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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 | */ |
12 | ||
5a0e3ad6 | 13 | #include <linux/slab.h> |
1da177e4 LT |
14 | #include <linux/module.h> |
15 | #include <linux/string.h> | |
b05e1066 PM |
16 | #include <linux/netfilter.h> |
17 | #include <linux/netfilter_ipv4.h> | |
1da177e4 LT |
18 | #include <net/ip.h> |
19 | #include <net/xfrm.h> | |
20 | ||
acf568ee HX |
21 | static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk, |
22 | struct sk_buff *skb) | |
23 | { | |
24 | return dst_input(skb); | |
25 | } | |
26 | ||
0c4b51f0 EB |
27 | static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk, |
28 | struct sk_buff *skb) | |
b05e1066 | 29 | { |
51456b29 | 30 | if (!skb_dst(skb)) { |
eddc9ec5 ACM |
31 | const struct iphdr *iph = ip_hdr(skb); |
32 | ||
c6cffba4 DM |
33 | if (ip_route_input_noref(skb, iph->daddr, iph->saddr, |
34 | iph->tos, skb->dev)) | |
b05e1066 PM |
35 | goto drop; |
36 | } | |
acf568ee HX |
37 | |
38 | if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2)) | |
39 | goto drop; | |
40 | ||
41 | return 0; | |
b05e1066 PM |
42 | drop: |
43 | kfree_skb(skb); | |
44 | return NET_RX_DROP; | |
45 | } | |
b05e1066 | 46 | |
716062fd HX |
47 | int xfrm4_transport_finish(struct sk_buff *skb, int async) |
48 | { | |
7785bba2 | 49 | struct xfrm_offload *xo = xfrm_offload(skb); |
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); |
61 | ip_send_check(iph); | |
b05e1066 | 62 | |
7785bba2 SK |
63 | if (xo && (xo->flags & XFRM_GRO)) { |
64 | skb_mac_header_rebuild(skb); | |
bfc0698b | 65 | skb_reset_transport_header(skb); |
7785bba2 SK |
66 | return 0; |
67 | } | |
68 | ||
29a26a56 EB |
69 | NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, |
70 | dev_net(skb->dev), NULL, skb, skb->dev, NULL, | |
716062fd HX |
71 | xfrm4_rcv_encap_finish); |
72 | return 0; | |
1da177e4 | 73 | } |
067b207b JC |
74 | |
75 | /* If it's a keepalive packet, then just eat it. | |
76 | * If it's an encapsulated packet, then pass it to the | |
77 | * IPsec xfrm input. | |
78 | * Returns 0 if skb passed to xfrm or was dropped. | |
79 | * Returns >0 if skb should be passed to UDP. | |
80 | * Returns <0 if skb should be resubmitted (-ret is protocol) | |
81 | */ | |
82 | int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) | |
83 | { | |
84 | struct udp_sock *up = udp_sk(sk); | |
85 | struct udphdr *uh; | |
86 | struct iphdr *iph; | |
87 | int iphlen, len; | |
067b207b JC |
88 | |
89 | __u8 *udpdata; | |
90 | __be32 *udpdata32; | |
91 | __u16 encap_type = up->encap_type; | |
92 | ||
93 | /* if this is not encapsulated socket, then just return now */ | |
94 | if (!encap_type) | |
95 | return 1; | |
96 | ||
97 | /* If this is a paged skb, make sure we pull up | |
98 | * whatever data we need to look at. */ | |
99 | len = skb->len - sizeof(struct udphdr); | |
100 | if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8))) | |
101 | return 1; | |
102 | ||
103 | /* Now we can get the pointers */ | |
104 | uh = udp_hdr(skb); | |
105 | udpdata = (__u8 *)uh + sizeof(struct udphdr); | |
106 | udpdata32 = (__be32 *)udpdata; | |
107 | ||
108 | switch (encap_type) { | |
109 | default: | |
110 | case UDP_ENCAP_ESPINUDP: | |
111 | /* Check if this is a keepalive packet. If so, eat it. */ | |
112 | if (len == 1 && udpdata[0] == 0xff) { | |
113 | goto drop; | |
114 | } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) { | |
115 | /* ESP Packet without Non-ESP header */ | |
116 | len = sizeof(struct udphdr); | |
117 | } else | |
118 | /* Must be an IKE packet.. pass it through */ | |
119 | return 1; | |
120 | break; | |
121 | case UDP_ENCAP_ESPINUDP_NON_IKE: | |
122 | /* Check if this is a keepalive packet. If so, eat it. */ | |
123 | if (len == 1 && udpdata[0] == 0xff) { | |
124 | goto drop; | |
125 | } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) && | |
126 | udpdata32[0] == 0 && udpdata32[1] == 0) { | |
127 | ||
128 | /* ESP Packet with Non-IKE marker */ | |
129 | len = sizeof(struct udphdr) + 2 * sizeof(u32); | |
130 | } else | |
131 | /* Must be an IKE packet.. pass it through */ | |
132 | return 1; | |
133 | break; | |
134 | } | |
135 | ||
136 | /* At this point we are sure that this is an ESPinUDP packet, | |
137 | * so we need to remove 'len' bytes from the packet (the UDP | |
138 | * header and optional ESP marker bytes) and then modify the | |
139 | * protocol to ESP, and then call into the transform receiver. | |
140 | */ | |
14bbd6a5 | 141 | if (skb_unclone(skb, GFP_ATOMIC)) |
067b207b JC |
142 | goto drop; |
143 | ||
144 | /* Now we can update and verify the packet length... */ | |
145 | iph = ip_hdr(skb); | |
146 | iphlen = iph->ihl << 2; | |
147 | iph->tot_len = htons(ntohs(iph->tot_len) - len); | |
148 | if (skb->len < iphlen + len) { | |
149 | /* packet is too small!?! */ | |
150 | goto drop; | |
151 | } | |
152 | ||
153 | /* pull the data buffer up to the ESP header and set the | |
154 | * transport header to point to ESP. Keep UDP on the stack | |
155 | * for later. | |
156 | */ | |
157 | __skb_pull(skb, len); | |
158 | skb_reset_transport_header(skb); | |
159 | ||
067b207b | 160 | /* process ESP */ |
f2712fd0 | 161 | return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type); |
067b207b JC |
162 | |
163 | drop: | |
164 | kfree_skb(skb); | |
165 | return 0; | |
166 | } | |
167 | ||
168 | int xfrm4_rcv(struct sk_buff *skb) | |
169 | { | |
c4541b41 | 170 | return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); |
067b207b | 171 | } |
067b207b | 172 | EXPORT_SYMBOL(xfrm4_rcv); |