ip_output.c 37.6 KB
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/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		The Internet Protocol (IP) output module.
 *
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 * Authors:	Ross Biro
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 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *		Donald Becker, <becker@super.org>
 *		Alan Cox, <Alan.Cox@linux.org>
 *		Richard Underwood
 *		Stefan Becker, <stefanb@yello.ping.de>
 *		Jorge Cwik, <jorge@laser.satlink.net>
 *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 *		Hirokazu Takahashi, <taka@valinux.co.jp>
 *
 *	See ip_input.c for original log
 *
 *	Fixes:
 *		Alan Cox	:	Missing nonblock feature in ip_build_xmit.
 *		Mike Kilburn	:	htons() missing in ip_build_xmit.
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 *		Bradford Johnson:	Fix faulty handling of some frames when
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 *					no route is found.
 *		Alexander Demenshin:	Missing sk/skb free in ip_queue_xmit
 *					(in case if packet not accepted by
 *					output firewall rules)
 *		Mike McLagan	:	Routing by source
 *		Alexey Kuznetsov:	use new route cache
 *		Andi Kleen:		Fix broken PMTU recovery and remove
 *					some redundant tests.
 *	Vitaly E. Lavrov	:	Transparent proxy revived after year coma.
 *		Andi Kleen	: 	Replace ip_reply with ip_send_reply.
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 *		Andi Kleen	:	Split fast and slow ip_build_xmit path
 *					for decreased register pressure on x86
 *					and more readibility.
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 *		Marc Boucher	:	When call_out_firewall returns FW_QUEUE,
 *					silently drop skb instead of failing with -EPERM.
 *		Detlev Wengorz	:	Copy protocol for fragments.
 *		Hirokazu Takahashi:	HW checksumming for outgoing UDP
 *					datagrams.
 *		Hirokazu Takahashi:	sendfile() on UDP works now.
 */

#include <asm/uaccess.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/errno.h>
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#include <linux/highmem.h>
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#include <linux/slab.h>
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#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>

#include <net/snmp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
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#include <net/xfrm.h>
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#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/icmp.h>
#include <net/checksum.h>
#include <net/inetpeer.h>
#include <linux/igmp.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_bridge.h>
#include <linux/mroute.h>
#include <linux/netlink.h>
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#include <linux/tcp.h>
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int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
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EXPORT_SYMBOL(sysctl_ip_default_ttl);
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/* Generate a checksum for an outgoing IP datagram. */
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void ip_send_check(struct iphdr *iph)
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{
	iph->check = 0;
	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
}
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EXPORT_SYMBOL(ip_send_check);
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int __ip_local_out(struct sk_buff *skb)
{
	struct iphdr *iph = ip_hdr(skb);

	iph->tot_len = htons(skb->len);
	ip_send_check(iph);
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	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
		       skb_dst(skb)->dev, dst_output);
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}

int ip_local_out(struct sk_buff *skb)
{
	int err;

	err = __ip_local_out(skb);
	if (likely(err == 1))
		err = dst_output(skb);

	return err;
}
EXPORT_SYMBOL_GPL(ip_local_out);

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static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
{
	int ttl = inet->uc_ttl;

	if (ttl < 0)
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		ttl = ip4_dst_hoplimit(dst);
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	return ttl;
}

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/*
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 *		Add an ip header to a skbuff and send it out.
 *
 */
int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
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			  __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
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{
	struct inet_sock *inet = inet_sk(sk);
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	struct rtable *rt = skb_rtable(skb);
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	struct iphdr *iph;

	/* Build the IP header. */
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	skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
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	skb_reset_network_header(skb);
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	iph = ip_hdr(skb);
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	iph->version  = 4;
	iph->ihl      = 5;
	iph->tos      = inet->tos;
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	if (ip_dont_fragment(sk, &rt->dst))
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		iph->frag_off = htons(IP_DF);
	else
		iph->frag_off = 0;
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	iph->ttl      = ip_select_ttl(inet, &rt->dst);
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	iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
	iph->saddr    = saddr;
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	iph->protocol = sk->sk_protocol;
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	ip_select_ident(iph, &rt->dst, sk);
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	if (opt && opt->opt.optlen) {
		iph->ihl += opt->opt.optlen>>2;
		ip_options_build(skb, &opt->opt, daddr, rt, 0);
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	}

	skb->priority = sk->sk_priority;
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	skb->mark = sk->sk_mark;
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	/* Send it out. */
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	return ip_local_out(skb);
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}
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EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);

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static inline int ip_finish_output2(struct sk_buff *skb)
{
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	struct dst_entry *dst = skb_dst(skb);
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	struct rtable *rt = (struct rtable *)dst;
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	struct net_device *dev = dst->dev;
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	unsigned int hh_len = LL_RESERVED_SPACE(dev);
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	struct neighbour *neigh;
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	u32 nexthop;
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	if (rt->rt_type == RTN_MULTICAST) {
		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
	} else if (rt->rt_type == RTN_BROADCAST)
		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);
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	/* Be paranoid, rather than too clever. */
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	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
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		struct sk_buff *skb2;

		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
		if (skb2 == NULL) {
			kfree_skb(skb);
			return -ENOMEM;
		}
		if (skb->sk)
			skb_set_owner_w(skb2, skb->sk);
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		consume_skb(skb);
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		skb = skb2;
	}

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	rcu_read_lock_bh();
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	nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
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	neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
	if (unlikely(!neigh))
		neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
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	if (!IS_ERR(neigh)) {
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		int res = dst_neigh_output(dst, neigh, skb);
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		rcu_read_unlock_bh();
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		return res;
	}
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	rcu_read_unlock_bh();
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	net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
			    __func__);
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	kfree_skb(skb);
	return -EINVAL;
}

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static int ip_finish_output(struct sk_buff *skb)
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{
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#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
	/* Policy lookup after SNAT yielded a new policy */
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	if (skb_dst(skb)->xfrm != NULL) {
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		IPCB(skb)->flags |= IPSKB_REROUTED;
		return dst_output(skb);
	}
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#endif
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	if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
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		return ip_fragment(skb, ip_finish_output2);
	else
		return ip_finish_output2(skb);
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}

int ip_mc_output(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;
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	struct rtable *rt = skb_rtable(skb);
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	struct net_device *dev = rt->dst.dev;
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	/*
	 *	If the indicated interface is up and running, send the packet.
	 */
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	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
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	skb->dev = dev;
	skb->protocol = htons(ETH_P_IP);

	/*
	 *	Multicasts are looped back for other local users
	 */

	if (rt->rt_flags&RTCF_MULTICAST) {
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		if (sk_mc_loop(sk)
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#ifdef CONFIG_IP_MROUTE
		/* Small optimization: do not loopback not local frames,
		   which returned after forwarding; they will be  dropped
		   by ip_mr_input in any case.
		   Note, that local frames are looped back to be delivered
		   to local recipients.

