/*
* Copyright (C) 2014 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.
*/
// This program takes a file on an ext4 filesystem and produces a list
// of the blocks that file occupies, which enables the file contents
// to be read directly from the block device without mounting the
// filesystem.
//
// If the filesystem is using an encrypted block device, it will also
// read the file and rewrite it to the same blocks of the underlying
// (unencrypted) block device, so the file contents can be read
// without the need for the decryption key.
//
// The output of this program is a "block map" which looks like this:
//
// /dev/block/platform/msm_sdcc.1/by-name/userdata # block device
// 49652 4096 # file size in bytes, block size
// 3 # count of block ranges
// 1000 1008 # block range 0
// 2100 2102 # ... block range 1
// 30 33 # ... block range 2
//
// Each block range represents a half-open interval; the line "30 33"
// reprents the blocks [30, 31, 32].
//
// Recovery can take this block map file and retrieve the underlying
// file data to use as an update package.
#include <errno.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <base/file.h>
#include <base/strings.h>
#include <cutils/android_reboot.h>
#include <cutils/properties.h>
#include <fs_mgr.h>
#define LOG_TAG "uncrypt"
#include <log/log.h>
#define WINDOW_SIZE 5
static const std::string cache_block_map = "/cache/recovery/block.map";
static const std::string status_file = "/cache/recovery/uncrypt_status";
static const std::string uncrypt_file = "/cache/recovery/uncrypt_file";
static struct fstab* fstab = NULL;
static int write_at_offset(unsigned char* buffer, size_t size, int wfd, off64_t offset) {
if (TEMP_FAILURE_RETRY(lseek64(wfd, offset, SEEK_SET)) == -1) {
ALOGE("error seeking to offset %lld: %s\n", offset, strerror(errno));
return -1;
}
size_t written = 0;
while (written < size) {
ssize_t wrote = TEMP_FAILURE_RETRY(write(wfd, buffer + written, size - written));
if (wrote == -1) {
ALOGE("error writing offset %lld: %s\n", (offset + written), strerror(errno));
return -1;
}
written += wrote;
}
return 0;
}
static void add_block_to_ranges(int** ranges, int* range_alloc, int* range_used, int new_block) {
// If the current block start is < 0, set the start to the new
// block. (This only happens for the very first block of the very
// first range.)
if ((*ranges)[*range_used*2-2] < 0) {
(*ranges)[*range_used*2-2] = new_block;
(*ranges)[*range_used*2-1] = new_block;
}
if (new_block == (*ranges)[*range_used*2-1]) {
// If the new block comes immediately after the current range,
// all we have to do is extend the current range.
++(*ranges)[*range_used*2-1];
} else {
// We need to start a new range.
// If there isn't enough room in the array, we need to expand it.
if (*range_used >= *range_alloc) {
*range_alloc *= 2;
*ranges = reinterpret_cast<int*>(realloc(*ranges, *range_alloc * 2 * sizeof(int)));
}
++*range_used;
(*ranges)[*range_used*2-2] = new_block;
(*ranges)[*range_used*2-1] = new_block+1;
}
}
static struct fstab* read_fstab() {
fstab = NULL;
// The fstab path is always "/fstab.${ro.hardware}".
char fstab_path[PATH_MAX+1] = "/fstab.";
if (!property_get("ro.hardware", fstab_path+strlen(fstab_path), "")) {
ALOGE("failed to get ro.hardware\n");
return NULL;
}
fstab = fs_mgr_read_fstab(fstab_path);
if (!fstab) {
ALOGE("failed to read %s\n", fstab_path);
return NULL;
}
return fstab;
}
static const char* find_block_device(const char* path, bool* encryptable, bool* encrypted) {
// Look for a volume whose mount point is the prefix of path and
// return its block device. Set encrypted if it's currently
// encrypted.
for (int i = 0; i < fstab->num_entries; ++i) {
struct fstab_rec* v = &fstab->recs[i];
if (!v->mount_point) {
continue;
}
int len = strlen(v->mount_point);
if (strncmp(path, v->mount_point, len) == 0 &&
(path[len] == '/' || path[len] == 0)) {
*encrypted = false;
*encryptable = false;
if (fs_mgr_is_encryptable(v)) {
*encryptable = true;
char buffer[PROPERTY_VALUE_MAX+1];
if (property_get("ro.crypto.state", buffer, "") &&
strcmp(buffer, "encrypted") == 0) {
*encrypted = true;
}
}
return v->blk_device;
}
}
return NULL;
}
// Parse uncrypt_file to find the update package name.
