[3.19.y-ckt stable] Patch "selinux: don't waste ebitmap space when importing NetLabel categories" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    selinux: don't waste ebitmap space when importing NetLabel categories

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 277fc71758f67e79fad5f0a4640ec3aa140f0d50 Mon Sep 17 00:00:00 2001
From: Paul Moore <pmoore at redhat.com>
Date: Thu, 9 Jul 2015 14:20:36 -0400
Subject: selinux: don't waste ebitmap space when importing NetLabel categories

commit 3324603524925c7727207027d1c15e597412d15e upstream.

At present we don't create efficient ebitmaps when importing NetLabel
category bitmaps.  This can present a problem when comparing ebitmaps
since ebitmap_cmp() is very strict about these things and considers
these wasteful ebitmaps not equal when compared to their more
efficient counterparts, even if their values are the same.  This isn't
likely to cause problems on 64-bit systems due to a bit of luck on
how NetLabel/CIPSO works and the default ebitmap size, but it can be
a problem on 32-bit systems.

This patch fixes this problem by being a bit more intelligent when
importing NetLabel category bitmaps by skipping over empty sections
which should result in a nice, efficient ebitmap.

Signed-off-by: Paul Moore <pmoore at redhat.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 security/selinux/ss/ebitmap.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index afe6a26..57644b1 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -153,6 +153,12 @@ int ebitmap_netlbl_import(struct ebitmap *ebmap,
 		if (offset == (u32)-1)
 			return 0;

+		/* don't waste ebitmap space if the netlabel bitmap is empty */
+		if (bitmap == 0) {
+			offset += EBITMAP_UNIT_SIZE;
+			continue;
+		}
+
 		if (e_iter == NULL ||
 		    offset >= e_iter->startbit + EBITMAP_SIZE) {
 			e_prev = e_iter;
--
1.9.1