		   This check is duplicated in ip_mr_input at the moment.
		 */
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		    &&
		    ((rt->rt_flags & RTCF_LOCAL) ||
		     !(IPCB(skb)->flags & IPSKB_FORWARDED))
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#endif
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		   ) {
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			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
			if (newskb)
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				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
					newskb, NULL, newskb->dev,
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					dev_loopback_xmit);
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		}

		/* Multicasts with ttl 0 must not go beyond the host */

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		if (ip_hdr(skb)->ttl == 0) {
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			kfree_skb(skb);
			return 0;
		}
	}

	if (rt->rt_flags&RTCF_BROADCAST) {
		struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
		if (newskb)
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			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
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				NULL, newskb->dev, dev_loopback_xmit);
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	}

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	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
			    skb->dev, ip_finish_output,
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			    !(IPCB(skb)->flags & IPSKB_REROUTED));
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}

int ip_output(struct sk_buff *skb)
{
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	struct net_device *dev = skb_dst(skb)->dev;
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	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
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	skb->dev = dev;
	skb->protocol = htons(ETH_P_IP);

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	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
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			    ip_finish_output,
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			    !(IPCB(skb)->flags & IPSKB_REROUTED));
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}

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/*
 * copy saddr and daddr, possibly using 64bit load/stores
 * Equivalent to :
 *   iph->saddr = fl4->saddr;
 *   iph->daddr = fl4->daddr;
 */
static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
{
	BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
		     offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
	memcpy(&iph->saddr, &fl4->saddr,
	       sizeof(fl4->saddr) + sizeof(fl4->daddr));
}

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int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
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{
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	struct sock *sk = skb->sk;
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	struct inet_sock *inet = inet_sk(sk);
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	struct ip_options_rcu *inet_opt;
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	struct flowi4 *fl4;
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	struct rtable *rt;
	struct iphdr *iph;
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	int res;
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	/* Skip all of this if the packet is already routed,
	 * f.e. by something like SCTP.
	 */
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	rcu_read_lock();
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	inet_opt = rcu_dereference(inet->inet_opt);
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	fl4 = &fl->u.ip4;
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	rt = skb_rtable(skb);
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	if (rt != NULL)
		goto packet_routed;

	/* Make sure we can route this packet. */
	rt = (struct rtable *)__sk_dst_check(sk, 0);
	if (rt == NULL) {
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		__be32 daddr;
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		/* Use correct destination address if we have options. */
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		daddr = inet->inet_daddr;
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		if (inet_opt && inet_opt->opt.srr)
			daddr = inet_opt->opt.faddr;
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		/* If this fails, retransmit mechanism of transport layer will
		 * keep trying until route appears or the connection times
		 * itself out.
		 */
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		rt = ip_route_output_ports(sock_net(sk), fl4, sk,
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					   daddr, inet->inet_saddr,
					   inet->inet_dport,
					   inet->inet_sport,
					   sk->sk_protocol,
					   RT_CONN_FLAGS(sk),
					   sk->sk_bound_dev_if);
		if (IS_ERR(rt))
			goto no_route;
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		sk_setup_caps(sk, &rt->dst);
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	}
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	skb_dst_set_noref(skb, &rt->dst);
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packet_routed:
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	if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
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		goto no_route;

	/* OK, we know where to send it, allocate and build IP header. */
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	skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
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	skb_reset_network_header(skb);
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	iph = ip_hdr(skb);
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	*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
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	if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
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		iph->frag_off = htons(IP_DF);
	else
		iph->frag_off = 0;
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	iph->ttl      = ip_select_ttl(inet, &rt->dst);
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	iph->protocol = sk->sk_protocol;
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	ip_copy_addrs(iph, fl4);

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	/* Transport layer set skb->h.foo itself. */

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	if (inet_opt && inet_opt->opt.optlen) {
		iph->ihl += inet_opt->opt.optlen >> 2;
		ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
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	}

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	ip_select_ident_more(iph, &rt->dst, sk,
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			     (skb_shinfo(skb)->gso_segs ?: 1) - 1);
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	skb->priority = sk->sk_priority;
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	skb->mark = sk->sk_mark;
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	res = ip_local_out(skb);
	rcu_read_unlock();
	return res;
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no_route:
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	rcu_read_unlock();
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	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
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	kfree_skb(skb);
	return -EHOSTUNREACH;
}
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EXPORT_SYMBOL(ip_queue_xmit);
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static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
{
	to->pkt_type = from->pkt_type;
	to->priority = from->priority;
	to->protocol = from->protocol;
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	skb_dst_drop(to);
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	skb_dst_copy(to, from);
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	to->dev = from->dev;
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	to->mark = from->mark;
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	/* Copy the flags to each fragment. */
	IPCB(to)->flags = IPCB(from)->flags;

#ifdef CONFIG_NET_SCHED
	to->tc_index = from->tc_index;
#endif
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	nf_copy(to, from);
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#if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
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	to->nf_trace = from->nf_trace;
#endif
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#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
	to->ipvs_property = from->ipvs_property;
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#endif
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	skb_copy_secmark(to, from);
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}

/*
 *	This IP datagram is too large to be sent in one piece.  Break it up into
 *	smaller pieces (each of size equal to IP header plus
 *	a block of the data of the original IP data part) that will yet fit in a
 *	single device frame, and queue such a frame for sending.
 */

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int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
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{
	struct iphdr *iph;
	int ptr;
	struct net_device *dev;
	struct sk_buff *skb2;
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	unsigned int mtu, hlen, left, len, ll_rs;
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	int offset;
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	__be16 not_last_frag;
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	struct rtable *rt = skb_rtable(skb);
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	int err = 0;

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	dev = rt->dst.dev;
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	/*
	 *	Point into the IP datagram header.
	 */

