ip_output.c 37.9 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7
/*
 * 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.
 *
8
 * Authors:	Ross Biro
L
Linus Torvalds 已提交
9 10 11 12 13 14 15 16 17 18 19 20 21 22
 *		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.
23
 *		Bradford Johnson:	Fix faulty handling of some frames when
L
Linus Torvalds 已提交
24 25 26 27 28 29 30 31 32 33
 *					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.
34 35 36
 *		Andi Kleen	:	Split fast and slow ip_build_xmit path
 *					for decreased register pressure on x86
 *					and more readibility.
L
Linus Torvalds 已提交
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
 *		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>
A
Al Viro 已提交
52
#include <linux/highmem.h>
53
#include <linux/slab.h>
L
Linus Torvalds 已提交
54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

#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>
69
#include <net/xfrm.h>
L
Linus Torvalds 已提交
70 71 72 73 74 75 76 77 78 79 80
#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>
81
#include <linux/tcp.h>
L
Linus Torvalds 已提交
82

83
int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
84
EXPORT_SYMBOL(sysctl_ip_default_ttl);
L
Linus Torvalds 已提交
85 86 87 88 89 90 91

/* Generate a checksum for an outgoing IP datagram. */
__inline__ void ip_send_check(struct iphdr *iph)
{
	iph->check = 0;
	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
}
E
Eric Dumazet 已提交
92
EXPORT_SYMBOL(ip_send_check);
L
Linus Torvalds 已提交
93

H
Herbert Xu 已提交
94 95 96 97 98 99
int __ip_local_out(struct sk_buff *skb)
{
	struct iphdr *iph = ip_hdr(skb);

	iph->tot_len = htons(skb->len);
	ip_send_check(iph);
100 101
	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
		       skb_dst(skb)->dev, dst_output);
H
Herbert Xu 已提交
102 103 104 105 106 107 108 109 110 111 112 113 114 115
}

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

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

	return err;
}
EXPORT_SYMBOL_GPL(ip_local_out);

L
Linus Torvalds 已提交
116 117 118 119 120
static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
{
	int ttl = inet->uc_ttl;

	if (ttl < 0)
121
		ttl = ip4_dst_hoplimit(dst);
L
Linus Torvalds 已提交
122 123 124
	return ttl;
}

125
/*
L
Linus Torvalds 已提交
126 127 128 129
 *		Add an ip header to a skbuff and send it out.
 *
 */
int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
130
			  __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
L
Linus Torvalds 已提交
131 132
{
	struct inet_sock *inet = inet_sk(sk);
E
Eric Dumazet 已提交
133
	struct rtable *rt = skb_rtable(skb);
L
Linus Torvalds 已提交
134 135 136
	struct iphdr *iph;

	/* Build the IP header. */
137
	skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
138
	skb_reset_network_header(skb);
139
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
140 141 142
	iph->version  = 4;
	iph->ihl      = 5;
	iph->tos      = inet->tos;
143
	if (ip_dont_fragment(sk, &rt->dst))
L
Linus Torvalds 已提交
144 145 146
		iph->frag_off = htons(IP_DF);
	else
		iph->frag_off = 0;
147
	iph->ttl      = ip_select_ttl(inet, &rt->dst);
148 149
	iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
	iph->saddr    = saddr;
L
Linus Torvalds 已提交
150
	iph->protocol = sk->sk_protocol;
151
	ip_select_ident(iph, &rt->dst, sk);
L
Linus Torvalds 已提交
152

153 154 155
	if (opt && opt->opt.optlen) {
		iph->ihl += opt->opt.optlen>>2;
		ip_options_build(skb, &opt->opt, daddr, rt, 0);
L
Linus Torvalds 已提交
156 157 158
	}

	skb->priority = sk->sk_priority;
159
	skb->mark = sk->sk_mark;
L
Linus Torvalds 已提交
160 161

	/* Send it out. */
H
Herbert Xu 已提交
162
	return ip_local_out(skb);
L
Linus Torvalds 已提交
163
}
164 165
EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);

L
Linus Torvalds 已提交
166 167
static inline int ip_finish_output2(struct sk_buff *skb)
{
E
Eric Dumazet 已提交
168
	struct dst_entry *dst = skb_dst(skb);
169
	struct rtable *rt = (struct rtable *)dst;
L
Linus Torvalds 已提交
170
	struct net_device *dev = dst->dev;
171
	unsigned int hh_len = LL_RESERVED_SPACE(dev);
172
	struct neighbour *neigh;
173
	u32 nexthop;
L
Linus Torvalds 已提交
174

175 176 177 178
	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);
179

L
Linus Torvalds 已提交
180
	/* Be paranoid, rather than too clever. */
181
	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
L
Linus Torvalds 已提交
182 183 184 185 186 187 188 189 190
		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);
191
		consume_skb(skb);
L
Linus Torvalds 已提交
192 193 194
		skb = skb2;
	}

195
	rcu_read_lock_bh();
J
Julian Anastasov 已提交
196
	nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
197 198 199
	neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
	if (unlikely(!neigh))
		neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
200
	if (!IS_ERR(neigh)) {
201
		int res = dst_neigh_output(dst, neigh, skb);
202

203
		rcu_read_unlock_bh();
204 205
		return res;
	}
206
	rcu_read_unlock_bh();
207

208 209
	net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
			    __func__);
L
Linus Torvalds 已提交
210 211 212 213
	kfree_skb(skb);
	return -EINVAL;
}

