/*
* Copyright (C) 2008 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.
*/
#include <errno.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include "mincrypt/sha.h"
#include "applypatch.h"
#include "mtdutils/mtdutils.h"
#include "edify/expr.h"
int SaveFileContents(const char* filename, FileContents file);
int LoadMTDContents(const char* filename, FileContents* file);
int ParseSha1(const char* str, uint8_t* digest);
ssize_t FileSink(unsigned char* data, ssize_t len, void* token);
static int mtd_partitions_scanned = 0;
// Read a file into memory; store it and its associated metadata in
// *file. Return 0 on success.
int LoadFileContents(const char* filename, FileContents* file) {
file->data = NULL;
// A special 'filename' beginning with "MTD:" means to load the
// contents of an MTD partition.
if (strncmp(filename, "MTD:", 4) == 0) {
return LoadMTDContents(filename, file);
}
if (stat(filename, &file->st) != 0) {
printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
return -1;
}
file->size = file->st.st_size;
file->data = malloc(file->size);
FILE* f = fopen(filename, "rb");
if (f == NULL) {
printf("failed to open \"%s\": %s\n", filename, strerror(errno));
free(file->data);
file->data = NULL;
return -1;
}
ssize_t bytes_read = fread(file->data, 1, file->size, f);
if (bytes_read != file->size) {
printf("short read of \"%s\" (%ld bytes of %ld)\n",
filename, (long)bytes_read, (long)file->size);
free(file->data);
file->data = NULL;
return -1;
}
fclose(f);
SHA(file->data, file->size, file->sha1);
return 0;
}
static size_t* size_array;
// comparison function for qsort()ing an int array of indexes into
// size_array[].
static int compare_size_indices(const void* a, const void* b) {
int aa = *(int*)a;
int bb = *(int*)b;
if (size_array[aa] < size_array[bb]) {
return -1;
} else if (size_array[aa] > size_array[bb]) {
return 1;
} else {
return 0;
}
}
void FreeFileContents(FileContents* file) {
if (file) free(file->data);
free(file);
}
// Load the contents of an MTD partition into the provided
// FileContents. filename should be a string of the form
// "MTD:<partition_name>:<size_1>:<sha1_1>:<size_2>:<sha1_2>:...".
// The smallest size_n bytes for which that prefix of the mtd contents
// has the corresponding sha1 hash will be loaded. It is acceptable
// for a size value to be repeated with different sha1s. Will return
// 0 on success.
//
// This complexity is needed because if an OTA installation is
// interrupted, the partition might contain either the source or the
// target data, which might be of different lengths. We need to know
// the length in order to read from MTD (there is no "end-of-file"
// marker), so the caller must specify the possible lengths and the
// hash of the data, and we'll do the load expecting to find one of
// those hashes.
int LoadMTDContents(const char* filename, FileContents* file) {
char* copy = strdup(filename);
const char* magic = strtok(copy, ":");
if (strcmp(magic, "MTD") != 0) {
printf("LoadMTDContents called with bad filename (%s)\n",
filename);
return -1;
}
const char* partition = strtok(NULL, ":");
int i;
int colons = 0;
for (i = 0; filename[i] != '\0'; ++i) {
if (filename[i] == ':') {
++colons;
}
}
if (colons < 3 || colons%2 == 0) {
printf("LoadMTDContents called with bad filename (%s)\n",
filename);
}
int pairs = (colons-1)/2; // # of (size,sha1) pairs in filename
int* index = malloc(pairs * sizeof(int));
size_t* size = malloc(pairs * sizeof(size_t));
char** sha1sum = malloc(pairs * sizeof(char*));
for (i = 0; i < pairs; ++i) {
const char* size_str = strtok(NULL, ":");
size[i] = strtol(size_str, NULL, 10);
if (size[i] == 0) {
printf("LoadMTDContents called with bad size (%s)\n", filename);
return -1;
}
sha1sum[i] = strtok(NULL, ":");
index[i] = i;
}
// sort the index[] array so it indexes the pairs in order of
// increasing size.
size_array = size;
qsort(index, pairs, sizeof(int), compare_size_indices);
if (!mtd_partitions_scanned) {
mtd_scan_partitions();
mtd_partitions_scanned = 1;
}
const MtdPartition* mtd = mtd_find_partition_by_name(partition);
if (mtd == NULL) {
printf("mtd partition \"%s\" not found (loading %s)\n",
partition, filename);
return -1;
}
MtdReadContext* ctx = mtd_read_partition(mtd);
if (ctx == NULL) {
printf("failed to initialize read of mtd partition \"%s\"\n",
partition);
return -1;
}
SHA_CTX sha_ctx;
SHA_init(&sha_ctx);
uint8_t parsed_sha[SHA_DIGEST_SIZE];
// allocate enough memory to hold the largest size.
