1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * The Internet Protocol (IP) output module.
7 *
8 * Authors: Ross Biro
9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
11 * Alan Cox, <Alan.Cox@linux.org>
12 * Richard Underwood
13 * Stefan Becker, <stefanb@yello.ping.de>
14 * Jorge Cwik, <jorge@laser.satlink.net>
15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
16 * Hirokazu Takahashi, <taka@valinux.co.jp>
17 *
18 * See ip_input.c for original log
19 *
20 * Fixes:
21 * Alan Cox : Missing nonblock feature in ip_build_xmit.
22 * Mike Kilburn : htons() missing in ip_build_xmit.
23 * Bradford Johnson: Fix faulty handling of some frames when
24 * no route is found.
25 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
26 * (in case if packet not accepted by
27 * output firewall rules)
28 * Mike McLagan : Routing by source
29 * Alexey Kuznetsov: use new route cache
30 * Andi Kleen: Fix broken PMTU recovery and remove
31 * some redundant tests.
32 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
33 * Andi Kleen : Replace ip_reply with ip_send_reply.
34 * Andi Kleen : Split fast and slow ip_build_xmit path
35 * for decreased register pressure on x86
36 * and more readibility.
37 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
38 * silently drop skb instead of failing with -EPERM.
39 * Detlev Wengorz : Copy protocol for fragments.
40 * Hirokazu Takahashi: HW checksumming for outgoing UDP
41 * datagrams.
42 * Hirokazu Takahashi: sendfile() on UDP works now.
43 */
44
45#include <linux/uaccess.h>
46#include <linux/module.h>
47#include <linux/types.h>
48#include <linux/kernel.h>
49#include <linux/mm.h>
50#include <linux/string.h>
51#include <linux/errno.h>
52#include <linux/highmem.h>
53#include <linux/slab.h>
54
55#include <linux/socket.h>
56#include <linux/sockios.h>
57#include <linux/in.h>
58#include <linux/inet.h>
59#include <linux/netdevice.h>
60#include <linux/etherdevice.h>
61#include <linux/proc_fs.h>
62#include <linux/stat.h>
63#include <linux/init.h>
64
65#include <net/snmp.h>
66#include <net/ip.h>
67#include <net/protocol.h>
68#include <net/route.h>
69#include <net/xfrm.h>
70#include <linux/skbuff.h>
71#include <net/sock.h>
72#include <net/arp.h>
73#include <net/icmp.h>
74#include <net/checksum.h>
75#include <net/inetpeer.h>
76#include <net/lwtunnel.h>
77#include <linux/bpf-cgroup.h>
78#include <linux/igmp.h>
79#include <linux/netfilter_ipv4.h>
80#include <linux/netfilter_bridge.h>
81#include <linux/netlink.h>
82#include <linux/tcp.h>
83
84static int
85ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
86 unsigned int mtu,
87 int (*output)(struct net *, struct sock *, struct sk_buff *));
88
89/* Generate a checksum for an outgoing IP datagram. */
90void ip_send_check(struct iphdr *iph)
91{
92 iph->check = 0;
93 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
94}
95EXPORT_SYMBOL(ip_send_check);
96
97int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
98{
99 struct iphdr *iph = ip_hdr(skb);
100
101 iph->tot_len = htons(skb->len);
102 ip_send_check(iph);
103
104 /* if egress device is enslaved to an L3 master device pass the
105 * skb to its handler for processing
106 */
107 skb = l3mdev_ip_out(sk, skb);
108 if (unlikely(!skb))
109 return 0;
110
111 skb->protocol = htons(ETH_P_IP);
112
113 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
114 net, sk, skb, NULL, skb_dst(skb)->dev,
115 dst_output);
116}
117
118int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
119{
120 int err;
121
122 err = __ip_local_out(net, sk, skb);
123 if (likely(err == 1))
124 err = dst_output(net, sk, skb);
125
126 return err;
127}
128EXPORT_SYMBOL_GPL(ip_local_out);
129
130static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
131{
132 int ttl = inet->uc_ttl;
133
134 if (ttl < 0)
135 ttl = ip4_dst_hoplimit(dst);
136 return ttl;
137}
138
139/*
140 * Add an ip header to a skbuff and send it out.
141 *
142 */
143int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
144 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
145{
146 struct inet_sock *inet = inet_sk(sk);
147 struct rtable *rt = skb_rtable(skb);
148 struct net *net = sock_net(sk);
149 struct iphdr *iph;
150
151 /* Build the IP header. */
152 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
153 skb_reset_network_header(skb);
154 iph = ip_hdr(skb);
155 iph->version = 4;
156 iph->ihl = 5;
157 iph->tos = inet->tos;
158 iph->ttl = ip_select_ttl(inet, &rt->dst);
159 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
160 iph->saddr = saddr;
161 iph->protocol = sk->sk_protocol;
162 if (ip_dont_fragment(sk, &rt->dst)) {
163 iph->frag_off = htons(IP_DF);
164 iph->id = 0;
165 } else {
166 iph->frag_off = 0;
167 __ip_select_ident(net, iph, 1);
168 }
169
170 if (opt && opt->opt.optlen) {
171 iph->ihl += opt->opt.optlen>>2;
172 ip_options_build(skb, &opt->opt, daddr, rt, 0);
173 }
174
175 skb->priority = sk->sk_priority;
176 if (!skb->mark)
177 skb->mark = sk->sk_mark;
178
179 /* Send it out. */
180 return ip_local_out(net, skb->sk, skb);
181}
182EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
183
184static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
185{
186 struct dst_entry *dst = skb_dst(skb);
187 struct rtable *rt = (struct rtable *)dst;
188 struct net_device *dev = dst->dev;
189 unsigned int hh_len = LL_RESERVED_SPACE(dev);
190 struct neighbour *neigh;
191 u32 nexthop;
192
193 if (rt->rt_type == RTN_MULTICAST) {
194 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
195 } else if (rt->rt_type == RTN_BROADCAST)
196 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
197
198 /* Be paranoid, rather than too clever. */
199 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
200 struct sk_buff *skb2;
201
202 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
203 if (!skb2) {
204 kfree_skb(skb);
205 return -ENOMEM;
206 }
207 if (skb->sk)
208 skb_set_owner_w(skb2, skb->sk);
209 consume_skb(skb);
210 skb = skb2;
211 }
212
213 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
214 int res = lwtunnel_xmit(skb);
215
216 if (res < 0 || res == LWTUNNEL_XMIT_DONE)
217 return res;
218 }
219
220 rcu_read_lock_bh();
221 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
222 neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
223 if (unlikely(!neigh))
224 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
225 if (!IS_ERR(neigh)) {
226 int res;
227
228 sock_confirm_neigh(skb, neigh);
229 res = neigh_output(neigh, skb);
230
231 rcu_read_unlock_bh();
232 return res;
233 }
234 rcu_read_unlock_bh();
235
236 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
237 __func__);
238 kfree_skb(skb);
239 return -EINVAL;
240}
241
242static int ip_finish_output_gso(struct net *net, struct sock *sk,
243 struct sk_buff *skb, unsigned int mtu)
244{
245 netdev_features_t features;
246 struct sk_buff *segs;
247 int ret = 0;
248
249 /* common case: seglen is <= mtu
250 */
251 if (skb_gso_validate_network_len(skb, mtu))
252 return ip_finish_output2(net, sk, skb);
253
254 /* Slowpath - GSO segment length exceeds the egress MTU.
