ip_output.c 39.8 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>
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#include <net/lwtunnel.h>
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#include <linux/igmp.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_bridge.h>
#include <linux/netlink.h>
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#include <linux/tcp.h>
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static int
ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
	    unsigned int mtu,
	    int (*output)(struct net *, struct sock *, struct sk_buff *));
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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 net *net, struct sock *sk, struct sk_buff *skb)
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{
	struct iphdr *iph = ip_hdr(skb);

	iph->tot_len = htons(skb->len);
	ip_send_check(iph);
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	/* if egress device is enslaved to an L3 master device pass the
	 * skb to its handler for processing
	 */
	skb = l3mdev_ip_out(sk, skb);
	if (unlikely(!skb))
		return 0;

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	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
		       net, sk, skb, NULL, skb_dst(skb)->dev,
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		       dst_output);
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}

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

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	err = __ip_local_out(net, sk, skb);
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	if (likely(err == 1))
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		err = dst_output(net, sk, skb);
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	return err;
}
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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.
 *
 */
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int ip_build_and_send_pkt(struct sk_buff *skb, const 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 net *net = sock_net(sk);
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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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	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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	if (ip_dont_fragment(sk, &rt->dst)) {
		iph->frag_off = htons(IP_DF);
		iph->id = 0;
	} else {
		iph->frag_off = 0;
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		__ip_select_ident(net, iph, 1);
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	}
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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(net, skb->sk, skb);
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}
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EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);

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static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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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) {
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		IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
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	} else if (rt->rt_type == RTN_BROADCAST)
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		IP_UPD_PO_STATS(net, 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));
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		if (!skb2) {
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			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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	if (lwtunnel_xmit_redirect(dst->lwtstate)) {
		int res = lwtunnel_xmit(skb);

		if (res < 0 || res == LWTUNNEL_XMIT_DONE)
			return res;
	}

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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 net *net, struct sock *sk,
				struct sk_buff *skb, unsigned int mtu)
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{
	netdev_features_t features;
	struct sk_buff *segs;
	int ret = 0;

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	/* common case: fragmentation of segments is not allowed,
	 * or seglen is <= mtu
	 */
	if (((IPCB(skb)->flags & IPSKB_FRAG_SEGS) == 0) ||
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	      skb_gso_validate_mtu(skb, mtu))
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		return ip_finish_output2(net, sk, skb);
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	/* 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);
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	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
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	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;
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		err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
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		if (err && ret == 0)
			ret = err;
		segs = nskb;
	} while (segs);

	return ret;
}

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static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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	unsigned int mtu;

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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) {
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		IPCB(skb)->flags |= IPSKB_REROUTED;
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		return dst_output(net, sk, skb);
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	}
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#endif
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	mtu = ip_skb_dst_mtu(sk, skb);
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	if (skb_is_gso(skb))
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		return ip_finish_output_gso(net, sk, skb, mtu);
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	if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
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		return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
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	return ip_finish_output2(net, sk, skb);
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}

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int ip_mc_output(struct net *net, 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(net, 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,
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					net, sk, 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,
				net, sk, newskb, NULL, newskb->dev,
				dev_loopback_xmit);
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	}

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	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
			    net, sk, 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 net *net, 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(net, 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,
			    net, sk, 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 net *net = sock_net(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)
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		goto packet_routed;

	/* Make sure we can route this packet. */
	rt = (struct rtable *)__sk_dst_check(sk, 0);
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	if (!rt) {
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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(net, 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(net, skb, sk,
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			     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(net, sk, skb);
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	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(net, 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_IP_VS)
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	to->ipvs_property = from->ipvs_property;
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#endif
504
	skb_copy_secmark(to, from);
L
Linus Torvalds 已提交
505 506
}

507
static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
508
		       unsigned int mtu,
509
		       int (*output)(struct net *, struct sock *, struct sk_buff *))
510 511 512
{
	struct iphdr *iph = ip_hdr(skb);

513
	if ((iph->frag_off & htons(IP_DF)) == 0)
514
		return ip_do_fragment(net, sk, skb, output);
515 516

	if (unlikely(!skb->ignore_df ||
517 518
		     (IPCB(skb)->frag_max_size &&
		      IPCB(skb)->frag_max_size > mtu))) {
519
		IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
520 521 522 523 524 525
		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
			  htonl(mtu));
		kfree_skb(skb);
		return -EMSGSIZE;
	}

