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 phys_addr_t phys_initrd_start __initdata;
  20 unsigned long phys_initrd_size __initdata;
  21
  22 static int __init no_initrd(char *str)
  23 {
  24         mount_initrd = 0;
  25         return 1;
  26 }
  27
  28 __setup("noinitrd", no_initrd);
  29
  30 static int __init early_initrd(char *p)
  31 {
  32         phys_addr_t start;
  33         unsigned long size;
  34         char *endp;
  35
  36         start = memparse(p, &endp);
  37         if (*endp == ',') {
  38                 size = memparse(endp + 1, NULL);
  39
  40                 phys_initrd_start = start;
  41                 phys_initrd_size = size;
  42         }
  43         return 0;
  44 }
  45 early_param("initrd", early_initrd);
  46
  47 static int init_linuxrc(struct subprocess_info *info, struct cred *new)
  48 {
  49         ksys_unshare(CLONE_FS | CLONE_FILES);
  50         /* stdin/stdout/stderr for /linuxrc */
  51         ksys_open("/dev/console", O_RDWR, 0);
  52         ksys_dup(0);
  53         ksys_dup(0);
  54         /* move initrd over / and chdir/chroot in initrd root */
  55         ksys_chdir("/root");
  56         ksys_mount(".", "/", NULL, MS_MOVE, NULL);
  57         ksys_chroot(".");
  58         ksys_setsid();
  59         return 0;
  60 }
  61
  62 static void __init handle_initrd(void)
  63 {
  64         struct subprocess_info *info;
  65         static char *argv[] = { "linuxrc", NULL, };
  66         extern char *envp_init[];
  67         int error;
  68
  69         real_root_dev = new_encode_dev(ROOT_DEV);
  70         create_dev("/dev/root.old", Root_RAM0);
  71         /* mount initrd on rootfs' /root */
  72         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  73         ksys_mkdir("/old", 0700);
  74         ksys_chdir("/old");
  75
  76         /*
  77          * In case that a resume from disk is carried out by linuxrc or one of
  78          * its children, we need to tell the freezer not to wait for us.
  79          */
  80         current->flags |= PF_FREEZER_SKIP;
  81
  82         info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  83                                          GFP_KERNEL, init_linuxrc, NULL, NULL);
  84         if (!info)
  85                 return;
  86         call_usermodehelper_exec(info, UMH_WAIT_PROC);
  87
  88         current->flags &= ~PF_FREEZER_SKIP;
  89
  90         /* move initrd to rootfs' /old */
  91         ksys_mount("..", ".", NULL, MS_MOVE, NULL);
  92         /* switch root and cwd back to / of rootfs */
  93         ksys_chroot("..");
  94
  95         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  96                 ksys_chdir("/old");
  97                 return;
  98         }
  99
 100         ksys_chdir("/");
 101         ROOT_DEV = new_decode_dev(real_root_dev);
 102         mount_root();
 103
 104         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
 105         error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
 106         if (!error)
 107                 printk("okay\n");
 108         else {
 109                 int fd = ksys_open("/dev/root.old", O_RDWR, 0);
 110                 if (error == -ENOENT)
 111                         printk("/initrd does not exist. Ignored.\n");
 112                 else
 113                         printk("failed\n");
 114                 printk(KERN_NOTICE "Unmounting old root\n");
 115                 ksys_umount("/old", MNT_DETACH);
 116                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 117                 if (fd < 0) {
 118                         error = fd;
 119                 } else {
 120                         error = ksys_ioctl(fd, BLKFLSBUF, 0);
 121                         ksys_close(fd);
 122                 }
 123                 printk(!error ? "okay\n" : "failed\n");
 124         }
 125 }
 126
 127 bool __init initrd_load(void)
 128 {
 129         if (mount_initrd) {
 130                 create_dev("/dev/ram", Root_RAM0);
 131                 /*
 132                  * Load the initrd data into /dev/ram0. Execute it as initrd
 133                  * unless /dev/ram0 is supposed to be our actual root device,
 134                  * in that case the ram disk is just set up here, and gets
 135                  * mounted in the normal path.
 136                  */
 137                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 138                         ksys_unlink("/initrd.image");
 139                         handle_initrd();
 140                         return true;
 141                 }
 142         }
 143         ksys_unlink("/initrd.image");
 144         return false;
 145 }