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.
9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
11 * Alan Cox, <Alan.Cox@linux.org>
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>
18 * See ip_input.c for original log
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
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
42 * Hirokazu Takahashi: sendfile() on UDP works now.
45 #include <linux/uaccess.h>
46 #include <linux/module.h>
47 #include <linux/types.h>
48 #include <linux/kernel.h>
50 #include <linux/string.h>
51 #include <linux/errno.h>
52 #include <linux/highmem.h>
53 #include <linux/slab.h>
55 #include <linux/socket.h>
56 #include <linux/sockios.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>
67 #include <net/protocol.h>
68 #include <net/route.h>
70 #include <linux/skbuff.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>
85 ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
87 int (*output)(struct net *, struct sock *, struct sk_buff *));
89 /* Generate a checksum for an outgoing IP datagram. */
90 void ip_send_check(struct iphdr *iph)
93 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
95 EXPORT_SYMBOL(ip_send_check);
97 int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
99 struct iphdr *iph = ip_hdr(skb);
101 iph->tot_len = htons(skb->len);
104 /* if egress device is enslaved to an L3 master device pass the
105 * skb to its handler for processing
107 skb = l3mdev_ip_out(sk, skb);
111 skb->protocol = htons(ETH_P_IP);
113 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
114 net, sk, skb, NULL, skb_dst(skb)->dev,
118 int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
122 err = __ip_local_out(net, sk, skb);
123 if (likely(err == 1))
124 err = dst_output(net, sk, skb);
128 EXPORT_SYMBOL_GPL(ip_local_out);
130 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
132 int ttl = inet->uc_ttl;
135 ttl = ip4_dst_hoplimit(dst);
140 * Add an ip header to a skbuff and send it out.
143 int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
144 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
146 struct inet_sock *inet = inet_sk(sk);
147 struct rtable *rt = skb_rtable(skb);
148 struct net *net = sock_net(sk);
151 /* Build the IP header. */
152 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
153 skb_reset_network_header(skb);
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);
161 iph->protocol = sk->sk_protocol;
162 if (ip_dont_fragment(sk, &rt->dst)) {
163 iph->frag_off = htons(IP_DF);
167 __ip_select_ident(net, iph, 1);
170 if (opt && opt->opt.optlen) {
171 iph->ihl += opt->opt.optlen>>2;
172 ip_options_build(skb, &opt->opt, daddr, rt, 0);
175 skb->priority = sk->sk_priority;
177 skb->mark = sk->sk_mark;
180 return ip_local_out(net, skb->sk, skb);
182 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
184 static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
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;
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);
198 /* Be paranoid, rather than too clever. */
199 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
200 struct sk_buff *skb2;
202 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
208 skb_set_owner_w(skb2, skb->sk);
213 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
214 int res = lwtunnel_xmit(skb);
216 if (res < 0 || res == LWTUNNEL_XMIT_DONE)
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)) {
228 sock_confirm_neigh(skb, neigh);
229 res = neigh_output(neigh, skb);
231 rcu_read_unlock_bh();
234 rcu_read_unlock_bh();
236 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
242 static int ip_finish_output_gso(struct net *net, struct sock *sk,
243 struct sk_buff *skb, unsigned int mtu)
245 netdev_features_t features;
246 struct sk_buff *segs;
249 /* common case: seglen is <= mtu
251 if (skb_gso_validate_mtu(skb, mtu))
252 return ip_finish_output2(net, sk, skb);
254 /* Slowpath - GSO segment length exceeds the egress MTU.
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
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
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)) {
278 struct sk_buff *nskb = segs->next;
282 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
292 static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
297 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
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);
310 mtu = ip_skb_dst_mtu(sk, skb);
312 return ip_finish_output_gso(net, sk, skb, mtu);
314 if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
315 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
317 return ip_finish_output2(net, sk, skb);
320 static int ip_mc_finish_output(struct net *net, struct sock *sk,
325 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
331 return dev_loopback_xmit(net, sk, skb);
334 int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
336 struct rtable *rt = skb_rtable(skb);
337 struct net_device *dev = rt->dst.dev;
340 * If the indicated interface is up and running, send the packet.
