1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * The Internet Protocol (IP) output module.
8 *
9 * Authors: Ross Biro
10 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11 * Donald Becker, <becker@super.org>
12 * Alan Cox, <Alan.Cox@linux.org>
13 * Richard Underwood
14 * Stefan Becker, <stefanb@yello.ping.de>
15 * Jorge Cwik, <jorge@laser.satlink.net>
16 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
17 * Hirokazu Takahashi, <taka@valinux.co.jp>
18 *
19 * See ip_input.c for original log
20 *
21 * Fixes:
22 * Alan Cox : Missing nonblock feature in ip_build_xmit.
23 * Mike Kilburn : htons() missing in ip_build_xmit.
24 * Bradford Johnson: Fix faulty handling of some frames when
25 * no route is found.
26 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
27 * (in case if packet not accepted by
28 * output firewall rules)
29 * Mike McLagan : Routing by source
30 * Alexey Kuznetsov: use new route cache
31 * Andi Kleen: Fix broken PMTU recovery and remove
32 * some redundant tests.
33 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
34 * Andi Kleen : Replace ip_reply with ip_send_reply.
35 * Andi Kleen : Split fast and slow ip_build_xmit path
36 * for decreased register pressure on x86
37 * and more readability.
38 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
39 * silently drop skb instead of failing with -EPERM.
40 * Detlev Wengorz : Copy protocol for fragments.
41 * Hirokazu Takahashi: HW checksumming for outgoing UDP
42 * datagrams.
43 * Hirokazu Takahashi: sendfile() on UDP works now.
44 */
45
46 #include <linux/uaccess.h>
47 #include <linux/module.h>
48 #include <linux/types.h>
49 #include <linux/kernel.h>
50 #include <linux/mm.h>
51 #include <linux/string.h>
52 #include <linux/errno.h>
53 #include <linux/highmem.h>
54 #include <linux/slab.h>
55
56 #include <linux/socket.h>
57 #include <linux/sockios.h>
58 #include <linux/in.h>
59 #include <linux/inet.h>
60 #include <linux/netdevice.h>
61 #include <linux/etherdevice.h>
62 #include <linux/proc_fs.h>
63 #include <linux/stat.h>
64 #include <linux/init.h>
65
66 #include <net/snmp.h>
67 #include <net/ip.h>
68 #include <net/protocol.h>
69 #include <net/route.h>
70 #include <net/xfrm.h>
71 #include <linux/skbuff.h>
72 #include <net/sock.h>
73 #include <net/arp.h>
74 #include <net/icmp.h>
75 #include <net/checksum.h>
76 #include <net/gso.h>
77 #include <net/inetpeer.h>
78 #include <net/lwtunnel.h>
79 #include <net/inet_dscp.h>
80 #include <linux/bpf-cgroup.h>
81 #include <linux/igmp.h>
82 #include <linux/netfilter_ipv4.h>
83 #include <linux/netfilter_bridge.h>
84 #include <linux/netlink.h>
85 #include <linux/tcp.h>
86
87 static int
88 ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
89 unsigned int mtu,
90 int (*output)(struct net *, struct sock *, struct sk_buff *));
91
92 /* Generate a checksum for an outgoing IP datagram. */
ip_send_check(struct iphdr * iph)93 void ip_send_check(struct iphdr *iph)
94 {
95 iph->check = 0;
96 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
97 }
98 EXPORT_SYMBOL(ip_send_check);
99
__ip_local_out(struct net * net,struct sock * sk,struct sk_buff * skb)100 int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
101 {
102 struct iphdr *iph = ip_hdr(skb);
103
104 IP_INC_STATS(net, IPSTATS_MIB_OUTREQUESTS);
105
106 iph_set_totlen(iph, skb->len);
107 ip_send_check(iph);
108
109 /* if egress device is enslaved to an L3 master device pass the
110 * skb to its handler for processing
111 */
112 skb = l3mdev_ip_out(sk, skb);
113 if (unlikely(!skb))
114 return 0;
115
116 skb->protocol = htons(ETH_P_IP);
117
118 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
119 net, sk, skb, NULL, skb_dst(skb)->dev,
120 dst_output);
121 }
122
ip_local_out(struct net * net,struct sock * sk,struct sk_buff * skb)123 int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
124 {
125 int err;
126
127 err = __ip_local_out(net, sk, skb);
128 if (likely(err == 1))
129 err = dst_output(net, sk, skb);
130
131 return err;
132 }
133 EXPORT_SYMBOL_GPL(ip_local_out);
134
ip_select_ttl(const struct inet_sock * inet,const struct dst_entry * dst)135 static inline int ip_select_ttl(const struct inet_sock *inet,
136 const struct dst_entry *dst)
137 {
138 int ttl = READ_ONCE(inet->uc_ttl);
139
140 if (ttl < 0)
141 ttl = ip4_dst_hoplimit(dst);
142 return ttl;
143 }
144
145 /*
146 * Add an ip header to a skbuff and send it out.
147 *
148 */
ip_build_and_send_pkt(struct sk_buff * skb,const struct sock * sk,__be32 saddr,__be32 daddr,struct ip_options_rcu * opt,u8 tos)149 int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
150 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt,
151 u8 tos)
152 {
153 const struct inet_sock *inet = inet_sk(sk);
154 struct rtable *rt = skb_rtable(skb);
155 struct net *net = sock_net(sk);
156 struct iphdr *iph;
157
158 /* Build the IP header. */
159 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
160 skb_reset_network_header(skb);
161 iph = ip_hdr(skb);
162 iph->version = 4;
163 iph->ihl = 5;
164 iph->tos = tos;
165 iph->ttl = ip_select_ttl(inet, &rt->dst);
166 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
167 iph->saddr = saddr;
168 iph->protocol = sk->sk_protocol;
169 /* Do not bother generating IPID for small packets (eg SYNACK) */
170 if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) {
171 iph->frag_off = htons(IP_DF);
172 iph->id = 0;
173 } else {
174 iph->frag_off = 0;
175 /* TCP packets here are SYNACK with fat IPv4/TCP options.
176 * Avoid using the hashed IP ident generator.
