Ejemplo n.º 1
0
/* This function assumes it is being called from dev_queue_xmit()
 * and that skb is filled properly by that function.
 */
static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct ip_tunnel *tunnel = netdev_priv(dev);
	struct flowi fl;

	memset(&fl, 0, sizeof(fl));

	switch (skb->protocol) {
	case htons(ETH_P_IP):
		xfrm_decode_session(skb, &fl, AF_INET);
		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
		break;
	case htons(ETH_P_IPV6):
		xfrm_decode_session(skb, &fl, AF_INET6);
		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
		break;
	default:
		dev->stats.tx_errors++;
		dev_kfree_skb(skb);
		return NETDEV_TX_OK;
	}

	/* override mark with tunnel output key */
	fl.flowi_mark = be32_to_cpu(tunnel->parms.o_key);

	return vti_xmit(skb, dev, &fl);
}
Ejemplo n.º 2
0
int ip_xfrm_me_harder(struct sk_buff *skb)
{
    struct flowi fl;
    unsigned int hh_len;
    struct dst_entry *dst;

    if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
        return 0;
    if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
        return -1;

    dst = skb->dst;
    if (dst->xfrm)
        dst = ((struct xfrm_dst *)dst)->route;
    dst_hold(dst);

    if (xfrm_lookup(&dst, &fl, skb->sk, 0) < 0)
        return -1;

    dst_release(skb->dst);
    skb->dst = dst;

    /* Change in oif may mean change in hh_len. */
    hh_len = skb->dst->dev->hard_header_len;
    if (skb_headroom(skb) < hh_len &&
        pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
        return -1;
    return 0;
}
Ejemplo n.º 3
0
int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family)
{
	struct flowi fl;
	unsigned int hh_len;
	struct dst_entry *dst;
	int err;

	err = xfrm_decode_session(skb, &fl, family);
	if (err < 0)
		return err;

	dst = skb_dst(skb);
	if (dst->xfrm)
		dst = ((struct xfrm_dst *)dst)->route;
	dst_hold(dst);

	dst = xfrm_lookup(net, dst, &fl, skb->sk, 0);
	if (IS_ERR(dst))
		return PTR_ERR(dst);

	skb_dst_drop(skb);
	skb_dst_set(skb, dst);

	/* Change in oif may mean change in hh_len. */
	hh_len = skb_dst(skb)->dev->hard_header_len;
	if (skb_headroom(skb) < hh_len &&
	    pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
		return -ENOMEM;
	return 0;
}
Ejemplo n.º 4
0
/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
{
	struct net *net = dev_net(skb_dst(skb)->dev);
	const struct iphdr *iph = ip_hdr(skb);
	struct rtable *rt;
	struct flowi4 fl4 = {};
	__be32 saddr = iph->saddr;
	__u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
	unsigned int hh_len;

	if (addr_type == RTN_UNSPEC)
		addr_type = inet_addr_type(net, saddr);
	if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
		flags |= FLOWI_FLAG_ANYSRC;
	else
		saddr = 0;

	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
	 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
	 */
	fl4.daddr = iph->daddr;
	fl4.saddr = saddr;
	fl4.flowi4_tos = RT_TOS(iph->tos);
	fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
	fl4.flowi4_mark = skb->mark;
	fl4.flowi4_flags = flags;
	rt = ip_route_output_key(net, &fl4);
	if (IS_ERR(rt))
		return -1;

	/* Drop old route. */
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);

	if (skb_dst(skb)->error)
		return -1;

#ifdef CONFIG_XFRM
	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
		struct dst_entry *dst = skb_dst(skb);
		skb_dst_set(skb, NULL);
		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
		if (IS_ERR(dst))
			return -1;
		skb_dst_set(skb, dst);
	}
#endif