file->data = malloc(size[index[pairs-1]]);
char* p = (char*)file->data;
file->size = 0; // # bytes read so far
for (i = 0; i < pairs; ++i) {
// Read enough additional bytes to get us up to the next size
// (again, we're trying the possibilities in order of increasing
// size).
size_t next = size[index[i]] - file->size;
size_t read = 0;
if (next > 0) {
read = mtd_read_data(ctx, p, next);
if (next != read) {
printf("short read (%d bytes of %d) for partition \"%s\"\n",
read, next, partition);
free(file->data);
file->data = NULL;
return -1;
}
SHA_update(&sha_ctx, p, read);
file->size += read;
}
// Duplicate the SHA context and finalize the duplicate so we can
// check it against this pair's expected hash.
SHA_CTX temp_ctx;
memcpy(&temp_ctx, &sha_ctx, sizeof(SHA_CTX));
const uint8_t* sha_so_far = SHA_final(&temp_ctx);
if (ParseSha1(sha1sum[index[i]], parsed_sha) != 0) {
printf("failed to parse sha1 %s in %s\n",
sha1sum[index[i]], filename);
free(file->data);
file->data = NULL;
return -1;
}
if (memcmp(sha_so_far, parsed_sha, SHA_DIGEST_SIZE) == 0) {
// we have a match. stop reading the partition; we'll return
// the data we've read so far.
printf("mtd read matched size %d sha %s\n",
size[index[i]], sha1sum[index[i]]);
break;
}
p += read;
}
mtd_read_close(ctx);
if (i == pairs) {
// Ran off the end of the list of (size,sha1) pairs without
// finding a match.
printf("contents of MTD partition \"%s\" didn't match %s\n",
partition, filename);
free(file->data);
file->data = NULL;
return -1;
}
const uint8_t* sha_final = SHA_final(&sha_ctx);
for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
file->sha1[i] = sha_final[i];
}
// Fake some stat() info.
file->st.st_mode = 0644;
file->st.st_uid = 0;
file->st.st_gid = 0;
free(copy);
free(index);
free(size);
free(sha1sum);
return 0;
}
// Save the contents of the given FileContents object under the given
// filename. Return 0 on success.
int SaveFileContents(const char* filename, FileContents file) {
int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
if (fd < 0) {
printf("failed to open \"%s\" for write: %s\n",
filename, strerror(errno));
return -1;
}
ssize_t bytes_written = FileSink(file.data, file.size, &fd);
if (bytes_written != file.size) {
printf("short write of \"%s\" (%ld bytes of %ld) (%s)\n",
filename, (long)bytes_written, (long)file.size,
strerror(errno));
close(fd);
return -1;
}
fsync(fd);
close(fd);
if (chmod(filename, file.st.st_mode) != 0) {
printf("chmod of \"%s\" failed: %s\n", filename, strerror(errno));
return -1;
}
if (chown(filename, file.st.st_uid, file.st.st_gid) != 0) {
printf("chown of \"%s\" failed: %s\n", filename, strerror(errno));
return -1;
}
return 0;
}
// Write a memory buffer to target_mtd partition, a string of the form
// "MTD:<partition>[:...]". Return 0 on success.
int WriteToMTDPartition(unsigned char* data, size_t len,
const char* target_mtd) {
char* partition = strchr(target_mtd, ':');
if (partition == NULL) {
printf("bad MTD target name \"%s\"\n", target_mtd);
return -1;
}
++partition;
// Trim off anything after a colon, eg "MTD:boot:blah:blah:blah...".
// We want just the partition name "boot".
partition = strdup(partition);
char* end = strchr(partition, ':');
if (end != NULL)
*end = '\0';
if (!mtd_partitions_scanned) {
mtd_scan_partitions();
mtd_partitions_scanned = 1;
}
const MtdPartition* mtd = mtd_find_partition_by_name(partition);
if (mtd == NULL) {
printf("mtd partition \"%s\" not found for writing\n", partition);
return -1;
}
MtdWriteContext* ctx = mtd_write_partition(mtd);
if (ctx == NULL) {
printf("failed to init mtd partition \"%s\" for writing\n",
partition);
return -1;
}
size_t written = mtd_write_data(ctx, (char*)data, len);
if (written != len) {
printf("only wrote %d of %d bytes to MTD %s\n",
written, len, partition);
mtd_write_close(ctx);
return -1;
}
if (mtd_erase_blocks(ctx, -1) < 0) {
printf("error finishing mtd write of %s\n", partition);
mtd_write_close(ctx);
return -1;
}
if (mtd_write_close(ctx)) {
printf("error closing mtd write of %s\n", partition);
return -1;
}
free(partition);
return 0;
}
// Take a string 'str' of 40 hex digits and parse it into the 20
// byte array 'digest'. 'str' may contain only the digest or be of
// the form "<digest>:<anything>". Return 0 on success, -1 on any
// error.
