V4L/DVB (6812): media: video: usbvision: remove ctrlUrbLock
[pv_ops_mirror.git] / net / ipv4 / ip_output.c
blobbc9e57550e86d9b4f5b9ee965466f3d4f52f2585
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.
6 * The Internet Protocol (IP) output module.
8 * Version: $Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Donald Becker, <becker@super.org>
13 * Alan Cox, <Alan.Cox@linux.org>
14 * Richard Underwood
15 * Stefan Becker, <stefanb@yello.ping.de>
16 * Jorge Cwik, <jorge@laser.satlink.net>
17 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
18 * Hirokazu Takahashi, <taka@valinux.co.jp>
20 * See ip_input.c for original log
22 * Fixes:
23 * Alan Cox : Missing nonblock feature in ip_build_xmit.
24 * Mike Kilburn : htons() missing in ip_build_xmit.
25 * Bradford Johnson: Fix faulty handling of some frames when
26 * no route is found.
27 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
28 * (in case if packet not accepted by
29 * output firewall rules)
30 * Mike McLagan : Routing by source
31 * Alexey Kuznetsov: use new route cache
32 * Andi Kleen: Fix broken PMTU recovery and remove
33 * some redundant tests.
34 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
35 * Andi Kleen : Replace ip_reply with ip_send_reply.
36 * Andi Kleen : Split fast and slow ip_build_xmit path
37 * for decreased register pressure on x86
38 * and more readibility.
39 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
40 * silently drop skb instead of failing with -EPERM.
41 * Detlev Wengorz : Copy protocol for fragments.
42 * Hirokazu Takahashi: HW checksumming for outgoing UDP
43 * datagrams.
44 * Hirokazu Takahashi: sendfile() on UDP works now.
47 #include <asm/uaccess.h>
48 #include <asm/system.h>
49 #include <linux/module.h>
50 #include <linux/types.h>
51 #include <linux/kernel.h>
52 #include <linux/mm.h>
53 #include <linux/string.h>
54 #include <linux/errno.h>
55 #include <linux/highmem.h>
57 #include <linux/socket.h>
58 #include <linux/sockios.h>
59 #include <linux/in.h>
60 #include <linux/inet.h>
61 #include <linux/netdevice.h>
62 #include <linux/etherdevice.h>
63 #include <linux/proc_fs.h>
64 #include <linux/stat.h>
65 #include <linux/init.h>
67 #include <net/snmp.h>
68 #include <net/ip.h>
69 #include <net/protocol.h>
70 #include <net/route.h>
71 #include <net/xfrm.h>
72 #include <linux/skbuff.h>
73 #include <net/sock.h>
74 #include <net/arp.h>
75 #include <net/icmp.h>
76 #include <net/checksum.h>
77 #include <net/inetpeer.h>
78 #include <linux/igmp.h>
79 #include <linux/netfilter_ipv4.h>
80 #include <linux/netfilter_bridge.h>
81 #include <linux/mroute.h>
82 #include <linux/netlink.h>
83 #include <linux/tcp.h>
85 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
87 /* Generate a checksum for an outgoing IP datagram. */
88 __inline__ void ip_send_check(struct iphdr *iph)
90 iph->check = 0;
91 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
94 /* dev_loopback_xmit for use with netfilter. */
95 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
97 skb_reset_mac_header(newskb);
98 __skb_pull(newskb, skb_network_offset(newskb));
99 newskb->pkt_type = PACKET_LOOPBACK;
100 newskb->ip_summed = CHECKSUM_UNNECESSARY;
101 BUG_TRAP(newskb->dst);
102 netif_rx(newskb);
103 return 0;
106 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
108 int ttl = inet->uc_ttl;
110 if (ttl < 0)
111 ttl = dst_metric(dst, RTAX_HOPLIMIT);
112 return ttl;
116 * Add an ip header to a skbuff and send it out.