	/* Change in oif may mean change in hh_len. */
	hh_len = skb_dst(skb)->dev->hard_header_len;
	if (skb_headroom(skb) < hh_len &&
	    pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
				0, GFP_ATOMIC))
		return -1;

	return 0;
}
Ejemplo n.º 5
0
int ip6_route_me_harder(struct sk_buff *skb)
{
	struct ipv6hdr *iph = skb->nh.ipv6h;
	struct dst_entry *dst;
	struct flowi fl = {
		.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
		.iif = ((struct inet6_skb_parm *)skb->cb)->iif,
		.nl_u =
		{ .ip6_u =
		  { .daddr = iph->daddr,
		    .saddr = iph->saddr,
		    .flowlabel = (* (__u32 *) iph)&IPV6_FLOWINFO_MASK, } },
	};

	dst = ip6_route_output(skb->sk, &fl);

#ifdef CONFIG_XFRM
	if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(skb, &fl, AF_INET6) == 0)
		if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
			return -1;
#endif

	if (dst->error) {
#ifdef CONFIG_IPV6_STATISTICS
		struct inet6_dev *idev = ((struct rt6_info *)dst)->rt6i_idev;
		IP6_INC_STATS(idev, IPSTATS_MIB_OUTNOROUTES);
#else
		IP6_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
#endif
		LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
		dst_release(dst);
		return -EINVAL;
	}

	/* Drop old route. */
	dst_release(skb->dst);

	skb->dst = dst;
	return 0;
}
Ejemplo n.º 6
0
int ip6_route_me_harder(struct sk_buff *skb)
{
	struct net *net = dev_net(skb_dst(skb)->dev);
	struct ipv6hdr *iph = ipv6_hdr(skb);
	struct dst_entry *dst;
	struct flowi fl = {
		.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
		.mark = skb->mark,
		.nl_u =
		{ .ip6_u =
		  { .daddr = iph->daddr,
		    .saddr = iph->saddr, } },
	};

	dst = ip6_route_output(net, skb->sk, &fl);
	if (dst->error) {
		IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
		LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
		dst_release(dst);
		return -EINVAL;
	}

	/* Drop old route. */
	skb_dst_drop(skb);

	skb_dst_set(skb, dst);

#ifdef CONFIG_XFRM
	if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(skb, &fl, AF_INET6) == 0) {
		skb_dst_set(skb, NULL);
		if (xfrm_lookup(net, &dst, &fl, skb->sk, 0))
			return -1;
		skb_dst_set(skb, dst);
	}
#endif

	return 0;
}
Ejemplo n.º 7
0
int ip_xfrm_me_harder(struct sk_buff **pskb)
{
	struct flowi fl;
	unsigned int hh_len;
	struct dst_entry *dst;

	if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED)
		return 0;
	if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0)
		return -1;

	dst = (*pskb)->dst;
	if (dst->xfrm)
		dst = ((struct xfrm_dst *)dst)->route;
	dst_hold(dst);

	if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0)
		return -1;

	dst_release((*pskb)->dst);
	(*pskb)->dst = dst;

	/* Change in oif may mean change in hh_len. */
	hh_len = (*pskb)->dst->dev->hard_header_len;
	if (skb_headroom(*pskb) < hh_len) {
		struct sk_buff *nskb;

		nskb = skb_realloc_headroom(*pskb, hh_len);
		if (!nskb)
			return -1;
		if ((*pskb)->sk)
			skb_set_owner_w(nskb, (*pskb)->sk);
		kfree_skb(*pskb);
		*pskb = nskb;
	}
	return 0;
}
Ejemplo n.º 8
0
int ip6_route_me_harder(struct sk_buff *skb)
{
    struct ipv6hdr *iph = skb->nh.ipv6h;
    struct dst_entry *dst;
    struct flowi fl = {
        .oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
        .nl_u =
        {   .ip6_u =
            {   .daddr = iph->daddr,
                .saddr = iph->saddr,
            }
        },
    };

    dst = ip6_route_output(skb->sk, &fl);

#ifdef CONFIG_XFRM
    if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
            xfrm_decode_session(skb, &fl, AF_INET6) == 0)
        if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
            return -1;
#endif

    if (dst->error) {
        IP6_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
        LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
        dst_release(dst);
        return -EINVAL;
    }

