init: add an init_chroot helper
Add a simple helper to chroot with a kernel space file name and switch
the early init code over to it. Remove the now unused ksys_chroot.
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/init.c b/fs/init.c
index 64d4e12..2c78f24 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -9,6 +9,7 @@
#include <linux/fs.h>
#include <linux/fs_struct.h>
#include <linux/init_syscalls.h>
+#include <linux/security.h>
#include "internal.h"
int __init init_mount(const char *dev_name, const char *dir_name,
@@ -54,6 +55,29 @@ int __init init_chdir(const char *filename)
return error;
}
+int __init init_chroot(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)
+ goto dput_and_out;
+ error = -EPERM;
+ if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
+ goto dput_and_out;
+ error = security_path_chroot(&path);
+ if (error)
+ goto dput_and_out;
+ set_fs_root(current->fs, &path);
+dput_and_out:
+ path_put(&path);
+ return error;
+}
+
int __init init_unlink(const char *pathname)
{
return do_unlinkat(AT_FDCWD, getname_kernel(pathname));
diff --git a/fs/open.c b/fs/open.c
index 723e0ac..f62f475 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -530,7 +530,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
return error;
}
-int ksys_chroot(const char __user *filename)
+SYSCALL_DEFINE1(chroot, const char __user *, filename)
{
struct path path;
int error;
@@ -563,11 +563,6 @@ int ksys_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;
