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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>
This commit is contained in:
Eric Paris 2010-07-29 23:02:34 -04:00 committed by James Morris
parent 016d825fe0
commit 6371dcd36f
3 changed files with 39 additions and 13 deletions
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41
security/selinux/ss/policydb.c
View File

@ -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);
@ -2257,19 +2264,33 @@ 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))
goto bad;
rc = ebitmap_set_bit(e, i, 1);
if (rc)
goto bad;
}
rc = policydb_bounds_sanity_check(p);

4
security/selinux/ss/policydb.h
View File

@ -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;

7
security/selinux/ss/services.c
View File

@ -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;