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-rw-r--r--uncrypt/uncrypt.c377
1 files changed, 377 insertions, 0 deletions
diff --git a/uncrypt/uncrypt.c b/uncrypt/uncrypt.c
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--- /dev/null
+++ b/uncrypt/uncrypt.c
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+/*
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <linux/fs.h>
+#include <sys/mman.h>
+
+#include <cutils/properties.h>
+#include <fs_mgr.h>
+
+#define WINDOW_SIZE 5
+#define RECOVERY_COMMAND_FILE "/cache/recovery/command"
+#define RECOVERY_COMMAND_FILE_TMP "/cache/recovery/command.tmp"
+#define CACHE_BLOCK_MAP "/cache/recovery/block.map"
+
+static int write_at_offset(unsigned char* buffer, size_t size,
+ int wfd, off64_t offset)
+{
+ lseek64(wfd, offset, SEEK_SET);
+ size_t written = 0;
+ while (written < size) {
+ ssize_t wrote = write(wfd, buffer + written, size - written);
+ if (wrote < 0) {
+ fprintf(stderr, "error writing offset %lld: %s\n", offset, strerror(errno));
+ return -1;
+ }
+ written += wrote;
+ }
+ return 0;
+}
+
+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 = realloc(*ranges, *range_alloc * 2 * sizeof(int));
+ }
+
+ ++*range_used;
+ (*ranges)[*range_used*2-2] = new_block;
+ (*ranges)[*range_used*2-1] = new_block+1;
+ }
+}
+
+const char* find_block_device(const char* path, int* encryptable, int* encrypted)
+{
+ // 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), "")) {
+ fprintf(stderr, "failed to get ro.hardware\n");
+ return NULL;
+ }
+
+ struct fstab* fstab = fs_mgr_read_fstab(fstab_path);
+ if (!fstab) {
+ fprintf(stderr, "failed to read %s\n", fstab_path);
+ return NULL;
+ }
+
+ // Look for a volume whose mount point is the prefix of path and
+ // return its block device. Set encrypted if it's currently
+ // encrypted.
+ int i;
+ for (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 = 0;
+ *encryptable = 0;
+ if (fs_mgr_is_encryptable(v)) {
+ *encryptable = 1;
+ char buffer[PROPERTY_VALUE_MAX+1];
+ if (property_get("ro.crypto.state", buffer, "") &&
+ strcmp(buffer, "encrypted") == 0) {
+ *encrypted = 1;
+ }
+ }
+ return v->blk_device;
+ }
+ }
+
+ return NULL;
+}
+
+char* parse_recovery_command_file()
+{
+ char* fn = NULL;
+ int count = 0;
+ char temp[1024];
+
+ FILE* fo = fopen(RECOVERY_COMMAND_FILE_TMP, "w");
+
+ FILE* f = fopen(RECOVERY_COMMAND_FILE, "r");
+ while (fgets(temp, sizeof(temp), f)) {
+ printf("read: %s", temp);
+ if (strncmp(temp, "--update_package=", strlen("--update_package=")) == 0) {
+ fn = strdup(temp + strlen("--update_package="));
+ strcpy(temp, "--update_package=@" CACHE_BLOCK_MAP "\n");
+ }
+ fputs(temp, fo);
+ }
+ fclose(f);
+ fclose(fo);
+
+ if (fn) {
+ char* newline = strchr(fn, '\n');
+ if (newline) *newline = 0;
+ }
+ return fn;
+}
+
+int produce_block_map(const char* path, const char* map_file, const char* blk_dev,
+ int encrypted)
+{
+ struct stat sb;
+ int ret;
+
+ FILE* mapf = fopen(map_file, "w");
+
+ ret = stat(path, &sb);
+ if (ret != 0) {
+ fprintf(stderr, "failed to stat %s\n", path);
+ return -1;
+ }
+
+ printf(" block size: %ld bytes\n", sb.st_blksize);
+
+ int blocks = ((sb.st_size-1) / sb.st_blksize) + 1;
+ printf(" file size: %lld bytes, %d blocks\n", sb.st_size, blocks);
+
+ int* ranges;
+ int range_alloc = 1;
+ int range_used = 1;
+ ranges = malloc(range_alloc * 2 * sizeof(int));