J
John Heffner 已提交
214 215 216 217 218
static inline int ip_skb_dst_mtu(struct sk_buff *skb)
{
	struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;

	return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
E
Eric Dumazet 已提交
219
	       skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
J
John Heffner 已提交
220 221
}

P
Patrick McHardy 已提交
222
static int ip_finish_output(struct sk_buff *skb)
L
Linus Torvalds 已提交
223
{
224 225
#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
	/* Policy lookup after SNAT yielded a new policy */
E
Eric Dumazet 已提交
226
	if (skb_dst(skb)->xfrm != NULL) {
227 228 229
		IPCB(skb)->flags |= IPSKB_REROUTED;
		return dst_output(skb);
	}
230
#endif
J
John Heffner 已提交
231
	if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
232 233 234
		return ip_fragment(skb, ip_finish_output2);
	else
		return ip_finish_output2(skb);
L
Linus Torvalds 已提交
235 236 237 238 239
}

int ip_mc_output(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;
E
Eric Dumazet 已提交
240
	struct rtable *rt = skb_rtable(skb);
241
	struct net_device *dev = rt->dst.dev;
L
Linus Torvalds 已提交
242 243 244 245

	/*
	 *	If the indicated interface is up and running, send the packet.
	 */
246
	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
L
Linus Torvalds 已提交
247 248 249 250 251 252 253 254 255

	skb->dev = dev;
	skb->protocol = htons(ETH_P_IP);

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

	if (rt->rt_flags&RTCF_MULTICAST) {
256
		if (sk_mc_loop(sk)
L
Linus Torvalds 已提交
257 258 259 260 261 262 263 264 265
#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.
		 */
266 267 268
		    &&
		    ((rt->rt_flags & RTCF_LOCAL) ||
		     !(IPCB(skb)->flags & IPSKB_FORWARDED))
L
Linus Torvalds 已提交
269
#endif
270
		   ) {
L
Linus Torvalds 已提交
271 272
			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
			if (newskb)
273 274
				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
					newskb, NULL, newskb->dev,
275
					dev_loopback_xmit);
L
Linus Torvalds 已提交
276 277 278 279
		}

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

280
		if (ip_hdr(skb)->ttl == 0) {
L
Linus Torvalds 已提交
281 282 283 284 285 286 287 288
			kfree_skb(skb);
			return 0;
		}
	}

	if (rt->rt_flags&RTCF_BROADCAST) {
		struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
		if (newskb)
289
			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
290
				NULL, newskb->dev, dev_loopback_xmit);
L
Linus Torvalds 已提交
291 292
	}

293 294
	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
			    skb->dev, ip_finish_output,
295
			    !(IPCB(skb)->flags & IPSKB_REROUTED));
L
Linus Torvalds 已提交
296 297 298 299
}

int ip_output(struct sk_buff *skb)
{
E
Eric Dumazet 已提交
300
	struct net_device *dev = skb_dst(skb)->dev;
301

302
	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
L
Linus Torvalds 已提交
303

304 305 306
	skb->dev = dev;
	skb->protocol = htons(ETH_P_IP);

307
	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
308
			    ip_finish_output,
309
			    !(IPCB(skb)->flags & IPSKB_REROUTED));
L
Linus Torvalds 已提交
310 311
}

312 313 314 315 316 317 318 319 320 321 322 323 324 325
/*
 * 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));
}

326
int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
L
Linus Torvalds 已提交
327
{
328
	struct sock *sk = skb->sk;
L
Linus Torvalds 已提交
329
	struct inet_sock *inet = inet_sk(sk);
330
	struct ip_options_rcu *inet_opt;
331
	struct flowi4 *fl4;
L
Linus Torvalds 已提交
332 333
	struct rtable *rt;
	struct iphdr *iph;
334
	int res;
L
Linus Torvalds 已提交
335 336 337 338

	/* Skip all of this if the packet is already routed,
	 * f.e. by something like SCTP.
	 */
339
	rcu_read_lock();
340
	inet_opt = rcu_dereference(inet->inet_opt);
341
	fl4 = &fl->u.ip4;
E
Eric Dumazet 已提交
342
	rt = skb_rtable(skb);
L
Linus Torvalds 已提交
343 344 345 346 347 348
	if (rt != NULL)
		goto packet_routed;

	/* Make sure we can route this packet. */
	rt = (struct rtable *)__sk_dst_check(sk, 0);
	if (rt == NULL) {
A
Al Viro 已提交
349
		__be32 daddr;
L
Linus Torvalds 已提交
350 351

		/* Use correct destination address if we have options. */
E
Eric Dumazet 已提交
352
		daddr = inet->inet_daddr;
353 354
		if (inet_opt && inet_opt->opt.srr)
			daddr = inet_opt->opt.faddr;
L
Linus Torvalds 已提交
355

356 357 358 359
		/* If this fails, retransmit mechanism of transport layer will
		 * keep trying until route appears or the connection times
		 * itself out.
		 */
360
		rt = ip_route_output_ports(sock_net(sk), fl4, sk,
361 362 363 364 365 366 367 368
					   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;
369
		sk_setup_caps(sk, &rt->dst);
L
Linus Torvalds 已提交
370
	}
371
	skb_dst_set_noref(skb, &rt->dst);
L
Linus Torvalds 已提交
372 373

packet_routed:
J
Julian Anastasov 已提交
374
	if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
L
Linus Torvalds 已提交
375 376 377
		goto no_route;

