Commit 6371dcd3 authored by Eric Paris's avatar Eric Paris Committed by James Morris
Browse files

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: default avatarEric Paris <eparis@redhat.com>
Acked-by: default avatarStephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent 016d825f

security/selinux/ss/policydb.c

+31 −10
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/string.h>

#include <linux/errno.h>

#include <linux/audit.h>

#include <linux/flex_array.h>

#include "security.h"



#include "policydb.h"
@@ -739,11 +740,17 @@ void policydb_destroy(struct policydb *p) 
	hashtab_map(p->range_tr, range_tr_destroy, NULL);

	hashtab_destroy(p->range_tr);



	if (p->type_attr_map) {

		for (i = 0; i < p->p_types.nprim; i++)

			ebitmap_destroy(&p->type_attr_map[i]);

	if (p->type_attr_map_array) {

		for (i = 0; i < p->p_types.nprim; i++) {

			struct ebitmap *e;



			e = flex_array_get(p->type_attr_map_array, i);

			if (!e)

				continue;

			ebitmap_destroy(e);

		}

		flex_array_free(p->type_attr_map_array);

	}

	kfree(p->type_attr_map);

	ebitmap_destroy(&p->policycaps);

	ebitmap_destroy(&p->permissive_map);
@@ -2257,18 +2264,32 @@ int policydb_read(struct policydb *p, void *fp) 
	if (rc)

		goto bad;



	p->type_attr_map = kmalloc(p->p_types.nprim * sizeof(struct ebitmap), GFP_KERNEL);

	if (!p->type_attr_map)

	rc = -ENOMEM;

	p->type_attr_map_array = flex_array_alloc(sizeof(struct ebitmap),

						  p->p_types.nprim,

						  GFP_KERNEL | __GFP_ZERO);

	if (!p->type_attr_map_array)

		goto bad;



	/* preallocate so we don't have to worry about the put ever failing */

	rc = flex_array_prealloc(p->type_attr_map_array, 0, p->p_types.nprim - 1,

				 GFP_KERNEL | __GFP_ZERO);

	if (rc)

		goto bad;



	for (i = 0; i < p->p_types.nprim; i++) {

		ebitmap_init(&p->type_attr_map[i]);

		struct ebitmap *e = flex_array_get(p->type_attr_map_array, i);



		BUG_ON(!e);

		ebitmap_init(e);

		if (p->policyvers >= POLICYDB_VERSION_AVTAB) {

			if (ebitmap_read(&p->type_attr_map[i], fp))

			rc = ebitmap_read(e, fp);

			if (rc)

				goto bad;

		}

		/* add the type itself as the degenerate case */

		if (ebitmap_set_bit(&p->type_attr_map[i], i, 1))

		rc = ebitmap_set_bit(e, i, 1);

		if (rc)

			goto bad;

	}

security/selinux/ss/policydb.h

+3 −1
Original line number Diff line number Diff line
@@ -24,6 +24,8 @@ 
#ifndef _SS_POLICYDB_H_

#define _SS_POLICYDB_H_



#include <linux/flex_array.h>



#include "symtab.h"

#include "avtab.h"

#include "sidtab.h"
@@ -246,7 +248,7 @@ struct policydb { 
	struct hashtab *range_tr;



	/* type -> attribute reverse mapping */

	struct ebitmap *type_attr_map;

	struct flex_array *type_attr_map_array;



	struct ebitmap policycaps;

security/selinux/ss/services.c

+5 −2
Original line number Diff line number Diff line
@@ -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;

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