1 files changed, 377 insertions, 0 deletions

diff --git a/uncrypt/uncrypt.c b/uncrypt/uncrypt.c
new file mode 100644
index 000000000..1f0f59dba
--- /dev/null
+++ b/uncrypt/uncrypt.c
@@ -0,0 +1,377 @@
+/*
+ * 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;
+}