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.
Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>
---
security/selinux/ss/policydb.c | 49 ++++++++++++++++++++++++++++++++--------
security/selinux/ss/policydb.h | 4 ++-
security/selinux/ss/services.c | 9 ++++++-
3 files changed, 49 insertions(+), 13 deletions(-)
diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 863d70f..0b9b878 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -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"
@@ -738,11 +739,17 @@ 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);
@@ -2242,19 +2249,35 @@ int policydb_read(struct policydb *p, void *fp)
goto bad;
rc = -ENOMEM;
- p->type_attr_map = kmalloc(p->p_types.nprim * sizeof(struct ebitmap), GFP_KERNEL);
- if (!p->type_attr_map)
+ 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;
+
+ ebitmap_init(&e);
if (p->policyvers >= POLICYDB_VERSION_AVTAB) {
- rc = 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 */
- rc = ebitmap_set_bit(&p->type_attr_map[i], i, 1);
+ rc = ebitmap_set_bit(&e, i, 1);
+ if (rc)
+ goto bad;
+
+ /* should never fail since we preallocated */
+ rc = flex_array_put(p->type_attr_map_array, i, &e,
+ GFP_KERNEL | __GFP_ZERO);
if (rc)
goto bad;
}
@@ -3100,7 +3123,13 @@ int policydb_write(struct policydb *p, void *fp)
return rc;
for (i = 0; i < p->p_types.nprim; i++) {
- rc = ebitmap_write(&p->type_attr_map[i], fp);
+ struct ebitmap *e;
+
+ e = flex_array_get(p->type_attr_map_array, i);
+ if (unlikely(!e))
+ BUG();
+
+ rc = ebitmap_write(e, fp);
if (rc)
return rc;
}
diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h
index 9cbf9df..e013654 100644
--- a/security/selinux/ss/policydb.h
+++ b/security/selinux/ss/policydb.h
@@ -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;
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index a4ac232..20b10bf 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"
@@ -627,8 +628,12 @@ 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);
+ if (unlikely(!sattr))
+ BUG();
+ tattr = flex_array_get(policydb.type_attr_map_array, tcontext->type - 1);
+ if (unlikely(!tattr))
+ BUG();
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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