    /* Drop old route. */
    dst_release(skb->dst);

    skb->dst = dst;
    return 0;
}
int ip6_route_me_harder(struct sk_buff *skb)
{
    struct net *net = dev_net(skb_dst(skb)->dev);
    struct ipv6hdr *iph = ipv6_hdr(skb);
    struct dst_entry *dst;
    struct flowi fl = {
        .oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
        .mark = skb->mark,
        .fl6_dst = iph->daddr,
        .fl6_src = iph->saddr,
    };

    dst = ip6_route_output(net, skb->sk, &fl);
    if (dst->error) {
        IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
        LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
        dst_release(dst);
        return -EINVAL;
    }

    /* Drop old route. */
    skb_dst_drop(skb);

    skb_dst_set(skb, dst);

#ifdef CONFIG_XFRM
    if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
            xfrm_decode_session(skb, &fl, AF_INET6) == 0) {
        skb_dst_set(skb, NULL);
        if (xfrm_lookup(net, &dst, &fl, skb->sk, 0))
            return -1;
        skb_dst_set(skb, dst);
    }
#endif

    return 0;
}
EXPORT_SYMBOL(ip6_route_me_harder);

/*
 * Extra routing may needed on local out, as the QUEUE target never
 * returns control to the table.
 */

struct ip6_rt_info {
    struct in6_addr daddr;
    struct in6_addr saddr;
    u_int32_t mark;
};

static void nf_ip6_saveroute(const struct sk_buff *skb,
                             struct nf_queue_entry *entry)
{
    struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);

    if (entry->hook == NF_INET_LOCAL_OUT) {
        struct ipv6hdr *iph = ipv6_hdr(skb);

        rt_info->daddr = iph->daddr;
        rt_info->saddr = iph->saddr;
        rt_info->mark = skb->mark;
    }
}

static int nf_ip6_reroute(struct sk_buff *skb,
                          const struct nf_queue_entry *entry)
{
    struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);

    if (entry->hook == NF_INET_LOCAL_OUT) {
        struct ipv6hdr *iph = ipv6_hdr(skb);
        if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
                !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
                skb->mark != rt_info->mark)
            return ip6_route_me_harder(skb);
    }
    return 0;
}

static int nf_ip6_route(struct dst_entry **dst, struct flowi *fl)
{
    *dst = ip6_route_output(&init_net, NULL, fl);
    return (*dst)->error;
}
Ejemplo n.º 10
0
int ip6_route_me_harder(struct sk_buff *skb)
{
	struct net *net = dev_net(skb_dst(skb)->dev);
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	unsigned int hh_len;
	struct dst_entry *dst;
	struct flowi6 fl6 = {
		.flowi6_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
		.flowi6_mark = skb->mark,
		.daddr = iph->daddr,
		.saddr = iph->saddr,
	};
	int err;

	dst = ip6_route_output(net, skb->sk, &fl6);
	err = dst->error;
	if (err) {
		IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
		net_dbg_ratelimited("ip6_route_me_harder: No more route\n");
		dst_release(dst);
		return err;
	}

	/* Drop old route. */
	skb_dst_drop(skb);

	skb_dst_set(skb, dst);

#ifdef CONFIG_XFRM
	if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
		skb_dst_set(skb, NULL);
		dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0);
		if (IS_ERR(dst))
			return PTR_ERR(dst);
		skb_dst_set(skb, dst);
	}
#endif

	/* Change in oif may mean change in hh_len. */
	hh_len = skb_dst(skb)->dev->hard_header_len;
	if (skb_headroom(skb) < hh_len &&
	    pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
			     0, GFP_ATOMIC))
		return -ENOMEM;

	return 0;
}
EXPORT_SYMBOL(ip6_route_me_harder);

