[mirror_ubuntu-bionic-kernel.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);
}

static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
{
	if (skb_dst(skb) == 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;
}

int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
		    int encap_type)
{
	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
	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)
{
	struct iphdr *iph = ip_hdr(skb);

	iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;

#ifndef CONFIG_NETFILTER
	if (!async)
		return -iph->protocol;
#endif

	__skb_push(skb, skb->data - skb_network_header(skb));
	iph->tot_len = htons(skb->len);
	ip_send_check(iph);

	NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
		xfrm4_rcv_encap_finish);
	return 0;
}

/* 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;

	__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 */
	return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);

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	static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
b05e1066 PM	25	{
adf30907	26	if (skb_dst(skb) == NULL) {
eddc9ec5 ACM	27	const struct iphdr *iph = ip_hdr(skb);
eddc9ec5 ACM	28
b05e1066	29	if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
e905a9ed	30	skb->dev))
b05e1066 PM	31	goto drop;
	32	}
	33	return dst_input(skb);
	34	drop:
	35	kfree_skb(skb);
	36	return NET_RX_DROP;
	37	}
b05e1066	38
c4541b41 HX	39	int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
c4541b41 HX	40	int encap_type)
1da177e4	41	{
2fcb45b6	42	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
716062fd HX	43	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
	44	return xfrm_input(skb, nexthdr, spi, encap_type);
	45	}
	46	EXPORT_SYMBOL(xfrm4_rcv_encap);
b05e1066	47
716062fd HX	48	int xfrm4_transport_finish(struct sk_buff *skb, int async)
716062fd HX	49	{
60d5fcfb HX	50	struct iphdr *iph = ip_hdr(skb);
	51
	52	iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
	53
0883ae0e HX	54	#ifndef CONFIG_NETFILTER
	55	if (!async)
	56	return -iph->protocol;
	57	#endif
	58
716062fd	59	__skb_push(skb, skb->data - skb_network_header(skb));
60d5fcfb HX	60	iph->tot_len = htons(skb->len);
60d5fcfb HX	61	ip_send_check(iph);
b05e1066	62
6e23ae2a	63	NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
716062fd HX	64	xfrm4_rcv_encap_finish);
716062fd HX	65	return 0;
1da177e4	66	}
067b207b JC	67
	68	/* If it's a keepalive packet, then just eat it.
	69	* If it's an encapsulated packet, then pass it to the
	70	* IPsec xfrm input.
	71	* Returns 0 if skb passed to xfrm or was dropped.
	72	* Returns >0 if skb should be passed to UDP.
	73	* Returns <0 if skb should be resubmitted (-ret is protocol)
	74	*/
	75	int xfrm4_udp_encap_rcv(struct sock sk, struct sk_buff skb)
	76	{
	77	struct udp_sock *up = udp_sk(sk);
	78	struct udphdr *uh;
	79	struct iphdr *iph;
	80	int iphlen, len;
067b207b JC	81
	82	__u8 *udpdata;
	83	__be32 *udpdata32;
	84	__u16 encap_type = up->encap_type;
	85
	86	/* if this is not encapsulated socket, then just return now */
	87	if (!encap_type)
	88	return 1;
	89
	90	/* If this is a paged skb, make sure we pull up
	91	* whatever data we need to look at. */
	92	len = skb->len - sizeof(struct udphdr);
	93	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
	94	return 1;
	95
	96	/* Now we can get the pointers */
	97	uh = udp_hdr(skb);
	98	udpdata = (__u8 *)uh + sizeof(struct udphdr);
	99	udpdata32 = (__be32 *)udpdata;
	100
	101	switch (encap_type) {
	102	default:
	103	case UDP_ENCAP_ESPINUDP:
	104	/* Check if this is a keepalive packet. If so, eat it. */
	105	if (len == 1 && udpdata[0] == 0xff) {
	106	goto drop;
	107	} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
	108	/* ESP Packet without Non-ESP header */
	109	len = sizeof(struct udphdr);
	110	} else
	111	/* Must be an IKE packet.. pass it through */
	112	return 1;
	113	break;
	114	case UDP_ENCAP_ESPINUDP_NON_IKE:
	115	/* Check if this is a keepalive packet. If so, eat it. */
	116	if (len == 1 && udpdata[0] == 0xff) {
	117	goto drop;
	118	} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
	119	udpdata32[0] == 0 && udpdata32[1] == 0) {
	120
	121	/* ESP Packet with Non-IKE marker */
	122	len = sizeof(struct udphdr) + 2 * sizeof(u32);
	123	} else
	124	/* Must be an IKE packet.. pass it through */
	125	return 1;
	126	break;
	127	}
	128
	129	/* At this point we are sure that this is an ESPinUDP packet,
	130	* so we need to remove 'len' bytes from the packet (the UDP
	131	* header and optional ESP marker bytes) and then modify the
	132	* protocol to ESP, and then call into the transform receiver.
	133	*/
	134	if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
	135	goto drop;
	136
	137	/* Now we can update and verify the packet length... */
	138	iph = ip_hdr(skb);
	139	iphlen = iph->ihl << 2;
	140	iph->tot_len = htons(ntohs(iph->tot_len) - len);
	141	if (skb->len < iphlen + len) {
	142	/* packet is too small!?! */
	143	goto drop;
	144	}
145
146	/* pull the data buffer up to the ESP header and set the
147	* transport header to point to ESP. Keep UDP on the stack
148	* for later.
149	*/
150	__skb_pull(skb, len);
151	skb_reset_transport_header(skb);
152
067b207b	153	/* process ESP */
f2712fd0	154	return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
067b207b JC	155
	156	drop:
	157	kfree_skb(skb);
	158	return 0;
	159	}
	160
	161	int xfrm4_rcv(struct sk_buff *skb)
	162	{
c4541b41	163	return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
067b207b JC	164	}
	165
	166	EXPORT_SYMBOL(xfrm4_rcv);