int ParseSha1(const char* str, uint8_t* digest) {
int i;
const char* ps = str;
uint8_t* pd = digest;
for (i = 0; i < SHA_DIGEST_SIZE * 2; ++i, ++ps) {
int digit;
if (*ps >= '0' && *ps <= '9') {
digit = *ps - '0';
} else if (*ps >= 'a' && *ps <= 'f') {
digit = *ps - 'a' + 10;
} else if (*ps >= 'A' && *ps <= 'F') {
digit = *ps - 'A' + 10;
} else {
return -1;
}
if (i % 2 == 0) {
*pd = digit << 4;
} else {
*pd |= digit;
++pd;
}
}
if (*ps != '\0') return -1;
return 0;
}
// Search an array of sha1 strings for one matching the given sha1.
// Return the index of the match on success, or -1 if no match is
// found.
int FindMatchingPatch(uint8_t* sha1, char** const patch_sha1_str,
int num_patches) {
int i;
uint8_t patch_sha1[SHA_DIGEST_SIZE];
for (i = 0; i < num_patches; ++i) {
if (ParseSha1(patch_sha1_str[i], patch_sha1) == 0 &&
memcmp(patch_sha1, sha1, SHA_DIGEST_SIZE) == 0) {
return i;
}
}
return -1;
}
// Returns 0 if the contents of the file (argv[2]) or the cached file
// match any of the sha1's on the command line (argv[3:]). Returns
// nonzero otherwise.
int applypatch_check(const char* filename,
int num_patches, char** const patch_sha1_str) {
FileContents file;
file.data = NULL;
// It's okay to specify no sha1s; the check will pass if the
// LoadFileContents is successful. (Useful for reading MTD
// partitions, where the filename encodes the sha1s; no need to
// check them twice.)
if (LoadFileContents(filename, &file) != 0 ||
(num_patches > 0 &&
FindMatchingPatch(file.sha1, patch_sha1_str, num_patches) < 0)) {
printf("file \"%s\" doesn't have any of expected "
"sha1 sums; checking cache\n", filename);
free(file.data);
// If the source file is missing or corrupted, it might be because
// we were killed in the middle of patching it. A copy of it
// should have been made in CACHE_TEMP_SOURCE. If that file
// exists and matches the sha1 we're looking for, the check still
// passes.
if (LoadFileContents(CACHE_TEMP_SOURCE, &file) != 0) {
printf("failed to load cache file\n");
return 1;
}
if (FindMatchingPatch(file.sha1, patch_sha1_str, num_patches) < 0) {
printf("cache bits don't match any sha1 for \"%s\"\n", filename);
free(file.data);
return 1;
}
}
free(file.data);
return 0;
}
int ShowLicenses() {
ShowBSDiffLicense();
return 0;
}
ssize_t FileSink(unsigned char* data, ssize_t len, void* token) {
int fd = *(int *)token;
ssize_t done = 0;
ssize_t wrote;
while (done < (ssize_t) len) {
wrote = write(fd, data+done, len-done);
if (wrote <= 0) {
printf("error writing %d bytes: %s\n", (int)(len-done), strerror(errno));
return done;
}
done += wrote;
}
return done;
}
typedef struct {
unsigned char* buffer;
ssize_t size;
ssize_t pos;
} MemorySinkInfo;
ssize_t MemorySink(unsigned char* data, ssize_t len, void* token) {
MemorySinkInfo* msi = (MemorySinkInfo*)token;
if (msi->size - msi->pos < len) {
return -1;
}
memcpy(msi->buffer + msi->pos, data, len);
msi->pos += len;
return len;
}
// Return the amount of free space (in bytes) on the filesystem
// containing filename. filename must exist. Return -1 on error.
size_t FreeSpaceForFile(const char* filename) {
struct statfs sf;
if (statfs(filename, &sf) != 0) {
printf("failed to statfs %s: %s\n", filename, strerror(errno));
return -1;
}
return sf.f_bsize * sf.f_bfree;
}
int CacheSizeCheck(size_t bytes) {
if (MakeFreeSpaceOnCache(bytes) < 0) {
printf("unable to make %ld bytes available on /cache\n", (long)bytes);
return 1;
} else {
return 0;
}
}
// This function applies binary patches to files in a way that is safe
// (the original file is not touched until we have the desired
// replacement for it) and idempotent (it's okay to run this program
// multiple times).
