[linux-2.6-block.git] / net / bridge / br_netfilter_ipv6.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Handle firewalling
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 *	Bart De Schuymer		<bdschuym@pandora.be>
 *
 *	Lennert dedicates this file to Kerstin Wurdinger.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/ip.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/if_pppox.h>
#include <linux/ppp_defs.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_arp.h>
#include <linux/in_route.h>
#include <linux/inetdevice.h>

#include <net/ip.h>
#include <net/ipv6.h>
#include <net/addrconf.h>
#include <net/route.h>
#include <net/netfilter/br_netfilter.h>

#include <linux/uaccess.h>
#include "br_private.h"
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif

/* We only check the length. A bridge shouldn't do any hop-by-hop stuff
 * anyway
 */
static int br_nf_check_hbh_len(struct sk_buff *skb)
{
	unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
	u32 pkt_len;
	const unsigned char *nh = skb_network_header(skb);
	int off = raw - nh;
	int len = (raw[1] + 1) << 3;

	if ((raw + len) - skb->data > skb_headlen(skb))
		goto bad;

	off += 2;
	len -= 2;

	while (len > 0) {
		int optlen = nh[off + 1] + 2;

		switch (nh[off]) {
		case IPV6_TLV_PAD1:
			optlen = 1;
			break;

		case IPV6_TLV_PADN:
			break;

		case IPV6_TLV_JUMBO:
			if (nh[off + 1] != 4 || (off & 3) != 2)
				goto bad;
			pkt_len = ntohl(*(__be32 *)(nh + off + 2));
			if (pkt_len <= IPV6_MAXPLEN ||
			    ipv6_hdr(skb)->payload_len)
				goto bad;
			if (pkt_len > skb->len - sizeof(struct ipv6hdr))
				goto bad;
			if (pskb_trim_rcsum(skb,
					    pkt_len + sizeof(struct ipv6hdr)))
				goto bad;
			nh = skb_network_header(skb);
			break;
		default:
			if (optlen > len)
				goto bad;
			break;
		}
		off += optlen;
		len -= optlen;
	}
	if (len == 0)
		return 0;
bad:
	return -1;
}

int br_validate_ipv6(struct net *net, struct sk_buff *skb)
{
	const struct ipv6hdr *hdr;
	struct inet6_dev *idev = __in6_dev_get(skb->dev);
	u32 pkt_len;
	u8 ip6h_len = sizeof(struct ipv6hdr);

	if (!pskb_may_pull(skb, ip6h_len))
		goto inhdr_error;

	if (skb->len < ip6h_len)
		goto drop;

	hdr = ipv6_hdr(skb);

	if (hdr->version != 6)
		goto inhdr_error;

	pkt_len = ntohs(hdr->payload_len);

	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
		if (pkt_len + ip6h_len > skb->len) {
			__IP6_INC_STATS(net, idev,
					IPSTATS_MIB_INTRUNCATEDPKTS);
			goto drop;
		}
		if (pskb_trim_rcsum(skb, pkt_len + ip6h_len)) {
			__IP6_INC_STATS(net, idev,
					IPSTATS_MIB_INDISCARDS);
			goto drop;
		}
		hdr = ipv6_hdr(skb);
	}
	if (hdr->nexthdr == NEXTHDR_HOP && br_nf_check_hbh_len(skb))
		goto drop;

	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
	/* No IP options in IPv6 header; however it should be
	 * checked if some next headers need special treatment
	 */
	return 0;

inhdr_error:
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
drop:
	return -1;
}

static inline bool
br_nf_ipv6_daddr_was_changed(const struct sk_buff *skb,
			     const struct nf_bridge_info *nf_bridge)
{
	return memcmp(&nf_bridge->ipv6_daddr, &ipv6_hdr(skb)->daddr,
		      sizeof(ipv6_hdr(skb)->daddr)) != 0;
}

/* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables
 * PREROUTING and continue the bridge PRE_ROUTING hook. See comment
 * for br_nf_pre_routing_finish(), same logic is used here but
 * equivalent IPv6 function ip6_route_input() called indirectly.
 */
static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
	struct rtable *rt;
	struct net_device *dev = skb->dev;
	const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();

	nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;

	if (nf_bridge->pkt_otherhost) {
		skb->pkt_type = PACKET_OTHERHOST;
		nf_bridge->pkt_otherhost = false;
	}
	nf_bridge->in_prerouting = 0;
	if (br_nf_ipv6_daddr_was_changed(skb, nf_bridge)) {
		skb_dst_drop(skb);
		v6ops->route_input(skb);

		if (skb_dst(skb)->error) {
			kfree_skb(skb);
			return 0;
		}

		if (skb_dst(skb)->dev == dev) {
			skb->dev = nf_bridge->physindev;
			nf_bridge_update_protocol(skb);
			nf_bridge_push_encap_header(skb);
			br_nf_hook_thresh(NF_BR_PRE_ROUTING,
					  net, sk, skb, skb->dev, NULL,
					  br_nf_pre_routing_finish_bridge);
			return 0;
		}
		ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
		skb->pkt_type = PACKET_HOST;
	} else {
		rt = bridge_parent_rtable(nf_bridge->physindev);
		if (!rt) {
			kfree_skb(skb);
			return 0;
		}
		skb_dst_set_noref(skb, &rt->dst);
	}

	skb->dev = nf_bridge->physindev;
	nf_bridge_update_protocol(skb);
	nf_bridge_push_encap_header(skb);
	br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb,
			  skb->dev, NULL, br_handle_frame_finish);

	return 0;
}

/* Replicate the checks that IPv6 does on packet reception and pass the packet
 * to ip6tables.
 */
unsigned int br_nf_pre_routing_ipv6(void *priv,
				    struct sk_buff *skb,
				    const struct nf_hook_state *state)
{
	struct nf_bridge_info *nf_bridge;

	if (br_validate_ipv6(state->net, skb))
		return NF_DROP;

	nf_bridge = nf_bridge_alloc(skb);
	if (!nf_bridge)
		return NF_DROP;
	if (!setup_pre_routing(skb, state->net))
		return NF_DROP;

	nf_bridge = nf_bridge_info_get(skb);
	nf_bridge->ipv6_daddr = ipv6_hdr(skb)->daddr;

	skb->protocol = htons(ETH_P_IPV6);
	skb->transport_header = skb->network_header + sizeof(struct ipv6hdr);

	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
		skb->dev, NULL,
		br_nf_pre_routing_finish_ipv6);