526
	return ip_do_fragment(net, sk, skb, output);
527 528
}

L
Linus Torvalds 已提交
529 530 531 532 533 534 535
/*
 *	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.
 */

536 537
int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
		   int (*output)(struct net *, struct sock *, struct sk_buff *))
L
Linus Torvalds 已提交
538 539 540 541
{
	struct iphdr *iph;
	int ptr;
	struct sk_buff *skb2;
542
	unsigned int mtu, hlen, left, len, ll_rs;
L
Linus Torvalds 已提交
543
	int offset;
544
	__be16 not_last_frag;
E
Eric Dumazet 已提交
545
	struct rtable *rt = skb_rtable(skb);
L
Linus Torvalds 已提交
546 547
	int err = 0;

548 549 550 551 552
	/* for offloaded checksums cleanup checksum before fragmentation */
	if (skb->ip_summed == CHECKSUM_PARTIAL &&
	    (err = skb_checksum_help(skb)))
		goto fail;

L
Linus Torvalds 已提交
553 554 555 556
	/*
	 *	Point into the IP datagram header.
	 */

557
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
558

559
	mtu = ip_skb_dst_mtu(sk, skb);
560 561
	if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
		mtu = IPCB(skb)->frag_max_size;
L
Linus Torvalds 已提交
562 563 564 565 566 567

	/*
	 *	Setup starting values.
	 */

	hlen = iph->ihl * 4;
568
	mtu = mtu - hlen;	/* Size of data space */
H
Herbert Xu 已提交
569
	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
L
Linus Torvalds 已提交
570 571 572 573 574 575 576 577

	/* 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.
	 */
578
	if (skb_has_frag_list(skb)) {
579
		struct sk_buff *frag, *frag2;
L
Linus Torvalds 已提交
580 581 582 583
		int first_len = skb_pagelen(skb);

		if (first_len - hlen > mtu ||
		    ((first_len - hlen) & 7) ||
584
		    ip_is_fragment(iph) ||
L
Linus Torvalds 已提交
585 586 587
		    skb_cloned(skb))
			goto slow_path;

588
		skb_walk_frags(skb, frag) {
L
Linus Torvalds 已提交
589 590 591 592
			/* Correct geometry. */
			if (frag->len > mtu ||
			    ((frag->len & 7) && frag->next) ||
			    skb_headroom(frag) < hlen)
593
				goto slow_path_clean;
L
Linus Torvalds 已提交
594 595 596

			/* Partially cloned skb? */
			if (skb_shared(frag))
597
				goto slow_path_clean;
598 599 600 601 602 603

			BUG_ON(frag->sk);
			if (skb->sk) {
				frag->sk = skb->sk;
				frag->destructor = sock_wfree;
			}
604
			skb->truesize -= frag->truesize;
L
Linus Torvalds 已提交
605 606 607 608 609 610 611
		}

		/* Everything is OK. Generate! */

		err = 0;
		offset = 0;
		frag = skb_shinfo(skb)->frag_list;
612
		skb_frag_list_init(skb);
L
Linus Torvalds 已提交
613 614 615 616 617 618 619 620 621 622 623
		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;
624
				skb_reset_transport_header(frag);
625 626
				__skb_push(frag, hlen);
				skb_reset_network_header(frag);
627
				memcpy(skb_network_header(frag), iph, hlen);
628
				iph = ip_hdr(frag);
L
Linus Torvalds 已提交
629 630 631 632 633 634
				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);
635
				if (frag->next)
L
Linus Torvalds 已提交
636 637 638 639 640
					iph->frag_off |= htons(IP_MF);
				/* Ready, complete checksum */
				ip_send_check(iph);
			}

641
			err = output(net, sk, skb);
L
Linus Torvalds 已提交
642

643
			if (!err)
644
				IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
645 646 647 648 649 650 651 652 653
			if (err || !frag)
				break;

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

		if (err == 0) {
654
			IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
655 656 657 658 659 660 661 662
			return 0;
		}

		while (frag) {
			skb = frag->next;
			kfree_skb(frag);
			frag = skb;
		}
663
		IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
664
		return err;
665 666 667 668 669 670 671 672 673

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
674 675 676
	}

slow_path:
677
	iph = ip_hdr(skb);
678

L
Linus Torvalds 已提交
679
	left = skb->len - hlen;		/* Space per frame */
680
	ptr = hlen;		/* Where to start from */
L
Linus Torvalds 已提交
681