	/* OK, we know where to send it, allocate and build IP header. */
378
	skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
379
	skb_reset_network_header(skb);
380
	iph = ip_hdr(skb);
381
	*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
382
	if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
L
Linus Torvalds 已提交
383 384 385
		iph->frag_off = htons(IP_DF);
	else
		iph->frag_off = 0;
386
	iph->ttl      = ip_select_ttl(inet, &rt->dst);
L
Linus Torvalds 已提交
387
	iph->protocol = sk->sk_protocol;
388 389
	ip_copy_addrs(iph, fl4);

L
Linus Torvalds 已提交
390 391
	/* Transport layer set skb->h.foo itself. */

392 393 394
	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);
L
Linus Torvalds 已提交
395 396
	}

397
	ip_select_ident_more(iph, &rt->dst, sk,
398
			     (skb_shinfo(skb)->gso_segs ?: 1) - 1);
L
Linus Torvalds 已提交
399 400

	skb->priority = sk->sk_priority;
401
	skb->mark = sk->sk_mark;
L
Linus Torvalds 已提交
402

403 404 405
	res = ip_local_out(skb);
	rcu_read_unlock();
	return res;
L
Linus Torvalds 已提交
406 407

no_route:
408
	rcu_read_unlock();
P
Pavel Emelyanov 已提交
409
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
L
Linus Torvalds 已提交
410 411 412
	kfree_skb(skb);
	return -EHOSTUNREACH;
}
E
Eric Dumazet 已提交
413
EXPORT_SYMBOL(ip_queue_xmit);
L
Linus Torvalds 已提交
414 415 416 417 418 419 420


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;
E
Eric Dumazet 已提交
421
	skb_dst_drop(to);
422
	skb_dst_copy(to, from);
L
Linus Torvalds 已提交
423
	to->dev = from->dev;
T
Thomas Graf 已提交
424
	to->mark = from->mark;
L
Linus Torvalds 已提交
425 426 427 428 429 430 431

	/* Copy the flags to each fragment. */
	IPCB(to)->flags = IPCB(from)->flags;

#ifdef CONFIG_NET_SCHED
	to->tc_index = from->tc_index;
#endif
432
	nf_copy(to, from);
433 434 435 436
#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
	to->nf_trace = from->nf_trace;
#endif
437 438
#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
	to->ipvs_property = from->ipvs_property;
L
Linus Torvalds 已提交
439
#endif
440
	skb_copy_secmark(to, from);
L
Linus Torvalds 已提交
441 442 443 444 445 446 447 448 449
}

/*
 *	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.
 */

450
int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
L
Linus Torvalds 已提交
451 452 453 454 455
{
	struct iphdr *iph;
	int ptr;
	struct net_device *dev;
	struct sk_buff *skb2;
456
	unsigned int mtu, hlen, left, len, ll_rs;
L
Linus Torvalds 已提交
457
	int offset;
458
	__be16 not_last_frag;
E
Eric Dumazet 已提交
459
	struct rtable *rt = skb_rtable(skb);
L
Linus Torvalds 已提交
460 461
	int err = 0;

462
	dev = rt->dst.dev;
L
Linus Torvalds 已提交
463 464 465 466 467

	/*
	 *	Point into the IP datagram header.
	 */

468
	iph = ip_hdr(skb);
L
Linus Torvalds 已提交
469

470 471 472
	if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
		     (IPCB(skb)->frag_max_size &&
		      IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) {
P
Pavel Emelyanov 已提交
473
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
474
		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
J
John Heffner 已提交
475
			  htonl(ip_skb_dst_mtu(skb)));
L
Linus Torvalds 已提交
476 477 478 479 480 481 482 483 484
		kfree_skb(skb);
		return -EMSGSIZE;
	}

	/*
	 *	Setup starting values.
	 */

	hlen = iph->ihl * 4;
485
	mtu = dst_mtu(&rt->dst) - hlen;	/* Size of data space */
486 487 488 489
#ifdef CONFIG_BRIDGE_NETFILTER
	if (skb->nf_bridge)
		mtu -= nf_bridge_mtu_reduction(skb);
#endif
H
Herbert Xu 已提交
490
	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
L
Linus Torvalds 已提交
491 492 493 494 495 496 497 498

	/* 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.
	 */
499
	if (skb_has_frag_list(skb)) {
500
		struct sk_buff *frag, *frag2;
L
Linus Torvalds 已提交
501 502 503 504
		int first_len = skb_pagelen(skb);

		if (first_len - hlen > mtu ||
		    ((first_len - hlen) & 7) ||
505
		    ip_is_fragment(iph) ||
L
Linus Torvalds 已提交
506 507 508
		    skb_cloned(skb))
			goto slow_path;

509
		skb_walk_frags(skb, frag) {
L
Linus Torvalds 已提交
510 511 512 513
			/* Correct geometry. */
			if (frag->len > mtu ||
			    ((frag->len & 7) && frag->next) ||
			    skb_headroom(frag) < hlen)
514
				goto slow_path_clean;
L
Linus Torvalds 已提交
515 516 517

			/* Partially cloned skb? */
			if (skb_shared(frag))
518
				goto slow_path_clean;
519 520 521 522 523 524

			BUG_ON(frag->sk);
			if (skb->sk) {
				frag->sk = skb->sk;
				frag->destructor = sock_wfree;
			}
525
			skb->truesize -= frag->truesize;
L
Linus Torvalds 已提交
526 527 528 529 530 531 532
		}

		/* Everything is OK. Generate! */

		err = 0;
		offset = 0;
		frag = skb_shinfo(skb)->frag_list;
533
		skb_frag_list_init(skb);
L
Linus Torvalds 已提交
534 535 536 537 538 539 540 541 542 543 544
		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;
545
				skb_reset_transport_header(frag);
546 547
				__skb_push(frag, hlen);
				skb_reset_network_header(frag);
548
				memcpy(skb_network_header(frag), iph, hlen);
549
				iph = ip_hdr(frag);
L
Linus Torvalds 已提交
550 551 552 553 554 555 556 557 558 559 560 561 562 563
				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);

