/* * xfrm4_mode_tunnel.c - Tunnel mode encapsulation for IPv4. * * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au> */ #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/skbuff.h> #include <linux/stringify.h> #include <net/dst.h> #include <net/inet_ecn.h> #include <net/ip.h> #include <net/xfrm.h> static inline void ipip_ecn_decapsulate(struct sk_buff *skb) { struct iphdr *outer_iph = skb->nh.iph; struct iphdr *inner_iph = skb->h.ipiph; if (INET_ECN_is_ce(outer_iph->tos)) IP_ECN_set_ce(inner_iph); } /* Add encapsulation header. * * The top IP header will be constructed per RFC 2401. The following fields * in it shall be filled in by x->type->output: * tot_len * check * * On exit, skb->h will be set to the start of the payload to be processed * by x->type->output and skb->nh will be set to the top IP header. */ static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb) { struct dst_entry *dst = skb->dst; struct iphdr *iph, *top_iph; int flags; iph = skb->nh.iph; skb->h.ipiph = iph; skb->nh.raw = skb_push(skb, x->props.header_len); top_iph = skb->nh.iph; top_iph->ihl = 5; top_iph->version = 4; /* DS disclosed */ top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos); flags = x->props.flags; if (flags & XFRM_STATE_NOECN) IP_ECN_clear(top_iph); top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ? 0 : (iph->frag_off & htons(IP_DF)); if (!top_iph->frag_off) __ip_select_ident(top_iph, dst->child, 0); top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT); top_iph->saddr = x->props.saddr.a4; top_iph->daddr = x->id.daddr.a4; top_iph->protocol = IPPROTO_IPIP; memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options)); return 0; } static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb) { struct iphdr *iph = skb->nh.iph; int err = -EINVAL; if (iph->protocol != IPPROTO_IPIP) goto out; if (!pskb_may_pull(skb, sizeof(struct iphdr))) goto out; if (skb_cloned(skb) && (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) goto out; if (x->props.flags & XFRM_STATE_DECAP_DSCP) ipv4_copy_dscp(iph, skb->h.ipiph); if (!(x->props.flags & XFRM_STATE_NOECN)) ipip_ecn_decapsulate(skb); skb->mac.raw = memmove(skb->data - skb->mac_len, skb->mac.raw, skb->mac_len); skb->nh.raw = skb->data; err = 0; out: return err; } static struct xfrm_mode xfrm4_tunnel_mode = { .input = xfrm4_tunnel_input, .output = xfrm4_tunnel_output, .owner = THIS_MODULE, .encap = XFRM_MODE_TUNNEL, }; static int __init xfrm4_tunnel_init(void) { return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET); } static void __exit xfrm4_tunnel_exit(void) { int err; err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET); BUG_ON(err); } module_init(xfrm4_tunnel_init); module_exit(xfrm4_tunnel_exit); MODULE_LICENSE("GPL"); MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);