1 // SPDX-License-Identifier: GPL-2.0-only
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.
7 * The Internet Protocol (IP) output module.
10 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11 * Donald Becker, <becker@super.org>
12 * Alan Cox, <Alan.Cox@linux.org>
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>
19 * See ip_input.c for original log
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
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
43 * Hirokazu Takahashi: sendfile() on UDP works now.
46 #include <linux/uaccess.h>
47 #include <linux/module.h>
48 #include <linux/types.h>
49 #include <linux/kernel.h>
51 #include <linux/string.h>
52 #include <linux/errno.h>
53 #include <linux/highmem.h>
54 #include <linux/slab.h>
56 #include <linux/socket.h>
57 #include <linux/sockios.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>
68 #include <net/protocol.h>
69 #include <net/route.h>
71 #include <linux/skbuff.h>
75 #include <net/checksum.h>
76 #include <net/inetpeer.h>
77 #include <net/inet_ecn.h>
78 #include <net/lwtunnel.h>
79 #include <linux/bpf-cgroup.h>
80 #include <linux/igmp.h>
81 #include <linux/netfilter_ipv4.h>
82 #include <linux/netfilter_bridge.h>
83 #include <linux/netlink.h>
84 #include <linux/tcp.h>
87 ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
89 int (*output)(struct net *, struct sock *, struct sk_buff *));
91 /* Generate a checksum for an outgoing IP datagram. */
92 void ip_send_check(struct iphdr *iph)
95 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
97 EXPORT_SYMBOL(ip_send_check);
99 int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
101 struct iphdr *iph = ip_hdr(skb);
103 iph->tot_len = htons(skb->len);
106 /* if egress device is enslaved to an L3 master device pass the
107 * skb to its handler for processing
109 skb = l3mdev_ip_out(sk, skb);
113 skb->protocol = htons(ETH_P_IP);
115 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
116 net, sk, skb, NULL, skb_dst(skb)->dev,
120 int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
124 err = __ip_local_out(net, sk, skb);
125 if (likely(err == 1))
126 err = dst_output(net, sk, skb);
130 EXPORT_SYMBOL_GPL(ip_local_out);
132 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
134 int ttl = inet->uc_ttl;
137 ttl = ip4_dst_hoplimit(dst);
142 * Add an ip header to a skbuff and send it out.
145 int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
146 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt,
149 struct inet_sock *inet = inet_sk(sk);
150 struct rtable *rt = skb_rtable(skb);
151 struct net *net = sock_net(sk);
154 /* Build the IP header. */
155 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
156 skb_reset_network_header(skb);
161 iph->ttl = ip_select_ttl(inet, &rt->dst);
162 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
164 iph->protocol = sk->sk_protocol;
165 if (ip_dont_fragment(sk, &rt->dst)) {
166 iph->frag_off = htons(IP_DF);
170 __ip_select_ident(net, iph, 1);
173 if (opt && opt->opt.optlen) {
174 iph->ihl += opt->opt.optlen>>2;
175 ip_options_build(skb, &opt->opt, daddr, rt, 0);
178 skb->priority = sk->sk_priority;
180 skb->mark = sk->sk_mark;
183 return ip_local_out(net, skb->sk, skb);
185 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
187 static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
189 struct dst_entry *dst = skb_dst(skb);
190 struct rtable *rt = (struct rtable *)dst;
191 struct net_device *dev = dst->dev;
192 unsigned int hh_len = LL_RESERVED_SPACE(dev);
193 struct neighbour *neigh;
194 bool is_v6gw = false;
196 if (rt->rt_type == RTN_MULTICAST) {
197 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
198 } else if (rt->rt_type == RTN_BROADCAST)
199 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
201 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
202 skb = skb_expand_head(skb, hh_len);
207 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
208 int res = lwtunnel_xmit(skb);
210 if (res < 0 || res == LWTUNNEL_XMIT_DONE)
215 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
216 if (!IS_ERR(neigh)) {
219 sock_confirm_neigh(skb, neigh);
220 /* if crossing protocols, can not use the cached header */
221 res = neigh_output(neigh, skb, is_v6gw);
222 rcu_read_unlock_bh();
225 rcu_read_unlock_bh();
227 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
233 static int ip_finish_output_gso(struct net *net, struct sock *sk,
234 struct sk_buff *skb, unsigned int mtu)
236 struct sk_buff *segs, *nskb;
237 netdev_features_t features;
240 /* common case: seglen is <= mtu
242 if (skb_gso_validate_network_len(skb, mtu))
243 return ip_finish_output2(net, sk, skb);
245 /* Slowpath - GSO segment length exceeds the egress MTU.
