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/lwtunnel.h> 79 #include <net/inet_dscp.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 87 static int 88 ip_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. */ 93 void ip_send_check(struct iphdr *iph) 94 { 95 iph->check = 0; 96 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 97 } 98 EXPORT_SYMBOL(ip_send_check); 99 100 int __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 } 122 123 int 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 } 133 EXPORT_SYMBOL_GPL(ip_local_out); 134 135 static 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 */ 149 int 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 } 196 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 197 198 static 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 = dst_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 } 246 247 static 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 } 294 295 static 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 } 315 316 static 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 } 331 332 static 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 } 365 366 int 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 } 425 426 int 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 } 438 EXPORT_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 */ 446 static 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 */ 456 int __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 = dst_rtable(__sk_dst_check(sk, 0)); 479 if (!rt) { 480 inet_sk_init_flowi4(inet, fl4); 481 482 /* sctp_v4_xmit() uses its own DSCP value */ 483 fl4->flowi4_tos = tos & INET_DSCP_MASK; 484 485 /* If this fails, retransmit mechanism of transport layer will 486 * keep trying until route appears or the connection times 487 * itself out. 488 */ 489 rt = ip_route_output_flow(net, fl4, sk); 490 if (IS_ERR(rt)) 491 goto no_route; 492 sk_setup_caps(sk, &rt->dst); 493 } 494 skb_dst_set_noref(skb, &rt->dst); 495 496 packet_routed: 497 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) 498 goto no_route; 499 500 /* OK, we know where to send it, allocate and build IP header. */ 501 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 502 skb_reset_network_header(skb); 503 iph = ip_hdr(skb); 504 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff)); 505 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df) 506 iph->frag_off = htons(IP_DF); 507 else 508 iph->frag_off = 0; 509 iph->ttl = ip_select_ttl(inet, &rt->dst); 510 iph->protocol = sk->sk_protocol; 511 ip_copy_addrs(iph, fl4); 512 513 /* Transport layer set skb->h.foo itself. */ 514 515 if (inet_opt && inet_opt->opt.optlen) { 516 iph->ihl += inet_opt->opt.optlen >> 2; 517 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt); 518 } 519 520 ip_select_ident_segs(net, skb, sk, 521 skb_shinfo(skb)->gso_segs ?: 1); 522 523 /* TODO : should we use skb->sk here instead of sk ? */ 524 skb->priority = READ_ONCE(sk->sk_priority); 525 skb->mark = READ_ONCE(sk->sk_mark); 526 527 res = ip_local_out(net, sk, skb); 528 rcu_read_unlock(); 529 return res; 530 531 no_route: 532 rcu_read_unlock(); 533 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 534 kfree_skb_reason(skb, SKB_DROP_REASON_IP_OUTNOROUTES); 535 return -EHOSTUNREACH; 536 } 537 EXPORT_SYMBOL(__ip_queue_xmit); 538 539 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl) 540 { 541 return __ip_queue_xmit(sk, skb, fl, READ_ONCE(inet_sk(sk)->tos)); 542 } 543 EXPORT_SYMBOL(ip_queue_xmit); 544 545 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 546 { 547 to->pkt_type = from->pkt_type; 548 to->priority = from->priority; 549 to->protocol = from->protocol; 