1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0
21da177e4SLinus Torvalds /*
31da177e4SLinus Torvalds * xfrm4_input.c
41da177e4SLinus Torvalds *
51da177e4SLinus Torvalds * Changes:
61da177e4SLinus Torvalds * YOSHIFUJI Hideaki @USAGI
71da177e4SLinus Torvalds * Split up af-specific portion
81da177e4SLinus Torvalds * Derek Atkins <derek@ihtfp.com>
91da177e4SLinus Torvalds * Add Encapsulation support
101da177e4SLinus Torvalds *
111da177e4SLinus Torvalds */
121da177e4SLinus Torvalds
135a0e3ad6STejun Heo #include <linux/slab.h>
141da177e4SLinus Torvalds #include <linux/module.h>
151da177e4SLinus Torvalds #include <linux/string.h>
16b05e1066SPatrick McHardy #include <linux/netfilter.h>
17b05e1066SPatrick McHardy #include <linux/netfilter_ipv4.h>
181da177e4SLinus Torvalds #include <net/ip.h>
191da177e4SLinus Torvalds #include <net/xfrm.h>
201da177e4SLinus Torvalds
xfrm4_rcv_encap_finish2(struct net * net,struct sock * sk,struct sk_buff * skb)21acf568eeSHerbert Xu static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk,
22acf568eeSHerbert Xu struct sk_buff *skb)
23acf568eeSHerbert Xu {
24acf568eeSHerbert Xu return dst_input(skb);
25acf568eeSHerbert Xu }
26acf568eeSHerbert Xu
xfrm4_rcv_encap_finish(struct net * net,struct sock * sk,struct sk_buff * skb)270c4b51f0SEric W. Biederman static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk,
280c4b51f0SEric W. Biederman struct sk_buff *skb)
29b05e1066SPatrick McHardy {
3051456b29SIan Morris if (!skb_dst(skb)) {
31eddc9ec5SArnaldo Carvalho de Melo const struct iphdr *iph = ip_hdr(skb);
32eddc9ec5SArnaldo Carvalho de Melo
33c6cffba4SDavid S. Miller if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
34c10237e0SDavid S. Miller iph->tos, skb->dev))
35b05e1066SPatrick McHardy goto drop;
36b05e1066SPatrick McHardy }
37acf568eeSHerbert Xu
38acf568eeSHerbert Xu if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2))
39acf568eeSHerbert Xu goto drop;
40acf568eeSHerbert Xu
41acf568eeSHerbert Xu return 0;
42b05e1066SPatrick McHardy drop:
43b05e1066SPatrick McHardy kfree_skb(skb);
44b05e1066SPatrick McHardy return NET_RX_DROP;
45b05e1066SPatrick McHardy }
46b05e1066SPatrick McHardy
xfrm4_transport_finish(struct sk_buff * skb,int async)47716062fdSHerbert Xu int xfrm4_transport_finish(struct sk_buff *skb, int async)
48716062fdSHerbert Xu {
497785bba2SSteffen Klassert struct xfrm_offload *xo = xfrm_offload(skb);
5060d5fcfbSHerbert Xu struct iphdr *iph = ip_hdr(skb);
5160d5fcfbSHerbert Xu
5260d5fcfbSHerbert Xu iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
5360d5fcfbSHerbert Xu
540883ae0eSHerbert Xu #ifndef CONFIG_NETFILTER
550883ae0eSHerbert Xu if (!async)
560883ae0eSHerbert Xu return -iph->protocol;
570883ae0eSHerbert Xu #endif
580883ae0eSHerbert Xu
59d56f90a7SArnaldo Carvalho de Melo __skb_push(skb, skb->data - skb_network_header(skb));
6060d5fcfbSHerbert Xu iph->tot_len = htons(skb->len);
6160d5fcfbSHerbert Xu ip_send_check(iph);
62b05e1066SPatrick McHardy
637785bba2SSteffen Klassert if (xo && (xo->flags & XFRM_GRO)) {
644a9771c0SPaul Davey /* The full l2 header needs to be preserved so that re-injecting the packet at l2
654a9771c0SPaul Davey * works correctly in the presence of vlan tags.
664a9771c0SPaul Davey */
674a9771c0SPaul Davey skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
684a9771c0SPaul Davey skb_reset_network_header(skb);
69bfc0698bSSowmini Varadhan skb_reset_transport_header(skb);
707785bba2SSteffen Klassert return 0;
717785bba2SSteffen Klassert }
727785bba2SSteffen Klassert
7329a26a56SEric W. Biederman NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
7429a26a56SEric W. Biederman dev_net(skb->dev), NULL, skb, skb->dev, NULL,
75b05e1066SPatrick McHardy xfrm4_rcv_encap_finish);
76b05e1066SPatrick McHardy return 0;
771da177e4SLinus Torvalds }
781da177e4SLinus Torvalds
79067b207bSJames Chapman /* If it's a keepalive packet, then just eat it.
80067b207bSJames Chapman * If it's an encapsulated packet, then pass it to the
81067b207bSJames Chapman * IPsec xfrm input.
82067b207bSJames Chapman * Returns 0 if skb passed to xfrm or was dropped.
83067b207bSJames Chapman * Returns >0 if skb should be passed to UDP.
