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 #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 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 static int __init no_initrd(char *str)
  24 {
  25         mount_initrd = 0;
  26         return 1;
  27 }
  28
  29 __setup("noinitrd", no_initrd);
  30
  31 static int __init early_initrd(char *p)
  32 {
  33         phys_addr_t start;
  34         unsigned long size;
  35         char *endp;
  36
  37         start = memparse(p, &endp);
  38         if (*endp == ',') {
  39                 size = memparse(endp + 1, NULL);
  40
  41                 phys_initrd_start = start;
  42                 phys_initrd_size = size;
  43         }
  44         return 0;
  45 }
  46 early_param("initrd", early_initrd);
  47
  48 static int init_linuxrc(struct subprocess_info *info, struct cred *new)
  49 {
  50         ksys_unshare(CLONE_FS | CLONE_FILES);
  51         console_on_rootfs();
  52         /* move initrd over / and chdir/chroot in initrd root */
  53         ksys_chdir("/root");
  54         do_mount(".", "/", NULL, MS_MOVE, NULL);
  55         ksys_chroot(".");
  56         ksys_setsid();
  57         return 0;
  58 }
  59
  60 static void __init handle_initrd(void)
  61 {
  62         struct subprocess_info *info;
  63         static char *argv[] = { "linuxrc", NULL, };
  64         extern char *envp_init[];
  65         int error;
  66
  67         real_root_dev = new_encode_dev(ROOT_DEV);
  68         create_dev("/dev/root.old", Root_RAM0);
  69         /* mount initrd on rootfs' /root */
  70         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  71         ksys_mkdir("/old", 0700);
  72         ksys_chdir("/old");
  73
  74         /*
  75          * In case that a resume from disk is carried out by linuxrc or one of
  76          * its children, we need to tell the freezer not to wait for us.
  77          */
  78         current->flags |= PF_FREEZER_SKIP;
  79
  80         info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  81                                          GFP_KERNEL, init_linuxrc, NULL, NULL);
  82         if (!info)
  83                 return;
  84         call_usermodehelper_exec(info, UMH_WAIT_PROC);
  85
  86         current->flags &= ~PF_FREEZER_SKIP;
  87
  88         /* move initrd to rootfs' /old */
  89         do_mount("..", ".", NULL, MS_MOVE, NULL);
  90         /* switch root and cwd back to / of rootfs */
  91         ksys_chroot("..");
  92
  93         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  94                 ksys_chdir("/old");
  95                 return;
  96         }
  97
  98         ksys_chdir("/");
  99         ROOT_DEV = new_decode_dev(real_root_dev);
 100         mount_root();
 101
 102         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
 103         error = do_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
 104         if (!error)
 105                 printk("okay\n");
 106         else {
 107                 int fd = ksys_open("/dev/root.old", O_RDWR, 0);
 108                 if (error == -ENOENT)
 109                         printk("/initrd does not exist. Ignored.\n");
 110                 else
 111                         printk("failed\n");
 112                 printk(KERN_NOTICE "Unmounting old root\n");
 113                 ksys_umount("/old", MNT_DETACH);
 114                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 115                 if (fd < 0) {
 116                         error = fd;
 117                 } else {
 118                         error = ksys_ioctl(fd, BLKFLSBUF, 0);
 119                         ksys_close(fd);
 120                 }
 121                 printk(!error ? "okay\n" : "failed\n");
 122         }
 123 }
 124
 125 bool __init initrd_load(void)
 126 {
 127         if (mount_initrd) {
 128                 create_dev("/dev/ram", Root_RAM0);
 129                 /*
 130                  * Load the initrd data into /dev/ram0. Execute it as initrd
 131                  * unless /dev/ram0 is supposed to be our actual root device,
 132                  * in that case the ram disk is just set up here, and gets
 133                  * mounted in the normal path.
 134                  */
 135                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 136                         ksys_unlink("/initrd.image");
 137                         handle_initrd();
 138                         return true;
 139                 }
 140         }
 141         ksys_unlink("/initrd.image");
 142         return false;
 143 }