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/avtab.c b/security/selinux/ss/avtab.c
index 7551af1..9e70a16 100644
--- a/security/selinux/ss/avtab.c
+++ b/security/selinux/ss/avtab.c
@@ -325,7 +325,7 @@
AVTAB_MEMBER
};
-int avtab_read_item(void *fp, u32 vers, struct avtab *a,
+int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
int (*insertf)(struct avtab *a, struct avtab_key *k,
struct avtab_datum *d, void *p),
void *p)
@@ -333,10 +333,11 @@
__le16 buf16[4];
u16 enabled;
__le32 buf32[7];
- u32 items, items2, val;
+ u32 items, items2, val, vers = pol->policyvers;
struct avtab_key key;
struct avtab_datum datum;
int i, rc;
+ unsigned set;
memset(&key, 0, sizeof(struct avtab_key));
memset(&datum, 0, sizeof(struct avtab_datum));
@@ -420,12 +421,35 @@
key.target_class = le16_to_cpu(buf16[items++]);
key.specified = le16_to_cpu(buf16[items++]);
+ if (!policydb_type_isvalid(pol, key.source_type) ||
+ !policydb_type_isvalid(pol, key.target_type) ||
+ !policydb_class_isvalid(pol, key.target_class)) {
+ printk(KERN_WARNING "security: avtab: invalid type or class\n");
+ return -1;
+ }
+
+ set = 0;
+ for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
+ if (key.specified & spec_order[i])
+ set++;
+ }
+ if (!set || set > 1) {
+ printk(KERN_WARNING
+ "security: avtab: more than one specifier\n");
+ return -1;
+ }
+
rc = next_entry(buf32, fp, sizeof(u32));
if (rc < 0) {
printk("security: avtab: truncated entry\n");
return -1;
}
datum.data = le32_to_cpu(*buf32);
+ if ((key.specified & AVTAB_TYPE) &&
+ !policydb_type_isvalid(pol, datum.data)) {
+ printk(KERN_WARNING "security: avtab: invalid type\n");
+ return -1;
+ }
return insertf(a, &key, &datum, p);
}
@@ -435,7 +459,7 @@
return avtab_insert(a, k, d);
}
-int avtab_read(struct avtab *a, void *fp, u32 vers)
+int avtab_read(struct avtab *a, void *fp, struct policydb *pol)
{
int rc;
__le32 buf[1];
@@ -459,7 +483,7 @@
goto bad;
for (i = 0; i < nel; i++) {
- rc = avtab_read_item(fp,vers, a, avtab_insertf, NULL);
+ rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL);
if (rc) {
if (rc == -ENOMEM)
printk(KERN_ERR "security: avtab: out of memory\n");
diff --git a/security/selinux/ss/avtab.h b/security/selinux/ss/avtab.h
index d8edf8c..8da6a84 100644
--- a/security/selinux/ss/avtab.h
+++ b/security/selinux/ss/avtab.h
@@ -64,12 +64,13 @@
void avtab_destroy(struct avtab *h);
void avtab_hash_eval(struct avtab *h, char *tag);
-int avtab_read_item(void *fp, uint32_t vers, struct avtab *a,
+struct policydb;
+int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
int (*insert)(struct avtab *a, struct avtab_key *k,
struct avtab_datum *d, void *p),
void *p);
-int avtab_read(struct avtab *a, void *fp, u32 vers);
+int avtab_read(struct avtab *a, void *fp, struct policydb *pol);
struct avtab_node *avtab_insert_nonunique(struct avtab *h, struct avtab_key *key,
struct avtab_datum *datum);
diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c
index 45b93a8..50ad85d 100644
--- a/security/selinux/ss/conditional.c
+++ b/security/selinux/ss/conditional.c
@@ -362,7 +362,8 @@
data.head = NULL;
data.tail = NULL;
for (i = 0; i < len; i++) {
- rc = avtab_read_item(fp, p->policyvers, &p->te_cond_avtab, cond_insertf, &data);
+ rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf,
