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