ip_output.c 38.8 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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}

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int ip_local_out_sk(struct sock *sk, struct sk_buff *skb)
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{
	int err;

	err = __ip_local_out(skb);
	if (likely(err == 1))
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		err = dst_output_sk(sk, skb);
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	return err;
}
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EXPORT_SYMBOL_GPL(ip_local_out_sk);
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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(skb, 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_gso(struct sk_buff *skb)
{
	netdev_features_t features;
	struct sk_buff *segs;
	int ret = 0;

	/* common case: locally created skb or seglen is <= mtu */
	if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||
	      skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb))
		return ip_finish_output2(skb);

	/* Slowpath -  GSO segment length is exceeding the dst MTU.
	 *
	 * This can happen in two cases:
	 * 1) TCP GRO packet, DF bit not set
	 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly
	 * from host network stack.
	 */
	features = netif_skb_features(skb);
	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
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	if (IS_ERR_OR_NULL(segs)) {
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		kfree_skb(skb);
		return -ENOMEM;
	}

	consume_skb(skb);

	do {
		struct sk_buff *nskb = segs->next;
		int err;

		segs->next = NULL;
		err = ip_fragment(segs, ip_finish_output2);

		if (err && ret == 0)
			ret = err;
		segs = nskb;
	} while (segs);

	return ret;
}

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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_is_gso(skb))
		return ip_finish_output_gso(skb);

	if (skb->len > ip_skb_dst_mtu(skb))
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		return ip_fragment(skb, ip_finish_output2);
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	return ip_finish_output2(skb);
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}

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int ip_mc_output(struct sock *sk, struct sk_buff *skb)
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{
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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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}

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int ip_output(struct sock *sk, struct sk_buff *skb)
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{
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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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/* Note: skb->sk can be different from sk, in case of tunnels */
int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
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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->ignore_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_segs(skb, sk, skb_shinfo(skb)->gso_segs ?: 1);
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	/* TODO : should we use skb->sk here instead of sk ? */
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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 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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	mtu = ip_skb_dst_mtu(skb);
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WANG Cong 已提交
503
	if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
504
		     (IPCB(skb)->frag_max_size &&
505
		      IPCB(skb)->frag_max_size > mtu))) {
P
Pavel Emelyanov 已提交
506
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
507
		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
508
			  htonl(mtu));
L
Linus Torvalds 已提交
509 510 511 512 513 514 515 516 517
		kfree_skb(skb);
		return -EMSGSIZE;
	}

	/*
	 *	Setup starting values.
	 */

	hlen = iph->ihl * 4;
518
	mtu = mtu - hlen;	/* Size of data space */
519
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
520 521 522
	if (skb->nf_bridge)
		mtu -= nf_bridge_mtu_reduction(skb);
#endif
H
Herbert Xu 已提交
523
	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
L
Linus Torvalds 已提交
524 525 526 527 528 529 530 531

	/* 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.
	 */
532
	if (skb_has_frag_list(skb)) {
533
		struct sk_buff *frag, *frag2;
L
Linus Torvalds 已提交
534 535 536 537
		int first_len = skb_pagelen(skb);

		if (first_len - hlen > mtu ||
		    ((first_len - hlen) & 7) ||
538
		    ip_is_fragment(iph) ||
L
Linus Torvalds 已提交
539 540 541
		    skb_cloned(skb))
			goto slow_path;

542
		skb_walk_frags(skb, frag) {
L
Linus Torvalds 已提交
543 544 545 546
			/* Correct geometry. */
			if (frag->len > mtu ||
			    ((frag->len & 7) && frag->next) ||
			    skb_headroom(frag) < hlen)
547
				goto slow_path_clean;
L
Linus Torvalds 已提交
548 549 550

			/* Partially cloned skb? */
			if (skb_shared(frag))
551
				goto slow_path_clean;
552 553 554 555 556 557

