1// SPDX-License-Identifier: GPL-2.0
2/*
3 * /proc/bootconfig - Extra boot configuration
4 */
5#include <linux/fs.h>
6#include <linux/init.h>
7#include <linux/printk.h>
8#include <linux/proc_fs.h>
9#include <linux/seq_file.h>
10#include <linux/bootconfig.h>
11#include <linux/slab.h>
12
13static char *saved_boot_config;
14
15static int boot_config_proc_show(struct seq_file *m, void *v)
16{
17	if (saved_boot_config)
18		seq_puts(m, saved_boot_config);
19	return 0;
20}
21
22/* Rest size of buffer */
23#define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
24
25/* Return the needed total length if @size is 0 */
26static int __init copy_xbc_key_value_list(char *dst, size_t size)
27{
28	struct xbc_node *leaf, *vnode;
29	char *key, *end = dst + size;
30	const char *val;
31	char q;
32	int ret = 0;
33
34	key = kzalloc(XBC_KEYLEN_MAX, GFP_KERNEL);
35	if (!key)
36		return -ENOMEM;
37
38	xbc_for_each_key_value(leaf, val) {
39		ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX);
40		if (ret < 0)
41			break;
42		ret = snprintf(dst, rest(dst, end), "%s = ", key);
43		if (ret < 0)
44			break;
45		dst += ret;
46		vnode = xbc_node_get_child(leaf);
47		if (vnode) {
48			xbc_array_for_each_value(vnode, val) {
49				if (strchr(val, '"'))
50					q = '\'';
51				else
52					q = '"';
53				ret = snprintf(dst, rest(dst, end), "%c%s%c%s",
54					q, val, q, xbc_node_is_array(vnode) ? ", " : "\n");
55				if (ret < 0)
56					goto out;
57				dst += ret;
58			}
59		} else {
60			ret = snprintf(dst, rest(dst, end), "\"\"\n");
61			if (ret < 0)
62				break;
63			dst += ret;
64		}
65	}
66	if (cmdline_has_extra_options() && ret >= 0 && boot_command_line[0]) {
67		ret = snprintf(dst, rest(dst, end), "# Parameters from bootloader:\n# %s\n",
68			       boot_command_line);
69		if (ret > 0)
70			dst += ret;
71	}
72out:
73	kfree(key);
74
75	return ret < 0 ? ret : dst - (end - size);
76}
77
78static int __init proc_boot_config_init(void)
79{
80	int len;
81
82	len = copy_xbc_key_value_list(NULL, 0);
83	if (len < 0)
84		return len;
85
86	if (len > 0) {
87		saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
88		if (!saved_boot_config)
89			return -ENOMEM;
90
91		len = copy_xbc_key_value_list(saved_boot_config, len + 1);
92		if (len < 0) {
93			kfree(saved_boot_config);
94			return len;
95		}
96	}
97
98	proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
99
100	return 0;
101}
102fs_initcall(proc_boot_config_init);
103