static bool find_uncrypt_package(std::string& package_name)
{
if (!android::base::ReadFileToString(uncrypt_file, &package_name)) {
ALOGE("failed to open \"%s\": %s\n", uncrypt_file.c_str(), strerror(errno));
return false;
}
// Remove the trailing '\n' if present.
package_name = android::base::Trim(package_name);
return true;
}
static int produce_block_map(const char* path, const char* map_file, const char* blk_dev,
bool encrypted, int status_fd) {
int mapfd = open(map_file, O_WRONLY | O_CREAT | O_SYNC, S_IRUSR | S_IWUSR);
if (mapfd == -1) {
ALOGE("failed to open %s\n", map_file);
return -1;
}
FILE* mapf = fdopen(mapfd, "w");
// Make sure we can write to the status_file.
if (!android::base::WriteStringToFd("0\n", status_fd)) {
ALOGE("failed to update \"%s\"\n", status_file.c_str());
return -1;
}
struct stat sb;
int ret = stat(path, &sb);
if (ret != 0) {
ALOGE("failed to stat %s\n", path);
return -1;
}
ALOGI(" block size: %ld bytes\n", (long)sb.st_blksize);
int blocks = ((sb.st_size-1) / sb.st_blksize) + 1;
ALOGI(" file size: %lld bytes, %d blocks\n", (long long)sb.st_size, blocks);
int range_alloc = 1;
int range_used = 1;
int* ranges = reinterpret_cast<int*>(malloc(range_alloc * 2 * sizeof(int)));
ranges[0] = -1;
ranges[1] = -1;
fprintf(mapf, "%s\n%lld %lu\n", blk_dev, (long long)sb.st_size, (unsigned long)sb.st_blksize);
unsigned char* buffers[WINDOW_SIZE];
if (encrypted) {
for (size_t i = 0; i < WINDOW_SIZE; ++i) {
buffers[i] = reinterpret_cast<unsigned char*>(malloc(sb.st_blksize));
}
}
int head_block = 0;
int head = 0, tail = 0;
size_t pos = 0;
int fd = open(path, O_RDONLY);
if (fd < 0) {
ALOGE("failed to open fd for reading: %s\n", strerror(errno));
return -1;
}
int wfd = -1;
if (encrypted) {
wfd = open(blk_dev, O_WRONLY | O_SYNC);
if (wfd < 0) {
ALOGE("failed to open fd for writing: %s\n", strerror(errno));
return -1;
}
}
int last_progress = 0;
while (pos < sb.st_size) {
// Update the status file, progress must be between [0, 99].
int progress = static_cast<int>(100 * (double(pos) / double(sb.st_size)));
if (progress > last_progress) {
last_progress = progress;
android::base::WriteStringToFd(std::to_string(progress) + "\n", status_fd);
}
if ((tail+1) % WINDOW_SIZE == head) {
// write out head buffer
int block = head_block;
ret = ioctl(fd, FIBMAP, &block);
if (ret != 0) {
ALOGE("failed to find block %d\n", head_block);
return -1;
}
add_block_to_ranges(&ranges, &range_alloc, &range_used, block);
if (encrypted) {
if (write_at_offset(buffers[head], sb.st_blksize, wfd,
(off64_t)sb.st_blksize * block) != 0) {
return -1;
}
}
head = (head + 1) % WINDOW_SIZE;
++head_block;
}
// read next block to tail
if (encrypted) {
size_t so_far = 0;
while (so_far < sb.st_blksize && pos < sb.st_size) {
ssize_t this_read =
TEMP_FAILURE_RETRY(read(fd, buffers[tail] + so_far, sb.st_blksize - so_far));
if (this_read == -1) {
ALOGE("failed to read: %s\n", strerror(errno));
return -1;
}
so_far += this_read;
pos += this_read;
}
} else {
// If we're not encrypting; we don't need to actually read
// anything, just skip pos forward as if we'd read a
// block.
