1// SPDX-License-Identifier: GPL-2.0
2#include <linux/unistd.h>
3#include <linux/kernel.h>
4#include <linux/fs.h>
5#include <linux/minix_fs.h>
6#include <linux/romfs_fs.h>
7#include <linux/initrd.h>
8#include <linux/sched.h>
9#include <linux/freezer.h>
10#include <linux/kmod.h>
11#include <uapi/linux/mount.h>
12
13#include "do_mounts.h"
14
15unsigned long initrd_start, initrd_end;
16int initrd_below_start_ok;
17static unsigned int real_root_dev;	/* do_proc_dointvec cannot handle kdev_t */
18static int __initdata mount_initrd = 1;
19
20phys_addr_t phys_initrd_start __initdata;
21unsigned long phys_initrd_size __initdata;
22
23#ifdef CONFIG_SYSCTL
24static struct ctl_table kern_do_mounts_initrd_table[] = {
25	{
26		.procname       = "real-root-dev",
27		.data           = &real_root_dev,
28		.maxlen         = sizeof(int),
29		.mode           = 0644,
30		.proc_handler   = proc_dointvec,
31	},
32	{ }
33};
34
35static __init int kernel_do_mounts_initrd_sysctls_init(void)
36{
37	register_sysctl_init("kernel", kern_do_mounts_initrd_table);
38	return 0;
39}
40late_initcall(kernel_do_mounts_initrd_sysctls_init);
41#endif /* CONFIG_SYSCTL */
42
43static int __init no_initrd(char *str)
44{
45	mount_initrd = 0;
46	return 1;
47}
48
49__setup("noinitrd", no_initrd);
50
51static int __init early_initrdmem(char *p)
52{
53	phys_addr_t start;
54	unsigned long size;
55	char *endp;
56
57	start = memparse(p, &endp);
58	if (*endp == ',') {
59		size = memparse(endp + 1, NULL);
60
61		phys_initrd_start = start;
62		phys_initrd_size = size;
63	}
64	return 0;
65}
66early_param("initrdmem", early_initrdmem);
67
68static int __init early_initrd(char *p)
69{
70	return early_initrdmem(p);
71}
72early_param("initrd", early_initrd);
73
74static int __init init_linuxrc(struct subprocess_info *info, struct cred *new)
75{
76	ksys_unshare(CLONE_FS | CLONE_FILES);
77	console_on_rootfs();
78	/* move initrd over / and chdir/chroot in initrd root */
79	init_chdir("/root");
80	init_mount(".", "/", NULL, MS_MOVE, NULL);
81	init_chroot(".");
82	ksys_setsid();
83	return 0;
84}
85
86static void __init handle_initrd(char *root_device_name)
87{
88	struct subprocess_info *info;
89	static char *argv[] = { "linuxrc", NULL, };
90	extern char *envp_init[];
91	int error;
92
93	pr_warn("using deprecated initrd support, will be removed in 2021.\n");
94
95	real_root_dev = new_encode_dev(ROOT_DEV);
96	create_dev("/dev/root.old", Root_RAM0);
97	/* mount initrd on rootfs' /root */
98	mount_root_generic("/dev/root.old", root_device_name,
99			   root_mountflags & ~MS_RDONLY);
100	init_mkdir("/old", 0700);
101	init_chdir("/old");
102
103	info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
104					 GFP_KERNEL, init_linuxrc, NULL, NULL);
105	if (!info)
106		return;
107	call_usermodehelper_exec(info, UMH_WAIT_PROC|UMH_FREEZABLE);
108
109	/* move initrd to rootfs' /old */
110	init_mount("..", ".", NULL, MS_MOVE, NULL);
111	/* switch root and cwd back to / of rootfs */
112	init_chroot("..");
113
114	if (new_decode_dev(real_root_dev) == Root_RAM0) {
115		init_chdir("/old");
116		return;
117	}
118
119	init_chdir("/");
120	ROOT_DEV = new_decode_dev(real_root_dev);
121	mount_root(root_device_name);
122
123	printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
124	error = init_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
125	if (!error)
126		printk("okay\n");
127	else {
128		if (error == -ENOENT)
129			printk("/initrd does not exist. Ignored.\n");
130		else
131			printk("failed\n");
132		printk(KERN_NOTICE "Unmounting old root\n");
133		init_umount("/old", MNT_DETACH);
134	}
135}
136
137bool __init initrd_load(char *root_device_name)
138{
139	if (mount_initrd) {
140		create_dev("/dev/ram", Root_RAM0);
141		/*
142		 * Load the initrd data into /dev/ram0. Execute it as initrd
143		 * unless /dev/ram0 is supposed to be our actual root device,
144		 * in that case the ram disk is just set up here, and gets
145		 * mounted in the normal path.
146		 */
147		if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
148			init_unlink("/initrd.image");
149			handle_initrd(root_device_name);
150			return true;
151		}
152	}
153	init_unlink("/initrd.image");
154	return false;
155}
156