247 * This can happen in several cases:
248 * - Forwarding of a TCP GRO skb, when DF flag is not set.
249 * - Forwarding of an skb that arrived on a virtualization interface
250 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
252 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
253 * interface with a smaller MTU.
254 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
255 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
258 features = netif_skb_features(skb);
259 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
260 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
261 if (IS_ERR_OR_NULL(segs)) {
268 skb_list_walk_safe(segs, segs, nskb) {
271 skb_mark_not_on_list(segs);
272 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
281 static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
285 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
286 /* Policy lookup after SNAT yielded a new policy */
287 if (skb_dst(skb)->xfrm) {
288 IPCB(skb)->flags |= IPSKB_REROUTED;
289 return dst_output(net, sk, skb);
292 mtu = ip_skb_dst_mtu(sk, skb);
294 return ip_finish_output_gso(net, sk, skb, mtu);
296 if (skb->len > mtu || IPCB(skb)->frag_max_size)
297 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
299 return ip_finish_output2(net, sk, skb);
302 static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
306 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
308 case NET_XMIT_SUCCESS:
309 return __ip_finish_output(net, sk, skb);
311 return __ip_finish_output(net, sk, skb) ? : ret;
318 static int ip_mc_finish_output(struct net *net, struct sock *sk,
321 struct rtable *new_rt;
325 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
330 case NET_XMIT_SUCCESS:
337 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
338 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
339 * see ipv4_pktinfo_prepare().
341 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
345 skb_dst_set(skb, &new_rt->dst);
348 err = dev_loopback_xmit(net, sk, skb);
349 return (do_cn && err) ? ret : err;
352 int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
354 struct rtable *rt = skb_rtable(skb);
355 struct net_device *dev = rt->dst.dev;
358 * If the indicated interface is up and running, send the packet.
360 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
363 skb->protocol = htons(ETH_P_IP);
366 * Multicasts are looped back for other local users
369 if (rt->rt_flags&RTCF_MULTICAST) {
371 #ifdef CONFIG_IP_MROUTE
372 /* Small optimization: do not loopback not local frames,
373 which returned after forwarding; they will be dropped
374 by ip_mr_input in any case.
375 Note, that local frames are looped back to be delivered
378 This check is duplicated in ip_mr_input at the moment.
381 ((rt->rt_flags & RTCF_LOCAL) ||
382 !(IPCB(skb)->flags & IPSKB_FORWARDED))
385 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
387 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
388 net, sk, newskb, NULL, newskb->dev,
389 ip_mc_finish_output);
392 /* Multicasts with ttl 0 must not go beyond the host */
394 if (ip_hdr(skb)->ttl == 0) {
400 if (rt->rt_flags&RTCF_BROADCAST) {
401 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
403 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
404 net, sk, newskb, NULL, newskb->dev,
405 ip_mc_finish_output);
408 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
409 net, sk, skb, NULL, skb->dev,
411 !(IPCB(skb)->flags & IPSKB_REROUTED));
414 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
416 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
418 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
421 skb->protocol = htons(ETH_P_IP);
423 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
424 net, sk, skb, indev, dev,
426 !(IPCB(skb)->flags & IPSKB_REROUTED));
428 EXPORT_SYMBOL(ip_output);
431 * copy saddr and daddr, possibly using 64bit load/stores
433 * iph->saddr = fl4->saddr;
434 * iph->daddr = fl4->daddr;
436 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
438 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
439 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
441 iph->saddr = fl4->saddr;
442 iph->daddr = fl4->daddr;
445 /* Note: skb->sk can be different from sk, in case of tunnels */
446 int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
449 struct inet_sock *inet = inet_sk(sk);
450 struct net *net = sock_net(sk);
451 struct ip_options_rcu *inet_opt;
457 /* Skip all of this if the packet is already routed,
458 * f.e. by something like SCTP.