	return NF_STOLEN;
}
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
230ac490 PNA	2	/*
	3	* Handle firewalling
	4	* Linux ethernet bridge
	5	*
	6	* Authors:
	7	* Lennert Buytenhek <buytenh@gnu.org>
	8	* Bart De Schuymer <bdschuym@pandora.be>
	9	*
230ac490 PNA	10	* Lennert dedicates this file to Kerstin Wurdinger.
	11	*/
	12
	13	#include <linux/module.h>
	14	#include <linux/kernel.h>
	15	#include <linux/slab.h>
	16	#include <linux/ip.h>
	17	#include <linux/netdevice.h>
	18	#include <linux/skbuff.h>
	19	#include <linux/if_arp.h>
	20	#include <linux/if_ether.h>
	21	#include <linux/if_vlan.h>
	22	#include <linux/if_pppox.h>
	23	#include <linux/ppp_defs.h>
	24	#include <linux/netfilter_bridge.h>
	25	#include <linux/netfilter_ipv4.h>
	26	#include <linux/netfilter_ipv6.h>
	27	#include <linux/netfilter_arp.h>
	28	#include <linux/in_route.h>
	29	#include <linux/inetdevice.h>
	30
	31	#include <net/ip.h>
	32	#include <net/ipv6.h>
	33	#include <net/addrconf.h>
	34	#include <net/route.h>
	35	#include <net/netfilter/br_netfilter.h>
	36
7c0f6ba6	37	#include <linux/uaccess.h>
230ac490 PNA	38	#include "br_private.h"
	39	#ifdef CONFIG_SYSCTL
	40	#include <linux/sysctl.h>
	41	#endif
	42
	43	/* We only check the length. A bridge shouldn't do any hop-by-hop stuff
	44	* anyway
	45	*/
	46	static int br_nf_check_hbh_len(struct sk_buff *skb)
	47	{
	48	unsigned char raw = (u8 )(ipv6_hdr(skb) + 1);
	49	u32 pkt_len;
	50	const unsigned char *nh = skb_network_header(skb);
	51	int off = raw - nh;
	52	int len = (raw[1] + 1) << 3;
	53
	54	if ((raw + len) - skb->data > skb_headlen(skb))
	55	goto bad;
	56
	57	off += 2;
	58	len -= 2;
	59
	60	while (len > 0) {
	61	int optlen = nh[off + 1] + 2;
	62
	63	switch (nh[off]) {
	64	case IPV6_TLV_PAD1:
	65	optlen = 1;
	66	break;
	67
	68	case IPV6_TLV_PADN:
	69	break;
	70
	71	case IPV6_TLV_JUMBO:
	72	if (nh[off + 1] != 4 \|\| (off & 3) != 2)
	73	goto bad;
	74	pkt_len = ntohl((__be32 )(nh + off + 2));
	75	if (pkt_len <= IPV6_MAXPLEN \|\|
	76	ipv6_hdr(skb)->payload_len)
	77	goto bad;
	78	if (pkt_len > skb->len - sizeof(struct ipv6hdr))
	79	goto bad;
	80	if (pskb_trim_rcsum(skb,
	81	pkt_len + sizeof(struct ipv6hdr)))
	82	goto bad;
	83	nh = skb_network_header(skb);
	84	break;
	85	default:
	86	if (optlen > len)
	87	goto bad;
	88	break;
	89	}
	90	off += optlen;
	91	len -= optlen;
	92	}
	93	if (len == 0)
	94	return 0;
	95	bad:
	96	return -1;
	97	}
	98
c1444c63	99	int br_validate_ipv6(struct net net, struct sk_buff skb)
230ac490 PNA	100	{
230ac490 PNA	101	const struct ipv6hdr *hdr;
86e89718	102	struct inet6_dev *idev = __in6_dev_get(skb->dev);
230ac490 PNA	103	u32 pkt_len;
	104	u8 ip6h_len = sizeof(struct ipv6hdr);
	105
	106	if (!pskb_may_pull(skb, ip6h_len))
	107	goto inhdr_error;
	108
	109	if (skb->len < ip6h_len)
	110	goto drop;
	111
	112	hdr = ipv6_hdr(skb);
	113
	114	if (hdr->version != 6)
	115	goto inhdr_error;
	116
	117	pkt_len = ntohs(hdr->payload_len);
	118
	119	if (pkt_len \|\| hdr->nexthdr != NEXTHDR_HOP) {
	120	if (pkt_len + ip6h_len > skb->len) {
1d015503 ED	121	__IP6_INC_STATS(net, idev,
1d015503 ED	122	IPSTATS_MIB_INTRUNCATEDPKTS);
230ac490 PNA	123	goto drop;
	124	}
	125	if (pskb_trim_rcsum(skb, pkt_len + ip6h_len)) {
1d015503 ED	126	__IP6_INC_STATS(net, idev,
1d015503 ED	127	IPSTATS_MIB_INDISCARDS);
230ac490 PNA	128	goto drop;
230ac490 PNA	129	}
6c57f045	130	hdr = ipv6_hdr(skb);
230ac490 PNA	131	}
	132	if (hdr->nexthdr == NEXTHDR_HOP && br_nf_check_hbh_len(skb))
	133	goto drop;
	134
	135	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