342 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
345 skb->protocol = htons(ETH_P_IP);
348 * Multicasts are looped back for other local users
351 if (rt->rt_flags&RTCF_MULTICAST) {
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
360 This check is duplicated in ip_mr_input at the moment.
363 ((rt->rt_flags & RTCF_LOCAL) ||
364 !(IPCB(skb)->flags & IPSKB_FORWARDED))
367 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
369 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
370 net, sk, newskb, NULL, newskb->dev,
371 ip_mc_finish_output);
374 /* Multicasts with ttl 0 must not go beyond the host */
376 if (ip_hdr(skb)->ttl == 0) {
382 if (rt->rt_flags&RTCF_BROADCAST) {
383 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
385 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
386 net, sk, newskb, NULL, newskb->dev,
387 ip_mc_finish_output);
390 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
391 net, sk, skb, NULL, skb->dev,
393 !(IPCB(skb)->flags & IPSKB_REROUTED));
396 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
398 struct net_device *dev = skb_dst(skb)->dev;
400 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
403 skb->protocol = htons(ETH_P_IP);
405 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
406 net, sk, skb, NULL, dev,
408 !(IPCB(skb)->flags & IPSKB_REROUTED));
412 * copy saddr and daddr, possibly using 64bit load/stores
414 * iph->saddr = fl4->saddr;
415 * iph->daddr = fl4->daddr;
417 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
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));
425 /* Note: skb->sk can be different from sk, in case of tunnels */
426 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
428 struct inet_sock *inet = inet_sk(sk);
429 struct net *net = sock_net(sk);
430 struct ip_options_rcu *inet_opt;
436 /* Skip all of this if the packet is already routed,
437 * f.e. by something like SCTP.
440 inet_opt = rcu_dereference(inet->inet_opt);
442 rt = skb_rtable(skb);
446 /* Make sure we can route this packet. */
447 rt = (struct rtable *)__sk_dst_check(sk, 0);
451 /* Use correct destination address if we have options. */
452 daddr = inet->inet_daddr;
453 if (inet_opt && inet_opt->opt.srr)
454 daddr = inet_opt->opt.faddr;
456 /* If this fails, retransmit mechanism of transport layer will
457 * keep trying until route appears or the connection times
460 rt = ip_route_output_ports(net, fl4, sk,
461 daddr, inet->inet_saddr,
466 sk->sk_bound_dev_if);
469 sk_setup_caps(sk, &rt->dst);
471 skb_dst_set_noref(skb, &rt->dst);
474 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
477 /* OK, we know where to send it, allocate and build IP header. */
478 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
479 skb_reset_network_header(skb);
481 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
482 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
483 iph->frag_off = htons(IP_DF);
486 iph->ttl = ip_select_ttl(inet, &rt->dst);
487 iph->protocol = sk->sk_protocol;
488 ip_copy_addrs(iph, fl4);
490 /* Transport layer set skb->h.foo itself. */
492 if (inet_opt && inet_opt->opt.optlen) {
493 iph->ihl += inet_opt->opt.optlen >> 2;
494 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
497 ip_select_ident_segs(net, skb, sk,
498 skb_shinfo(skb)->gso_segs ?: 1);
500 /* TODO : should we use skb->sk here instead of sk ? */
501 skb->priority = sk->sk_priority;
502 skb->mark = sk->sk_mark;
504 res = ip_local_out(net, sk, skb);
510 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
512 return -EHOSTUNREACH;
514 EXPORT_SYMBOL(ip_queue_xmit);
516 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
518 to->pkt_type = from->pkt_type;
519 to->priority = from->priority;
520 to->protocol = from->protocol;
522 skb_dst_copy(to, from);
524 to->mark = from->mark;
526 skb_copy_hash(to, from);
528 /* Copy the flags to each fragment. */
529 IPCB(to)->flags = IPCB(from)->flags;
531 #ifdef CONFIG_NET_SCHED
532 to->tc_index = from->tc_index;
535 #if IS_ENABLED(CONFIG_IP_VS)
536 to->ipvs_property = from->ipvs_property;
538 skb_copy_secmark(to, from);
541 static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
543 int (*output)(struct net *, struct sock *, struct sk_buff *))
545 struct iphdr *iph = ip_hdr(skb);
547 if ((iph->frag_off & htons(IP_DF)) == 0)
548 return ip_do_fragment(net, sk, skb, output);
550 if (unlikely(!skb->ignore_df ||
551 (IPCB(skb)->frag_max_size &&
552 IPCB(skb)->frag_max_size > mtu))) {
553 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
554 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
560 return ip_do_fragment(net, sk, skb, output);
564 * This IP datagram is too large to be sent in one piece. Break it up into
565 * smaller pieces (each of size equal to IP header plus
566 * a block of the data of the original IP data part) that will yet fit in a
567 * single device frame, and queue such a frame for sending.