255 *
256 * This can happen in several cases:
257 * - Forwarding of a TCP GRO skb, when DF flag is not set.
258 * - Forwarding of an skb that arrived on a virtualization interface
259 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
260 * stack.
261 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
262 * interface with a smaller MTU.
263 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
264 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
265 * insufficent MTU.
266 */
267 features = netif_skb_features(skb);
268 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
269 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
270 if (IS_ERR_OR_NULL(segs)) {
271 kfree_skb(skb);
272 return -ENOMEM;
273 }
274
275 consume_skb(skb);
276
277 do {
278 struct sk_buff *nskb = segs->next;
279 int err;
280
281 skb_mark_not_on_list(segs);
282 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
283
284 if (err && ret == 0)
285 ret = err;
286 segs = nskb;
287 } while (segs);
288
289 return ret;
290}
291
292static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
293{
294 unsigned int mtu;
295 int ret;
296
297 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
298 if (ret) {
299 kfree_skb(skb);
300 return ret;
301 }
302
303#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
304 /* Policy lookup after SNAT yielded a new policy */
305 if (skb_dst(skb)->xfrm) {
306 IPCB(skb)->flags |= IPSKB_REROUTED;
307 return dst_output(net, sk, skb);
308 }
309#endif
310 mtu = ip_skb_dst_mtu(sk, skb);
311 if (skb_is_gso(skb))
312 return ip_finish_output_gso(net, sk, skb, mtu);
313
314 if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
315 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
316
317 return ip_finish_output2(net, sk, skb);
318}
319
320static int ip_mc_finish_output(struct net *net, struct sock *sk,
321 struct sk_buff *skb)
322{
323 int ret;
324
325 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
326 if (ret) {
327 kfree_skb(skb);
328 return ret;
329 }
330
331 return dev_loopback_xmit(net, sk, skb);
332}
333
334int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
335{
336 struct rtable *rt = skb_rtable(skb);
337 struct net_device *dev = rt->dst.dev;
338
339 /*
340 * If the indicated interface is up and running, send the packet.
341 */
342 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
343
344 skb->dev = dev;
345 skb->protocol = htons(ETH_P_IP);
346
347 /*
348 * Multicasts are looped back for other local users
349 */
350
351 if (rt->rt_flags&RTCF_MULTICAST) {
352 if (sk_mc_loop(sk)
353#ifdef CONFIG_IP_MROUTE
354 /* Small optimization: do not loopback not local frames,
355 which returned after forwarding; they will be dropped
356 by ip_mr_input in any case.
357 Note, that local frames are looped back to be delivered
358 to local recipients.
359
360 This check is duplicated in ip_mr_input at the moment.
361 */
362 &&
363 ((rt->rt_flags & RTCF_LOCAL) ||
364 !(IPCB(skb)->flags & IPSKB_FORWARDED))
365#endif
366 ) {
367 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
368 if (newskb)
369 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
370 net, sk, newskb, NULL, newskb->dev,
371 ip_mc_finish_output);
372 }
373
374 /* Multicasts with ttl 0 must not go beyond the host */
375
376 if (ip_hdr(skb)->ttl == 0) {
377 kfree_skb(skb);
378 return 0;
379 }
380 }
381
382 if (rt->rt_flags&RTCF_BROADCAST) {
383 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
384 if (newskb)
385 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
386 net, sk, newskb, NULL, newskb->dev,
387 ip_mc_finish_output);
388 }
389
390 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
391 net, sk, skb, NULL, skb->dev,
392 ip_finish_output,
393 !(IPCB(skb)->flags & IPSKB_REROUTED));
394}
395
396int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
397{
398 struct net_device *dev = skb_dst(skb)->dev;
399
400 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
401
402 skb->dev = dev;
403 skb->protocol = htons(ETH_P_IP);
404
405 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
406 net, sk, skb, NULL, dev,
407 ip_finish_output,
408 !(IPCB(skb)->flags & IPSKB_REROUTED));
409}
410
411/*
412 * copy saddr and daddr, possibly using 64bit load/stores
413 * Equivalent to :
414 * iph->saddr = fl4->saddr;
415 * iph->daddr = fl4->daddr;
416 */
417static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
418{
419 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
420 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
421 memcpy(&iph->saddr, &fl4->saddr,
422 sizeof(fl4->saddr) + sizeof(fl4->daddr));
423}
424
425/* Note: skb->sk can be different from sk, in case of tunnels */
426int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
427 __u8 tos)
428{
429 struct inet_sock *inet = inet_sk(sk);
430 struct net *net = sock_net(sk);
431 struct ip_options_rcu *inet_opt;
432 struct flowi4 *fl4;
433 struct rtable *rt;
434 struct iphdr *iph;
435 int res;
436
437 /* Skip all of this if the packet is already routed,
438 * f.e. by something like SCTP.