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	iph = ip_hdr(skb);
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	if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
		     (IPCB(skb)->frag_max_size &&
		      IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) {
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		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
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		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
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			  htonl(ip_skb_dst_mtu(skb)));
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		kfree_skb(skb);
		return -EMSGSIZE;
	}

	/*
	 *	Setup starting values.
	 */

	hlen = iph->ihl * 4;
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	mtu = dst_mtu(&rt->dst) - hlen;	/* Size of data space */
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#ifdef CONFIG_BRIDGE_NETFILTER
	if (skb->nf_bridge)
		mtu -= nf_bridge_mtu_reduction(skb);
#endif
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	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
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	/* When frag_list is given, use it. First, check its validity:
	 * some transformers could create wrong frag_list or break existing
	 * one, it is not prohibited. In this case fall back to copying.
	 *
	 * LATER: this step can be merged to real generation of fragments,
	 * we can switch to copy when see the first bad fragment.
	 */
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	if (skb_has_frag_list(skb)) {
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		struct sk_buff *frag, *frag2;
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		int first_len = skb_pagelen(skb);

		if (first_len - hlen > mtu ||
		    ((first_len - hlen) & 7) ||
496
		    ip_is_fragment(iph) ||
L
Linus Torvalds 已提交
497 498 499
		    skb_cloned(skb))
			goto slow_path;

500
		skb_walk_frags(skb, frag) {
L
Linus Torvalds 已提交
501 502 503 504
			/* Correct geometry. */
			if (frag->len > mtu ||
			    ((frag->len & 7) && frag->next) ||
			    skb_headroom(frag) < hlen)
505
				goto slow_path_clean;
L
Linus Torvalds 已提交
506 507 508

			/* Partially cloned skb? */
			if (skb_shared(frag))
509
				goto slow_path_clean;
510 511 512 513 514 515

			BUG_ON(frag->sk);
			if (skb->sk) {
				frag->sk = skb->sk;
				frag->destructor = sock_wfree;
			}
516
			skb->truesize -= frag->truesize;
L
Linus Torvalds 已提交
517 518 519 520 521 522 523
		}

		/* Everything is OK. Generate! */

		err = 0;
		offset = 0;
		frag = skb_shinfo(skb)->frag_list;
524
		skb_frag_list_init(skb);
L
Linus Torvalds 已提交
525 526 527 528 529 530 531 532 533 534 535
		skb->data_len = first_len - skb_headlen(skb);
		skb->len = first_len;
		iph->tot_len = htons(first_len);
		iph->frag_off = htons(IP_MF);
		ip_send_check(iph);

		for (;;) {
			/* Prepare header of the next frame,
			 * before previous one went down. */
			if (frag) {
				frag->ip_summed = CHECKSUM_NONE;
536
				skb_reset_transport_header(frag);
537 538
				__skb_push(frag, hlen);
				skb_reset_network_header(frag);
539
				memcpy(skb_network_header(frag), iph, hlen);
540
				iph = ip_hdr(frag);
L
Linus Torvalds 已提交
541 542 543 544 545 546 547 548 549 550 551 552 553 554
				iph->tot_len = htons(frag->len);
				ip_copy_metadata(frag, skb);
				if (offset == 0)
					ip_options_fragment(frag);
				offset += skb->len - hlen;
				iph->frag_off = htons(offset>>3);
				if (frag->next != NULL)
					iph->frag_off |= htons(IP_MF);
				/* Ready, complete checksum */
				ip_send_check(iph);
			}

			err = output(skb);

555
			if (!err)
P
Pavel Emelyanov 已提交
556
				IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
557 558 559 560 561 562 563 564 565
			if (err || !frag)
				break;

			skb = frag;
			frag = skb->next;
			skb->next = NULL;
		}

		if (err == 0) {
P
Pavel Emelyanov 已提交
566
			IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
567 568 569 570 571 572 573 574
			return 0;
		}

		while (frag) {
			skb = frag->next;
			kfree_skb(frag);
			frag = skb;
		}
P
Pavel Emelyanov 已提交
575
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
576
		return err;
577 578 579 580 581 582 583 584 585

slow_path_clean:
		skb_walk_frags(skb, frag2) {
			if (frag2 == frag)
				break;
			frag2->sk = NULL;
			frag2->destructor = NULL;
			skb->truesize += frag2->truesize;
		}
L
Linus Torvalds 已提交
586 587 588
	}

slow_path:
589 590 591
	/* for offloaded checksums cleanup checksum before fragmentation */
	if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
		goto fail;
592
	iph = ip_hdr(skb);
593

L
Linus Torvalds 已提交
594
	left = skb->len - hlen;		/* Space per frame */
595
	ptr = hlen;		/* Where to start from */
L
Linus Torvalds 已提交
596 597

	/* for bridged IP traffic encapsulated inside f.e. a vlan header,
598 599
	 * we need to make room for the encapsulating header
	 */
600
	ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
601

L
Linus Torvalds 已提交
602 603 604 605 606 607 608 609 610 611 612
	/*
	 *	Fragment the datagram.
	 */

	offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
	not_last_frag = iph->frag_off & htons(IP_MF);

	/*
	 *	Keep copying data until we run out.
	 */

S
Stephen Hemminger 已提交
613
	while (left > 0) {
L
Linus Torvalds 已提交
614 615 616 617
		len = left;
		/* IF: it doesn't fit, use 'mtu' - the data space left */
		if (len > mtu)
			len = mtu;
L
Lucas De Marchi 已提交
618
		/* IF: we are not sending up to and including the packet end
L
Linus Torvalds 已提交
619 620 621 622 623 624 625 626 627
		   then align the next start on an eight byte boundary */
		if (len < left)	{
			len &= ~7;
		}
		/*
		 *	Allocate buffer.
		 */

		if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
628
			NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
L
Linus Torvalds 已提交
629 630 631 632 633 634 635 636 637 638 639
			err = -ENOMEM;
			goto fail;
		}

		/*
		 *	Set up data on packet
		 */

		ip_copy_metadata(skb2, skb);
		skb_reserve(skb2, ll_rs);
		skb_put(skb2, len + hlen);
640
		skb_reset_network_header(skb2);
641
		skb2->transport_header = skb2->network_header + hlen;
L
Linus Torvalds 已提交
642 643 644 645 646 647 648 649 650 651 652 653 654

		/*
		 *	Charge the memory for the fragment to any owner
		 *	it might possess
		 */

		if (skb->sk)
			skb_set_owner_w(skb2, skb->sk);

