LXR linux/init/do_mounts

   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
  24unsigned long initrd_start, initrd_end;
  25int initrd_below_start_ok;
  26unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  27static int __initdata mount_initrd = 1;
  28
  29static int __init no_initrd(char *str)
  30{
  31        mount_initrd = 0;
  32        return 1;
  33}
  34
  35__setup("noinitrd", no_initrd);
  36
  37static 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
  52static 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
 120bool __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}
 139