682
	ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
683

L
Linus Torvalds 已提交
684 685 686 687 688 689 690 691 692 693 694
	/*
	 *	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
695
	while (left > 0) {
L
Linus Torvalds 已提交
696 697 698 699
		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
700
		/* IF: we are not sending up to and including the packet end
L
Linus Torvalds 已提交
701 702 703 704 705
		   then align the next start on an eight byte boundary */
		if (len < left)	{
			len &= ~7;
		}

706 707 708
		/* Allocate buffer */
		skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
		if (!skb2) {
L
Linus Torvalds 已提交
709 710 711 712 713 714 715 716 717 718 719
			err = -ENOMEM;
			goto fail;
		}

		/*
		 *	Set up data on packet
		 */

		ip_copy_metadata(skb2, skb);
		skb_reserve(skb2, ll_rs);
		skb_put(skb2, len + hlen);
720
		skb_reset_network_header(skb2);
721
		skb2->transport_header = skb2->network_header + hlen;
L
Linus Torvalds 已提交
722 723 724 725 726 727 728 729 730 731 732 733 734

		/*
		 *	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.
		 */

735
		skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
L
Linus Torvalds 已提交
736 737 738 739

		/*
		 *	Copy a block of the IP datagram.
		 */
740
		if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
L
Linus Torvalds 已提交
741 742 743 744 745 746
			BUG();
		left -= len;

		/*
		 *	Fill in the new header fields.
		 */
747
		iph = ip_hdr(skb2);
L
Linus Torvalds 已提交
748 749
		iph->frag_off = htons((offset >> 3));

750 751 752
		if (IPCB(skb)->flags & IPSKB_FRAG_PMTU)
			iph->frag_off |= htons(IP_DF);

L
Linus Torvalds 已提交
753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777
		/* 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);

778
		err = output(net, sk, skb2);
L
Linus Torvalds 已提交
779 780
		if (err)
			goto fail;
781

782
		IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
783
	}
784
	consume_skb(skb);
785
	IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
786 787 788
	return err;

fail:
789
	kfree_skb(skb);
790
	IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
791 792
	return err;
}
793
EXPORT_SYMBOL(ip_do_fragment);
794

L
Linus Torvalds 已提交
795 796 797
int
ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
798
	struct msghdr *msg = from;
L
Linus Torvalds 已提交
799

800
	if (skb->ip_summed == CHECKSUM_PARTIAL) {
801
		if (copy_from_iter(to, len, &msg->msg_iter) != len)
L
Linus Torvalds 已提交
802 803
			return -EFAULT;
	} else {
804
		__wsum csum = 0;
805
		if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len)
L
Linus Torvalds 已提交
806 807 808 809 810
			return -EFAULT;
		skb->csum = csum_block_add(skb->csum, csum, odd);
	}
	return 0;
}
E
Eric Dumazet 已提交
811
EXPORT_SYMBOL(ip_generic_getfrag);
L
Linus Torvalds 已提交
812

813
static inline __wsum
L
Linus Torvalds 已提交
814 815 816
csum_page(struct page *page, int offset, int copy)
{
	char *kaddr;
817
	__wsum csum;
L
Linus Torvalds 已提交
818 819 820 821 822 823
	kaddr = kmap(page);
	csum = csum_partial(kaddr + offset, copy, 0);
	kunmap(page);
	return csum;
}

A
Adrian Bunk 已提交
824
static inline int ip_ufo_append_data(struct sock *sk,
825
			struct sk_buff_head *queue,
826 827 828
			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,
829
			int transhdrlen, int maxfraglen, unsigned int flags)
830 831 832 833 834 835 836 837
{
	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
	 */
838 839
	skb = skb_peek_tail(queue);
	if (!skb) {
840 841 842 843
		skb = sock_alloc_send_skb(sk,
			hh_len + fragheaderlen + transhdrlen + 20,
			(flags & MSG_DONTWAIT), &err);

844
		if (!skb)
845 846 847 848 849 850
			return err;

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

		/* create space for UDP/IP header */
851
		skb_put(skb, fragheaderlen + transhdrlen);
852 853

		/* initialize network header pointer */
854
		skb_reset_network_header(skb);
855 856

		/* initialize protocol header pointer */
857
		skb->transport_header = skb->network_header + fragheaderlen;
858 859 860

		skb->csum = 0;

861
		__skb_queue_tail(queue, skb);
862 863
	} else if (skb_is_gso(skb)) {
		goto append;
864
	}
865

