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 /* Be paranoid, rather than too clever. */
202 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
203 struct sk_buff *skb2;
205 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
211 skb_set_owner_w(skb2, skb->sk);
216 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
217 int res = lwtunnel_xmit(skb);
219 if (res < 0 || res == LWTUNNEL_XMIT_DONE)
224 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
225 if (!IS_ERR(neigh)) {
228 sock_confirm_neigh(skb, neigh);
229 /* if crossing protocols, can not use the cached header */
230 res = neigh_output(neigh, skb, is_v6gw);
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 struct sk_buff *segs, *nskb;
246 netdev_features_t features;
249 /* common case: seglen is <= mtu
251 if (skb_gso_validate_network_len(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_GSO_CB_OFFSET);
269 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
270 if (IS_ERR_OR_NULL(segs)) {
277 skb_list_walk_safe(segs, segs, nskb) {
280 skb_mark_not_on_list(segs);
281 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
290 static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
294 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
295 /* Policy lookup after SNAT yielded a new policy */
296 if (skb_dst(skb)->xfrm) {
297 IPCB(skb)->flags |= IPSKB_REROUTED;
298 return dst_output(net, sk, skb);
301 mtu = ip_skb_dst_mtu(sk, skb);
303 return ip_finish_output_gso(net, sk, skb, mtu);
305 if (skb->len > mtu || IPCB(skb)->frag_max_size)
306 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
308 return ip_finish_output2(net, sk, skb);
311 static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
315 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
317 case NET_XMIT_SUCCESS:
318 return __ip_finish_output(net, sk, skb);
320 return __ip_finish_output(net, sk, skb) ? : ret;
327 static int ip_mc_finish_output(struct net *net, struct sock *sk,
330 struct rtable *new_rt;
334 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
339 case NET_XMIT_SUCCESS:
346 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
347 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
348 * see ipv4_pktinfo_prepare().
350 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
354 skb_dst_set(skb, &new_rt->dst);
357 err = dev_loopback_xmit(net, sk, skb);
358 return (do_cn && err) ? ret : err;
361 int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
363 struct rtable *rt = skb_rtable(skb);
364 struct net_device *dev = rt->dst.dev;
367 * If the indicated interface is up and running, send the packet.
369 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
372 skb->protocol = htons(ETH_P_IP);
375 * Multicasts are looped back for other local users
378 if (rt->rt_flags&RTCF_MULTICAST) {
380 #ifdef CONFIG_IP_MROUTE
381 /* Small optimization: do not loopback not local frames,
382 which returned after forwarding; they will be dropped
383 by ip_mr_input in any case.
384 Note, that local frames are looped back to be delivered
387 This check is duplicated in ip_mr_input at the moment.
390 ((rt->rt_flags & RTCF_LOCAL) ||
391 !(IPCB(skb)->flags & IPSKB_FORWARDED))
394 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
396 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
397 net, sk, newskb, NULL, newskb->dev,
398 ip_mc_finish_output);
401 /* Multicasts with ttl 0 must not go beyond the host */
403 if (ip_hdr(skb)->ttl == 0) {
409 if (rt->rt_flags&RTCF_BROADCAST) {
410 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
412 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
413 net, sk, newskb, NULL, newskb->dev,
414 ip_mc_finish_output);
417 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
418 net, sk, skb, NULL, skb->dev,
420 !(IPCB(skb)->flags & IPSKB_REROUTED));
423 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
425 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
427 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
430 skb->protocol = htons(ETH_P_IP);
432 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
433 net, sk, skb, indev, dev,
435 !(IPCB(skb)->flags & IPSKB_REROUTED));
437 EXPORT_SYMBOL(ip_output);
440 * copy saddr and daddr, possibly using 64bit load/stores
442 * iph->saddr = fl4->saddr;
443 * iph->daddr = fl4->daddr;
445 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
447 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
448 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
449 memcpy(&iph->saddr, &fl4->saddr,
450 sizeof(fl4->saddr) + sizeof(fl4->daddr));
453 /* Note: skb->sk can be different from sk, in case of tunnels */
454 int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
457 struct inet_sock *inet = inet_sk(sk);
458 struct net *net = sock_net(sk);
459 struct ip_options_rcu *inet_opt;
465 /* Skip all of this if the packet is already routed,
466 * f.e. by something like SCTP.