570 int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
571 int (*output)(struct net *, struct sock *, struct sk_buff *))
575 struct sk_buff *skb2;
576 unsigned int mtu, hlen, left, len, ll_rs;
578 __be16 not_last_frag;
579 struct rtable *rt = skb_rtable(skb);
582 /* for offloaded checksums cleanup checksum before fragmentation */
583 if (skb->ip_summed == CHECKSUM_PARTIAL &&
584 (err = skb_checksum_help(skb)))
588 * Point into the IP datagram header.
593 mtu = ip_skb_dst_mtu(sk, skb);
594 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
595 mtu = IPCB(skb)->frag_max_size;
598 * Setup starting values.
602 mtu = mtu - hlen; /* Size of data space */
603 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
604 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
606 /* When frag_list is given, use it. First, check its validity:
607 * some transformers could create wrong frag_list or break existing
608 * one, it is not prohibited. In this case fall back to copying.
610 * LATER: this step can be merged to real generation of fragments,
611 * we can switch to copy when see the first bad fragment.
613 if (skb_has_frag_list(skb)) {
614 struct sk_buff *frag, *frag2;
615 unsigned int first_len = skb_pagelen(skb);
617 if (first_len - hlen > mtu ||
618 ((first_len - hlen) & 7) ||
619 ip_is_fragment(iph) ||
621 skb_headroom(skb) < ll_rs)
624 skb_walk_frags(skb, frag) {
625 /* Correct geometry. */
626 if (frag->len > mtu ||
627 ((frag->len & 7) && frag->next) ||
628 skb_headroom(frag) < hlen + ll_rs)
629 goto slow_path_clean;
631 /* Partially cloned skb? */
632 if (skb_shared(frag))
633 goto slow_path_clean;
638 frag->destructor = sock_wfree;
640 skb->truesize -= frag->truesize;
643 /* Everything is OK. Generate! */
647 frag = skb_shinfo(skb)->frag_list;
648 skb_frag_list_init(skb);
649 skb->data_len = first_len - skb_headlen(skb);
650 skb->len = first_len;
651 iph->tot_len = htons(first_len);
652 iph->frag_off = htons(IP_MF);
656 /* Prepare header of the next frame,
657 * before previous one went down. */
659 frag->ip_summed = CHECKSUM_NONE;
660 skb_reset_transport_header(frag);
661 __skb_push(frag, hlen);
662 skb_reset_network_header(frag);
663 memcpy(skb_network_header(frag), iph, hlen);
665 iph->tot_len = htons(frag->len);
666 ip_copy_metadata(frag, skb);
668 ip_options_fragment(frag);
669 offset += skb->len - hlen;
670 iph->frag_off = htons(offset>>3);
672 iph->frag_off |= htons(IP_MF);
673 /* Ready, complete checksum */
677 err = output(net, sk, skb);
680 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
690 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
699 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
703 skb_walk_frags(skb, frag2) {
707 frag2->destructor = NULL;
708 skb->truesize += frag2->truesize;
715 left = skb->len - hlen; /* Space per frame */
716 ptr = hlen; /* Where to start from */
719 * Fragment the datagram.
722 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
723 not_last_frag = iph->frag_off & htons(IP_MF);
726 * Keep copying data until we run out.
731 /* IF: it doesn't fit, use 'mtu' - the data space left */
734 /* IF: we are not sending up to and including the packet end
735 then align the next start on an eight byte boundary */
740 /* Allocate buffer */
741 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
748 * Set up data on packet
751 ip_copy_metadata(skb2, skb);
752 skb_reserve(skb2, ll_rs);
753 skb_put(skb2, len + hlen);
754 skb_reset_network_header(skb2);
755 skb2->transport_header = skb2->network_header + hlen;
758 * Charge the memory for the fragment to any owner
763 skb_set_owner_w(skb2, skb->sk);
766 * Copy the packet header into the new buffer.