177 */
178 if (sk->sk_protocol == IPPROTO_TCP)
179 iph->id = (__force __be16)get_random_u16();
180 else
181 __ip_select_ident(net, iph, 1);
182 }
183
184 if (opt && opt->opt.optlen) {
185 iph->ihl += opt->opt.optlen>>2;
186 ip_options_build(skb, &opt->opt, daddr, rt);
187 }
188
189 skb->priority = READ_ONCE(sk->sk_priority);
190 if (!skb->mark)
191 skb->mark = READ_ONCE(sk->sk_mark);
192
193 /* Send it out. */
194 return ip_local_out(net, skb->sk, skb);
195 }
196 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
197
ip_finish_output2(struct net * net,struct sock * sk,struct sk_buff * skb)198 static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
199 {
200 struct dst_entry *dst = skb_dst(skb);
201 struct rtable *rt = dst_rtable(dst);
202 struct net_device *dev = dst->dev;
203 unsigned int hh_len = LL_RESERVED_SPACE(dev);
204 struct neighbour *neigh;
205 bool is_v6gw = false;
206
207 if (rt->rt_type == RTN_MULTICAST) {
208 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
209 } else if (rt->rt_type == RTN_BROADCAST)
210 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
211
212 /* OUTOCTETS should be counted after fragment */
213 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
214
215 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
216 skb = skb_expand_head(skb, hh_len);
217 if (!skb)
218 return -ENOMEM;
219 }
220
221 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
222 int res = lwtunnel_xmit(skb);
223
224 if (res != LWTUNNEL_XMIT_CONTINUE)
225 return res;
226 }
227
228 rcu_read_lock();
229 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
230 if (!IS_ERR(neigh)) {
231 int res;
232
233 sock_confirm_neigh(skb, neigh);
234 /* if crossing protocols, can not use the cached header */
235 res = neigh_output(neigh, skb, is_v6gw);
236 rcu_read_unlock();
237 return res;
238 }
239 rcu_read_unlock();
240
241 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
242 __func__);
243 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
244 return PTR_ERR(neigh);
245 }
246
ip_finish_output_gso(struct net * net,struct sock * sk,struct sk_buff * skb,unsigned int mtu)247 static int ip_finish_output_gso(struct net *net, struct sock *sk,
248 struct sk_buff *skb, unsigned int mtu)
249 {
250 struct sk_buff *segs, *nskb;
251 netdev_features_t features;
252 int ret = 0;
253
254 /* common case: seglen is <= mtu
255 */
256 if (skb_gso_validate_network_len(skb, mtu))
257 return ip_finish_output2(net, sk, skb);
258
259 /* Slowpath - GSO segment length exceeds the egress MTU.
260 *
261 * This can happen in several cases:
262 * - Forwarding of a TCP GRO skb, when DF flag is not set.
263 * - Forwarding of an skb that arrived on a virtualization interface
264 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
265 * stack.
266 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
267 * interface with a smaller MTU.
268 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
269 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
270 * insufficient MTU.
271 */
272 features = netif_skb_features(skb);
273 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
274 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
275 if (IS_ERR_OR_NULL(segs)) {
276 kfree_skb(skb);
277 return -ENOMEM;
278 }
279
280 consume_skb(skb);
281
282 skb_list_walk_safe(segs, segs, nskb) {
283 int err;
284
285 skb_mark_not_on_list(segs);
286 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
287
288 if (err && ret == 0)
289 ret = err;
290 }
291
292 return ret;
293 }
294
__ip_finish_output(struct net * net,struct sock * sk,struct sk_buff * skb)295 static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
296 {
297 unsigned int mtu;
298
299 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
300 /* Policy lookup after SNAT yielded a new policy */
301 if (skb_dst(skb)->xfrm) {
302 IPCB(skb)->flags |= IPSKB_REROUTED;
303 return dst_output(net, sk, skb);
304 }
305 #endif
306 mtu = ip_skb_dst_mtu(sk, skb);
307 if (skb_is_gso(skb))
308 return ip_finish_output_gso(net, sk, skb, mtu);
309
310 if (skb->len > mtu || IPCB(skb)->frag_max_size)
311 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
312
313 return ip_finish_output2(net, sk, skb);
314 }
315
ip_finish_output(struct net * net,struct sock * sk,struct sk_buff * skb)316 static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
317 {
318 int ret;
319
320 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
321 switch (ret) {
322 case NET_XMIT_SUCCESS:
323 return __ip_finish_output(net, sk, skb);
324 case NET_XMIT_CN:
325 return __ip_finish_output(net, sk, skb) ? : ret;
326 default:
327 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
328 return ret;
329 }
330 }
331
ip_mc_finish_output(struct net * net,struct sock * sk,struct sk_buff * skb)332 static int ip_mc_finish_output(struct net *net, struct sock *sk,
333 struct sk_buff *skb)
334 {
335 struct rtable *new_rt;
336 bool do_cn = false;
337 int ret, err;
338
339 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
340 switch (ret) {
341 case NET_XMIT_CN:
342 do_cn = true;
343 fallthrough;
344 case NET_XMIT_SUCCESS:
345 break;
346 default:
347 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
348 return ret;
349 }
350
351 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
352 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
353 * see ipv4_pktinfo_prepare().
354 */
355 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
356 if (new_rt) {
357 new_rt->rt_iif = 0;
358 skb_dst_drop(skb);
359 skb_dst_set(skb, &new_rt->dst);
360 }
361
362 err = dev_loopback_xmit(net, sk, skb);
363 return (do_cn && err) ? ret : err;
364 }
365
ip_mc_output(struct net * net,struct sock * sk,struct sk_buff * skb)366 int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
367 {
368 struct rtable *rt = skb_rtable(skb);
369 struct net_device *dev = rt->dst.dev;
370
371 /*
372 * If the indicated interface is up and running, send the packet.
373 */
374 skb->dev = dev;
375 skb->protocol = htons(ETH_P_IP);
376
377 /*
378 * Multicasts are looped back for other local users
379 */
380
381 if (rt->rt_flags&RTCF_MULTICAST) {
382 if (sk_mc_loop(sk)
383 #ifdef CONFIG_IP_MROUTE
384 /* Small optimization: do not loopback not local frames,
385 which returned after forwarding; they will be dropped
386 by ip_mr_input in any case.
387 Note, that local frames are looped back to be delivered
388 to local recipients.
389
390 This check is duplicated in ip_mr_input at the moment.
391 */
392 &&
393 ((rt->rt_flags & RTCF_LOCAL) ||
394 !(IPCB(skb)->flags & IPSKB_FORWARDED))
395 #endif
396 ) {
397 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
398 if (newskb)
399 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
400 net, sk, newskb, NULL, newskb->dev,
401 ip_mc_finish_output);
402 }
403
404 /* Multicasts with ttl 0 must not go beyond the host */
405
406 if (ip_hdr(skb)->ttl == 0) {
407 kfree_skb(skb);
408 return 0;
409 }
410 }
411
412 if (rt->rt_flags&RTCF_BROADCAST) {
413 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
414 if (newskb)
415 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
416 net, sk, newskb, NULL, newskb->dev,
417 ip_mc_finish_output);
418 }
419
420 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
421 net, sk, skb, NULL, skb->dev,
422 ip_finish_output,
423 !(IPCB(skb)->flags & IPSKB_REROUTED));
424 }
425
ip_output(struct net * net,struct sock * sk,struct sk_buff * skb)426 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
427 {
428 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
429
430 skb->dev = dev;
431 skb->protocol = htons(ETH_P_IP);
432
433 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
434 net, sk, skb, indev, dev,
435 ip_finish_output,
436 !(IPCB(skb)->flags & IPSKB_REROUTED));
437 }
438 EXPORT_SYMBOL(ip_output);
439
440 /*
441 * copy saddr and daddr, possibly using 64bit load/stores
442 * Equivalent to :
443 * iph->saddr = fl4->saddr;
444 * iph->daddr = fl4->daddr;
445 */
ip_copy_addrs(struct iphdr * iph,const struct flowi4 * fl4)446 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
447 {
448 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
449 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
450
451 iph->saddr = fl4->saddr;
452 iph->daddr = fl4->daddr;
453 }
454
455 /* Note: skb->sk can be different from sk, in case of tunnels */
__ip_queue_xmit(struct sock * sk,struct sk_buff * skb,struct flowi * fl,__u8 tos)456 int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
457 __u8 tos)
458 {
459 struct inet_sock *inet = inet_sk(sk);
460 struct net *net = sock_net(sk);
461 struct ip_options_rcu *inet_opt;
462 struct flowi4 *fl4;
463 struct rtable *rt;
464 struct iphdr *iph;
465 int res;
466
467 /* Skip all of this if the packet is already routed,
468 * f.e. by something like SCTP.
