2 * xfrm4_mode_tunnel.c - Tunnel mode encapsulation for IPv4.
4 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
7 #include <linux/init.h>
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <linux/stringify.h>
13 #include <net/inet_ecn.h>
17 static inline void ipip_ecn_decapsulate(struct sk_buff
*skb
)
19 struct iphdr
*inner_iph
= ipip_hdr(skb
);
21 if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb
)->tos
))
22 IP_ECN_set_ce(inner_iph
);
25 /* Add encapsulation header.
27 * The top IP header will be constructed per RFC 2401.
29 static int xfrm4_mode_tunnel_output(struct xfrm_state
*x
, struct sk_buff
*skb
)
31 struct dst_entry
*dst
= skb
->dst
;
32 struct iphdr
*top_iph
;
35 skb_set_network_header(skb
, -x
->props
.header_len
);
36 skb
->mac_header
= skb
->network_header
+
37 offsetof(struct iphdr
, protocol
);
38 skb
->transport_header
= skb
->network_header
+ sizeof(*top_iph
);
39 top_iph
= ip_hdr(skb
);
44 top_iph
->protocol
= xfrm_af2proto(skb
->dst
->ops
->family
);
47 top_iph
->tos
= INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb
)->tos
,
48 XFRM_MODE_SKB_CB(skb
)->tos
);
50 flags
= x
->props
.flags
;
51 if (flags
& XFRM_STATE_NOECN
)
52 IP_ECN_clear(top_iph
);
54 top_iph
->frag_off
= (flags
& XFRM_STATE_NOPMTUDISC
) ?
55 0 : (XFRM_MODE_SKB_CB(skb
)->frag_off
& htons(IP_DF
));
56 ip_select_ident(top_iph
, dst
->child
, NULL
);
58 top_iph
->ttl
= dst_metric(dst
->child
, RTAX_HOPLIMIT
);
60 top_iph
->saddr
= x
->props
.saddr
.a4
;
61 top_iph
->daddr
= x
->id
.daddr
.a4
;
66 static int xfrm4_mode_tunnel_input(struct xfrm_state
*x
, struct sk_buff
*skb
)
68 const unsigned char *old_mac
;
71 if (XFRM_MODE_SKB_CB(skb
)->protocol
!= IPPROTO_IPIP
)
74 if (!pskb_may_pull(skb
, sizeof(struct iphdr
)))
77 if (skb_cloned(skb
) &&
78 (err
= pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
)))
81 if (x
->props
.flags
& XFRM_STATE_DECAP_DSCP
)
82 ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb
)->tos
, ipip_hdr(skb
));
83 if (!(x
->props
.flags
& XFRM_STATE_NOECN
))
84 ipip_ecn_decapsulate(skb
);
86 old_mac
= skb_mac_header(skb
);
87 skb_set_mac_header(skb
, -skb
->mac_len
);
88 memmove(skb_mac_header(skb
), old_mac
, skb
->mac_len
);
89 skb_reset_network_header(skb
);
96 static struct xfrm_mode xfrm4_tunnel_mode
= {
97 .input2
= xfrm4_mode_tunnel_input
,
98 .input
= xfrm_prepare_input
,
99 .output2
= xfrm4_mode_tunnel_output
,
100 .output
= xfrm4_prepare_output
,
101 .owner
= THIS_MODULE
,
102 .encap
= XFRM_MODE_TUNNEL
,
103 .flags
= XFRM_MODE_FLAG_TUNNEL
,
106 static int __init
xfrm4_mode_tunnel_init(void)
108 return xfrm_register_mode(&xfrm4_tunnel_mode
, AF_INET
);
111 static void __exit
xfrm4_mode_tunnel_exit(void)
115 err
= xfrm_unregister_mode(&xfrm4_tunnel_mode
, AF_INET
);
119 module_init(xfrm4_mode_tunnel_init
);
120 module_exit(xfrm4_mode_tunnel_exit
);
121 MODULE_LICENSE("GPL");
122 MODULE_ALIAS_XFRM_MODE(AF_INET
, XFRM_MODE_TUNNEL
);