469 inet_opt = rcu_dereference(inet->inet_opt);
471 rt = skb_rtable(skb);
475 /* Make sure we can route this packet. */
476 rt = (struct rtable *)__sk_dst_check(sk, 0);
480 /* Use correct destination address if we have options. */
481 daddr = inet->inet_daddr;
482 if (inet_opt && inet_opt->opt.srr)
483 daddr = inet_opt->opt.faddr;
485 /* If this fails, retransmit mechanism of transport layer will
486 * keep trying until route appears or the connection times
489 rt = ip_route_output_ports(net, fl4, sk,
490 daddr, inet->inet_saddr,
494 RT_CONN_FLAGS_TOS(sk, tos),
495 sk->sk_bound_dev_if);
498 sk_setup_caps(sk, &rt->dst);
500 skb_dst_set_noref(skb, &rt->dst);
503 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
506 /* OK, we know where to send it, allocate and build IP header. */
507 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
508 skb_reset_network_header(skb);
510 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
511 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
512 iph->frag_off = htons(IP_DF);
515 iph->ttl = ip_select_ttl(inet, &rt->dst);
516 iph->protocol = sk->sk_protocol;
517 ip_copy_addrs(iph, fl4);
519 /* Transport layer set skb->h.foo itself. */
521 if (inet_opt && inet_opt->opt.optlen) {
522 iph->ihl += inet_opt->opt.optlen >> 2;
523 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
526 ip_select_ident_segs(net, skb, sk,
527 skb_shinfo(skb)->gso_segs ?: 1);
529 /* TODO : should we use skb->sk here instead of sk ? */
530 skb->priority = sk->sk_priority;
531 skb->mark = sk->sk_mark;
533 res = ip_local_out(net, sk, skb);
539 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
541 return -EHOSTUNREACH;
543 EXPORT_SYMBOL(__ip_queue_xmit);
545 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
547 return __ip_queue_xmit(sk, skb, fl, inet_sk(sk)->tos);
549 EXPORT_SYMBOL(ip_queue_xmit);
551 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
553 to->pkt_type = from->pkt_type;
554 to->priority = from->priority;
555 to->protocol = from->protocol;
556 to->skb_iif = from->skb_iif;
558 skb_dst_copy(to, from);
560 to->mark = from->mark;
562 skb_copy_hash(to, from);
564 #ifdef CONFIG_NET_SCHED
565 to->tc_index = from->tc_index;
568 skb_ext_copy(to, from);
569 #if IS_ENABLED(CONFIG_IP_VS)
570 to->ipvs_property = from->ipvs_property;
572 skb_copy_secmark(to, from);
575 static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
577 int (*output)(struct net *, struct sock *, struct sk_buff *))
579 struct iphdr *iph = ip_hdr(skb);
581 if ((iph->frag_off & htons(IP_DF)) == 0)
582 return ip_do_fragment(net, sk, skb, output);
584 if (unlikely(!skb->ignore_df ||
585 (IPCB(skb)->frag_max_size &&
586 IPCB(skb)->frag_max_size > mtu))) {
587 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
588 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
594 return ip_do_fragment(net, sk, skb, output);
597 void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
598 unsigned int hlen, struct ip_fraglist_iter *iter)
600 unsigned int first_len = skb_pagelen(skb);
602 iter->frag = skb_shinfo(skb)->frag_list;
603 skb_frag_list_init(skb);
609 skb->data_len = first_len - skb_headlen(skb);
610 skb->len = first_len;
611 iph->tot_len = htons(first_len);
612 iph->frag_off = htons(IP_MF);
615 EXPORT_SYMBOL(ip_fraglist_init);
617 static void ip_fraglist_ipcb_prepare(struct sk_buff *skb,
618 struct ip_fraglist_iter *iter)
620 struct sk_buff *to = iter->frag;
622 /* Copy the flags to each fragment. */
623 IPCB(to)->flags = IPCB(skb)->flags;
625 if (iter->offset == 0)
626 ip_options_fragment(to);
629 void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
631 unsigned int hlen = iter->hlen;
632 struct iphdr *iph = iter->iph;