769 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
772 * Copy a block of the IP datagram.
774 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
779 * Fill in the new header fields.
782 iph->frag_off = htons((offset >> 3));
784 if (IPCB(skb)->flags & IPSKB_FRAG_PMTU)
785 iph->frag_off |= htons(IP_DF);
787 /* ANK: dirty, but effective trick. Upgrade options only if
788 * the segment to be fragmented was THE FIRST (otherwise,
789 * options are already fixed) and make it ONCE
790 * on the initial skb, so that all the following fragments
791 * will inherit fixed options.
794 ip_options_fragment(skb);
797 * Added AC : If we are fragmenting a fragment that's not the
798 * last fragment then keep MF on each bit
800 if (left > 0 || not_last_frag)
801 iph->frag_off |= htons(IP_MF);
806 * Put this fragment into the sending queue.
808 iph->tot_len = htons(len + hlen);
812 err = output(net, sk, skb2);
816 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
819 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
824 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
827 EXPORT_SYMBOL(ip_do_fragment);
830 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
832 struct msghdr *msg = from;
834 if (skb->ip_summed == CHECKSUM_PARTIAL) {
835 if (!copy_from_iter_full(to, len, &msg->msg_iter))
839 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
841 skb->csum = csum_block_add(skb->csum, csum, odd);
845 EXPORT_SYMBOL(ip_generic_getfrag);
848 csum_page(struct page *page, int offset, int copy)
853 csum = csum_partial(kaddr + offset, copy, 0);
858 static int __ip_append_data(struct sock *sk,
860 struct sk_buff_head *queue,
861 struct inet_cork *cork,
862 struct page_frag *pfrag,
863 int getfrag(void *from, char *to, int offset,
864 int len, int odd, struct sk_buff *skb),
865 void *from, int length, int transhdrlen,
868 struct inet_sock *inet = inet_sk(sk);
871 struct ip_options *opt = cork->opt;
878 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
879 int csummode = CHECKSUM_NONE;
880 struct rtable *rt = (struct rtable *)cork->dst;
883 skb = skb_peek_tail(queue);
885 exthdrlen = !skb ? rt->dst.header_len : 0;
886 mtu = cork->fragsize;
887 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
888 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
889 tskey = sk->sk_tskey++;
891 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
893 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
894 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
895 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
897 if (cork->length + length > maxnonfragsize - fragheaderlen) {
898 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
899 mtu - (opt ? opt->optlen : 0));
904 * transhdrlen > 0 means that this is the first fragment and we wish
905 * it won't be fragmented in the future.
908 length + fragheaderlen <= mtu &&
909 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
910 !(flags & MSG_MORE) &&
912 csummode = CHECKSUM_PARTIAL;
914 cork->length += length;
916 /* So, what's going on in the loop below?
918 * We use calculated fragment length to generate chained skb,
919 * each of segments is IP fragment ready for sending to network after
920 * adding appropriate IP header.
927 /* Check if the remaining data fits into current packet. */
928 copy = mtu - skb->len;
930 copy = maxfraglen - skb->len;
933 unsigned int datalen;
934 unsigned int fraglen;
935 unsigned int fraggap;
936 unsigned int alloclen;
937 struct sk_buff *skb_prev;
941 fraggap = skb_prev->len - maxfraglen;
946 * If remaining data exceeds the mtu,
947 * we know we need more fragment(s).
949 datalen = length + fraggap;
950 if (datalen > mtu - fragheaderlen)
951 datalen = maxfraglen - fragheaderlen;
952 fraglen = datalen + fragheaderlen;
954 if ((flags & MSG_MORE) &&
955 !(rt->dst.dev->features&NETIF_F_SG))
960 alloclen += exthdrlen;
962 /* The last fragment gets additional space at tail.