550 to->skb_iif = from->skb_iif; 551 skb_dst_drop(to); 552 skb_dst_copy(to, from); 553 to->dev = from->dev; 554 to->mark = from->mark; 555 556 skb_copy_hash(to, from); 557 558 #ifdef CONFIG_NET_SCHED 559 to->tc_index = from->tc_index; 560 #endif 561 nf_copy(to, from); 562 skb_ext_copy(to, from); 563 #if IS_ENABLED(CONFIG_IP_VS) 564 to->ipvs_property = from->ipvs_property; 565 #endif 566 skb_copy_secmark(to, from); 567 } 568 569 static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 570 unsigned int mtu, 571 int (*output)(struct net *, struct sock *, struct sk_buff *)) 572 { 573 struct iphdr *iph = ip_hdr(skb); 574 575 if ((iph->frag_off & htons(IP_DF)) == 0) 576 return ip_do_fragment(net, sk, skb, output); 577 578 if (unlikely(!skb->ignore_df || 579 (IPCB(skb)->frag_max_size && 580 IPCB(skb)->frag_max_size > mtu))) { 581 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 582 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 583 htonl(mtu)); 584 kfree_skb(skb); 585 return -EMSGSIZE; 586 } 587 588 return ip_do_fragment(net, sk, skb, output); 589 } 590 591 void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph, 592 unsigned int hlen, struct ip_fraglist_iter *iter) 593 { 594 unsigned int first_len = skb_pagelen(skb); 595 596 iter->frag = skb_shinfo(skb)->frag_list; 597 skb_frag_list_init(skb); 598 599 iter->offset = 0; 600 iter->iph = iph; 601 iter->hlen = hlen; 602 603 skb->data_len = first_len - skb_headlen(skb); 604 skb->len = first_len; 605 iph->tot_len = htons(first_len); 606 iph->frag_off = htons(IP_MF); 607 ip_send_check(iph); 608 } 609 EXPORT_SYMBOL(ip_fraglist_init); 610 611 void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter) 612 { 613 unsigned int hlen = iter->hlen; 614 struct iphdr *iph = iter->iph; 615 struct sk_buff *frag; 616 617 frag = iter->frag; 618 frag->ip_summed = CHECKSUM_NONE; 619 skb_reset_transport_header(frag); 620 __skb_push(frag, hlen); 621 skb_reset_network_header(frag); 622 memcpy(skb_network_header(frag), iph, hlen); 623 iter->iph = ip_hdr(frag); 624 iph = iter->iph; 625 iph->tot_len = htons(frag->len); 626 ip_copy_metadata(frag, skb); 627 iter->offset += skb->len - hlen; 628 iph->frag_off = htons(iter->offset >> 3); 629 if (frag->next) 630 iph->frag_off |= htons(IP_MF); 631 /* Ready, complete checksum */ 632 ip_send_check(iph); 633 } 634 EXPORT_SYMBOL(ip_fraglist_prepare); 635 636 void ip_frag_init(struct sk_buff *skb, unsigned int hlen, 637 unsigned int ll_rs, unsigned int mtu, bool DF, 638 struct ip_frag_state *state) 639 { 640 struct iphdr *iph = ip_hdr(skb); 641 642 state->DF = DF; 643 state->hlen = hlen; 644 state->ll_rs = ll_rs; 645 state->mtu = mtu; 646 647 state->left = skb->len - hlen; /* Space per frame */ 648 state->ptr = hlen; /* Where to start from */ 649 650 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 651 state->not_last_frag = iph->frag_off & htons(IP_MF); 652 } 653 EXPORT_SYMBOL(ip_frag_init); 654 655 static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to, 656 bool first_frag) 657 { 658 /* Copy the flags to each fragment. */ 659 IPCB(to)->flags = IPCB(from)->flags; 660 661 /* ANK: dirty, but effective trick. Upgrade options only if 662 * the segment to be fragmented was THE FIRST (otherwise, 663 * options are already fixed) and make it ONCE 664 * on the initial skb, so that all the following fragments 665 * will inherit fixed options. 