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
15 unsigned long initrd_start, initrd_end;
16 int initrd_below_start_ok;
17 static unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
18 static int __initdata mount_initrd = 1;
19
20 phys_addr_t phys_initrd_start __initdata;
21 unsigned long phys_initrd_size __initdata;
22
23 #ifdef CONFIG_SYSCTL
24 static 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
kernel_do_mounts_initrd_sysctls_init(void)35 static __init int kernel_do_mounts_initrd_sysctls_init(void)
36 {
37 register_sysctl_init("kernel", kern_do_mounts_initrd_table);
38 return 0;
39 }
40 late_initcall(kernel_do_mounts_initrd_sysctls_init);
41 #endif /* CONFIG_SYSCTL */
42
no_initrd(char * str)43 static int __init no_initrd(char *str)
44 {
45 mount_initrd = 0;
46 return 1;
47 }
48
49 __setup("noinitrd", no_initrd);
50
early_initrdmem(char * p)51 static 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 }
66 early_param("initrdmem", early_initrdmem);
67
early_initrd(char * p)68 static int __init early_initrd(char *p)
69 {
70 return early_initrdmem(p);
71 }
72 early_param("initrd", early_initrd);
73
init_linuxrc(struct subprocess_info * info,struct cred * new)74 static 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
handle_initrd(char * root_device_name)86 static 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
initrd_load(char * root_device_name)137 bool __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