			BUG_ON(frag->sk);
			if (skb->sk) {
				frag->sk = skb->sk;
				frag->destructor = sock_wfree;
			}
558
			skb->truesize -= frag->truesize;
L
Linus Torvalds 已提交
559 560 561 562 563 564 565
		}

		/* Everything is OK. Generate! */

		err = 0;
		offset = 0;
		frag = skb_shinfo(skb)->frag_list;
566
		skb_frag_list_init(skb);
L
Linus Torvalds 已提交
567 568 569 570 571 572 573 574 575 576 577
		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;
578
				skb_reset_transport_header(frag);
579 580
				__skb_push(frag, hlen);
				skb_reset_network_header(frag);
581
				memcpy(skb_network_header(frag), iph, hlen);
582
				iph = ip_hdr(frag);
L
Linus Torvalds 已提交
583 584 585 586 587 588 589 590 591 592 593 594 595 596
				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);

597
			if (!err)
P
Pavel Emelyanov 已提交
598
				IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
599 600 601 602 603 604 605 606 607
			if (err || !frag)
				break;

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

		if (err == 0) {
P
Pavel Emelyanov 已提交
608
			IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
609 610 611 612 613 614 615 616
			return 0;
		}

		while (frag) {
			skb = frag->next;
			kfree_skb(frag);
			frag = skb;
		}
P
Pavel Emelyanov 已提交
617
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
618
		return err;
619 620 621 622 623 624 625 626 627

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
628 629 630
	}

slow_path:
631 632 633
	/* for offloaded checksums cleanup checksum before fragmentation */
	if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
		goto fail;
634
	iph = ip_hdr(skb);
635

L
Linus Torvalds 已提交
636
	left = skb->len - hlen;		/* Space per frame */
637
	ptr = hlen;		/* Where to start from */
L
Linus Torvalds 已提交
638 639

	/* for bridged IP traffic encapsulated inside f.e. a vlan header,
640 641
	 * we need to make room for the encapsulating header
	 */
642
	ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
643

L
Linus Torvalds 已提交
644 645 646 647 648 649 650 651 652 653 654
	/*
	 *	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
655
	while (left > 0) {
L
Linus Torvalds 已提交
656 657 658 659
		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
660
		/* IF: we are not sending up to and including the packet end
L
Linus Torvalds 已提交
661 662 663 664 665
		   then align the next start on an eight byte boundary */
		if (len < left)	{
			len &= ~7;
		}

666 667 668
		/* Allocate buffer */
		skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
		if (!skb2) {
L
Linus Torvalds 已提交
669 670 671 672 673 674 675 676 677 678 679
			err = -ENOMEM;
			goto fail;
		}

		/*
		 *	Set up data on packet
		 */

		ip_copy_metadata(skb2, skb);
		skb_reserve(skb2, ll_rs);
		skb_put(skb2, len + hlen);
680
		skb_reset_network_header(skb2);
681
		skb2->transport_header = skb2->network_header + hlen;
L
Linus Torvalds 已提交
682 683 684 685 686 687 688 689 690 691 692 693 694

		/*
		 *	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.
		 */

695
		skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
L
Linus Torvalds 已提交
696 697 698 699

		/*
		 *	Copy a block of the IP datagram.
		 */
700
		if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
L
Linus Torvalds 已提交
701 702 703 704 705 706
			BUG();
		left -= len;

		/*
		 *	Fill in the new header fields.
		 */
707
		iph = ip_hdr(skb2);
L
Linus Torvalds 已提交
708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737
		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;
738

P
Pavel Emelyanov 已提交
739
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
740
	}
741
	consume_skb(skb);
P
Pavel Emelyanov 已提交
742
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
743 744 745
	return err;

fail:
746
	kfree_skb(skb);
P
Pavel Emelyanov 已提交
747
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
748 749
	return err;
}
750 751
EXPORT_SYMBOL(ip_fragment);

L
Linus Torvalds 已提交
752 753 754
int
ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
755
	struct msghdr *msg = from;
L
Linus Torvalds 已提交
756