		/*
		 *	Copy the packet header into the new buffer.
		 */

655
		skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
L
Linus Torvalds 已提交
656 657 658 659

		/*
		 *	Copy a block of the IP datagram.
		 */
660
		if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
L
Linus Torvalds 已提交
661 662 663 664 665 666
			BUG();
		left -= len;

		/*
		 *	Fill in the new header fields.
		 */
667
		iph = ip_hdr(skb2);
L
Linus Torvalds 已提交
668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697
		iph->frag_off = htons((offset >> 3));

		/* ANK: dirty, but effective trick. Upgrade options only if
		 * the segment to be fragmented was THE FIRST (otherwise,
		 * options are already fixed) and make it ONCE
		 * on the initial skb, so that all the following fragments
		 * will inherit fixed options.
		 */
		if (offset == 0)
			ip_options_fragment(skb);

		/*
		 *	Added AC : If we are fragmenting a fragment that's not the
		 *		   last fragment then keep MF on each bit
		 */
		if (left > 0 || not_last_frag)
			iph->frag_off |= htons(IP_MF);
		ptr += len;
		offset += len;

		/*
		 *	Put this fragment into the sending queue.
		 */
		iph->tot_len = htons(len + hlen);

		ip_send_check(iph);

		err = output(skb2);
		if (err)
			goto fail;
698

P
Pavel Emelyanov 已提交
699
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
700
	}
701
	consume_skb(skb);
P
Pavel Emelyanov 已提交
702
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
703 704 705
	return err;

fail:
706
	kfree_skb(skb);
P
Pavel Emelyanov 已提交
707
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
708 709
	return err;
}
710 711
EXPORT_SYMBOL(ip_fragment);

L
Linus Torvalds 已提交
712 713 714 715 716
int
ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
	struct iovec *iov = from;

717
	if (skb->ip_summed == CHECKSUM_PARTIAL) {
L
Linus Torvalds 已提交
718 719 720
		if (memcpy_fromiovecend(to, iov, offset, len) < 0)
			return -EFAULT;
	} else {
721
		__wsum csum = 0;
L
Linus Torvalds 已提交
722 723 724 725 726 727
		if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
			return -EFAULT;
		skb->csum = csum_block_add(skb->csum, csum, odd);
	}
	return 0;
}
E
Eric Dumazet 已提交
728
EXPORT_SYMBOL(ip_generic_getfrag);
L
Linus Torvalds 已提交
729

730
static inline __wsum
L
Linus Torvalds 已提交
731 732 733
csum_page(struct page *page, int offset, int copy)
{
	char *kaddr;
734
	__wsum csum;
L
Linus Torvalds 已提交
735 736 737 738 739 740
	kaddr = kmap(page);
	csum = csum_partial(kaddr + offset, copy, 0);
	kunmap(page);
	return csum;
}

A
Adrian Bunk 已提交
741
static inline int ip_ufo_append_data(struct sock *sk,
742
			struct sk_buff_head *queue,
743 744 745
			int getfrag(void *from, char *to, int offset, int len,
			       int odd, struct sk_buff *skb),
			void *from, int length, int hh_len, int fragheaderlen,
746
			int transhdrlen, int maxfraglen, unsigned int flags)
747 748 749 750 751 752 753 754
{
	struct sk_buff *skb;
	int err;

	/* There is support for UDP fragmentation offload by network
	 * device, so create one single skb packet containing complete
	 * udp datagram
	 */
755
	if ((skb = skb_peek_tail(queue)) == NULL) {
756 757 758 759 760 761 762 763 764 765 766
		skb = sock_alloc_send_skb(sk,
			hh_len + fragheaderlen + transhdrlen + 20,
			(flags & MSG_DONTWAIT), &err);

		if (skb == NULL)
			return err;

		/* reserve space for Hardware header */
		skb_reserve(skb, hh_len);

		/* create space for UDP/IP header */
767
		skb_put(skb, fragheaderlen + transhdrlen);
768 769

		/* initialize network header pointer */
770
		skb_reset_network_header(skb);
771 772

		/* initialize protocol header pointer */
773
		skb->transport_header = skb->network_header + fragheaderlen;
774

775
		skb->ip_summed = CHECKSUM_PARTIAL;
776 777
		skb->csum = 0;

778
		/* specify the length of each IP datagram fragment */
779
		skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
H
Herbert Xu 已提交
780
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
781
		__skb_queue_tail(queue, skb);
782
	}
783 784 785

	return skb_append_datato_frags(sk, skb, getfrag, from,
				       (length - transhdrlen));
786 787
}

788 789 790
static int __ip_append_data(struct sock *sk,
			    struct flowi4 *fl4,
			    struct sk_buff_head *queue,
791
			    struct inet_cork *cork,
792
			    struct page_frag *pfrag,
793 794 795 796
			    int getfrag(void *from, char *to, int offset,
					int len, int odd, struct sk_buff *skb),
			    void *from, int length, int transhdrlen,
			    unsigned int flags)
L
Linus Torvalds 已提交
797 798 799 800
{
	struct inet_sock *inet = inet_sk(sk);
	struct sk_buff *skb;

801
	struct ip_options *opt = cork->opt;
L
Linus Torvalds 已提交
802 803 804 805 806 807 808 809
	int hh_len;
	int exthdrlen;
	int mtu;
	int copy;
	int err;
	int offset = 0;
	unsigned int maxfraglen, fragheaderlen;
	int csummode = CHECKSUM_NONE;
810
	struct rtable *rt = (struct rtable *)cork->dst;
L
Linus Torvalds 已提交
811

812 813 814
	skb = skb_peek_tail(queue);

	exthdrlen = !skb ? rt->dst.header_len : 0;
815
	mtu = cork->fragsize;
L
Linus Torvalds 已提交
816

817
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
L
Linus Torvalds 已提交
818 819 820 821

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;

822
	if (cork->length + length > 0xFFFF - fragheaderlen) {
823
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
E
Eric Dumazet 已提交
824
			       mtu-exthdrlen);
L
Linus Torvalds 已提交
825 826 827 828 829 830 831 832 833
		return -EMSGSIZE;
	}

	/*
	 * transhdrlen > 0 means that this is the first fragment and we wish
	 * it won't be fragmented in the future.
	 */
	if (transhdrlen &&
	    length + fragheaderlen <= mtu &&
834
	    rt->dst.dev->features & NETIF_F_V4_CSUM &&
L
Linus Torvalds 已提交
835
	    !exthdrlen)
836
		csummode = CHECKSUM_PARTIAL;
L
Linus Torvalds 已提交
837

