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 readibility. 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/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> 85 86static int 87ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 88 unsigned int mtu, 89 int (*output)(struct net *, struct sock *, struct sk_buff *)); 90 91/* Generate a checksum for an outgoing IP datagram. */ 92void ip_send_check(struct iphdr *iph) 93{ 94 iph->check = 0; 95 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 96} 97EXPORT_SYMBOL(ip_send_check); 98 99int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb) 100{ 101 struct iphdr *iph = ip_hdr(skb); 102 103 iph->tot_len = htons(skb->len); 104 ip_send_check(iph); 105 106 /* if egress device is enslaved to an L3 master device pass the 107 * skb to its handler for processing 108 */ 109 skb = l3mdev_ip_out(sk, skb); 110 if (unlikely(!skb)) 111 return 0; 112 113 skb->protocol = htons(ETH_P_IP); 114 115 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, 116 net, sk, skb, NULL, skb_dst(skb)->dev, 117 dst_output); 118} 119 120int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb) 121{ 122 int err; 123 124 err = __ip_local_out(net, sk, skb); 125 if (likely(err == 1)) 126 err = dst_output(net, sk, skb); 127 128 return err; 129} 130EXPORT_SYMBOL_GPL(ip_local_out); 131 132static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 133{ 134 int ttl = inet->uc_ttl; 135 136 if (ttl < 0) 137 ttl = ip4_dst_hoplimit(dst); 138 return ttl; 139} 140 141/* 142 * Add an ip header to a skbuff and send it out. 143 * 144 */ 145int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk, 146 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt, 147 u8 tos) 148{ 149 struct inet_sock *inet = inet_sk(sk); 150 struct rtable *rt = skb_rtable(skb); 151 struct net *net = sock_net(sk); 152 struct iphdr *iph; 153 154 /* Build the IP header. */ 155 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 156 skb_reset_network_header(skb); 157 iph = ip_hdr(skb); 158 iph->version = 4; 159 iph->ihl = 5; 160 iph->tos = tos; 161 iph->ttl = ip_select_ttl(inet, &rt->dst); 162 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr); 163 iph->saddr = saddr; 164 iph->protocol = sk->sk_protocol; 165 /* Do not bother generating IPID for small packets (eg SYNACK) */ 166 if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) { 167 iph->frag_off = htons(IP_DF); 168 iph->id = 0; 169 } else { 170 iph->frag_off = 0; 171 /* TCP packets here are SYNACK with fat IPv4/TCP options. 172 * Avoid using the hashed IP ident generator. 173 */ 174 if (sk->sk_protocol == IPPROTO_TCP) 175 iph->id = (__force __be16)prandom_u32(); 176 else 177 __ip_select_ident(net, iph, 1); 178 } 179 180 if (opt && opt->opt.optlen) { 181 iph->ihl += opt->opt.optlen>>2; 182 ip_options_build(skb, &opt->opt, daddr, rt, 0); 183 } 184 185 skb->priority = sk->sk_priority; 186 if (!skb->mark) 187 skb->mark = sk->sk_mark; 188 189 /* Send it out. */ 190 return ip_local_out(net, skb->sk, skb); 191} 192EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 193 194static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb) 195{ 196 struct dst_entry *dst = skb_dst(skb); 197 struct rtable *rt = (struct rtable *)dst; 198 struct net_device *dev = dst->dev; 199 unsigned int hh_len = LL_RESERVED_SPACE(dev); 200 struct neighbour *neigh; 201 bool is_v6gw = false; 202 203 if (rt->rt_type == RTN_MULTICAST) { 204 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len); 205 } else if (rt->rt_type == RTN_BROADCAST) 206 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len); 207 208 /* Be paranoid, rather than too clever. */ 209 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 210 struct sk_buff *skb2; 211 212 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 213 if (!skb2) { 214 kfree_skb(skb); 215 return -ENOMEM; 216 } 217 if (skb->sk) 218 skb_set_owner_w(skb2, skb->sk); 219 consume_skb(skb); 220 skb = skb2; 221 } 222 223 if (lwtunnel_xmit_redirect(dst->lwtstate)) { 224 int res = lwtunnel_xmit(skb); 225 226 if (res != LWTUNNEL_XMIT_CONTINUE) 227 return res; 228 } 229 230 rcu_read_lock_bh(); 231 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw); 232 if (!IS_ERR(neigh)) { 233 int res; 234 235 sock_confirm_neigh(skb, neigh); 236 /* if crossing protocols, can not use the cached header */ 237 res = neigh_output(neigh, skb, is_v6gw); 238 rcu_read_unlock_bh(); 239 return res; 240 } 241 rcu_read_unlock_bh(); 242 243 net_dbg_ratelimited("%s: No header cache and no neighbour!\n", 244 __func__); 245 kfree_skb(skb); 246 return -EINVAL; 247} 248 249static int ip_finish_output_gso(struct net *net, struct sock *sk, 250 struct sk_buff *skb, unsigned int mtu) 251{ 252 struct sk_buff *segs, *nskb; 253 netdev_features_t features; 254 int ret = 0; 255 256 /* common case: seglen is <= mtu 257 */ 258 if (skb_gso_validate_network_len(skb, mtu)) 259 return ip_finish_output2(net, sk, skb); 260 261 /* Slowpath - GSO segment length exceeds the egress MTU. 262 * 263 * This can happen in several cases: 264 * - Forwarding of a TCP GRO skb, when DF flag is not set. 265 * - Forwarding of an skb that arrived on a virtualization interface 266 * (virtio-net/vhost/tap) with TSO/GSO size set by other network 267 * stack. 