[deliverable/linux.git] / net / ipv4 / xfrm4_input.c

/*
 * xfrm4_input.c
 *
 * Changes:
 *	YOSHIFUJI Hideaki @USAGI
 *		Split up af-specific portion
 *	Derek Atkins <derek@ihtfp.com>
 *		Add Encapsulation support
 *
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <net/ip.h>
#include <net/xfrm.h>

int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
{
	return xfrm4_extract_header(skb);
}

#ifdef CONFIG_NETFILTER
static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
{
	if (skb->dst == NULL) {
		const struct iphdr *iph = ip_hdr(skb);

		if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
				   skb->dev))
			goto drop;
	}
	return dst_input(skb);
drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}
#endif

int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
		    int encap_type)
{
	XFRM_SPI_SKB_CB(skb)->nhoff = offsetof(struct iphdr, protocol);
	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
	return xfrm_input(skb, nexthdr, spi, encap_type);
}
EXPORT_SYMBOL(xfrm4_rcv_encap);

int xfrm4_transport_finish(struct sk_buff *skb, int async)
{
#ifdef CONFIG_NETFILTER
	__skb_push(skb, skb->data - skb_network_header(skb));
	ip_hdr(skb)->tot_len = htons(skb->len);
	ip_send_check(ip_hdr(skb));

	NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
		xfrm4_rcv_encap_finish);
	return 0;
#else
	return -ip_hdr(skb)->protocol;
#endif
}

/* If it's a keepalive packet, then just eat it.
 * If it's an encapsulated packet, then pass it to the
 * IPsec xfrm input.
 * Returns 0 if skb passed to xfrm or was dropped.
 * Returns >0 if skb should be passed to UDP.
 * Returns <0 if skb should be resubmitted (-ret is protocol)
 */
int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
{
	struct udp_sock *up = udp_sk(sk);
	struct udphdr *uh;
	struct iphdr *iph;
	int iphlen, len;
	int ret;

	__u8 *udpdata;
	__be32 *udpdata32;
	__u16 encap_type = up->encap_type;

	/* if this is not encapsulated socket, then just return now */
	if (!encap_type)
		return 1;

	/* If this is a paged skb, make sure we pull up
	 * whatever data we need to look at. */
	len = skb->len - sizeof(struct udphdr);
	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
		return 1;

	/* Now we can get the pointers */
	uh = udp_hdr(skb);
	udpdata = (__u8 *)uh + sizeof(struct udphdr);
	udpdata32 = (__be32 *)udpdata;

	switch (encap_type) {
	default:
	case UDP_ENCAP_ESPINUDP:
		/* Check if this is a keepalive packet.  If so, eat it. */
		if (len == 1 && udpdata[0] == 0xff) {
			goto drop;
		} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
			/* ESP Packet without Non-ESP header */
			len = sizeof(struct udphdr);
		} else
			/* Must be an IKE packet.. pass it through */
			return 1;
		break;
	case UDP_ENCAP_ESPINUDP_NON_IKE:
		/* Check if this is a keepalive packet.  If so, eat it. */
		if (len == 1 && udpdata[0] == 0xff) {
			goto drop;
		} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
			   udpdata32[0] == 0 && udpdata32[1] == 0) {

			/* ESP Packet with Non-IKE marker */
			len = sizeof(struct udphdr) + 2 * sizeof(u32);
		} else
			/* Must be an IKE packet.. pass it through */
			return 1;
		break;
	}

	/* At this point we are sure that this is an ESPinUDP packet,
	 * so we need to remove 'len' bytes from the packet (the UDP
	 * header and optional ESP marker bytes) and then modify the
	 * protocol to ESP, and then call into the transform receiver.
	 */
	if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
		goto drop;

	/* Now we can update and verify the packet length... */
	iph = ip_hdr(skb);
	iphlen = iph->ihl << 2;
	iph->tot_len = htons(ntohs(iph->tot_len) - len);
	if (skb->len < iphlen + len) {
		/* packet is too small!?! */
		goto drop;
	}

	/* pull the data buffer up to the ESP header and set the
	 * transport header to point to ESP.  Keep UDP on the stack
	 * for later.
	 */
	__skb_pull(skb, len);
	skb_reset_transport_header(skb);

	/* process ESP */
	ret = xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
	return ret;

drop:
	kfree_skb(skb);
	return 0;
}

int xfrm4_rcv(struct sk_buff *skb)
{
	return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
}