633 struct sk_buff *frag;
636 frag->ip_summed = CHECKSUM_NONE;
637 skb_reset_transport_header(frag);
638 __skb_push(frag, hlen);
639 skb_reset_network_header(frag);
640 memcpy(skb_network_header(frag), iph, hlen);
641 iter->iph = ip_hdr(frag);
643 iph->tot_len = htons(frag->len);
644 ip_copy_metadata(frag, skb);
645 iter->offset += skb->len - hlen;
646 iph->frag_off = htons(iter->offset >> 3);
648 iph->frag_off |= htons(IP_MF);
649 /* Ready, complete checksum */
652 EXPORT_SYMBOL(ip_fraglist_prepare);
654 void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
655 unsigned int ll_rs, unsigned int mtu, bool DF,
656 struct ip_frag_state *state)
658 struct iphdr *iph = ip_hdr(skb);
662 state->ll_rs = ll_rs;
665 state->left = skb->len - hlen; /* Space per frame */
666 state->ptr = hlen; /* Where to start from */
668 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
669 state->not_last_frag = iph->frag_off & htons(IP_MF);
671 EXPORT_SYMBOL(ip_frag_init);
673 static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
674 bool first_frag, struct ip_frag_state *state)
676 /* Copy the flags to each fragment. */
677 IPCB(to)->flags = IPCB(from)->flags;
679 /* ANK: dirty, but effective trick. Upgrade options only if
680 * the segment to be fragmented was THE FIRST (otherwise,
681 * options are already fixed) and make it ONCE
682 * on the initial skb, so that all the following fragments
683 * will inherit fixed options.
686 ip_options_fragment(from);
689 struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
691 unsigned int len = state->left;
692 struct sk_buff *skb2;
696 /* IF: it doesn't fit, use 'mtu' - the data space left */
697 if (len > state->mtu)
699 /* IF: we are not sending up to and including the packet end
700 then align the next start on an eight byte boundary */
701 if (len < state->left) {
705 /* Allocate buffer */
706 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
708 return ERR_PTR(-ENOMEM);
711 * Set up data on packet
714 ip_copy_metadata(skb2, skb);
715 skb_reserve(skb2, state->ll_rs);
716 skb_put(skb2, len + state->hlen);
717 skb_reset_network_header(skb2);
718 skb2->transport_header = skb2->network_header + state->hlen;
721 * Charge the memory for the fragment to any owner
726 skb_set_owner_w(skb2, skb->sk);
729 * Copy the packet header into the new buffer.
732 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
735 * Copy a block of the IP datagram.
737 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
742 * Fill in the new header fields.
745 iph->frag_off = htons((state->offset >> 3));
747 iph->frag_off |= htons(IP_DF);
750 * Added AC : If we are fragmenting a fragment that's not the
751 * last fragment then keep MF on each bit
753 if (state->left > 0 || state->not_last_frag)
754 iph->frag_off |= htons(IP_MF);
756 state->offset += len;
758 iph->tot_len = htons(len + state->hlen);
764 EXPORT_SYMBOL(ip_frag_next);
767 * This IP datagram is too large to be sent in one piece. Break it up into
768 * smaller pieces (each of size equal to IP header plus
769 * a block of the data of the original IP data part) that will yet fit in a
770 * single device frame, and queue such a frame for sending.
773 int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
774 int (*output)(struct net *, struct sock *, struct sk_buff *))
777 struct sk_buff *skb2;
778 struct rtable *rt = skb_rtable(skb);
779 unsigned int mtu, hlen, ll_rs;
780 struct ip_fraglist_iter iter;
781 ktime_t tstamp = skb->tstamp;
782 struct ip_frag_state state;
785 /* for offloaded checksums cleanup checksum before fragmentation */
786 if (skb->ip_summed == CHECKSUM_PARTIAL &&
787 (err = skb_checksum_help(skb)))
791 * Point into the IP datagram header.