439 */
440 rcu_read_lock();
441 inet_opt = rcu_dereference(inet->inet_opt);
442 fl4 = &fl->u.ip4;
443 rt = skb_rtable(skb);
444 if (rt)
445 goto packet_routed;
446
447 /* Make sure we can route this packet. */
448 rt = (struct rtable *)__sk_dst_check(sk, 0);
449 if (!rt) {
450 __be32 daddr;
451
452 /* Use correct destination address if we have options. */
453 daddr = inet->inet_daddr;
454 if (inet_opt && inet_opt->opt.srr)
455 daddr = inet_opt->opt.faddr;
456
457 /* If this fails, retransmit mechanism of transport layer will
458 * keep trying until route appears or the connection times
459 * itself out.
460 */
461 rt = ip_route_output_ports(net, fl4, sk,
462 daddr, inet->inet_saddr,
463 inet->inet_dport,
464 inet->inet_sport,
465 sk->sk_protocol,
466 RT_CONN_FLAGS_TOS(sk, tos),
467 sk->sk_bound_dev_if);
468 if (IS_ERR(rt))
469 goto no_route;
470 sk_setup_caps(sk, &rt->dst);
471 }
472 skb_dst_set_noref(skb, &rt->dst);
473
474packet_routed:
475 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
476 goto no_route;
477
478 /* OK, we know where to send it, allocate and build IP header. */
479 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
480 skb_reset_network_header(skb);
481 iph = ip_hdr(skb);
482 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
483 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
484 iph->frag_off = htons(IP_DF);
485 else
486 iph->frag_off = 0;
487 iph->ttl = ip_select_ttl(inet, &rt->dst);
488 iph->protocol = sk->sk_protocol;
489 ip_copy_addrs(iph, fl4);
490
491 /* Transport layer set skb->h.foo itself. */
492
493 if (inet_opt && inet_opt->opt.optlen) {
494 iph->ihl += inet_opt->opt.optlen >> 2;
495 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
496 }
497
498 ip_select_ident_segs(net, skb, sk,
499 skb_shinfo(skb)->gso_segs ?: 1);
500
501 /* TODO : should we use skb->sk here instead of sk ? */
502 skb->priority = sk->sk_priority;
503 skb->mark = sk->sk_mark;
504
505 res = ip_local_out(net, sk, skb);
506 rcu_read_unlock();
507 return res;
508
509no_route:
510 rcu_read_unlock();
511 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
512 kfree_skb(skb);
513 return -EHOSTUNREACH;
514}
515EXPORT_SYMBOL(__ip_queue_xmit);
516
517static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
518{
519 to->pkt_type = from->pkt_type;
520 to->priority = from->priority;
521 to->protocol = from->protocol;
522 skb_dst_drop(to);
523 skb_dst_copy(to, from);
524 to->dev = from->dev;
525 to->mark = from->mark;
526
527 skb_copy_hash(to, from);
528
529 /* Copy the flags to each fragment. */
530 IPCB(to)->flags = IPCB(from)->flags;
531
532#ifdef CONFIG_NET_SCHED
533 to->tc_index = from->tc_index;
534#endif
535 nf_copy(to, from);
536 skb_ext_copy(to, from);
537#if IS_ENABLED(CONFIG_IP_VS)
538 to->ipvs_property = from->ipvs_property;
539#endif
540 skb_copy_secmark(to, from);
541}
542
543static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
544 unsigned int mtu,
545 int (*output)(struct net *, struct sock *, struct sk_buff *))
546{
547 struct iphdr *iph = ip_hdr(skb);
548
549 if ((iph->frag_off & htons(IP_DF)) == 0)
550 return ip_do_fragment(net, sk, skb, output);
551
552 if (unlikely(!skb->ignore_df ||
553 (IPCB(skb)->frag_max_size &&
554 IPCB(skb)->frag_max_size > mtu))) {
555 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
556 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
557 htonl(mtu));
558 kfree_skb(skb);
559 return -EMSGSIZE;
560 }
561
562 return ip_do_fragment(net, sk, skb, output);
563}
564
565/*
566 * This IP datagram is too large to be sent in one piece. Break it up into
567 * smaller pieces (each of size equal to IP header plus
568 * a block of the data of the original IP data part) that will yet fit in a
569 * single device frame, and queue such a frame for sending.
570 */
571
572int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
573 int (*output)(struct net *, struct sock *, struct sk_buff *))
574{
575 struct iphdr *iph;
576 int ptr;
577 struct sk_buff *skb2;
578 unsigned int mtu, hlen, left, len, ll_rs;
579 int offset;
580 __be16 not_last_frag;
581 struct rtable *rt = skb_rtable(skb);
582 int err = 0;
583
584 /* for offloaded checksums cleanup checksum before fragmentation */
585 if (skb->ip_summed == CHECKSUM_PARTIAL &&
586 (err = skb_checksum_help(skb)))
587 goto fail;
588
589 /*
590 * Point into the IP datagram header.
591 */
592
593 iph = ip_hdr(skb);
594
595 mtu = ip_skb_dst_mtu(sk, skb);
596 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
597 mtu = IPCB(skb)->frag_max_size;
598
599 /*
600 * Setup starting values.
601 */
602
603 hlen = iph->ihl * 4;
604 mtu = mtu - hlen; /* Size of data space */
605 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
606 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
607
608 /* When frag_list is given, use it. First, check its validity:
609 * some transformers could create wrong frag_list or break existing
610 * one, it is not prohibited. In this case fall back to copying.
611 *
612 * LATER: this step can be merged to real generation of fragments,
613 * we can switch to copy when see the first bad fragment.