469 */
470 rcu_read_lock();
471 inet_opt = rcu_dereference(inet->inet_opt);
472 fl4 = &fl->u.ip4;
473 rt = skb_rtable(skb);
474 if (rt)
475 goto packet_routed;
476
477 /* Make sure we can route this packet. */
478 rt = dst_rtable(__sk_dst_check(sk, 0));
479 if (!rt) {
480 inet_sk_init_flowi4(inet, fl4);
481
482 /* sctp_v4_xmit() uses its own DSCP value */
483 fl4->flowi4_tos = tos & INET_DSCP_MASK;
484
485 /* If this fails, retransmit mechanism of transport layer will
486 * keep trying until route appears or the connection times
487 * itself out.
488 */
489 rt = ip_route_output_flow(net, fl4, sk);
490 if (IS_ERR(rt))
491 goto no_route;
492 sk_setup_caps(sk, &rt->dst);
493 }
494 skb_dst_set_noref(skb, &rt->dst);
495
496 packet_routed:
497 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
498 goto no_route;
499
500 /* OK, we know where to send it, allocate and build IP header. */
501 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
502 skb_reset_network_header(skb);
503 iph = ip_hdr(skb);
504 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
505 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
506 iph->frag_off = htons(IP_DF);
507 else
508 iph->frag_off = 0;
509 iph->ttl = ip_select_ttl(inet, &rt->dst);
510 iph->protocol = sk->sk_protocol;
511 ip_copy_addrs(iph, fl4);
512
513 /* Transport layer set skb->h.foo itself. */
514
515 if (inet_opt && inet_opt->opt.optlen) {
516 iph->ihl += inet_opt->opt.optlen >> 2;
517 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt);
518 }
519
520 ip_select_ident_segs(net, skb, sk,
521 skb_shinfo(skb)->gso_segs ?: 1);
522
523 /* TODO : should we use skb->sk here instead of sk ? */
524 skb->priority = READ_ONCE(sk->sk_priority);
525 skb->mark = READ_ONCE(sk->sk_mark);
526
527 res = ip_local_out(net, sk, skb);
528 rcu_read_unlock();
529 return res;
530
531 no_route:
532 rcu_read_unlock();
533 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
534 kfree_skb_reason(skb, SKB_DROP_REASON_IP_OUTNOROUTES);
535 return -EHOSTUNREACH;
536 }
537 EXPORT_SYMBOL(__ip_queue_xmit);
538
ip_queue_xmit(struct sock * sk,struct sk_buff * skb,struct flowi * fl)539 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
540 {
541 return __ip_queue_xmit(sk, skb, fl, READ_ONCE(inet_sk(sk)->tos));
542 }
543 EXPORT_SYMBOL(ip_queue_xmit);
544
ip_copy_metadata(struct sk_buff * to,struct sk_buff * from)545 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
546 {
547 to->pkt_type = from->pkt_type;
548 to->priority = from->priority;
549 to->protocol = from->protocol;
550 to->skb_iif = from->skb_iif;
551 skb_dst_drop(to);
552 skb_dst_copy(to, from);
553 to->dev = from->dev;
554 to->mark = from->mark;
555
556 skb_copy_hash(to, from);
557
558 #ifdef CONFIG_NET_SCHED
559 to->tc_index = from->tc_index;
560 #endif
561 nf_copy(to, from);
562 skb_ext_copy(to, from);
563 #if IS_ENABLED(CONFIG_IP_VS)
564 to->ipvs_property = from->ipvs_property;
565 #endif
566 skb_copy_secmark(to, from);
567 }
568
ip_fragment(struct net * net,struct sock * sk,struct sk_buff * skb,unsigned int mtu,int (* output)(struct net *,struct sock *,struct sk_buff *))569 static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
570 unsigned int mtu,
571 int (*output)(struct net *, struct sock *, struct sk_buff *))
572 {
573 struct iphdr *iph = ip_hdr(skb);
574
575 if ((iph->frag_off & htons(IP_DF)) == 0)
576 return ip_do_fragment(net, sk, skb, output);
577
578 if (unlikely(!skb->ignore_df ||
579 (IPCB(skb)->frag_max_size &&
580 IPCB(skb)->frag_max_size > mtu))) {
581 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
582 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
583 htonl(mtu));
584 kfree_skb(skb);
585 return -EMSGSIZE;
586 }
587
588 return ip_do_fragment(net, sk, skb, output);
589 }
590
ip_fraglist_init(struct sk_buff * skb,struct iphdr * iph,unsigned int hlen,struct ip_fraglist_iter * iter)591 void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
592 unsigned int hlen, struct ip_fraglist_iter *iter)
593 {
594 unsigned int first_len = skb_pagelen(skb);
595
596 iter->frag = skb_shinfo(skb)->frag_list;
597 skb_frag_list_init(skb);
598
599 iter->offset = 0;
600 iter->iph = iph;
601 iter->hlen = hlen;
602
603 skb->data_len = first_len - skb_headlen(skb);
604 skb->len = first_len;
605 iph->tot_len = htons(first_len);
606 iph->frag_off = htons(IP_MF);
607 ip_send_check(iph);
608 }
609 EXPORT_SYMBOL(ip_fraglist_init);
610
ip_fraglist_prepare(struct sk_buff * skb,struct ip_fraglist_iter * iter)611 void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
612 {
613 unsigned int hlen = iter->hlen;
614 struct iphdr *iph = iter->iph;
615 struct sk_buff *frag;
616
617 frag = iter->frag;
618 frag->ip_summed = CHECKSUM_NONE;
619 skb_reset_transport_header(frag);
620 __skb_push(frag, hlen);
621 skb_reset_network_header(frag);
622 memcpy(skb_network_header(frag), iph, hlen);
623 iter->iph = ip_hdr(frag);
624 iph = iter->iph;
625 iph->tot_len = htons(frag->len);
626 ip_copy_metadata(frag, skb);
627 iter->offset += skb->len - hlen;
628 iph->frag_off = htons(iter->offset >> 3);
629 if (frag->next)
630 iph->frag_off |= htons(IP_MF);
631 /* Ready, complete checksum */
632 ip_send_check(iph);
633 }
634 EXPORT_SYMBOL(ip_fraglist_prepare);
635
ip_frag_init(struct sk_buff * skb,unsigned int hlen,unsigned int ll_rs,unsigned int mtu,bool DF,struct ip_frag_state * state)636 void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
637 unsigned int ll_rs, unsigned int mtu, bool DF,
638 struct ip_frag_state *state)
639 {
640 struct iphdr *iph = ip_hdr(skb);
641
642 state->DF = DF;
643 state->hlen = hlen;
644 state->ll_rs = ll_rs;
645 state->mtu = mtu;
646
647 state->left = skb->len - hlen; /* Space per frame */
648 state->ptr = hlen; /* Where to start from */
649
650 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
651 state->not_last_frag = iph->frag_off & htons(IP_MF);
652 }
653 EXPORT_SYMBOL(ip_frag_init);
654
ip_frag_ipcb(struct sk_buff * from,struct sk_buff * to,bool first_frag)655 static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
656 bool first_frag)
657 {
658 /* Copy the flags to each fragment. */
659 IPCB(to)->flags = IPCB(from)->flags;
660
661 /* ANK: dirty, but effective trick. Upgrade options only if
662 * the segment to be fragmented was THE FIRST (otherwise,
663 * options are already fixed) and make it ONCE
664 * on the initial skb, so that all the following fragments
665 * will inherit fixed options.