//
// - if the sha1 hash of <target_filename> is <target_sha1_string>,
// does nothing and exits successfully.
//
// - otherwise, if the sha1 hash of <source_filename> is one of the
// entries in <patch_sha1_str>, the corresponding patch from
// <patch_data> (which must be a VAL_BLOB) is applied to produce a
// new file (the type of patch is automatically detected from the
// blob daat). If that new file has sha1 hash <target_sha1_str>,
// moves it to replace <target_filename>, and exits successfully.
// Note that if <source_filename> and <target_filename> are not the
// same, <source_filename> is NOT deleted on success.
// <target_filename> may be the string "-" to mean "the same as
// source_filename".
//
// - otherwise, or if any error is encountered, exits with non-zero
// status.
//
// <source_filename> may refer to an MTD partition to read the source
// data. See the comments for the LoadMTDContents() function above
// for the format of such a filename.
int applypatch(const char* source_filename,
const char* target_filename,
const char* target_sha1_str,
size_t target_size,
int num_patches,
char** const patch_sha1_str,
Value** patch_data) {
printf("\napplying patch to %s\n", source_filename);
if (target_filename[0] == '-' &&
target_filename[1] == '\0') {
target_filename = source_filename;
}
uint8_t target_sha1[SHA_DIGEST_SIZE];
if (ParseSha1(target_sha1_str, target_sha1) != 0) {
printf("failed to parse tgt-sha1 \"%s\"\n", target_sha1_str);
return 1;
}
FileContents copy_file;
FileContents source_file;
const Value* source_patch_value = NULL;
const Value* copy_patch_value = NULL;
int made_copy = 0;
// We try to load the target file into the source_file object.
if (LoadFileContents(target_filename, &source_file) == 0) {
if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_SIZE) == 0) {
// The early-exit case: the patch was already applied, this file
// has the desired hash, nothing for us to do.
printf("\"%s\" is already target; no patch needed\n",
target_filename);
return 0;
}
}
if (source_file.data == NULL ||
(target_filename != source_filename &&
strcmp(target_filename, source_filename) != 0)) {
// Need to load the source file: either we failed to load the
// target file, or we did but it's different from the source file.
free(source_file.data);
LoadFileContents(source_filename, &source_file);
}
if (source_file.data != NULL) {
int to_use = FindMatchingPatch(source_file.sha1,
patch_sha1_str, num_patches);
if (to_use >= 0) {
source_patch_value = patch_data[to_use];
}
}
if (source_patch_value == NULL) {
free(source_file.data);
printf("source file is bad; trying copy\n");
if (LoadFileContents(CACHE_TEMP_SOURCE, ©_file) < 0) {
// fail.
printf("failed to read copy file\n");
return 1;
}
int to_use = FindMatchingPatch(copy_file.sha1,
patch_sha1_str, num_patches);
if (to_use >= 0) {
copy_patch_value = patch_data[to_use];
}
if (copy_patch_value == NULL) {
// fail.
printf("copy file doesn't match source SHA-1s either\n");
return 1;
}
}
int retry = 1;
SHA_CTX ctx;
int output;
MemorySinkInfo msi;
FileContents* source_to_use;
char* outname;
// assume that target_filename (eg "/system/app/Foo.apk") is located
// on the same filesystem as its top-level directory ("/system").
// We need something that exists for calling statfs().
char target_fs[strlen(target_filename)+1];
char* slash = strchr(target_filename+1, '/');
if (slash != NULL) {
int count = slash - target_filename;
strncpy(target_fs, target_filename, count);
target_fs[count] = '\0';
} else {
strcpy(target_fs, target_filename);
}
do {
// Is there enough room in the target filesystem to hold the patched
// file?
if (strncmp(target_filename, "MTD:", 4) == 0) {
// If the target is an MTD partition, we're actually going to
// write the output to /tmp and then copy it to the partition.
// statfs() always returns 0 blocks free for /tmp, so instead
// we'll just assume that /tmp has enough space to hold the file.
