summaryrefslogtreecommitdiffstats
path: root/net/ipv4/xfrm4_output.c
diff options
context:
space:
mode:
Diffstat (limited to 'net/ipv4/xfrm4_output.c')
-rw-r--r--net/ipv4/xfrm4_output.c141
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;
+}