linux/tools/bootconfig/main.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Boot config tool for initrd image
 */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include <linux/kernel.h>
#include <linux/bootconfig.h>

int pr_output = 1;

static int xbc_show_array(struct xbc_node *node)
{
	const char *val;
	int i = 0;

	xbc_array_for_each_value(node, val) {
		printf("\"%s\"%s", val, node->next ? ", " : ";\n");
		i++;
	}
	return i;
}

static void xbc_show_compact_tree(void)
{
	struct xbc_node *node, *cnode;
	int depth = 0, i;

	node = xbc_root_node();
	while (node && xbc_node_is_key(node)) {
		for (i = 0; i < depth; i++)
			printf("\t");
		cnode = xbc_node_get_child(node);
		while (cnode && xbc_node_is_key(cnode) && !cnode->next) {
			printf("%s.", xbc_node_get_data(node));
			node = cnode;
			cnode = xbc_node_get_child(node);
		}
		if (cnode && xbc_node_is_key(cnode)) {
			printf("%s {\n", xbc_node_get_data(node));
			depth++;
			node = cnode;
			continue;
		} else if (cnode && xbc_node_is_value(cnode)) {
			printf("%s = ", xbc_node_get_data(node));
			if (cnode->next)
				xbc_show_array(cnode);
			else
				printf("\"%s\";\n", xbc_node_get_data(cnode));
		} else {
			printf("%s;\n", xbc_node_get_data(node));
		}

		if (node->next) {
			node = xbc_node_get_next(node);
			continue;
		}
		while (!node->next) {
			node = xbc_node_get_parent(node);
			if (!node)
				return;
			if (!xbc_node_get_child(node)->next)
				continue;
			depth--;
			for (i = 0; i < depth; i++)
				printf("\t");
			printf("}\n");
		}
		node = xbc_node_get_next(node);
	}
}

/* Simple real checksum */
int checksum(unsigned char *buf, int len)
{
	int i, sum = 0;

	for (i = 0; i < len; i++)
		sum += buf[i];

	return sum;
}

#define PAGE_SIZE	4096

int load_xbc_fd(int fd, char **buf, int size)
{
	int ret;

	*buf = malloc(size + 1);
	if (!*buf)
		return -ENOMEM;

	ret = read(fd, *buf, size);
	if (ret < 0)
		return -errno;
	(*buf)[size] = '\0';

	return ret;
}

/* Return the read size or -errno */
int load_xbc_file(const char *path, char **buf)
{
	struct stat stat;
	int fd, ret;

	fd = open(path, O_RDONLY);
	if (fd < 0)
		return -errno;
	ret = fstat(fd, &stat);
	if (ret < 0)
		return -errno;

	ret = load_xbc_fd(fd, buf, stat.st_size);

	close(fd);

	return ret;
}

int load_xbc_from_initrd(int fd, char **buf)
{
	struct stat stat;
	int ret;
	u32 size = 0, csum = 0, rcsum;
	char magic[BOOTCONFIG_MAGIC_LEN];

	ret = fstat(fd, &stat);
	if (ret < 0)
		return -errno;

	if (stat.st_size < 8 + BOOTCONFIG_MAGIC_LEN)
		return 0;

	if (lseek(fd, -BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0) {
		pr_err("Failed to lseek: %d\n", -errno);
		return -errno;
	}
	if (read(fd, magic, BOOTCONFIG_MAGIC_LEN) < 0)
		return -errno;
	/* Check the bootconfig magic bytes */
	if (memcmp(magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN) != 0)
		return 0;

	if (lseek(fd, -(8 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0) {
		pr_err("Failed to lseek: %d\n", -errno);
		return -errno;
	}

	if (read(fd, &size, sizeof(u32)) < 0)
		return -errno;

	if (read(fd, &csum, sizeof(u32)) < 0)
		return -errno;

	/* Wrong size error  */
	if (stat.st_size < size + 8 + BOOTCONFIG_MAGIC_LEN) {
		pr_err("bootconfig size is too big\n");
		return -E2BIG;
	}

	if (lseek(fd, stat.st_size - (size + 8 + BOOTCONFIG_MAGIC_LEN),
		  SEEK_SET) < 0) {
		pr_err("Failed to lseek: %d\n", -errno);
		return -errno;
	}

	ret = load_xbc_fd(fd, buf, size);
	if (ret < 0)
		return ret;

