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_initrdmem(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("initrdmem", early_initrdmem);
  47
  48 /*
  49  * This is here as the initrd keyword has been in use since 11/2018
  50  * on ARM, PowerPC, and MIPS.
  51  * It should not be; it is reserved for bootloaders.
  52  */
  53 static int __init early_initrd(char *p)
  54 {
  55         return early_initrdmem(p);
  56 }
  57 early_param("initrd", early_initrd);
  58
  59 static int init_linuxrc(struct subprocess_info *info, struct cred *new)
  60 {
  61         ksys_unshare(CLONE_FS | CLONE_FILES);
  62         console_on_rootfs();
  63         /* move initrd over / and chdir/chroot in initrd root */
  64         ksys_chdir("/root");
  65         do_mount(".", "/", NULL, MS_MOVE, NULL);
  66         ksys_chroot(".");
  67         ksys_setsid();
  68         return 0;
  69 }
  70
  71 static void __init handle_initrd(void)
  72 {
  73         struct subprocess_info *info;
  74         static char *argv[] = { "linuxrc", NULL, };
  75         extern char *envp_init[];
  76         int error;
  77
  78         real_root_dev = new_encode_dev(ROOT_DEV);
  79         create_dev("/dev/root.old", Root_RAM0);
  80         /* mount initrd on rootfs' /root */
  81         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  82         ksys_mkdir("/old", 0700);
  83         ksys_chdir("/old");
  84
  85         /*
  86          * In case that a resume from disk is carried out by linuxrc or one of
  87          * its children, we need to tell the freezer not to wait for us.
  88          */
  89         current->flags |= PF_FREEZER_SKIP;
  90
  91         info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  92                                          GFP_KERNEL, init_linuxrc, NULL, NULL);
  93         if (!info)
  94                 return;
  95         call_usermodehelper_exec(info, UMH_WAIT_PROC);
  96
  97         current->flags &= ~PF_FREEZER_SKIP;
  98
  99         /* move initrd to rootfs' /old */
 100         do_mount("..", ".", NULL, MS_MOVE, NULL);
 101         /* switch root and cwd back to / of rootfs */
 102         ksys_chroot("..");
 103
 104         if (new_decode_dev(real_root_dev) == Root_RAM0) {
 105                 ksys_chdir("/old");
 106                 return;
 107         }
 108
 109         ksys_chdir("/");
 110         ROOT_DEV = new_decode_dev(real_root_dev);
 111         mount_root();
 112
 113         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
 114         error = do_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
 115         if (!error)
 116                 printk("okay\n");
 117         else {
 118                 int fd = ksys_open("/dev/root.old", O_RDWR, 0);
 119                 if (error == -ENOENT)
 120                         printk("/initrd does not exist. Ignored.\n");
 121                 else
 122                         printk("failed\n");
 123                 printk(KERN_NOTICE "Unmounting old root\n");
 124                 ksys_umount("/old", MNT_DETACH);
 125                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 126                 if (fd < 0) {
 127                         error = fd;
 128                 } else {
 129                         error = ksys_ioctl(fd, BLKFLSBUF, 0);
 130                         ksys_close(fd);
 131                 }
 132                 printk(!error ? "okay\n" : "failed\n");
 133         }
 134 }
 135
 136 bool __init initrd_load(void)
 137 {
 138         if (mount_initrd) {
 139                 create_dev("/dev/ram", Root_RAM0);
 140                 /*
 141                  * Load the initrd data into /dev/ram0. Execute it as initrd
 142                  * unless /dev/ram0 is supposed to be our actual root device,
 143                  * in that case the ram disk is just set up here, and gets
 144                  * mounted in the normal path.
 145                  */
 146                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 147                         ksys_unlink("/initrd.image");
 148                         handle_initrd();
 149                         return true;
 150                 }
 151         }
 152         ksys_unlink("/initrd.image");
 153         return false;
 154 }