866 867 868 869 870 871
	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:
872 873
	return skb_append_datato_frags(sk, skb, getfrag, from,
				       (length - transhdrlen));
874 875
}

876 877 878
static int __ip_append_data(struct sock *sk,
			    struct flowi4 *fl4,
			    struct sk_buff_head *queue,
879
			    struct inet_cork *cork,
880
			    struct page_frag *pfrag,
881 882 883 884
			    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
885 886 887 888
{
	struct inet_sock *inet = inet_sk(sk);
	struct sk_buff *skb;

889
	struct ip_options *opt = cork->opt;
L
Linus Torvalds 已提交
890 891 892 893 894 895
	int hh_len;
	int exthdrlen;
	int mtu;
	int copy;
	int err;
	int offset = 0;
896
	unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
L
Linus Torvalds 已提交
897
	int csummode = CHECKSUM_NONE;
898
	struct rtable *rt = (struct rtable *)cork->dst;
899
	u32 tskey = 0;
L
Linus Torvalds 已提交
900

901 902 903
	skb = skb_peek_tail(queue);

	exthdrlen = !skb ? rt->dst.header_len : 0;
904
	mtu = cork->fragsize;
905 906 907
	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
908

909
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
L
Linus Torvalds 已提交
910 911 912

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
W
WANG Cong 已提交
913
	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
L
Linus Torvalds 已提交
914

915
	if (cork->length + length > maxnonfragsize - fragheaderlen) {
916
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
917
			       mtu - (opt ? opt->optlen : 0));
L
Linus Torvalds 已提交
918 919 920 921 922 923 924 925 926
		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 &&
927
	    rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
928
	    !(flags & MSG_MORE) &&
L
Linus Torvalds 已提交
929
	    !exthdrlen)
930
		csummode = CHECKSUM_PARTIAL;
L
Linus Torvalds 已提交
931

932
	cork->length += length;
933
	if (((length > mtu) || (skb && skb_is_gso(skb))) &&
934
	    (sk->sk_protocol == IPPROTO_UDP) &&
935
	    (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
936
	    (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx) {
937 938
		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
					 hh_len, fragheaderlen, transhdrlen,
939
					 maxfraglen, flags);
940
		if (err)
941 942 943
			goto error;
		return 0;
	}
L
Linus Torvalds 已提交
944 945 946 947 948 949 950 951

	/* 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.
	 */

952
	if (!skb)
L
Linus Torvalds 已提交
953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982
		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;

983
			if ((flags & MSG_MORE) &&
984
			    !(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
985 986
				alloclen = mtu;
			else
987
				alloclen = fraglen;
L
Linus Torvalds 已提交
988

989 990
			alloclen += exthdrlen;

L
Linus Torvalds 已提交
991 992 993 994 995
			/* 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.
			 */
996
			if (datalen == length + fraggap)
997
				alloclen += rt->dst.trailer_len;
998

L
Linus Torvalds 已提交
999
			if (transhdrlen) {
1000
				skb = sock_alloc_send_skb(sk,
L
Linus Torvalds 已提交
1001 1002 1003 1004 1005 1006
						alloclen + hh_len + 15,
						(flags & MSG_DONTWAIT), &err);
			} else {
				skb = NULL;
				if (atomic_read(&sk->sk_wmem_alloc) <=
				    2 * sk->sk_sndbuf)
1007
					skb = sock_wmalloc(sk,
L
Linus Torvalds 已提交
1008 1009
							   alloclen + hh_len + 15, 1,
							   sk->sk_allocation);
1010
				if (unlikely(!skb))
L
Linus Torvalds 已提交
1011 1012
					err = -ENOBUFS;
			}
1013
			if (!skb)
L
Linus Torvalds 已提交
1014 1015 1016 1017 1018 1019 1020 1021
				goto error;

			/*
			 *	Fill in the control structures
			 */
			skb->ip_summed = csummode;
			skb->csum = 0;
			skb_reserve(skb, hh_len);
1022 1023

			/* only the initial fragment is time stamped */
1024
			skb_shinfo(skb)->tx_flags = cork->tx_flags;
1025
			cork->tx_flags = 0;
1026 1027
			skb_shinfo(skb)->tskey = tskey;
			tskey = 0;
L
Linus Torvalds 已提交
1028 1029 1030 1031

