init/do_mounts_initrd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Many of the syscalls used in this file expect some of the arguments
   4  * to be __user pointers not __kernel pointers.  To limit the sparse
   5  * noise, turn off sparse checking for this file.
   6  */
   7 #ifdef __CHECKER__
   8 #undef __CHECKER__
   9 #warning "Sparse checking disabled for this file"
  10 #endif
  11
  12 #include <linux/unistd.h>
  13 #include <linux/kernel.h>
  14 #include <linux/fs.h>
  15 #include <linux/minix_fs.h>
  16 #include <linux/romfs_fs.h>
  17 #include <linux/initrd.h>
  18 #include <linux/sched.h>
  19 #include <linux/freezer.h>
  20 #include <linux/kmod.h>
  21
  22 #include "do_mounts.h"
  23
  24 unsigned long initrd_start, initrd_end;
  25 int initrd_below_start_ok;
  26 unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  27 static int __initdata mount_initrd = 1;
  28
  29 static int __init no_initrd(char *str)
  30 {
  31         mount_initrd = 0;
  32         return 1;
  33 }
  34
  35 __setup("noinitrd", no_initrd);
  36
  37 static int init_linuxrc(struct subprocess_info *info, struct cred *new)
  38 {
  39         ksys_unshare(CLONE_FS | CLONE_FILES);
  40         /* stdin/stdout/stderr for /linuxrc */
  41         ksys_open("/dev/console", O_RDWR, 0);
  42         ksys_dup(0);
  43         ksys_dup(0);
  44         /* move initrd over / and chdir/chroot in initrd root */
  45         ksys_chdir("/root");
  46         ksys_mount(".", "/", NULL, MS_MOVE, NULL);
  47         ksys_chroot(".");
  48         ksys_setsid();
  49         return 0;
  50 }
  51
  52 static void __init handle_initrd(void)
  53 {
  54         struct subprocess_info *info;
  55         static char *argv[] = { "linuxrc", NULL, };
  56         extern char *envp_init[];
  57         int error;
  58
  59         real_root_dev = new_encode_dev(ROOT_DEV);
  60         create_dev("/dev/root.old", Root_RAM0);
  61         /* mount initrd on rootfs' /root */
  62         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  63         ksys_mkdir("/old", 0700);
  64         ksys_chdir("/old");
  65
  66         /* try loading default modules from initrd */
  67         load_default_modules();
  68
  69         /*
  70          * In case that a resume from disk is carried out by linuxrc or one of
  71          * its children, we need to tell the freezer not to wait for us.
  72          */
  73         current->flags |= PF_FREEZER_SKIP;
  74
  75         info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  76                                          GFP_KERNEL, init_linuxrc, NULL, NULL);
  77         if (!info)
  78                 return;
  79         call_usermodehelper_exec(info, UMH_WAIT_PROC);
  80
  81         current->flags &= ~PF_FREEZER_SKIP;
  82
  83         /* move initrd to rootfs' /old */
  84         ksys_mount("..", ".", NULL, MS_MOVE, NULL);
  85         /* switch root and cwd back to / of rootfs */
  86         ksys_chroot("..");
  87
  88         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  89                 ksys_chdir("/old");
  90                 return;
  91         }
  92
  93         ksys_chdir("/");
  94         ROOT_DEV = new_decode_dev(real_root_dev);
  95         mount_root();
  96
  97         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
  98         error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
  99         if (!error)
 100                 printk("okay\n");
 101         else {
 102                 int fd = ksys_open("/dev/root.old", O_RDWR, 0);
 103                 if (error == -ENOENT)
 104                         printk("/initrd does not exist. Ignored.\n");
 105                 else
 106                         printk("failed\n");
 107                 printk(KERN_NOTICE "Unmounting old root\n");
 108                 ksys_umount("/old", MNT_DETACH);
 109                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 110                 if (fd < 0) {
 111                         error = fd;
 112                 } else {
 113                         error = ksys_ioctl(fd, BLKFLSBUF, 0);
 114                         ksys_close(fd);
 115                 }
 116                 printk(!error ? "okay\n" : "failed\n");
 117         }
 118 }
 119
 120 bool __init initrd_load(void)
 121 {
 122         if (mount_initrd) {
 123                 create_dev("/dev/ram", Root_RAM0);
 124                 /*
 125                  * Load the initrd data into /dev/ram0. Execute it as initrd
 126                  * unless /dev/ram0 is supposed to be our actual root device,
 127                  * in that case the ram disk is just set up here, and gets
 128                  * mounted in the normal path.
 129                  */
 130                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 131                         ksys_unlink("/initrd.image");
 132                         handle_initrd();
 133                         return true;
 134                 }
 135         }
 136         ksys_unlink("/initrd.image");
 137         return false;
 138 }