614 */
615 if (skb_has_frag_list(skb)) {
616 struct sk_buff *frag, *frag2;
617 unsigned int first_len = skb_pagelen(skb);
618
619 if (first_len - hlen > mtu ||
620 ((first_len - hlen) & 7) ||
621 ip_is_fragment(iph) ||
622 skb_cloned(skb) ||
623 skb_headroom(skb) < ll_rs)
624 goto slow_path;
625
626 skb_walk_frags(skb, frag) {
627 /* Correct geometry. */
628 if (frag->len > mtu ||
629 ((frag->len & 7) && frag->next) ||
630 skb_headroom(frag) < hlen + ll_rs)
631 goto slow_path_clean;
632
633 /* Partially cloned skb? */
634 if (skb_shared(frag))
635 goto slow_path_clean;
636
637 BUG_ON(frag->sk);
638 if (skb->sk) {
639 frag->sk = skb->sk;
640 frag->destructor = sock_wfree;
641 }
642 skb->truesize -= frag->truesize;
643 }
644
645 /* Everything is OK. Generate! */
646
647 err = 0;
648 offset = 0;
649 frag = skb_shinfo(skb)->frag_list;
650 skb_frag_list_init(skb);
651 skb->data_len = first_len - skb_headlen(skb);
652 skb->len = first_len;
653 iph->tot_len = htons(first_len);
654 iph->frag_off = htons(IP_MF);
655 ip_send_check(iph);
656
657 for (;;) {
658 /* Prepare header of the next frame,
659 * before previous one went down. */
660 if (frag) {
661 frag->ip_summed = CHECKSUM_NONE;
662 skb_reset_transport_header(frag);
663 __skb_push(frag, hlen);
664 skb_reset_network_header(frag);
665 memcpy(skb_network_header(frag), iph, hlen);
666 iph = ip_hdr(frag);
667 iph->tot_len = htons(frag->len);
668 ip_copy_metadata(frag, skb);
669 if (offset == 0)
670 ip_options_fragment(frag);
671 offset += skb->len - hlen;
672 iph->frag_off = htons(offset>>3);
673 if (frag->next)
674 iph->frag_off |= htons(IP_MF);
675 /* Ready, complete checksum */
676 ip_send_check(iph);
677 }
678
679 err = output(net, sk, skb);
680
681 if (!err)
682 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
683 if (err || !frag)
684 break;
685
686 skb = frag;
687 frag = skb->next;
688 skb_mark_not_on_list(skb);
689 }
690
691 if (err == 0) {
692 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
693 return 0;
694 }
695
696 while (frag) {
697 skb = frag->next;
698 kfree_skb(frag);
699 frag = skb;
700 }
701 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
702 return err;
703
704slow_path_clean:
705 skb_walk_frags(skb, frag2) {
706 if (frag2 == frag)
707 break;
708 frag2->sk = NULL;
709 frag2->destructor = NULL;
710 skb->truesize += frag2->truesize;
711 }
712 }
713
714slow_path:
715 iph = ip_hdr(skb);
716
717 left = skb->len - hlen; /* Space per frame */
718 ptr = hlen; /* Where to start from */
719
720 /*
721 * Fragment the datagram.
722 */
723
724 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
725 not_last_frag = iph->frag_off & htons(IP_MF);
726
727 /*
728 * Keep copying data until we run out.
729 */
730
731 while (left > 0) {
732 len = left;
733 /* IF: it doesn't fit, use 'mtu' - the data space left */
734 if (len > mtu)
735 len = mtu;
736 /* IF: we are not sending up to and including the packet end
737 then align the next start on an eight byte boundary */
738 if (len < left) {
739 len &= ~7;
740 }
741
742 /* Allocate buffer */
743 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
744 if (!skb2) {
745 err = -ENOMEM;
746 goto fail;
747 }
748
749 /*
750 * Set up data on packet
751 */
752
753 ip_copy_metadata(skb2, skb);
754 skb_reserve(skb2, ll_rs);
755 skb_put(skb2, len + hlen);
756 skb_reset_network_header(skb2);
757 skb2->transport_header = skb2->network_header + hlen;
758
759 /*
760 * Charge the memory for the fragment to any owner
761 * it might possess
762 */
763
764 if (skb->sk)
765 skb_set_owner_w(skb2, skb->sk);
766
767 /*
768 * Copy the packet header into the new buffer.
769 */
770
771 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
772
773 /*
774 * Copy a block of the IP datagram.
775 */
776 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
777 BUG();
778 left -= len;
779
780 /*
781 * Fill in the new header fields.
782 */
783 iph = ip_hdr(skb2);
784 iph->frag_off = htons((offset >> 3));
785
786 if (IPCB(skb)->flags & IPSKB_FRAG_PMTU)
787 iph->frag_off |= htons(IP_DF);
788
789 /* ANK: dirty, but effective trick. Upgrade options only if
790 * the segment to be fragmented was THE FIRST (otherwise,
791 * options are already fixed) and make it ONCE
792 * on the initial skb, so that all the following fragments
793 * will inherit fixed options.
794 */
795 if (offset == 0)
796 ip_options_fragment(skb);
797
798 /*
799 * Added AC : If we are fragmenting a fragment that's not the
800 * last fragment then keep MF on each bit
801 */
802 if (left > 0 || not_last_frag)
803 iph->frag_off |= htons(IP_MF);
804 ptr += len;
805 offset += len;
806
807 /*
808 * Put this fragment into the sending queue.