			/*
			 *	Find where to start putting bytes.
			 */
1032
			data = skb_put(skb, fraglen + exthdrlen);
1033
			skb_set_network_header(skb, exthdrlen);
1034 1035
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
1036
			data += fragheaderlen + exthdrlen;
L
Linus Torvalds 已提交
1037 1038 1039 1040 1041 1042 1043 1044

			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;
1045
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063
			}

			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.
			 */
1064
			__skb_queue_tail(queue, skb);
L
Linus Torvalds 已提交
1065 1066 1067 1068 1069 1070
			continue;
		}

		if (copy > length)
			copy = length;

1071
		if (!(rt->dst.dev->features&NETIF_F_SG)) {
L
Linus Torvalds 已提交
1072 1073 1074
			unsigned int off;

			off = skb->len;
1075
			if (getfrag(from, skb_put(skb, copy),
L
Linus Torvalds 已提交
1076 1077 1078 1079 1080 1081 1082 1083
					offset, copy, off, skb) < 0) {
				__skb_trim(skb, off);
				err = -EFAULT;
				goto error;
			}
		} else {
			int i = skb_shinfo(skb)->nr_frags;

1084 1085
			err = -ENOMEM;
			if (!sk_page_frag_refill(sk, pfrag))
L
Linus Torvalds 已提交
1086
				goto error;
1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097

			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
1098
			}
1099 1100 1101 1102 1103 1104 1105 1106
			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
1107 1108
			skb->len += copy;
			skb->data_len += copy;
1109 1110
			skb->truesize += copy;
			atomic_add(copy, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1111 1112 1113 1114 1115 1116 1117
		}
		offset += copy;
		length -= copy;
	}

	return 0;

1118 1119
error_efault:
	err = -EFAULT;
L
Linus Torvalds 已提交
1120
error:
1121
	cork->length -= length;
P
Pavel Emelyanov 已提交
1122
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1123
	return err;
L
Linus Torvalds 已提交
1124 1125
}

1126 1127 1128
static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
			 struct ipcm_cookie *ipc, struct rtable **rtp)
{
1129
	struct ip_options_rcu *opt;
1130 1131 1132 1133 1134 1135 1136
	struct rtable *rt;

	/*
	 * setup for corking.
	 */
	opt = ipc->opt;
	if (opt) {
1137
		if (!cork->opt) {
1138 1139
			cork->opt = kmalloc(sizeof(struct ip_options) + 40,
					    sk->sk_allocation);
1140
			if (unlikely(!cork->opt))
1141 1142
				return -ENOBUFS;
		}
1143
		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1144 1145 1146 1147 1148 1149 1150 1151 1152 1153
		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;
1154 1155
	cork->fragsize = ip_sk_use_pmtu(sk) ?
			 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1156 1157
	cork->dst = &rt->dst;
	cork->length = 0;
1158 1159 1160
	cork->ttl = ipc->ttl;
	cork->tos = ipc->tos;
	cork->priority = ipc->priority;
1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176
	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.
 */
1177
int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190
		   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)) {
1191
		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1192 1193 1194 1195 1196 1197
		if (err)
			return err;
	} else {
		transhdrlen = 0;
	}

1198 1199
	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
				sk_page_frag(sk), getfrag,
1200 1201 1202
				from, length, transhdrlen, flags);
}

1203
ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
L
Linus Torvalds 已提交
1204 1205 1206 1207 1208 1209
		       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;
1210
	struct inet_cork *cork;
L
Linus Torvalds 已提交
1211 1212 1213 1214
	int hh_len;
	int mtu;
	int len;
	int err;
1215
	unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
L
Linus Torvalds 已提交
1216 1217 1218 1219 1220 1221 1222 1223 1224 1225

	if (inet->hdrincl)
		return -EPERM;

	if (flags&MSG_PROBE)
		return 0;

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

1226 1227 1228 1229
	cork = &inet->cork.base;
	rt = (struct rtable *)cork->dst;
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1230

1231
	if (!(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
1232 1233
		return -EOPNOTSUPP;

1234
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1235
	mtu = cork->fragsize;
L
Linus Torvalds 已提交
1236 1237 1238

	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
W
WANG Cong 已提交
1239
	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
L
Linus Torvalds 已提交
1240

1241
	if (cork->length + size > maxnonfragsize - fragheaderlen) {
1242 1243
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
			       mtu - (opt ? opt->optlen : 0));
L
Linus Torvalds 已提交
1244 1245 1246
		return -EMSGSIZE;
	}