796 mtu = ip_skb_dst_mtu(sk, skb);
797 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
798 mtu = IPCB(skb)->frag_max_size;
801 * Setup starting values.
805 mtu = mtu - hlen; /* Size of data space */
806 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
807 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
809 /* When frag_list is given, use it. First, check its validity:
810 * some transformers could create wrong frag_list or break existing
811 * one, it is not prohibited. In this case fall back to copying.
813 * LATER: this step can be merged to real generation of fragments,
814 * we can switch to copy when see the first bad fragment.
816 if (skb_has_frag_list(skb)) {
817 struct sk_buff *frag, *frag2;
818 unsigned int first_len = skb_pagelen(skb);
820 if (first_len - hlen > mtu ||
821 ((first_len - hlen) & 7) ||
822 ip_is_fragment(iph) ||
824 skb_headroom(skb) < ll_rs)
827 skb_walk_frags(skb, frag) {
828 /* Correct geometry. */
829 if (frag->len > mtu ||
830 ((frag->len & 7) && frag->next) ||
831 skb_headroom(frag) < hlen + ll_rs)
832 goto slow_path_clean;
834 /* Partially cloned skb? */
835 if (skb_shared(frag))
836 goto slow_path_clean;
841 frag->destructor = sock_wfree;
843 skb->truesize -= frag->truesize;
846 /* Everything is OK. Generate! */
847 ip_fraglist_init(skb, iph, hlen, &iter);
850 /* Prepare header of the next frame,
851 * before previous one went down. */
853 ip_fraglist_ipcb_prepare(skb, &iter);
854 ip_fraglist_prepare(skb, &iter);
857 skb->tstamp = tstamp;
858 err = output(net, sk, skb);
861 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
862 if (err || !iter.frag)
865 skb = ip_fraglist_next(&iter);
869 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
873 kfree_skb_list(iter.frag);
875 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
879 skb_walk_frags(skb, frag2) {
883 frag2->destructor = NULL;
884 skb->truesize += frag2->truesize;
890 * Fragment the datagram.
893 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
897 * Keep copying data until we run out.
900 while (state.left > 0) {
901 bool first_frag = (state.offset == 0);
903 skb2 = ip_frag_next(skb, &state);
908 ip_frag_ipcb(skb, skb2, first_frag, &state);
911 * Put this fragment into the sending queue.
913 skb2->tstamp = tstamp;
914 err = output(net, sk, skb2);
918 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
921 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
926 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
929 EXPORT_SYMBOL(ip_do_fragment);
932 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
934 struct msghdr *msg = from;
936 if (skb->ip_summed == CHECKSUM_PARTIAL) {
937 if (!copy_from_iter_full(to, len, &msg->msg_iter))
941 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
943 skb->csum = csum_block_add(skb->csum, csum, odd);
947 EXPORT_SYMBOL(ip_generic_getfrag);
950 csum_page(struct page *page, int offset, int copy)
955 csum = csum_partial(kaddr + offset, copy, 0);
960 static int __ip_append_data(struct sock *sk,
962 struct sk_buff_head *queue,
963 struct inet_cork *cork,
964 struct page_frag *pfrag,
965 int getfrag(void *from, char *to, int offset,
966 int len, int odd, struct sk_buff *skb),
967 void *from, int length, int transhdrlen,
970 struct inet_sock *inet = inet_sk(sk);
971 struct ubuf_info *uarg = NULL;
974 struct ip_options *opt = cork->opt;
981 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
982 int csummode = CHECKSUM_NONE;
983 struct rtable *rt = (struct rtable *)cork->dst;
984 unsigned int wmem_alloc_delta = 0;
985 bool paged, extra_uref = false;
988 skb = skb_peek_tail(queue);
990 exthdrlen = !skb ? rt->dst.header_len : 0;
991 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
992 paged = !!cork->gso_size;
994 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
995 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
996 tskey = sk->sk_tskey++;
998 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1000 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1001 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1002 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu;
1004 if (cork->length + length > maxnonfragsize - fragheaderlen) {
1005 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1006 mtu - (opt ? opt->optlen : 0));
1011 * transhdrlen > 0 means that this is the first fragment and we wish
1012 * it won't be fragmented in the future.
