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");