119 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
120 __be32 saddr, __be32 daddr, struct ip_options *opt)
122 struct inet_sock *inet = inet_sk(sk);
123 struct rtable *rt = (struct rtable *)skb->dst;
124 struct iphdr *iph;
126 /* Build the IP header. */
127 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
128 skb_reset_network_header(skb);
129 iph = ip_hdr(skb);
130 iph->version = 4;
131 iph->ihl = 5;
132 iph->tos = inet->tos;
133 if (ip_dont_fragment(sk, &rt->u.dst))
134 iph->frag_off = htons(IP_DF);
135 else
136 iph->frag_off = 0;
137 iph->ttl = ip_select_ttl(inet, &rt->u.dst);
138 iph->daddr = rt->rt_dst;
139 iph->saddr = rt->rt_src;
140 iph->protocol = sk->sk_protocol;
141 iph->tot_len = htons(skb->len);
142 ip_select_ident(iph, &rt->u.dst, sk);
144 if (opt && opt->optlen) {
145 iph->ihl += opt->optlen>>2;
146 ip_options_build(skb, opt, daddr, rt, 0);
148 ip_send_check(iph);
150 skb->priority = sk->sk_priority;
152 /* Send it out. */
153 return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
154 dst_output);
157 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
159 static inline int ip_finish_output2(struct sk_buff *skb)
161 struct dst_entry *dst = skb->dst;
162 struct rtable *rt = (struct rtable *)dst;
163 struct net_device *dev = dst->dev;
164 unsigned int hh_len = LL_RESERVED_SPACE(dev);
166 if (rt->rt_type == RTN_MULTICAST)
167 IP_INC_STATS(IPSTATS_MIB_OUTMCASTPKTS);
168 else if (rt->rt_type == RTN_BROADCAST)
169 IP_INC_STATS(IPSTATS_MIB_OUTBCASTPKTS);
171 /* Be paranoid, rather than too clever. */
172 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
173 struct sk_buff *skb2;
175 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
176 if (skb2 == NULL) {
177 kfree_skb(skb);
178 return -ENOMEM;
180 if (skb->sk)
181 skb_set_owner_w(skb2, skb->sk);
182 kfree_skb(skb);
183 skb = skb2;
186 if (dst->hh)
187 return neigh_hh_output(dst->hh, skb);
188 else if (dst->neighbour)
189 return dst->neighbour->output(skb);
191 if (net_ratelimit())
192 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
193 kfree_skb(skb);
194 return -EINVAL;
197 static inline int ip_skb_dst_mtu(struct sk_buff *skb)
199 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
201 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
202 skb->dst->dev->mtu : dst_mtu(skb->dst);
205 static int ip_finish_output(struct sk_buff *skb)
207 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
208 /* Policy lookup after SNAT yielded a new policy */
209 if (skb->dst->xfrm != NULL) {
210 IPCB(skb)->flags |= IPSKB_REROUTED;
211 return dst_output(skb);
213 #endif
214 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
215 return ip_fragment(skb, ip_finish_output2);
216 else
217 return ip_finish_output2(skb);
220 int ip_mc_output(struct sk_buff *skb)
222 struct sock *sk = skb->sk;
223 struct rtable *rt = (struct rtable*)skb->dst;
224 struct net_device *dev = rt->u.dst.dev;
227 * If the indicated interface is up and running, send the packet.
229 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
231 skb->dev = dev;
232 skb->protocol = htons(ETH_P_IP);
235 * Multicasts are looped back for other local users
238 if (rt->rt_flags&RTCF_MULTICAST) {
239 if ((!sk || inet_sk(sk)->mc_loop)
240 #ifdef CONFIG_IP_MROUTE
241 /* Small optimization: do not loopback not local frames,
242 which returned after forwarding; they will be dropped
243 by ip_mr_input in any case.
244 Note, that local frames are looped back to be delivered
245 to local recipients.
247 This check is duplicated in ip_mr_input at the moment.
249 && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
250 #endif
252 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
253 if (newskb)
254 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
255 newskb->dev,
256 ip_dev_loopback_xmit);
259 /* Multicasts with ttl 0 must not go beyond the host */
261 if (ip_hdr(skb)->ttl == 0) {
262 kfree_skb(skb);
263 return 0;
267 if (rt->rt_flags&RTCF_BROADCAST) {
268 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
269 if (newskb)
270 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
271 newskb->dev, ip_dev_loopback_xmit);
274 return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev,
275 ip_finish_output,
276 !(IPCB(skb)->flags & IPSKB_REROUTED));
279 int ip_output(struct sk_buff *skb)
281 struct net_device *dev = skb->dst->dev;
283 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
285 skb->dev = dev;
286 skb->protocol = htons(ETH_P_IP);
288 return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
289 ip_finish_output,
290 !(IPCB(skb)->flags & IPSKB_REROUTED));
293 int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
295 struct sock *sk = skb->sk;
296 struct inet_sock *inet = inet_sk(sk);
297 struct ip_options *opt = inet->opt;
298 struct rtable *rt;
299 struct iphdr *iph;
301 /* Skip all of this if the packet is already routed,
302 * f.e. by something like SCTP.
304 rt = (struct rtable *) skb->dst;
305 if (rt != NULL)
306 goto packet_routed;
308 /* Make sure we can route this packet. */
309 rt = (struct rtable *)__sk_dst_check(sk, 0);
310 if (rt == NULL) {
311 __be32 daddr;
313 /* Use correct destination address if we have options. */
314 daddr = inet->daddr;
315 if(opt && opt->srr)
316 daddr = opt->faddr;
319 struct flowi fl = { .oif = sk->sk_bound_dev_if,
320 .nl_u = { .ip4_u =
321 { .daddr = daddr,
322 .saddr = inet->saddr,
323 .tos = RT_CONN_FLAGS(sk) } },
324 .proto = sk->sk_protocol,
325 .uli_u = { .ports =
326 { .sport = inet->sport,
327 .dport = inet->dport } } };
329 /* If this fails, retransmit mechanism of transport layer will
330 * keep trying until route appears or the connection times
331 * itself out.