	/* Wrong Checksum */
	rcsum = checksum((unsigned char *)*buf, size);
	if (csum != rcsum) {
		pr_err("checksum error: %d != %d\n", csum, rcsum);
		return -EINVAL;
	}

	ret = xbc_init(*buf);
	/* Wrong data */
	if (ret < 0)
		return ret;

	return size;
}

int show_xbc(const char *path)
{
	int ret, fd;
	char *buf = NULL;

	fd = open(path, O_RDONLY);
	if (fd < 0) {
		pr_err("Failed to open initrd %s: %d\n", path, fd);
		return -errno;
	}

	ret = load_xbc_from_initrd(fd, &buf);
	if (ret < 0)
		pr_err("Failed to load a boot config from initrd: %d\n", ret);
	else
		xbc_show_compact_tree();

	close(fd);
	free(buf);

	return ret;
}

int delete_xbc(const char *path)
{
	struct stat stat;
	int ret = 0, fd, size;
	char *buf = NULL;

	fd = open(path, O_RDWR);
	if (fd < 0) {
		pr_err("Failed to open initrd %s: %d\n", path, fd);
		return -errno;
	}

	/*
	 * Suppress error messages in xbc_init() because it can be just a
	 * data which concidentally matches the size and checksum footer.
	 */
	pr_output = 0;
	size = load_xbc_from_initrd(fd, &buf);
	pr_output = 1;
	if (size < 0) {
		ret = size;
		pr_err("Failed to load a boot config from initrd: %d\n", ret);
	} else if (size > 0) {
		ret = fstat(fd, &stat);
		if (!ret)
			ret = ftruncate(fd, stat.st_size
					- size - 8 - BOOTCONFIG_MAGIC_LEN);
		if (ret)
			ret = -errno;
	} /* Ignore if there is no boot config in initrd */

	close(fd);
	free(buf);

	return ret;
}

int apply_xbc(const char *path, const char *xbc_path)
{
	u32 size, csum;
	char *buf, *data;
	int ret, fd;

	ret = load_xbc_file(xbc_path, &buf);
	if (ret < 0) {
		pr_err("Failed to load %s : %d\n", xbc_path, ret);
		return ret;
	}
	size = strlen(buf) + 1;
	csum = checksum((unsigned char *)buf, size);

	/* Prepare xbc_path data */
	data = malloc(size + 8);
	if (!data)
		return -ENOMEM;
	strcpy(data, buf);
	*(u32 *)(data + size) = size;
	*(u32 *)(data + size + 4) = csum;

	/* Check the data format */
	ret = xbc_init(buf);
	if (ret < 0) {
		pr_err("Failed to parse %s: %d\n", xbc_path, ret);
		free(data);
		free(buf);
		return ret;
	}
	printf("Apply %s to %s\n", xbc_path, path);
	printf("\tNumber of nodes: %d\n", ret);
	printf("\tSize: %u bytes\n", (unsigned int)size);
	printf("\tChecksum: %d\n", (unsigned int)csum);

	/* TODO: Check the options by schema */
	xbc_destroy_all();
	free(buf);

	/* Remove old boot config if exists */
	ret = delete_xbc(path);
	if (ret < 0) {
		pr_err("Failed to delete previous boot config: %d\n", ret);
		return ret;
	}

	/* Apply new one */
	fd = open(path, O_RDWR | O_APPEND);
	if (fd < 0) {
		pr_err("Failed to open %s: %d\n", path, fd);
		return fd;
	}
	/* TODO: Ensure the @path is initramfs/initrd image */
	ret = write(fd, data, size + 8);
	if (ret < 0) {
		pr_err("Failed to apply a boot config: %d\n", ret);
		return ret;
	}
	/* Write a magic word of the bootconfig */
	ret = write(fd, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
	if (ret < 0) {
		pr_err("Failed to apply a boot config magic: %d\n", ret);
		return ret;
	}
	close(fd);
	free(data);

	return 0;
}

int usage(void)
{
	printf("Usage: bootconfig [OPTIONS] <INITRD>\n"
		" Apply, delete or show boot config to initrd.\n"
		" Options:\n"
		"		-a <config>: Apply boot config to initrd\n"
		"		-d : Delete boot config file from initrd\n\n"
		" If no option is given, show current applied boot config.\n");
	return -1;
}

int main(int argc, char **argv)
{
	char *path = NULL;
	char *apply = NULL;
	bool delete = false;
	int opt;

	while ((opt = getopt(argc, argv, "hda:")) != -1) {
		switch (opt) {
		case 'd':
			delete = true;
			break;
		case 'a':
			apply = optarg;
			break;
		case 'h':
		default:
			return usage();
		}
	}

	if (apply && delete) {
		pr_err("Error: You can not specify both -a and -d at once.\n");
		return usage();
	}

	if (optind >= argc) {
		pr_err("Error: No initrd is specified.\n");
		return usage();
	}

	path = argv[optind];

	if (apply)
		return apply_xbc(path, apply);
	else if (delete)
		return delete_xbc(path);

	return show_xbc(path);
}