Commit 3f9f0aa6 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

VFS: clean up and simplify getname_flags() 

This removes a number of silly games around strncpy_from_user() in
do_getname(), and removes that helper function entirely.  We instead
make getname_flags() just use strncpy_from_user() properly directly.

Removing the wrapper function simplifies things noticeably, mostly
because we no longer play the unnecessary games with segments (x86
strncpy_from_user() no longer needs the hack), but also because the
empty path handling is just much more obvious.  The return value of
"strncpy_to_user()" is much more obvious than checking an odd error
return case from do_getname().

[ non-x86 architectures were notified of this change several weeks ago,
  since it is possible that they have copied the old broken x86
  strncpy_from_user. But nobody reacted, so .. See

    http://www.spinics.net/lists/linux-arch/msg17313.html



  for details ]

Cc: linux-arch@vger.kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 07497083

fs/namei.c

+24 −34
Original line number Diff line number Diff line
@@ -116,49 +116,39 @@ 
 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).

 * PATH_MAX includes the nul terminator --RR.

 */

static int do_getname(const char __user *filename, char *page)

{

	int retval;

	unsigned long len = PATH_MAX;



	if (!segment_eq(get_fs(), KERNEL_DS)) {

		if ((unsigned long) filename >= TASK_SIZE)

			return -EFAULT;

		if (TASK_SIZE - (unsigned long) filename < PATH_MAX)

			len = TASK_SIZE - (unsigned long) filename;

	}



	retval = strncpy_from_user(page, filename, len);

	if (retval > 0) {

		if (retval < len)

			return 0;

		return -ENAMETOOLONG;

	} else if (!retval)

		retval = -ENOENT;

	return retval;

}



static char *getname_flags(const char __user *filename, int flags, int *empty)

{

	char *result = __getname();

	int retval;

	char *result = __getname(), *err;

	int len;



	if (!result)

	if (unlikely(!result))

		return ERR_PTR(-ENOMEM);



	retval = do_getname(filename, result);

	if (retval < 0) {

		if (retval == -ENOENT && empty)

	len = strncpy_from_user(result, filename, PATH_MAX);

	err = ERR_PTR(len);

	if (unlikely(len < 0))

		goto error;



	/* The empty path is special. */

	if (unlikely(!len)) {

		if (empty)

			*empty = 1;

		if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {

			__putname(result);

			return ERR_PTR(retval);

		}

		err = ERR_PTR(-ENOENT);

		if (!(flags & LOOKUP_EMPTY))

			goto error;

	}



	err = ERR_PTR(-ENAMETOOLONG);

	if (likely(len < PATH_MAX)) {

		audit_getname(result);

		return result;

	}



error:

	__putname(result);

	return err;

}



char *getname(const char __user * filename)

{

	return getname_flags(filename, 0, NULL);

CRA Git | Maintained and supported by SUSTech CRA and CCSE