666 */
667 if (first_frag)
668 ip_options_fragment(from);
669 }
670
ip_frag_next(struct sk_buff * skb,struct ip_frag_state * state)671 struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
672 {
673 unsigned int len = state->left;
674 struct sk_buff *skb2;
675 struct iphdr *iph;
676
677 /* IF: it doesn't fit, use 'mtu' - the data space left */
678 if (len > state->mtu)
679 len = state->mtu;
680 /* IF: we are not sending up to and including the packet end
681 then align the next start on an eight byte boundary */
682 if (len < state->left) {
683 len &= ~7;
684 }
685
686 /* Allocate buffer */
687 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
688 if (!skb2)
689 return ERR_PTR(-ENOMEM);
690
691 /*
692 * Set up data on packet
693 */
694
695 ip_copy_metadata(skb2, skb);
696 skb_reserve(skb2, state->ll_rs);
697 skb_put(skb2, len + state->hlen);
698 skb_reset_network_header(skb2);
699 skb2->transport_header = skb2->network_header + state->hlen;
700
701 /*
702 * Charge the memory for the fragment to any owner
703 * it might possess
704 */
705
706 if (skb->sk)
707 skb_set_owner_w(skb2, skb->sk);
708
709 /*
710 * Copy the packet header into the new buffer.
711 */
712
713 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
714
715 /*
716 * Copy a block of the IP datagram.
717 */
718 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
719 BUG();
720 state->left -= len;
721
722 /*
723 * Fill in the new header fields.
724 */
725 iph = ip_hdr(skb2);
726 iph->frag_off = htons((state->offset >> 3));
727 if (state->DF)
728 iph->frag_off |= htons(IP_DF);
729
730 /*
731 * Added AC : If we are fragmenting a fragment that's not the
732 * last fragment then keep MF on each bit
733 */
734 if (state->left > 0 || state->not_last_frag)
735 iph->frag_off |= htons(IP_MF);
736 state->ptr += len;
737 state->offset += len;
738
739 iph->tot_len = htons(len + state->hlen);
740
741 ip_send_check(iph);
742
743 return skb2;
744 }
745 EXPORT_SYMBOL(ip_frag_next);
746
747 /*
748 * This IP datagram is too large to be sent in one piece. Break it up into
749 * smaller pieces (each of size equal to IP header plus
750 * a block of the data of the original IP data part) that will yet fit in a
751 * single device frame, and queue such a frame for sending.
752 */
753
ip_do_fragment(struct net * net,struct sock * sk,struct sk_buff * skb,int (* output)(struct net *,struct sock *,struct sk_buff *))754 int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
755 int (*output)(struct net *, struct sock *, struct sk_buff *))
756 {
757 struct iphdr *iph;
758 struct sk_buff *skb2;
759 u8 tstamp_type = skb->tstamp_type;
760 struct rtable *rt = skb_rtable(skb);
761 unsigned int mtu, hlen, ll_rs;
762 struct ip_fraglist_iter iter;
763 ktime_t tstamp = skb->tstamp;
764 struct ip_frag_state state;
765 int err = 0;
766
767 /* for offloaded checksums cleanup checksum before fragmentation */
768 if (skb->ip_summed == CHECKSUM_PARTIAL &&
769 (err = skb_checksum_help(skb)))
770 goto fail;
771
772 /*
773 * Point into the IP datagram header.
774 */
775
776 iph = ip_hdr(skb);
777
778 mtu = ip_skb_dst_mtu(sk, skb);
779 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
780 mtu = IPCB(skb)->frag_max_size;
781
782 /*
783 * Setup starting values.
784 */
785
786 hlen = iph->ihl * 4;
787 mtu = mtu - hlen; /* Size of data space */
788 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
789 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
790
791 /* When frag_list is given, use it. First, check its validity:
792 * some transformers could create wrong frag_list or break existing
793 * one, it is not prohibited. In this case fall back to copying.
794 *
795 * LATER: this step can be merged to real generation of fragments,
796 * we can switch to copy when see the first bad fragment.
797 */
798 if (skb_has_frag_list(skb)) {
799 struct sk_buff *frag, *frag2;
800 unsigned int first_len = skb_pagelen(skb);
801
802 if (first_len - hlen > mtu ||
803 ((first_len - hlen) & 7) ||
804 ip_is_fragment(iph) ||
805 skb_cloned(skb) ||
806 skb_headroom(skb) < ll_rs)
807 goto slow_path;
808
809 skb_walk_frags(skb, frag) {
810 /* Correct geometry. */
811 if (frag->len > mtu ||
812 ((frag->len & 7) && frag->next) ||
813 skb_headroom(frag) < hlen + ll_rs)
814 goto slow_path_clean;
815
816 /* Partially cloned skb? */
817 if (skb_shared(frag))
818 goto slow_path_clean;
819
820 BUG_ON(frag->sk);
821 if (skb->sk) {
822 frag->sk = skb->sk;
823 frag->destructor = sock_wfree;
824 }
825 skb->truesize -= frag->truesize;
826 }
827
828 /* Everything is OK. Generate! */
829 ip_fraglist_init(skb, iph, hlen, &iter);
830
831 for (;;) {
832 /* Prepare header of the next frame,
833 * before previous one went down. */
834 if (iter.frag) {
835 bool first_frag = (iter.offset == 0);
836
837 IPCB(iter.frag)->flags = IPCB(skb)->flags;
838 ip_fraglist_prepare(skb, &iter);
839 if (first_frag && IPCB(skb)->opt.optlen) {
840 /* ipcb->opt is not populated for frags
841 * coming from __ip_make_skb(),
842 * ip_options_fragment() needs optlen
843 */
844 IPCB(iter.frag)->opt.optlen =
845 IPCB(skb)->opt.optlen;
846 ip_options_fragment(iter.frag);
847 ip_send_check(iter.iph);
848 }
849 }
850
851 skb_set_delivery_time(skb, tstamp, tstamp_type);
852 err = output(net, sk, skb);
853
854 if (!err)
855 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
856 if (err || !iter.frag)
857 break;
858
859 skb = ip_fraglist_next(&iter);
860 }
861
862 if (err == 0) {
863 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
864 return 0;
865 }
866
867 kfree_skb_list(iter.frag);
868
869 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
870 return err;
871
872 slow_path_clean:
873 skb_walk_frags(skb, frag2) {
874 if (frag2 == frag)
875 break;
876 frag2->sk = NULL;
877 frag2->destructor = NULL;
878 skb->truesize += frag2->truesize;
879 }
880 }
881
882 slow_path:
883 /*
884 * Fragment the datagram.