268 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an 269 * interface with a smaller MTU. 270 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is 271 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an 272 * insufficent MTU. 273 */ 274 features = netif_skb_features(skb); 275 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET); 276 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 277 if (IS_ERR_OR_NULL(segs)) { 278 kfree_skb(skb); 279 return -ENOMEM; 280 } 281 282 consume_skb(skb); 283 284 skb_list_walk_safe(segs, segs, nskb) { 285 int err; 286 287 skb_mark_not_on_list(segs); 288 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2); 289 290 if (err && ret == 0) 291 ret = err; 292 } 293 294 return ret; 295} 296 297static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb) 298{ 299 unsigned int mtu; 300 301#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 302 /* Policy lookup after SNAT yielded a new policy */ 303 if (skb_dst(skb)->xfrm) { 304 IPCB(skb)->flags |= IPSKB_REROUTED; 305 return dst_output(net, sk, skb); 306 } 307#endif 308 mtu = ip_skb_dst_mtu(sk, skb); 309 if (skb_is_gso(skb)) 310 return ip_finish_output_gso(net, sk, skb, mtu); 311 312 if (skb->len > mtu || IPCB(skb)->frag_max_size) 313 return ip_fragment(net, sk, skb, mtu, ip_finish_output2); 314 315 return ip_finish_output2(net, sk, skb); 316} 317 318static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb) 319{ 320 int ret; 321 322 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb); 323 switch (ret) { 324 case NET_XMIT_SUCCESS: 325 return __ip_finish_output(net, sk, skb); 326 case NET_XMIT_CN: 327 return __ip_finish_output(net, sk, skb) ? : ret; 328 default: 329 kfree_skb(skb); 330 return ret; 331 } 332} 333 334static int ip_mc_finish_output(struct net *net, struct sock *sk, 335 struct sk_buff *skb) 336{ 337 struct rtable *new_rt; 338 bool do_cn = false; 339 int ret, err; 340 341 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb); 342 switch (ret) { 343 case NET_XMIT_CN: 344 do_cn = true; 345 fallthrough; 346 case NET_XMIT_SUCCESS: 347 break; 348 default: 349 kfree_skb(skb); 350 return ret; 351 } 352 353 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting 354 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten, 355 * see ipv4_pktinfo_prepare(). 356 */ 357 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb)); 358 if (new_rt) { 359 new_rt->rt_iif = 0; 360 skb_dst_drop(skb); 361 skb_dst_set(skb, &new_rt->dst); 362 } 363 364 err = dev_loopback_xmit(net, sk, skb); 365 return (do_cn && err) ? ret : err; 366} 367 368int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb) 369{ 370 struct rtable *rt = skb_rtable(skb); 371 struct net_device *dev = rt->dst.dev; 372 373 /* 374 * If the indicated interface is up and running, send the packet. 375 */ 376 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len); 377 378 skb->dev = dev; 379 skb->protocol = htons(ETH_P_IP); 380 381 /* 382 * Multicasts are looped back for other local users 383 */ 384 385 if (rt->rt_flags&RTCF_MULTICAST) { 386 if (sk_mc_loop(sk) 387#ifdef CONFIG_IP_MROUTE 388 /* Small optimization: do not loopback not local frames, 389 which returned after forwarding; they will be dropped 390 by ip_mr_input in any case. 391 Note, that local frames are looped back to be delivered 392 to local recipients. 393 394 This check is duplicated in ip_mr_input at the moment. 395 */ 396 && 397 ((rt->rt_flags & RTCF_LOCAL) || 398 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 399#endif 400 ) { 401 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 402 if (newskb) 403 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 404 net, sk, newskb, NULL, newskb->dev, 405 ip_mc_finish_output); 406 } 407 408 /* Multicasts with ttl 0 must not go beyond the host */ 409 410 if (ip_hdr(skb)->ttl == 0) { 411 kfree_skb(skb); 412 return 0; 413 } 414 } 415 416 if (rt->rt_flags&RTCF_BROADCAST) { 417 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 418 if (newskb) 419 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 420 net, sk, newskb, NULL, newskb->dev, 421 ip_mc_finish_output); 422 } 423 424 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, 425 net, sk, skb, NULL, skb->dev, 426 ip_finish_output, 427 !(IPCB(skb)->flags & IPSKB_REROUTED)); 428} 429 430int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb) 431{ 432 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev; 433 434 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len); 435 436 skb->dev = dev; 437 skb->protocol = htons(ETH_P_IP); 438 439 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, 440 net, sk, skb, indev, dev, 441 ip_finish_output, 442 !(IPCB(skb)->flags & IPSKB_REROUTED)); 443} 444 445/* 446 * copy saddr and daddr, possibly using 64bit load/stores 447 * Equivalent to : 448 * iph->saddr = fl4->saddr; 449 * iph->daddr = fl4->daddr; 450 */ 451static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 452{ 453 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 454 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 455 456 iph->saddr = fl4->saddr; 457 iph->daddr = fl4->daddr; 458} 459 460/* Note: skb->sk can be different from sk, in case of tunnels */ 461int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl, 462 __u8 tos) 463{ 464 struct inet_sock *inet = inet_sk(sk); 465 struct net *net = sock_net(sk); 466 struct ip_options_rcu *inet_opt; 467 struct flowi4 *fl4; 468 struct rtable *rt; 469 struct iphdr *iph; 470 int res; 471 472 /* Skip all of this if the packet is already routed, 473 * f.e. by something like SCTP. 474 */ 475 rcu_read_lock(); 476 inet_opt = rcu_dereference(inet->inet_opt); 477 fl4 = &fl->u.ip4; 478 rt = skb_rtable(skb); 479 if (rt) 480 goto packet_routed; 481 482 /* Make sure we can route this packet. */ 483 rt = (struct rtable *)__sk_dst_check(sk, 0); 484 if (!rt) { 485 __be32 daddr; 486 487 /* Use correct destination address if we have options. */ 488 daddr = inet->inet_daddr; 489 if (inet_opt && inet_opt->opt.srr) 490 daddr = inet_opt->opt.faddr; 491 492 /* If this fails, retransmit mechanism of transport layer will 493 * keep trying until route appears or the connection times 494 * itself out. 495 */ 496 