1247 1248
	skb = skb_peek_tail(&sk->sk_write_queue);
	if (!skb)
L
Linus Torvalds 已提交
1249 1250
		return -EINVAL;

1251 1252
	if ((size + skb->len > mtu) &&
	    (sk->sk_protocol == IPPROTO_UDP) &&
1253
	    (rt->dst.dev->features & NETIF_F_UFO)) {
1254 1255 1256
		if (skb->ip_summed != CHECKSUM_PARTIAL)
			return -EOPNOTSUPP;

1257
		skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
H
Herbert Xu 已提交
1258
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1259
	}
1260
	cork->length += size;
1261

L
Linus Torvalds 已提交
1262
	while (size > 0) {
1263
		if (skb_is_gso(skb)) {
1264
			len = size;
1265
		} else {
1266 1267 1268 1269 1270 1271

			/* 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
1272 1273 1274 1275 1276
		if (len <= 0) {
			struct sk_buff *skb_prev;
			int alloclen;

			skb_prev = skb;
1277
			fraggap = skb_prev->len - maxfraglen;
L
Linus Torvalds 已提交
1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295

			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.
			 */
1296
			skb_put(skb, fragheaderlen + fraggap);
1297
			skb_reset_network_header(skb);
1298 1299
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
L
Linus Torvalds 已提交
1300
			if (fraggap) {
1301 1302
				skb->csum = skb_copy_and_csum_bits(skb_prev,
								   maxfraglen,
1303
						    skb_transport_header(skb),
1304
								   fraggap, 0);
L
Linus Torvalds 已提交
1305 1306
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
1307
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318
			}

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

		if (len > size)
			len = size;
1319 1320

		if (skb_append_pagefrags(skb, page, offset, len)) {
L
Linus Torvalds 已提交
1321 1322 1323 1324 1325
			err = -EMSGSIZE;
			goto error;
		}

		if (skb->ip_summed == CHECKSUM_NONE) {
1326
			__wsum csum;
L
Linus Torvalds 已提交
1327 1328 1329 1330 1331 1332
			csum = csum_page(page, offset, len);
			skb->csum = csum_block_add(skb->csum, csum, skb->len);
		}

		skb->len += len;
		skb->data_len += len;
1333 1334
		skb->truesize += len;
		atomic_add(len, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1335 1336 1337 1338 1339 1340
		offset += len;
		size -= len;
	}
	return 0;

error:
1341
	cork->length -= size;
P
Pavel Emelyanov 已提交
1342
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1343 1344 1345
	return err;
}

1346
static void ip_cork_release(struct inet_cork *cork)
1347
{
1348 1349 1350 1351 1352
	cork->flags &= ~IPCORK_OPT;
	kfree(cork->opt);
	cork->opt = NULL;
	dst_release(cork->dst);
	cork->dst = NULL;
1353 1354
}

L
Linus Torvalds 已提交
1355 1356 1357 1358
/*
 *	Combined all pending IP fragments on the socket as one IP datagram
 *	and push them out.
 */
1359
struct sk_buff *__ip_make_skb(struct sock *sk,
1360
			      struct flowi4 *fl4,
1361 1362
			      struct sk_buff_head *queue,
			      struct inet_cork *cork)
L
Linus Torvalds 已提交
1363 1364 1365 1366
{
	struct sk_buff *skb, *tmp_skb;
	struct sk_buff **tail_skb;
	struct inet_sock *inet = inet_sk(sk);
1367
	struct net *net = sock_net(sk);
L
Linus Torvalds 已提交
1368
	struct ip_options *opt = NULL;
1369
	struct rtable *rt = (struct rtable *)cork->dst;
L
Linus Torvalds 已提交
1370
	struct iphdr *iph;
1371
	__be16 df = 0;
L
Linus Torvalds 已提交
1372 1373
	__u8 ttl;

1374 1375
	skb = __skb_dequeue(queue);
	if (!skb)
L
Linus Torvalds 已提交
1376 1377 1378 1379
		goto out;
	tail_skb = &(skb_shinfo(skb)->frag_list);

	/* move skb->data to ip header from ext header */
1380
	if (skb->data < skb_network_header(skb))
1381
		__skb_pull(skb, skb_network_offset(skb));
1382
	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1383
		__skb_pull(tmp_skb, skb_network_header_len(skb));
L
Linus Torvalds 已提交
1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396
		*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
1397
	skb->ignore_df = ip_sk_ignore_df(sk);
L
Linus Torvalds 已提交
1398 1399