838
	cork->length += length;
839
	if (((length > mtu) || (skb && skb_is_gso(skb))) &&
840
	    (sk->sk_protocol == IPPROTO_UDP) &&
841
	    (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
842 843
		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
					 hh_len, fragheaderlen, transhdrlen,
844
					 maxfraglen, flags);
845
		if (err)
846 847 848
			goto error;
		return 0;
	}
L
Linus Torvalds 已提交
849 850 851 852 853 854 855 856

	/* So, what's going on in the loop below?
	 *
	 * We use calculated fragment length to generate chained skb,
	 * each of segments is IP fragment ready for sending to network after
	 * adding appropriate IP header.
	 */

857
	if (!skb)
L
Linus Torvalds 已提交
858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887
		goto alloc_new_skb;

	while (length > 0) {
		/* Check if the remaining data fits into current packet. */
		copy = mtu - skb->len;
		if (copy < length)
			copy = maxfraglen - skb->len;
		if (copy <= 0) {
			char *data;
			unsigned int datalen;
			unsigned int fraglen;
			unsigned int fraggap;
			unsigned int alloclen;
			struct sk_buff *skb_prev;
alloc_new_skb:
			skb_prev = skb;
			if (skb_prev)
				fraggap = skb_prev->len - maxfraglen;
			else
				fraggap = 0;

			/*
			 * If remaining data exceeds the mtu,
			 * we know we need more fragment(s).
			 */
			datalen = length + fraggap;
			if (datalen > mtu - fragheaderlen)
				datalen = maxfraglen - fragheaderlen;
			fraglen = datalen + fragheaderlen;

888
			if ((flags & MSG_MORE) &&
889
			    !(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
890 891
				alloclen = mtu;
			else
892
				alloclen = fraglen;
L
Linus Torvalds 已提交
893

894 895
			alloclen += exthdrlen;

L
Linus Torvalds 已提交
896 897 898 899 900
			/* The last fragment gets additional space at tail.
			 * Note, with MSG_MORE we overallocate on fragments,
			 * because we have no idea what fragment will be
			 * the last.
			 */
901
			if (datalen == length + fraggap)
902
				alloclen += rt->dst.trailer_len;
903

L
Linus Torvalds 已提交
904
			if (transhdrlen) {
905
				skb = sock_alloc_send_skb(sk,
L
Linus Torvalds 已提交
906 907 908 909 910 911
						alloclen + hh_len + 15,
						(flags & MSG_DONTWAIT), &err);
			} else {
				skb = NULL;
				if (atomic_read(&sk->sk_wmem_alloc) <=
				    2 * sk->sk_sndbuf)
912
					skb = sock_wmalloc(sk,
L
Linus Torvalds 已提交
913 914 915 916
							   alloclen + hh_len + 15, 1,
							   sk->sk_allocation);
				if (unlikely(skb == NULL))
					err = -ENOBUFS;
917 918 919
				else
					/* only the initial fragment is
					   time stamped */
920
					cork->tx_flags = 0;
L
Linus Torvalds 已提交
921 922 923 924 925 926 927 928 929 930
			}
			if (skb == NULL)
				goto error;

			/*
			 *	Fill in the control structures
			 */
			skb->ip_summed = csummode;
			skb->csum = 0;
			skb_reserve(skb, hh_len);
931
			skb_shinfo(skb)->tx_flags = cork->tx_flags;
L
Linus Torvalds 已提交
932 933 934 935

			/*
			 *	Find where to start putting bytes.
			 */
936
			data = skb_put(skb, fraglen + exthdrlen);
937
			skb_set_network_header(skb, exthdrlen);
938 939
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
940
			data += fragheaderlen + exthdrlen;
L
Linus Torvalds 已提交
941 942 943 944 945 946 947 948

			if (fraggap) {
				skb->csum = skb_copy_and_csum_bits(
					skb_prev, maxfraglen,
					data + transhdrlen, fraggap, 0);
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
				data += fraggap;
949
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967
			}

			copy = datalen - transhdrlen - fraggap;
			if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
				err = -EFAULT;
				kfree_skb(skb);
				goto error;
			}

			offset += copy;
			length -= datalen - fraggap;
			transhdrlen = 0;
			exthdrlen = 0;
			csummode = CHECKSUM_NONE;

			/*
			 * Put the packet on the pending queue.
			 */
968
			__skb_queue_tail(queue, skb);
L
Linus Torvalds 已提交
969 970 971 972 973 974
			continue;
		}

		if (copy > length)
			copy = length;

975
		if (!(rt->dst.dev->features&NETIF_F_SG)) {
L
Linus Torvalds 已提交
976 977 978
			unsigned int off;

			off = skb->len;
979
			if (getfrag(from, skb_put(skb, copy),
L
Linus Torvalds 已提交
980 981 982 983 984 985 986 987
					offset, copy, off, skb) < 0) {
				__skb_trim(skb, off);
				err = -EFAULT;
				goto error;
			}
		} else {
			int i = skb_shinfo(skb)->nr_frags;

988 989
			err = -ENOMEM;
			if (!sk_page_frag_refill(sk, pfrag))
L
Linus Torvalds 已提交
990
				goto error;
991 992 993 994 995 996 997 998 999 1000 1001

			if (!skb_can_coalesce(skb, i, pfrag->page,
					      pfrag->offset)) {
				err = -EMSGSIZE;
				if (i == MAX_SKB_FRAGS)
					goto error;

				__skb_fill_page_desc(skb, i, pfrag->page,
						     pfrag->offset, 0);
				skb_shinfo(skb)->nr_frags = ++i;
				get_page(pfrag->page);
L
Linus Torvalds 已提交
1002
			}
1003 1004 1005 1006 1007 1008 1009 1010
			copy = min_t(int, copy, pfrag->size - pfrag->offset);
			if (getfrag(from,
				    page_address(pfrag->page) + pfrag->offset,
				    offset, copy, skb->len, skb) < 0)
				goto error_efault;

			pfrag->offset += copy;
			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
L
Linus Torvalds 已提交
1011 1012
			skb->len += copy;
			skb->data_len += copy;
1013 1014
			skb->truesize += copy;
			atomic_add(copy, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1015 1016 1017 1018 1019 1020 1021
		}
		offset += copy;
		length -= copy;
	}

	return 0;