rt = ip_route_output_ports(net, fl4, sk, 497 daddr, inet->inet_saddr, 498 inet->inet_dport, 499 inet->inet_sport, 500 sk->sk_protocol, 501 RT_CONN_FLAGS_TOS(sk, tos), 502 sk->sk_bound_dev_if); 503 if (IS_ERR(rt)) 504 goto no_route; 505 sk_setup_caps(sk, &rt->dst); 506 } 507 skb_dst_set_noref(skb, &rt->dst); 508 509packet_routed: 510 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) 511 goto no_route; 512 513 /* OK, we know where to send it, allocate and build IP header. */ 514 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 515 skb_reset_network_header(skb); 516 iph = ip_hdr(skb); 517 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff)); 518 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df) 519 iph->frag_off = htons(IP_DF); 520 else 521 iph->frag_off = 0; 522 iph->ttl = ip_select_ttl(inet, &rt->dst); 523 iph->protocol = sk->sk_protocol; 524 ip_copy_addrs(iph, fl4); 525 526 /* Transport layer set skb->h.foo itself. */ 527 528 if (inet_opt && inet_opt->opt.optlen) { 529 iph->ihl += inet_opt->opt.optlen >> 2; 530 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 531 } 532 533 ip_select_ident_segs(net, skb, sk, 534 skb_shinfo(skb)->gso_segs ?: 1); 535 536 /* TODO : should we use skb->sk here instead of sk ? */ 537 skb->priority = sk->sk_priority; 538 skb->mark = sk->sk_mark; 539 540 res = ip_local_out(net, sk, skb); 541 rcu_read_unlock(); 542 return res; 543 544no_route: 545 rcu_read_unlock(); 546 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 547 kfree_skb(skb); 548 return -EHOSTUNREACH; 549} 550EXPORT_SYMBOL(__ip_queue_xmit); 551 552int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl) 553{ 554 return __ip_queue_xmit(sk, skb, fl, inet_sk(sk)->tos); 555} 556EXPORT_SYMBOL(ip_queue_xmit); 557 558static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 559{ 560 to->pkt_type = from->pkt_type; 561 to->priority = from->priority; 562 to->protocol = from->protocol; 563 to->skb_iif = from->skb_iif; 564 skb_dst_drop(to); 565 skb_dst_copy(to, from); 566 to->dev = from->dev; 567 to->mark = from->mark; 568 569 skb_copy_hash(to, from); 570 571#ifdef CONFIG_NET_SCHED 572 to->tc_index = from->tc_index; 573#endif 574 nf_copy(to, from); 575 skb_ext_copy(to, from); 576#if IS_ENABLED(CONFIG_IP_VS) 577 to->ipvs_property = from->ipvs_property; 578#endif 579 skb_copy_secmark(to, from); 580} 581 582static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 583 unsigned int mtu, 584 int (*output)(struct net *, struct sock *, struct sk_buff *)) 585{ 586 struct iphdr *iph = ip_hdr(skb); 587 588 if ((iph->frag_off & htons(IP_DF)) == 0) 589 return ip_do_fragment(net, sk, skb, output); 590 591 if (unlikely(!skb->ignore_df || 592 (IPCB(skb)->frag_max_size && 593 IPCB(skb)->frag_max_size > mtu))) { 594 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 595 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 596 htonl(mtu)); 597 kfree_skb(skb); 598 return -EMSGSIZE; 599 } 600 601 return ip_do_fragment(net, sk, skb, output); 602} 603 604void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph, 605 unsigned int hlen, struct ip_fraglist_iter *iter) 606{ 607 unsigned int first_len = skb_pagelen(skb); 608 609 iter->frag = skb_shinfo(skb)->frag_list; 610 skb_frag_list_init(skb); 611 612 iter->offset = 0; 613 iter->iph = iph; 614 iter->hlen = hlen; 615 616 skb->data_len = first_len - skb_headlen(skb); 617 skb->len = first_len; 618 iph->tot_len = htons(first_len); 619 iph->frag_off = htons(IP_MF); 620 ip_send_check(iph); 621} 622EXPORT_SYMBOL(ip_fraglist_init); 623 624void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter) 625{ 626 unsigned int hlen = iter->hlen; 627 struct iphdr *iph = iter->iph; 628 struct sk_buff *frag; 629 630 frag = iter->frag; 631 frag->ip_summed = CHECKSUM_NONE; 632 skb_reset_transport_header(frag); 633 __skb_push(frag, hlen); 634 skb_reset_network_header(frag); 635 memcpy(skb_network_header(frag), iph, hlen); 636 iter->iph = ip_hdr(frag); 637 iph = iter->iph; 638 iph->tot_len = htons(frag->len); 639 ip_copy_metadata(frag, skb); 640 iter->offset += skb->len - hlen; 641 iph->frag_off = htons(iter->offset >> 3); 642 if (frag->next) 643 iph->frag_off |= htons(IP_MF); 644 /* Ready, complete checksum */ 645 ip_send_check(iph); 646} 647EXPORT_SYMBOL(ip_fraglist_prepare); 648 649void ip_frag_init(struct sk_buff *skb, unsigned int hlen, 650 unsigned int ll_rs, unsigned int mtu, bool DF, 651 struct ip_frag_state *state) 652{ 653 struct iphdr *iph = ip_hdr(skb); 654 655 state->DF = DF; 656 state->hlen = hlen; 657 state->ll_rs = ll_rs; 658 state->mtu = mtu; 659 660 state->left = skb->len - hlen; /* Space per frame */ 661 state->ptr = hlen; /* Where to start from */ 662 663 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 664 state->not_last_frag = iph->frag_off & htons(IP_MF); 665} 666EXPORT_SYMBOL(ip_frag_init); 667 668static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to, 669 bool first_frag) 670{ 671 /* Copy the flags to each fragment. */ 672 IPCB(to)->flags = IPCB(from)->flags; 673 674 /* ANK: dirty, but effective trick. Upgrade options only if 675 * the segment to be fragmented was THE FIRST (otherwise, 676 * options are already fixed) and make it ONCE 677 * on the initial skb, so that all the following fragments 678 * will inherit fixed options. 