666 */ 667 if (first_frag) 668 ip_options_fragment(from); 669 } 670 671 struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state) 672 { 673 unsigned int len = state->left; 674 struct sk_buff *skb2; 675 struct iphdr *iph; 676 677 /* IF: it doesn't fit, use 'mtu' - the data space left */ 678 if (len > state->mtu) 679 len = state->mtu; 680 /* IF: we are not sending up to and including the packet end 681 then align the next start on an eight byte boundary */ 682 if (len < state->left) { 683 len &= ~7; 684 } 685 686 /* Allocate buffer */ 687 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC); 688 if (!skb2) 689 return ERR_PTR(-ENOMEM); 690 691 /* 692 * Set up data on packet 693 */ 694 695 ip_copy_metadata(skb2, skb); 696 skb_reserve(skb2, state->ll_rs); 697 skb_put(skb2, len + state->hlen); 698 skb_reset_network_header(skb2); 699 skb2->transport_header = skb2->network_header + state->hlen; 700 701 /* 702 * Charge the memory for the fragment to any owner 703 * it might possess 704 */ 705 706 if (skb->sk) 707 skb_set_owner_w(skb2, skb->sk); 708 709 /* 710 * Copy the packet header into the new buffer. 711 */ 712 713 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen); 714 715 /* 716 * Copy a block of the IP datagram. 717 */ 718 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len)) 719 BUG(); 720 state->left -= len; 721 722 /* 723 * Fill in the new header fields. 724 */ 725 iph = ip_hdr(skb2); 726 iph->frag_off = htons((state->offset >> 3)); 727 if (state->DF) 728 iph->frag_off |= htons(IP_DF); 729 730 /* 731 * Added AC : If we are fragmenting a fragment that's not the 732 * last fragment then keep MF on each bit 733 */ 734 if (state->left > 0 || state->not_last_frag) 735 iph->frag_off |= htons(IP_MF); 736 state->ptr += len; 737 state->offset += len; 738 739 iph->tot_len = htons(len + state->hlen); 740 741 ip_send_check(iph); 742 743 return skb2; 744 } 745 EXPORT_SYMBOL(ip_frag_next); 746 747 /* 748 * This IP datagram is too large to be sent in one piece. Break it up into 749 * smaller pieces (each of size equal to IP header plus 750 * a block of the data of the original IP data part) that will yet fit in a 751 * single device frame, and queue such a frame for sending. 752 */ 753 754 int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 755 int (*output)(struct net *, struct sock *, struct sk_buff *)) 756 { 757 struct iphdr *iph; 758 struct sk_buff *skb2; 759 u8 tstamp_type = skb->tstamp_type; 760 struct rtable *rt = skb_rtable(skb); 761 unsigned int mtu, hlen, ll_rs; 762 struct ip_fraglist_iter iter; 763 ktime_t tstamp = skb->tstamp; 764 struct ip_frag_state state; 765 int err = 0; 766 767 /* for offloaded checksums cleanup checksum before fragmentation */ 768 if (skb->ip_summed == CHECKSUM_PARTIAL && 769 (err = skb_checksum_help(skb))) 770 goto fail; 771 772 /* 773 * Point into the IP datagram header. 774 */ 775 776 iph = ip_hdr(skb); 777 778 mtu = ip_skb_dst_mtu(sk, skb); 779 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu) 780 mtu = IPCB(skb)->frag_max_size; 781 782 /* 783 * Setup starting values. 784 */ 785 786 hlen = iph->ihl * 4; 787 mtu = mtu - hlen; /* Size of data space */ 788 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 789 ll_rs = LL_RESERVED_SPACE(rt->dst.dev); 790 791 /* When frag_list is given, use it. First, check its validity: 792 * some transformers could create wrong frag_list or break existing 793 * one, it is not prohibited. In this case fall back to copying. 794 * 795 * LATER: this step can be merged to real generation of fragments, 796 * we can switch to copy when see the first bad fragment. 