461 inet_opt = rcu_dereference(inet->inet_opt);
463 rt = skb_rtable(skb);
467 /* Make sure we can route this packet. */
468 rt = (struct rtable *)__sk_dst_check(sk, 0);
472 /* Use correct destination address if we have options. */
473 daddr = inet->inet_daddr;
474 if (inet_opt && inet_opt->opt.srr)
475 daddr = inet_opt->opt.faddr;
477 /* If this fails, retransmit mechanism of transport layer will
478 * keep trying until route appears or the connection times
481 rt = ip_route_output_ports(net, fl4, sk,
482 daddr, inet->inet_saddr,
486 RT_CONN_FLAGS_TOS(sk, tos),
487 sk->sk_bound_dev_if);
490 sk_setup_caps(sk, &rt->dst);
492 skb_dst_set_noref(skb, &rt->dst);
495 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
498 /* OK, we know where to send it, allocate and build IP header. */
499 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
500 skb_reset_network_header(skb);
502 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
503 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
504 iph->frag_off = htons(IP_DF);
507 iph->ttl = ip_select_ttl(inet, &rt->dst);
508 iph->protocol = sk->sk_protocol;
509 ip_copy_addrs(iph, fl4);
511 /* Transport layer set skb->h.foo itself. */
513 if (inet_opt && inet_opt->opt.optlen) {
514 iph->ihl += inet_opt->opt.optlen >> 2;
515 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
518 ip_select_ident_segs(net, skb, sk,
519 skb_shinfo(skb)->gso_segs ?: 1);
521 /* TODO : should we use skb->sk here instead of sk ? */
522 skb->priority = sk->sk_priority;
523 skb->mark = sk->sk_mark;
525 res = ip_local_out(net, sk, skb);
531 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
533 return -EHOSTUNREACH;
535 EXPORT_SYMBOL(__ip_queue_xmit);
537 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
539 return __ip_queue_xmit(sk, skb, fl, inet_sk(sk)->tos);
541 EXPORT_SYMBOL(ip_queue_xmit);
543 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
545 to->pkt_type = from->pkt_type;
546 to->priority = from->priority;
547 to->protocol = from->protocol;
548 to->skb_iif = from->skb_iif;
550 skb_dst_copy(to, from);
552 to->mark = from->mark;
554 skb_copy_hash(to, from);
556 #ifdef CONFIG_NET_SCHED
557 to->tc_index = from->tc_index;
560 skb_ext_copy(to, from);
561 #if IS_ENABLED(CONFIG_IP_VS)
562 to->ipvs_property = from->ipvs_property;
564 skb_copy_secmark(to, from);
567 static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
569 int (*output)(struct net *, struct sock *, struct sk_buff *))
571 struct iphdr *iph = ip_hdr(skb);
573 if ((iph->frag_off & htons(IP_DF)) == 0)
574 return ip_do_fragment(net, sk, skb, output);
576 if (unlikely(!skb->ignore_df ||
577 (IPCB(skb)->frag_max_size &&
578 IPCB(skb)->frag_max_size > mtu))) {
579 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
580 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
586 return ip_do_fragment(net, sk, skb, output);
589 void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
590 unsigned int hlen, struct ip_fraglist_iter *iter)
592 unsigned int first_len = skb_pagelen(skb);
594 iter->frag = skb_shinfo(skb)->frag_list;
595 skb_frag_list_init(skb);
601 skb->data_len = first_len - skb_headlen(skb);
602 skb->len = first_len;
603 iph->tot_len = htons(first_len);
604 iph->frag_off = htons(IP_MF);
607 EXPORT_SYMBOL(ip_fraglist_init);
609 void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
611 unsigned int hlen = iter->hlen;
612 struct iphdr *iph = iter->iph;
613 struct sk_buff *frag;
616 frag->ip_summed = CHECKSUM_NONE;
617 skb_reset_transport_header(frag);
618 __skb_push(frag, hlen);
619 skb_reset_network_header(frag);
620 memcpy(skb_network_header(frag), iph, hlen);
621 iter->iph = ip_hdr(frag);
623 iph->tot_len = htons(frag->len);
624 ip_copy_metadata(frag, skb);
625 iter->offset += skb->len - hlen;
626 iph->frag_off = htons(iter->offset >> 3);
628 iph->frag_off |= htons(IP_MF);
629 /* Ready, complete checksum */
632 EXPORT_SYMBOL(ip_fraglist_prepare);
634 void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
635 unsigned int ll_rs, unsigned int mtu, bool DF,
636 struct ip_frag_state *state)
638 struct iphdr *iph = ip_hdr(skb);
642 state->ll_rs = ll_rs;
645 state->left = skb->len - hlen; /* Space per frame */
646 state->ptr = hlen; /* Where to start from */
648 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
649 state->not_last_frag = iph->frag_off & htons(IP_MF);
651 EXPORT_SYMBOL(ip_frag_init);
653 static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
656 /* Copy the flags to each fragment. */
657 IPCB(to)->flags = IPCB(from)->flags;
659 /* ANK: dirty, but effective trick. Upgrade options only if
660 * the segment to be fragmented was THE FIRST (otherwise,
661 * options are already fixed) and make it ONCE
662 * on the initial skb, so that all the following fragments
663 * will inherit fixed options.
