selinux: convert the policy type_attr_map to flex_array

Current selinux policy can have over 3000 types.  The type_attr_map in
policy is an array sized by the number of types times sizeof(struct ebitmap)
(12 on x86_64).  Basic math tells us the array is going to be of length
3000 x 12 = 36,000 bytes.  The largest 'safe' allocation on a long running
system is 16k.  Most of the time a 32k allocation will work.  But on long
running systems a 64k allocation (what we need) can fail quite regularly.
In order to deal with this I am converting the type_attr_map to use
flex_arrays.  Let the library code deal with breaking this into PAGE_SIZE
pieces.

-v2
rework some of the if(!obj) BUG() to be BUG_ON(!obj)
drop flex_array_put() calls and just use a _get() object directly

-v3
make apply to James' tree (drop the policydb_write changes)

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by:  Stephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 1de60ce90d9a..9ea2feca3cd4 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -50,6 +50,7 @@
 #include <linux/audit.h>
 #include <linux/mutex.h>
 #include <linux/selinux.h>
+#include <linux/flex_array.h>
 #include <net/netlabel.h>
 
 #include "flask.h"
@@ -626,8 +627,10 @@ static void context_struct_compute_av(struct context *scontext,
 	 */
 	avkey.target_class = tclass;
 	avkey.specified = AVTAB_AV;
-	sattr = &policydb.type_attr_map[scontext->type - 1];
-	tattr = &policydb.type_attr_map[tcontext->type - 1];
+	sattr = flex_array_get(policydb.type_attr_map_array, scontext->type - 1);
+	BUG_ON(!sattr);
+	tattr = flex_array_get(policydb.type_attr_map_array, tcontext->type - 1);
+	BUG_ON(!tattr);
 	ebitmap_for_each_positive_bit(sattr, snode, i) {
 		ebitmap_for_each_positive_bit(tattr, tnode, j) {
 			avkey.source_type = i + 1;