809 */
810 iph->tot_len = htons(len + hlen);
811
812 ip_send_check(iph);
813
814 err = output(net, sk, skb2);
815 if (err)
816 goto fail;
817
818 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
819 }
820 consume_skb(skb);
821 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
822 return err;
823
824fail:
825 kfree_skb(skb);
826 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
827 return err;
828}
829EXPORT_SYMBOL(ip_do_fragment);
830
831int
832ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
833{
834 struct msghdr *msg = from;
835
836 if (skb->ip_summed == CHECKSUM_PARTIAL) {
837 if (!copy_from_iter_full(to, len, &msg->msg_iter))
838 return -EFAULT;
839 } else {
840 __wsum csum = 0;
841 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
842 return -EFAULT;
843 skb->csum = csum_block_add(skb->csum, csum, odd);
844 }
845 return 0;
846}
847EXPORT_SYMBOL(ip_generic_getfrag);
848
849static inline __wsum
850csum_page(struct page *page, int offset, int copy)
851{
852 char *kaddr;
853 __wsum csum;
854 kaddr = kmap(page);
855 csum = csum_partial(kaddr + offset, copy, 0);
856 kunmap(page);
857 return csum;
858}
859
860static int __ip_append_data(struct sock *sk,
861 struct flowi4 *fl4,
862 struct sk_buff_head *queue,
863 struct inet_cork *cork,
864 struct page_frag *pfrag,
865 int getfrag(void *from, char *to, int offset,
866 int len, int odd, struct sk_buff *skb),
867 void *from, int length, int transhdrlen,
868 unsigned int flags)
869{
870 struct inet_sock *inet = inet_sk(sk);
871 struct ubuf_info *uarg = NULL;
872 struct sk_buff *skb;
873
874 struct ip_options *opt = cork->opt;
875 int hh_len;
876 int exthdrlen;
877 int mtu;
878 int copy;
879 int err;
880 int offset = 0;
881 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
882 int csummode = CHECKSUM_NONE;
883 struct rtable *rt = (struct rtable *)cork->dst;
884 unsigned int wmem_alloc_delta = 0;
885 bool paged, extra_uref;
886 u32 tskey = 0;
887
888 skb = skb_peek_tail(queue);
889
890 exthdrlen = !skb ? rt->dst.header_len : 0;
891 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
892 paged = !!cork->gso_size;
893
894 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
895 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
896 tskey = sk->sk_tskey++;
897
898 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
899
900 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
901 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
902 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
903
904 if (cork->length + length > maxnonfragsize - fragheaderlen) {
905 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
906 mtu - (opt ? opt->optlen : 0));
907 return -EMSGSIZE;
908 }
909
910 /*
911 * transhdrlen > 0 means that this is the first fragment and we wish
912 * it won't be fragmented in the future.
913 */
914 if (transhdrlen &&
915 length + fragheaderlen <= mtu &&
916 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
917 (!(flags & MSG_MORE) || cork->gso_size) &&
918 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
919 csummode = CHECKSUM_PARTIAL;
920
921 if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) {
922 uarg = sock_zerocopy_realloc(sk, length, skb_zcopy(skb));
923 if (!uarg)
924 return -ENOBUFS;
925 extra_uref = true;
926 if (rt->dst.dev->features & NETIF_F_SG &&
927 csummode == CHECKSUM_PARTIAL) {
928 paged = true;
929 } else {
930 uarg->zerocopy = 0;
931 skb_zcopy_set(skb, uarg, &extra_uref);
932 }
933 }
934
935 cork->length += length;
936
937 /* So, what's going on in the loop below?
938 *
939 * We use calculated fragment length to generate chained skb,
940 * each of segments is IP fragment ready for sending to network after
941 * adding appropriate IP header.
942 */
943
944 if (!skb)
945 goto alloc_new_skb;
946
947 while (length > 0) {
948 /* Check if the remaining data fits into current packet. */
949 copy = mtu - skb->len;
950 if (copy < length)
951 copy = maxfraglen - skb->len;
952 if (copy <= 0) {
953 char *data;
954 unsigned int datalen;
955 unsigned int fraglen;
956 unsigned int fraggap;
957 unsigned int alloclen;
958 unsigned int pagedlen;
959 struct sk_buff *skb_prev;
960alloc_new_skb:
961 skb_prev = skb;
962 if (skb_prev)
963 fraggap = skb_prev->len - maxfraglen;
964 else
965 fraggap = 0;
966
967 /*
968 * If remaining data exceeds the mtu,
969 * we know we need more fragment(s).
970 */
971 datalen = length + fraggap;
972 if (datalen > mtu - fragheaderlen)
973 datalen = maxfraglen - fragheaderlen;
974 fraglen = datalen + fragheaderlen;
975 pagedlen = 0;
976
977 if ((flags & MSG_MORE) &&
978 !(rt->dst.dev->features&NETIF_F_SG))
979 alloclen = mtu;
980 else if (!paged)
981 alloclen = fraglen;
982 else {
983 alloclen = min_t(int, fraglen, MAX_HEADER);
984 pagedlen = fraglen - alloclen;
985 }
986
987 alloclen += exthdrlen;
988
989 /* The last fragment gets additional space at tail.
990 * Note, with MSG_MORE we overallocate on fragments,
991 * because we have no idea what fragment will be
992 * the last.
993 */
994 if (datalen == length + fraggap)
995 alloclen += rt->dst.trailer_len;
996
997 if (transhdrlen) {
998 skb = sock_alloc_send_skb(sk,
999 alloclen + hh_len + 15,
1000 (flags & MSG_DONTWAIT), &err);
1001 } else {
1002 skb = NULL;
1003 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1004 2 * sk->sk_sndbuf)
1005 skb = alloc_skb(alloclen + hh_len + 15,
1006 sk->sk_allocation);
1007 if (unlikely(!skb))
1008 err = -ENOBUFS;
1009 }
1010 if (!skb)
1011 goto error;
1012
1013 /*
1014 * Fill in the control structures
1015 */
1016 skb->ip_summed = csummode;
1017 skb->csum = 0;
1018 skb_reserve(skb, hh_len);
1019
1020 /*
1021 * Find where to start putting bytes.
1022 */
1023 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1024 skb_set_network_header(skb, exthdrlen);
1025 skb->transport_header = (skb->network_header +
1026 fragheaderlen);
1027 data += fragheaderlen + exthdrlen;
1028
1029 if (fraggap) {
1030 skb->csum = skb_copy_and_csum_bits(
1031 skb_prev, maxfraglen,
1032 data + transhdrlen, fraggap, 0);
1033 skb_prev->csum = csum_sub(skb_prev->csum,
1034 skb->csum);
1035 data += fraggap;
1036 pskb_trim_unique(skb_prev, maxfraglen);
1037 }
1038
1039 copy = datalen - transhdrlen - fraggap - pagedlen;
1040 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1041 err = -EFAULT;
1042 kfree_skb(skb);
1043 goto error;
1044 }
1045
1046 offset += copy;
1047 length -= copy + transhdrlen;
1048 transhdrlen = 0;
1049 exthdrlen = 0;
1050 csummode = CHECKSUM_NONE;
1051
1052 /* only the initial fragment is time stamped */
1053 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1054 cork->tx_flags = 0;
1055 skb_shinfo(skb)->tskey = tskey;
1056 tskey = 0;
1057 skb_zcopy_set(skb, uarg, &extra_uref);
1058
1059 if ((flags & MSG_CONFIRM) && !skb_prev)
1060 skb_set_dst_pending_confirm(skb, 1);
1061
1062 /*
1063 * Put the packet on the pending queue.