757
	if (skb->ip_summed == CHECKSUM_PARTIAL) {
758
		if (copy_from_iter(to, len, &msg->msg_iter) != len)
L
Linus Torvalds 已提交
759 760
			return -EFAULT;
	} else {
761
		__wsum csum = 0;
762
		if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len)
L
Linus Torvalds 已提交
763 764 765 766 767
			return -EFAULT;
		skb->csum = csum_block_add(skb->csum, csum, odd);
	}
	return 0;
}
E
Eric Dumazet 已提交
768
EXPORT_SYMBOL(ip_generic_getfrag);
L
Linus Torvalds 已提交
769

770
static inline __wsum
L
Linus Torvalds 已提交
771 772 773
csum_page(struct page *page, int offset, int copy)
{
	char *kaddr;
774
	__wsum csum;
L
Linus Torvalds 已提交
775 776 777 778 779 780
	kaddr = kmap(page);
	csum = csum_partial(kaddr + offset, copy, 0);
	kunmap(page);
	return csum;
}

A
Adrian Bunk 已提交
781
static inline int ip_ufo_append_data(struct sock *sk,
782
			struct sk_buff_head *queue,
783 784 785
			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,
786
			int transhdrlen, int maxfraglen, unsigned int flags)
787 788 789 790 791 792 793 794
{
	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
	 */
795
	if ((skb = skb_peek_tail(queue)) == NULL) {
796 797 798 799 800 801 802 803 804 805 806
		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 */
807
		skb_put(skb, fragheaderlen + transhdrlen);
808 809

		/* initialize network header pointer */
810
		skb_reset_network_header(skb);
811 812

		/* initialize protocol header pointer */
813
		skb->transport_header = skb->network_header + fragheaderlen;
814 815 816

		skb->csum = 0;

817

818
		__skb_queue_tail(queue, skb);
819 820
	} else if (skb_is_gso(skb)) {
		goto append;
821
	}
822

823 824 825 826 827 828
	skb->ip_summed = CHECKSUM_PARTIAL;
	/* specify the length of each IP datagram fragment */
	skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
	skb_shinfo(skb)->gso_type = SKB_GSO_UDP;

append:
829 830
	return skb_append_datato_frags(sk, skb, getfrag, from,
				       (length - transhdrlen));
831 832
}

833 834 835
static int __ip_append_data(struct sock *sk,
			    struct flowi4 *fl4,
			    struct sk_buff_head *queue,
836
			    struct inet_cork *cork,
837
			    struct page_frag *pfrag,
838 839 840 841
			    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
842 843 844 845
{
	struct inet_sock *inet = inet_sk(sk);
	struct sk_buff *skb;

846
	struct ip_options *opt = cork->opt;
L
Linus Torvalds 已提交
847 848 849 850 851 852
	int hh_len;
	int exthdrlen;
	int mtu;
	int copy;
	int err;
	int offset = 0;
853
	unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
L
Linus Torvalds 已提交
854
	int csummode = CHECKSUM_NONE;
855
	struct rtable *rt = (struct rtable *)cork->dst;
856
	u32 tskey = 0;
L
Linus Torvalds 已提交
857

858 859 860
	skb = skb_peek_tail(queue);

	exthdrlen = !skb ? rt->dst.header_len : 0;
861
	mtu = cork->fragsize;
862 863 864
	if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
	    sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
		tskey = sk->sk_tskey++;
L
Linus Torvalds 已提交
865

866
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
L
Linus Torvalds 已提交
867 868 869

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
W
WANG Cong 已提交
870
	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
L
Linus Torvalds 已提交
871

872
	if (cork->length + length > maxnonfragsize - fragheaderlen) {
873
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
874
			       mtu - (opt ? opt->optlen : 0));
L
Linus Torvalds 已提交
875 876 877 878 879 880 881 882 883
		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 &&
884
	    rt->dst.dev->features & NETIF_F_V4_CSUM &&
L
Linus Torvalds 已提交
885
	    !exthdrlen)
886
		csummode = CHECKSUM_PARTIAL;
L
Linus Torvalds 已提交
887