564
			if (!err)
P
Pavel Emelyanov 已提交
565
				IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
566 567 568 569 570 571 572 573 574
			if (err || !frag)
				break;

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

		if (err == 0) {
P
Pavel Emelyanov 已提交
575
			IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
576 577 578 579 580 581 582 583
			return 0;
		}

		while (frag) {
			skb = frag->next;
			kfree_skb(frag);
			frag = skb;
		}
P
Pavel Emelyanov 已提交
584
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
585
		return err;
586 587 588 589 590 591 592 593 594

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
595 596 597
	}

slow_path:
598 599 600 601
	/* for offloaded checksums cleanup checksum before fragmentation */
	if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
		goto fail;

L
Linus Torvalds 已提交
602
	left = skb->len - hlen;		/* Space per frame */
603
	ptr = hlen;		/* Where to start from */
L
Linus Torvalds 已提交
604 605

	/* for bridged IP traffic encapsulated inside f.e. a vlan header,
606 607
	 * we need to make room for the encapsulating header
	 */
608
	ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
609

L
Linus Torvalds 已提交
610 611 612 613 614 615 616 617 618 619 620
	/*
	 *	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
621
	while (left > 0) {
L
Linus Torvalds 已提交
622 623 624 625
		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
626
		/* IF: we are not sending up to and including the packet end
L
Linus Torvalds 已提交
627 628 629 630 631 632 633 634 635
		   then align the next start on an eight byte boundary */
		if (len < left)	{
			len &= ~7;
		}
		/*
		 *	Allocate buffer.
		 */

		if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
636
			NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
L
Linus Torvalds 已提交
637 638 639 640 641 642 643 644 645 646 647
			err = -ENOMEM;
			goto fail;
		}

		/*
		 *	Set up data on packet
		 */

		ip_copy_metadata(skb2, skb);
		skb_reserve(skb2, ll_rs);
		skb_put(skb2, len + hlen);
648
		skb_reset_network_header(skb2);
649
		skb2->transport_header = skb2->network_header + hlen;
L
Linus Torvalds 已提交
650 651 652 653 654 655 656 657 658 659 660 661 662

		/*
		 *	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.
		 */

663
		skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
L
Linus Torvalds 已提交
664 665 666 667

		/*
		 *	Copy a block of the IP datagram.
		 */
668
		if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
L
Linus Torvalds 已提交
669 670 671 672 673 674
			BUG();
		left -= len;

		/*
		 *	Fill in the new header fields.
		 */
675
		iph = ip_hdr(skb2);
L
Linus Torvalds 已提交
676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705
		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;
706

P
Pavel Emelyanov 已提交
707
		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
L
Linus Torvalds 已提交
708
	}
709
	consume_skb(skb);
P
Pavel Emelyanov 已提交
710
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
L
Linus Torvalds 已提交
711 712 713
	return err;

fail:
714
	kfree_skb(skb);
P
Pavel Emelyanov 已提交
715
	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
L
Linus Torvalds 已提交
716 717
	return err;
}
718 719
EXPORT_SYMBOL(ip_fragment);

L
Linus Torvalds 已提交
720 721 722 723 724
int
ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
	struct iovec *iov = from;

725
	if (skb->ip_summed == CHECKSUM_PARTIAL) {
L
Linus Torvalds 已提交
726 727 728
		if (memcpy_fromiovecend(to, iov, offset, len) < 0)
			return -EFAULT;
	} else {
729
		__wsum csum = 0;
L
Linus Torvalds 已提交
730 731 732 733 734 735
		if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
			return -EFAULT;
		skb->csum = csum_block_add(skb->csum, csum, odd);
	}
	return 0;
}
E
Eric Dumazet 已提交
736
EXPORT_SYMBOL(ip_generic_getfrag);
L
Linus Torvalds 已提交
737

738
static inline __wsum
L
Linus Torvalds 已提交
739 740 741
csum_page(struct page *page, int offset, int copy)
{
	char *kaddr;
742
	__wsum csum;
L
Linus Torvalds 已提交
743 744 745 746 747 748
	kaddr = kmap(page);
	csum = csum_partial(kaddr + offset, copy, 0);
	kunmap(page);
	return csum;
}

A
Adrian Bunk 已提交
749
static inline int ip_ufo_append_data(struct sock *sk,
750
			struct sk_buff_head *queue,
751 752 753
			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,
754
			int transhdrlen, int maxfraglen, unsigned int flags)
755 756 757 758 759 760 761 762
{
	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
	 */
763
	if ((skb = skb_peek_tail(queue)) == NULL) {
764 765 766 767 768 769 770 771 772 773 774
		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 */
775
		skb_put(skb, fragheaderlen + transhdrlen);
776 777

		/* initialize network header pointer */
778
		skb_reset_network_header(skb);
779 780

		/* initialize protocol header pointer */
781
		skb->transport_header = skb->network_header + fragheaderlen;
782

783
		skb->ip_summed = CHECKSUM_PARTIAL;
784 785
		skb->csum = 0;

786
		/* specify the length of each IP datagram fragment */
787
		skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
H
Herbert Xu 已提交
788
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
789
		__skb_queue_tail(queue, skb);
790
	}
791 792 793

	return skb_append_datato_frags(sk, skb, getfrag, from,
				       (length - transhdrlen));
794 795
}

