init/do_mounts_initrd.c

   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
  12 #include "do_mounts.h"
  13
  14 unsigned long initrd_start, initrd_end;
  15 int initrd_below_start_ok;
  16 unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  17 static int __initdata mount_initrd = 1;
  18
  19 static int __init no_initrd(char *str)
  20 {
  21         mount_initrd = 0;
  22         return 1;
  23 }
  24
  25 __setup("noinitrd", no_initrd);
  26
  27 static int init_linuxrc(struct subprocess_info *info, struct cred *new)
  28 {
  29         ksys_unshare(CLONE_FS | CLONE_FILES);
  30         /* stdin/stdout/stderr for /linuxrc */
  31         ksys_open("/dev/console", O_RDWR, 0);
  32         ksys_dup(0);
  33         ksys_dup(0);
  34         /* move initrd over / and chdir/chroot in initrd root */
  35         ksys_chdir("/root");
  36         ksys_mount(".", "/", NULL, MS_MOVE, NULL);
  37         ksys_chroot(".");
  38         ksys_setsid();
  39         return 0;
  40 }
  41
  42 static void __init handle_initrd(void)
  43 {
  44         struct subprocess_info *info;
  45         static char *argv[] = { "linuxrc", NULL, };
  46         extern char *envp_init[];
  47         int error;
  48
  49         real_root_dev = new_encode_dev(ROOT_DEV);
  50         create_dev("/dev/root.old", Root_RAM0);
  51         /* mount initrd on rootfs' /root */
  52         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  53         ksys_mkdir("/old", 0700);
  54         ksys_chdir("/old");
  55
  56         /* try loading default modules from initrd */
  57         load_default_modules();
  58
  59         /*
  60          * In case that a resume from disk is carried out by linuxrc or one of
  61          * its children, we need to tell the freezer not to wait for us.
  62          */
  63         current->flags |= PF_FREEZER_SKIP;
  64
  65         info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  66                                          GFP_KERNEL, init_linuxrc, NULL, NULL);
  67         if (!info)
  68                 return;
  69         call_usermodehelper_exec(info, UMH_WAIT_PROC);
  70
  71         current->flags &= ~PF_FREEZER_SKIP;
  72
  73         /* move initrd to rootfs' /old */
  74         ksys_mount("..", ".", NULL, MS_MOVE, NULL);
  75         /* switch root and cwd back to / of rootfs */
  76         ksys_chroot("..");
  77
  78         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  79                 ksys_chdir("/old");
  80                 return;
  81         }
  82
  83         ksys_chdir("/");
  84         ROOT_DEV = new_decode_dev(real_root_dev);
  85         mount_root();
  86
  87         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
  88         error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
  89         if (!error)
  90                 printk("okay\n");
  91         else {
  92                 int fd = ksys_open("/dev/root.old", O_RDWR, 0);
  93                 if (error == -ENOENT)
  94                         printk("/initrd does not exist. Ignored.\n");
  95                 else
  96                         printk("failed\n");
  97                 printk(KERN_NOTICE "Unmounting old root\n");
  98                 ksys_umount("/old", MNT_DETACH);
  99                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 100                 if (fd < 0) {
 101                         error = fd;
 102                 } else {
 103                         error = ksys_ioctl(fd, BLKFLSBUF, 0);
 104                         ksys_close(fd);
 105                 }
 106                 printk(!error ? "okay\n" : "failed\n");
 107         }
 108 }
 109
 110 bool __init initrd_load(void)
 111 {
 112         if (mount_initrd) {
 113                 create_dev("/dev/ram", Root_RAM0);
 114                 /*
 115                  * Load the initrd data into /dev/ram0. Execute it as initrd
 116                  * unless /dev/ram0 is supposed to be our actual root device,
 117                  * in that case the ram disk is just set up here, and gets
 118                  * mounted in the normal path.
 119                  */
 120                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 121                         ksys_unlink("/initrd.image");
 122                         handle_initrd();
 123                         return true;
 124                 }
 125         }
 126         ksys_unlink("/initrd.image");
 127         return false;
 128 }