+ ranges[0] = -1;
+ ranges[1] = -1;
+
+ fprintf(mapf, "%s\n%lld %lu\n", blk_dev, sb.st_size, sb.st_blksize);
+
+ unsigned char* buffers[WINDOW_SIZE];
+ int i;
+ if (encrypted) {
+ for (i = 0; i < WINDOW_SIZE; ++i) {
+ buffers[i] = 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) {
+ fprintf(stderr, "failed to open fd for reading: %s\n", strerror(errno));
+ return -1;
+ }
+ fsync(fd);
+
+ int wfd = -1;
+ if (encrypted) {
+ wfd = open(blk_dev, O_WRONLY);
+ if (wfd < 0) {
+ fprintf(stderr, "failed to open fd for writing: %s\n", strerror(errno));
+ return -1;
+ }
+ }
+
+ while (pos < sb.st_size) {
+ if ((tail+1) % WINDOW_SIZE == head) {
+ // write out head buffer
+ int block = head_block;
+ ret = ioctl(fd, FIBMAP, &block);
+ if (ret != 0) {
+ fprintf(stderr, "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 = read(fd, buffers[tail] + so_far, sb.st_blksize - so_far);
+ if (this_read < 0) {
+ fprintf(stderr, "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) {
+ fprintf(stderr, "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 (i = 0; i < range_used; ++i) {
+ fprintf(mapf, "%d %d\n", ranges[i*2], ranges[i*2+1]);
+ }
+
+ fclose(mapf);
+ close(fd);
+ if (encrypted) {
+ close(wfd);
+ }
+
+ return 0;
+}
+
+void reboot_to_recovery() {
+ property_set("sys.powerctl", "reboot,recovery");
+ sleep(10);
+}
+
+int main(int argc, char** argv)
+{
+ const char* input_path;
+ const char* map_file;
+ int do_reboot = 1;
+
+ if (argc != 1 && argc != 3) {
+ fprintf(stderr, "usage: %s [<transform_path> <map_file>]\n", argv[0]);
+ return 2;
+ }
+
+ if (argc == 3) {
+ // when command-line args are given this binary is being used
+ // for debugging; don't reboot to recovery at the end.
+ input_path = argv[1];
+ map_file = argv[2];
+ do_reboot = 0;
+ } else {
+ input_path = parse_recovery_command_file();
+ if (input_path == NULL) {
+ // if we're rebooting to recovery without a package (say,
+ // to wipe data), then we don't need to do anything before
+ // going to recovery.
+ fprintf(stderr, "no recovery command file or no update package arg");
+ reboot_to_recovery();
+ return 1;
+ }
+ map_file = CACHE_BLOCK_MAP;
+ }
+
+ // 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) {
+ fprintf(stderr, "failed to convert %s to absolute path: %s\n", input_path, strerror(errno));
+ return 1;
+ }
+
+ int encryptable;
+ int encrypted;
+ const char* blk_dev = find_block_device(path, &encryptable, &encrypted);
+ if (blk_dev == NULL) {
+ fprintf(stderr, "failed to find block device for %s\n", 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).
+ printf("encryptable: %s\n", encryptable ? "yes" : "no");
+ printf(" encrypted: %s\n", encrypted ? "yes" : "no");
+
+ if (!encryptable) {
+ // If the file is on a filesystem that doesn't support
+ // encryption (eg, /cache), then leave it alone.
+ //
+ // TODO: change this to be !encrypted -- if the file is on
+ // /data but /data isn't encrypted, we don't need to use the
+ // block map mechanism. We do for now so as to get more
+ // testing of it (since most dogfood devices aren't
+ // encrypted).
+
+ unlink(RECOVERY_COMMAND_FILE_TMP);
+ } else {
+ if (produce_block_map(path, map_file, blk_dev, encrypted) != 0) {
+ return 1;
+ }
+ }
+
+ rename(RECOVERY_COMMAND_FILE_TMP, RECOVERY_COMMAND_FILE);
+ reboot_to_recovery();
+ return 0;
+}