1022 1023
error_efault:
	err = -EFAULT;
L
Linus Torvalds 已提交
1024
error:
1025
	cork->length -= length;
P
Pavel Emelyanov 已提交
1026
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1027
	return err;
L
Linus Torvalds 已提交
1028 1029
}

1030 1031 1032 1033
static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
			 struct ipcm_cookie *ipc, struct rtable **rtp)
{
	struct inet_sock *inet = inet_sk(sk);
1034
	struct ip_options_rcu *opt;
1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047
	struct rtable *rt;

	/*
	 * setup for corking.
	 */
	opt = ipc->opt;
	if (opt) {
		if (cork->opt == NULL) {
			cork->opt = kmalloc(sizeof(struct ip_options) + 40,
					    sk->sk_allocation);
			if (unlikely(cork->opt == NULL))
				return -ENOBUFS;
		}
1048
		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059
		cork->flags |= IPCORK_OPT;
		cork->addr = ipc->addr;
	}
	rt = *rtp;
	if (unlikely(!rt))
		return -EFAULT;
	/*
	 * We steal reference to this route, caller should not release it
	 */
	*rtp = NULL;
	cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1060
			 rt->dst.dev->mtu : dst_mtu(&rt->dst);
1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078
	cork->dst = &rt->dst;
	cork->length = 0;
	cork->tx_flags = ipc->tx_flags;

	return 0;
}

/*
 *	ip_append_data() and ip_append_page() can make one large IP datagram
 *	from many pieces of data. Each pieces will be holded on the socket
 *	until ip_push_pending_frames() is called. Each piece can be a page
 *	or non-page data.
 *
 *	Not only UDP, other transport protocols - e.g. raw sockets - can use
 *	this interface potentially.
 *
 *	LATER: length must be adjusted by pad at tail, when it is required.
 */
1079
int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092
		   int getfrag(void *from, char *to, int offset, int len,
			       int odd, struct sk_buff *skb),
		   void *from, int length, int transhdrlen,
		   struct ipcm_cookie *ipc, struct rtable **rtp,
		   unsigned int flags)
{
	struct inet_sock *inet = inet_sk(sk);
	int err;

	if (flags&MSG_PROBE)
		return 0;

	if (skb_queue_empty(&sk->sk_write_queue)) {
1093
		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1094 1095 1096 1097 1098 1099
		if (err)
			return err;
	} else {
		transhdrlen = 0;
	}

1100 1101
	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
				sk_page_frag(sk), getfrag,
1102 1103 1104
				from, length, transhdrlen, flags);
}

1105
ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
L
Linus Torvalds 已提交
1106 1107 1108 1109 1110 1111
		       int offset, size_t size, int flags)
{
	struct inet_sock *inet = inet_sk(sk);
	struct sk_buff *skb;
	struct rtable *rt;
	struct ip_options *opt = NULL;
1112
	struct inet_cork *cork;
L
Linus Torvalds 已提交
1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127
	int hh_len;
	int mtu;
	int len;
	int err;
	unsigned int maxfraglen, fragheaderlen, fraggap;

	if (inet->hdrincl)
		return -EPERM;

	if (flags&MSG_PROBE)
		return 0;

	if (skb_queue_empty(&sk->sk_write_queue))
		return -EINVAL;

1128 1129 1130 1131
	cork = &inet->cork.base;
	rt = (struct rtable *)cork->dst;
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1132

1133
	if (!(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
1134 1135
		return -EOPNOTSUPP;

1136
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1137
	mtu = cork->fragsize;
L
Linus Torvalds 已提交
1138 1139 1140 1141

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;

1142
	if (cork->length + size > 0xFFFF - fragheaderlen) {
1143
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
L
Linus Torvalds 已提交
1144 1145 1146 1147 1148 1149
		return -EMSGSIZE;
	}

	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
		return -EINVAL;

1150
	cork->length += size;
1151 1152
	if ((size + skb->len > mtu) &&
	    (sk->sk_protocol == IPPROTO_UDP) &&
1153
	    (rt->dst.dev->features & NETIF_F_UFO)) {
1154
		skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
H
Herbert Xu 已提交
1155
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1156
	}
1157

L
Linus Torvalds 已提交
1158 1159 1160 1161

	while (size > 0) {
		int i;

H
Herbert Xu 已提交
1162
		if (skb_is_gso(skb))
1163 1164 1165 1166 1167 1168 1169 1170
			len = size;
		else {

			/* Check if the remaining data fits into current packet. */
			len = mtu - skb->len;
			if (len < size)
				len = maxfraglen - skb->len;
		}
L
Linus Torvalds 已提交
1171 1172 1173 1174 1175
		if (len <= 0) {
			struct sk_buff *skb_prev;
			int alloclen;

			skb_prev = skb;
1176
			fraggap = skb_prev->len - maxfraglen;
L
Linus Torvalds 已提交
1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194

			alloclen = fragheaderlen + hh_len + fraggap + 15;
			skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
			if (unlikely(!skb)) {
				err = -ENOBUFS;
				goto error;
			}

			/*
			 *	Fill in the control structures
			 */
			skb->ip_summed = CHECKSUM_NONE;
			skb->csum = 0;
			skb_reserve(skb, hh_len);

			/*
			 *	Find where to start putting bytes.
			 */
1195
			skb_put(skb, fragheaderlen + fraggap);
1196
			skb_reset_network_header(skb);
1197 1198
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
L
Linus Torvalds 已提交
1199
			if (fraggap) {
1200 1201
				skb->csum = skb_copy_and_csum_bits(skb_prev,
								   maxfraglen,
1202
						    skb_transport_header(skb),
1203
								   fraggap, 0);
L
Linus Torvalds 已提交
1204 1205
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
1206
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219
			}