1015 length + fragheaderlen <= mtu &&
1016 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
1017 (!(flags & MSG_MORE) || cork->gso_size) &&
1018 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
1019 csummode = CHECKSUM_PARTIAL;
1021 if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) {
1022 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
1025 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
1026 if (rt->dst.dev->features & NETIF_F_SG &&
1027 csummode == CHECKSUM_PARTIAL) {
1031 skb_zcopy_set(skb, uarg, &extra_uref);
1035 cork->length += length;
1037 /* So, what's going on in the loop below?
1039 * We use calculated fragment length to generate chained skb,
1040 * each of segments is IP fragment ready for sending to network after
1041 * adding appropriate IP header.
1047 while (length > 0) {
1048 /* Check if the remaining data fits into current packet. */
1049 copy = mtu - skb->len;
1051 copy = maxfraglen - skb->len;
1054 unsigned int datalen;
1055 unsigned int fraglen;
1056 unsigned int fraggap;
1057 unsigned int alloclen;
1058 unsigned int pagedlen;
1059 struct sk_buff *skb_prev;
1063 fraggap = skb_prev->len - maxfraglen;
1068 * If remaining data exceeds the mtu,
1069 * we know we need more fragment(s).
1071 datalen = length + fraggap;
1072 if (datalen > mtu - fragheaderlen)
1073 datalen = maxfraglen - fragheaderlen;
1074 fraglen = datalen + fragheaderlen;
1077 if ((flags & MSG_MORE) &&
1078 !(rt->dst.dev->features&NETIF_F_SG))
1083 alloclen = min_t(int, fraglen, MAX_HEADER);
1084 pagedlen = fraglen - alloclen;
1087 alloclen += exthdrlen;
1089 /* The last fragment gets additional space at tail.
1090 * Note, with MSG_MORE we overallocate on fragments,
1091 * because we have no idea what fragment will be
1094 if (datalen == length + fraggap)
1095 alloclen += rt->dst.trailer_len;
1098 skb = sock_alloc_send_skb(sk,
1099 alloclen + hh_len + 15,
1100 (flags & MSG_DONTWAIT), &err);
1103 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1105 skb = alloc_skb(alloclen + hh_len + 15,
1114 * Fill in the control structures
1116 skb->ip_summed = csummode;
1118 skb_reserve(skb, hh_len);
1121 * Find where to start putting bytes.
1123 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1124 skb_set_network_header(skb, exthdrlen);
1125 skb->transport_header = (skb->network_header +
1127 data += fragheaderlen + exthdrlen;
1130 skb->csum = skb_copy_and_csum_bits(
1131 skb_prev, maxfraglen,
1132 data + transhdrlen, fraggap);
1133 skb_prev->csum = csum_sub(skb_prev->csum,
1136 pskb_trim_unique(skb_prev, maxfraglen);
1139 copy = datalen - transhdrlen - fraggap - pagedlen;
1140 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1147 length -= copy + transhdrlen;
1150 csummode = CHECKSUM_NONE;
1152 /* only the initial fragment is time stamped */
1153 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1155 skb_shinfo(skb)->tskey = tskey;
1157 skb_zcopy_set(skb, uarg, &extra_uref);
1159 if ((flags & MSG_CONFIRM) && !skb_prev)
1160 skb_set_dst_pending_confirm(skb, 1);
1163 * Put the packet on the pending queue.
