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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 |
9 | * |
10 | */ |
11 | |
12 | #include <linux/slab.h> |
13 | #include <linux/module.h> |
14 | #include <linux/string.h> |
15 | #include <linux/netfilter.h> |
16 | #include <linux/netfilter_ipv4.h> |
17 | #include <net/ip.h> |
18 | #include <net/xfrm.h> |
19 | |
20 | int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb) |
21 | { |
22 | return xfrm4_extract_header(skb); |
23 | } |
24 | |
25 | static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb) |
26 | { |
27 | if (skb_dst(skb) == NULL) { |
28 | const struct iphdr *iph = ip_hdr(skb); |
29 | |
30 | if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, |
31 | skb->dev)) |
32 | goto drop; |
33 | } |
34 | return dst_input(skb); |
35 | drop: |
36 | kfree_skb(skb); |
37 | return NET_RX_DROP; |
38 | } |
39 | |
40 | int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi, |
41 | int encap_type) |
42 | { |
43 | XFRM_SPI_SKB_CB(skb)->family = AF_INET; |
44 | XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr); |
45 | return xfrm_input(skb, nexthdr, spi, encap_type); |
46 | } |
47 | EXPORT_SYMBOL(xfrm4_rcv_encap); |
48 | |
49 | int xfrm4_transport_finish(struct sk_buff *skb, int async) |
50 | { |
51 | struct iphdr *iph = ip_hdr(skb); |
52 | |
53 | iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; |
54 | |
55 | #ifndef CONFIG_NETFILTER |
56 | if (!async) |
57 | return -iph->protocol; |
58 | #endif |
59 | |
60 | __skb_push(skb, skb->data - skb_network_header(skb)); |
61 | iph->tot_len = htons(skb->len); |
62 | ip_send_check(iph); |
63 | |
64 | NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, |
65 | xfrm4_rcv_encap_finish); |
66 | return 0; |
67 | } |
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; |
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 | */ |
135 | if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
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 | |
154 | /* process ESP */ |
155 | return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type); |
156 | |
157 | drop: |
158 | kfree_skb(skb); |
159 | return 0; |
160 | } |
161 | |
162 | int xfrm4_rcv(struct sk_buff *skb) |
163 | { |
164 | return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); |
165 | } |
166 | |
167 | EXPORT_SYMBOL(xfrm4_rcv); |
168 |
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Tags:
od-2011-09-04
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