796 797 798
static int __ip_append_data(struct sock *sk,
			    struct flowi4 *fl4,
			    struct sk_buff_head *queue,
799
			    struct inet_cork *cork,
800
			    struct page_frag *pfrag,
801 802 803 804
			    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
805 806 807 808
{
	struct inet_sock *inet = inet_sk(sk);
	struct sk_buff *skb;

809
	struct ip_options *opt = cork->opt;
L
Linus Torvalds 已提交
810 811 812 813 814 815 816 817
	int hh_len;
	int exthdrlen;
	int mtu;
	int copy;
	int err;
	int offset = 0;
	unsigned int maxfraglen, fragheaderlen;
	int csummode = CHECKSUM_NONE;
818
	struct rtable *rt = (struct rtable *)cork->dst;
L
Linus Torvalds 已提交
819

820 821 822
	skb = skb_peek_tail(queue);

	exthdrlen = !skb ? rt->dst.header_len : 0;
823
	mtu = cork->fragsize;
L
Linus Torvalds 已提交
824

825
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
L
Linus Torvalds 已提交
826 827 828 829

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

830
	if (cork->length + length > 0xFFFF - fragheaderlen) {
831
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
E
Eric Dumazet 已提交
832
			       mtu-exthdrlen);
L
Linus Torvalds 已提交
833 834 835 836 837 838 839 840 841
		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 &&
842
	    rt->dst.dev->features & NETIF_F_V4_CSUM &&
L
Linus Torvalds 已提交
843
	    !exthdrlen)
844
		csummode = CHECKSUM_PARTIAL;
L
Linus Torvalds 已提交
845

846
	cork->length += length;
847
	if (((length > mtu) || (skb && skb_is_gso(skb))) &&
848
	    (sk->sk_protocol == IPPROTO_UDP) &&
849
	    (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
850 851
		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
					 hh_len, fragheaderlen, transhdrlen,
852
					 maxfraglen, flags);
853
		if (err)
854 855 856
			goto error;
		return 0;
	}
L
Linus Torvalds 已提交
857 858 859 860 861 862 863 864

	/* 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.
	 */

865
	if (!skb)
L
Linus Torvalds 已提交
866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895
		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;

896
			if ((flags & MSG_MORE) &&
897
			    !(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
898 899
				alloclen = mtu;
			else
900
				alloclen = fraglen;
L
Linus Torvalds 已提交
901

902 903
			alloclen += exthdrlen;

L
Linus Torvalds 已提交
904 905 906 907 908
			/* 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.
			 */
909
			if (datalen == length + fraggap)
910
				alloclen += rt->dst.trailer_len;
911

L
Linus Torvalds 已提交
912
			if (transhdrlen) {
913
				skb = sock_alloc_send_skb(sk,
L
Linus Torvalds 已提交
914 915 916 917 918 919
						alloclen + hh_len + 15,
						(flags & MSG_DONTWAIT), &err);
			} else {
				skb = NULL;
				if (atomic_read(&sk->sk_wmem_alloc) <=
				    2 * sk->sk_sndbuf)
920
					skb = sock_wmalloc(sk,
L
Linus Torvalds 已提交
921 922 923 924
							   alloclen + hh_len + 15, 1,
							   sk->sk_allocation);
				if (unlikely(skb == NULL))
					err = -ENOBUFS;
925 926 927
				else
					/* only the initial fragment is
					   time stamped */
928
					cork->tx_flags = 0;
L
Linus Torvalds 已提交
929 930 931 932 933 934 935 936 937 938
			}
			if (skb == NULL)
				goto error;

			/*
			 *	Fill in the control structures
			 */
			skb->ip_summed = csummode;
			skb->csum = 0;
			skb_reserve(skb, hh_len);
939
			skb_shinfo(skb)->tx_flags = cork->tx_flags;
L
Linus Torvalds 已提交
940 941 942 943

			/*
			 *	Find where to start putting bytes.
			 */
944
			data = skb_put(skb, fraglen + exthdrlen);
945
			skb_set_network_header(skb, exthdrlen);
946 947
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
948
			data += fragheaderlen + exthdrlen;
L
Linus Torvalds 已提交
949 950 951 952 953 954 955 956

			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;
957
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975
			}

			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.
			 */
976
			__skb_queue_tail(queue, skb);
L
Linus Torvalds 已提交
977 978 979 980 981 982
			continue;
		}

		if (copy > length)
			copy = length;

983
		if (!(rt->dst.dev->features&NETIF_F_SG)) {
L
Linus Torvalds 已提交
984 985 986
			unsigned int off;

			off = skb->len;
987
			if (getfrag(from, skb_put(skb, copy),
L
Linus Torvalds 已提交
988 989 990 991 992 993 994 995
					offset, copy, off, skb) < 0) {
				__skb_trim(skb, off);
				err = -EFAULT;
				goto error;
			}
		} else {
			int i = skb_shinfo(skb)->nr_frags;

996 997
			err = -ENOMEM;
			if (!sk_page_frag_refill(sk, pfrag))
L
Linus Torvalds 已提交
998
				goto error;
999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009

			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
1010
			}
1011 1012 1013 1014 1015 1016 1017 1018
			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
1019 1020
			skb->len += copy;
			skb->data_len += copy;
1021 1022
			skb->truesize += copy;
			atomic_add(copy, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1023 1024 1025 1026 1027 1028 1029
		}
		offset += copy;
		length -= copy;
	}

	return 0;

1030 1031
error_efault:
	err = -EFAULT;
L
Linus Torvalds 已提交
1032
error:
1033
	cork->length -= length;
P
Pavel Emelyanov 已提交
1034
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1035
	return err;
L
Linus Torvalds 已提交
1036 1037
}