679 */ 680 if (first_frag) 681 ip_options_fragment(from); 682} 683 684struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state) 685{ 686 unsigned int len = state->left; 687 struct sk_buff *skb2; 688 struct iphdr *iph; 689 690 len = state->left; 691 /* IF: it doesn't fit, use 'mtu' - the data space left */ 692 if (len > state->mtu) 693 len = state->mtu; 694 /* IF: we are not sending up to and including the packet end 695 then align the next start on an eight byte boundary */ 696 if (len < state->left) { 697 len &= ~7; 698 } 699 700 /* Allocate buffer */ 701 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC); 702 if (!skb2) 703 return ERR_PTR(-ENOMEM); 704 705 /* 706 * Set up data on packet 707 */ 708 709 ip_copy_metadata(skb2, skb); 710 skb_reserve(skb2, state->ll_rs); 711 skb_put(skb2, len + state->hlen); 712 skb_reset_network_header(skb2); 713 skb2->transport_header = skb2->network_header + state->hlen; 714 715 /* 716 * Charge the memory for the fragment to any owner 717 * it might possess 718 */ 719 720 if (skb->sk) 721 skb_set_owner_w(skb2, skb->sk); 722 723 /* 724 * Copy the packet header into the new buffer. 725 */ 726 727 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen); 728 729 /* 730 * Copy a block of the IP datagram. 731 */ 732 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len)) 733 BUG(); 734 state->left -= len; 735 736 /* 737 * Fill in the new header fields. 738 */ 739 iph = ip_hdr(skb2); 740 iph->frag_off = htons((state->offset >> 3)); 741 if (state->DF) 742 iph->frag_off |= htons(IP_DF); 743 744 /* 745 * Added AC : If we are fragmenting a fragment that's not the 746 * last fragment then keep MF on each bit 747 */ 748 if (state->left > 0 || state->not_last_frag) 749 iph->frag_off |= htons(IP_MF); 750 state->ptr += len; 751 state->offset += len; 752 753 iph->tot_len = htons(len + state->hlen); 754 755 ip_send_check(iph); 756 757 return skb2; 758} 759EXPORT_SYMBOL(ip_frag_next); 760 761/* 762 * This IP datagram is too large to be sent in one piece. Break it up into 763 * smaller pieces (each of size equal to IP header plus 764 * a block of the data of the original IP data part) that will yet fit in a 765 * single device frame, and queue such a frame for sending. 766 */ 767 768int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 769 int (*output)(struct net *, struct sock *, struct sk_buff *)) 770{ 771 struct iphdr *iph; 772 struct sk_buff *skb2; 773 struct rtable *rt = skb_rtable(skb); 774 unsigned int mtu, hlen, ll_rs; 775 struct ip_fraglist_iter iter; 776 ktime_t tstamp = skb->tstamp; 777 struct ip_frag_state state; 778 int err = 0; 779 780 /* for offloaded checksums cleanup checksum before fragmentation */ 781 if (skb->ip_summed == CHECKSUM_PARTIAL && 782 (err = skb_checksum_help(skb))) 783 goto fail; 784 785 /* 786 * Point into the IP datagram header. 787 */ 788 789 iph = ip_hdr(skb); 790 791 mtu = ip_skb_dst_mtu(sk, skb); 792 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu) 793 mtu = IPCB(skb)->frag_max_size; 794 795 /* 796 * Setup starting values. 797 */ 798 799 hlen = iph->ihl * 4; 800 mtu = mtu - hlen; /* Size of data space */ 801 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 802 ll_rs = LL_RESERVED_SPACE(rt->dst.dev); 803 804 /* When frag_list is given, use it. First, check its validity: 805 * some transformers could create wrong frag_list or break existing 806 * one, it is not prohibited. In this case fall back to copying. 807 * 808 * LATER: this step can be merged to real generation of fragments, 809 * we can switch to copy when see the first bad fragment. 810 */ 811 if (skb_has_frag_list(skb)) { 812 struct sk_buff *frag, *frag2; 813 unsigned int first_len = skb_pagelen(skb); 814 815 if (first_len - hlen > mtu || 816 ((first_len - hlen) & 7) || 817 ip_is_fragment(iph) || 818 skb_cloned(skb) || 819 skb_headroom(skb) < ll_rs) 820 goto slow_path; 821 822 skb_walk_frags(skb, frag) { 823 /* Correct geometry. */ 824 if (frag->len > mtu || 825 ((frag->len & 7) && frag->next) || 826 skb_headroom(frag) < hlen + ll_rs) 827 goto slow_path_clean; 828 829 /* Partially cloned skb? */ 830 if (skb_shared(frag)) 831 goto slow_path_clean; 832 833 BUG_ON(frag->sk); 834 if (skb->sk) { 835 frag->sk = skb->sk; 836 frag->destructor = sock_wfree; 837 } 838 skb->truesize -= frag->truesize; 839 } 840 841 /* Everything is OK. Generate! */ 842 ip_fraglist_init(skb, iph, hlen, &iter); 843 844 for (;;) { 845 /* Prepare header of the next frame, 846 * before previous one went down. */ 847 if (iter.frag) { 848 bool first_frag = (iter.offset == 0); 849 850 IPCB(iter.frag)->flags = IPCB(skb)->flags; 851 ip_fraglist_prepare(skb, &iter); 852 if (first_frag && IPCB(skb)->opt.optlen) { 853 /* ipcb->opt is not populated for frags 854 * coming from __ip_make_skb(), 855 * ip_options_fragment() needs optlen 856 */ 857 IPCB(iter.frag)->opt.optlen = 858 IPCB(skb)->opt.optlen; 859 ip_options_fragment(iter.frag); 860 ip_send_check(iter.iph); 861 } 862 } 863 864 skb->tstamp = tstamp; 865 err = output(net, sk, skb); 866 867 if (!err) 868 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES); 869 if (err || !iter.frag) 870 break; 871 872 skb = ip_fraglist_next(&iter); 873 } 874 875 if (err == 0) { 876 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS); 877 return 0; 878 } 879 880 kfree_skb_list(iter.frag); 881 882 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 883 return err; 884 885slow_path_clean: 886 skb_walk_frags(skb, frag2) { 887 if (frag2 == frag) 888 break; 889 frag2->sk = NULL; 890 frag2->destructor = NULL; 891 skb->truesize += frag2->truesize; 892 } 893 } 894 895slow_path: 896 /* 897 * Fragment the datagram. 898 */ 899 900 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU, 901 &state); 902 903 /* 904 * Keep copying data until we run out. 905 */ 906 907 while (state.left > 0) { 908 bool first_frag = (state.offset == 0); 909 910 skb2 = ip_frag_next(skb, &state); 911 if (IS_ERR(skb2)) { 912 err = PTR_ERR(skb2); 913 goto fail; 914 } 915 ip_frag_ipcb(skb, skb2, first_frag); 916 917 /* 918 * Put this fragment into the sending queue. 