[mirror_ubuntu-bionic-kernel.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 int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk,
				   struct sk_buff *skb)
{
	return dst_input(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;
	}

	if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2))
		goto drop;

	return 0;
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
acf568ee HX	26	static int xfrm4_rcv_encap_finish2(struct net net, struct sock sk,
	27	struct sk_buff *skb)
	28	{
	29	return dst_input(skb);
	30	}
	31
0c4b51f0 EB	32	static inline int xfrm4_rcv_encap_finish(struct net net, struct sock sk,
0c4b51f0 EB	33	struct sk_buff *skb)
b05e1066	34	{
51456b29	35	if (!skb_dst(skb)) {
eddc9ec5 ACM	36	const struct iphdr *iph = ip_hdr(skb);
eddc9ec5 ACM	37
c6cffba4 DM	38	if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
c6cffba4 DM	39	iph->tos, skb->dev))
b05e1066 PM	40	goto drop;
b05e1066 PM	41	}
acf568ee HX	42
	43	if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2))
	44	goto drop;
	45
	46	return 0;
b05e1066 PM	47	drop:
	48	kfree_skb(skb);
	49	return NET_RX_DROP;
	50	}
b05e1066	51
716062fd HX	52	int xfrm4_transport_finish(struct sk_buff *skb, int async)
716062fd HX	53	{
7785bba2	54	struct xfrm_offload *xo = xfrm_offload(skb);
60d5fcfb HX	55	struct iphdr *iph = ip_hdr(skb);
	56
	57	iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
	58
0883ae0e HX	59	#ifndef CONFIG_NETFILTER
	60	if (!async)
	61	return -iph->protocol;
	62	#endif
	63
716062fd	64	__skb_push(skb, skb->data - skb_network_header(skb));
60d5fcfb HX	65	iph->tot_len = htons(skb->len);
60d5fcfb HX	66	ip_send_check(iph);
b05e1066	67
7785bba2 SK	68	if (xo && (xo->flags & XFRM_GRO)) {
	69	skb_mac_header_rebuild(skb);
	70	return 0;
	71	}
	72
29a26a56 EB	73	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
29a26a56 EB	74	dev_net(skb->dev), NULL, skb, skb->dev, NULL,
716062fd HX	75	xfrm4_rcv_encap_finish);
716062fd HX	76	return 0;
1da177e4	77	}
067b207b JC	78
	79	/* If it's a keepalive packet, then just eat it.
	80	* If it's an encapsulated packet, then pass it to the
	81	* IPsec xfrm input.
	82	* Returns 0 if skb passed to xfrm or was dropped.
	83	* Returns >0 if skb should be passed to UDP.
	84	* Returns <0 if skb should be resubmitted (-ret is protocol)
	85	*/
	86	int xfrm4_udp_encap_rcv(struct sock sk, struct sk_buff skb)
	87	{
	88	struct udp_sock *up = udp_sk(sk);
	89	struct udphdr *uh;
	90	struct iphdr *iph;
	91	int iphlen, len;
067b207b JC	92
	93	__u8 *udpdata;
	94	__be32 *udpdata32;
	95	__u16 encap_type = up->encap_type;
	96
	97	/* if this is not encapsulated socket, then just return now */
	98	if (!encap_type)
	99	return 1;
	100
	101	/* If this is a paged skb, make sure we pull up
	102	* whatever data we need to look at. */
	103	len = skb->len - sizeof(struct udphdr);
	104	if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
	105	return 1;
	106
	107	/* Now we can get the pointers */
	108	uh = udp_hdr(skb);
	109	udpdata = (__u8 *)uh + sizeof(struct udphdr);
	110	udpdata32 = (__be32 *)udpdata;
	111
	112	switch (encap_type) {
	113	default:
	114	case UDP_ENCAP_ESPINUDP:
	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 > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
	119	/* ESP Packet without Non-ESP header */
	120	len = sizeof(struct udphdr);
	121	} else
	122	/* Must be an IKE packet.. pass it through */
	123	return 1;
	124	break;
	125	case UDP_ENCAP_ESPINUDP_NON_IKE:
	126	/* Check if this is a keepalive packet. If so, eat it. */
	127	if (len == 1 && udpdata[0] == 0xff) {
	128	goto drop;
	129	} else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
	130	udpdata32[0] == 0 && udpdata32[1] == 0) {
	131
	132	/* ESP Packet with Non-IKE marker */
	133	len = sizeof(struct udphdr) + 2 * sizeof(u32);
	134	} else
	135	/* Must be an IKE packet.. pass it through */
	136	return 1;
	137	break;
	138	}
	139
	140	/* At this point we are sure that this is an ESPinUDP packet,
	141	* so we need to remove 'len' bytes from the packet (the UDP
	142	* header and optional ESP marker bytes) and then modify the
	143	* protocol to ESP, and then call into the transform receiver.
	144	*/
14bbd6a5	145	if (skb_unclone(skb, GFP_ATOMIC))
067b207b JC	146	goto drop;
	147
	148	/* Now we can update and verify the packet length... */
	149	iph = ip_hdr(skb);
	150	iphlen = iph->ihl << 2;
	151	iph->tot_len = htons(ntohs(iph->tot_len) - len);
	152	if (skb->len < iphlen + len) {
	153	/* packet is too small!?! */
	154	goto drop;
	155	}
	156
	157	/* pull the data buffer up to the ESP header and set the
	158	* transport header to point to ESP. Keep UDP on the stack
	159	* for later.
	160	*/
	161	__skb_pull(skb, len);
	162	skb_reset_transport_header(skb);
	163
067b207b	164	/* process ESP */
f2712fd0	165	return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
067b207b JC	166
	167	drop:
	168	kfree_skb(skb);
	169	return 0;
	170	}
	171
	172	int xfrm4_rcv(struct sk_buff *skb)
	173	{
c4541b41	174	return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
067b207b	175	}
067b207b	176	EXPORT_SYMBOL(xfrm4_rcv);