885 */
886
887 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
888 &state);
889
890 /*
891 * Keep copying data until we run out.
892 */
893
894 while (state.left > 0) {
895 bool first_frag = (state.offset == 0);
896
897 skb2 = ip_frag_next(skb, &state);
898 if (IS_ERR(skb2)) {
899 err = PTR_ERR(skb2);
900 goto fail;
901 }
902 ip_frag_ipcb(skb, skb2, first_frag);
903
904 /*
905 * Put this fragment into the sending queue.
906 */
907 skb_set_delivery_time(skb2, tstamp, tstamp_type);
908 err = output(net, sk, skb2);
909 if (err)
910 goto fail;
911
912 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
913 }
914 consume_skb(skb);
915 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
916 return err;
917
918 fail:
919 kfree_skb(skb);
920 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
921 return err;
922 }
923 EXPORT_SYMBOL(ip_do_fragment);
924
925 int
ip_generic_getfrag(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)926 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
927 {
928 struct msghdr *msg = from;
929
930 if (skb->ip_summed == CHECKSUM_PARTIAL) {
931 if (!copy_from_iter_full(to, len, &msg->msg_iter))
932 return -EFAULT;
933 } else {
934 __wsum csum = 0;
935 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
936 return -EFAULT;
937 skb->csum = csum_block_add(skb->csum, csum, odd);
938 }
939 return 0;
940 }
941 EXPORT_SYMBOL(ip_generic_getfrag);
942
__ip_append_data(struct sock * sk,struct flowi4 * fl4,struct sk_buff_head * queue,struct inet_cork * cork,struct page_frag * pfrag,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)943 static int __ip_append_data(struct sock *sk,
944 struct flowi4 *fl4,
945 struct sk_buff_head *queue,
946 struct inet_cork *cork,
947 struct page_frag *pfrag,
948 int getfrag(void *from, char *to, int offset,
949 int len, int odd, struct sk_buff *skb),
950 void *from, int length, int transhdrlen,
951 unsigned int flags)
952 {
953 struct inet_sock *inet = inet_sk(sk);
954 struct ubuf_info *uarg = NULL;
955 struct sk_buff *skb;
956 struct ip_options *opt = cork->opt;
957 int hh_len;
958 int exthdrlen;
959 int mtu;
960 int copy;
961 int err;
962 int offset = 0;
963 bool zc = false;
964 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
965 int csummode = CHECKSUM_NONE;
966 struct rtable *rt = dst_rtable(cork->dst);
967 bool paged, hold_tskey = false, extra_uref = false;
968 unsigned int wmem_alloc_delta = 0;
969 u32 tskey = 0;
970
971 skb = skb_peek_tail(queue);
972
973 exthdrlen = !skb ? rt->dst.header_len : 0;
974 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
975 paged = !!cork->gso_size;
976
977 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
978
979 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
980 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
981 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu;
982
983 if (cork->length + length > maxnonfragsize - fragheaderlen) {
984 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
985 mtu - (opt ? opt->optlen : 0));
986 return -EMSGSIZE;
987 }
988
989 /*
990 * transhdrlen > 0 means that this is the first fragment and we wish
991 * it won't be fragmented in the future.
992 */
993 if (transhdrlen &&
994 length + fragheaderlen <= mtu &&
995 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
996 (!(flags & MSG_MORE) || cork->gso_size) &&
997 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
998 csummode = CHECKSUM_PARTIAL;
999
1000 if ((flags & MSG_ZEROCOPY) && length) {
1001 struct msghdr *msg = from;
1002
1003 if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
1004 if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb))
1005 return -EINVAL;
1006
1007 /* Leave uarg NULL if can't zerocopy, callers should
1008 * be able to handle it.
1009 */
1010 if ((rt->dst.dev->features & NETIF_F_SG) &&
1011 csummode == CHECKSUM_PARTIAL) {
1012 paged = true;
1013 zc = true;
1014 uarg = msg->msg_ubuf;
1015 }
1016 } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
1017 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
1018 if (!uarg)
1019 return -ENOBUFS;
1020 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
1021 if (rt->dst.dev->features & NETIF_F_SG &&
1022 csummode == CHECKSUM_PARTIAL) {
1023 paged = true;
1024 zc = true;
1025 } else {
1026 uarg_to_msgzc(uarg)->zerocopy = 0;
1027 skb_zcopy_set(skb, uarg, &extra_uref);
1028 }
1029 }
1030 } else if ((flags & MSG_SPLICE_PAGES) && length) {
1031 if (inet_test_bit(HDRINCL, sk))
1032 return -EPERM;
1033 if (rt->dst.dev->features & NETIF_F_SG &&
1034 getfrag == ip_generic_getfrag)
1035 /* We need an empty buffer to attach stuff to */
1036 paged = true;
1037 else
1038 flags &= ~MSG_SPLICE_PAGES;
1039 }
1040
1041 cork->length += length;
1042
1043 if (cork->tx_flags & SKBTX_ANY_TSTAMP &&
1044 READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
1045 if (cork->flags & IPCORK_TS_OPT_ID) {
1046 tskey = cork->ts_opt_id;
1047 } else {
1048 tskey = atomic_inc_return(&sk->sk_tskey) - 1;
1049 hold_tskey = true;
1050 }
1051 }
1052
1053 /* So, what's going on in the loop below?
1054 *
1055 * We use calculated fragment length to generate chained skb,
1056 * each of segments is IP fragment ready for sending to network after
1057 * adding appropriate IP header.
1058 */
1059
1060 if (!skb)
1061 goto alloc_new_skb;
1062
1063 while (length > 0) {
1064 /* Check if the remaining data fits into current packet. */
1065 copy = mtu - skb->len;
1066 if (copy < length)
1067 copy = maxfraglen - skb->len;
1068 if (copy <= 0) {
1069 char *data;
1070 unsigned int datalen;
1071 unsigned int fraglen;
1072 unsigned int fraggap;
1073 unsigned int alloclen, alloc_extra;
1074 unsigned int pagedlen;
1075 struct sk_buff *skb_prev;
1076 alloc_new_skb:
1077 skb_prev = skb;
1078 if (skb_prev)
1079 fraggap = skb_prev->len - maxfraglen;
1080 else
1081 fraggap = 0;
1082
1083 /*
1084 * If remaining data exceeds the mtu,
1085 * we know we need more fragment(s).
1086 */
1087 datalen = length + fraggap;
1088 if (datalen > mtu - fragheaderlen)
1089 datalen = maxfraglen - fragheaderlen;
1090 fraglen = datalen + fragheaderlen;
1091 pagedlen = 0;
1092
1093 alloc_extra = hh_len + 15;
1094 alloc_extra += exthdrlen;
1095
1096 /* The last fragment gets additional space at tail.
