LXR linux/init/do_mounts

   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
  15unsigned long initrd_start, initrd_end;
  16int initrd_below_start_ok;
  17unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  18static int __initdata mount_initrd = 1;
  19
  20phys_addr_t phys_initrd_start __initdata;
  21unsigned long phys_initrd_size __initdata;
  22
  23static int __init no_initrd(char *str)
  24{
  25        mount_initrd = 0;
  26        return 1;
  27}
  28
  29__setup("noinitrd", no_initrd);
  30
  31static 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}
  46early_param("initrd", early_initrd);
  47
  48static 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
  63static 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
 128bool __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}
 147