/*
 * Extra routing may needed on local out, as the QUEUE target never
 * returns control to the table.
 */

struct ip6_rt_info {
	struct in6_addr daddr;
	struct in6_addr saddr;
	u_int32_t mark;
};

static void nf_ip6_saveroute(const struct sk_buff *skb,
			     struct nf_queue_entry *entry)
{
	struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);

	if (entry->hook == NF_INET_LOCAL_OUT) {
		const struct ipv6hdr *iph = ipv6_hdr(skb);

		rt_info->daddr = iph->daddr;
		rt_info->saddr = iph->saddr;
		rt_info->mark = skb->mark;
	}
}

static int nf_ip6_reroute(struct sk_buff *skb,
			  const struct nf_queue_entry *entry)
{
	struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);

	if (entry->hook == NF_INET_LOCAL_OUT) {
		const struct ipv6hdr *iph = ipv6_hdr(skb);
		if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
		    !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
		    skb->mark != rt_info->mark)
			return ip6_route_me_harder(skb);
	}
	return 0;
}

static int nf_ip6_route(struct net *net, struct dst_entry **dst,
			struct flowi *fl, bool strict)
{
	static const struct ipv6_pinfo fake_pinfo;
	static const struct inet_sock fake_sk = {
		/* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
		.sk.sk_bound_dev_if = 1,
		.pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
	};
	const void *sk = strict ? &fake_sk : NULL;
	struct dst_entry *result;
	int err;

	result = ip6_route_output(net, sk, &fl->u.ip6);
	err = result->error;
	if (err)
		dst_release(result);
	else
		*dst = result;
	return err;
}

__sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
			     unsigned int dataoff, u_int8_t protocol)
{
	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
	__sum16 csum = 0;

	switch (skb->ip_summed) {
	case CHECKSUM_COMPLETE:
		if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
			break;
		if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
				     skb->len - dataoff, protocol,
				     csum_sub(skb->csum,
					      skb_checksum(skb, 0,
							   dataoff, 0)))) {
			skb->ip_summed = CHECKSUM_UNNECESSARY;
			break;
		}
		/* fall through */
	case CHECKSUM_NONE:
		skb->csum = ~csum_unfold(
				csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
					     skb->len - dataoff,
					     protocol,
					     csum_sub(0,
						      skb_checksum(skb, 0,
								   dataoff, 0))));
		csum = __skb_checksum_complete(skb);
	}
	return csum;
}
EXPORT_SYMBOL(nf_ip6_checksum);

static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
				       unsigned int dataoff, unsigned int len,
				       u_int8_t protocol)
{
	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
	__wsum hsum;
	__sum16 csum = 0;

	switch (skb->ip_summed) {
	case CHECKSUM_COMPLETE:
		if (len == skb->len - dataoff)
			return nf_ip6_checksum(skb, hook, dataoff, protocol);
		/* fall through */
	case CHECKSUM_NONE:
		hsum = skb_checksum(skb, 0, dataoff, 0);
		skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
							 &ip6h->daddr,
							 skb->len - dataoff,
							 protocol,
							 csum_sub(0, hsum)));
		skb->ip_summed = CHECKSUM_NONE;
		return __skb_checksum_complete_head(skb, dataoff + len);
	}
	return csum;
};

static const struct nf_ipv6_ops ipv6ops = {
	.chk_addr	= ipv6_chk_addr,
};

static const struct nf_afinfo nf_ip6_afinfo = {
	.family			= AF_INET6,
	.checksum		= nf_ip6_checksum,
	.checksum_partial	= nf_ip6_checksum_partial,
	.route			= nf_ip6_route,
	.saveroute		= nf_ip6_saveroute,
	.reroute		= nf_ip6_reroute,
	.route_key_size		= sizeof(struct ip6_rt_info),
};

int __init ipv6_netfilter_init(void)
{
	RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
	return nf_register_afinfo(&nf_ip6_afinfo);
}

/* This can be called from inet6_init() on errors, so it cannot
 * be marked __exit. -DaveM
 */
void ipv6_netfilter_fini(void)
{
	RCU_INIT_POINTER(nf_ipv6_ops, NULL);
	nf_unregister_afinfo(&nf_ip6_afinfo);
}
Ejemplo n.º 11
0
/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
{
    const struct iphdr *iph = ip_hdr(skb);
    struct rtable *rt;
    struct flowi fl = {};
    struct dst_entry *odst;
    unsigned int hh_len;
    unsigned int type;

    type = inet_addr_type(&init_net, iph->saddr);
    if (addr_type == RTN_UNSPEC)
        addr_type = type;