// We still write the original source to cache, in case the MTD
// write is interrupted.
if (MakeFreeSpaceOnCache(source_file.size) < 0) {
printf("not enough free space on /cache\n");
return 1;
}
if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
printf("failed to back up source file\n");
return 1;
}
made_copy = 1;
retry = 0;
} else {
int enough_space = 0;
if (retry > 0) {
size_t free_space = FreeSpaceForFile(target_fs);
enough_space =
(free_space > (256 << 10)) && // 256k (two-block) minimum
(free_space > (target_size * 3 / 2)); // 50% margin of error
printf("target %ld bytes; free space %ld bytes; retry %d; enough %d\n",
(long)target_size, (long)free_space, retry, enough_space);
}
if (!enough_space) {
retry = 0;
}
if (!enough_space && source_patch_value != NULL) {
// Using the original source, but not enough free space. First
// copy the source file to cache, then delete it from the original
// location.
if (strncmp(source_filename, "MTD:", 4) == 0) {
// It's impossible to free space on the target filesystem by
// deleting the source if the source is an MTD partition. If
// we're ever in a state where we need to do this, fail.
printf("not enough free space for target but source is MTD\n");
return 1;
}
if (MakeFreeSpaceOnCache(source_file.size) < 0) {
printf("not enough free space on /cache\n");
return 1;
}
if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
printf("failed to back up source file\n");
return 1;
}
made_copy = 1;
unlink(source_filename);
size_t free_space = FreeSpaceForFile(target_fs);
printf("(now %ld bytes free for target)\n", (long)free_space);
}
}
const Value* patch;
if (source_patch_value != NULL) {
source_to_use = &source_file;
patch = source_patch_value;
} else {
source_to_use = ©_file;
patch = copy_patch_value;
}
if (patch->type != VAL_BLOB) {
printf("patch is not a blob\n");
return 1;
}
SinkFn sink = NULL;
void* token = NULL;
output = -1;
outname = NULL;
if (strncmp(target_filename, "MTD:", 4) == 0) {
// We store the decoded output in memory.
msi.buffer = malloc(target_size);
if (msi.buffer == NULL) {
printf("failed to alloc %ld bytes for output\n",
(long)target_size);
return 1;
}
msi.pos = 0;
msi.size = target_size;
sink = MemorySink;
token = &msi;
} else {
// We write the decoded output to "<tgt-file>.patch".
outname = (char*)malloc(strlen(target_filename) + 10);
strcpy(outname, target_filename);
strcat(outname, ".patch");
output = open(outname, O_WRONLY | O_CREAT | O_TRUNC);
if (output < 0) {
printf("failed to open output file %s: %s\n",
outname, strerror(errno));
return 1;
}
sink = FileSink;
token = &output;
}
char* header = patch->data;
ssize_t header_bytes_read = patch->size;
SHA_init(&ctx);
int result;
if (header_bytes_read >= 8 &&
memcmp(header, "BSDIFF40", 8) == 0) {
result = ApplyBSDiffPatch(source_to_use->data, source_to_use->size,
patch, 0, sink, token, &ctx);
} else if (header_bytes_read >= 8 &&
memcmp(header, "IMGDIFF2", 8) == 0) {
result = ApplyImagePatch(source_to_use->data, source_to_use->size,
patch, sink, token, &ctx);
} else {
printf("Unknown patch file format\n");
return 1;
}
if (output >= 0) {
fsync(output);
close(output);
}
if (result != 0) {
if (retry == 0) {
printf("applying patch failed\n");
return result != 0;
} else {
printf("applying patch failed; retrying\n");
}
if (outname != NULL) {
unlink(outname);
}
} else {
// succeeded; no need to retry
break;
}
} while (retry-- > 0);
const uint8_t* current_target_sha1 = SHA_final(&ctx);
if (memcmp(current_target_sha1, target_sha1, SHA_DIGEST_SIZE) != 0) {
printf("patch did not produce expected sha1\n");
return 1;
}
if (output < 0) {
// Copy the temp file to the MTD partition.
if (WriteToMTDPartition(msi.buffer, msi.pos, target_filename) != 0) {
printf("write of patched data to %s failed\n", target_filename);
return 1;
}
free(msi.buffer);
} else {
// Give the .patch file the same owner, group, and mode of the
// original source file.
if (chmod(outname, source_to_use->st.st_mode) != 0) {
printf("chmod of \"%s\" failed: %s\n", outname, strerror(errno));
return 1;
}
if (chown(outname, source_to_use->st.st_uid,
source_to_use->st.st_gid) != 0) {
printf("chown of \"%s\" failed: %s\n", outname, strerror(errno));
return 1;
}
// Finally, rename the .patch file to replace the target file.
if (rename(outname, target_filename) != 0) {
printf("rename of .patch to \"%s\" failed: %s\n",
target_filename, strerror(errno));
return 1;
}
}
// If this run of applypatch created the copy, and we're here, we
// can delete it.
if (made_copy) unlink(CACHE_TEMP_SOURCE);
// Success!
return 0;
}
