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         /* stdin/stdout/stderr for /linuxrc */
  52         ksys_open("/dev/console", O_RDWR, 0);
  53         ksys_dup(0);
  54         ksys_dup(0);
  55         /* move initrd over / and chdir/chroot in initrd root */
  56         ksys_chdir("/root");
  57         ksys_mount(".", "/", NULL, MS_MOVE, NULL);
  58         ksys_chroot(".");
  59         ksys_setsid();
  60         return 0;
  61 }
  62
  63 static void __init handle_initrd(void)
  64 {
  65         struct subprocess_info *info;
  66         static char *argv[] = { "linuxrc", NULL, };
  67         extern char *envp_init[];
  68         int error;
  69
  70         real_root_dev = new_encode_dev(ROOT_DEV);
  71         create_dev("/dev/root.old", Root_RAM0);
  72         /* mount initrd on rootfs' /root */
  73         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  74         ksys_mkdir("/old", 0700);
  75         ksys_chdir("/old");
  76
  77         /*
  78          * In case that a resume from disk is carried out by linuxrc or one of
  79          * its children, we need to tell the freezer not to wait for us.
  80          */
  81         current->flags |= PF_FREEZER_SKIP;
  82
  83         info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  84                                          GFP_KERNEL, init_linuxrc, NULL, NULL);
  85         if (!info)
  86                 return;
  87         call_usermodehelper_exec(info, UMH_WAIT_PROC);
  88
  89         current->flags &= ~PF_FREEZER_SKIP;
  90
  91         /* move initrd to rootfs' /old */
  92         ksys_mount("..", ".", NULL, MS_MOVE, NULL);
  93         /* switch root and cwd back to / of rootfs */
  94         ksys_chroot("..");
  95
  96         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  97                 ksys_chdir("/old");
  98                 return;
  99         }
 100
 101         ksys_chdir("/");
 102         ROOT_DEV = new_decode_dev(real_root_dev);
 103         mount_root();
 104
 105         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
 106         error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
 107         if (!error)
 108                 printk("okay\n");
 109         else {
 110                 int fd = ksys_open("/dev/root.old", O_RDWR, 0);
 111                 if (error == -ENOENT)
 112                         printk("/initrd does not exist. Ignored.\n");
 113                 else
 114                         printk("failed\n");
 115                 printk(KERN_NOTICE "Unmounting old root\n");
 116                 ksys_umount("/old", MNT_DETACH);
 117                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 118                 if (fd < 0) {
 119                         error = fd;
 120                 } else {
 121                         error = ksys_ioctl(fd, BLKFLSBUF, 0);
 122                         ksys_close(fd);
 123                 }
 124                 printk(!error ? "okay\n" : "failed\n");
 125         }
 126 }
 127
 128 bool __init initrd_load(void)
 129 {
 130         if (mount_initrd) {
 131                 create_dev("/dev/ram", Root_RAM0);
 132                 /*
 133                  * Load the initrd data into /dev/ram0. Execute it as initrd
 134                  * unless /dev/ram0 is supposed to be our actual root device,
 135                  * in that case the ram disk is just set up here, and gets
 136                  * mounted in the normal path.
 137                  */
 138                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 139                         ksys_unlink("/initrd.image");
 140                         handle_initrd();
 141                         return true;
 142                 }
 143         }
 144         ksys_unlink("/initrd.image");
 145         return false;
 146 }