pos += sb.st_blksize;
}
tail = (tail+1) % WINDOW_SIZE;
}
while (head != tail) {
// write out head buffer
int block = head_block;
ret = ioctl(fd, FIBMAP, &block);
if (ret != 0) {
ALOGE("failed to find block %d\n", head_block);
return -1;
}
add_block_to_ranges(&ranges, &range_alloc, &range_used, block);
if (encrypted) {
if (write_at_offset(buffers[head], sb.st_blksize, wfd,
(off64_t)sb.st_blksize * block) != 0) {
return -1;
}
}
head = (head + 1) % WINDOW_SIZE;
++head_block;
}
fprintf(mapf, "%d\n", range_used);
for (int i = 0; i < range_used; ++i) {
fprintf(mapf, "%d %d\n", ranges[i*2], ranges[i*2+1]);
}
if (fsync(mapfd) == -1) {
ALOGE("failed to fsync \"%s\": %s\n", map_file, strerror(errno));
return -1;
}
fclose(mapf);
close(fd);
if (encrypted) {
if (fsync(wfd) == -1) {
ALOGE("failed to fsync \"%s\": %s\n", blk_dev, strerror(errno));
return -1;
}
close(wfd);
}
return 0;
}
static void wipe_misc() {
ALOGI("removing old commands from misc");
for (int i = 0; i < fstab->num_entries; ++i) {
struct fstab_rec* v = &fstab->recs[i];
if (!v->mount_point) continue;
if (strcmp(v->mount_point, "/misc") == 0) {
int fd = open(v->blk_device, O_WRONLY | O_SYNC);
uint8_t zeroes[1088]; // sizeof(bootloader_message) from recovery
memset(zeroes, 0, sizeof(zeroes));
size_t written = 0;
size_t size = sizeof(zeroes);
while (written < size) {
ssize_t w = TEMP_FAILURE_RETRY(write(fd, zeroes, size-written));
if (w == -1) {
ALOGE("zero write failed: %s\n", strerror(errno));
return;
} else {
written += w;
}
}
if (fsync(fd) == -1) {
ALOGE("failed to fsync \"%s\": %s\n", v->blk_device, strerror(errno));
close(fd);
return;
}
close(fd);
}
}
}
static void reboot_to_recovery() {
ALOGI("rebooting to recovery");
property_set("sys.powerctl", "reboot,recovery");
while (true) {
pause();
}
ALOGE("reboot didn't succeed?");
}
int uncrypt(const char* input_path, const char* map_file, int status_fd) {
ALOGI("update package is \"%s\"", input_path);
// Turn the name of the file we're supposed to convert into an
// absolute path, so we can find what filesystem it's on.
char path[PATH_MAX+1];
if (realpath(input_path, path) == NULL) {
ALOGE("failed to convert \"%s\" to absolute path: %s", input_path, strerror(errno));
return 1;
}
if (read_fstab() == NULL) {
return 1;
}
bool encryptable;
bool encrypted;
const char* blk_dev = find_block_device(path, &encryptable, &encrypted);
if (blk_dev == NULL) {
ALOGE("failed to find block device for %s", path);
return 1;
}
// If the filesystem it's on isn't encrypted, we only produce the
// block map, we don't rewrite the file contents (it would be
// pointless to do so).
ALOGI("encryptable: %s\n", encryptable ? "yes" : "no");
ALOGI(" encrypted: %s\n", encrypted ? "yes" : "no");
// Recovery supports installing packages from 3 paths: /cache,
// /data, and /sdcard. (On a particular device, other locations
// may work, but those are three we actually expect.)
//
// On /data we want to convert the file to a block map so that we
// can read the package without mounting the partition. On /cache
// and /sdcard we leave the file alone.
if (strncmp(path, "/data/", 6) == 0) {
ALOGI("writing block map %s", map_file);
if (produce_block_map(path, map_file, blk_dev, encrypted, status_fd) != 0) {
return 1;
}
}
return 0;
}
int main(int argc, char** argv) {
const char* input_path;
const char* map_file;
if (argc != 3 && argc != 1 && (argc == 2 && strcmp(argv[1], "--reboot") != 0)) {
fprintf(stderr, "usage: %s [--reboot] [<transform_path> <map_file>]\n", argv[0]);
return 2;
}
// When uncrypt is started with "--reboot", it wipes misc and reboots.
// Otherwise it uncrypts the package and writes the block map.
if (argc == 2) {
if (read_fstab() == NULL) {
return 1;
}
wipe_misc();
reboot_to_recovery();
} else {
// The pipe has been created by the system server.
int status_fd = open(status_file.c_str(), O_WRONLY | O_CREAT | O_SYNC, S_IRUSR | S_IWUSR);
if (status_fd == -1) {
ALOGE("failed to open pipe \"%s\": %s\n", status_file.c_str(), strerror(errno));
return 1;
}
if (argc == 3) {
// when command-line args are given this binary is being used
// for debugging.
input_path = argv[1];
map_file = argv[2];
} else {
std::string package;
if (!find_uncrypt_package(package)) {
android::base::WriteStringToFd("-1\n", status_fd);
close(status_fd);
return 1;
}
input_path = package.c_str();
map_file = cache_block_map.c_str();
}
int status = uncrypt(input_path, map_file, status_fd);
if (status != 0) {
android::base::WriteStringToFd("-1\n", status_fd);
close(status_fd);
return 1;
}
android::base::WriteStringToFd("100\n", status_fd);
close(status_fd);
}
return 0;
}