888
	cork->length += length;
889
	if (((length > mtu) || (skb && skb_is_gso(skb))) &&
890
	    (sk->sk_protocol == IPPROTO_UDP) &&
891 892
	    (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
	    (sk->sk_type == SOCK_DGRAM)) {
893 894
		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
					 hh_len, fragheaderlen, transhdrlen,
895
					 maxfraglen, flags);
896
		if (err)
897 898 899
			goto error;
		return 0;
	}
L
Linus Torvalds 已提交
900 901 902 903 904 905 906 907

	/* 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.
	 */

908
	if (!skb)
L
Linus Torvalds 已提交
909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938
		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;

939
			if ((flags & MSG_MORE) &&
940
			    !(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
941 942
				alloclen = mtu;
			else
943
				alloclen = fraglen;
L
Linus Torvalds 已提交
944

945 946
			alloclen += exthdrlen;

L
Linus Torvalds 已提交
947 948 949 950 951
			/* 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.
			 */
952
			if (datalen == length + fraggap)
953
				alloclen += rt->dst.trailer_len;
954

L
Linus Torvalds 已提交
955
			if (transhdrlen) {
956
				skb = sock_alloc_send_skb(sk,
L
Linus Torvalds 已提交
957 958 959 960 961 962
						alloclen + hh_len + 15,
						(flags & MSG_DONTWAIT), &err);
			} else {
				skb = NULL;
				if (atomic_read(&sk->sk_wmem_alloc) <=
				    2 * sk->sk_sndbuf)
963
					skb = sock_wmalloc(sk,
L
Linus Torvalds 已提交
964 965 966 967 968 969 970 971 972 973 974 975 976 977
							   alloclen + hh_len + 15, 1,
							   sk->sk_allocation);
				if (unlikely(skb == NULL))
					err = -ENOBUFS;
			}
			if (skb == NULL)
				goto error;

			/*
			 *	Fill in the control structures
			 */
			skb->ip_summed = csummode;
			skb->csum = 0;
			skb_reserve(skb, hh_len);
978 979

			/* only the initial fragment is time stamped */
980
			skb_shinfo(skb)->tx_flags = cork->tx_flags;
981
			cork->tx_flags = 0;
982 983
			skb_shinfo(skb)->tskey = tskey;
			tskey = 0;
L
Linus Torvalds 已提交
984 985 986 987

			/*
			 *	Find where to start putting bytes.
			 */
988
			data = skb_put(skb, fraglen + exthdrlen);
989
			skb_set_network_header(skb, exthdrlen);
990 991
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
992
			data += fragheaderlen + exthdrlen;
L
Linus Torvalds 已提交
993 994 995 996 997 998 999 1000

			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;
1001
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019
			}

			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.
			 */
1020
			__skb_queue_tail(queue, skb);
L
Linus Torvalds 已提交
1021 1022 1023 1024 1025 1026
			continue;
		}

		if (copy > length)
			copy = length;

1027
		if (!(rt->dst.dev->features&NETIF_F_SG)) {
L
Linus Torvalds 已提交
1028 1029 1030
			unsigned int off;

			off = skb->len;
1031
			if (getfrag(from, skb_put(skb, copy),
L
Linus Torvalds 已提交
1032 1033 1034 1035 1036 1037 1038 1039
					offset, copy, off, skb) < 0) {
				__skb_trim(skb, off);
				err = -EFAULT;
				goto error;
			}
		} else {
			int i = skb_shinfo(skb)->nr_frags;

1040 1041
			err = -ENOMEM;
			if (!sk_page_frag_refill(sk, pfrag))
L
Linus Torvalds 已提交
1042
				goto error;
1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053