1097 * Note, with MSG_MORE we overallocate on fragments,
1098 * because we have no idea what fragment will be
1099 * the last.
1100 */
1101 if (datalen == length + fraggap)
1102 alloc_extra += rt->dst.trailer_len;
1103
1104 if ((flags & MSG_MORE) &&
1105 !(rt->dst.dev->features&NETIF_F_SG))
1106 alloclen = mtu;
1107 else if (!paged &&
1108 (fraglen + alloc_extra < SKB_MAX_ALLOC ||
1109 !(rt->dst.dev->features & NETIF_F_SG)))
1110 alloclen = fraglen;
1111 else {
1112 alloclen = fragheaderlen + transhdrlen;
1113 pagedlen = datalen - transhdrlen;
1114 }
1115
1116 alloclen += alloc_extra;
1117
1118 if (transhdrlen) {
1119 skb = sock_alloc_send_skb(sk, alloclen,
1120 (flags & MSG_DONTWAIT), &err);
1121 } else {
1122 skb = NULL;
1123 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1124 2 * sk->sk_sndbuf)
1125 skb = alloc_skb(alloclen,
1126 sk->sk_allocation);
1127 if (unlikely(!skb))
1128 err = -ENOBUFS;
1129 }
1130 if (!skb)
1131 goto error;
1132
1133 /*
1134 * Fill in the control structures
1135 */
1136 skb->ip_summed = csummode;
1137 skb->csum = 0;
1138 skb_reserve(skb, hh_len);
1139
1140 /*
1141 * Find where to start putting bytes.
1142 */
1143 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1144 skb_set_network_header(skb, exthdrlen);
1145 skb->transport_header = (skb->network_header +
1146 fragheaderlen);
1147 data += fragheaderlen + exthdrlen;
1148
1149 if (fraggap) {
1150 skb->csum = skb_copy_and_csum_bits(
1151 skb_prev, maxfraglen,
1152 data + transhdrlen, fraggap);
1153 skb_prev->csum = csum_sub(skb_prev->csum,
1154 skb->csum);
1155 data += fraggap;
1156 pskb_trim_unique(skb_prev, maxfraglen);
1157 }
1158
1159 copy = datalen - transhdrlen - fraggap - pagedlen;
1160 /* [!] NOTE: copy will be negative if pagedlen>0
1161 * because then the equation reduces to -fraggap.
1162 */
1163 if (copy > 0 &&
1164 INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
1165 from, data + transhdrlen, offset,
1166 copy, fraggap, skb) < 0) {
1167 err = -EFAULT;
1168 kfree_skb(skb);
1169 goto error;
1170 } else if (flags & MSG_SPLICE_PAGES) {
1171 copy = 0;
1172 }
1173
1174 offset += copy;
1175 length -= copy + transhdrlen;
1176 transhdrlen = 0;
1177 exthdrlen = 0;
1178 csummode = CHECKSUM_NONE;
1179
1180 /* only the initial fragment is time stamped */
1181 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1182 cork->tx_flags = 0;
1183 skb_shinfo(skb)->tskey = tskey;
1184 tskey = 0;
1185 skb_zcopy_set(skb, uarg, &extra_uref);
1186
1187 if ((flags & MSG_CONFIRM) && !skb_prev)
1188 skb_set_dst_pending_confirm(skb, 1);
1189
1190 /*
1191 * Put the packet on the pending queue.
1192 */
1193 if (!skb->destructor) {
1194 skb->destructor = sock_wfree;
1195 skb->sk = sk;
1196 wmem_alloc_delta += skb->truesize;
1197 }
1198 __skb_queue_tail(queue, skb);
1199 continue;
1200 }
1201
1202 if (copy > length)
1203 copy = length;
1204
1205 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1206 skb_tailroom(skb) >= copy) {
1207 unsigned int off;
1208
1209 off = skb->len;
1210 if (INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
1211 from, skb_put(skb, copy),
1212 offset, copy, off, skb) < 0) {
1213 __skb_trim(skb, off);
1214 err = -EFAULT;
1215 goto error;
1216 }
1217 } else if (flags & MSG_SPLICE_PAGES) {
1218 struct msghdr *msg = from;
1219
1220 err = -EIO;
1221 if (WARN_ON_ONCE(copy > msg->msg_iter.count))
1222 goto error;
1223
1224 err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
1225 sk->sk_allocation);
1226 if (err < 0)
1227 goto error;
1228 copy = err;
1229 wmem_alloc_delta += copy;
1230 } else if (!zc) {
1231 int i = skb_shinfo(skb)->nr_frags;
1232
1233 err = -ENOMEM;
1234 if (!sk_page_frag_refill(sk, pfrag))
1235 goto error;
1236
1237 skb_zcopy_downgrade_managed(skb);
1238 if (!skb_can_coalesce(skb, i, pfrag->page,
1239 pfrag->offset)) {
1240 err = -EMSGSIZE;
1241 if (i == MAX_SKB_FRAGS)
1242 goto error;
1243
1244 __skb_fill_page_desc(skb, i, pfrag->page,
1245 pfrag->offset, 0);
1246 skb_shinfo(skb)->nr_frags = ++i;
1247 get_page(pfrag->page);
1248 }
1249 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1250 if (INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
1251 from,
1252 page_address(pfrag->page) + pfrag->offset,
1253 offset, copy, skb->len, skb) < 0)
1254 goto error_efault;
1255
1256 pfrag->offset += copy;
1257 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1258 skb_len_add(skb, copy);
1259 wmem_alloc_delta += copy;
1260 } else {
1261 err = skb_zerocopy_iter_dgram(skb, from, copy);
1262 if (err < 0)
1263 goto error;
1264 }
1265 offset += copy;
1266 length -= copy;
1267 }
1268
1269 if (wmem_alloc_delta)
1270 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1271 return 0;
1272
1273 error_efault:
1274 err = -EFAULT;
1275 error:
1276 net_zcopy_put_abort(uarg, extra_uref);
1277 cork->length -= length;
1278 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1279 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1280 if (hold_tskey)
1281 atomic_dec(&sk->sk_tskey);
1282 return err;
1283 }
1284
ip_setup_cork(struct sock * sk,struct inet_cork * cork,struct ipcm_cookie * ipc,struct rtable ** rtp)1285 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1286 struct ipcm_cookie *ipc, struct rtable **rtp)
1287 {
1288 struct ip_options_rcu *opt;
1289 struct rtable *rt;
1290
1291 rt = *rtp;
1292 if (unlikely(!rt))
1293 return -EFAULT;
1294
1295 cork->fragsize = ip_sk_use_pmtu(sk) ?
1296 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
1297
1298 if (!inetdev_valid_mtu(cork->fragsize))
1299 return -ENETUNREACH;
1300
1301 /*
1302 * setup for corking.