	136	/* No IP options in IPv6 header; however it should be
	137	* checked if some next headers need special treatment
	138	*/
	139	return 0;
	140
	141	inhdr_error:
1d015503	142	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
230ac490 PNA	143	drop:
	144	return -1;
	145	}
	146
	147	static inline bool
	148	br_nf_ipv6_daddr_was_changed(const struct sk_buff *skb,
	149	const struct nf_bridge_info *nf_bridge)
	150	{
	151	return memcmp(&nf_bridge->ipv6_daddr, &ipv6_hdr(skb)->daddr,
	152	sizeof(ipv6_hdr(skb)->daddr)) != 0;
	153	}
	154
	155	/* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables
	156	* PREROUTING and continue the bridge PRE_ROUTING hook. See comment
	157	* for br_nf_pre_routing_finish(), same logic is used here but
	158	* equivalent IPv6 function ip6_route_input() called indirectly.
	159	*/
0c4b51f0	160	static int br_nf_pre_routing_finish_ipv6(struct net net, struct sock sk, struct sk_buff *skb)
230ac490 PNA	161	{
	162	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
	163	struct rtable *rt;
	164	struct net_device *dev = skb->dev;
	165	const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
	166
	167	nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
	168
	169	if (nf_bridge->pkt_otherhost) {
	170	skb->pkt_type = PACKET_OTHERHOST;
	171	nf_bridge->pkt_otherhost = false;
	172	}
72b1e5e4	173	nf_bridge->in_prerouting = 0;
230ac490 PNA	174	if (br_nf_ipv6_daddr_was_changed(skb, nf_bridge)) {
	175	skb_dst_drop(skb);
	176	v6ops->route_input(skb);
	177
	178	if (skb_dst(skb)->error) {
	179	kfree_skb(skb);
	180	return 0;
	181	}
	182
	183	if (skb_dst(skb)->dev == dev) {
	184	skb->dev = nf_bridge->physindev;
	185	nf_bridge_update_protocol(skb);
	186	nf_bridge_push_encap_header(skb);
c5136b15 FW	187	br_nf_hook_thresh(NF_BR_PRE_ROUTING,
	188	net, sk, skb, skb->dev, NULL,
	189	br_nf_pre_routing_finish_bridge);
230ac490 PNA	190	return 0;
	191	}
	192	ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
	193	skb->pkt_type = PACKET_HOST;
	194	} else {
	195	rt = bridge_parent_rtable(nf_bridge->physindev);
	196	if (!rt) {
	197	kfree_skb(skb);
	198	return 0;
	199	}
	200	skb_dst_set_noref(skb, &rt->dst);
	201	}
	202
	203	skb->dev = nf_bridge->physindev;
	204	nf_bridge_update_protocol(skb);
	205	nf_bridge_push_encap_header(skb);
c5136b15 FW	206	br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb,
c5136b15 FW	207	skb->dev, NULL, br_handle_frame_finish);
230ac490 PNA	208
	209	return 0;
	210	}
	211
	212	/* Replicate the checks that IPv6 does on packet reception and pass the packet
	213	* to ip6tables.
	214	*/
06198b34	215	unsigned int br_nf_pre_routing_ipv6(void *priv,
230ac490 PNA	216	struct sk_buff *skb,
	217	const struct nf_hook_state *state)
	218	{
	219	struct nf_bridge_info *nf_bridge;
	220
c1444c63	221	if (br_validate_ipv6(state->net, skb))
230ac490 PNA	222	return NF_DROP;
230ac490 PNA	223
de8bda1d FW	224	nf_bridge = nf_bridge_alloc(skb);
de8bda1d FW	225	if (!nf_bridge)
230ac490	226	return NF_DROP;
ff6d090d	227	if (!setup_pre_routing(skb, state->net))
230ac490 PNA	228	return NF_DROP;
	229
	230	nf_bridge = nf_bridge_info_get(skb);
	231	nf_bridge->ipv6_daddr = ipv6_hdr(skb)->daddr;
	232
	233	skb->protocol = htons(ETH_P_IPV6);
e166e4fd XL	234	skb->transport_header = skb->network_header + sizeof(struct ipv6hdr);
e166e4fd XL	235
29a26a56	236	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
230ac490 PNA	237	skb->dev, NULL,
	238	br_nf_pre_routing_finish_ipv6);
	239
	240	return NF_STOLEN;
	241	}