666 ip_options_fragment(from);
669 struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
671 unsigned int len = state->left;
672 struct sk_buff *skb2;
676 /* IF: it doesn't fit, use 'mtu' - the data space left */
677 if (len > state->mtu)
679 /* IF: we are not sending up to and including the packet end
680 then align the next start on an eight byte boundary */
681 if (len < state->left) {
685 /* Allocate buffer */
686 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
688 return ERR_PTR(-ENOMEM);
691 * Set up data on packet
694 ip_copy_metadata(skb2, skb);
695 skb_reserve(skb2, state->ll_rs);
696 skb_put(skb2, len + state->hlen);
697 skb_reset_network_header(skb2);
698 skb2->transport_header = skb2->network_header + state->hlen;
701 * Charge the memory for the fragment to any owner
706 skb_set_owner_w(skb2, skb->sk);
709 * Copy the packet header into the new buffer.
712 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
715 * Copy a block of the IP datagram.
717 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
722 * Fill in the new header fields.
725 iph->frag_off = htons((state->offset >> 3));
727 iph->frag_off |= htons(IP_DF);
730 * Added AC : If we are fragmenting a fragment that's not the
731 * last fragment then keep MF on each bit
733 if (state->left > 0 || state->not_last_frag)
734 iph->frag_off |= htons(IP_MF);
736 state->offset += len;
738 iph->tot_len = htons(len + state->hlen);
744 EXPORT_SYMBOL(ip_frag_next);
747 * This IP datagram is too large to be sent in one piece. Break it up into
748 * smaller pieces (each of size equal to IP header plus
749 * a block of the data of the original IP data part) that will yet fit in a
750 * single device frame, and queue such a frame for sending.
753 int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
754 int (*output)(struct net *, struct sock *, struct sk_buff *))
757 struct sk_buff *skb2;
758 struct rtable *rt = skb_rtable(skb);
759 unsigned int mtu, hlen, ll_rs;
760 struct ip_fraglist_iter iter;
761 ktime_t tstamp = skb->tstamp;
762 struct ip_frag_state state;
765 /* for offloaded checksums cleanup checksum before fragmentation */
766 if (skb->ip_summed == CHECKSUM_PARTIAL &&
767 (err = skb_checksum_help(skb)))
771 * Point into the IP datagram header.
776 mtu = ip_skb_dst_mtu(sk, skb);
777 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
778 mtu = IPCB(skb)->frag_max_size;
781 * Setup starting values.
785 mtu = mtu - hlen; /* Size of data space */
786 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
787 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
789 /* When frag_list is given, use it. First, check its validity:
790 * some transformers could create wrong frag_list or break existing
791 * one, it is not prohibited. In this case fall back to copying.
793 * LATER: this step can be merged to real generation of fragments,
794 * we can switch to copy when see the first bad fragment.
796 if (skb_has_frag_list(skb)) {
797 struct sk_buff *frag, *frag2;
798 unsigned int first_len = skb_pagelen(skb);
800 if (first_len - hlen > mtu ||
801 ((first_len - hlen) & 7) ||
802 ip_is_fragment(iph) ||
804 skb_headroom(skb) < ll_rs)
807 skb_walk_frags(skb, frag) {
808 /* Correct geometry. */
809 if (frag->len > mtu ||
810 ((frag->len & 7) && frag->next) ||
811 skb_headroom(frag) < hlen + ll_rs)
812 goto slow_path_clean;
814 /* Partially cloned skb? */
815 if (skb_shared(frag))
816 goto slow_path_clean;
821 frag->destructor = sock_wfree;
823 skb->truesize -= frag->truesize;
826 /* Everything is OK. Generate! */
827 ip_fraglist_init(skb, iph, hlen, &iter);
828 ip_options_fragment(iter.frag);
831 /* Prepare header of the next frame,
832 * before previous one went down. */
834 IPCB(iter.frag)->flags = IPCB(skb)->flags;
835 ip_fraglist_prepare(skb, &iter);
838 skb->tstamp = tstamp;
839 err = output(net, sk, skb);
842 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
843 if (err || !iter.frag)
846 skb = ip_fraglist_next(&iter);
850 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
854 kfree_skb_list(iter.frag);
856 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
860 skb_walk_frags(skb, frag2) {
864 frag2->destructor = NULL;
865 skb->truesize += frag2->truesize;
871 * Fragment the datagram.