1165 if (!skb->destructor) {
1166 skb->destructor = sock_wfree;
1168 wmem_alloc_delta += skb->truesize;
1170 __skb_queue_tail(queue, skb);
1177 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1178 skb_tailroom(skb) >= copy) {
1182 if (getfrag(from, skb_put(skb, copy),
1183 offset, copy, off, skb) < 0) {
1184 __skb_trim(skb, off);
1188 } else if (!uarg || !uarg->zerocopy) {
1189 int i = skb_shinfo(skb)->nr_frags;
1192 if (!sk_page_frag_refill(sk, pfrag))
1195 if (!skb_can_coalesce(skb, i, pfrag->page,
1198 if (i == MAX_SKB_FRAGS)
1201 __skb_fill_page_desc(skb, i, pfrag->page,
1203 skb_shinfo(skb)->nr_frags = ++i;
1204 get_page(pfrag->page);
1206 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1208 page_address(pfrag->page) + pfrag->offset,
1209 offset, copy, skb->len, skb) < 0)
1212 pfrag->offset += copy;
1213 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1215 skb->data_len += copy;
1216 skb->truesize += copy;
1217 wmem_alloc_delta += copy;
1219 err = skb_zerocopy_iter_dgram(skb, from, copy);
1227 if (wmem_alloc_delta)
1228 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1234 net_zcopy_put_abort(uarg, extra_uref);
1235 cork->length -= length;
1236 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1237 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1241 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1242 struct ipcm_cookie *ipc, struct rtable **rtp)
1244 struct ip_options_rcu *opt;
1252 * setup for corking.
1257 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1259 if (unlikely(!cork->opt))
1262 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1263 cork->flags |= IPCORK_OPT;
1264 cork->addr = ipc->addr;
1267 cork->fragsize = ip_sk_use_pmtu(sk) ?
1268 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
1270 if (!inetdev_valid_mtu(cork->fragsize))
1271 return -ENETUNREACH;
1273 cork->gso_size = ipc->gso_size;
1275 cork->dst = &rt->dst;
1276 /* We stole this route, caller should not release it. */
1280 cork->ttl = ipc->ttl;
1281 cork->tos = ipc->tos;
1282 cork->mark = ipc->sockc.mark;
1283 cork->priority = ipc->priority;
1284 cork->transmit_time = ipc->sockc.transmit_time;
1286 sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags);
1292 * ip_append_data() and ip_append_page() can make one large IP datagram
1293 * from many pieces of data. Each pieces will be holded on the socket
1294 * until ip_push_pending_frames() is called. Each piece can be a page
1297 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1298 * this interface potentially.
1300 * LATER: length must be adjusted by pad at tail, when it is required.
1302 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1303 int getfrag(void *from, char *to, int offset, int len,
1304 int odd, struct sk_buff *skb),
1305 void *from, int length, int transhdrlen,
1306 struct ipcm_cookie *ipc, struct rtable **rtp,
1309 struct inet_sock *inet = inet_sk(sk);
1312 if (flags&MSG_PROBE)
1315 if (skb_queue_empty(&sk->sk_write_queue)) {
1316 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1323 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1324 sk_page_frag(sk), getfrag,
1325 from, length, transhdrlen, flags);
1328 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1329 int offset, size_t size, int flags)
1331 struct inet_sock *inet = inet_sk(sk);
1332 struct sk_buff *skb;
1334 struct ip_options *opt = NULL;
1335 struct inet_cork *cork;
1340 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1345 if (flags&MSG_PROBE)
1348 if (skb_queue_empty(&sk->sk_write_queue))
1351 cork = &inet->cork.base;
1352 rt = (struct rtable *)cork->dst;
1353 if (cork->flags & IPCORK_OPT)
1356 if (!(rt->dst.dev->features & NETIF_F_SG))
1359 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1360 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
1362 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1363 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1364 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1366 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1367 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1368 mtu - (opt ? opt->optlen : 0));
1372 skb = skb_peek_tail(&sk->sk_write_queue);
1376 cork->length += size;
1379 /* Check if the remaining data fits into current packet. */
1380 len = mtu - skb->len;
1382 len = maxfraglen - skb->len;
1385 struct sk_buff *skb_prev;
1389 fraggap = skb_prev->len - maxfraglen;
1391 alloclen = fragheaderlen + hh_len + fraggap + 15;
1392 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1393 if (unlikely(!skb)) {
1399 * Fill in the control structures
1401 skb->ip_summed = CHECKSUM_NONE;
1403 skb_reserve(skb, hh_len);
1406 * Find where to start putting bytes.