    /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
     * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
     */
    if (addr_type == RTN_LOCAL) {
        fl.nl_u.ip4_u.daddr = iph->daddr;
        if (type == RTN_LOCAL)
            fl.nl_u.ip4_u.saddr = iph->saddr;
        fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
        fl.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
        fl.mark = skb->mark;
        if (ip_route_output_key(&init_net, &rt, &fl) != 0)
            return -1;

        /* Drop old route. */
        dst_release(skb->dst);
        skb->dst = &rt->u.dst;
    } else {
        /* non-local src, find valid iif to satisfy
         * rp-filter when calling ip_route_input. */
        fl.nl_u.ip4_u.daddr = iph->saddr;
        if (ip_route_output_key(&init_net, &rt, &fl) != 0)
            return -1;

        odst = skb->dst;
        if (ip_route_input(skb, iph->daddr, iph->saddr,
                   RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
            dst_release(&rt->u.dst);
            return -1;
        }
        dst_release(&rt->u.dst);
        dst_release(odst);
    }

    if (skb->dst->error)
        return -1;

#ifdef CONFIG_XFRM
    if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
        xfrm_decode_session(skb, &fl, AF_INET) == 0)
        if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
            return -1;
#endif

    /* Change in oif may mean change in hh_len. */
    hh_len = skb->dst->dev->hard_header_len;
    if (skb_headroom(skb) < hh_len &&
        pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
        return -1;

    return 0;
}
Ejemplo n.º 12
0
/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
{
	struct net *net = dev_net(skb_dst(skb)->dev);
	const struct iphdr *iph = ip_hdr(skb);
	struct rtable *rt;
	struct flowi4 fl4 = {};
	unsigned long orefdst;
	unsigned int hh_len;
	unsigned int type;

	type = inet_addr_type(net, iph->saddr);
	if (skb->sk && inet_sk(skb->sk)->transparent)
		type = RTN_LOCAL;
	if (addr_type == RTN_UNSPEC)
		addr_type = type;

	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
	 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
	 */
	if (addr_type == RTN_LOCAL) {
		fl4.daddr = iph->daddr;
		if (type == RTN_LOCAL)
			fl4.saddr = iph->saddr;
		fl4.flowi4_tos = RT_TOS(iph->tos);
		fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
		fl4.flowi4_mark = skb->mark;
		fl4.flowi4_flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
		rt = ip_route_output_key(net, &fl4);
		if (IS_ERR(rt))
			return -1;

		/* Drop old route. */
		skb_dst_drop(skb);
		skb_dst_set(skb, &rt->dst);
	} else {
		/* non-local src, find valid iif to satisfy
		 * rp-filter when calling ip_route_input. */
		fl4.daddr = iph->saddr;
		rt = ip_route_output_key(net, &fl4);
		if (IS_ERR(rt))
			return -1;

		orefdst = skb->_skb_refdst;
		if (ip_route_input(skb, iph->daddr, iph->saddr,
				   RT_TOS(iph->tos), rt->dst.dev) != 0) {
			dst_release(&rt->dst);
			return -1;
		}
		dst_release(&rt->dst);
		refdst_drop(orefdst);
	}

	if (skb_dst(skb)->error)
		return -1;

#ifdef CONFIG_XFRM
	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
		struct dst_entry *dst = skb_dst(skb);
		skb_dst_set(skb, NULL);
		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
		if (IS_ERR(dst))
			return -1;
		skb_dst_set(skb, dst);
	}
#endif

	/* Change in oif may mean change in hh_len. */
	hh_len = skb_dst(skb)->dev->hard_header_len;
	if (skb_headroom(skb) < hh_len &&
	    pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
		return -1;

	return 0;
}