mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-22 20:23:57 +08:00
e2aaa9f423
Using this helper allows us to avoid the in-kernel call to the sys_setsid() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_setsid(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
139 lines
3.5 KiB
C
139 lines
3.5 KiB
C
// 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)
|
|
{
|
|
ksys_unshare(CLONE_FS | CLONE_FILES);
|
|
/* stdin/stdout/stderr for /linuxrc */
|
|
ksys_open("/dev/console", O_RDWR, 0);
|
|
ksys_dup(0);
|
|
ksys_dup(0);
|
|
/* move initrd over / and chdir/chroot in initrd root */
|
|
ksys_chdir("/root");
|
|
ksys_mount(".", "/", NULL, MS_MOVE, NULL);
|
|
ksys_chroot(".");
|
|
ksys_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);
|
|
ksys_mkdir("/old", 0700);
|
|
ksys_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 */
|
|
ksys_mount("..", ".", NULL, MS_MOVE, NULL);
|
|
/* switch root and cwd back to / of rootfs */
|
|
ksys_chroot("..");
|
|
|
|
if (new_decode_dev(real_root_dev) == Root_RAM0) {
|
|
ksys_chdir("/old");
|
|
return;
|
|
}
|
|
|
|
ksys_chdir("/");
|
|
ROOT_DEV = new_decode_dev(real_root_dev);
|
|
mount_root();
|
|
|
|
printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
|
|
error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
|
|
if (!error)
|
|
printk("okay\n");
|
|
else {
|
|
int fd = ksys_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");
|
|
ksys_umount("/old", MNT_DETACH);
|
|
printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
|
|
if (fd < 0) {
|
|
error = fd;
|
|
} else {
|
|
error = ksys_ioctl(fd, BLKFLSBUF, 0);
|
|
ksys_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) {
|
|
ksys_unlink("/initrd.image");
|
|
handle_initrd();
|
|
return true;
|
|
}
|
|
}
|
|
ksys_unlink("/initrd.image");
|
|
return false;
|
|
}
|