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/* Copyright 2015 The ChromiumOS Authors
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* This utility wraps around "cgpt" execution to work with NAND. If the target
* device is an MTD device, this utility will read the GPT structures from
* FMAP, invokes "cgpt" on that, and writes the result back to NOR flash. */
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#if !defined(__FreeBSD__)
#include <linux/major.h>
#endif
#include <stdbool.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#if !defined(__FreeBSD__)
#include <sys/sysmacros.h>
#endif
#include <sys/types.h>
#include <unistd.h>
#include "2common.h"
#include "2sha.h"
#include "2sysincludes.h"
#include "cgpt.h"
#include "cgpt_nor.h"
#include "file_keys.h"
// Check if cmdline |argv| has "-D". "-D" signifies that GPT structs are stored
// off device, and hence we should not wrap around cgpt.
static bool has_dash_D(int argc, const char *const argv[]) {
int i;
// We go from 2, because the second arg is a cgpt command such as "create".
for (i = 2; i < argc; ++i) {
if (strcmp("-D", argv[i]) == 0) {
return true;
}
}
return false;
}
// Check if |device_path| is an MTD device based on its major number being 90.
static bool is_mtd(const char *device_path) {
struct stat stat;
if (lstat(device_path, &stat) != 0) {
return false;
}
#if !defined(__FreeBSD__)
if (major(stat.st_rdev) == MTD_CHAR_MAJOR) {
return true;
}
#endif
return false;
}
// Return the element in |argv| that is an MTD device.
static const char *find_mtd_device(int argc, const char *const argv[]) {
int i;
for (i = 2; i < argc; ++i) {
if (is_mtd(argv[i])) {
return argv[i];
}
}
return NULL;
}
static int wrap_cgpt(int argc,
const char *const argv[],
const char *mtd_device) {
uint8_t original_hash[VB2_SHA1_DIGEST_SIZE];
uint8_t modified_hash[VB2_SHA1_DIGEST_SIZE];
int ret = 0;
// Create a temp dir to work in.
ret++;
char temp_dir[] = VBOOT_TMP_DIR "/cgpt_wrapper.XXXXXX";
if (mkdtemp(temp_dir_template) == NULL) {
Error("Cannot create a temporary directory.\n");
return ret;
}
if (ReadNorFlash(temp_dir) != 0) {
goto cleanup;
}
char rw_gpt_path[PATH_MAX];
if (snprintf(rw_gpt_path, sizeof(rw_gpt_path), "%s/rw_gpt", temp_dir) < 0) {
goto cleanup;
}
if (VB2_SUCCESS != DigestFile(rw_gpt_path, VB2_HASH_SHA1,
original_hash, sizeof(original_hash))) {
Error("Cannot compute original GPT digest.\n");
goto cleanup;
}
// Obtain the MTD size.
ret++;
uint64_t drive_size = 0;
if (GetMtdSize(mtd_device, &drive_size) != 0) {
Error("Cannot get the size of %s.\n", mtd_device);
goto cleanup;
}
// Launch cgpt on "rw_gpt" with -D size.
ret++;
const char** my_argv = calloc(argc + 2 + 1, sizeof(char *));
if (my_argv == NULL) {
errno = ENOMEM;
goto cleanup;
}
memcpy(my_argv, argv, sizeof(char *) * argc);
char *real_cgpt;
if (asprintf(&real_cgpt, "%s.bin", argv[0]) == -1) {
free(my_argv);
goto cleanup;
}
my_argv[0] = real_cgpt;
int i;
for (i = 2; i < argc; ++i) {
if (strcmp(my_argv[i], mtd_device) == 0) {
my_argv[i] = rw_gpt_path;
}
}
my_argv[argc] = "-D";
char size[32];
snprintf(size, sizeof(size), "%" PRIu64, drive_size);
my_argv[argc + 1] = size;
i = ForkExecV(NULL, my_argv);
free(real_cgpt);
free(my_argv);
if (i != 0) {
Error("Cannot exec cgpt to modify rw_gpt.\n");
goto cleanup;
}
// Write back "rw_gpt" to NOR flash in two chunks.
ret++;
if (VB2_SUCCESS == DigestFile(rw_gpt_path, VB2_HASH_SHA1,
modified_hash, sizeof(modified_hash))) {
if (memcmp(original_hash, modified_hash, VB2_SHA1_DIGEST_SIZE) != 0) {
ret = WriteNorFlash(temp_dir);
} else {
ret = 0;
}
}
cleanup:
RemoveDir(temp_dir);
return ret;
}
int main(int argc, const char *argv[]) {
char resolved_cgpt[PATH_MAX];
pid_t pid = getpid();
char exe_link[40];
int retval = 0;
if (argc < 1) {
return -1;
}
const char *orig_argv0 = argv[0];
snprintf(exe_link, sizeof(exe_link), "/proc/%d/exe", pid);
memset(resolved_cgpt, 0, sizeof(resolved_cgpt));
if (readlink(exe_link, resolved_cgpt, sizeof(resolved_cgpt) - 1) == -1) {
perror("readlink");
return -1;
}
argv[0] = resolved_cgpt;
if (argc > 2 && !has_dash_D(argc, argv)) {
const char *mtd_device = find_mtd_device(argc, argv);
if (mtd_device) {
retval = wrap_cgpt(argc, argv, mtd_device);
goto cleanup;
}
}
// Forward to cgpt as-is. Real cgpt has been renamed cgpt.bin.
char *real_cgpt;
if (asprintf(&real_cgpt, "%s.bin", argv[0]) == -1) {
retval = -1;
goto cleanup;
}
argv[0] = real_cgpt;
if (execv(argv[0], (char * const *)argv) == -1) {
err(-2, "execv(%s) failed", real_cgpt);
}
free(real_cgpt);
retval = -2;
cleanup:
argv[0] = orig_argv0;
return retval;
}
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