797 */ 798 if (skb_has_frag_list(skb)) { 799 struct sk_buff *frag, *frag2; 800 unsigned int first_len = skb_pagelen(skb); 801 802 if (first_len - hlen > mtu || 803 ((first_len - hlen) & 7) || 804 ip_is_fragment(iph) || 805 skb_cloned(skb) || 806 skb_headroom(skb) < ll_rs) 807 goto slow_path; 808 809 skb_walk_frags(skb, frag) { 810 /* Correct geometry. */ 811 if (frag->len > mtu || 812 ((frag->len & 7) && frag->next) || 813 skb_headroom(frag) < hlen + ll_rs) 814 goto slow_path_clean; 815 816 /* Partially cloned skb? */ 817 if (skb_shared(frag)) 818 goto slow_path_clean; 819 820 BUG_ON(frag->sk); 821 if (skb->sk) { 822 frag->sk = skb->sk; 823 frag->destructor = sock_wfree; 824 } 825 skb->truesize -= frag->truesize; 826 } 827 828 /* Everything is OK. Generate! */ 829 ip_fraglist_init(skb, iph, hlen, &iter); 830 831 for (;;) { 832 /* Prepare header of the next frame, 833 * before previous one went down. */ 834 if (iter.frag) { 835 bool first_frag = (iter.offset == 0); 836 837 IPCB(iter.frag)->flags = IPCB(skb)->flags; 838 ip_fraglist_prepare(skb, &iter); 839 if (first_frag && IPCB(skb)->opt.optlen) { 840 /* ipcb->opt is not populated for frags 841 * coming from __ip_make_skb(), 842 * ip_options_fragment() needs optlen 843 */ 844 IPCB(iter.frag)->opt.optlen = 845 IPCB(skb)->opt.optlen; 846 ip_options_fragment(iter.frag); 847 ip_send_check(iter.iph); 848 } 849 } 850 851 skb_set_delivery_time(skb, tstamp, tstamp_type); 852 err = output(net, sk, skb); 853 854 if (!err) 855 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES); 856 if (err || !iter.frag) 857 break; 858 859 skb = ip_fraglist_next(&iter); 860 } 861 862 if (err == 0) { 863 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS); 864 return 0; 865 } 866 867 kfree_skb_list(iter.frag); 868 869 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 870 return err; 871 872 slow_path_clean: 873 skb_walk_frags(skb, frag2) { 874 if (frag2 == frag) 875 break; 876 frag2->sk = NULL; 877 frag2->destructor = NULL; 878 skb->truesize += frag2->truesize; 879 } 880 } 881 882 slow_path: 883 /* 884 * Fragment the datagram. 885 */ 886 887 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU, 888 &state); 889 890 /* 891 * Keep copying data until we run out. 892 */ 893 894 while (state.left > 0) { 895 bool first_frag = (state.offset == 0); 896 897 skb2 = ip_frag_next(skb, &state); 898 if (IS_ERR(skb2)) { 899 err = PTR_ERR(skb2); 900 goto fail; 901 } 902 ip_frag_ipcb(skb, skb2, first_frag); 903 904 /* 905 * Put this fragment into the sending queue. 906 */ 907 skb_set_delivery_time(skb2, tstamp, tstamp_type); 908 err = output(net, sk, skb2); 909 if (err) 910 goto fail; 911 912 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES); 913 } 914 consume_skb(skb); 915 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS); 916 return err; 917 918 fail: 919 kfree_skb(skb); 920 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 921 return err; 922 } 923 EXPORT_SYMBOL(ip_do_fragment); 924 925 int 926 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 927 { 928 struct msghdr *msg = from; 929 930 if (skb->ip_summed == CHECKSUM_PARTIAL) { 931 if (!copy_from_iter_full(to, len, &msg->msg_iter)) 932 return -EFAULT; 933 } else { 934 __wsum csum = 0; 935 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter)) 936 return -EFAULT; 937 skb->csum = csum_block_add(skb->csum, csum, odd); 938 } 939 return 0; 940 } 941 EXPORT_SYMBOL(ip_generic_getfrag); 942 943 static int __ip_append_data(struct sock *sk, 944 struct flowi4 *fl4, 945 struct sk_buff_head *queue, 946 struct inet_cork *cork, 947 struct page_frag *pfrag, 948 int getfrag(void *from, char *to, int offset, 949 int len, int odd, struct sk_buff *skb), 950 void *from, int length, int transhdrlen, 951 unsigned int flags) 952 { 953 struct inet_sock *inet = inet_sk(sk); 954 struct ubuf_info *uarg = NULL; 955 struct sk_buff *skb; 956 struct ip_options *opt = cork->opt; 957 int hh_len; 958 int exthdrlen; 959 int mtu; 960 int copy; 961 int err; 962 int offset = 0; 963 bool zc = false; 964 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 965 