			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
1054
			}
1055 1056 1057 1058 1059 1060 1061 1062
			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
1063 1064
			skb->len += copy;
			skb->data_len += copy;
1065 1066
			skb->truesize += copy;
			atomic_add(copy, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1067 1068 1069 1070 1071 1072 1073
		}
		offset += copy;
		length -= copy;
	}

	return 0;

1074 1075
error_efault:
	err = -EFAULT;
L
Linus Torvalds 已提交
1076
error:
1077
	cork->length -= length;
P
Pavel Emelyanov 已提交
1078
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1079
	return err;
L
Linus Torvalds 已提交
1080 1081
}

1082 1083 1084
static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
			 struct ipcm_cookie *ipc, struct rtable **rtp)
{
1085
	struct ip_options_rcu *opt;
1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098
	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;
		}
1099
		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109
		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;
1110 1111
	cork->fragsize = ip_sk_use_pmtu(sk) ?
			 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1112 1113
	cork->dst = &rt->dst;
	cork->length = 0;
1114 1115 1116
	cork->ttl = ipc->ttl;
	cork->tos = ipc->tos;
	cork->priority = ipc->priority;
1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132
	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.
 */
1133
int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146
		   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)) {
1147
		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1148 1149 1150 1151 1152 1153
		if (err)
			return err;
	} else {
		transhdrlen = 0;
	}

1154 1155
	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
				sk_page_frag(sk), getfrag,
1156 1157 1158
				from, length, transhdrlen, flags);
}

1159
ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
L
Linus Torvalds 已提交
1160 1161 1162 1163 1164 1165
		       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;
1166
	struct inet_cork *cork;
L
Linus Torvalds 已提交
1167 1168 1169 1170
	int hh_len;
	int mtu;
	int len;
	int err;
1171
	unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
L
Linus Torvalds 已提交
1172 1173 1174 1175 1176 1177 1178 1179 1180 1181

	if (inet->hdrincl)
		return -EPERM;

	if (flags&MSG_PROBE)
		return 0;

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

1182 1183 1184 1185
	cork = &inet->cork.base;
	rt = (struct rtable *)cork->dst;
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1186

1187
	if (!(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
1188 1189
		return -EOPNOTSUPP;

1190
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1191
	mtu = cork->fragsize;
L
Linus Torvalds 已提交
1192 1193 1194

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
W
WANG Cong 已提交
1195
	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
L
Linus Torvalds 已提交
1196

1197
	if (cork->length + size > maxnonfragsize - fragheaderlen) {
1198 1199
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
			       mtu - (opt ? opt->optlen : 0));
L
Linus Torvalds 已提交
1200 1201 1202 1203 1204 1205
		return -EMSGSIZE;
	}

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

1206
	cork->length += size;
1207 1208
	if ((size + skb->len > mtu) &&
	    (sk->sk_protocol == IPPROTO_UDP) &&
1209
	    (rt->dst.dev->features & NETIF_F_UFO)) {
1210
		skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
H
Herbert Xu 已提交
1211
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1212
	}
1213

L
Linus Torvalds 已提交
1214 1215 1216 1217

	while (size > 0) {
		int i;

H
Herbert Xu 已提交
1218
		if (skb_is_gso(skb))
1219 1220 1221 1222 1223 1224 1225 1226
			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
1227 1228 1229 1230 1231
		if (len <= 0) {
			struct sk_buff *skb_prev;
			int alloclen;

			skb_prev = skb;
1232
			fraggap = skb_prev->len - maxfraglen;
L
Linus Torvalds 已提交
1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250

			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.
			 */
1251
			skb_put(skb, fragheaderlen + fraggap);
1252
			skb_reset_network_header(skb);
1253 1254
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
L
Linus Torvalds 已提交
1255
			if (fraggap) {
1256 1257
				skb->csum = skb_copy_and_csum_bits(skb_prev,
								   maxfraglen,
1258
						    skb_transport_header(skb),
1259
								   fraggap, 0);
L
Linus Torvalds 已提交
1260 1261
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
1262
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275
			}