333 security_sk_classify_flow(sk, &fl);
334 if (ip_route_output_flow(&rt, &fl, sk, 0))
335 goto no_route;
337 sk_setup_caps(sk, &rt->u.dst);
339 skb->dst = dst_clone(&rt->u.dst);
341 packet_routed:
342 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
343 goto no_route;
345 /* OK, we know where to send it, allocate and build IP header. */
346 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
347 skb_reset_network_header(skb);
348 iph = ip_hdr(skb);
349 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
350 iph->tot_len = htons(skb->len);
351 if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
352 iph->frag_off = htons(IP_DF);
353 else
354 iph->frag_off = 0;
355 iph->ttl = ip_select_ttl(inet, &rt->u.dst);
356 iph->protocol = sk->sk_protocol;
357 iph->saddr = rt->rt_src;
358 iph->daddr = rt->rt_dst;
359 /* Transport layer set skb->h.foo itself. */
361 if (opt && opt->optlen) {
362 iph->ihl += opt->optlen >> 2;
363 ip_options_build(skb, opt, inet->daddr, rt, 0);
366 ip_select_ident_more(iph, &rt->u.dst, sk,
367 (skb_shinfo(skb)->gso_segs ?: 1) - 1);
369 /* Add an IP checksum. */
370 ip_send_check(iph);
372 skb->priority = sk->sk_priority;
374 return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
375 dst_output);
377 no_route:
378 IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
379 kfree_skb(skb);
380 return -EHOSTUNREACH;
384 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
386 to->pkt_type = from->pkt_type;
387 to->priority = from->priority;
388 to->protocol = from->protocol;
389 dst_release(to->dst);
390 to->dst = dst_clone(from->dst);
391 to->dev = from->dev;
392 to->mark = from->mark;
394 /* Copy the flags to each fragment. */
395 IPCB(to)->flags = IPCB(from)->flags;
397 #ifdef CONFIG_NET_SCHED
398 to->tc_index = from->tc_index;
399 #endif
400 nf_copy(to, from);
401 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
402 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
403 to->nf_trace = from->nf_trace;
404 #endif
405 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
406 to->ipvs_property = from->ipvs_property;
407 #endif
408 skb_copy_secmark(to, from);
412 * This IP datagram is too large to be sent in one piece. Break it up into
413 * smaller pieces (each of size equal to IP header plus
414 * a block of the data of the original IP data part) that will yet fit in a
415 * single device frame, and queue such a frame for sending.
418 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
420 struct iphdr *iph;
421 int raw = 0;
422 int ptr;
423 struct net_device *dev;
424 struct sk_buff *skb2;
425 unsigned int mtu, hlen, left, len, ll_rs, pad;
426 int offset;
427 __be16 not_last_frag;
428 struct rtable *rt = (struct rtable*)skb->dst;
429 int err = 0;
431 dev = rt->u.dst.dev;
434 * Point into the IP datagram header.
437 iph = ip_hdr(skb);
439 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
440 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
441 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
442 htonl(ip_skb_dst_mtu(skb)));
443 kfree_skb(skb);
444 return -EMSGSIZE;
448 * Setup starting values.
451 hlen = iph->ihl * 4;
452 mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */
453 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
455 /* When frag_list is given, use it. First, check its validity:
456 * some transformers could create wrong frag_list or break existing
457 * one, it is not prohibited. In this case fall back to copying.
459 * LATER: this step can be merged to real generation of fragments,
460 * we can switch to copy when see the first bad fragment.
462 if (skb_shinfo(skb)->frag_list) {
463 struct sk_buff *frag;
464 int first_len = skb_pagelen(skb);
466 if (first_len - hlen > mtu ||
467 ((first_len - hlen) & 7) ||
468 (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
469 skb_cloned(skb))
470 goto slow_path;
472 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
473 /* Correct geometry. */
474 if (frag->len > mtu ||
475 ((frag->len & 7) && frag->next) ||
476 skb_headroom(frag) < hlen)
477 goto slow_path;
479 /* Partially cloned skb? */
480 if (skb_shared(frag))
481 goto slow_path;
483 BUG_ON(frag->sk);
484 if (skb->sk) {
485 sock_hold(skb->sk);
486 frag->sk = skb->sk;
487 frag->destructor = sock_wfree;
488 skb->truesize -= frag->truesize;
492 /* Everything is OK. Generate! */
494 err = 0;
495 offset = 0;
496 frag = skb_shinfo(skb)->frag_list;
497 skb_shinfo(skb)->frag_list = NULL;
498 skb->data_len = first_len - skb_headlen(skb);
499 skb->len = first_len;
500 iph->tot_len = htons(first_len);
501 iph->frag_off = htons(IP_MF);
502 ip_send_check(iph);
504 for (;;) {
505 /* Prepare header of the next frame,
506 * before previous one went down. */
507 if (frag) {
508 frag->ip_summed = CHECKSUM_NONE;
509 skb_reset_transport_header(frag);
510 __skb_push(frag, hlen);
511 skb_reset_network_header(frag);
512 memcpy(skb_network_header(frag), iph, hlen);
513 iph = ip_hdr(frag);
514 iph->tot_len = htons(frag->len);
515 ip_copy_metadata(frag, skb);
516 if (offset == 0)
517 ip_options_fragment(frag);
518 offset += skb->len - hlen;
519 iph->frag_off = htons(offset>>3);
520 if (frag->next != NULL)
521 iph->frag_off |= htons(IP_MF);
522 /* Ready, complete checksum */
523 ip_send_check(iph);
526 err = output(skb);
528 if (!err)
529 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
530 if (err || !frag)
531 break;
533 skb = frag;
534 frag = skb->next;
535 skb->next = NULL;
538 if (err == 0) {
539 IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
540 return 0;
543 while (frag) {
544 skb = frag->next;
545 kfree_skb(frag);
546 frag = skb;
548 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
549 return err;
552 slow_path:
553 left = skb->len - hlen; /* Space per frame */
554 ptr = raw + hlen; /* Where to start from */
556 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
557 * we need to make room for the encapsulating header
559 pad = nf_bridge_pad(skb);
560 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, pad);
561 mtu -= pad;
564 * Fragment the datagram.
