xfrm6_output.c

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/*
 * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
 * Copyright (C) 2002 USAGI/WIDE Project
 * Copyright (c) 2004 Herbert Xu <[email protected]>
 *
 * 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/if_ether.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmpv6.h>
#include <linux/netfilter_ipv6.h>
#include <net/dst.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <net/xfrm.h>

int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
              u8 **prevhdr)
{
    return ip6_find_1stfragopt(skb, prevhdr);
}

EXPORT_SYMBOL(xfrm6_find_1stfragopt);

static int xfrm6_local_dontfrag(struct sk_buff *skb)
{
    int proto;
    struct sock *sk = skb->sk;

    if (sk) {
        proto = sk->sk_protocol;

        if (proto == IPPROTO_UDP || proto == IPPROTO_RAW)
            return inet6_sk(sk)->dontfrag;
    }

    return 0;
}

static void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
{
    struct flowi6 fl6;
    struct sock *sk = skb->sk;

    fl6.flowi6_oif = sk->sk_bound_dev_if;
    fl6.daddr = ipv6_hdr(skb)->daddr;

    ipv6_local_rxpmtu(sk, &fl6, mtu);
}

static void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
{
    struct flowi6 fl6;
    struct sock *sk = skb->sk;

    fl6.fl6_dport = inet_sk(sk)->inet_dport;
    fl6.daddr = ipv6_hdr(skb)->daddr;

    ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
}

static int xfrm6_tunnel_check_size(struct sk_buff *skb)
{
    int mtu, ret = 0;
    struct dst_entry *dst = skb_dst(skb);

    mtu = dst_mtu(dst);
    if (mtu < IPV6_MIN_MTU)
        mtu = IPV6_MIN_MTU;

    if (!skb->local_df && skb->len > mtu) {
        skb->dev = dst->dev;

        if (xfrm6_local_dontfrag(skb))
            xfrm6_local_rxpmtu(skb, mtu);
        else if (skb->sk)
            xfrm6_local_error(skb, mtu);
        else
            icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
        ret = -EMSGSIZE;
    }

    return ret;
}

int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
{
    int err;

    err = xfrm6_tunnel_check_size(skb);
    if (err)
        return err;

    XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;

    return xfrm6_extract_header(skb);
}

int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
{
    int err;

    err = xfrm_inner_extract_output(x, skb);
    if (err)
        return err;

    memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
#ifdef CONFIG_NETFILTER
    IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
#endif

    skb->protocol = htons(ETH_P_IPV6);
    skb->local_df = 1;

    return x->outer_mode->output2(x, skb);
}
EXPORT_SYMBOL(xfrm6_prepare_output);

int xfrm6_output_finish(struct sk_buff *skb)
{
#ifdef CONFIG_NETFILTER
    IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
#endif

    skb->protocol = htons(ETH_P_IPV6);
    return xfrm_output(skb);
}

static int __xfrm6_output(struct sk_buff *skb)
{
    struct dst_entry *dst = skb_dst(skb);
    struct xfrm_state *x = dst->xfrm;
    int mtu = ip6_skb_dst_mtu(skb);

    if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {
        xfrm6_local_rxpmtu(skb, mtu);
        return -EMSGSIZE;
    } else if (!skb->local_df && skb->len > mtu && skb->sk) {
        xfrm6_local_error(skb, mtu);
        return -EMSGSIZE;
    }

    if (x->props.mode == XFRM_MODE_TUNNEL &&
        ((skb->len > mtu && !skb_is_gso(skb)) ||
        dst_allfrag(skb_dst(skb)))) {
            return ip6_fragment(skb, x->outer_mode->afinfo->output_finish);
    }
    return x->outer_mode->afinfo->output_finish(skb);
}

int xfrm6_output(struct sk_buff *skb)
{
    return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, skb, NULL,
               skb_dst(skb)->dev, __xfrm6_output);
}