			/*
			 * 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
1276
			skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
L
Linus Torvalds 已提交
1277 1278 1279 1280 1281 1282 1283 1284 1285
		} 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) {
1286
			__wsum csum;
L
Linus Torvalds 已提交
1287 1288 1289 1290 1291 1292
			csum = csum_page(page, offset, len);
			skb->csum = csum_block_add(skb->csum, csum, skb->len);
		}

		skb->len += len;
		skb->data_len += len;
1293 1294
		skb->truesize += len;
		atomic_add(len, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1295 1296 1297 1298 1299 1300
		offset += len;
		size -= len;
	}
	return 0;

error:
1301
	cork->length -= size;
P
Pavel Emelyanov 已提交
1302
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1303 1304 1305
	return err;
}

1306
static void ip_cork_release(struct inet_cork *cork)
1307
{
1308 1309 1310 1311 1312
	cork->flags &= ~IPCORK_OPT;
	kfree(cork->opt);
	cork->opt = NULL;
	dst_release(cork->dst);
	cork->dst = NULL;
1313 1314
}

L
Linus Torvalds 已提交
1315 1316 1317 1318
/*
 *	Combined all pending IP fragments on the socket as one IP datagram
 *	and push them out.
 */
1319
struct sk_buff *__ip_make_skb(struct sock *sk,
1320
			      struct flowi4 *fl4,
1321 1322
			      struct sk_buff_head *queue,
			      struct inet_cork *cork)
L
Linus Torvalds 已提交
1323 1324 1325 1326
{
	struct sk_buff *skb, *tmp_skb;
	struct sk_buff **tail_skb;
	struct inet_sock *inet = inet_sk(sk);
1327
	struct net *net = sock_net(sk);
L
Linus Torvalds 已提交
1328
	struct ip_options *opt = NULL;
1329
	struct rtable *rt = (struct rtable *)cork->dst;
L
Linus Torvalds 已提交
1330
	struct iphdr *iph;
1331
	__be16 df = 0;
L
Linus Torvalds 已提交
1332 1333
	__u8 ttl;

1334
	if ((skb = __skb_dequeue(queue)) == NULL)
L
Linus Torvalds 已提交
1335 1336 1337 1338
		goto out;
	tail_skb = &(skb_shinfo(skb)->frag_list);

	/* move skb->data to ip header from ext header */
1339
	if (skb->data < skb_network_header(skb))
1340
		__skb_pull(skb, skb_network_offset(skb));
1341
	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1342
		__skb_pull(tmp_skb, skb_network_header_len(skb));
L
Linus Torvalds 已提交
1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355
		*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.
	 */
W
WANG Cong 已提交
1356
	skb->ignore_df = ip_sk_ignore_df(sk);
L
Linus Torvalds 已提交
1357 1358

	/* DF bit is set when we want to see DF on outgoing frames.
W
WANG Cong 已提交
1359
	 * If ignore_df is set too, we still allow to fragment this frame
L
Linus Torvalds 已提交
1360
	 * locally. */
1361 1362
	if (inet->pmtudisc == IP_PMTUDISC_DO ||
	    inet->pmtudisc == IP_PMTUDISC_PROBE ||
1363 1364
	    (skb->len <= dst_mtu(&rt->dst) &&
	     ip_dont_fragment(sk, &rt->dst)))
L
Linus Torvalds 已提交
1365 1366
		df = htons(IP_DF);

1367 1368
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1369

1370 1371 1372
	if (cork->ttl != 0)
		ttl = cork->ttl;
	else if (rt->rt_type == RTN_MULTICAST)
L
Linus Torvalds 已提交
1373 1374
		ttl = inet->mc_ttl;
	else
1375
		ttl = ip_select_ttl(inet, &rt->dst);
L
Linus Torvalds 已提交
1376