+ &data);
if (rc)
return rc;
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;
diff --git a/security/selinux/ss/mls.h b/security/selinux/ss/mls.h
index 096d1b4..ab53663 100644
--- a/security/selinux/ss/mls.h
+++ b/security/selinux/ss/mls.h
@@ -27,6 +27,8 @@
int mls_compute_context_len(struct context *context);
void mls_sid_to_context(struct context *context, char **scontext);
int mls_context_isvalid(struct policydb *p, struct context *c);
+int mls_range_isvalid(struct policydb *p, struct mls_range *r);
+int mls_level_isvalid(struct policydb *p, struct mls_level *l);
int mls_context_to_sid(char oldc,
char **scontext,
diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 539828b..b582aae 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -713,6 +713,27 @@
return rc;
}
+int policydb_class_isvalid(struct policydb *p, unsigned int class)
+{
+ if (!class || class > p->p_classes.nprim)
+ return 0;
+ return 1;
+}
+
+int policydb_role_isvalid(struct policydb *p, unsigned int role)
+{
+ if (!role || role > p->p_roles.nprim)
+ return 0;
+ return 1;
+}
+
+int policydb_type_isvalid(struct policydb *p, unsigned int type)
+{
+ if (!type || type > p->p_types.nprim)
+ return 0;
+ return 1;
+}
+
/*
* Return 1 if the fields in the security context
* structure `c' are valid. Return 0 otherwise.
@@ -1260,6 +1281,7 @@
"categories\n");
goto bad;
}
+
return 0;
bad:
@@ -1563,7 +1585,7 @@
p->symtab[i].nprim = nprim;
}
- rc = avtab_read(&p->te_avtab, fp, p->policyvers);
+ rc = avtab_read(&p->te_avtab, fp, p);
if (rc)
goto bad;
@@ -1595,6 +1617,12 @@
tr->role = le32_to_cpu(buf[0]);
tr->type = le32_to_cpu(buf[1]);
tr->new_role = le32_to_cpu(buf[2]);
+ if (!policydb_role_isvalid(p, tr->role) ||
+ !policydb_type_isvalid(p, tr->type) ||
+ !policydb_role_isvalid(p, tr->new_role)) {
+ rc = -EINVAL;
+ goto bad;
+ }
ltr = tr;
}
@@ -1619,6 +1647,11 @@
goto bad;
ra->role = le32_to_cpu(buf[0]);
ra->new_role = le32_to_cpu(buf[1]);
+ if (!policydb_role_isvalid(p, ra->role) ||
+ !policydb_role_isvalid(p, ra->new_role)) {
+ rc = -EINVAL;
+ goto bad;
+ }
lra = ra;
}
@@ -1872,9 +1905,19 @@
rt->target_class = le32_to_cpu(buf[0]);
} else
rt->target_class = SECCLASS_PROCESS;
+ if (!policydb_type_isvalid(p, rt->source_type) ||
+ !policydb_type_isvalid(p, rt->target_type) ||
+ !policydb_class_isvalid(p, rt->target_class)) {
+ rc = -EINVAL;
+ goto bad;
+ }
rc = mls_read_range_helper(&rt->target_range, fp);
if (rc)
goto bad;
+ if (!mls_range_isvalid(p, &rt->target_range)) {
+ printk(KERN_WARNING "security: rangetrans: invalid range\n");
+ goto bad;
+ }
lrt = rt;
}
}
diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h
index 844d310..ed6fc68 100644
--- a/security/selinux/ss/policydb.h
+++ b/security/selinux/ss/policydb.h
@@ -251,6 +251,9 @@
extern void policydb_destroy(struct policydb *p);
extern int policydb_load_isids(struct policydb *p, struct sidtab *s);
extern int policydb_context_isvalid(struct policydb *p, struct context *c);
+extern int policydb_class_isvalid(struct policydb *p, unsigned int class);
+extern int policydb_type_isvalid(struct policydb *p, unsigned int type);
+extern int policydb_role_isvalid(struct policydb *p, unsigned int role);
extern int policydb_read(struct policydb *p, void *fp);
#define PERM_SYMTAB_SIZE 32