[XFRM]: BEET mode

This patch introduces the BEET mode (Bound End-to-End Tunnel) with as
specified by the ietf draft at the following link:

http://www.ietf.org/internet-drafts/draft-nikander-esp-beet-mode-06.txt

The patch provides only single family support (i.e. inner family =
outer family).

Signed-off-by: Diego Beltrami <diego.beltrami@gmail.com>
Signed-off-by: Miika Komu     <miika@iki.fi>
Signed-off-by: Herbert Xu     <herbert@gondor.apana.org.au>
Signed-off-by: Abhinav Pathak <abhinav.pathak@hiit.fi>
Signed-off-by: Jeff Ahrenholz <ahrenholz@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 172 insertions, 8 deletions

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index d172a9804448..5572071af735 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -434,6 +434,15 @@ config INET_XFRM_MODE_TUNNEL
 
           If unsure, say Y.
 
+config INET_XFRM_MODE_BEET
+        tristate "IP: IPsec BEET mode"
+        default y
+        select XFRM
+        ---help---
+          Support for IPsec BEET mode.
+
+          If unsure, say Y.
+
 config INET_DIAG
         tristate "INET: socket monitoring interface"
         default y
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index f66049e28aeb..15645c51520c 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_INET_AH) += ah4.o
 obj-$(CONFIG_INET_ESP) += esp4.o
 obj-$(CONFIG_INET_IPCOMP) += ipcomp.o
 obj-$(CONFIG_INET_XFRM_TUNNEL) += xfrm4_tunnel.o
+obj-$(CONFIG_INET_XFRM_MODE_BEET) += xfrm4_mode_beet.o
 obj-$(CONFIG_INET_TUNNEL) += tunnel4.o
 obj-$(CONFIG_INET_XFRM_MODE_TRANSPORT) += xfrm4_mode_transport.o
 obj-$(CONFIG_INET_XFRM_MODE_TUNNEL) += xfrm4_mode_tunnel.o
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 13b29360d102..b5c205b57669 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -253,7 +253,8 @@ static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
                  *    as per draft-ietf-ipsec-udp-encaps-06,
                  *    section 3.1.2
                  */
-                if (x->props.mode == XFRM_MODE_TRANSPORT)
+                if (x->props.mode == XFRM_MODE_TRANSPORT ||
+                    x->props.mode == XFRM_MODE_BEET)
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
         }
 
@@ -271,17 +272,28 @@ static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
 {
         struct esp_data *esp = x->data;
         u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
-
-        if (x->props.mode == XFRM_MODE_TUNNEL) {
-                mtu = ALIGN(mtu + 2, blksize);
-        } else {
-                /* The worst case. */
+        int enclen = 0;
+
+        switch (x->props.mode) {
+        case XFRM_MODE_TUNNEL:
+                mtu = ALIGN(mtu +2, blksize);
+                break;
+        default:
+        case XFRM_MODE_TRANSPORT:
+                /* The worst case */
                 mtu = ALIGN(mtu + 2, 4) + blksize - 4;
+                break;
+        case XFRM_MODE_BEET:
+                /* The worst case. */
+                enclen = IPV4_BEET_PHMAXLEN;
+                mtu = ALIGN(mtu + enclen + 2, blksize);
+                break;
         }
+
         if (esp->conf.padlen)
                 mtu = ALIGN(mtu, esp->conf.padlen);
 
-        return mtu + x->props.header_len + esp->auth.icv_trunc_len;
+        return mtu + x->props.header_len + esp->auth.icv_trunc_len - enclen;
 }
 
 static void esp4_err(struct sk_buff *skb, u32 info)
diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 2017d36024d4..3839b706142e 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -206,6 +206,7 @@ static void ipcomp4_err(struct sk_buff *skb, u32 info)
 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
 {
         struct xfrm_state *t;
+        u8 mode = XFRM_MODE_TUNNEL;
         
         t = xfrm_state_alloc();
         if (t == NULL)
@@ -216,7 +217,9 @@ static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
         t->id.daddr.a4 = x->id.daddr.a4;
         memcpy(&t->sel, &x->sel, sizeof(t->sel));
         t->props.family = AF_INET;
-        t->props.mode = XFRM_MODE_TUNNEL;
+        if (x->props.mode == XFRM_MODE_BEET)
+                mode = x->props.mode;
+        t->props.mode = mode;
         t->props.saddr.a4 = x->props.saddr.a4;
         t->props.flags = x->props.flags;
 