1408 skb_put(skb, fragheaderlen + fraggap);
1409 skb_reset_network_header(skb);
1410 skb->transport_header = (skb->network_header +
1413 skb->csum = skb_copy_and_csum_bits(skb_prev,
1415 skb_transport_header(skb),
1417 skb_prev->csum = csum_sub(skb_prev->csum,
1419 pskb_trim_unique(skb_prev, maxfraglen);
1423 * Put the packet on the pending queue.
1425 __skb_queue_tail(&sk->sk_write_queue, skb);
1432 if (skb_append_pagefrags(skb, page, offset, len)) {
1437 if (skb->ip_summed == CHECKSUM_NONE) {
1439 csum = csum_page(page, offset, len);
1440 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1444 skb->data_len += len;
1445 skb->truesize += len;
1446 refcount_add(len, &sk->sk_wmem_alloc);
1453 cork->length -= size;
1454 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1458 static void ip_cork_release(struct inet_cork *cork)
1460 cork->flags &= ~IPCORK_OPT;
1463 dst_release(cork->dst);
1468 * Combined all pending IP fragments on the socket as one IP datagram
1469 * and push them out.
1471 struct sk_buff *__ip_make_skb(struct sock *sk,
1473 struct sk_buff_head *queue,
1474 struct inet_cork *cork)
1476 struct sk_buff *skb, *tmp_skb;
1477 struct sk_buff **tail_skb;
1478 struct inet_sock *inet = inet_sk(sk);
1479 struct net *net = sock_net(sk);
1480 struct ip_options *opt = NULL;
1481 struct rtable *rt = (struct rtable *)cork->dst;
1486 skb = __skb_dequeue(queue);
1489 tail_skb = &(skb_shinfo(skb)->frag_list);
1491 /* move skb->data to ip header from ext header */
1492 if (skb->data < skb_network_header(skb))
1493 __skb_pull(skb, skb_network_offset(skb));
1494 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1495 __skb_pull(tmp_skb, skb_network_header_len(skb));
1496 *tail_skb = tmp_skb;
1497 tail_skb = &(tmp_skb->next);
1498 skb->len += tmp_skb->len;
1499 skb->data_len += tmp_skb->len;
1500 skb->truesize += tmp_skb->truesize;
1501 tmp_skb->destructor = NULL;
1505 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1506 * to fragment the frame generated here. No matter, what transforms
1507 * how transforms change size of the packet, it will come out.
1509 skb->ignore_df = ip_sk_ignore_df(sk);
1511 /* DF bit is set when we want to see DF on outgoing frames.
1512 * If ignore_df is set too, we still allow to fragment this frame
1514 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1515 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1516 (skb->len <= dst_mtu(&rt->dst) &&
1517 ip_dont_fragment(sk, &rt->dst)))
1520 if (cork->flags & IPCORK_OPT)
1525 else if (rt->rt_type == RTN_MULTICAST)
1528 ttl = ip_select_ttl(inet, &rt->dst);
1533 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1536 iph->protocol = sk->sk_protocol;
1537 ip_copy_addrs(iph, fl4);
1538 ip_select_ident(net, skb, sk);
1541 iph->ihl += opt->optlen >> 2;
1542 ip_options_build(skb, opt, cork->addr, rt, 0);
1545 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1546 skb->mark = cork->mark;
1547 skb->tstamp = cork->transmit_time;
1549 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1553 skb_dst_set(skb, &rt->dst);
1555 if (iph->protocol == IPPROTO_ICMP)
1556 icmp_out_count(net, ((struct icmphdr *)
1557 skb_transport_header(skb))->type);
1559 ip_cork_release(cork);
1564 int ip_send_skb(struct net *net, struct sk_buff *skb)
1568 err = ip_local_out(net, skb->sk, skb);
1571 err = net_xmit_errno(err);
1573 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1579 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1581 struct sk_buff *skb;
1583 skb = ip_finish_skb(sk, fl4);
1587 /* Netfilter gets whole the not fragmented skb. */
1588 return ip_send_skb(sock_net(sk), skb);
1592 * Throw away all pending data on the socket.