int csummode = CHECKSUM_NONE; 966 struct rtable *rt = dst_rtable(cork->dst); 967 bool paged, hold_tskey = false, extra_uref = false; 968 unsigned int wmem_alloc_delta = 0; 969 u32 tskey = 0; 970 971 skb = skb_peek_tail(queue); 972 973 exthdrlen = !skb ? rt->dst.header_len : 0; 974 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize; 975 paged = !!cork->gso_size; 976 977 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 978 979 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 980 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 981 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu; 982 983 if (cork->length + length > maxnonfragsize - fragheaderlen) { 984 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 985 mtu - (opt ? opt->optlen : 0)); 986 return -EMSGSIZE; 987 } 988 989 /* 990 * transhdrlen > 0 means that this is the first fragment and we wish 991 * it won't be fragmented in the future. 992 */ 993 if (transhdrlen && 994 length + fragheaderlen <= mtu && 995 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) && 996 (!(flags & MSG_MORE) || cork->gso_size) && 997 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM))) 998 csummode = CHECKSUM_PARTIAL; 999 1000 if ((flags & MSG_ZEROCOPY) && length) { 1001 struct msghdr *msg = from; 1002 1003 if (getfrag == ip_generic_getfrag && msg->msg_ubuf) { 1004 if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb)) 1005 return -EINVAL; 1006 1007 /* Leave uarg NULL if can't zerocopy, callers should 1008 * be able to handle it. 1009 */ 1010 if ((rt->dst.dev->features & NETIF_F_SG) && 1011 csummode == CHECKSUM_PARTIAL) { 1012 paged = true; 1013 zc = true; 1014 uarg = msg->msg_ubuf; 1015 } 1016 } else if (sock_flag(sk, SOCK_ZEROCOPY)) { 1017 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb), 1018 false); 1019 if (!uarg) 1020 return -ENOBUFS; 1021 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */ 1022 if (rt->dst.dev->features & NETIF_F_SG && 1023 csummode == CHECKSUM_PARTIAL) { 1024 paged = true; 1025 zc = true; 1026 } else { 1027 uarg_to_msgzc(uarg)->zerocopy = 0; 1028 skb_zcopy_set(skb, uarg, &extra_uref); 1029 } 1030 } 1031 } else if ((flags & MSG_SPLICE_PAGES) && length) { 1032 if (inet_test_bit(HDRINCL, sk)) 1033 return -EPERM; 1034 if (rt->dst.dev->features & NETIF_F_SG && 1035 getfrag == ip_generic_getfrag) 1036 /* We need an empty buffer to attach stuff to */ 1037 paged = true; 1038 else 1039 flags &= ~MSG_SPLICE_PAGES; 1040 } 1041 1042 cork->length += length; 1043 1044 if (cork->tx_flags & SKBTX_ANY_TSTAMP && 1045 READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) { 1046 if (cork->flags & IPCORK_TS_OPT_ID) { 1047 tskey = cork->ts_opt_id; 1048 } else { 1049 tskey = atomic_inc_return(&sk->sk_tskey) - 1; 1050 hold_tskey = true; 1051 } 1052 } 1053 1054 /* So, what's going on in the loop below? 1055 * 1056 * We use calculated fragment length to generate chained skb, 1057 * each of segments is IP fragment ready for sending to network after 1058 * adding appropriate IP header. 1059 */ 1060 1061 if (!skb) 1062 goto alloc_new_skb; 1063 1064 while (length > 0) { 1065 /* Check if the remaining data fits into current packet. */ 1066 copy = mtu - skb->len; 1067 if (copy < length) 1068 copy = maxfraglen - skb->len; 1069 if (copy <= 0) { 1070 char *data; 1071 unsigned int datalen; 1072 unsigned int fraglen; 1073 unsigned int fraggap; 1074 unsigned int alloclen, alloc_extra; 1075 unsigned int pagedlen; 1076 struct sk_buff *skb_prev; 1077 alloc_new_skb: 1078 skb_prev = skb; 1079 if (skb_prev) 1080 fraggap = skb_prev->len - maxfraglen; 1081 else 1082 fraggap = 0; 1083 1084 /* 1085 * If remaining data exceeds the mtu, 1086 * we know we need more fragment(s). 