	/* DF bit is set when we want to see DF on outgoing frames.
W
WANG Cong 已提交
1400
	 * If ignore_df is set too, we still allow to fragment this frame
L
Linus Torvalds 已提交
1401
	 * locally. */
1402 1403
	if (inet->pmtudisc == IP_PMTUDISC_DO ||
	    inet->pmtudisc == IP_PMTUDISC_PROBE ||
1404 1405
	    (skb->len <= dst_mtu(&rt->dst) &&
	     ip_dont_fragment(sk, &rt->dst)))
L
Linus Torvalds 已提交
1406 1407
		df = htons(IP_DF);

1408 1409
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1410

1411 1412 1413
	if (cork->ttl != 0)
		ttl = cork->ttl;
	else if (rt->rt_type == RTN_MULTICAST)
L
Linus Torvalds 已提交
1414 1415
		ttl = inet->mc_ttl;
	else
1416
		ttl = ip_select_ttl(inet, &rt->dst);
L
Linus Torvalds 已提交
1417

1418
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
1419 1420
	iph->version = 4;
	iph->ihl = 5;
1421
	iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
L
Linus Torvalds 已提交
1422 1423 1424
	iph->frag_off = df;
	iph->ttl = ttl;
	iph->protocol = sk->sk_protocol;
1425
	ip_copy_addrs(iph, fl4);
1426
	ip_select_ident(net, skb, sk);
L
Linus Torvalds 已提交
1427

1428 1429 1430 1431 1432
	if (opt) {
		iph->ihl += opt->optlen>>2;
		ip_options_build(skb, opt, cork->addr, rt, 0);
	}

1433
	skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1434
	skb->mark = sk->sk_mark;
1435 1436 1437 1438
	/*
	 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
	 * on dst refcount
	 */
1439
	cork->dst = NULL;
1440
	skb_dst_set(skb, &rt->dst);
L
Linus Torvalds 已提交
1441

1442
	if (iph->protocol == IPPROTO_ICMP)
1443
		icmp_out_count(net, ((struct icmphdr *)
1444 1445
			skb_transport_header(skb))->type);

1446 1447 1448 1449 1450
	ip_cork_release(cork);
out:
	return skb;
}

E
Eric Dumazet 已提交
1451
int ip_send_skb(struct net *net, struct sk_buff *skb)
1452 1453 1454
{
	int err;

1455
	err = ip_local_out(net, skb->sk, skb);
L
Linus Torvalds 已提交
1456 1457
	if (err) {
		if (err > 0)
E
Eric Dumazet 已提交
1458
			err = net_xmit_errno(err);
L
Linus Torvalds 已提交
1459
		if (err)
1460
			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1461 1462 1463 1464 1465
	}

	return err;
}

1466
int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1467
{
1468 1469
	struct sk_buff *skb;

1470
	skb = ip_finish_skb(sk, fl4);
1471 1472 1473 1474
	if (!skb)
		return 0;

	/* Netfilter gets whole the not fragmented skb. */
E
Eric Dumazet 已提交
1475
	return ip_send_skb(sock_net(sk), skb);
1476 1477
}

L
Linus Torvalds 已提交
1478 1479 1480
/*
 *	Throw away all pending data on the socket.
 */
1481 1482 1483
static void __ip_flush_pending_frames(struct sock *sk,
				      struct sk_buff_head *queue,
				      struct inet_cork *cork)
L
Linus Torvalds 已提交
1484 1485 1486
{
	struct sk_buff *skb;

1487
	while ((skb = __skb_dequeue_tail(queue)) != NULL)
L
Linus Torvalds 已提交
1488 1489
		kfree_skb(skb);

1490 1491 1492 1493 1494
	ip_cork_release(cork);
}

void ip_flush_pending_frames(struct sock *sk)
{
1495
	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
L
Linus Torvalds 已提交
1496 1497
}

1498
struct sk_buff *ip_make_skb(struct sock *sk,
1499
			    struct flowi4 *fl4,
1500 1501 1502 1503 1504 1505
			    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)
{
1506
	struct inet_cork cork;
1507 1508 1509 1510 1511 1512 1513 1514
	struct sk_buff_head queue;
	int err;

	if (flags & MSG_PROBE)
		return NULL;

