4.14-stable patches

[thirdparty/kernel/stable-queue.git] / releases / 2.6.32.3 / generic_permission-may_open-is-not-write-access.patch

From 7ea6600148c265b1fd53e521022b1d7aec81d974 Mon Sep 17 00:00:00 2001
From: Serge E. Hallyn <serue@us.ibm.com>
Date: Tue, 29 Dec 2009 14:50:19 -0600
Subject: generic_permission: MAY_OPEN is not write access

From: Serge E. Hallyn <serue@us.ibm.com>

commit 7ea6600148c265b1fd53e521022b1d7aec81d974 upstream.

generic_permission was refusing CAP_DAC_READ_SEARCH-enabled
processes from opening DAC-protected files read-only, because
do_filp_open adds MAY_OPEN to the open mask.

Ignore MAY_OPEN.  After this patch, CAP_DAC_READ_SEARCH is
again sufficient to open(fname, O_RDONLY) on a file to which
DAC otherwise refuses us read permission.

Reported-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 fs/namei.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -234,6 +234,7 @@ int generic_permission(struct inode *ino
 	/*
 	 * Searching includes executable on directories, else just read.
 	 */
+	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 	if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
 		if (capable(CAP_DAC_READ_SEARCH))
 			return 0;