1064 */
1065 if (!skb->destructor) {
1066 skb->destructor = sock_wfree;
1067 skb->sk = sk;
1068 wmem_alloc_delta += skb->truesize;
1069 }
1070 __skb_queue_tail(queue, skb);
1071 continue;
1072 }
1073
1074 if (copy > length)
1075 copy = length;
1076
1077 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1078 skb_tailroom(skb) >= copy) {
1079 unsigned int off;
1080
1081 off = skb->len;
1082 if (getfrag(from, skb_put(skb, copy),
1083 offset, copy, off, skb) < 0) {
1084 __skb_trim(skb, off);
1085 err = -EFAULT;
1086 goto error;
1087 }
1088 } else if (!uarg || !uarg->zerocopy) {
1089 int i = skb_shinfo(skb)->nr_frags;
1090
1091 err = -ENOMEM;
1092 if (!sk_page_frag_refill(sk, pfrag))
1093 goto error;
1094
1095 if (!skb_can_coalesce(skb, i, pfrag->page,
1096 pfrag->offset)) {
1097 err = -EMSGSIZE;
1098 if (i == MAX_SKB_FRAGS)
1099 goto error;
1100
1101 __skb_fill_page_desc(skb, i, pfrag->page,
1102 pfrag->offset, 0);
1103 skb_shinfo(skb)->nr_frags = ++i;
1104 get_page(pfrag->page);
1105 }
1106 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1107 if (getfrag(from,
1108 page_address(pfrag->page) + pfrag->offset,
1109 offset, copy, skb->len, skb) < 0)
1110 goto error_efault;
1111
1112 pfrag->offset += copy;
1113 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1114 skb->len += copy;
1115 skb->data_len += copy;
1116 skb->truesize += copy;
1117 wmem_alloc_delta += copy;
1118 } else {
1119 err = skb_zerocopy_iter_dgram(skb, from, copy);
1120 if (err < 0)
1121 goto error;
1122 }
1123 offset += copy;
1124 length -= copy;
1125 }
1126
1127 if (wmem_alloc_delta)
1128 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1129 return 0;
1130
1131error_efault:
1132 err = -EFAULT;
1133error:
1134 if (uarg)
1135 sock_zerocopy_put_abort(uarg, extra_uref);
1136 cork->length -= length;
1137 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1138 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1139 return err;
1140}
1141
1142static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1143 struct ipcm_cookie *ipc, struct rtable **rtp)
1144{
1145 struct ip_options_rcu *opt;
1146 struct rtable *rt;
1147
1148 rt = *rtp;
1149 if (unlikely(!rt))
1150 return -EFAULT;
1151
1152 /*
1153 * setup for corking.
1154 */
1155 opt = ipc->opt;
1156 if (opt) {
1157 if (!cork->opt) {
1158 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1159 sk->sk_allocation);
1160 if (unlikely(!cork->opt))
1161 return -ENOBUFS;
1162 }
1163 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1164 cork->flags |= IPCORK_OPT;
1165 cork->addr = ipc->addr;
1166 }
1167
1168 /*
1169 * We steal reference to this route, caller should not release it
1170 */
1171 *rtp = NULL;
1172 cork->fragsize = ip_sk_use_pmtu(sk) ?
1173 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1174
1175 cork->gso_size = ipc->gso_size;
1176 cork->dst = &rt->dst;
1177 cork->length = 0;
1178 cork->ttl = ipc->ttl;
1179 cork->tos = ipc->tos;
1180 cork->priority = ipc->priority;
1181 cork->transmit_time = ipc->sockc.transmit_time;
1182 cork->tx_flags = 0;
1183 sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags);
1184
1185 return 0;
1186}
1187
1188/*
1189 * ip_append_data() and ip_append_page() can make one large IP datagram
1190 * from many pieces of data. Each pieces will be holded on the socket
1191 * until ip_push_pending_frames() is called. Each piece can be a page
1192 * or non-page data.
1193 *
1194 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1195 * this interface potentially.
1196 *
1197 * LATER: length must be adjusted by pad at tail, when it is required.
1198 */
1199int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1200 int getfrag(void *from, char *to, int offset, int len,
1201 int odd, struct sk_buff *skb),
1202 void *from, int length, int transhdrlen,
1203 struct ipcm_cookie *ipc, struct rtable **rtp,
1204 unsigned int flags)
1205{
1206 struct inet_sock *inet = inet_sk(sk);
1207 int err;
1208
1209 if (flags&MSG_PROBE)
1210 return 0;
1211
1212 if (skb_queue_empty(&sk->sk_write_queue)) {
1213 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1214 if (err)
1215 return err;
1216 } else {
1217 transhdrlen = 0;
1218 }
1219
1220 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1221 sk_page_frag(sk), getfrag,
1222 from, length, transhdrlen, flags);
1223}
1224
1225ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1226 int offset, size_t size, int flags)
1227{
1228 struct inet_sock *inet = inet_sk(sk);
1229 struct sk_buff *skb;
1230 struct rtable *rt;
1231 struct ip_options *opt = NULL;
1232 struct inet_cork *cork;
1233 int hh_len;
1234 int mtu;
1235 int len;
1236 int err;
1237 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1238
1239 if (inet->hdrincl)
1240 return -EPERM;
1241
1242 if (flags&MSG_PROBE)
1243 return 0;
1244
1245 if (skb_queue_empty(&sk->sk_write_queue))
1246 return -EINVAL;
1247
1248 cork = &inet->cork.base;
1249 rt = (struct rtable *)cork->dst;
1250 if (cork->flags & IPCORK_OPT)
1251 opt = cork->opt;
1252
1253 if (!(rt->dst.dev->features&NETIF_F_SG))
1254 return -EOPNOTSUPP;
1255
1256 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1257 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
1258
1259 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1260 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1261 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1262
1263 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1264 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1265 mtu - (opt ? opt->optlen : 0));
1266 return -EMSGSIZE;
1267 }
1268
1269 skb = skb_peek_tail(&sk->sk_write_queue);
1270 if (!skb)
1271 return -EINVAL;
1272
1273 cork->length += size;
1274
1275 while (size > 0) {
1276 /* Check if the remaining data fits into current packet. */
1277 len = mtu - skb->len;
1278 if (len < size)
1279 len = maxfraglen - skb->len;
1280
1281 if (len <= 0) {
1282 struct sk_buff *skb_prev;
1283 int alloclen;
1284
1285 skb_prev = skb;
1286 fraggap = skb_prev->len - maxfraglen;
1287
1288 alloclen = fragheaderlen + hh_len + fraggap + 15;
1289 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1290 if (unlikely(!skb)) {
1291 err = -ENOBUFS;
1292 goto error;
1293 }
1294
1295 /*
1296 * Fill in the control structures
1297 */
1298 skb->ip_summed = CHECKSUM_NONE;
1299 skb->csum = 0;
1300 skb_reserve(skb, hh_len);
1301
1302 /*
1303 * Find where to start putting bytes.