1038 1039 1040 1041
static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
			 struct ipcm_cookie *ipc, struct rtable **rtp)
{
	struct inet_sock *inet = inet_sk(sk);
1042
	struct ip_options_rcu *opt;
1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
	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;
		}
1056
		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067
		cork->flags |= IPCORK_OPT;
		cork->addr = ipc->addr;
	}
	rt = *rtp;
	if (unlikely(!rt))
		return -EFAULT;
	/*
	 * We steal reference to this route, caller should not release it
	 */
	*rtp = NULL;
	cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1068
			 rt->dst.dev->mtu : dst_mtu(&rt->dst);
1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086
	cork->dst = &rt->dst;
	cork->length = 0;
	cork->tx_flags = ipc->tx_flags;

	return 0;
}

/*
 *	ip_append_data() and ip_append_page() can make one large IP datagram
 *	from many pieces of data. Each pieces will be holded on the socket
 *	until ip_push_pending_frames() is called. Each piece can be a page
 *	or non-page data.
 *
 *	Not only UDP, other transport protocols - e.g. raw sockets - can use
 *	this interface potentially.
 *
 *	LATER: length must be adjusted by pad at tail, when it is required.
 */
1087
int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
		   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)) {
1101
		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1102 1103 1104 1105 1106 1107
		if (err)
			return err;
	} else {
		transhdrlen = 0;
	}

1108 1109
	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
				sk_page_frag(sk), getfrag,
1110 1111 1112
				from, length, transhdrlen, flags);
}

1113
ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
L
Linus Torvalds 已提交
1114 1115 1116 1117 1118 1119
		       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;
1120
	struct inet_cork *cork;
L
Linus Torvalds 已提交
1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135
	int hh_len;
	int mtu;
	int len;
	int err;
	unsigned int maxfraglen, fragheaderlen, fraggap;

	if (inet->hdrincl)
		return -EPERM;

	if (flags&MSG_PROBE)
		return 0;

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

1136 1137 1138 1139
	cork = &inet->cork.base;
	rt = (struct rtable *)cork->dst;
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1140

1141
	if (!(rt->dst.dev->features&NETIF_F_SG))
L
Linus Torvalds 已提交
1142 1143
		return -EOPNOTSUPP;

1144
	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1145
	mtu = cork->fragsize;
L
Linus Torvalds 已提交
1146 1147 1148 1149

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

1150
	if (cork->length + size > 0xFFFF - fragheaderlen) {
1151
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
L
Linus Torvalds 已提交
1152 1153 1154 1155 1156 1157
		return -EMSGSIZE;
	}

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

1158
	cork->length += size;
1159 1160
	if ((size + skb->len > mtu) &&
	    (sk->sk_protocol == IPPROTO_UDP) &&
1161
	    (rt->dst.dev->features & NETIF_F_UFO)) {
1162
		skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
H
Herbert Xu 已提交
1163
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1164
	}
1165

L
Linus Torvalds 已提交
1166 1167 1168 1169

	while (size > 0) {
		int i;

H
Herbert Xu 已提交
1170
		if (skb_is_gso(skb))
1171 1172 1173 1174 1175 1176 1177 1178
			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
1179 1180 1181 1182 1183
		if (len <= 0) {
			struct sk_buff *skb_prev;
			int alloclen;

			skb_prev = skb;
1184
			fraggap = skb_prev->len - maxfraglen;
L
Linus Torvalds 已提交
1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202

			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.
			 */
1203
			skb_put(skb, fragheaderlen + fraggap);
1204
			skb_reset_network_header(skb);
1205 1206
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
L
Linus Torvalds 已提交
1207
			if (fraggap) {
1208 1209
				skb->csum = skb_copy_and_csum_bits(skb_prev,
								   maxfraglen,
1210
						    skb_transport_header(skb),
1211
								   fraggap, 0);
L
Linus Torvalds 已提交
1212 1213
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
1214
				pskb_trim_unique(skb_prev, maxfraglen);
L
Linus Torvalds 已提交
1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227
			}

			/*
			 * 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
1228
			skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
L
Linus Torvalds 已提交
1229 1230 1231 1232 1233 1234 1235 1236 1237
		} 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) {
1238
			__wsum csum;
L
Linus Torvalds 已提交
1239 1240 1241 1242 1243 1244
			csum = csum_page(page, offset, len);
			skb->csum = csum_block_add(skb->csum, csum, skb->len);
		}

		skb->len += len;
		skb->data_len += len;
1245 1246
		skb->truesize += len;
		atomic_add(len, &sk->sk_wmem_alloc);
L
Linus Torvalds 已提交
1247 1248 1249 1250 1251 1252
		offset += len;
		size -= len;
	}
	return 0;

error:
1253
	cork->length -= size;
P
Pavel Emelyanov 已提交
1254
	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1255 1256 1257
	return err;
}

1258
static void ip_cork_release(struct inet_cork *cork)
1259
{
1260 1261 1262 1263 1264
	cork->flags &= ~IPCORK_OPT;
	kfree(cork->opt);
	cork->opt = NULL;
	dst_release(cork->dst);
	cork->dst = NULL;
1265 1266
}