567 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
568 not_last_frag = iph->frag_off & htons(IP_MF);
571 * Keep copying data until we run out.
574 while (left > 0) {
575 len = left;
576 /* IF: it doesn't fit, use 'mtu' - the data space left */
577 if (len > mtu)
578 len = mtu;
579 /* IF: we are not sending upto and including the packet end
580 then align the next start on an eight byte boundary */
581 if (len < left) {
582 len &= ~7;
585 * Allocate buffer.
588 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
589 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
590 err = -ENOMEM;
591 goto fail;
595 * Set up data on packet
598 ip_copy_metadata(skb2, skb);
599 skb_reserve(skb2, ll_rs);
600 skb_put(skb2, len + hlen);
601 skb_reset_network_header(skb2);
602 skb2->transport_header = skb2->network_header + hlen;
605 * Charge the memory for the fragment to any owner
606 * it might possess
609 if (skb->sk)
610 skb_set_owner_w(skb2, skb->sk);
613 * Copy the packet header into the new buffer.
616 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
619 * Copy a block of the IP datagram.
621 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
622 BUG();
623 left -= len;
626 * Fill in the new header fields.
628 iph = ip_hdr(skb2);
629 iph->frag_off = htons((offset >> 3));
631 /* ANK: dirty, but effective trick. Upgrade options only if
632 * the segment to be fragmented was THE FIRST (otherwise,
633 * options are already fixed) and make it ONCE
634 * on the initial skb, so that all the following fragments
635 * will inherit fixed options.
637 if (offset == 0)
638 ip_options_fragment(skb);
641 * Added AC : If we are fragmenting a fragment that's not the
642 * last fragment then keep MF on each bit
644 if (left > 0 || not_last_frag)
645 iph->frag_off |= htons(IP_MF);
646 ptr += len;
647 offset += len;
650 * Put this fragment into the sending queue.
652 iph->tot_len = htons(len + hlen);
654 ip_send_check(iph);
656 err = output(skb2);
657 if (err)
658 goto fail;
660 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
662 kfree_skb(skb);
663 IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
664 return err;
666 fail:
667 kfree_skb(skb);
668 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
669 return err;
672 EXPORT_SYMBOL(ip_fragment);
675 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
677 struct iovec *iov = from;
679 if (skb->ip_summed == CHECKSUM_PARTIAL) {
680 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
681 return -EFAULT;
682 } else {
683 __wsum csum = 0;
684 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
685 return -EFAULT;
686 skb->csum = csum_block_add(skb->csum, csum, odd);
688 return 0;
691 static inline __wsum
692 csum_page(struct page *page, int offset, int copy)
694 char *kaddr;
695 __wsum csum;
696 kaddr = kmap(page);
697 csum = csum_partial(kaddr + offset, copy, 0);
698 kunmap(page);
699 return csum;
702 static inline int ip_ufo_append_data(struct sock *sk,
703 int getfrag(void *from, char *to, int offset, int len,
704 int odd, struct sk_buff *skb),
705 void *from, int length, int hh_len, int fragheaderlen,
706 int transhdrlen, int mtu,unsigned int flags)
708 struct sk_buff *skb;
709 int err;
711 /* There is support for UDP fragmentation offload by network
712 * device, so create one single skb packet containing complete
713 * udp datagram
715 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
716 skb = sock_alloc_send_skb(sk,
717 hh_len + fragheaderlen + transhdrlen + 20,
718 (flags & MSG_DONTWAIT), &err);
720 if (skb == NULL)
721 return err;
723 /* reserve space for Hardware header */
724 skb_reserve(skb, hh_len);
726 /* create space for UDP/IP header */
727 skb_put(skb,fragheaderlen + transhdrlen);
729 /* initialize network header pointer */
730 skb_reset_network_header(skb);
732 /* initialize protocol header pointer */
733 skb->transport_header = skb->network_header + fragheaderlen;
735 skb->ip_summed = CHECKSUM_PARTIAL;
736 skb->csum = 0;
737 sk->sk_sndmsg_off = 0;
740 err = skb_append_datato_frags(sk,skb, getfrag, from,
741 (length - transhdrlen));
742 if (!err) {
743 /* specify the length of each IP datagram fragment*/
744 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
745 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
746 __skb_queue_tail(&sk->sk_write_queue, skb);
748 return 0;
750 /* There is not enough support do UFO ,
751 * so follow normal path
753 kfree_skb(skb);
754 return err;
758 * ip_append_data() and ip_append_page() can make one large IP datagram
759 * from many pieces of data. Each pieces will be holded on the socket
760 * until ip_push_pending_frames() is called. Each piece can be a page
761 * or non-page data.
