fs: add ksys_chroot() helper; remove-in kernel calls to sys_chroot()
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>
diff --git a/fs/open.c b/fs/open.c
index 7ea1184..7a475e8 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -479,7 +479,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
return error;
}
-SYSCALL_DEFINE1(chroot, const char __user *, filename)
+int ksys_chroot(const char __user *filename)
{
struct path path;
int error;
@@ -512,6 +512,11 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
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;