919 */ 920 skb2->tstamp = tstamp; 921 err = output(net, sk, skb2); 922 if (err) 923 goto fail; 924 925 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES); 926 } 927 consume_skb(skb); 928 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS); 929 return err; 930 931fail: 932 kfree_skb(skb); 933 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 934 return err; 935} 936EXPORT_SYMBOL(ip_do_fragment); 937 938int 939ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 940{ 941 struct msghdr *msg = from; 942 943 if (skb->ip_summed == CHECKSUM_PARTIAL) { 944 if (!copy_from_iter_full(to, len, &msg->msg_iter)) 945 return -EFAULT; 946 } else { 947 __wsum csum = 0; 948 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter)) 949 return -EFAULT; 950 skb->csum = csum_block_add(skb->csum, csum, odd); 951 } 952 return 0; 953} 954EXPORT_SYMBOL(ip_generic_getfrag); 955 956static inline __wsum 957csum_page(struct page *page, int offset, int copy) 958{ 959 char *kaddr; 960 __wsum csum; 961 kaddr = kmap(page); 962 csum = csum_partial(kaddr + offset, copy, 0); 963 kunmap(page); 964 return csum; 965} 966 967static int __ip_append_data(struct sock *sk, 968 struct flowi4 *fl4, 969 struct sk_buff_head *queue, 970 struct inet_cork *cork, 971 struct page_frag *pfrag, 972 int getfrag(void *from, char *to, int offset, 973 int len, int odd, struct sk_buff *skb), 974 void *from, int length, int transhdrlen, 975 unsigned int flags) 976{ 977 struct inet_sock *inet = inet_sk(sk); 978 struct ubuf_info *uarg = NULL; 979 struct sk_buff *skb; 980 981 struct ip_options *opt = cork->opt; 982 int hh_len; 983 int exthdrlen; 984 int mtu; 985 int copy; 986 int err; 987 int offset = 0; 988 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 989 int csummode = CHECKSUM_NONE; 990 struct rtable *rt = (struct rtable *)cork->dst; 991 unsigned int wmem_alloc_delta = 0; 992 bool paged, extra_uref = false; 993 u32 tskey = 0; 994 995 skb = skb_peek_tail(queue); 996 997 exthdrlen = !skb ? rt->dst.header_len : 0; 998 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize; 999 paged = !!cork->gso_size; 1000 1001 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && 1002 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) 1003 tskey = sk->sk_tskey++; 1004 1005 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1006 1007 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1008 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1009 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu; 1010 1011 if (cork->length + length > maxnonfragsize - fragheaderlen) { 1012 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1013 mtu - (opt ? opt->optlen : 0)); 1014 return -EMSGSIZE; 1015 } 1016 1017 /* 1018 * transhdrlen > 0 means that this is the first fragment and we wish 1019 * it won't be fragmented in the future. 1020 */ 1021 if (transhdrlen && 1022 length + fragheaderlen <= mtu && 1023 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) && 1024 (!(flags & MSG_MORE) || cork->gso_size) && 1025 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM))) 1026 csummode = CHECKSUM_PARTIAL; 1027 1028 if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) { 1029 uarg = sock_zerocopy_realloc(sk, length, skb_zcopy(skb)); 1030 if (!uarg) 1031 return -ENOBUFS; 1032 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */ 1033 if (rt->dst.dev->features & NETIF_F_SG && 1034 csummode == CHECKSUM_PARTIAL) { 1035 paged = true; 1036 } else { 1037 uarg->zerocopy = 0; 1038 skb_zcopy_set(skb, uarg, &extra_uref); 1039 } 1040 } 1041 1042 cork->length += length; 1043 1044 /* So, what's going on in the loop below? 1045 * 1046 * We use calculated fragment length to generate chained skb, 1047 * each of segments is IP fragment ready for sending to network after 1048 * adding appropriate IP header. 1049 */ 1050 1051 if (!skb) 1052 goto alloc_new_skb; 1053 1054 while (length > 0) { 1055 /* Check if the remaining data fits into current packet. */ 1056 copy = mtu - skb->len; 1057 if (copy < length) 1058 copy = maxfraglen - skb->len; 1059 if (copy <= 0) { 1060 char *data; 1061 unsigned int datalen; 1062 unsigned int fraglen; 1063 unsigned int fraggap; 1064 unsigned int alloclen, alloc_extra; 1065 unsigned int pagedlen; 1066 struct sk_buff *skb_prev; 1067alloc_new_skb: 1068 skb_prev = skb; 1069 if (skb_prev) 1070 fraggap = skb_prev->len - maxfraglen; 1071 else 1072 fraggap = 0; 1073 1074 /* 1075 * If remaining data exceeds the mtu, 1076 * we know we need more fragment(s). 1077 */ 1078 datalen = length + fraggap; 1079 if (datalen > mtu - fragheaderlen) 1080 datalen = maxfraglen - fragheaderlen; 1081 fraglen = datalen + fragheaderlen; 1082 pagedlen = 0; 1083 1084 alloc_extra = hh_len + 15; 1085 alloc_extra += exthdrlen; 1086 1087 /* The last fragment gets additional space at tail. 1088 * Note, with MSG_MORE we overallocate on fragments, 1089 * because we have no idea what fragment will be 1090 * the last. 1091 */ 1092 if (datalen == length + fraggap) 1093 alloc_extra += rt->dst.trailer_len; 1094 1095 if ((flags & MSG_MORE) && 1096 !(rt->dst.dev->features&NETIF_F_SG)) 1097 alloclen = mtu; 1098 else if (!paged && 1099 (fraglen + alloc_extra < SKB_MAX_ALLOC || 1100 !(rt->dst.dev->features & NETIF_F_SG))) 1101 alloclen = fraglen; 1102 else { 1103 alloclen = min_t(int, fraglen, MAX_HEADER); 1104 pagedlen = fraglen - alloclen; 1105 } 1106 1107 alloclen += alloc_extra; 1108 1109 if (transhdrlen) { 1110 skb = sock_alloc_send_skb(sk, alloclen, 1111 (flags & MSG_DONTWAIT), &err); 1112 } else { 1113 skb = NULL; 1114 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <= 1115 2 * sk->sk_sndbuf) 1116 skb = alloc_skb(alloclen, 1117 sk->sk_allocation); 1118 if (unlikely(!skb)) 1119 err = -ENOBUFS; 1120 } 1121 if (!skb) 1122 goto error; 1123 1124 /* 1125 * Fill in the control structures 1126 */ 1127 skb->ip_summed = csummode; 1128 skb->csum = 0; 1129 skb_reserve(skb, hh_len); 1130 1131 /* 1132 * Find where to start putting bytes. 