763 * Not only UDP, other transport protocols - e.g. raw sockets - can use
764 * this interface potentially.
766 * LATER: length must be adjusted by pad at tail, when it is required.
768 int ip_append_data(struct sock *sk,
769 int getfrag(void *from, char *to, int offset, int len,
770 int odd, struct sk_buff *skb),
771 void *from, int length, int transhdrlen,
772 struct ipcm_cookie *ipc, struct rtable *rt,
773 unsigned int flags)
775 struct inet_sock *inet = inet_sk(sk);
776 struct sk_buff *skb;
778 struct ip_options *opt = NULL;
779 int hh_len;
780 int exthdrlen;
781 int mtu;
782 int copy;
783 int err;
784 int offset = 0;
785 unsigned int maxfraglen, fragheaderlen;
786 int csummode = CHECKSUM_NONE;
788 if (flags&MSG_PROBE)
789 return 0;
791 if (skb_queue_empty(&sk->sk_write_queue)) {
793 * setup for corking.
795 opt = ipc->opt;
796 if (opt) {
797 if (inet->cork.opt == NULL) {
798 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
799 if (unlikely(inet->cork.opt == NULL))
800 return -ENOBUFS;
802 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
803 inet->cork.flags |= IPCORK_OPT;
804 inet->cork.addr = ipc->addr;
806 dst_hold(&rt->u.dst);
807 inet->cork.fragsize = mtu = inet->pmtudisc == IP_PMTUDISC_PROBE ?
808 rt->u.dst.dev->mtu :
809 dst_mtu(rt->u.dst.path);
810 inet->cork.rt = rt;
811 inet->cork.length = 0;
812 sk->sk_sndmsg_page = NULL;
813 sk->sk_sndmsg_off = 0;
814 if ((exthdrlen = rt->u.dst.header_len) != 0) {
815 length += exthdrlen;
816 transhdrlen += exthdrlen;
818 } else {
819 rt = inet->cork.rt;
820 if (inet->cork.flags & IPCORK_OPT)
821 opt = inet->cork.opt;
823 transhdrlen = 0;
824 exthdrlen = 0;
825 mtu = inet->cork.fragsize;
827 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
829 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
830 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
832 if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
833 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen);
834 return -EMSGSIZE;
838 * transhdrlen > 0 means that this is the first fragment and we wish
839 * it won't be fragmented in the future.
841 if (transhdrlen &&
842 length + fragheaderlen <= mtu &&
843 rt->u.dst.dev->features & NETIF_F_V4_CSUM &&
844 !exthdrlen)
845 csummode = CHECKSUM_PARTIAL;
847 inet->cork.length += length;
848 if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
849 (rt->u.dst.dev->features & NETIF_F_UFO)) {
851 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,
852 fragheaderlen, transhdrlen, mtu,
853 flags);
854 if (err)
855 goto error;
856 return 0;
859 /* So, what's going on in the loop below?
861 * We use calculated fragment length to generate chained skb,
862 * each of segments is IP fragment ready for sending to network after
863 * adding appropriate IP header.
866 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
867 goto alloc_new_skb;
869 while (length > 0) {
870 /* Check if the remaining data fits into current packet. */
871 copy = mtu - skb->len;
872 if (copy < length)
873 copy = maxfraglen - skb->len;
874 if (copy <= 0) {
875 char *data;
876 unsigned int datalen;
877 unsigned int fraglen;
878 unsigned int fraggap;
879 unsigned int alloclen;
880 struct sk_buff *skb_prev;
881 alloc_new_skb:
882 skb_prev = skb;
883 if (skb_prev)
884 fraggap = skb_prev->len - maxfraglen;
885 else
886 fraggap = 0;
889 * If remaining data exceeds the mtu,
890 * we know we need more fragment(s).
892 datalen = length + fraggap;
893 if (datalen > mtu - fragheaderlen)
894 datalen = maxfraglen - fragheaderlen;
895 fraglen = datalen + fragheaderlen;
897 if ((flags & MSG_MORE) &&
898 !(rt->u.dst.dev->features&NETIF_F_SG))
899 alloclen = mtu;
900 else
901 alloclen = datalen + fragheaderlen;
903 /* The last fragment gets additional space at tail.