1087 */ 1088 datalen = length + fraggap; 1089 if (datalen > mtu - fragheaderlen) 1090 datalen = maxfraglen - fragheaderlen; 1091 fraglen = datalen + fragheaderlen; 1092 pagedlen = 0; 1093 1094 alloc_extra = hh_len + 15; 1095 alloc_extra += exthdrlen; 1096 1097 /* The last fragment gets additional space at tail. 1098 * Note, with MSG_MORE we overallocate on fragments, 1099 * because we have no idea what fragment will be 1100 * the last. 1101 */ 1102 if (datalen == length + fraggap) 1103 alloc_extra += rt->dst.trailer_len; 1104 1105 if ((flags & MSG_MORE) && 1106 !(rt->dst.dev->features&NETIF_F_SG)) 1107 alloclen = mtu; 1108 else if (!paged && 1109 (fraglen + alloc_extra < SKB_MAX_ALLOC || 1110 !(rt->dst.dev->features & NETIF_F_SG))) 1111 alloclen = fraglen; 1112 else { 1113 alloclen = fragheaderlen + transhdrlen; 1114 pagedlen = datalen - transhdrlen; 1115 } 1116 1117 alloclen += alloc_extra; 1118 1119 if (transhdrlen) { 1120 skb = sock_alloc_send_skb(sk, alloclen, 1121 (flags & MSG_DONTWAIT), &err); 1122 } else { 1123 skb = NULL; 1124 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <= 1125 2 * sk->sk_sndbuf) 1126 skb = alloc_skb(alloclen, 1127 sk->sk_allocation); 1128 if (unlikely(!skb)) 1129 err = -ENOBUFS; 1130 } 1131 if (!skb) 1132 goto error; 1133 1134 /* 1135 * Fill in the control structures 1136 */ 1137 skb->ip_summed = csummode; 1138 skb->csum = 0; 1139 skb_reserve(skb, hh_len); 1140 1141 /* 1142 * Find where to start putting bytes. 1143 */ 1144 data = skb_put(skb, fraglen + exthdrlen - pagedlen); 1145 skb_set_network_header(skb, exthdrlen); 1146 skb->transport_header = (skb->network_header + 1147 fragheaderlen); 1148 data += fragheaderlen + exthdrlen; 1149 1150 if (fraggap) { 1151 skb->csum = skb_copy_and_csum_bits( 1152 skb_prev, maxfraglen, 1153 data + transhdrlen, fraggap); 1154 skb_prev->csum = csum_sub(skb_prev->csum, 1155 skb->csum); 1156 data += fraggap; 1157 pskb_trim_unique(skb_prev, maxfraglen); 1158 } 1159 1160 copy = datalen - transhdrlen - fraggap - pagedlen; 1161 /* [!] NOTE: copy will be negative if pagedlen>0 1162 * because then the equation reduces to -fraggap. 1163 */ 1164 if (copy > 0 && 1165 INDIRECT_CALL_1(getfrag, ip_generic_getfrag, 1166 from, data + transhdrlen, offset, 1167 copy, fraggap, skb) < 0) { 1168 err = -EFAULT; 1169 kfree_skb(skb); 1170 goto error; 1171 } else if (flags & MSG_SPLICE_PAGES) { 1172 copy = 0; 1173 } 1174 1175 offset += copy; 1176 length -= copy + transhdrlen; 1177 transhdrlen = 0; 1178 exthdrlen = 0; 1179 csummode = CHECKSUM_NONE; 1180 1181 /* only the initial fragment is time stamped */ 1182 skb_shinfo(skb)->tx_flags = cork->tx_flags; 1183 cork->tx_flags = 0; 1184 skb_shinfo(skb)->tskey = tskey; 1185 tskey = 0; 1186 skb_zcopy_set(skb, uarg, &extra_uref); 1187 1188 if ((flags & MSG_CONFIRM) && !skb_prev) 1189 skb_set_dst_pending_confirm(skb, 1); 1190 1191 /* 1192 * Put the packet on the pending queue. 1193 */ 1194 if (!skb->destructor) { 1195 skb->destructor = sock_wfree; 1196 skb->sk = sk; 1197 wmem_alloc_delta += skb->truesize; 1198 } 1199 __skb_queue_tail(queue, skb); 1200 continue; 1201 } 1202 1203 if (copy > length) 1204 copy = length; 1205 1206 if (!