1594 static void __ip_flush_pending_frames(struct sock *sk,
1595 struct sk_buff_head *queue,
1596 struct inet_cork *cork)
1598 struct sk_buff *skb;
1600 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1603 ip_cork_release(cork);
1606 void ip_flush_pending_frames(struct sock *sk)
1608 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1611 struct sk_buff *ip_make_skb(struct sock *sk,
1613 int getfrag(void *from, char *to, int offset,
1614 int len, int odd, struct sk_buff *skb),
1615 void *from, int length, int transhdrlen,
1616 struct ipcm_cookie *ipc, struct rtable **rtp,
1617 struct inet_cork *cork, unsigned int flags)
1619 struct sk_buff_head queue;
1622 if (flags & MSG_PROBE)
1625 __skb_queue_head_init(&queue);
1630 err = ip_setup_cork(sk, cork, ipc, rtp);
1632 return ERR_PTR(err);
1634 err = __ip_append_data(sk, fl4, &queue, cork,
1635 ¤t->task_frag, getfrag,
1636 from, length, transhdrlen, flags);
1638 __ip_flush_pending_frames(sk, &queue, cork);
1639 return ERR_PTR(err);
1642 return __ip_make_skb(sk, fl4, &queue, cork);
1646 * Fetch data from kernel space and fill in checksum if needed.
1648 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1649 int len, int odd, struct sk_buff *skb)
1653 csum = csum_partial_copy_nocheck(dptr+offset, to, len);
1654 skb->csum = csum_block_add(skb->csum, csum, odd);
1659 * Generic function to send a packet as reply to another packet.
1660 * Used to send some TCP resets/acks so far.
1662 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1663 const struct ip_options *sopt,
1664 __be32 daddr, __be32 saddr,
1665 const struct ip_reply_arg *arg,
1666 unsigned int len, u64 transmit_time)
1668 struct ip_options_data replyopts;
1669 struct ipcm_cookie ipc;
1671 struct rtable *rt = skb_rtable(skb);
1672 struct net *net = sock_net(sk);
1673 struct sk_buff *nskb;
1677 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1682 ipc.sockc.transmit_time = transmit_time;
1684 if (replyopts.opt.opt.optlen) {
1685 ipc.opt = &replyopts.opt;
1687 if (replyopts.opt.opt.srr)
1688 daddr = replyopts.opt.opt.faddr;
1691 oif = arg->bound_dev_if;
1692 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1695 flowi4_init_output(&fl4, oif,
1696 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1698 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1699 ip_reply_arg_flowi_flags(arg),
1701 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1703 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
1704 rt = ip_route_output_key(net, &fl4);
1708 inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK;
1710 sk->sk_protocol = ip_hdr(skb)->protocol;
1711 sk->sk_bound_dev_if = arg->bound_dev_if;
1712 sk->sk_sndbuf = sysctl_wmem_default;
1713 ipc.sockc.mark = fl4.flowi4_mark;
1714 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1715 len, 0, &ipc, &rt, MSG_DONTWAIT);
1716 if (unlikely(err)) {
1717 ip_flush_pending_frames(sk);
1721 nskb = skb_peek(&sk->sk_write_queue);
1723 if (arg->csumoffset >= 0)
1724 *((__sum16 *)skb_transport_header(nskb) +
1725 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1727 nskb->ip_summed = CHECKSUM_NONE;
1728 ip_push_pending_frames(sk, &fl4);
1734 void __init ip_init(void)
1739 #if defined(CONFIG_IP_MULTICAST)