874 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
878 * Keep copying data until we run out.
881 while (state.left > 0) {
882 bool first_frag = (state.offset == 0);
884 skb2 = ip_frag_next(skb, &state);
889 ip_frag_ipcb(skb, skb2, first_frag);
892 * Put this fragment into the sending queue.
894 skb2->tstamp = tstamp;
895 err = output(net, sk, skb2);
899 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
902 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
907 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
910 EXPORT_SYMBOL(ip_do_fragment);
913 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
915 struct msghdr *msg = from;
917 if (skb->ip_summed == CHECKSUM_PARTIAL) {
918 if (!copy_from_iter_full(to, len, &msg->msg_iter))
922 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
924 skb->csum = csum_block_add(skb->csum, csum, odd);
928 EXPORT_SYMBOL(ip_generic_getfrag);
931 csum_page(struct page *page, int offset, int copy)
936 csum = csum_partial(kaddr + offset, copy, 0);
941 static int __ip_append_data(struct sock *sk,
943 struct sk_buff_head *queue,
944 struct inet_cork *cork,
945 struct page_frag *pfrag,
946 int getfrag(void *from, char *to, int offset,
947 int len, int odd, struct sk_buff *skb),
948 void *from, int length, int transhdrlen,
951 struct inet_sock *inet = inet_sk(sk);
952 struct ubuf_info *uarg = NULL;
955 struct ip_options *opt = cork->opt;
962 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
963 int csummode = CHECKSUM_NONE;
964 struct rtable *rt = (struct rtable *)cork->dst;
965 unsigned int wmem_alloc_delta = 0;
966 bool paged, extra_uref = false;
969 skb = skb_peek_tail(queue);
971 exthdrlen = !skb ? rt->dst.header_len : 0;
972 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
973 paged = !!cork->gso_size;
975 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
976 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
977 tskey = sk->sk_tskey++;
979 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
981 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
982 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
983 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu;
985 if (cork->length + length > maxnonfragsize - fragheaderlen) {
986 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
987 mtu - (opt ? opt->optlen : 0));
992 * transhdrlen > 0 means that this is the first fragment and we wish
993 * it won't be fragmented in the future.
996 length + fragheaderlen <= mtu &&
997 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
998 (!(flags & MSG_MORE) || cork->gso_size) &&
999 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
1000 csummode = CHECKSUM_PARTIAL;
1002 if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) {
1003 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
1006 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
1007 if (rt->dst.dev->features & NETIF_F_SG &&
1008 csummode == CHECKSUM_PARTIAL) {
1012 skb_zcopy_set(skb, uarg, &extra_uref);
1016 cork->length += length;
1018 /* So, what's going on in the loop below?
1020 * We use calculated fragment length to generate chained skb,
1021 * each of segments is IP fragment ready for sending to network after
1022 * adding appropriate IP header.
1028 while (length > 0) {
1029 /* Check if the remaining data fits into current packet. */
1030 copy = mtu - skb->len;
1032 copy = maxfraglen - skb->len;
1035 unsigned int datalen;
1036 unsigned int fraglen;
1037 unsigned int fraggap;
1038 unsigned int alloclen, alloc_extra;
1039 unsigned int pagedlen;
1040 struct sk_buff *skb_prev;
1044 fraggap = skb_prev->len - maxfraglen;
1049 * If remaining data exceeds the mtu,
1050 * we know we need more fragment(s).
1052 datalen = length + fraggap;
1053 if (datalen > mtu - fragheaderlen)
1054 datalen = maxfraglen - fragheaderlen;
1055 fraglen = datalen + fragheaderlen;
1058 alloc_extra = hh_len + 15;
1059 alloc_extra += exthdrlen;
1061 /* The last fragment gets additional space at tail.
1062 * Note, with MSG_MORE we overallocate on fragments,
1063 * because we have no idea what fragment will be
1066 if (datalen == length + fraggap)
1067 alloc_extra += rt->dst.trailer_len;
1069 if ((flags & MSG_MORE) &&
1070 !(rt->dst.dev->features&NETIF_F_SG))
1073 (fraglen + alloc_extra < SKB_MAX_ALLOC ||
1074 !(rt->dst.dev->features & NETIF_F_SG)))
1077 alloclen = min_t(int, fraglen, MAX_HEADER);
1078 pagedlen = fraglen - alloclen;
1081 alloclen += alloc_extra;
1084 skb = sock_alloc_send_skb(sk, alloclen,
1085 (flags & MSG_DONTWAIT), &err);
1088 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1090 skb = alloc_skb(alloclen,
1099 * Fill in the control structures
1101 skb->ip_summed = csummode;
1103 skb_reserve(skb, hh_len);
1106 * Find where to start putting bytes.