EXPORT_SYMBOL(xfrm4_rcv);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* xfrm4_input.c
	3	*
	4	* Changes:
	5	* YOSHIFUJI Hideaki @USAGI
	6	* Split up af-specific portion
	7	* Derek Atkins <derek@ihtfp.com>
	8	* Add Encapsulation support
e905a9ed	9	*
1da177e4 LT	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/string.h>
b05e1066 PM	14	#include <linux/netfilter.h>
b05e1066 PM	15	#include <linux/netfilter_ipv4.h>
1da177e4 LT	16	#include <net/ip.h>
	17	#include <net/xfrm.h>
	18
227620e2 HX	19	int xfrm4_extract_input(struct xfrm_state x, struct sk_buff skb)
	20	{
	21	return xfrm4_extract_header(skb);
	22	}
	23
b05e1066 PM	24	#ifdef CONFIG_NETFILTER
	25	static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
	26	{
b05e1066	27	if (skb->dst == NULL) {
eddc9ec5 ACM	28	const struct iphdr *iph = ip_hdr(skb);
eddc9ec5 ACM	29
b05e1066	30	if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
e905a9ed	31	skb->dev))
b05e1066 PM	32	goto drop;
	33	}
	34	return dst_input(skb);
	35	drop:
	36	kfree_skb(skb);
	37	return NET_RX_DROP;
	38	}
	39	#endif
	40
c4541b41 HX	41	int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
c4541b41 HX	42	int encap_type)
1da177e4	43	{
716062fd HX	44	XFRM_SPI_SKB_CB(skb)->nhoff = offsetof(struct iphdr, protocol);
	45	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
	46	return xfrm_input(skb, nexthdr, spi, encap_type);
	47	}
	48	EXPORT_SYMBOL(xfrm4_rcv_encap);
b05e1066	49
716062fd HX	50	int xfrm4_transport_finish(struct sk_buff *skb, int async)
716062fd HX	51	{
b05e1066	52	#ifdef CONFIG_NETFILTER
716062fd HX	53	__skb_push(skb, skb->data - skb_network_header(skb));
	54	ip_hdr(skb)->tot_len = htons(skb->len);
	55	ip_send_check(ip_hdr(skb));
b05e1066	56
716062fd HX	57	NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
	58	xfrm4_rcv_encap_finish);
	59	return 0;
b05e1066	60	#else
716062fd	61	return -ip_hdr(skb)->protocol;
b05e1066	62	#endif
1da177e4	63	}
067b207b JC	64
	65	/* If it's a keepalive packet, then just eat it.
	66	* If it's an encapsulated packet, then pass it to the
	67	* IPsec xfrm input.
	68	* Returns 0 if skb passed to xfrm or was dropped.
	69	* Returns >0 if skb should be passed to UDP.
	70	* Returns <0 if skb should be resubmitted (-ret is protocol)
	71	*/
	72	int xfrm4_udp_encap_rcv(struct sock sk, struct sk_buff skb)
	73	{
	74	struct udp_sock *up = udp_sk(sk);
	75	struct udphdr *uh;
	76	struct iphdr *iph;
	77	int iphlen, len;
	78	int ret;
	79
	80	__u8 *udpdata;
	81	__be32 *udpdata32;
	82	__u16 encap_type = up->encap_type;
	83
	84	/* if this is not encapsulated socket, then just return now */
	85	if (!encap_type)
	86	return 1;
	87
	88	/* If this is a paged skb, make sure we pull up
	89	* whatever data we need to look at. */
	90	len = skb->len - sizeof(struct udphdr);
	91	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
	92	return 1;
	93
	94	/* Now we can get the pointers */
	95	uh = udp_hdr(skb);
	96	udpdata = (__u8 *)uh + sizeof(struct udphdr);
	97	udpdata32 = (__be32 *)udpdata;
	98
	99	switch (encap_type) {
	100	default:
	101	case UDP_ENCAP_ESPINUDP:
	102	/* Check if this is a keepalive packet. If so, eat it. */
	103	if (len == 1 && udpdata[0] == 0xff) {
	104	goto drop;
	105	} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
	106	/* ESP Packet without Non-ESP header */
	107	len = sizeof(struct udphdr);
	108	} else
	109	/* Must be an IKE packet.. pass it through */
	110	return 1;
	111	break;
	112	case UDP_ENCAP_ESPINUDP_NON_IKE:
	113	/* Check if this is a keepalive packet. If so, eat it. */
	114	if (len == 1 && udpdata[0] == 0xff) {
	115	goto drop;
	116	} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
	117	udpdata32[0] == 0 && udpdata32[1] == 0) {
	118
	119	/* ESP Packet with Non-IKE marker */
	120	len = sizeof(struct udphdr) + 2 * sizeof(u32);
	121	} else
	122	/* Must be an IKE packet.. pass it through */
	123	return 1;
	124	break;
	125	}
	126
	127	/* At this point we are sure that this is an ESPinUDP packet,
128	* so we need to remove 'len' bytes from the packet (the UDP
129	* header and optional ESP marker bytes) and then modify the
130	* protocol to ESP, and then call into the transform receiver.
131	*/
132	if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
133	goto drop;
134
135	/* Now we can update and verify the packet length... */
136	iph = ip_hdr(skb);
137	iphlen = iph->ihl << 2;
138	iph->tot_len = htons(ntohs(iph->tot_len) - len);
139	if (skb->len < iphlen + len) {
140	/* packet is too small!?! */
141	goto drop;
142	}
143
144	/* pull the data buffer up to the ESP header and set the
145	* transport header to point to ESP. Keep UDP on the stack
146	* for later.
147	*/
148	__skb_pull(skb, len);
149	skb_reset_transport_header(skb);
150
067b207b	151	/* process ESP */
c4541b41	152	ret = xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
067b207b JC	153	return ret;
	154
	155	drop:
	156	kfree_skb(skb);
	157	return 0;
	158	}
	159
	160	int xfrm4_rcv(struct sk_buff *skb)
	161	{
c4541b41	162	return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
067b207b JC	163	}
	164
	165	EXPORT_SYMBOL(xfrm4_rcv);