init: add an init_chdir helper

Add a simple helper to chdir with a kernel space file name and switch
the early init code over to it.  Remove the now unused ksys_chdir.

Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Christoph Hellwig 2020-07-22 11:25:21 +02:00
parent 20cce026c3
commit db63f1e315
7 changed files with 24 additions and 13 deletions

View File

@ -412,7 +412,7 @@ static int __init devtmpfs_setup(void *p)
err = init_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
if (err)
goto out;
ksys_chdir("/.."); /* will traverse into overmounted root */
init_chdir("/.."); /* will traverse into overmounted root */
ksys_chroot(".");
out:
*(int *)p = err;

View File

@ -7,6 +7,7 @@
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/fs.h>
#include <linux/fs_struct.h>
#include <linux/init_syscalls.h>
#include "internal.h"
@ -38,6 +39,21 @@ int __init init_umount(const char *name, int flags)
return path_umount(&path, flags);
}
int __init init_chdir(const char *filename)
{
struct path path;
int error;
error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
if (error)
return error;
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
if (!error)
set_fs_pwd(current->fs, &path);
path_put(&path);
return error;
}
int __init init_unlink(const char *pathname)
{
return do_unlinkat(AT_FDCWD, getname_kernel(pathname));

View File

@ -482,7 +482,7 @@ SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
return do_faccessat(AT_FDCWD, filename, mode, 0);
}
int ksys_chdir(const char __user *filename)
SYSCALL_DEFINE1(chdir, const char __user *, filename)
{
struct path path;
int error;
@ -508,11 +508,6 @@ out:
return error;
}
SYSCALL_DEFINE1(chdir, const char __user *, filename)
{
return ksys_chdir(filename);
}
SYSCALL_DEFINE1(fchdir, unsigned int, fd)
{
struct fd f = fdget_raw(fd);

View File

@ -3,5 +3,6 @@
int __init init_mount(const char *dev_name, const char *dir_name,
const char *type_page, unsigned long flags, void *data_page);
int __init init_umount(const char *name, int flags);
int __init init_chdir(const char *filename);
int __init init_unlink(const char *pathname);
int __init init_rmdir(const char *pathname);

View File

@ -1238,7 +1238,6 @@ asmlinkage long sys_ni_syscall(void);
int ksys_chroot(const char __user *filename);
ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count);
int ksys_chdir(const char __user *filename);
int ksys_fchown(unsigned int fd, uid_t user, gid_t group);
ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count);
void ksys_sync(void);

View File

@ -408,7 +408,7 @@ static int __init do_mount_root(const char *name, const char *fs,
if (ret)
goto out;
ksys_chdir("/root");
init_chdir("/root");
s = current->fs->pwd.dentry->d_sb;
ROOT_DEV = s->s_dev;
printk(KERN_INFO

View File

@ -61,7 +61,7 @@ static int __init init_linuxrc(struct subprocess_info *info, struct cred *new)
ksys_unshare(CLONE_FS | CLONE_FILES);
console_on_rootfs();
/* move initrd over / and chdir/chroot in initrd root */
ksys_chdir("/root");
init_chdir("/root");
init_mount(".", "/", NULL, MS_MOVE, NULL);
ksys_chroot(".");
ksys_setsid();
@ -82,7 +82,7 @@ static void __init handle_initrd(void)
/* mount initrd on rootfs' /root */
mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
ksys_mkdir("/old", 0700);
ksys_chdir("/old");
init_chdir("/old");
/*
* In case that a resume from disk is carried out by linuxrc or one of
@ -104,11 +104,11 @@ static void __init handle_initrd(void)
ksys_chroot("..");
if (new_decode_dev(real_root_dev) == Root_RAM0) {
ksys_chdir("/old");
init_chdir("/old");
return;
}
ksys_chdir("/");
init_chdir("/");
ROOT_DEV = new_decode_dev(real_root_dev);
mount_root();