1303 */
1304 opt = ipc->opt;
1305 if (opt) {
1306 if (!cork->opt) {
1307 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1308 sk->sk_allocation);
1309 if (unlikely(!cork->opt))
1310 return -ENOBUFS;
1311 }
1312 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1313 cork->flags |= IPCORK_OPT;
1314 cork->addr = ipc->addr;
1315 }
1316
1317 cork->gso_size = ipc->gso_size;
1318
1319 cork->dst = &rt->dst;
1320 /* We stole this route, caller should not release it. */
1321 *rtp = NULL;
1322
1323 cork->length = 0;
1324 cork->ttl = ipc->ttl;
1325 cork->tos = ipc->tos;
1326 cork->mark = ipc->sockc.mark;
1327 cork->priority = ipc->sockc.priority;
1328 cork->transmit_time = ipc->sockc.transmit_time;
1329 cork->tx_flags = 0;
1330 sock_tx_timestamp(sk, &ipc->sockc, &cork->tx_flags);
1331 if (ipc->sockc.tsflags & SOCKCM_FLAG_TS_OPT_ID) {
1332 cork->flags |= IPCORK_TS_OPT_ID;
1333 cork->ts_opt_id = ipc->sockc.ts_opt_id;
1334 }
1335
1336 return 0;
1337 }
1338
1339 /*
1340 * ip_append_data() can make one large IP datagram from many pieces of
1341 * data. Each piece will be held on the socket until
1342 * ip_push_pending_frames() is called. Each piece can be a page or
1343 * non-page data.
1344 *
1345 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1346 * this interface potentially.
1347 *
1348 * LATER: length must be adjusted by pad at tail, when it is required.
1349 */
ip_append_data(struct sock * sk,struct flowi4 * fl4,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)1350 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1351 int getfrag(void *from, char *to, int offset, int len,
1352 int odd, struct sk_buff *skb),
1353 void *from, int length, int transhdrlen,
1354 struct ipcm_cookie *ipc, struct rtable **rtp,
1355 unsigned int flags)
1356 {
1357 struct inet_sock *inet = inet_sk(sk);
1358 int err;
1359
1360 if (flags&MSG_PROBE)
1361 return 0;
1362
1363 if (skb_queue_empty(&sk->sk_write_queue)) {
1364 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1365 if (err)
1366 return err;
1367 } else {
1368 transhdrlen = 0;
1369 }
1370
1371 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1372 sk_page_frag(sk), getfrag,
1373 from, length, transhdrlen, flags);
1374 }
1375
ip_cork_release(struct inet_cork * cork)1376 static void ip_cork_release(struct inet_cork *cork)
1377 {
1378 cork->flags &= ~IPCORK_OPT;
1379 kfree(cork->opt);
1380 cork->opt = NULL;
1381 dst_release(cork->dst);
1382 cork->dst = NULL;
1383 }
1384
1385 /*
1386 * Combined all pending IP fragments on the socket as one IP datagram
1387 * and push them out.
1388 */
__ip_make_skb(struct sock * sk,struct flowi4 * fl4,struct sk_buff_head * queue,struct inet_cork * cork)1389 struct sk_buff *__ip_make_skb(struct sock *sk,
1390 struct flowi4 *fl4,
1391 struct sk_buff_head *queue,
1392 struct inet_cork *cork)
1393 {
1394 struct sk_buff *skb, *tmp_skb;
1395 struct sk_buff **tail_skb;
1396 struct inet_sock *inet = inet_sk(sk);
1397 struct net *net = sock_net(sk);
1398 struct ip_options *opt = NULL;
1399 struct rtable *rt = dst_rtable(cork->dst);
1400 struct iphdr *iph;
1401 u8 pmtudisc, ttl;
1402 __be16 df = 0;
1403
1404 skb = __skb_dequeue(queue);
1405 if (!skb)
1406 goto out;
1407 tail_skb = &(skb_shinfo(skb)->frag_list);
1408
1409 /* move skb->data to ip header from ext header */
1410 if (skb->data < skb_network_header(skb))
1411 __skb_pull(skb, skb_network_offset(skb));
1412 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1413 __skb_pull(tmp_skb, skb_network_header_len(skb));
1414 *tail_skb = tmp_skb;
1415 tail_skb = &(tmp_skb->next);
1416 skb->len += tmp_skb->len;
1417 skb->data_len += tmp_skb->len;
1418 skb->truesize += tmp_skb->truesize;
1419 tmp_skb->destructor = NULL;
1420 tmp_skb->sk = NULL;
1421 }
1422
1423 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1424 * to fragment the frame generated here. No matter, what transforms
1425 * how transforms change size of the packet, it will come out.
1426 */
1427 skb->ignore_df = ip_sk_ignore_df(sk);
1428
1429 /* DF bit is set when we want to see DF on outgoing frames.
1430 * If ignore_df is set too, we still allow to fragment this frame
1431 * locally. */
1432 pmtudisc = READ_ONCE(inet->pmtudisc);
1433 if (pmtudisc == IP_PMTUDISC_DO ||
1434 pmtudisc == IP_PMTUDISC_PROBE ||
1435 (skb->len <= dst_mtu(&rt->dst) &&
1436 ip_dont_fragment(sk, &rt->dst)))
1437 df = htons(IP_DF);
1438
1439 if (cork->flags & IPCORK_OPT)
1440 opt = cork->opt;
1441
1442 if (cork->ttl != 0)
1443 ttl = cork->ttl;
1444 else if (rt->rt_type == RTN_MULTICAST)
1445 ttl = READ_ONCE(inet->mc_ttl);
1446 else
1447 ttl = ip_select_ttl(inet, &rt->dst);
1448
1449 iph = ip_hdr(skb);
1450 iph->version = 4;
1451 iph->ihl = 5;
1452 iph->tos = (cork->tos != -1) ? cork->tos : READ_ONCE(inet->tos);
1453 iph->frag_off = df;
1454 iph->ttl = ttl;
1455 iph->protocol = sk->sk_protocol;
1456 ip_copy_addrs(iph, fl4);
1457 ip_select_ident(net, skb, sk);
1458
1459 if (opt) {
1460 iph->ihl += opt->optlen >> 2;
1461 ip_options_build(skb, opt, cork->addr, rt);
1462 }
1463
1464 skb->priority = cork->priority;
1465 skb->mark = cork->mark;
1466 if (sk_is_tcp(sk))
1467 skb_set_delivery_time(skb, cork->transmit_time, SKB_CLOCK_MONOTONIC);
1468 else
1469 skb_set_delivery_type_by_clockid(skb, cork->transmit_time, sk->sk_clockid);
1470 /*
1471 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1472 * on dst refcount
1473 */
1474 cork->dst = NULL;
1475 skb_dst_set(skb, &rt->dst);
1476
1477 if (iph->protocol == IPPROTO_ICMP) {
1478 u8 icmp_type;
1479
1480 /* For such sockets, transhdrlen is zero when do ip_append_data(),
1481 * so icmphdr does not in skb linear region and can not get icmp_type
1482 * by icmp_hdr(skb)->type.