L
Linus Torvalds 已提交
1267 1268 1269 1270
/*
 *	Combined all pending IP fragments on the socket as one IP datagram
 *	and push them out.
 */
1271
struct sk_buff *__ip_make_skb(struct sock *sk,
1272
			      struct flowi4 *fl4,
1273 1274
			      struct sk_buff_head *queue,
			      struct inet_cork *cork)
L
Linus Torvalds 已提交
1275 1276 1277 1278
{
	struct sk_buff *skb, *tmp_skb;
	struct sk_buff **tail_skb;
	struct inet_sock *inet = inet_sk(sk);
1279
	struct net *net = sock_net(sk);
L
Linus Torvalds 已提交
1280
	struct ip_options *opt = NULL;
1281
	struct rtable *rt = (struct rtable *)cork->dst;
L
Linus Torvalds 已提交
1282
	struct iphdr *iph;
1283
	__be16 df = 0;
L
Linus Torvalds 已提交
1284 1285
	__u8 ttl;

1286
	if ((skb = __skb_dequeue(queue)) == NULL)
L
Linus Torvalds 已提交
1287 1288 1289 1290
		goto out;
	tail_skb = &(skb_shinfo(skb)->frag_list);

	/* move skb->data to ip header from ext header */
1291
	if (skb->data < skb_network_header(skb))
1292
		__skb_pull(skb, skb_network_offset(skb));
1293
	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1294
		__skb_pull(tmp_skb, skb_network_header_len(skb));
L
Linus Torvalds 已提交
1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307
		*tail_skb = tmp_skb;
		tail_skb = &(tmp_skb->next);
		skb->len += tmp_skb->len;
		skb->data_len += tmp_skb->len;
		skb->truesize += tmp_skb->truesize;
		tmp_skb->destructor = NULL;
		tmp_skb->sk = NULL;
	}

	/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
	 * to fragment the frame generated here. No matter, what transforms
	 * how transforms change size of the packet, it will come out.
	 */
J
John Heffner 已提交
1308
	if (inet->pmtudisc < IP_PMTUDISC_DO)
L
Linus Torvalds 已提交
1309 1310 1311 1312 1313
		skb->local_df = 1;

	/* DF bit is set when we want to see DF on outgoing frames.
	 * If local_df is set too, we still allow to fragment this frame
	 * locally. */
J
John Heffner 已提交
1314
	if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1315 1316
	    (skb->len <= dst_mtu(&rt->dst) &&
	     ip_dont_fragment(sk, &rt->dst)))
L
Linus Torvalds 已提交
1317 1318
		df = htons(IP_DF);

1319 1320
	if (cork->flags & IPCORK_OPT)
		opt = cork->opt;
L
Linus Torvalds 已提交
1321 1322 1323 1324

	if (rt->rt_type == RTN_MULTICAST)
		ttl = inet->mc_ttl;
	else
1325
		ttl = ip_select_ttl(inet, &rt->dst);
L
Linus Torvalds 已提交
1326 1327 1328 1329 1330 1331 1332 1333

	iph = (struct iphdr *)skb->data;
	iph->version = 4;
	iph->ihl = 5;
	iph->tos = inet->tos;
	iph->frag_off = df;
	iph->ttl = ttl;
	iph->protocol = sk->sk_protocol;
1334
	ip_copy_addrs(iph, fl4);
1335
	ip_select_ident(iph, &rt->dst, sk);
L
Linus Torvalds 已提交
1336

1337 1338 1339 1340 1341
	if (opt) {
		iph->ihl += opt->optlen>>2;
		ip_options_build(skb, opt, cork->addr, rt, 0);
	}

L
Linus Torvalds 已提交
1342
	skb->priority = sk->sk_priority;
1343
	skb->mark = sk->sk_mark;
1344 1345 1346 1347
	/*
	 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
	 * on dst refcount
	 */
1348
	cork->dst = NULL;
1349
	skb_dst_set(skb, &rt->dst);
L
Linus Torvalds 已提交
1350

1351
	if (iph->protocol == IPPROTO_ICMP)
1352
		icmp_out_count(net, ((struct icmphdr *)
1353 1354
			skb_transport_header(skb))->type);

1355 1356 1357 1358 1359
	ip_cork_release(cork);
out:
	return skb;
}

E
Eric Dumazet 已提交
1360
int ip_send_skb(struct net *net, struct sk_buff *skb)
1361 1362 1363
{
	int err;

H
Herbert Xu 已提交
1364
	err = ip_local_out(skb);
L
Linus Torvalds 已提交
1365 1366
	if (err) {
		if (err > 0)
E
Eric Dumazet 已提交
1367
			err = net_xmit_errno(err);
L
Linus Torvalds 已提交
1368
		if (err)
1369
			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
L
Linus Torvalds 已提交
1370 1371 1372 1373 1374
	}

	return err;
}

1375
int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1376
{
1377 1378
	struct sk_buff *skb;

1379
	skb = ip_finish_skb(sk, fl4);
1380 1381 1382 1383
	if (!skb)
		return 0;

	/* Netfilter gets whole the not fragmented skb. */
E
Eric Dumazet 已提交
1384
	return ip_send_skb(sock_net(sk), skb);
1385 1386
}

L
Linus Torvalds 已提交
1387 1388 1389
/*
 *	Throw away all pending data on the socket.
 */
1390 1391 1392
static void __ip_flush_pending_frames(struct sock *sk,
				      struct sk_buff_head *queue,
				      struct inet_cork *cork)
L
Linus Torvalds 已提交
1393 1394 1395
{
	struct sk_buff *skb;

1396
	while ((skb = __skb_dequeue_tail(queue)) != NULL)
L
Linus Torvalds 已提交
1397 1398
		kfree_skb(skb);

1399 1400 1401 1402 1403
	ip_cork_release(cork);
}

void ip_flush_pending_frames(struct sock *sk)
{
1404
	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
L
Linus Torvalds 已提交
1405 1406
}