1133 */ 1134 data = skb_put(skb, fraglen + exthdrlen - pagedlen); 1135 skb_set_network_header(skb, exthdrlen); 1136 skb->transport_header = (skb->network_header + 1137 fragheaderlen); 1138 data += fragheaderlen + exthdrlen; 1139 1140 if (fraggap) { 1141 skb->csum = skb_copy_and_csum_bits( 1142 skb_prev, maxfraglen, 1143 data + transhdrlen, fraggap); 1144 skb_prev->csum = csum_sub(skb_prev->csum, 1145 skb->csum); 1146 data += fraggap; 1147 pskb_trim_unique(skb_prev, maxfraglen); 1148 } 1149 1150 copy = datalen - transhdrlen - fraggap - pagedlen; 1151 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 1152 err = -EFAULT; 1153 kfree_skb(skb); 1154 goto error; 1155 } 1156 1157 offset += copy; 1158 length -= copy + transhdrlen; 1159 transhdrlen = 0; 1160 exthdrlen = 0; 1161 csummode = CHECKSUM_NONE; 1162 1163 /* only the initial fragment is time stamped */ 1164 skb_shinfo(skb)->tx_flags = cork->tx_flags; 1165 cork->tx_flags = 0; 1166 skb_shinfo(skb)->tskey = tskey; 1167 tskey = 0; 1168 skb_zcopy_set(skb, uarg, &extra_uref); 1169 1170 if ((flags & MSG_CONFIRM) && !skb_prev) 1171 skb_set_dst_pending_confirm(skb, 1); 1172 1173 /* 1174 * Put the packet on the pending queue. 1175 */ 1176 if (!skb->destructor) { 1177 skb->destructor = sock_wfree; 1178 skb->sk = sk; 1179 wmem_alloc_delta += skb->truesize; 1180 } 1181 __skb_queue_tail(queue, skb); 1182 continue; 1183 } 1184 1185 if (copy > length) 1186 copy = length; 1187 1188 if (!(rt->dst.dev->features&NETIF_F_SG) && 1189 skb_tailroom(skb) >= copy) { 1190 unsigned int off; 1191 1192 off = skb->len; 1193 if (getfrag(from, skb_put(skb, copy), 1194 offset, copy, off, skb) < 0) { 1195 __skb_trim(skb, off); 1196 err = -EFAULT; 1197 goto error; 1198 } 1199 } else if (!uarg || !uarg->zerocopy) { 1200 int i = skb_shinfo(skb)->nr_frags; 1201 1202 err = -ENOMEM; 1203 if (!sk_page_frag_refill(sk, pfrag)) 1204 goto error; 1205 1206 if (!skb_can_coalesce(skb, i, pfrag->page, 1207 pfrag->offset)) { 1208 err = -EMSGSIZE; 1209 if (i == MAX_SKB_FRAGS) 1210 goto error; 1211 1212 __skb_fill_page_desc(skb, i, pfrag->page, 1213 pfrag->offset, 0); 1214 skb_shinfo(skb)->nr_frags = ++i; 1215 get_page(pfrag->page); 1216 } 1217 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1218 if (getfrag(from, 1219 page_address(pfrag->page) + pfrag->offset, 1220 offset, copy, skb->len, skb) < 0) 1221 goto error_efault; 1222 1223 pfrag->offset += copy; 1224 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1225 skb->len += copy; 1226 skb->data_len += copy; 1227 skb->truesize += copy; 1228 wmem_alloc_delta += copy; 1229 } else { 1230 err = skb_zerocopy_iter_dgram(skb, from, copy); 1231 if (err < 0) 1232 goto error; 1233 } 1234 offset += copy; 1235 length -= copy; 1236 } 1237 1238 if (wmem_alloc_delta) 1239 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); 1240 return 0; 1241 1242error_efault: 1243 err = -EFAULT; 1244error: 1245 if (uarg) 1246 sock_zerocopy_put_abort(uarg, extra_uref); 1247 cork->length -= length; 1248 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1249 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); 1250 return err; 1251} 1252 1253static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1254 struct ipcm_cookie *ipc, struct rtable **rtp) 1255{ 1256 struct ip_options_rcu *opt; 1257 struct rtable *rt; 1258 1259 rt = *rtp; 1260 if (unlikely(!rt)) 1261 return -EFAULT; 1262 1263 cork->fragsize = ip_sk_use_pmtu(sk) ? 1264 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu); 1265 1266 if (!inetdev_valid_mtu(cork->fragsize)) 1267 return -ENETUNREACH; 1268 1269 /* 1270 * setup for corking. 1271 */ 1272 opt = ipc->opt; 1273 if (opt) { 1274 if (!cork->opt) { 1275 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1276 sk->sk_allocation); 1277 if (unlikely(!cork->opt)) 1278 return -ENOBUFS; 1279 } 1280 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1281 cork->flags |= IPCORK_OPT; 1282 cork->addr = ipc->addr; 1283 } 1284 1285 cork->gso_size = ipc->gso_size; 1286 1287 cork->dst = &rt->dst; 1288 /* We stole this route, caller should not release it. */ 1289 *rtp = NULL; 1290 1291 cork->length = 0; 1292 cork->ttl = ipc->ttl; 1293 cork->tos = ipc->tos; 1294 cork->mark = ipc->sockc.mark; 1295 cork->priority = ipc->priority; 1296 cork->transmit_time = ipc->sockc.transmit_time; 1297 cork->tx_flags = 0; 1298 sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags); 1299 1300 return 0; 1301} 1302 1303/* 1304 * ip_append_data() and ip_append_page() can make one large IP datagram 1305 * from many pieces of data. Each pieces will be holded on the socket 1306 * until ip_push_pending_frames() is called. Each piece can be a page 1307 * or non-page data. 1308 * 1309 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1310 * this interface potentially. 1311 * 1312 * LATER: length must be adjusted by pad at tail, when it is required. 