1108 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1109 skb_set_network_header(skb, exthdrlen);
1110 skb->transport_header = (skb->network_header +
1112 data += fragheaderlen + exthdrlen;
1115 skb->csum = skb_copy_and_csum_bits(
1116 skb_prev, maxfraglen,
1117 data + transhdrlen, fraggap);
1118 skb_prev->csum = csum_sub(skb_prev->csum,
1121 pskb_trim_unique(skb_prev, maxfraglen);
1124 copy = datalen - transhdrlen - fraggap - pagedlen;
1125 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1132 length -= copy + transhdrlen;
1135 csummode = CHECKSUM_NONE;
1137 /* only the initial fragment is time stamped */
1138 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1140 skb_shinfo(skb)->tskey = tskey;
1142 skb_zcopy_set(skb, uarg, &extra_uref);
1144 if ((flags & MSG_CONFIRM) && !skb_prev)
1145 skb_set_dst_pending_confirm(skb, 1);
1148 * Put the packet on the pending queue.
1150 if (!skb->destructor) {
1151 skb->destructor = sock_wfree;
1153 wmem_alloc_delta += skb->truesize;
1155 __skb_queue_tail(queue, skb);
1162 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1163 skb_tailroom(skb) >= copy) {
1167 if (getfrag(from, skb_put(skb, copy),
1168 offset, copy, off, skb) < 0) {
1169 __skb_trim(skb, off);
1173 } else if (!uarg || !uarg->zerocopy) {
1174 int i = skb_shinfo(skb)->nr_frags;
1177 if (!sk_page_frag_refill(sk, pfrag))
1180 if (!skb_can_coalesce(skb, i, pfrag->page,
1183 if (i == MAX_SKB_FRAGS)
1186 __skb_fill_page_desc(skb, i, pfrag->page,
1188 skb_shinfo(skb)->nr_frags = ++i;
1189 get_page(pfrag->page);
1191 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1193 page_address(pfrag->page) + pfrag->offset,
1194 offset, copy, skb->len, skb) < 0)
1197 pfrag->offset += copy;
1198 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1200 skb->data_len += copy;
1201 skb->truesize += copy;
1202 wmem_alloc_delta += copy;
1204 err = skb_zerocopy_iter_dgram(skb, from, copy);
1212 if (wmem_alloc_delta)
1213 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1219 net_zcopy_put_abort(uarg, extra_uref);
1220 cork->length -= length;
1221 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1222 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1226 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1227 struct ipcm_cookie *ipc, struct rtable **rtp)
1229 struct ip_options_rcu *opt;
1237 * setup for corking.
1242 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1244 if (unlikely(!cork->opt))
1247 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1248 cork->flags |= IPCORK_OPT;
1249 cork->addr = ipc->addr;
1252 cork->fragsize = ip_sk_use_pmtu(sk) ?
1253 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
1255 if (!inetdev_valid_mtu(cork->fragsize))
1256 return -ENETUNREACH;
1258 cork->gso_size = ipc->gso_size;
1260 cork->dst = &rt->dst;
1261 /* We stole this route, caller should not release it. */
1265 cork->ttl = ipc->ttl;
1266 cork->tos = ipc->tos;
1267 cork->mark = ipc->sockc.mark;
1268 cork->priority = ipc->priority;
1269 cork->transmit_time = ipc->sockc.transmit_time;
1271 sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags);
1277 * ip_append_data() and ip_append_page() can make one large IP datagram
1278 * from many pieces of data. Each pieces will be holded on the socket
1279 * until ip_push_pending_frames() is called. Each piece can be a page
1282 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1283 * this interface potentially.
1285 * LATER: length must be adjusted by pad at tail, when it is required.