1407
struct sk_buff *ip_make_skb(struct sock *sk,
1408
			    struct flowi4 *fl4,
1409 1410 1411 1412 1413 1414
			    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)
{
1415
	struct inet_cork cork;
1416 1417 1418 1419 1420 1421 1422 1423
	struct sk_buff_head queue;
	int err;

	if (flags & MSG_PROBE)
		return NULL;

	__skb_queue_head_init(&queue);

1424 1425
	cork.flags = 0;
	cork.addr = 0;
1426
	cork.opt = NULL;
1427 1428 1429 1430
	err = ip_setup_cork(sk, &cork, ipc, rtp);
	if (err)
		return ERR_PTR(err);

1431 1432
	err = __ip_append_data(sk, fl4, &queue, &cork,
			       &current->task_frag, getfrag,
1433 1434 1435 1436 1437 1438
			       from, length, transhdrlen, flags);
	if (err) {
		__ip_flush_pending_frames(sk, &queue, &cork);
		return ERR_PTR(err);
	}

1439
	return __ip_make_skb(sk, fl4, &queue, &cork);
1440
}
L
Linus Torvalds 已提交
1441 1442 1443 1444

/*
 *	Fetch data from kernel space and fill in checksum if needed.
 */
1445
static int ip_reply_glue_bits(void *dptr, char *to, int offset,
L
Linus Torvalds 已提交
1446 1447
			      int len, int odd, struct sk_buff *skb)
{
1448
	__wsum csum;
L
Linus Torvalds 已提交
1449 1450 1451

	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
	skb->csum = csum_block_add(skb->csum, csum, odd);
1452
	return 0;
L
Linus Torvalds 已提交
1453 1454
}

1455
/*
L
Linus Torvalds 已提交
1456
 *	Generic function to send a packet as reply to another packet.
1457
 *	Used to send some TCP resets/acks so far.
L
Linus Torvalds 已提交
1458
 *
1459
 *	Use a fake percpu inet socket to avoid false sharing and contention.
L
Linus Torvalds 已提交
1460
 */
1461 1462 1463 1464 1465 1466 1467 1468 1469
static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
	.sk = {
		.__sk_common = {
			.skc_refcnt = ATOMIC_INIT(1),
		},
		.sk_wmem_alloc	= ATOMIC_INIT(1),
		.sk_allocation	= GFP_ATOMIC,
		.sk_flags	= (1UL << SOCK_USE_WRITE_QUEUE),
	},
1470 1471
	.pmtudisc	= IP_PMTUDISC_WANT,
	.uc_ttl		= -1,
1472 1473 1474
};

void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
1475 1476
			   __be32 saddr, const struct ip_reply_arg *arg,
			   unsigned int len)
L
Linus Torvalds 已提交
1477
{
1478
	struct ip_options_data replyopts;
L
Linus Torvalds 已提交
1479
	struct ipcm_cookie ipc;
1480
	struct flowi4 fl4;
E
Eric Dumazet 已提交
1481
	struct rtable *rt = skb_rtable(skb);
1482 1483 1484
	struct sk_buff *nskb;
	struct sock *sk;
	struct inet_sock *inet;
L
Linus Torvalds 已提交
1485

1486
	if (ip_options_echo(&replyopts.opt.opt, skb))
L
Linus Torvalds 已提交
1487 1488
		return;

1489
	ipc.addr = daddr;
L
Linus Torvalds 已提交
1490
	ipc.opt = NULL;
1491
	ipc.tx_flags = 0;
L
Linus Torvalds 已提交
1492

1493
	if (replyopts.opt.opt.optlen) {
L
Linus Torvalds 已提交
1494 1495
		ipc.opt = &replyopts.opt;

1496 1497
		if (replyopts.opt.opt.srr)
			daddr = replyopts.opt.opt.faddr;
L
Linus Torvalds 已提交
1498 1499
	}

1500
	flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1501
			   RT_TOS(arg->tos),
1502
			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1503
			   ip_reply_arg_flowi_flags(arg),
1504
			   daddr, saddr,
1505 1506
			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1507
	rt = ip_route_output_key(net, &fl4);
1508 1509
	if (IS_ERR(rt))
		return;
L
Linus Torvalds 已提交
1510

1511
	inet = &get_cpu_var(unicast_sock);
L
Linus Torvalds 已提交
1512

1513
	inet->tos = arg->tos;
1514
	sk = &inet->sk;
L
Linus Torvalds 已提交
1515
	sk->sk_priority = skb->priority;
1516
	sk->sk_protocol = ip_hdr(skb)->protocol;
1517
	sk->sk_bound_dev_if = arg->bound_dev_if;
1518 1519 1520
	sock_net_set(sk, net);
	__skb_queue_head_init(&sk->sk_write_queue);
	sk->sk_sndbuf = sysctl_wmem_default;
1521
	ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1522
		       &ipc, &rt, MSG_DONTWAIT);
1523 1524
	nskb = skb_peek(&sk->sk_write_queue);
	if (nskb) {
L
Linus Torvalds 已提交
1525
		if (arg->csumoffset >= 0)
1526 1527
			*((__sum16 *)skb_transport_header(nskb) +
			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1528
								arg->csum));
1529
		nskb->ip_summed = CHECKSUM_NONE;
1530
		skb_orphan(nskb);
1531
		skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1532
		ip_push_pending_frames(sk, &fl4);
L
Linus Torvalds 已提交
1533 1534
	}

1535
	put_cpu_var(unicast_sock);
L
Linus Torvalds 已提交
1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548

	ip_rt_put(rt);
}

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

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