1313 */ 1314int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1315 int getfrag(void *from, char *to, int offset, int len, 1316 int odd, struct sk_buff *skb), 1317 void *from, int length, int transhdrlen, 1318 struct ipcm_cookie *ipc, struct rtable **rtp, 1319 unsigned int flags) 1320{ 1321 struct inet_sock *inet = inet_sk(sk); 1322 int err; 1323 1324 if (flags&MSG_PROBE) 1325 return 0; 1326 1327 if (skb_queue_empty(&sk->sk_write_queue)) { 1328 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1329 if (err) 1330 return err; 1331 } else { 1332 transhdrlen = 0; 1333 } 1334 1335 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1336 sk_page_frag(sk), getfrag, 1337 from, length, transhdrlen, flags); 1338} 1339 1340ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1341 int offset, size_t size, int flags) 1342{ 1343 struct inet_sock *inet = inet_sk(sk); 1344 struct sk_buff *skb; 1345 struct rtable *rt; 1346 struct ip_options *opt = NULL; 1347 struct inet_cork *cork; 1348 int hh_len; 1349 int mtu; 1350 int len; 1351 int err; 1352 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize; 1353 1354 if (inet->hdrincl) 1355 return -EPERM; 1356 1357 if (flags&MSG_PROBE) 1358 return 0; 1359 1360 if (skb_queue_empty(&sk->sk_write_queue)) 1361 return -EINVAL; 1362 1363 cork = &inet->cork.base; 1364 rt = (struct rtable *)cork->dst; 1365 if (cork->flags & IPCORK_OPT) 1366 opt = cork->opt; 1367 1368 if (!(rt->dst.dev->features & NETIF_F_SG)) 1369 return -EOPNOTSUPP; 1370 1371 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1372 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize; 1373 1374 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1375 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1376 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 1377 1378 if (cork->length + size > maxnonfragsize - fragheaderlen) { 1379 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1380 mtu - (opt ? opt->optlen : 0)); 1381 return -EMSGSIZE; 1382 } 1383 1384 skb = skb_peek_tail(&sk->sk_write_queue); 1385 if (!skb) 1386 return -EINVAL; 1387 1388 cork->length += size; 1389 1390 while (size > 0) { 1391 /* Check if the remaining data fits into current packet. */ 1392 len = mtu - skb->len; 1393 if (len < size) 1394 len = maxfraglen - skb->len; 1395 1396 if (len <= 0) { 1397 struct sk_buff *skb_prev; 1398 int alloclen; 1399 1400 skb_prev = skb; 1401 fraggap = skb_prev->len - maxfraglen; 1402 1403 alloclen = fragheaderlen + hh_len + fraggap + 15; 1404 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1405 if (unlikely(!skb)) { 1406 err = -ENOBUFS; 1407 goto error; 1408 } 1409 1410 /* 1411 * Fill in the control structures 1412 */ 1413 skb->ip_summed = CHECKSUM_NONE; 1414 skb->csum = 0; 1415 skb_reserve(skb, hh_len); 1416 1417 /* 1418 * Find where to start putting bytes. 1419 */ 1420 skb_put(skb, fragheaderlen + fraggap); 1421 skb_reset_network_header(skb); 1422 skb->transport_header = (skb->network_header + 1423 fragheaderlen); 1424 if (fraggap) { 1425 skb->csum = skb_copy_and_csum_bits(skb_prev, 1426 maxfraglen, 1427 skb_transport_header(skb), 1428 fraggap); 1429 skb_prev->csum = csum_sub(skb_prev->csum, 1430 skb->csum); 1431 pskb_trim_unique(skb_prev, maxfraglen); 1432 } 1433 1434 /* 1435 * Put the packet on the pending queue. 1436 */ 1437 __skb_queue_tail(&sk->sk_write_queue, skb); 1438 continue; 1439 } 1440 1441 if (len > size) 1442 len = size; 1443 1444 if (skb_append_pagefrags(skb, page, offset, len)) { 1445 err = -EMSGSIZE; 1446 goto error; 1447 } 1448 1449 if (skb->ip_summed == CHECKSUM_NONE) { 1450 __wsum csum; 1451 csum = csum_page(page, offset, len); 1452 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1453 } 1454 1455 skb->len += len; 1456 skb->data_len += len; 1457 skb->truesize += len; 1458 refcount_add(len, &sk->sk_wmem_alloc); 1459 offset += len; 1460 size -= len; 1461 } 1462 return 0; 1463 1464error: 1465 cork->length -= size; 1466 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1467 return err; 1468} 1469 1470static void ip_cork_release(struct inet_cork *cork) 1471{ 1472 cork->flags &= ~IPCORK_OPT; 1473 kfree(cork->opt); 1474 cork->opt = NULL; 1475 dst_release(cork->dst); 1476 cork->dst = NULL; 1477} 1478 1479/* 1480 * Combined all pending IP fragments on the socket as one IP datagram 1481 * and push them out. 1482 */ 1483struct sk_buff *__ip_make_skb(struct sock *sk, 1484 struct flowi4 *fl4, 1485 struct sk_buff_head *queue, 1486 struct inet_cork *cork) 1487{ 1488 struct sk_buff *skb, *tmp_skb; 1489 struct sk_buff **tail_skb; 1490 struct inet_sock *inet = inet_sk(sk); 1491 struct net *net = sock_net(sk); 1492 struct ip_options *opt = NULL; 1493 struct rtable *rt = (struct rtable *)cork->dst; 1494 struct iphdr *iph; 1495 __be16 df = 0; 1496 __u8 ttl; 1497 1498 skb = __skb_dequeue(queue); 1499 if (!skb) 1500 goto out; 1501 tail_skb = &(skb_shinfo(skb)->frag_list); 1502 1503 /* move skb->data to ip header from ext header */ 1504 if (skb->data < skb_network_header(skb)) 1505 __skb_pull(skb, skb_network_offset(skb)); 1506 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1507 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1508 *tail_skb = tmp_skb; 1509 tail_skb = &(tmp_skb->next); 1510 skb->len += tmp_skb->len; 1511 skb->data_len += tmp_skb->len; 1512 skb->truesize += tmp_skb->truesize; 1513 tmp_skb->destructor = NULL; 1514 tmp_skb->sk = NULL; 1515 } 1516 1517 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1518 * to fragment the frame generated here. No matter, what transforms 1519 * how transforms change size of the packet, it will come out. 1520 */ 1521 skb->ignore_df = ip_sk_ignore_df(sk); 1522 1523 /* DF bit is set when we want to see DF on outgoing frames. 