904 * Note, with MSG_MORE we overallocate on fragments,
905 * because we have no idea what fragment will be
906 * the last.
908 if (datalen == length + fraggap)
909 alloclen += rt->u.dst.trailer_len;
911 if (transhdrlen) {
912 skb = sock_alloc_send_skb(sk,
913 alloclen + hh_len + 15,
914 (flags & MSG_DONTWAIT), &err);
915 } else {
916 skb = NULL;
917 if (atomic_read(&sk->sk_wmem_alloc) <=
918 2 * sk->sk_sndbuf)
919 skb = sock_wmalloc(sk,
920 alloclen + hh_len + 15, 1,
921 sk->sk_allocation);
922 if (unlikely(skb == NULL))
923 err = -ENOBUFS;
925 if (skb == NULL)
926 goto error;
929 * Fill in the control structures
931 skb->ip_summed = csummode;
932 skb->csum = 0;
933 skb_reserve(skb, hh_len);
936 * Find where to start putting bytes.
938 data = skb_put(skb, fraglen);
939 skb_set_network_header(skb, exthdrlen);
940 skb->transport_header = (skb->network_header +
941 fragheaderlen);
942 data += fragheaderlen;
944 if (fraggap) {
945 skb->csum = skb_copy_and_csum_bits(
946 skb_prev, maxfraglen,
947 data + transhdrlen, fraggap, 0);
948 skb_prev->csum = csum_sub(skb_prev->csum,
949 skb->csum);
950 data += fraggap;
951 pskb_trim_unique(skb_prev, maxfraglen);
954 copy = datalen - transhdrlen - fraggap;
955 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
956 err = -EFAULT;
957 kfree_skb(skb);
958 goto error;
961 offset += copy;
962 length -= datalen - fraggap;
963 transhdrlen = 0;
964 exthdrlen = 0;
965 csummode = CHECKSUM_NONE;
968 * Put the packet on the pending queue.
970 __skb_queue_tail(&sk->sk_write_queue, skb);
971 continue;
974 if (copy > length)
975 copy = length;
977 if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
978 unsigned int off;
980 off = skb->len;
981 if (getfrag(from, skb_put(skb, copy),
982 offset, copy, off, skb) < 0) {
983 __skb_trim(skb, off);
984 err = -EFAULT;
985 goto error;
987 } else {
988 int i = skb_shinfo(skb)->nr_frags;
989 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
990 struct page *page = sk->sk_sndmsg_page;
991 int off = sk->sk_sndmsg_off;
992 unsigned int left;
994 if (page && (left = PAGE_SIZE - off) > 0) {
995 if (copy >= left)
996 copy = left;
997 if (page != frag->page) {
998 if (i == MAX_SKB_FRAGS) {
999 err = -EMSGSIZE;
1000 goto error;
1002 get_page(page);
1003 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1004 frag = &skb_shinfo(skb)->frags[i];
1006 } else if (i < MAX_SKB_FRAGS) {
1007 if (copy > PAGE_SIZE)
1008 copy = PAGE_SIZE;
1009 page = alloc_pages(sk->sk_allocation, 0);
1010 if (page == NULL) {
1011 err = -ENOMEM;
1012 goto error;
1014 sk->sk_sndmsg_page = page;
1015 sk->sk_sndmsg_off = 0;
1017 skb_fill_page_desc(skb, i, page, 0, 0);
1018 frag = &skb_shinfo(skb)->frags[i];
1019 } else {
1020 err = -EMSGSIZE;
1021 goto error;
1023 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1024 err = -EFAULT;
1025 goto error;
1027 sk->sk_sndmsg_off += copy;
1028 frag->size += copy;
1029 skb->len += copy;
1030 skb->data_len += copy;
1031 skb->truesize += copy;
1032 atomic_add(copy, &sk->sk_wmem_alloc);
1034 offset += copy;
1035 length -= copy;
1038 return 0;
1040 error:
1041 inet->cork.length -= length;
1042 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1043 return err;
1046 ssize_t ip_append_page(struct sock *sk, struct page *page,
1047 int offset, size_t size, int flags)
1049 struct inet_sock *inet = inet_sk(sk);
1050 struct sk_buff *skb;
1051 struct rtable *rt;
1052 struct ip_options *opt = NULL;
1053 int hh_len;
1054 int mtu;
1055 int len;
1056 int err;
1057 unsigned int maxfraglen, fragheaderlen, fraggap;
1059 if (inet->hdrincl)
1060 return -EPERM;
1062 if (flags&MSG_PROBE)
1063 return 0;
1065 if (skb_queue_empty(&sk->sk_write_queue))
1066 return -EINVAL;
1068 rt = inet->cork.rt;
1069 if (inet->cork.flags & IPCORK_OPT)
1070 opt = inet->cork.opt;
1072 if (!(rt->u.dst.dev->features&NETIF_F_SG))
1073 return -EOPNOTSUPP;
1075 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1076 mtu = inet->cork.fragsize;
1078 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1079 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1081 if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1082 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
1083 return -EMSGSIZE;
1086 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1087 return -EINVAL;
1089 inet->cork.length += size;
1090 if ((sk->sk_protocol == IPPROTO_UDP) &&
1091 (rt->u.dst.dev->features & NETIF_F_UFO)) {
1092 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1093 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1097 while (size > 0) {
1098 int i;
1100 if (skb_is_gso(skb))
1101 len = size;
1102 else {
1104 /* Check if the remaining data fits into current packet. */
1105 len = mtu - skb->len;
1106 if (len < size)
1107 len = maxfraglen - skb->len;
1109 if (len <= 0) {
1110 struct sk_buff *skb_prev;
1111 int alloclen;
1113 skb_prev = skb;
1114 fraggap = skb_prev->len - maxfraglen;
1116 alloclen = fragheaderlen + hh_len + fraggap + 15;
1117 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1118 if (unlikely(!skb)) {
1119 err = -ENOBUFS;
1120 goto error;
1124 * Fill in the control structures
1126 skb->ip_summed = CHECKSUM_NONE;
1127 skb->csum = 0;
1128 skb_reserve(skb, hh_len);
1131 * Find where to start putting bytes.
