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Diffstat (limited to 'uncrypt/uncrypt.cpp')
| -rw-r--r-- | uncrypt/uncrypt.cpp | 465 |
1 files changed, 465 insertions, 0 deletions
diff --git a/uncrypt/uncrypt.cpp b/uncrypt/uncrypt.cpp new file mode 100644 index 000000000..1db3013c6 --- /dev/null +++ b/uncrypt/uncrypt.cpp @@ -0,0 +1,465 @@ +/* + * 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/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"); + sleep(10); + 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; +} |