1524 * If ignore_df is set too, we still allow to fragment this frame 1525 * locally. */ 1526 if (inet->pmtudisc == IP_PMTUDISC_DO || 1527 inet->pmtudisc == IP_PMTUDISC_PROBE || 1528 (skb->len <= dst_mtu(&rt->dst) && 1529 ip_dont_fragment(sk, &rt->dst))) 1530 df = htons(IP_DF); 1531 1532 if (cork->flags & IPCORK_OPT) 1533 opt = cork->opt; 1534 1535 if (cork->ttl != 0) 1536 ttl = cork->ttl; 1537 else if (rt->rt_type == RTN_MULTICAST) 1538 ttl = inet->mc_ttl; 1539 else 1540 ttl = ip_select_ttl(inet, &rt->dst); 1541 1542 iph = ip_hdr(skb); 1543 iph->version = 4; 1544 iph->ihl = 5; 1545 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos; 1546 iph->frag_off = df; 1547 iph->ttl = ttl; 1548 iph->protocol = sk->sk_protocol; 1549 ip_copy_addrs(iph, fl4); 1550 ip_select_ident(net, skb, sk); 1551 1552 if (opt) { 1553 iph->ihl += opt->optlen >> 2; 1554 ip_options_build(skb, opt, cork->addr, rt, 0); 1555 } 1556 1557 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority; 1558 skb->mark = cork->mark; 1559 skb->tstamp = cork->transmit_time; 1560 /* 1561 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1562 * on dst refcount 1563 */ 1564 cork->dst = NULL; 1565 skb_dst_set(skb, &rt->dst); 1566 1567 if (iph->protocol == IPPROTO_ICMP) { 1568 u8 icmp_type; 1569 1570 /* For such sockets, transhdrlen is zero when do ip_append_data(), 1571 * so icmphdr does not in skb linear region and can not get icmp_type 1572 * by icmp_hdr(skb)->type. 1573 */ 1574 if (sk->sk_type == SOCK_RAW && !inet_sk(sk)->hdrincl) 1575 icmp_type = fl4->fl4_icmp_type; 1576 else 1577 icmp_type = icmp_hdr(skb)->type; 1578 icmp_out_count(net, icmp_type); 1579 } 1580 1581 ip_cork_release(cork); 1582out: 1583 return skb; 1584} 1585 1586int ip_send_skb(struct net *net, struct sk_buff *skb) 1587{ 1588 int err; 1589 1590 err = ip_local_out(net, skb->sk, skb); 1591 if (err) { 1592 if (err > 0) 1593 err = net_xmit_errno(err); 1594 if (err) 1595 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1596 } 1597 1598 return err; 1599} 1600 1601int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1602{ 1603 struct sk_buff *skb; 1604 1605 skb = ip_finish_skb(sk, fl4); 1606 if (!skb) 1607 return 0; 1608 1609 /* Netfilter gets whole the not fragmented skb. */ 1610 return ip_send_skb(sock_net(sk), skb); 1611} 1612 1613/* 1614 * Throw away all pending data on the socket. 1615 */ 1616static void __ip_flush_pending_frames(struct sock *sk, 1617 struct sk_buff_head *queue, 1618 struct inet_cork *cork) 1619{ 1620 struct sk_buff *skb; 1621 1622 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1623 kfree_skb(skb); 1624 1625 ip_cork_release(cork); 1626} 1627 1628void ip_flush_pending_frames(struct sock *sk) 1629{ 1630 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1631} 1632 1633struct sk_buff *ip_make_skb(struct sock *sk, 1634 struct flowi4 *fl4, 1635 int getfrag(void *from, char *to, int offset, 1636 int len, int odd, struct sk_buff *skb), 1637 void *from, int length, int transhdrlen, 1638 struct ipcm_cookie *ipc, struct rtable **rtp, 1639 struct inet_cork *cork, unsigned int flags) 1640{ 1641 struct sk_buff_head queue; 1642 int err; 1643 1644 if (flags & MSG_PROBE) 1645 return NULL; 1646 1647 __skb_queue_head_init(&queue); 1648 1649 cork->flags = 0; 1650 cork->addr = 0; 1651 cork->opt = NULL; 1652 err = ip_setup_cork(sk, cork, ipc, rtp); 1653 if (err) 1654 return ERR_PTR(err); 1655 1656 err = __ip_append_data(sk, fl4, &queue, cork, 1657 ¤t->task_frag, getfrag, 1658 from, length, transhdrlen, flags); 1659 if (err) { 1660 __ip_flush_pending_frames(sk, &queue, cork); 1661 return ERR_PTR(err); 1662 } 1663 1664 return __ip_make_skb(sk, fl4, &queue, cork); 1665} 1666 1667/* 1668 * Fetch data from kernel space and fill in checksum if needed. 1669 */ 1670static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1671 int len, int odd, struct sk_buff *skb) 1672{ 1673 __wsum csum; 1674 1675 csum = csum_partial_copy_nocheck(dptr+offset, to, len); 1676 skb->csum = csum_block_add(skb->csum, csum, odd); 1677 return 0; 1678} 1679 1680/* 1681 * Generic function to send a packet as reply to another packet. 1682 * Used to send some TCP resets/acks so far. 1683 */ 1684void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb, 1685 const struct ip_options *sopt, 1686 __be32 daddr, __be32 saddr, 1687 const struct ip_reply_arg *arg, 1688 unsigned int len, u64 transmit_time) 1689{ 1690 struct ip_options_data replyopts; 1691 struct ipcm_cookie ipc; 1692 struct flowi4 fl4; 1693 struct rtable *rt = skb_rtable(skb); 1694 struct net *net = sock_net(sk); 1695 struct sk_buff *nskb; 1696 int err; 1697 int oif; 1698 1699 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt)) 1700 return; 1701 1702 ipcm_init(&ipc); 1703 ipc.addr = daddr; 1704 ipc.sockc.transmit_time = transmit_time; 1705 1706 if (replyopts.opt.opt.optlen) { 1707 ipc.opt = &replyopts.opt; 1708 1709 if (replyopts.opt.opt.srr) 1710 daddr = replyopts.opt.opt.faddr; 1711 } 1712 1713 oif = arg->bound_dev_if; 1714 if (!oif && netif_index_is_l3_master(net, skb->skb_iif)) 1715 oif = skb->skb_iif; 1716 1717 flowi4_init_output(&fl4, oif, 1718 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark, 1719 RT_TOS(arg->tos), 1720 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1721 ip_reply_arg_flowi_flags(arg), 1722 daddr, saddr, 1723 tcp_hdr(skb)->source, tcp_hdr(skb)->dest, 1724 arg->uid); 1725 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 1726 rt = ip_route_output_flow(net, &fl4, sk); 1727 if (IS_ERR(rt)) 1728 return; 1729 1730 inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK; 1731 1732 sk->sk_protocol = ip_hdr(skb)->protocol; 1733 sk->sk_bound_dev_if = arg->bound_dev_if; 1734 sk->sk_sndbuf = READ_ONCE(sysctl_wmem_default); 1735 ipc.sockc.mark = fl4.flowi4_mark; 1736 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, 1737 len, 0, &ipc, &rt, MSG_DONTWAIT); 1738 if (unlikely(err)) { 1739 ip_flush_pending_frames(sk); 1740 goto out; 1741 } 1742 1743 nskb = skb_peek(&sk->sk_write_queue); 1744 if (nskb) { 1745 if (arg->csumoffset >= 0) 1746 *((__sum16 *)skb_transport_header(nskb) + 1747 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1748 arg->csum)); 1749 nskb->ip_summed = CHECKSUM_NONE; 1750 ip_push_pending_frames(sk, &fl4); 1751 } 1752out: 1753 ip_rt_put(rt); 1754} 1755 1756void __init ip_init(void) 1757{ 1758 ip_rt_init(); 1759 inet_initpeers(); 1760 1761#if defined(CONFIG_IP_MULTICAST) 1762 igmp_mc_init(); 1763#endif 1764} 1765