1133 skb_put(skb, fragheaderlen + fraggap);
1134 skb_reset_network_header(skb);
1135 skb->transport_header = (skb->network_header +
1136 fragheaderlen);
1137 if (fraggap) {
1138 skb->csum = skb_copy_and_csum_bits(skb_prev,
1139 maxfraglen,
1140 skb_transport_header(skb),
1141 fraggap, 0);
1142 skb_prev->csum = csum_sub(skb_prev->csum,
1143 skb->csum);
1144 pskb_trim_unique(skb_prev, maxfraglen);
1148 * Put the packet on the pending queue.
1150 __skb_queue_tail(&sk->sk_write_queue, skb);
1151 continue;
1154 i = skb_shinfo(skb)->nr_frags;
1155 if (len > size)
1156 len = size;
1157 if (skb_can_coalesce(skb, i, page, offset)) {
1158 skb_shinfo(skb)->frags[i-1].size += len;
1159 } else if (i < MAX_SKB_FRAGS) {
1160 get_page(page);
1161 skb_fill_page_desc(skb, i, page, offset, len);
1162 } else {
1163 err = -EMSGSIZE;
1164 goto error;
1167 if (skb->ip_summed == CHECKSUM_NONE) {
1168 __wsum csum;
1169 csum = csum_page(page, offset, len);
1170 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1173 skb->len += len;
1174 skb->data_len += len;
1175 skb->truesize += len;
1176 atomic_add(len, &sk->sk_wmem_alloc);
1177 offset += len;
1178 size -= len;
1180 return 0;
1182 error:
1183 inet->cork.length -= size;
1184 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1185 return err;
1188 static void ip_cork_release(struct inet_sock *inet)
1190 inet->cork.flags &= ~IPCORK_OPT;
1191 kfree(inet->cork.opt);
1192 inet->cork.opt = NULL;
1193 if (inet->cork.rt) {
1194 ip_rt_put(inet->cork.rt);
1195 inet->cork.rt = NULL;
1200 * Combined all pending IP fragments on the socket as one IP datagram
1201 * and push them out.
1203 int ip_push_pending_frames(struct sock *sk)
1205 struct sk_buff *skb, *tmp_skb;
1206 struct sk_buff **tail_skb;
1207 struct inet_sock *inet = inet_sk(sk);
1208 struct ip_options *opt = NULL;
1209 struct rtable *rt = inet->cork.rt;
1210 struct iphdr *iph;
1211 __be16 df = 0;
1212 __u8 ttl;
1213 int err = 0;
1215 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1216 goto out;
1217 tail_skb = &(skb_shinfo(skb)->frag_list);
1219 /* move skb->data to ip header from ext header */
1220 if (skb->data < skb_network_header(skb))
1221 __skb_pull(skb, skb_network_offset(skb));
1222 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1223 __skb_pull(tmp_skb, skb_network_header_len(skb));
1224 *tail_skb = tmp_skb;
1225 tail_skb = &(tmp_skb->next);
1226 skb->len += tmp_skb->len;
1227 skb->data_len += tmp_skb->len;
1228 skb->truesize += tmp_skb->truesize;
1229 __sock_put(tmp_skb->sk);
1230 tmp_skb->destructor = NULL;
1231 tmp_skb->sk = NULL;
1234 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1235 * to fragment the frame generated here. No matter, what transforms
1236 * how transforms change size of the packet, it will come out.
1238 if (inet->pmtudisc < IP_PMTUDISC_DO)
1239 skb->local_df = 1;
1241 /* DF bit is set when we want to see DF on outgoing frames.