1304 */
1305 skb_put(skb, fragheaderlen + fraggap);
1306 skb_reset_network_header(skb);
1307 skb->transport_header = (skb->network_header +
1308 fragheaderlen);
1309 if (fraggap) {
1310 skb->csum = skb_copy_and_csum_bits(skb_prev,
1311 maxfraglen,
1312 skb_transport_header(skb),
1313 fraggap, 0);
1314 skb_prev->csum = csum_sub(skb_prev->csum,
1315 skb->csum);
1316 pskb_trim_unique(skb_prev, maxfraglen);
1317 }
1318
1319 /*
1320 * Put the packet on the pending queue.
1321 */
1322 __skb_queue_tail(&sk->sk_write_queue, skb);
1323 continue;
1324 }
1325
1326 if (len > size)
1327 len = size;
1328
1329 if (skb_append_pagefrags(skb, page, offset, len)) {
1330 err = -EMSGSIZE;
1331 goto error;
1332 }
1333
1334 if (skb->ip_summed == CHECKSUM_NONE) {
1335 __wsum csum;
1336 csum = csum_page(page, offset, len);
1337 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1338 }
1339
1340 skb->len += len;
1341 skb->data_len += len;
1342 skb->truesize += len;
1343 refcount_add(len, &sk->sk_wmem_alloc);
1344 offset += len;
1345 size -= len;
1346 }
1347 return 0;
1348
1349error:
1350 cork->length -= size;
1351 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1352 return err;
1353}
1354
1355static void ip_cork_release(struct inet_cork *cork)
1356{
1357 cork->flags &= ~IPCORK_OPT;
1358 kfree(cork->opt);
1359 cork->opt = NULL;
1360 dst_release(cork->dst);
1361 cork->dst = NULL;
1362}
1363
1364/*
1365 * Combined all pending IP fragments on the socket as one IP datagram
1366 * and push them out.
1367 */
1368struct sk_buff *__ip_make_skb(struct sock *sk,
1369 struct flowi4 *fl4,
1370 struct sk_buff_head *queue,
1371 struct inet_cork *cork)
1372{
1373 struct sk_buff *skb, *tmp_skb;
1374 struct sk_buff **tail_skb;
1375 struct inet_sock *inet = inet_sk(sk);
1376 struct net *net = sock_net(sk);
1377 struct ip_options *opt = NULL;
1378 struct rtable *rt = (struct rtable *)cork->dst;
1379 struct iphdr *iph;
1380 __be16 df = 0;
1381 __u8 ttl;
1382
1383 skb = __skb_dequeue(queue);
1384 if (!skb)
1385 goto out;
1386 tail_skb = &(skb_shinfo(skb)->frag_list);
1387
1388 /* move skb->data to ip header from ext header */
1389 if (skb->data < skb_network_header(skb))
1390 __skb_pull(skb, skb_network_offset(skb));
1391 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1392 __skb_pull(tmp_skb, skb_network_header_len(skb));
1393 *tail_skb = tmp_skb;
1394 tail_skb = &(tmp_skb->next);
1395 skb->len += tmp_skb->len;
1396 skb->data_len += tmp_skb->len;
1397 skb->truesize += tmp_skb->truesize;
1398 tmp_skb->destructor = NULL;
1399 tmp_skb->sk = NULL;
1400 }
1401
1402 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1403 * to fragment the frame generated here. No matter, what transforms
1404 * how transforms change size of the packet, it will come out.
1405 */
1406 skb->ignore_df = ip_sk_ignore_df(sk);
1407
1408 /* DF bit is set when we want to see DF on outgoing frames.
