1 files changed, 141 insertions, 0 deletions

diff --git a/net/ipv4/xfrm4_output.c b/net/ipv4/xfrm4_output.c
new file mode 100644
index 000000000000..af2392ae5769
--- /dev/null
+++ b/net/ipv4/xfrm4_output.c
@@ -0,0 +1,141 @@
+/*
+ * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
+ * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <net/inet_ecn.h>
+#include <net/ip.h>
+#include <net/xfrm.h>
+#include <net/icmp.h>
+
+/* Add encapsulation header.
+ *
+ * In transport mode, the IP header will be moved forward to make space
+ * for the encapsulation header.
+ *
+ * In tunnel mode, 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 void xfrm4_encap(struct sk_buff *skb)
+{
+        struct dst_entry *dst = skb->dst;
+        struct xfrm_state *x = dst->xfrm;
+        struct iphdr *iph, *top_iph;
+
+        iph = skb->nh.iph;
+        skb->h.ipiph = iph;
+
+        skb->nh.raw = skb_push(skb, x->props.header_len);
+        top_iph = skb->nh.iph;
+
+        if (!x->props.mode) {
+                skb->h.raw += iph->ihl*4;
+                memmove(top_iph, iph, iph->ihl*4);
+                return;
+        }
+
+        top_iph->ihl = 5;
+        top_iph->version = 4;
+
+        /* DS disclosed */
+        top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
+        if (x->props.flags & XFRM_STATE_NOECN)
+                IP_ECN_clear(top_iph);
+
+        top_iph->frag_off = iph->frag_off & htons(IP_DF);
+        if (!top_iph->frag_off)
+                __ip_select_ident(top_iph, dst, 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));
+}
+
+static int xfrm4_tunnel_check_size(struct sk_buff *skb)
+{
+        int mtu, ret = 0;
+        struct dst_entry *dst;
+        struct iphdr *iph = skb->nh.iph;
+
+        if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
+                goto out;
+
+        IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
+        
+        if (!(iph->frag_off & htons(IP_DF)) || skb->local_df)
+                goto out;
+
+        dst = skb->dst;
+        mtu = dst_mtu(dst);
+        if (skb->len > mtu) {
+                icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
+                ret = -EMSGSIZE;
+        }
+out:
+        return ret;
+}
+
+int xfrm4_output(struct sk_buff *skb)
+{
+        struct dst_entry *dst = skb->dst;
+        struct xfrm_state *x = dst->xfrm;
+        int err;
+        
+        if (skb->ip_summed == CHECKSUM_HW) {
+                err = skb_checksum_help(skb, 0);
+                if (err)
+                        goto error_nolock;
+        }
+
+        if (x->props.mode) {
+                err = xfrm4_tunnel_check_size(skb);
+                if (err)
+                        goto error_nolock;
+        }
+
+        spin_lock_bh(&x->lock);
+        err = xfrm_state_check(x, skb);
+        if (err)
+                goto error;
+
+        xfrm4_encap(skb);
+
+        err = x->type->output(x, skb);
+        if (err)
+                goto error;
+
+        x->curlft.bytes += skb->len;
+        x->curlft.packets++;
+
+        spin_unlock_bh(&x->lock);
+        
+        if (!(skb->dst = dst_pop(dst))) {
+                err = -EHOSTUNREACH;
+                goto error_nolock;
+        }
+        err = NET_XMIT_BYPASS;
+
+out_exit:
+        return err;
+error:
+        spin_unlock_bh(&x->lock);
+error_nolock:
+        kfree_skb(skb);
+        goto out_exit;
+}