963 * Note, with MSG_MORE we overallocate on fragments,
964 * because we have no idea what fragment will be
967 if (datalen == length + fraggap)
968 alloclen += rt->dst.trailer_len;
971 skb = sock_alloc_send_skb(sk,
972 alloclen + hh_len + 15,
973 (flags & MSG_DONTWAIT), &err);
976 if (refcount_read(&sk->sk_wmem_alloc) <=
978 skb = sock_wmalloc(sk,
979 alloclen + hh_len + 15, 1,
988 * Fill in the control structures
990 skb->ip_summed = csummode;
992 skb_reserve(skb, hh_len);
994 /* only the initial fragment is time stamped */
995 skb_shinfo(skb)->tx_flags = cork->tx_flags;
997 skb_shinfo(skb)->tskey = tskey;
1001 * Find where to start putting bytes.
1003 data = skb_put(skb, fraglen + exthdrlen);
1004 skb_set_network_header(skb, exthdrlen);
1005 skb->transport_header = (skb->network_header +
1007 data += fragheaderlen + exthdrlen;
1010 skb->csum = skb_copy_and_csum_bits(
1011 skb_prev, maxfraglen,
1012 data + transhdrlen, fraggap, 0);
1013 skb_prev->csum = csum_sub(skb_prev->csum,
1016 pskb_trim_unique(skb_prev, maxfraglen);
1019 copy = datalen - transhdrlen - fraggap;
1020 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1027 length -= datalen - fraggap;
1030 csummode = CHECKSUM_NONE;
1032 if ((flags & MSG_CONFIRM) && !skb_prev)
1033 skb_set_dst_pending_confirm(skb, 1);
1036 * Put the packet on the pending queue.
1038 __skb_queue_tail(queue, skb);
1045 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1046 skb_tailroom(skb) >= copy) {
1050 if (getfrag(from, skb_put(skb, copy),
1051 offset, copy, off, skb) < 0) {
1052 __skb_trim(skb, off);
1057 int i = skb_shinfo(skb)->nr_frags;
1060 if (!sk_page_frag_refill(sk, pfrag))
1063 if (!skb_can_coalesce(skb, i, pfrag->page,
1066 if (i == MAX_SKB_FRAGS)
1069 __skb_fill_page_desc(skb, i, pfrag->page,
1071 skb_shinfo(skb)->nr_frags = ++i;
1072 get_page(pfrag->page);
1074 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1076 page_address(pfrag->page) + pfrag->offset,
1077 offset, copy, skb->len, skb) < 0)
1080 pfrag->offset += copy;
1081 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1083 skb->data_len += copy;
1084 skb->truesize += copy;
1085 refcount_add(copy, &sk->sk_wmem_alloc);
1096 cork->length -= length;
1097 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1101 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1102 struct ipcm_cookie *ipc, struct rtable **rtp)
1104 struct ip_options_rcu *opt;
1108 * setup for corking.
1113 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1115 if (unlikely(!cork->opt))
1118 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1119 cork->flags |= IPCORK_OPT;
1120 cork->addr = ipc->addr;
1126 * We steal reference to this route, caller should not release it
1129 cork->fragsize = ip_sk_use_pmtu(sk) ?
1130 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1131 cork->dst = &rt->dst;
1133 cork->ttl = ipc->ttl;
1134 cork->tos = ipc->tos;
1135 cork->priority = ipc->priority;
1136 cork->tx_flags = ipc->tx_flags;
1142 * ip_append_data() and ip_append_page() can make one large IP datagram
1143 * from many pieces of data. Each pieces will be holded on the socket
1144 * until ip_push_pending_frames() is called. Each piece can be a page
1147 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1148 * this interface potentially.
1150 * LATER: length must be adjusted by pad at tail, when it is required.