1409 * If ignore_df is set too, we still allow to fragment this frame
1410 * locally. */
1411 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1412 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1413 (skb->len <= dst_mtu(&rt->dst) &&
1414 ip_dont_fragment(sk, &rt->dst)))
1415 df = htons(IP_DF);
1416
1417 if (cork->flags & IPCORK_OPT)
1418 opt = cork->opt;
1419
1420 if (cork->ttl != 0)
1421 ttl = cork->ttl;
1422 else if (rt->rt_type == RTN_MULTICAST)
1423 ttl = inet->mc_ttl;
1424 else
1425 ttl = ip_select_ttl(inet, &rt->dst);
1426
1427 iph = ip_hdr(skb);
1428 iph->version = 4;
1429 iph->ihl = 5;
1430 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1431 iph->frag_off = df;
1432 iph->ttl = ttl;
1433 iph->protocol = sk->sk_protocol;
1434 ip_copy_addrs(iph, fl4);
1435 ip_select_ident(net, skb, sk);
1436
1437 if (opt) {
1438 iph->ihl += opt->optlen>>2;
1439 ip_options_build(skb, opt, cork->addr, rt, 0);
1440 }
1441
1442 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1443 skb->mark = sk->sk_mark;
1444 skb->tstamp = cork->transmit_time;
1445 /*
1446 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1447 * on dst refcount
1448 */
1449 cork->dst = NULL;
1450 skb_dst_set(skb, &rt->dst);
1451
1452 if (iph->protocol == IPPROTO_ICMP)
1453 icmp_out_count(net, ((struct icmphdr *)
1454 skb_transport_header(skb))->type);
1455
1456 ip_cork_release(cork);
1457out:
1458 return skb;
1459}
1460
1461int ip_send_skb(struct net *net, struct sk_buff *skb)
1462{
1463 int err;
1464
1465 err = ip_local_out(net, skb->sk, skb);
1466 if (err) {
1467 if (err > 0)
1468 err = net_xmit_errno(err);
1469 if (err)
1470 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1471 }
1472
1473 return err;
1474}
1475
1476int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1477{
1478 struct sk_buff *skb;
1479
1480 skb = ip_finish_skb(sk, fl4);
1481 if (!skb)
1482 return 0;
1483
1484 /* Netfilter gets whole the not fragmented skb. */
1485 return ip_send_skb(sock_net(sk), skb);
1486}
1487
1488/*
1489 * Throw away all pending data on the socket.
1490 */
1491static void __ip_flush_pending_frames(struct sock *sk,
1492 struct sk_buff_head *queue,
1493 struct inet_cork *cork)
1494{
1495 struct sk_buff *skb;
1496
1497 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1498 kfree_skb(skb);
1499
1500 ip_cork_release(cork);
1501}
1502
1503void ip_flush_pending_frames(struct sock *sk)
1504{
1505 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1506}
1507
1508struct sk_buff *ip_make_skb(struct sock *sk,
1509 struct flowi4 *fl4,
1510 int getfrag(void *from, char *to, int offset,
1511 int len, int odd, struct sk_buff *skb),
1512 void *from, int length, int transhdrlen,
1513 struct ipcm_cookie *ipc, struct rtable **rtp,
1514 struct inet_cork *cork, unsigned int flags)
1515{
1516 struct sk_buff_head queue;
1517 int err;
1518
1519 if (flags & MSG_PROBE)
1520 return NULL;
1521
1522 __skb_queue_head_init(&queue);
1523
1524 cork->flags = 0;
1525 cork->addr = 0;
1526 cork->opt = NULL;
1527 err = ip_setup_cork(sk, cork, ipc, rtp);
1528 if (err)
1529 return ERR_PTR(err);
1530
1531 err = __ip_append_data(sk, fl4, &queue, cork,
1532 &current->task_frag, getfrag,
1533 from, length, transhdrlen, flags);
1534 if (err) {
1535 __ip_flush_pending_frames(sk, &queue, cork);
1536 return ERR_PTR(err);
1537 }
1538
1539 return __ip_make_skb(sk, fl4, &queue, cork);
1540}
1541
1542/*
1543 * Fetch data from kernel space and fill in checksum if needed.
1544 */
1545static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1546 int len, int odd, struct sk_buff *skb)
1547{
1548 __wsum csum;
1549
1550 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1551 skb->csum = csum_block_add(skb->csum, csum, odd);
1552 return 0;
1553}
1554
1555/*
1556 * Generic function to send a packet as reply to another packet.
1557 * Used to send some TCP resets/acks so far.
1558 */
1559void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1560 const struct ip_options *sopt,
1561 __be32 daddr, __be32 saddr,
1562 const struct ip_reply_arg *arg,
1563 unsigned int len)
1564{
1565 struct ip_options_data replyopts;
1566 struct ipcm_cookie ipc;
1567 struct flowi4 fl4;
1568 struct rtable *rt = skb_rtable(skb);
1569 struct net *net = sock_net(sk);
1570 struct sk_buff *nskb;
1571 int err;
1572 int oif;
1573
1574 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1575 return;
1576
1577 ipcm_init(&ipc);
1578 ipc.addr = daddr;
1579
1580 if (replyopts.opt.opt.optlen) {
1581 ipc.opt = &replyopts.opt;
1582
1583 if (replyopts.opt.opt.srr)
1584 daddr = replyopts.opt.opt.faddr;
1585 }
1586
1587 oif = arg->bound_dev_if;
1588 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1589 oif = skb->skb_iif;
1590
1591 flowi4_init_output(&fl4, oif,
1592 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1593 RT_TOS(arg->tos),
1594 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1595 ip_reply_arg_flowi_flags(arg),
1596 daddr, saddr,
1597 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1598 arg->uid);
1599 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1600 rt = ip_route_output_key(net, &fl4);
1601 if (IS_ERR(rt))
1602 return;
1603
1604 inet_sk(sk)->tos = arg->tos;
1605
1606 sk->sk_priority = skb->priority;
1607 sk->sk_protocol = ip_hdr(skb)->protocol;
1608 sk->sk_bound_dev_if = arg->bound_dev_if;
1609 sk->sk_sndbuf = sysctl_wmem_default;
1610 sk->sk_mark = fl4.flowi4_mark;
1611 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1612 len, 0, &ipc, &rt, MSG_DONTWAIT);
1613 if (unlikely(err)) {
1614 ip_flush_pending_frames(sk);
1615 goto out;
1616 }
1617
1618 nskb = skb_peek(&sk->sk_write_queue);
1619 if (nskb) {
1620 if (arg->csumoffset >= 0)
1621 *((__sum16 *)skb_transport_header(nskb) +
1622 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1623 arg->csum));
1624 nskb->ip_summed = CHECKSUM_NONE;
1625 ip_push_pending_frames(sk, &fl4);
1626 }
1627out:
1628 ip_rt_put(rt);
1629}
1630
1631void __init ip_init(void)
1632{
1633 ip_rt_init();
1634 inet_initpeers();
1635
1636#if defined(CONFIG_IP_MULTICAST)
1637 igmp_mc_init();
1638#endif
1639}
1640