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Copy pathdo_mounts_initrd.c
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138 lines (121 loc) · 3.47 KB
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// SPDX-License-Identifier: GPL-2.0
/*
* Many of the syscalls used in this file expect some of the arguments
* to be __user pointers not __kernel pointers. To limit the sparse
* noise, turn off sparse checking for this file.
*/
#ifdef __CHECKER__
#undef __CHECKER__
#warning "Sparse checking disabled for this file"
#endif
#include <linux/unistd.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/minix_fs.h>
#include <linux/romfs_fs.h>
#include <linux/initrd.h>
#include <linux/sched.h>
#include <linux/freezer.h>
#include <linux/kmod.h>
#include "do_mounts.h"
unsigned long initrd_start, initrd_end;
int initrd_below_start_ok;
unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
static int __initdata mount_initrd = 1;
static int __init no_initrd(char *str)
{
mount_initrd = 0;
return 1;
}
__setup("noinitrd", no_initrd);
static int init_linuxrc(struct subprocess_info *info, struct cred *new)
{
sys_unshare(CLONE_FS | CLONE_FILES);
/* stdin/stdout/stderr for /linuxrc */
sys_open("/dev/console", O_RDWR, 0);
sys_dup(0);
sys_dup(0);
/* move initrd over / and chdir/chroot in initrd root */
sys_chdir("/root");
sys_mount(".", "/", NULL, MS_MOVE, NULL);
sys_chroot(".");
sys_setsid();
return 0;
}
static void __init handle_initrd(void)
{
struct subprocess_info *info;
static char *argv[] = { "linuxrc", NULL, };
extern char *envp_init[];
int error;
real_root_dev = new_encode_dev(ROOT_DEV);
create_dev("/dev/root.old", Root_RAM0);
/* mount initrd on rootfs' /root */
mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
sys_mkdir("/old", 0700);
sys_chdir("/old");
/* try loading default modules from initrd */
load_default_modules();
/*
* In case that a resume from disk is carried out by linuxrc or one of
* its children, we need to tell the freezer not to wait for us.
*/
current->flags |= PF_FREEZER_SKIP;
info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
GFP_KERNEL, init_linuxrc, NULL, NULL);
if (!info)
return;
call_usermodehelper_exec(info, UMH_WAIT_PROC);
current->flags &= ~PF_FREEZER_SKIP;
/* move initrd to rootfs' /old */
sys_mount("..", ".", NULL, MS_MOVE, NULL);
/* switch root and cwd back to / of rootfs */
sys_chroot("..");
if (new_decode_dev(real_root_dev) == Root_RAM0) {
sys_chdir("/old");
return;
}
sys_chdir("/");
ROOT_DEV = new_decode_dev(real_root_dev);
mount_root();
printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
if (!error)
printk("okay\n");
else {
int fd = sys_open("/dev/root.old", O_RDWR, 0);
if (error == -ENOENT)
printk("/initrd does not exist. Ignored.\n");
else
printk("failed\n");
printk(KERN_NOTICE "Unmounting old root\n");
sys_umount("/old", MNT_DETACH);
printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
if (fd < 0) {
error = fd;
} else {
error = sys_ioctl(fd, BLKFLSBUF, 0);
sys_close(fd);
}
printk(!error ? "okay\n" : "failed\n");
}
}
bool __init initrd_load(void)
{
if (mount_initrd) {
create_dev("/dev/ram", Root_RAM0);
/*
* Load the initrd data into /dev/ram0. Execute it as initrd
* unless /dev/ram0 is supposed to be our actual root device,
* in that case the ram disk is just set up here, and gets
* mounted in the normal path.
*/
if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
sys_unlink("/initrd.image");
handle_initrd();
return true;
}
}
sys_unlink("/initrd.image");
return false;
}