1152 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1153 int getfrag(void *from, char *to, int offset, int len,
1154 int odd, struct sk_buff *skb),
1155 void *from, int length, int transhdrlen,
1156 struct ipcm_cookie *ipc, struct rtable **rtp,
1159 struct inet_sock *inet = inet_sk(sk);
1162 if (flags&MSG_PROBE)
1165 if (skb_queue_empty(&sk->sk_write_queue)) {
1166 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1173 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1174 sk_page_frag(sk), getfrag,
1175 from, length, transhdrlen, flags);
1178 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1179 int offset, size_t size, int flags)
1181 struct inet_sock *inet = inet_sk(sk);
1182 struct sk_buff *skb;
1184 struct ip_options *opt = NULL;
1185 struct inet_cork *cork;
1190 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1195 if (flags&MSG_PROBE)
1198 if (skb_queue_empty(&sk->sk_write_queue))
1201 cork = &inet->cork.base;
1202 rt = (struct rtable *)cork->dst;
1203 if (cork->flags & IPCORK_OPT)
1206 if (!(rt->dst.dev->features&NETIF_F_SG))
1209 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1210 mtu = cork->fragsize;
1212 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1213 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1214 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1216 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1217 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1218 mtu - (opt ? opt->optlen : 0));
1222 skb = skb_peek_tail(&sk->sk_write_queue);
1226 cork->length += size;
1229 /* Check if the remaining data fits into current packet. */
1230 len = mtu - skb->len;
1232 len = maxfraglen - skb->len;
1235 struct sk_buff *skb_prev;
1239 fraggap = skb_prev->len - maxfraglen;
1241 alloclen = fragheaderlen + hh_len + fraggap + 15;
1242 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1243 if (unlikely(!skb)) {
1249 * Fill in the control structures
1251 skb->ip_summed = CHECKSUM_NONE;
1253 skb_reserve(skb, hh_len);
1256 * Find where to start putting bytes.
1258 skb_put(skb, fragheaderlen + fraggap);
1259 skb_reset_network_header(skb);
1260 skb->transport_header = (skb->network_header +
1263 skb->csum = skb_copy_and_csum_bits(skb_prev,
1265 skb_transport_header(skb),
1267 skb_prev->csum = csum_sub(skb_prev->csum,
1269 pskb_trim_unique(skb_prev, maxfraglen);
1273 * Put the packet on the pending queue.
1275 __skb_queue_tail(&sk->sk_write_queue, skb);
1282 if (skb_append_pagefrags(skb, page, offset, len)) {
1287 if (skb->ip_summed == CHECKSUM_NONE) {
1289 csum = csum_page(page, offset, len);
1290 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1294 skb->data_len += len;
1295 skb->truesize += len;
1296 refcount_add(len, &sk->sk_wmem_alloc);
1303 cork->length -= size;
1304 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1308 static void ip_cork_release(struct inet_cork *cork)
1310 cork->flags &= ~IPCORK_OPT;
1313 dst_release(cork->dst);
1318 * Combined all pending IP fragments on the socket as one IP datagram
1319 * and push them out.
1321 struct sk_buff *__ip_make_skb(struct sock *sk,
1323 struct sk_buff_head *queue,
1324 struct inet_cork *cork)
1326 struct sk_buff *skb, *tmp_skb;
1327 struct sk_buff **tail_skb;
1328 struct inet_sock *inet = inet_sk(sk);
1329 struct net *net = sock_net(sk);
1330 struct ip_options *opt = NULL;
1331 struct rtable *rt = (struct rtable *)cork->dst;
1336 skb = __skb_dequeue(queue);
1339 tail_skb = &(skb_shinfo(skb)->frag_list);
1341 /* move skb->data to ip header from ext header */
1342 if (skb->data < skb_network_header(skb))
1343 __skb_pull(skb, skb_network_offset(skb));
1344 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1345 __skb_pull(tmp_skb, skb_network_header_len(skb));
1346 *tail_skb = tmp_skb;
1347 tail_skb = &(tmp_skb->next);
1348 skb->len += tmp_skb->len;
1349 skb->data_len += tmp_skb->len;
1350 skb->truesize += tmp_skb->truesize;
1351 tmp_skb->destructor = NULL;
1355 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1356 * to fragment the frame generated here. No matter, what transforms
1357 * how transforms change size of the packet, it will come out.
1359 skb->ignore_df = ip_sk_ignore_df(sk);
1361 /* DF bit is set when we want to see DF on outgoing frames.