1377
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
1378 1379
	iph->version = 4;
	iph->ihl = 5;
1380
	iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
L
Linus Torvalds 已提交
1381 1382 1383
	iph->frag_off = df;
	iph->ttl = ttl;
	iph->protocol = sk->sk_protocol;
1384
	ip_copy_addrs(iph, fl4);
E
Eric Dumazet 已提交
1385
	ip_select_ident(skb, sk);
L
Linus Torvalds 已提交
1386

1387 1388 1389 1390 1391
	if (opt) {
		iph->ihl += opt->optlen>>2;
		ip_options_build(skb, opt, cork->addr, rt, 0);
	}

1392
	skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1393
	skb->mark = sk->sk_mark;
1394 1395 1396 1397
	/*
	 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
	 * on dst refcount
	 */
1398
	cork->dst = NULL;
1399
	skb_dst_set(skb, &rt->dst);
L
Linus Torvalds 已提交
1400

1401
	if (iph->protocol == IPPROTO_ICMP)
1402
		icmp_out_count(net, ((struct icmphdr *)
1403 1404
			skb_transport_header(skb))->type);

1405 1406 1407 1408 1409
	ip_cork_release(cork);
out:
	return skb;
}

E
Eric Dumazet 已提交
1410
int ip_send_skb(struct net *net, struct sk_buff *skb)
1411 1412 1413
{
	int err;

H
Herbert Xu 已提交
1414
	err = ip_local_out(skb);
L
Linus Torvalds 已提交
1415 1416
	if (err) {
		if (err > 0)
E
Eric Dumazet 已提交
1417
			err = net_xmit_errno(err);
L
Linus Torvalds 已提交
1418
		if (err)
1419
			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1420 1421 1422 1423 1424
	}

	return err;
}

1425
int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1426
{
1427 1428
	struct sk_buff *skb;

1429
	skb = ip_finish_skb(sk, fl4);
1430 1431 1432 1433
	if (!skb)
		return 0;

	/* Netfilter gets whole the not fragmented skb. */
E
Eric Dumazet 已提交
1434
	return ip_send_skb(sock_net(sk), skb);
1435 1436
}

L
Linus Torvalds 已提交
1437 1438 1439
/*
 *	Throw away all pending data on the socket.
 */
1440 1441 1442
static void __ip_flush_pending_frames(struct sock *sk,
				      struct sk_buff_head *queue,
				      struct inet_cork *cork)
L
Linus Torvalds 已提交
1443 1444 1445
{
	struct sk_buff *skb;

1446
	while ((skb = __skb_dequeue_tail(queue)) != NULL)
L
Linus Torvalds 已提交
1447 1448
		kfree_skb(skb);

1449 1450 1451 1452 1453
	ip_cork_release(cork);
}

void ip_flush_pending_frames(struct sock *sk)
{
1454
	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
L
Linus Torvalds 已提交
1455 1456
}

1457
struct sk_buff *ip_make_skb(struct sock *sk,
1458
			    struct flowi4 *fl4,
1459 1460 1461 1462 1463 1464
			    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)
{
1465
	struct inet_cork cork;
1466 1467 1468 1469 1470 1471 1472 1473
	struct sk_buff_head queue;
	int err;

	if (flags & MSG_PROBE)
		return NULL;

	__skb_queue_head_init(&queue);

1474 1475
	cork.flags = 0;
	cork.addr = 0;
1476
	cork.opt = NULL;
1477 1478 1479 1480
	err = ip_setup_cork(sk, &cork, ipc, rtp);
	if (err)
		return ERR_PTR(err);

1481 1482
	err = __ip_append_data(sk, fl4, &queue, &cork,
			       &current->task_frag, getfrag,
1483 1484 1485 1486 1487 1488
			       from, length, transhdrlen, flags);
	if (err) {
		__ip_flush_pending_frames(sk, &queue, &cork);
		return ERR_PTR(err);
	}

