SELinux: add more validity checks on policy load
Add more validity checks at policy load time to reject malformed
policies and prevent subsequent out-of-range indexing when in permissive
mode. Resolves the NULL pointer dereference reported in
https://bugzilla.redhat.com/show_bug.cgi?id=357541.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c
index 9a11dea..fb5d70a 100644
--- a/security/selinux/ss/mls.c
+++ b/security/selinux/ss/mls.c
@@ -157,49 +157,55 @@
return;
}
+int mls_level_isvalid(struct policydb *p, struct mls_level *l)
+{
+ struct level_datum *levdatum;
+ struct ebitmap_node *node;
+ int i;
+
+ if (!l->sens || l->sens > p->p_levels.nprim)
+ return 0;
+ levdatum = hashtab_search(p->p_levels.table,
+ p->p_sens_val_to_name[l->sens - 1]);
+ if (!levdatum)
+ return 0;
+
+ ebitmap_for_each_positive_bit(&l->cat, node, i) {
+ if (i > p->p_cats.nprim)
+ return 0;
+ if (!ebitmap_get_bit(&levdatum->level->cat, i)) {
+ /*
+ * Category may not be associated with
+ * sensitivity.
+ */
+ return 0;
+ }
+ }
+
+ return 1;
+}
+
+int mls_range_isvalid(struct policydb *p, struct mls_range *r)
+{
+ return (mls_level_isvalid(p, &r->level[0]) &&
+ mls_level_isvalid(p, &r->level[1]) &&
+ mls_level_dom(&r->level[1], &r->level[0]));
+}
+
/*
* Return 1 if the MLS fields in the security context
* structure `c' are valid. Return 0 otherwise.
*/
int mls_context_isvalid(struct policydb *p, struct context *c)
{
- struct level_datum *levdatum;
struct user_datum *usrdatum;
- struct ebitmap_node *node;
- int i, l;
if (!selinux_mls_enabled)
return 1;
- /*
- * MLS range validity checks: high must dominate low, low level must
- * be valid (category set <-> sensitivity check), and high level must
- * be valid (category set <-> sensitivity check)
- */
- if (!mls_level_dom(&c->range.level[1], &c->range.level[0]))
- /* High does not dominate low. */
+ if (!mls_range_isvalid(p, &c->range))
return 0;
- for (l = 0; l < 2; l++) {
- if (!c->range.level[l].sens || c->range.level[l].sens > p->p_levels.nprim)
- return 0;
- levdatum = hashtab_search(p->p_levels.table,
- p->p_sens_val_to_name[c->range.level[l].sens - 1]);
- if (!levdatum)
- return 0;
-
- ebitmap_for_each_positive_bit(&c->range.level[l].cat, node, i) {
- if (i > p->p_cats.nprim)
- return 0;
- if (!ebitmap_get_bit(&levdatum->level->cat, i))
- /*
- * Category may not be associated with
- * sensitivity in low level.
- */
- return 0;
- }
- }
-
if (c->role == OBJECT_R_VAL)
return 1;