	__skb_queue_head_init(&queue);

1515 1516
	cork.flags = 0;
	cork.addr = 0;
1517
	cork.opt = NULL;
1518 1519 1520 1521
	err = ip_setup_cork(sk, &cork, ipc, rtp);
	if (err)
		return ERR_PTR(err);

1522 1523
	err = __ip_append_data(sk, fl4, &queue, &cork,
			       &current->task_frag, getfrag,
1524 1525 1526 1527 1528 1529
			       from, length, transhdrlen, flags);
	if (err) {
		__ip_flush_pending_frames(sk, &queue, &cork);
		return ERR_PTR(err);
	}

1530
	return __ip_make_skb(sk, fl4, &queue, &cork);
1531
}
L
Linus Torvalds 已提交
1532 1533 1534 1535

/*
 *	Fetch data from kernel space and fill in checksum if needed.
 */
1536
static int ip_reply_glue_bits(void *dptr, char *to, int offset,
L
Linus Torvalds 已提交
1537 1538
			      int len, int odd, struct sk_buff *skb)
{
1539
	__wsum csum;
L
Linus Torvalds 已提交
1540 1541 1542

	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
	skb->csum = csum_block_add(skb->csum, csum, odd);
1543
	return 0;
L
Linus Torvalds 已提交
1544 1545
}

1546
/*
L
Linus Torvalds 已提交
1547
 *	Generic function to send a packet as reply to another packet.
1548
 *	Used to send some TCP resets/acks so far.
L
Linus Torvalds 已提交
1549
 */
1550
void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1551 1552 1553
			   const struct ip_options *sopt,
			   __be32 daddr, __be32 saddr,
			   const struct ip_reply_arg *arg,
1554
			   unsigned int len)
L
Linus Torvalds 已提交
1555
{
1556
	struct ip_options_data replyopts;
L
Linus Torvalds 已提交
1557
	struct ipcm_cookie ipc;
1558
	struct flowi4 fl4;
E
Eric Dumazet 已提交
1559
	struct rtable *rt = skb_rtable(skb);
1560
	struct net *net = sock_net(sk);
1561
	struct sk_buff *nskb;
1562
	int err;
1563
	int oif;
L
Linus Torvalds 已提交
1564

1565
	if (__ip_options_echo(&replyopts.opt.opt, skb, sopt))
L
Linus Torvalds 已提交
1566 1567
		return;

1568
	ipc.addr = daddr;
L
Linus Torvalds 已提交
1569
	ipc.opt = NULL;
1570
	ipc.tx_flags = 0;
1571 1572
	ipc.ttl = 0;
	ipc.tos = -1;
L
Linus Torvalds 已提交
1573

1574
	if (replyopts.opt.opt.optlen) {
L
Linus Torvalds 已提交
1575 1576
		ipc.opt = &replyopts.opt;

1577 1578
		if (replyopts.opt.opt.srr)
			daddr = replyopts.opt.opt.faddr;
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	}

1581
	oif = arg->bound_dev_if;
1582
	oif = oif ? : skb->skb_iif;
1583 1584

	flowi4_init_output(&fl4, oif,
1585
			   IP4_REPLY_MARK(net, skb->mark),
1586
			   RT_TOS(arg->tos),
1587
			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1588
			   ip_reply_arg_flowi_flags(arg),
1589
			   daddr, saddr,
1590 1591
			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1592
	rt = ip_route_output_key(net, &fl4);
1593 1594
	if (IS_ERR(rt))
		return;
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1595

1596
	inet_sk(sk)->tos = arg->tos;
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	sk->sk_priority = skb->priority;
1599
	sk->sk_protocol = ip_hdr(skb)->protocol;
1600
	sk->sk_bound_dev_if = arg->bound_dev_if;
1601
	sk->sk_sndbuf = sysctl_wmem_default;
1602 1603 1604 1605 1606 1607 1608
	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;
	}

1609 1610
	nskb = skb_peek(&sk->sk_write_queue);
	if (nskb) {
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1611
		if (arg->csumoffset >= 0)
1612 1613
			*((__sum16 *)skb_transport_header(nskb) +
			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1614
								arg->csum));
1615
		nskb->ip_summed = CHECKSUM_NONE;
1616
		ip_push_pending_frames(sk, &fl4);
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1617
	}
1618
out:
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1619 1620 1621 1622 1623 1624 1625 1626
	ip_rt_put(rt);
}

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

1627 1628
#if defined(CONFIG_IP_MULTICAST)
	igmp_mc_init();
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#endif
}