1489
	return __ip_make_skb(sk, fl4, &queue, &cork);
1490
}
L
Linus Torvalds 已提交
1491 1492 1493 1494

/*
 *	Fetch data from kernel space and fill in checksum if needed.
 */
1495
static int ip_reply_glue_bits(void *dptr, char *to, int offset,
L
Linus Torvalds 已提交
1496 1497
			      int len, int odd, struct sk_buff *skb)
{
1498
	__wsum csum;
L
Linus Torvalds 已提交
1499 1500 1501

	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
	skb->csum = csum_block_add(skb->csum, csum, odd);
1502
	return 0;
L
Linus Torvalds 已提交
1503 1504
}

1505
/*
L
Linus Torvalds 已提交
1506
 *	Generic function to send a packet as reply to another packet.
1507
 *	Used to send some TCP resets/acks so far.
L
Linus Torvalds 已提交
1508
 */
1509
void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1510 1511 1512
			   const struct ip_options *sopt,
			   __be32 daddr, __be32 saddr,
			   const struct ip_reply_arg *arg,
1513
			   unsigned int len)
L
Linus Torvalds 已提交
1514
{
1515
	struct ip_options_data replyopts;
L
Linus Torvalds 已提交
1516
	struct ipcm_cookie ipc;
1517
	struct flowi4 fl4;
E
Eric Dumazet 已提交
1518
	struct rtable *rt = skb_rtable(skb);
1519
	struct net *net = sock_net(sk);
1520
	struct sk_buff *nskb;
1521
	int err;
L
Linus Torvalds 已提交
1522

1523
	if (__ip_options_echo(&replyopts.opt.opt, skb, sopt))
L
Linus Torvalds 已提交
1524 1525
		return;

1526
	ipc.addr = daddr;
L
Linus Torvalds 已提交
1527
	ipc.opt = NULL;
1528
	ipc.tx_flags = 0;
1529 1530
	ipc.ttl = 0;
	ipc.tos = -1;
L
Linus Torvalds 已提交
1531

1532
	if (replyopts.opt.opt.optlen) {
L
Linus Torvalds 已提交
1533 1534
		ipc.opt = &replyopts.opt;

1535 1536
		if (replyopts.opt.opt.srr)
			daddr = replyopts.opt.opt.faddr;
L
Linus Torvalds 已提交
1537 1538
	}

1539 1540
	flowi4_init_output(&fl4, arg->bound_dev_if,
			   IP4_REPLY_MARK(net, skb->mark),
1541
			   RT_TOS(arg->tos),
1542
			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1543
			   ip_reply_arg_flowi_flags(arg),
1544
			   daddr, saddr,
1545 1546
			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1547
	rt = ip_route_output_key(net, &fl4);
1548 1549
	if (IS_ERR(rt))
		return;
L
Linus Torvalds 已提交
1550

1551
	inet_sk(sk)->tos = arg->tos;
L
Linus Torvalds 已提交
1552 1553

	sk->sk_priority = skb->priority;
1554
	sk->sk_protocol = ip_hdr(skb)->protocol;
1555
	sk->sk_bound_dev_if = arg->bound_dev_if;
1556
	sk->sk_sndbuf = sysctl_wmem_default;
1557 1558 1559 1560 1561 1562 1563
	err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
			     len, 0, &ipc, &rt, MSG_DONTWAIT);
	if (unlikely(err)) {
		ip_flush_pending_frames(sk);
		goto out;
	}

1564 1565
	nskb = skb_peek(&sk->sk_write_queue);
	if (nskb) {
L
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		if (arg->csumoffset >= 0)
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			*((__sum16 *)skb_transport_header(nskb) +
			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
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								arg->csum));
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		nskb->ip_summed = CHECKSUM_NONE;
		skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
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		ip_push_pending_frames(sk, &fl4);
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	}
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out:
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	ip_rt_put(rt);
}

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

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#if defined(CONFIG_IP_MULTICAST)
	igmp_mc_init();
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#endif
}