[linux-2.6-block.git] / net / ipv4 / xfrm4_input.c

// SPDX-License-Identifier: GPL-2.0
/*
 * xfrm4_input.c
 *
 * Changes:
 *	YOSHIFUJI Hideaki @USAGI
 *		Split up af-specific portion
 *	Derek Atkins <derek@ihtfp.com>
 *		Add Encapsulation support
 *
 */

#include <linux/slab.h>
#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 net *net, struct sock *sk,
					 struct sk_buff *skb)
{
	if (!skb_dst(skb)) {
		const struct iphdr *iph = ip_hdr(skb);

		if (ip_route_input_noref(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_transport_finish(struct sk_buff *skb, int async)
{
	struct xfrm_offload *xo = xfrm_offload(skb);
	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);

	if (xo && (xo->flags & XFRM_GRO)) {
		skb_mac_header_rebuild(skb);
		return 0;
	}

	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
		dev_net(skb->dev), NULL, 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_unclone(skb, 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
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* xfrm4_input.c
	4	*
	5	* Changes:
	6	* YOSHIFUJI Hideaki @USAGI
	7	* Split up af-specific portion
	8	* Derek Atkins <derek@ihtfp.com>
	9	* Add Encapsulation support
e905a9ed	10	*
1da177e4 LT	11	*/
1da177e4 LT	12
5a0e3ad6	13	#include <linux/slab.h>
1da177e4 LT	14	#include <linux/module.h>
1da177e4 LT	15	#include <linux/string.h>
b05e1066 PM	16	#include <linux/netfilter.h>
b05e1066 PM	17	#include <linux/netfilter_ipv4.h>
1da177e4 LT	18	#include <net/ip.h>
	19	#include <net/xfrm.h>
	20
227620e2 HX	21	int xfrm4_extract_input(struct xfrm_state x, struct sk_buff skb)
	22	{
	23	return xfrm4_extract_header(skb);
	24	}
	25
0c4b51f0 EB	26	static inline int xfrm4_rcv_encap_finish(struct net net, struct sock sk,
0c4b51f0 EB	27	struct sk_buff *skb)
b05e1066	28	{
51456b29	29	if (!skb_dst(skb)) {
eddc9ec5 ACM	30	const struct iphdr *iph = ip_hdr(skb);
eddc9ec5 ACM	31
c6cffba4 DM	32	if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
c6cffba4 DM	33	iph->tos, skb->dev))
b05e1066 PM	34	goto drop;
	35	}
	36	return dst_input(skb);
	37	drop:
	38	kfree_skb(skb);
	39	return NET_RX_DROP;
	40	}
b05e1066	41
716062fd HX	42	int xfrm4_transport_finish(struct sk_buff *skb, int async)
716062fd HX	43	{
7785bba2	44	struct xfrm_offload *xo = xfrm_offload(skb);
60d5fcfb HX	45	struct iphdr *iph = ip_hdr(skb);
	46
	47	iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
	48
0883ae0e HX	49	#ifndef CONFIG_NETFILTER
	50	if (!async)
	51	return -iph->protocol;
	52	#endif
	53
716062fd	54	__skb_push(skb, skb->data - skb_network_header(skb));
60d5fcfb HX	55	iph->tot_len = htons(skb->len);
60d5fcfb HX	56	ip_send_check(iph);
b05e1066	57
7785bba2 SK	58	if (xo && (xo->flags & XFRM_GRO)) {
	59	skb_mac_header_rebuild(skb);
	60	return 0;
	61	}
	62
29a26a56 EB	63	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
29a26a56 EB	64	dev_net(skb->dev), NULL, skb, skb->dev, NULL,
716062fd HX	65	xfrm4_rcv_encap_finish);
716062fd HX	66	return 0;
1da177e4	67	}
067b207b JC	68
	69	/* If it's a keepalive packet, then just eat it.
	70	* If it's an encapsulated packet, then pass it to the
	71	* IPsec xfrm input.
	72	* Returns 0 if skb passed to xfrm or was dropped.
	73	* Returns >0 if skb should be passed to UDP.
	74	* Returns <0 if skb should be resubmitted (-ret is protocol)
	75	*/
	76	int xfrm4_udp_encap_rcv(struct sock sk, struct sk_buff skb)
	77	{
	78	struct udp_sock *up = udp_sk(sk);
	79	struct udphdr *uh;
	80	struct iphdr *iph;
	81	int iphlen, len;
067b207b JC	82
	83	__u8 *udpdata;
	84	__be32 *udpdata32;
	85	__u16 encap_type = up->encap_type;
	86
	87	/* if this is not encapsulated socket, then just return now */
	88	if (!encap_type)
	89	return 1;
	90
	91	/* If this is a paged skb, make sure we pull up
	92	* whatever data we need to look at. */
	93	len = skb->len - sizeof(struct udphdr);
	94	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
	95	return 1;
	96
	97	/* Now we can get the pointers */
	98	uh = udp_hdr(skb);
	99	udpdata = (__u8 *)uh + sizeof(struct udphdr);
	100	udpdata32 = (__be32 *)udpdata;
	101
	102	switch (encap_type) {
	103	default:
	104	case UDP_ENCAP_ESPINUDP:
	105	/* Check if this is a keepalive packet. If so, eat it. */
	106	if (len == 1 && udpdata[0] == 0xff) {
	107	goto drop;
	108	} else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
	109	/* ESP Packet without Non-ESP header */
	110	len = sizeof(struct udphdr);
	111	} else
	112	/* Must be an IKE packet.. pass it through */
	113	return 1;
	114	break;
	115	case UDP_ENCAP_ESPINUDP_NON_IKE:
	116	/* Check if this is a keepalive packet. If so, eat it. */
	117	if (len == 1 && udpdata[0] == 0xff) {
	118	goto drop;
	119	} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
	120	udpdata32[0] == 0 && udpdata32[1] == 0) {
	121
	122	/* ESP Packet with Non-IKE marker */
	123	len = sizeof(struct udphdr) + 2 * sizeof(u32);
	124	} else
	125	/* Must be an IKE packet.. pass it through */
	126	return 1;
	127	break;
	128	}
	129
	130	/* At this point we are sure that this is an ESPinUDP packet,
	131	* so we need to remove 'len' bytes from the packet (the UDP
	132	* header and optional ESP marker bytes) and then modify the
	133	* protocol to ESP, and then call into the transform receiver.
	134	*/
14bbd6a5	135	if (skb_unclone(skb, GFP_ATOMIC))
067b207b JC	136	goto drop;
	137
	138	/* Now we can update and verify the packet length... */
	139	iph = ip_hdr(skb);
	140	iphlen = iph->ihl << 2;
	141	iph->tot_len = htons(ntohs(iph->tot_len) - len);
	142	if (skb->len < iphlen + len) {
	143	/* packet is too small!?! */
	144	goto drop;
	145	}
	146
	147	/* pull the data buffer up to the ESP header and set the
	148	* transport header to point to ESP. Keep UDP on the stack
	149	* for later.
	150	*/
	151	__skb_pull(skb, len);
	152	skb_reset_transport_header(skb);
	153
067b207b	154	/* process ESP */
f2712fd0	155	return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
067b207b JC	156
	157	drop:
	158	kfree_skb(skb);
	159	return 0;
	160	}
	161
	162	int xfrm4_rcv(struct sk_buff *skb)
	163	{
c4541b41	164	return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
067b207b	165	}
067b207b	166	EXPORT_SYMBOL(xfrm4_rcv);