Using this helper allows us to avoid the in-kernel calls to the
sys_chroot() 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_chroot().
In the near future, the fs-external callers of ksys_chroot() should be
converted to use kern_path()/set_fs_root() directly. Then ksys_chroot()
can be moved within sys_chroot() again.
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: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
if (*err)
goto out;
sys_chdir("/.."); /* will traverse into overmounted root */
- sys_chroot(".");
+ ksys_chroot(".");
complete(&setup_done);
while (1) {
spin_lock(&req_lock);
return error;
}
-SYSCALL_DEFINE1(chroot, const char __user *, filename)
+int ksys_chroot(const char __user *filename)
{
struct path path;
int error;
return error;
}
+SYSCALL_DEFINE1(chroot, const char __user *, filename)
+{
+ return ksys_chroot(filename);
+}
+
static int chmod_common(const struct path *path, umode_t mode)
{
struct inode *inode = path->dentry->d_inode;
unsigned long flags, void __user *data);
int ksys_umount(char __user *name, int flags);
int ksys_dup(unsigned int fildes);
+int ksys_chroot(const char __user *filename);
#endif
out:
devtmpfs_mount("dev");
ksys_mount(".", "/", NULL, MS_MOVE, NULL);
- sys_chroot(".");
+ ksys_chroot(".");
}
static bool is_tmpfs;
/* move initrd over / and chdir/chroot in initrd root */
sys_chdir("/root");
ksys_mount(".", "/", NULL, MS_MOVE, NULL);
- sys_chroot(".");
+ ksys_chroot(".");
sys_setsid();
return 0;
}
/* move initrd to rootfs' /old */
ksys_mount("..", ".", NULL, MS_MOVE, NULL);
/* switch root and cwd back to / of rootfs */
- sys_chroot("..");
+ ksys_chroot("..");
if (new_decode_dev(real_root_dev) == Root_RAM0) {
sys_chdir("/old");