1242 * If local_df is set too, we still allow to fragment this frame
1243 * locally. */
1244 if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1245 (skb->len <= dst_mtu(&rt->u.dst) &&
1246 ip_dont_fragment(sk, &rt->u.dst)))
1247 df = htons(IP_DF);
1249 if (inet->cork.flags & IPCORK_OPT)
1250 opt = inet->cork.opt;
1252 if (rt->rt_type == RTN_MULTICAST)
1253 ttl = inet->mc_ttl;
1254 else
1255 ttl = ip_select_ttl(inet, &rt->u.dst);
1257 iph = (struct iphdr *)skb->data;
1258 iph->version = 4;
1259 iph->ihl = 5;
1260 if (opt) {
1261 iph->ihl += opt->optlen>>2;
1262 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1264 iph->tos = inet->tos;
1265 iph->tot_len = htons(skb->len);
1266 iph->frag_off = df;
1267 ip_select_ident(iph, &rt->u.dst, sk);
1268 iph->ttl = ttl;
1269 iph->protocol = sk->sk_protocol;
1270 iph->saddr = rt->rt_src;
1271 iph->daddr = rt->rt_dst;
1272 ip_send_check(iph);
1274 skb->priority = sk->sk_priority;
1275 skb->dst = dst_clone(&rt->u.dst);
1277 if (iph->protocol == IPPROTO_ICMP)
1278 icmp_out_count(((struct icmphdr *)
1279 skb_transport_header(skb))->type);
1281 /* Netfilter gets whole the not fragmented skb. */
1282 err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
1283 skb->dst->dev, dst_output);
1284 if (err) {
1285 if (err > 0)
1286 err = inet->recverr ? net_xmit_errno(err) : 0;
1287 if (err)
1288 goto error;
1291 out:
1292 ip_cork_release(inet);
1293 return err;
1295 error:
1296 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1297 goto out;
1301 * Throw away all pending data on the socket.
1303 void ip_flush_pending_frames(struct sock *sk)
1305 struct sk_buff *skb;
1307 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
1308 kfree_skb(skb);
1310 ip_cork_release(inet_sk(sk));
1315 * Fetch data from kernel space and fill in checksum if needed.
1317 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1318 int len, int odd, struct sk_buff *skb)
1320 __wsum csum;
1322 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1323 skb->csum = csum_block_add(skb->csum, csum, odd);
1324 return 0;
1328 * Generic function to send a packet as reply to another packet.
1329 * Used to send TCP resets so far. ICMP should use this function too.
1331 * Should run single threaded per socket because it uses the sock
1332 * structure to pass arguments.
1334 * LATER: switch from ip_build_xmit to ip_append_*
1336 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
1337 unsigned int len)
1339 struct inet_sock *inet = inet_sk(sk);
1340 struct {
1341 struct ip_options opt;
1342 char data[40];
1343 } replyopts;
1344 struct ipcm_cookie ipc;
1345 __be32 daddr;
1346 struct rtable *rt = (struct rtable*)skb->dst;
1348 if (ip_options_echo(&replyopts.opt, skb))
1349 return;
1351 daddr = ipc.addr = rt->rt_src;
1352 ipc.opt = NULL;
1354 if (replyopts.opt.optlen) {
1355 ipc.opt = &replyopts.opt;
1357 if (ipc.opt->srr)
1358 daddr = replyopts.opt.faddr;
1362 struct flowi fl = { .oif = arg->bound_dev_if,
1363 .nl_u = { .ip4_u =
1364 { .daddr = daddr,
1365 .saddr = rt->rt_spec_dst,
1366 .tos = RT_TOS(ip_hdr(skb)->tos) } },
1367 /* Not quite clean, but right. */
1368 .uli_u = { .ports =
1369 { .sport = tcp_hdr(skb)->dest,
1370 .dport = tcp_hdr(skb)->source } },
1371 .proto = sk->sk_protocol };
1372 security_skb_classify_flow(skb, &fl);
1373 if (ip_route_output_key(&rt, &fl))
1374 return;
1377 /* And let IP do all the hard work.
1379 This chunk is not reenterable, hence spinlock.
1380 Note that it uses the fact, that this function is called
1381 with locally disabled BH and that sk cannot be already spinlocked.
1383 bh_lock_sock(sk);
1384 inet->tos = ip_hdr(skb)->tos;
1385 sk->sk_priority = skb->priority;
1386 sk->sk_protocol = ip_hdr(skb)->protocol;
1387 sk->sk_bound_dev_if = arg->bound_dev_if;
1388 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1389 &ipc, rt, MSG_DONTWAIT);
1390 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1391 if (arg->csumoffset >= 0)
1392 *((__sum16 *)skb_transport_header(skb) +
1393 arg->csumoffset) = csum_fold(csum_add(skb->csum,
1394 arg->csum));
1395 skb->ip_summed = CHECKSUM_NONE;
1396 ip_push_pending_frames(sk);
1399 bh_unlock_sock(sk);
1401 ip_rt_put(rt);
1404 void __init ip_init(void)
1406 ip_rt_init();
1407 inet_initpeers();
1409 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1410 igmp_mc_proc_init();
1411 #endif
1414 EXPORT_SYMBOL(ip_generic_getfrag);
1415 EXPORT_SYMBOL(ip_queue_xmit);
1416 EXPORT_SYMBOL(ip_send_check);