From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 7 Jul 2012 17:17:00 +0000 (-0700)
Subject: vfs: make O_PATH file descriptors usable for 'fchdir()'
X-Git-Tag: v3.2.23~1
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f6d2d473ca73cb30cf25a6940b1dff3cc78b513f;p=karo-tx-linux.git

vfs: make O_PATH file descriptors usable for 'fchdir()'

commit 332a2e1244bd08b9e3ecd378028513396a004a24 upstream.

We already use them for openat() and friends, but fchdir() also wants to
be able to use O_PATH file descriptors.  This should make it comparable
to the O_SEARCH of Solaris.  In particular, O_PATH allows you to access
(not-quite-open) a directory you don't have read persmission to, only
execute permission.

Noticed during development of multithread support for ksh93.

Reported-by: ольга крыжановская <olga.kryzhanovska@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/fs/open.c b/fs/open.c
index 22c41b543f2d..e2b5d515bfc9 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -396,10 +396,10 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 {
 	struct file *file;
 	struct inode *inode;
-	int error;
+	int error, fput_needed;
 
 	error = -EBADF;
-	file = fget(fd);
+	file = fget_raw_light(fd, &fput_needed);
 	if (!file)
 		goto out;
 
@@ -413,7 +413,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 	if (!error)
 		set_fs_pwd(current->fs, &file->f_path);
 out_putf:
-	fput(file);
+	fput_light(file, fput_needed);
 out:
 	return error;
 }