1362 * If ignore_df is set too, we still allow to fragment this frame
1364 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1365 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1366 (skb->len <= dst_mtu(&rt->dst) &&
1367 ip_dont_fragment(sk, &rt->dst)))
1370 if (cork->flags & IPCORK_OPT)
1375 else if (rt->rt_type == RTN_MULTICAST)
1378 ttl = ip_select_ttl(inet, &rt->dst);
1383 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1386 iph->protocol = sk->sk_protocol;
1387 ip_copy_addrs(iph, fl4);
1388 ip_select_ident(net, skb, sk);
1391 iph->ihl += opt->optlen>>2;
1392 ip_options_build(skb, opt, cork->addr, rt, 0);
1395 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1396 skb->mark = sk->sk_mark;
1398 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1402 skb_dst_set(skb, &rt->dst);
1404 if (iph->protocol == IPPROTO_ICMP)
1405 icmp_out_count(net, ((struct icmphdr *)
1406 skb_transport_header(skb))->type);
1408 ip_cork_release(cork);
1413 int ip_send_skb(struct net *net, struct sk_buff *skb)
1417 err = ip_local_out(net, skb->sk, skb);
1420 err = net_xmit_errno(err);
1422 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1428 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1430 struct sk_buff *skb;
1432 skb = ip_finish_skb(sk, fl4);
1436 /* Netfilter gets whole the not fragmented skb. */
1437 return ip_send_skb(sock_net(sk), skb);
1441 * Throw away all pending data on the socket.
1443 static void __ip_flush_pending_frames(struct sock *sk,
1444 struct sk_buff_head *queue,
1445 struct inet_cork *cork)
1447 struct sk_buff *skb;
1449 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1452 ip_cork_release(cork);
1455 void ip_flush_pending_frames(struct sock *sk)
1457 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1460 struct sk_buff *ip_make_skb(struct sock *sk,
1462 int getfrag(void *from, char *to, int offset,
1463 int len, int odd, struct sk_buff *skb),
1464 void *from, int length, int transhdrlen,
1465 struct ipcm_cookie *ipc, struct rtable **rtp,
1468 struct inet_cork cork;
1469 struct sk_buff_head queue;
1472 if (flags & MSG_PROBE)
1475 __skb_queue_head_init(&queue);
1480 err = ip_setup_cork(sk, &cork, ipc, rtp);
1482 return ERR_PTR(err);
1484 err = __ip_append_data(sk, fl4, &queue, &cork,
1485 ¤t->task_frag, getfrag,
1486 from, length, transhdrlen, flags);
1488 __ip_flush_pending_frames(sk, &queue, &cork);
1489 return ERR_PTR(err);
1492 return __ip_make_skb(sk, fl4, &queue, &cork);
1496 * Fetch data from kernel space and fill in checksum if needed.
1498 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1499 int len, int odd, struct sk_buff *skb)
1503 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1504 skb->csum = csum_block_add(skb->csum, csum, odd);
1509 * Generic function to send a packet as reply to another packet.
1510 * Used to send some TCP resets/acks so far.
1512 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1513 const struct ip_options *sopt,
1514 __be32 daddr, __be32 saddr,
1515 const struct ip_reply_arg *arg,
1518 struct ip_options_data replyopts;
1519 struct ipcm_cookie ipc;
1521 struct rtable *rt = skb_rtable(skb);
1522 struct net *net = sock_net(sk);
1523 struct sk_buff *nskb;
1527 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1536 if (replyopts.opt.opt.optlen) {
1537 ipc.opt = &replyopts.opt;
1539 if (replyopts.opt.opt.srr)
1540 daddr = replyopts.opt.opt.faddr;
1543 oif = arg->bound_dev_if;
1544 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1547 flowi4_init_output(&fl4, oif,
1548 IP4_REPLY_MARK(net, skb->mark),
1550 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1551 ip_reply_arg_flowi_flags(arg),
1553 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1555 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1556 rt = ip_route_output_key(net, &fl4);
1560 inet_sk(sk)->tos = arg->tos;
1562 sk->sk_priority = skb->priority;
1563 sk->sk_protocol = ip_hdr(skb)->protocol;
1564 sk->sk_bound_dev_if = arg->bound_dev_if;
1565 sk->sk_sndbuf = sysctl_wmem_default;
1566 sk->sk_mark = fl4.flowi4_mark;
1567 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1568 len, 0, &ipc, &rt, MSG_DONTWAIT);
1569 if (unlikely(err)) {
1570 ip_flush_pending_frames(sk);
1574 nskb = skb_peek(&sk->sk_write_queue);
1576 if (arg->csumoffset >= 0)
1577 *((__sum16 *)skb_transport_header(nskb) +
1578 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1580 nskb->ip_summed = CHECKSUM_NONE;
1581 ip_push_pending_frames(sk, &fl4);
1587 void __init ip_init(void)
1592 #if defined(CONFIG_IP_MULTICAST)