprintf(&random_salt_[i * 2], "%02x", buf[i]);
}
random_salt_[sizeof(random_salt_) - 1] = '\0';
return random_salt_;
}
void FileHasher::PrintTable(bool colocated) {
// Grab the digest (up to 1kbit supported)
uint8_t digest[128];
char hexsalt[DM_BHT_SALT_SIZE * 2 + 1];
bool have_salt;
dm_bht_root_hexdigest(&tree_, digest, sizeof(digest));
have_salt = dm_bht_salt(&tree_, hexsalt) == 0;
// TODO(wad) later support sizes that need 64-bit sectors.
unsigned int hash_start = 0;
unsigned int root_end = to_sector(block_limit_ << PAGE_SHIFT);
if (colocated)
hash_start = root_end;
printf(
"0 %u verity payload=ROOT_DEV hashtree=HASH_DEV hashstart=%u alg=%s "
"root_hexdigest=%s",
root_end, hash_start, alg_, digest);
if (have_salt)
printf(" salt=%s", hexsalt);
printf("\n");
}
} // namespace verity