1287 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1288 int getfrag(void *from, char *to, int offset, int len,
1289 int odd, struct sk_buff *skb),
1290 void *from, int length, int transhdrlen,
1291 struct ipcm_cookie *ipc, struct rtable **rtp,
1294 struct inet_sock *inet = inet_sk(sk);
1297 if (flags&MSG_PROBE)
1300 if (skb_queue_empty(&sk->sk_write_queue)) {
1301 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1308 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1309 sk_page_frag(sk), getfrag,
1310 from, length, transhdrlen, flags);
1313 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1314 int offset, size_t size, int flags)
1316 struct inet_sock *inet = inet_sk(sk);
1317 struct sk_buff *skb;
1319 struct ip_options *opt = NULL;
1320 struct inet_cork *cork;
1325 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1330 if (flags&MSG_PROBE)
1333 if (skb_queue_empty(&sk->sk_write_queue))
1336 cork = &inet->cork.base;
1337 rt = (struct rtable *)cork->dst;
1338 if (cork->flags & IPCORK_OPT)
1341 if (!(rt->dst.dev->features & NETIF_F_SG))
1344 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1345 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
1347 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1348 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1349 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1351 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1352 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1353 mtu - (opt ? opt->optlen : 0));
1357 skb = skb_peek_tail(&sk->sk_write_queue);
1361 cork->length += size;
1364 /* Check if the remaining data fits into current packet. */
1365 len = mtu - skb->len;
1367 len = maxfraglen - skb->len;
1370 struct sk_buff *skb_prev;
1374 fraggap = skb_prev->len - maxfraglen;
1376 alloclen = fragheaderlen + hh_len + fraggap + 15;
1377 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1378 if (unlikely(!skb)) {
1384 * Fill in the control structures
1386 skb->ip_summed = CHECKSUM_NONE;
1388 skb_reserve(skb, hh_len);
1391 * Find where to start putting bytes.
1393 skb_put(skb, fragheaderlen + fraggap);
1394 skb_reset_network_header(skb);
1395 skb->transport_header = (skb->network_header +
1398 skb->csum = skb_copy_and_csum_bits(skb_prev,
1400 skb_transport_header(skb),
1402 skb_prev->csum = csum_sub(skb_prev->csum,
1404 pskb_trim_unique(skb_prev, maxfraglen);
1408 * Put the packet on the pending queue.
1410 __skb_queue_tail(&sk->sk_write_queue, skb);
1417 if (skb_append_pagefrags(skb, page, offset, len)) {
1422 if (skb->ip_summed == CHECKSUM_NONE) {
1424 csum = csum_page(page, offset, len);
1425 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1429 skb->data_len += len;
1430 skb->truesize += len;
1431 refcount_add(len, &sk->sk_wmem_alloc);
1438 cork->length -= size;
1439 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1443 static void ip_cork_release(struct inet_cork *cork)
1445 cork->flags &= ~IPCORK_OPT;
1448 dst_release(cork->dst);
1453 * Combined all pending IP fragments on the socket as one IP datagram
1454 * and push them out.
1456 struct sk_buff *__ip_make_skb(struct sock *sk,
1458 struct sk_buff_head *queue,
1459 struct inet_cork *cork)
1461 struct sk_buff *skb, *tmp_skb;
1462 struct sk_buff **tail_skb;
1463 struct inet_sock *inet = inet_sk(sk);
1464 struct net *net = sock_net(sk);
1465 struct ip_options *opt = NULL;
1466 struct rtable *rt = (struct rtable *)cork->dst;
1471 skb = __skb_dequeue(queue);
1474 tail_skb = &(skb_shinfo(skb)->frag_list);
1476 /* move skb->data to ip header from ext header */
1477 if (skb->data < skb_network_header(skb))
1478 __skb_pull(skb, skb_network_offset(skb));
1479 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1480 __skb_pull(tmp_skb, skb_network_header_len(skb));
1481 *tail_skb = tmp_skb;
1482 tail_skb = &(tmp_skb->next);
1483 skb->len += tmp_skb->len;
1484 skb->data_len += tmp_skb->len;
1485 skb->truesize += tmp_skb->truesize;
1486 tmp_skb->destructor = NULL;
1490 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1491 * to fragment the frame generated here. No matter, what transforms
1492 * how transforms change size of the packet, it will come out.
1494 skb->ignore_df = ip_sk_ignore_df(sk);
1496 /* DF bit is set when we want to see DF on outgoing frames.