			/*
			 * Put the packet on the pending queue.
			 */
			__skb_queue_tail(&sk->sk_write_queue, skb);
			continue;
		}

		i = skb_shinfo(skb)->nr_frags;
		if (len > size)
			len = size;
		if (skb_can_coalesce(skb, i, page, offset)) {
E
Eric Dumazet 已提交
1220
			skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
L
Linus Torvalds 已提交
1221 1222 1223 1224 1225 1226 1227 1228 1229
		} else if (i < MAX_SKB_FRAGS) {
			get_page(page);
			skb_fill_page_desc(skb, i, page, offset, len);
		} else {
			err = -EMSGSIZE;
			goto error;
		}

		if (skb->ip_summed == CHECKSUM_NONE) {
1230
			__wsum csum;
L
Linus Torvalds 已提交
1231 1232 1233 1234 1235 1236
			csum = csum_page(page, offset, len);
			skb->csum = csum_block_add(skb->csum, csum, skb->len);
		}

		skb->len += len;
		skb->data_len += len;
1237 1238
		skb->truesize += len;
		atomic_add(len, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1239 1240 1241 1242 1243 1244
		offset += len;
		size -= len;
	}
	return 0;

error:
1245
	cork->length -= size;
P
Pavel Emelyanov 已提交
1246
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1247 1248 1249
	return err;
}

1250
static void ip_cork_release(struct inet_cork *cork)
1251
{
1252 1253 1254 1255 1256
	cork->flags &= ~IPCORK_OPT;
	kfree(cork->opt);
	cork->opt = NULL;
	dst_release(cork->dst);
	cork->dst = NULL;
1257 1258
}

L
Linus Torvalds 已提交
1259 1260 1261 1262
/*
 *	Combined all pending IP fragments on the socket as one IP datagram
 *	and push them out.
 */
1263
struct sk_buff *__ip_make_skb(struct sock *sk,
1264
			      struct flowi4 *fl4,
1265 1266
			      struct sk_buff_head *queue,
			      struct inet_cork *cork)
L
Linus Torvalds 已提交
1267 1268 1269 1270
{
	struct sk_buff *skb, *tmp_skb;
	struct sk_buff **tail_skb;
	struct inet_sock *inet = inet_sk(sk);
1271
	struct net *net = sock_net(sk);
L
Linus Torvalds 已提交
1272
	struct ip_options *opt = NULL;
1273
	struct rtable *rt = (struct rtable *)cork->dst;
L
Linus Torvalds 已提交
1274
	struct iphdr *iph;
1275
	__be16 df = 0;
L
Linus Torvalds 已提交
1276 1277
	__u8 ttl;

1278
	if ((skb = __skb_dequeue(queue)) == NULL)
L
Linus Torvalds 已提交
1279 1280 1281 1282
		goto out;
	tail_skb = &(skb_shinfo(skb)->frag_list);

	/* move skb->data to ip header from ext header */
1283
	if (skb->data < skb_network_header(skb))
1284
		__skb_pull(skb, skb_network_offset(skb));
1285
	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1286
		__skb_pull(tmp_skb, skb_network_header_len(skb));
L
Linus Torvalds 已提交
1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299
		*tail_skb = tmp_skb;
		tail_skb = &(tmp_skb->next);
		skb->len += tmp_skb->len;
		skb->data_len += tmp_skb->len;
		skb->truesize += tmp_skb->truesize;
		tmp_skb->destructor = NULL;
		tmp_skb->sk = NULL;
	}

	/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
	 * to fragment the frame generated here. No matter, what transforms
	 * how transforms change size of the packet, it will come out.
	 */
J
John Heffner 已提交
1300
	if (inet->pmtudisc < IP_PMTUDISC_DO)
L
Linus Torvalds 已提交
1301 1302 1303 1304 1305
		skb->local_df = 1;

	/* DF bit is set when we want to see DF on outgoing frames.
	 * If local_df is set too, we still allow to fragment this frame
	 * locally. */
J
John Heffner 已提交
1306
	if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1307 1308
	    (skb->len <= dst_mtu(&rt->dst) &&
	     ip_dont_fragment(sk, &rt->dst)))
L
Linus Torvalds 已提交
1309 1310
		df = htons(IP_DF);

1311 1312
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1313 1314 1315 1316

	if (rt->rt_type == RTN_MULTICAST)
		ttl = inet->mc_ttl;
	else
1317
		ttl = ip_select_ttl(inet, &rt->dst);
L
Linus Torvalds 已提交
1318

1319
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
1320 1321 1322 1323 1324 1325
	iph->version = 4;
	iph->ihl = 5;
	iph->tos = inet->tos;
	iph->frag_off = df;
	iph->ttl = ttl;
	iph->protocol = sk->sk_protocol;
1326
	ip_copy_addrs(iph, fl4);
1327
	ip_select_ident(iph, &rt->dst, sk);
L
Linus Torvalds 已提交
1328

1329 1330 1331 1332 1333
	if (opt) {
		iph->ihl += opt->optlen>>2;
		ip_options_build(skb, opt, cork->addr, rt, 0);
	}

L
Linus Torvalds 已提交
1334
	skb->priority = sk->sk_priority;
1335
	skb->mark = sk->sk_mark;
1336 1337 1338 1339
	/*
	 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
	 * on dst refcount
	 */
1340
	cork->dst = NULL;
1341
	skb_dst_set(skb, &rt->dst);
L
Linus Torvalds 已提交
1342

1343
	if (iph->protocol == IPPROTO_ICMP)
1344
		icmp_out_count(net, ((struct icmphdr *)
1345 1346
			skb_transport_header(skb))->type);

1347 1348 1349 1350 1351
	ip_cork_release(cork);
out:
	return skb;
}

E
Eric Dumazet 已提交
1352
int ip_send_skb(struct net *net, struct sk_buff *skb)
1353 1354 1355
{
	int err;

H
Herbert Xu 已提交
1356
	err = ip_local_out(skb);
L
Linus Torvalds 已提交
1357 1358
	if (err) {
		if (err > 0)
E
Eric Dumazet 已提交
1359
			err = net_xmit_errno(err);
L
Linus Torvalds 已提交
1360
		if (err)
1361
			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1362 1363 1364 1365 1366
	}

	return err;
}

1367
int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1368
{
1369 1370
	struct sk_buff *skb;

1371
	skb = ip_finish_skb(sk, fl4);
1372 1373 1374 1375
	if (!skb)
		return 0;

	/* Netfilter gets whole the not fragmented skb. */
E
Eric Dumazet 已提交
1376
	return ip_send_skb(sock_net(sk), skb);
1377 1378
}

L
Linus Torvalds 已提交
1379 1380 1381
/*
 *	Throw away all pending data on the socket.
 */
1382 1383 1384
static void __ip_flush_pending_frames(struct sock *sk,
				      struct sk_buff_head *queue,
				      struct inet_cork *cork)
L
Linus Torvalds 已提交
1385 1386 1387
{
	struct sk_buff *skb;

