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Commit 590bdf7f authored by Dmitry Mishin's avatar Dmitry Mishin Committed by David S. Miller
Browse files

[NETFILTER]: Missed and reordered checks in {arp,ip,ip6}_tables 



There is a number of issues in parsing user-provided table in
translate_table(). Malicious user with CAP_NET_ADMIN may crash system by
passing special-crafted table to the *_tables.

The first issue is that mark_source_chains() function is called before entry
content checks. In case of standard target, mark_source_chains() function
uses t->verdict field in order to determine new position. But the check, that
this field leads no further, than the table end, is in check_entry(), which
is called later, than mark_source_chains().

The second issue, that there is no check that target_offset points inside
entry. If so, *_ITERATE_MATCH macro will follow further, than the entry
ends. As a result, we'll have oops or memory disclosure.

And the third issue, that there is no check that the target is completely
inside entry. Results are the same, as in previous issue.

Signed-off-by: default avatarDmitry Mishin <dim@openvz.org>
Acked-by: default avatarKirill Korotaev <dev@openvz.org>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 844dc7c8

net/ipv4/netfilter/arp_tables.c

+16 −9
Original line number Diff line number Diff line
@@ -466,7 +466,13 @@ static inline int check_entry(struct arpt_entry *e, const char *name, unsigned i 
		return -EINVAL;

	}



	if (e->target_offset + sizeof(struct arpt_entry_target) > e->next_offset)

		return -EINVAL;



	t = arpt_get_target(e);

	if (e->target_offset + t->u.target_size > e->next_offset)

		return -EINVAL;



	target = try_then_request_module(xt_find_target(NF_ARP, t->u.user.name,

							t->u.user.revision),

					 "arpt_%s", t->u.user.name);
@@ -621,20 +627,18 @@ static int translate_table(const char *name, 
		}

	}



	if (!mark_source_chains(newinfo, valid_hooks, entry0)) {

		duprintf("Looping hook\n");

		return -ELOOP;

	}



	/* Finally, each sanity check must pass */

	i = 0;

	ret = ARPT_ENTRY_ITERATE(entry0, newinfo->size,

				 check_entry, name, size, &i);



	if (ret != 0) {

		ARPT_ENTRY_ITERATE(entry0, newinfo->size,

				   cleanup_entry, &i);

		return ret;

	if (ret != 0)

		goto cleanup;



	ret = -ELOOP;

	if (!mark_source_chains(newinfo, valid_hooks, entry0)) {

		duprintf("Looping hook\n");

		goto cleanup;

	}



	/* And one copy for every other CPU */
@@ -643,6 +647,9 @@ static int translate_table(const char *name, 
			memcpy(newinfo->entries[i], entry0, newinfo->size);

	}



	return 0;

cleanup:

	ARPT_ENTRY_ITERATE(entry0, newinfo->size, cleanup_entry, &i);

	return ret;

}

net/ipv4/netfilter/ip_tables.c

+22 −8
Original line number Diff line number Diff line
@@ -547,12 +547,18 @@ check_entry(struct ipt_entry *e, const char *name, unsigned int size, 
		return -EINVAL;

	}



	if (e->target_offset + sizeof(struct ipt_entry_target) > e->next_offset)

		return -EINVAL;



	j = 0;

	ret = IPT_MATCH_ITERATE(e, check_match, name, &e->ip, e->comefrom, &j);

	if (ret != 0)

		goto cleanup_matches;



	t = ipt_get_target(e);

	ret = -EINVAL;

	if (e->target_offset + t->u.target_size > e->next_offset)

			goto cleanup_matches;

	target = try_then_request_module(xt_find_target(AF_INET,

						     t->u.user.name,

						     t->u.user.revision),
@@ -712,19 +718,17 @@ translate_table(const char *name, 
		}

	}



	if (!mark_source_chains(newinfo, valid_hooks, entry0))

		return -ELOOP;



	/* Finally, each sanity check must pass */

	i = 0;

	ret = IPT_ENTRY_ITERATE(entry0, newinfo->size,

				check_entry, name, size, &i);



	if (ret != 0) {

		IPT_ENTRY_ITERATE(entry0, newinfo->size,

				  cleanup_entry, &i);

		return ret;

	}

	if (ret != 0)

		goto cleanup;



	ret = -ELOOP;

	if (!mark_source_chains(newinfo, valid_hooks, entry0))

		goto cleanup;



	/* And one copy for every other CPU */

	for_each_possible_cpu(i) {
@@ -732,6 +736,9 @@ translate_table(const char *name, 
			memcpy(newinfo->entries[i], entry0, newinfo->size);

	}



	return 0;

cleanup:

	IPT_ENTRY_ITERATE(entry0, newinfo->size, cleanup_entry, &i);

	return ret;

}
@@ -1463,6 +1470,10 @@ check_compat_entry_size_and_hooks(struct ipt_entry *e, 
		return -EINVAL;

	}



	if (e->target_offset + sizeof(struct compat_xt_entry_target) >

								e->next_offset)

		return -EINVAL;



	off = 0;

	entry_offset = (void *)e - (void *)base;

	j = 0;
@@ -1472,6 +1483,9 @@ check_compat_entry_size_and_hooks(struct ipt_entry *e, 
		goto cleanup_matches;



	t = ipt_get_target(e);

	ret = -EINVAL;

	if (e->target_offset + t->u.target_size > e->next_offset)

			goto cleanup_matches;

	target = try_then_request_module(xt_find_target(AF_INET,

						     t->u.user.name,

						     t->u.user.revision),

net/ipv6/netfilter/ip6_tables.c

+16 −8
Original line number Diff line number Diff line
@@ -586,12 +586,19 @@ check_entry(struct ip6t_entry *e, const char *name, unsigned int size, 
		return -EINVAL;

	}



	if (e->target_offset + sizeof(struct ip6t_entry_target) >

								e->next_offset)

		return -EINVAL;



	j = 0;

	ret = IP6T_MATCH_ITERATE(e, check_match, name, &e->ipv6, e->comefrom, &j);

	if (ret != 0)

		goto cleanup_matches;



	t = ip6t_get_target(e);

	ret = -EINVAL;

	if (e->target_offset + t->u.target_size > e->next_offset)

			goto cleanup_matches;

	target = try_then_request_module(xt_find_target(AF_INET6,

							t->u.user.name,

							t->u.user.revision),
@@ -751,19 +758,17 @@ translate_table(const char *name, 
		}

	}



	if (!mark_source_chains(newinfo, valid_hooks, entry0))

		return -ELOOP;



	/* Finally, each sanity check must pass */

	i = 0;

	ret = IP6T_ENTRY_ITERATE(entry0, newinfo->size,

				check_entry, name, size, &i);



	if (ret != 0) {

		IP6T_ENTRY_ITERATE(entry0, newinfo->size,

				  cleanup_entry, &i);

		return ret;

	}

	if (ret != 0)

		goto cleanup;



	ret = -ELOOP;

	if (!mark_source_chains(newinfo, valid_hooks, entry0))

		goto cleanup;



	/* And one copy for every other CPU */

	for_each_possible_cpu(i) {
@@ -771,6 +776,9 @@ translate_table(const char *name, 
			memcpy(newinfo->entries[i], entry0, newinfo->size);

	}



	return 0;

cleanup:

	IP6T_ENTRY_ITERATE(entry0, newinfo->size, cleanup_entry, &i);

	return ret;

}