@@ -239,7 +239,7 @@ void xt_unregister_match(struct xt_match *target);
int xt_register_matches(struct xt_match *match, unsigned int n);
void xt_unregister_matches(struct xt_match *match, unsigned int n);
-int xt_check_entry_offsets(const void *base,
+int xt_check_entry_offsets(const void *base, const char *elems,
unsigned int target_offset,
unsigned int next_offset);
@@ -435,7 +435,7 @@ void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
unsigned int *size);
int xt_compat_target_to_user(const struct xt_entry_target *t,
void __user **dstptr, unsigned int *size);
-int xt_compat_check_entry_offsets(const void *base,
+int xt_compat_check_entry_offsets(const void *base, const char *elems,
unsigned int target_offset,
unsigned int next_offset);
@@ -592,7 +592,8 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
if (!arp_checkentry(&e->arp))
return -EINVAL;
- err = xt_check_entry_offsets(e, e->target_offset, e->next_offset);
+ err = xt_check_entry_offsets(e, e->elems, e->target_offset,
+ e->next_offset);
if (err)
return err;
@@ -1257,7 +1258,7 @@ check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
if (!arp_checkentry(&e->arp))
return -EINVAL;
- ret = xt_compat_check_entry_offsets(e, e->target_offset,
+ ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
e->next_offset);
if (ret)
return ret;
@@ -753,7 +753,8 @@ check_entry_size_and_hooks(struct ipt_entry *e,
if (!ip_checkentry(&e->ip))
return -EINVAL;
- err = xt_check_entry_offsets(e, e->target_offset, e->next_offset);
+ err = xt_check_entry_offsets(e, e->elems, e->target_offset,
+ e->next_offset);
if (err)
return err;
@@ -1523,7 +1524,7 @@ check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
if (!ip_checkentry(&e->ip))
return -EINVAL;
- ret = xt_compat_check_entry_offsets(e,
+ ret = xt_compat_check_entry_offsets(e, e->elems,
e->target_offset, e->next_offset);
if (ret)
return ret;
@@ -764,7 +764,8 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
if (!ip6_checkentry(&e->ipv6))
return -EINVAL;
- err = xt_check_entry_offsets(e, e->target_offset, e->next_offset);
+ err = xt_check_entry_offsets(e, e->elems, e->target_offset,
+ e->next_offset);
if (err)
return err;
@@ -1535,7 +1536,7 @@ check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e,
if (!ip6_checkentry(&e->ipv6))
return -EINVAL;
- ret = xt_compat_check_entry_offsets(e,
+ ret = xt_compat_check_entry_offsets(e, e->elems,
e->target_offset, e->next_offset);
if (ret)
return ret;
@@ -549,14 +549,17 @@ struct compat_xt_standard_target {
compat_uint_t verdict;
};
-/* see xt_check_entry_offsets */
-int xt_compat_check_entry_offsets(const void *base,
+int xt_compat_check_entry_offsets(const void *base, const char *elems,
unsigned int target_offset,
unsigned int next_offset)
{
+ long size_of_base_struct = elems - (const char *)base;
const struct compat_xt_entry_target *t;
const char *e = base;
+ if (target_offset < size_of_base_struct)
+ return -EINVAL;
+
if (target_offset + sizeof(*t) > next_offset)
return -EINVAL;
@@ -580,12 +583,16 @@ EXPORT_SYMBOL(xt_compat_check_entry_offsets);
* xt_check_entry_offsets - validate arp/ip/ip6t_entry
*
* @base: pointer to arp/ip/ip6t_entry
+ * @elems: pointer to first xt_entry_match, i.e. ip(6)t_entry->elems
* @target_offset: the arp/ip/ip6_t->target_offset
* @next_offset: the arp/ip/ip6_t->next_offset
*
* validates that target_offset and next_offset are sane.
* Also see xt_compat_check_entry_offsets for CONFIG_COMPAT version.
*
+ * This function does not validate the targets or matches themselves, it
+ * only tests that all the offsets and sizes are correct.
+ *
* The arp/ip/ip6t_entry structure @base must have passed following tests:
* - it must point to a valid memory location
* - base to base + next_offset must be accessible, i.e. not exceed allocated
@@ -594,12 +601,18 @@ EXPORT_SYMBOL(xt_compat_check_entry_offsets);
* Return: 0 on success, negative errno on failure.
*/
int xt_check_entry_offsets(const void *base,
+ const char *elems,
unsigned int target_offset,
unsigned int next_offset)
{
+ long size_of_base_struct = elems - (const char *)base;
const struct xt_entry_target *t;
const char *e = base;
+ /* target start is within the ip/ip6/arpt_entry struct */
+ if (target_offset < size_of_base_struct)
+ return -EINVAL;
+
if (target_offset + sizeof(*t) > next_offset)
return -EINVAL;