1483 */
1484 if (sk->sk_type == SOCK_RAW &&
1485 !(fl4->flowi4_flags & FLOWI_FLAG_KNOWN_NH))
1486 icmp_type = fl4->fl4_icmp_type;
1487 else
1488 icmp_type = icmp_hdr(skb)->type;
1489 icmp_out_count(net, icmp_type);
1490 }
1491
1492 ip_cork_release(cork);
1493 out:
1494 return skb;
1495 }
1496
ip_send_skb(struct net * net,struct sk_buff * skb)1497 int ip_send_skb(struct net *net, struct sk_buff *skb)
1498 {
1499 int err;
1500
1501 err = ip_local_out(net, skb->sk, skb);
1502 if (err) {
1503 if (err > 0)
1504 err = net_xmit_errno(err);
1505 if (err)
1506 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1507 }
1508
1509 return err;
1510 }
1511
ip_push_pending_frames(struct sock * sk,struct flowi4 * fl4)1512 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1513 {
1514 struct sk_buff *skb;
1515
1516 skb = ip_finish_skb(sk, fl4);
1517 if (!skb)
1518 return 0;
1519
1520 /* Netfilter gets whole the not fragmented skb. */
1521 return ip_send_skb(sock_net(sk), skb);
1522 }
1523
1524 /*
1525 * Throw away all pending data on the socket.
1526 */
__ip_flush_pending_frames(struct sock * sk,struct sk_buff_head * queue,struct inet_cork * cork)1527 static void __ip_flush_pending_frames(struct sock *sk,
1528 struct sk_buff_head *queue,
1529 struct inet_cork *cork)
1530 {
1531 struct sk_buff *skb;
1532
1533 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1534 kfree_skb(skb);
1535
1536 ip_cork_release(cork);
1537 }
1538
ip_flush_pending_frames(struct sock * sk)1539 void ip_flush_pending_frames(struct sock *sk)
1540 {
1541 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1542 }
1543
ip_make_skb(struct sock * sk,struct flowi4 * fl4,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,struct inet_cork * cork,unsigned int flags)1544 struct sk_buff *ip_make_skb(struct sock *sk,
1545 struct flowi4 *fl4,
1546 int getfrag(void *from, char *to, int offset,
1547 int len, int odd, struct sk_buff *skb),
1548 void *from, int length, int transhdrlen,
1549 struct ipcm_cookie *ipc, struct rtable **rtp,
1550 struct inet_cork *cork, unsigned int flags)
1551 {
1552 struct sk_buff_head queue;
1553 int err;
1554
1555 if (flags & MSG_PROBE)
1556 return NULL;
1557
1558 __skb_queue_head_init(&queue);
1559
1560 cork->flags = 0;
1561 cork->addr = 0;
1562 cork->opt = NULL;
1563 err = ip_setup_cork(sk, cork, ipc, rtp);
1564 if (err)
1565 return ERR_PTR(err);
1566
1567 err = __ip_append_data(sk, fl4, &queue, cork,
1568 ¤t->task_frag, getfrag,
1569 from, length, transhdrlen, flags);
1570 if (err) {
1571 __ip_flush_pending_frames(sk, &queue, cork);
1572 return ERR_PTR(err);
1573 }
1574
1575 return __ip_make_skb(sk, fl4, &queue, cork);
1576 }
1577
1578 /*
1579 * Fetch data from kernel space and fill in checksum if needed.
1580 */
ip_reply_glue_bits(void * dptr,char * to,int offset,int len,int odd,struct sk_buff * skb)1581 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1582 int len, int odd, struct sk_buff *skb)
1583 {
1584 __wsum csum;
1585
1586 csum = csum_partial_copy_nocheck(dptr+offset, to, len);
1587 skb->csum = csum_block_add(skb->csum, csum, odd);
1588 return 0;
1589 }
1590
1591 /*
1592 * Generic function to send a packet as reply to another packet.
1593 * Used to send some TCP resets/acks so far.
1594 */
ip_send_unicast_reply(struct sock * sk,const struct sock * orig_sk,struct sk_buff * skb,const struct ip_options * sopt,__be32 daddr,__be32 saddr,const struct ip_reply_arg * arg,unsigned int len,u64 transmit_time,u32 txhash)1595 void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
1596 struct sk_buff *skb,
1597 const struct ip_options *sopt,
1598 __be32 daddr, __be32 saddr,
1599 const struct ip_reply_arg *arg,
1600 unsigned int len, u64 transmit_time, u32 txhash)
1601 {
1602 struct ip_options_data replyopts;
1603 struct ipcm_cookie ipc;
1604 struct flowi4 fl4;
1605 struct rtable *rt = skb_rtable(skb);
1606 struct net *net = sock_net(sk);
1607 struct sk_buff *nskb;
1608 int err;
1609 int oif;
1610
1611 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1612 return;
1613
1614 ipcm_init(&ipc);
1615 ipc.addr = daddr;
1616 ipc.sockc.transmit_time = transmit_time;
1617
1618 if (replyopts.opt.opt.optlen) {
1619 ipc.opt = &replyopts.opt;
1620
1621 if (replyopts.opt.opt.srr)
1622 daddr = replyopts.opt.opt.faddr;
1623 }
1624
1625 oif = arg->bound_dev_if;
1626 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1627 oif = skb->skb_iif;
1628
1629 flowi4_init_output(&fl4, oif,
1630 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1631 arg->tos & INET_DSCP_MASK,
1632 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1633 ip_reply_arg_flowi_flags(arg),
1634 daddr, saddr,
1635 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1636 arg->uid);
1637 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
1638 rt = ip_route_output_flow(net, &fl4, sk);
1639 if (IS_ERR(rt))
1640 return;
1641
1642 inet_sk(sk)->tos = arg->tos;
1643
1644 sk->sk_protocol = ip_hdr(skb)->protocol;
1645 sk->sk_bound_dev_if = arg->bound_dev_if;
1646 sk->sk_sndbuf = READ_ONCE(sysctl_wmem_default);
1647 ipc.sockc.mark = fl4.flowi4_mark;
1648 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1649 len, 0, &ipc, &rt, MSG_DONTWAIT);
1650 if (unlikely(err)) {
1651 ip_flush_pending_frames(sk);
1652 goto out;
1653 }
1654
1655 nskb = skb_peek(&sk->sk_write_queue);
1656 if (nskb) {
1657 if (arg->csumoffset >= 0)
1658 *((__sum16 *)skb_transport_header(nskb) +
1659 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1660 arg->csum));
1661 nskb->ip_summed = CHECKSUM_NONE;
1662 if (orig_sk)
1663 skb_set_owner_edemux(nskb, (struct sock *)orig_sk);
1664 if (transmit_time)
1665 nskb->tstamp_type = SKB_CLOCK_MONOTONIC;
1666 if (txhash)
1667 skb_set_hash(nskb, txhash, PKT_HASH_TYPE_L4);
1668 ip_push_pending_frames(sk, &fl4);
1669 }
1670 out:
1671 ip_rt_put(rt);
1672 }
1673
ip_init(void)1674 void __init ip_init(void)
1675 {
1676 ip_rt_init();
1677 inet_initpeers();
1678
1679 #if defined(CONFIG_IP_MULTICAST)
1680 igmp_mc_init();
1681 #endif
1682 }
1683