diff --git a/net/ipv4/xfrm4_mode_beet.c b/net/ipv4/xfrm4_mode_beet.c
new file mode 100644
index 000000000000..89cf59ea7bbe
--- /dev/null
+++ b/net/ipv4/xfrm4_mode_beet.c
@@ -0,0 +1,139 @@
+/*
+ * xfrm4_mode_beet.c - BEET mode encapsulation for IPv4.
+ *
+ * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com>
+ *                    Miika Komu     <miika@iki.fi>
+ *                    Herbert Xu     <herbert@gondor.apana.org.au>
+ *                    Abhinav Pathak <abhinav.pathak@hiit.fi>
+ *                    Jeff Ahrenholz <ahrenholz@gmail.com>
+ */
+
+#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/ip.h>
+#include <net/xfrm.h>
+
+/* Add encapsulation header.
+ *
+ * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
+ * 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_beet_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+        struct iphdr *iph, *top_iph = NULL;
+        int hdrlen, optlen;
+
+        iph = skb->nh.iph;
+        skb->h.ipiph = iph;
+
+        hdrlen = 0;
+        optlen = iph->ihl * 4 - sizeof(*iph);
+        if (unlikely(optlen))
+                hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
+
+        skb->nh.raw = skb_push(skb, x->props.header_len + hdrlen);
+        top_iph = skb->nh.iph;
+        hdrlen = iph->ihl * 4 - optlen;
+        skb->h.raw += hdrlen;
+
+        memmove(top_iph, iph, hdrlen);
+        if (unlikely(optlen)) {
+                struct ip_beet_phdr *ph;
+
+                BUG_ON(optlen < 0);
+
+                ph = (struct ip_beet_phdr *)skb->h.raw;
+                ph->padlen = 4 - (optlen & 4);
+                ph->hdrlen = (optlen + ph->padlen + sizeof(*ph)) / 8;
+                ph->nexthdr = top_iph->protocol;
+
+                top_iph->protocol = IPPROTO_BEETPH;
+                top_iph->ihl = sizeof(struct iphdr) / 4;
+        }
+
+        top_iph->saddr = x->props.saddr.a4;
+        top_iph->daddr = x->id.daddr.a4;
+
+        return 0;
+}
+
+static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+        struct iphdr *iph = skb->nh.iph;
+        int phlen = 0;
+        int optlen = 0;
+        __u8 ph_nexthdr = 0, protocol = 0;
+        int err = -EINVAL;
+
+        protocol = iph->protocol;
+
+        if (unlikely(iph->protocol == IPPROTO_BEETPH)) {
+                struct ip_beet_phdr *ph = (struct ip_beet_phdr*)(iph + 1);
+
+                if (!pskb_may_pull(skb, sizeof(*ph)))
+                        goto out;
+
+                phlen = ph->hdrlen * 8;
+                optlen = phlen - ph->padlen - sizeof(*ph);
+                if (optlen < 0 || optlen & 3 || optlen > 250)
+                        goto out;
+
+                if (!pskb_may_pull(skb, phlen))
+                        goto out;
+
+                ph_nexthdr = ph->nexthdr;
+        }
+
+        skb_push(skb, sizeof(*iph) - phlen + optlen);
+        memmove(skb->data, skb->nh.raw, sizeof(*iph));
+        skb->nh.raw = skb->data;
+
+        iph = skb->nh.iph;
+        iph->ihl = (sizeof(*iph) + optlen) / 4;
+        iph->tot_len = htons(skb->len);
+        iph->daddr = x->sel.daddr.a4;
+        iph->saddr = x->sel.saddr.a4;
+        if (ph_nexthdr)
+                iph->protocol = ph_nexthdr;
+        else
+                iph->protocol = protocol;
+        iph->check = 0;
+        iph->check = ip_fast_csum(skb->nh.raw, iph->ihl);
+        err = 0;
+out:
+        return err;
+}
+
+static struct xfrm_mode xfrm4_beet_mode = {
+        .input = xfrm4_beet_input,
+        .output = xfrm4_beet_output,
+        .owner = THIS_MODULE,
+        .encap = XFRM_MODE_BEET,
+};
+
+static int __init xfrm4_beet_init(void)
+{
+        return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
+}
+
+static void __exit xfrm4_beet_exit(void)
+{
+        int err;
+
+        err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
+        BUG_ON(err);
+}
+
+module_init(xfrm4_beet_init);
+module_exit(xfrm4_beet_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);