1388
	while ((skb = __skb_dequeue_tail(queue)) != NULL)
L
Linus Torvalds 已提交
1389 1390
		kfree_skb(skb);

1391 1392 1393 1394 1395
	ip_cork_release(cork);
}

void ip_flush_pending_frames(struct sock *sk)
{
1396
	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
L
Linus Torvalds 已提交
1397 1398
}

1399
struct sk_buff *ip_make_skb(struct sock *sk,
1400
			    struct flowi4 *fl4,
1401 1402 1403 1404 1405 1406
			    int getfrag(void *from, char *to, int offset,
					int len, int odd, struct sk_buff *skb),
			    void *from, int length, int transhdrlen,
			    struct ipcm_cookie *ipc, struct rtable **rtp,
			    unsigned int flags)
{
1407
	struct inet_cork cork;
1408 1409 1410 1411 1412 1413 1414 1415
	struct sk_buff_head queue;
	int err;

	if (flags & MSG_PROBE)
		return NULL;

	__skb_queue_head_init(&queue);

1416 1417
	cork.flags = 0;
	cork.addr = 0;
1418
	cork.opt = NULL;
1419 1420 1421 1422
	err = ip_setup_cork(sk, &cork, ipc, rtp);
	if (err)
		return ERR_PTR(err);

1423 1424
	err = __ip_append_data(sk, fl4, &queue, &cork,
			       &current->task_frag, getfrag,
1425 1426 1427 1428 1429 1430
			       from, length, transhdrlen, flags);
	if (err) {
		__ip_flush_pending_frames(sk, &queue, &cork);
		return ERR_PTR(err);
	}

1431
	return __ip_make_skb(sk, fl4, &queue, &cork);
1432
}
L
Linus Torvalds 已提交
1433 1434 1435 1436

/*
 *	Fetch data from kernel space and fill in checksum if needed.
 */
1437
static int ip_reply_glue_bits(void *dptr, char *to, int offset,
L
Linus Torvalds 已提交
1438 1439
			      int len, int odd, struct sk_buff *skb)
{
1440
	__wsum csum;
L
Linus Torvalds 已提交
1441 1442 1443

	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
	skb->csum = csum_block_add(skb->csum, csum, odd);
1444
	return 0;
L
Linus Torvalds 已提交
1445 1446
}

1447
/*
L
Linus Torvalds 已提交
1448
 *	Generic function to send a packet as reply to another packet.
1449
 *	Used to send some TCP resets/acks so far.
L
Linus Torvalds 已提交
1450
 *
1451
 *	Use a fake percpu inet socket to avoid false sharing and contention.
L
Linus Torvalds 已提交
1452
 */
1453 1454 1455 1456 1457 1458 1459 1460 1461
static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
	.sk = {
		.__sk_common = {
			.skc_refcnt = ATOMIC_INIT(1),
		},
		.sk_wmem_alloc	= ATOMIC_INIT(1),
		.sk_allocation	= GFP_ATOMIC,
		.sk_flags	= (1UL << SOCK_USE_WRITE_QUEUE),
	},
1462 1463
	.pmtudisc	= IP_PMTUDISC_WANT,
	.uc_ttl		= -1,
1464 1465 1466
};

void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
1467 1468
			   __be32 saddr, const struct ip_reply_arg *arg,
			   unsigned int len)
L
Linus Torvalds 已提交
1469
{
1470
	struct ip_options_data replyopts;
L
Linus Torvalds 已提交
1471
	struct ipcm_cookie ipc;
1472
	struct flowi4 fl4;
E
Eric Dumazet 已提交
1473
	struct rtable *rt = skb_rtable(skb);
1474 1475 1476
	struct sk_buff *nskb;
	struct sock *sk;
	struct inet_sock *inet;
L
Linus Torvalds 已提交
1477

1478
	if (ip_options_echo(&replyopts.opt.opt, skb))
L
Linus Torvalds 已提交
1479 1480
		return;

1481
	ipc.addr = daddr;
L
Linus Torvalds 已提交
1482
	ipc.opt = NULL;
1483
	ipc.tx_flags = 0;
L
Linus Torvalds 已提交
1484

1485
	if (replyopts.opt.opt.optlen) {
L
Linus Torvalds 已提交
1486 1487
		ipc.opt = &replyopts.opt;

1488 1489
		if (replyopts.opt.opt.srr)
			daddr = replyopts.opt.opt.faddr;
L
Linus Torvalds 已提交
1490 1491
	}

1492
	flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1493
			   RT_TOS(arg->tos),
1494
			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1495
			   ip_reply_arg_flowi_flags(arg),
1496
			   daddr, saddr,
1497 1498
			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1499
	rt = ip_route_output_key(net, &fl4);
1500 1501
	if (IS_ERR(rt))
		return;
L
Linus Torvalds 已提交
1502

1503
	inet = &get_cpu_var(unicast_sock);
L
Linus Torvalds 已提交
1504

1505
	inet->tos = arg->tos;
1506
	sk = &inet->sk;
L
Linus Torvalds 已提交
1507
	sk->sk_priority = skb->priority;
1508
	sk->sk_protocol = ip_hdr(skb)->protocol;
1509
	sk->sk_bound_dev_if = arg->bound_dev_if;
1510 1511 1512
	sock_net_set(sk, net);
	__skb_queue_head_init(&sk->sk_write_queue);
	sk->sk_sndbuf = sysctl_wmem_default;
1513
	ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1514
		       &ipc, &rt, MSG_DONTWAIT);
1515 1516
	nskb = skb_peek(&sk->sk_write_queue);
	if (nskb) {
L
Linus Torvalds 已提交
1517
		if (arg->csumoffset >= 0)
1518 1519
			*((__sum16 *)skb_transport_header(nskb) +
			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1520
								arg->csum));
1521
		nskb->ip_summed = CHECKSUM_NONE;
1522
		skb_orphan(nskb);
1523
		skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1524
		ip_push_pending_frames(sk, &fl4);
L
Linus Torvalds 已提交
1525 1526
	}

1527
	put_cpu_var(unicast_sock);
L
Linus Torvalds 已提交
1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540

	ip_rt_put(rt);
}

void __init ip_init(void)
{
	ip_rt_init();
	inet_initpeers();

#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
	igmp_mc_proc_init();
#endif
}