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