84067b207bSJames Chapman * Returns <0 if skb should be resubmitted (-ret is protocol)
85067b207bSJames Chapman */
xfrm4_udp_encap_rcv(struct sock * sk,struct sk_buff * skb)86067b207bSJames Chapman int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
87067b207bSJames Chapman {
88067b207bSJames Chapman struct udp_sock *up = udp_sk(sk);
89067b207bSJames Chapman struct udphdr *uh;
90067b207bSJames Chapman struct iphdr *iph;
91067b207bSJames Chapman int iphlen, len;
92067b207bSJames Chapman __u8 *udpdata;
93067b207bSJames Chapman __be32 *udpdata32;
944781a75dSEric Dumazet u16 encap_type;
95067b207bSJames Chapman
964781a75dSEric Dumazet encap_type = READ_ONCE(up->encap_type);
97067b207bSJames Chapman /* if this is not encapsulated socket, then just return now */
98067b207bSJames Chapman if (!encap_type)
99067b207bSJames Chapman return 1;
100067b207bSJames Chapman
101067b207bSJames Chapman /* If this is a paged skb, make sure we pull up
102067b207bSJames Chapman * whatever data we need to look at. */
103067b207bSJames Chapman len = skb->len - sizeof(struct udphdr);
104067b207bSJames Chapman if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
105067b207bSJames Chapman return 1;
106067b207bSJames Chapman
107067b207bSJames Chapman /* Now we can get the pointers */
108067b207bSJames Chapman uh = udp_hdr(skb);
109067b207bSJames Chapman udpdata = (__u8 *)uh + sizeof(struct udphdr);
110067b207bSJames Chapman udpdata32 = (__be32 *)udpdata;
111067b207bSJames Chapman
112067b207bSJames Chapman switch (encap_type) {
113067b207bSJames Chapman default:
114067b207bSJames Chapman case UDP_ENCAP_ESPINUDP:
115067b207bSJames Chapman /* Check if this is a keepalive packet. If so, eat it. */
116067b207bSJames Chapman if (len == 1 && udpdata[0] == 0xff) {
117067b207bSJames Chapman goto drop;
118067b207bSJames Chapman } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
119067b207bSJames Chapman /* ESP Packet without Non-ESP header */
120067b207bSJames Chapman len = sizeof(struct udphdr);
121067b207bSJames Chapman } else
122067b207bSJames Chapman /* Must be an IKE packet.. pass it through */
123067b207bSJames Chapman return 1;
124067b207bSJames Chapman break;
125067b207bSJames Chapman case UDP_ENCAP_ESPINUDP_NON_IKE:
126067b207bSJames Chapman /* Check if this is a keepalive packet. If so, eat it. */
127067b207bSJames Chapman if (len == 1 && udpdata[0] == 0xff) {
128067b207bSJames Chapman goto drop;
129067b207bSJames Chapman } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
130067b207bSJames Chapman udpdata32[0] == 0 && udpdata32[1] == 0) {
131067b207bSJames Chapman
132067b207bSJames Chapman /* ESP Packet with Non-IKE marker */
133067b207bSJames Chapman len = sizeof(struct udphdr) + 2 * sizeof(u32);
134067b207bSJames Chapman } else
135067b207bSJames Chapman /* Must be an IKE packet.. pass it through */
136067b207bSJames Chapman return 1;
137067b207bSJames Chapman break;
138067b207bSJames Chapman }
139067b207bSJames Chapman
140067b207bSJames Chapman /* At this point we are sure that this is an ESPinUDP packet,
141067b207bSJames Chapman * so we need to remove 'len' bytes from the packet (the UDP
142067b207bSJames Chapman * header and optional ESP marker bytes) and then modify the
143067b207bSJames Chapman * protocol to ESP, and then call into the transform receiver.
144067b207bSJames Chapman */
14514bbd6a5SPravin B Shelar if (skb_unclone(skb, GFP_ATOMIC))
146067b207bSJames Chapman goto drop;
147067b207bSJames Chapman
148067b207bSJames Chapman /* Now we can update and verify the packet length... */
149067b207bSJames Chapman iph = ip_hdr(skb);
150067b207bSJames Chapman iphlen = iph->ihl << 2;
151067b207bSJames Chapman iph->tot_len = htons(ntohs(iph->tot_len) - len);
152067b207bSJames Chapman if (skb->len < iphlen + len) {
153067b207bSJames Chapman /* packet is too small!?! */
154067b207bSJames Chapman goto drop;
155067b207bSJames Chapman }
156067b207bSJames Chapman
157067b207bSJames Chapman /* pull the data buffer up to the ESP header and set the
158067b207bSJames Chapman * transport header to point to ESP. Keep UDP on the stack
159067b207bSJames Chapman * for later.
160067b207bSJames Chapman */
161067b207bSJames Chapman __skb_pull(skb, len);
162067b207bSJames Chapman skb_reset_transport_header(skb);
163067b207bSJames Chapman
164067b207bSJames Chapman /* process ESP */
165f2712fd0SHerbert Xu return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
166067b207bSJames Chapman
167067b207bSJames Chapman drop:
168067b207bSJames Chapman kfree_skb(skb);
169067b207bSJames Chapman return 0;
170067b207bSJames Chapman }
1711166a530SMaciej Żenczykowski EXPORT_SYMBOL(xfrm4_udp_encap_rcv);
172067b207bSJames Chapman
xfrm4_rcv(struct sk_buff * skb)173067b207bSJames Chapman int xfrm4_rcv(struct sk_buff *skb)
174067b207bSJames Chapman {
175c4541b41SHerbert Xu return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
176067b207bSJames Chapman }
177067b207bSJames Chapman EXPORT_SYMBOL(xfrm4_rcv);
178