1497 * If ignore_df is set too, we still allow to fragment this frame
1499 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1500 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1501 (skb->len <= dst_mtu(&rt->dst) &&
1502 ip_dont_fragment(sk, &rt->dst)))
1505 if (cork->flags & IPCORK_OPT)
1510 else if (rt->rt_type == RTN_MULTICAST)
1513 ttl = ip_select_ttl(inet, &rt->dst);
1518 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1521 iph->protocol = sk->sk_protocol;
1522 ip_copy_addrs(iph, fl4);
1523 ip_select_ident(net, skb, sk);
1526 iph->ihl += opt->optlen >> 2;
1527 ip_options_build(skb, opt, cork->addr, rt, 0);
1530 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1531 skb->mark = cork->mark;
1532 skb->tstamp = cork->transmit_time;
1534 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1538 skb_dst_set(skb, &rt->dst);
1540 if (iph->protocol == IPPROTO_ICMP)
1541 icmp_out_count(net, ((struct icmphdr *)
1542 skb_transport_header(skb))->type);
1544 ip_cork_release(cork);
1549 int ip_send_skb(struct net *net, struct sk_buff *skb)
1553 err = ip_local_out(net, skb->sk, skb);
1556 err = net_xmit_errno(err);
1558 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1564 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1566 struct sk_buff *skb;
1568 skb = ip_finish_skb(sk, fl4);
1572 /* Netfilter gets whole the not fragmented skb. */
1573 return ip_send_skb(sock_net(sk), skb);
1577 * Throw away all pending data on the socket.
1579 static void __ip_flush_pending_frames(struct sock *sk,
1580 struct sk_buff_head *queue,
1581 struct inet_cork *cork)
1583 struct sk_buff *skb;
1585 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1588 ip_cork_release(cork);
1591 void ip_flush_pending_frames(struct sock *sk)
1593 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1596 struct sk_buff *ip_make_skb(struct sock *sk,
1598 int getfrag(void *from, char *to, int offset,
1599 int len, int odd, struct sk_buff *skb),
1600 void *from, int length, int transhdrlen,
1601 struct ipcm_cookie *ipc, struct rtable **rtp,
1602 struct inet_cork *cork, unsigned int flags)
1604 struct sk_buff_head queue;
1607 if (flags & MSG_PROBE)
1610 __skb_queue_head_init(&queue);
1615 err = ip_setup_cork(sk, cork, ipc, rtp);
1617 return ERR_PTR(err);
1619 err = __ip_append_data(sk, fl4, &queue, cork,
1620 ¤t->task_frag, getfrag,
1621 from, length, transhdrlen, flags);
1623 __ip_flush_pending_frames(sk, &queue, cork);
1624 return ERR_PTR(err);
1627 return __ip_make_skb(sk, fl4, &queue, cork);
1631 * Fetch data from kernel space and fill in checksum if needed.
1633 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1634 int len, int odd, struct sk_buff *skb)
1638 csum = csum_partial_copy_nocheck(dptr+offset, to, len);
1639 skb->csum = csum_block_add(skb->csum, csum, odd);
1644 * Generic function to send a packet as reply to another packet.
1645 * Used to send some TCP resets/acks so far.
1647 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1648 const struct ip_options *sopt,
1649 __be32 daddr, __be32 saddr,
1650 const struct ip_reply_arg *arg,
1651 unsigned int len, u64 transmit_time)
1653 struct ip_options_data replyopts;
1654 struct ipcm_cookie ipc;
1656 struct rtable *rt = skb_rtable(skb);
1657 struct net *net = sock_net(sk);
1658 struct sk_buff *nskb;
1662 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1667 ipc.sockc.transmit_time = transmit_time;
1669 if (replyopts.opt.opt.optlen) {
1670 ipc.opt = &replyopts.opt;
1672 if (replyopts.opt.opt.srr)
1673 daddr = replyopts.opt.opt.faddr;
1676 oif = arg->bound_dev_if;
1677 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1680 flowi4_init_output(&fl4, oif,
1681 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1683 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1684 ip_reply_arg_flowi_flags(arg),
1686 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1688 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
1689 rt = ip_route_output_key(net, &fl4);
1693 inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK;
1695 sk->sk_protocol = ip_hdr(skb)->protocol;
1696 sk->sk_bound_dev_if = arg->bound_dev_if;
1697 sk->sk_sndbuf = sysctl_wmem_default;
1698 ipc.sockc.mark = fl4.flowi4_mark;
1699 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1700 len, 0, &ipc, &rt, MSG_DONTWAIT);
1701 if (unlikely(err)) {
1702 ip_flush_pending_frames(sk);
1706 nskb = skb_peek(&sk->sk_write_queue);
1708 if (arg->csumoffset >= 0)
1709 *((__sum16 *)skb_transport_header(nskb) +
1710 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1712 nskb->ip_summed = CHECKSUM_NONE;
1713 ip_push_pending_frames(sk, &fl4);
1719 void __init ip_init(void)
1724 #if defined(CONFIG_IP_MULTICAST)