(rt->dst.dev->features&NETIF_F_SG) && 1207 skb_tailroom(skb) >= copy) { 1208 unsigned int off; 1209 1210 off = skb->len; 1211 if (INDIRECT_CALL_1(getfrag, ip_generic_getfrag, 1212 from, skb_put(skb, copy), 1213 offset, copy, off, skb) < 0) { 1214 __skb_trim(skb, off); 1215 err = -EFAULT; 1216 goto error; 1217 } 1218 } else if (flags & MSG_SPLICE_PAGES) { 1219 struct msghdr *msg = from; 1220 1221 err = -EIO; 1222 if (WARN_ON_ONCE(copy > msg->msg_iter.count)) 1223 goto error; 1224 1225 err = skb_splice_from_iter(skb, &msg->msg_iter, copy, 1226 sk->sk_allocation); 1227 if (err < 0) 1228 goto error; 1229 copy = err; 1230 wmem_alloc_delta += copy; 1231 } else if (!zc) { 1232 int i = skb_shinfo(skb)->nr_frags; 1233 1234 err = -ENOMEM; 1235 if (!sk_page_frag_refill(sk, pfrag)) 1236 goto error; 1237 1238 skb_zcopy_downgrade_managed(skb); 1239 if (!skb_can_coalesce(skb, i, pfrag->page, 1240 pfrag->offset)) { 1241 err = -EMSGSIZE; 1242 if (i == MAX_SKB_FRAGS) 1243 goto error; 1244 1245 __skb_fill_page_desc(skb, i, pfrag->page, 1246 pfrag->offset, 0); 1247 skb_shinfo(skb)->nr_frags = ++i; 1248 get_page(pfrag->page); 1249 } 1250 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1251 if (INDIRECT_CALL_1(getfrag, ip_generic_getfrag, 1252 from, 1253 page_address(pfrag->page) + pfrag->offset, 1254 offset, copy, skb->len, skb) < 0) 1255 goto error_efault; 1256 1257 pfrag->offset += copy; 1258 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1259 skb_len_add(skb, copy); 1260 wmem_alloc_delta += copy; 1261 } else { 1262 err = skb_zerocopy_iter_dgram(skb, from, copy); 1263 if (err < 0) 1264 goto error; 1265 } 1266 offset += copy; 1267 length -= copy; 1268 } 1269 1270 if (wmem_alloc_delta) 1271 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); 1272 return 0; 1273 1274 error_efault: 1275 err = -EFAULT; 1276 error: 1277 net_zcopy_put_abort(uarg, extra_uref); 1278 cork->length -= length; 1279 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1280 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); 1281 if (hold_tskey) 1282 atomic_dec(&sk->sk_tskey); 1283 return err; 1284 } 1285 1286 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1287 struct ipcm_cookie *ipc, struct rtable **rtp) 1288 { 1289 struct ip_options_rcu *opt; 1290 struct rtable *rt; 1291 1292 rt = *rtp; 1293 if (unlikely(!rt)) 1294 return -EFAULT; 1295 1296 cork->fragsize = ip_sk_use_pmtu(sk) ? 1297 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu); 1298 1299 if (!inetdev_valid_mtu(cork->fragsize)) 1300 return -ENETUNREACH; 1301 1302 /* 1303 * setup for corking. 1304 */ 1305 opt = ipc->opt; 1306 if (opt) { 1307 if (!cork->opt) { 1308 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1309 sk->sk_allocation); 1310 if (unlikely(!cork->opt)) 1311 return -ENOBUFS; 1312 } 1313 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1314 cork->flags |= IPCORK_OPT; 1315 cork->addr = ipc->addr; 1316 } 1317 1318 cork->gso_size = ipc->gso_size; 1319 1320 cork->dst = &rt->dst; 1321 /* We stole this route, caller should not release it. */ 1322 *rtp = NULL; 1323 1324 cork->length = 0; 1325 cork->ttl = ipc->ttl; 1326 cork->tos = ipc->tos; 1327 cork->mark = ipc->sockc.mark; 1328 cork->priority = ipc->sockc.priority; 1329 cork->transmit_time = ipc->sockc.transmit_time; 1330 cork->tx_flags = 0; 1331 sock_tx_timestamp(sk, &ipc->sockc, &cork->tx_flags); 1332 if (ipc->sockc.tsflags & SOCKCM_FLAG_TS_OPT_ID) { 1333 cork->flags |= IPCORK_TS_OPT_ID; 1334 cork->ts_opt_id = ipc->sockc.ts_opt_id; 1335 } 1336 1337 return 0; 1338 } 1339 1340 /* 1341 * ip_append_data() can make one large IP datagram from many pieces of 1342 * data. Each piece will be held on the socket until 1343 * ip_push_pending_frames() is called. Each piece can be a page or 1344 * non-page data. 1345 * 1346 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1347 * this interface potentially. 1348 * 1349 * LATER: length must be adjusted by pad at tail, when it is required. 1350 */ 1351 int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1352 int getfrag(void *from, char *to, int offset, int len, 1353 int odd, struct sk_buff *skb), 1354 void *from, int length, int transhdrlen, 1355 struct ipcm_cookie *ipc, struct rtable **rtp, 1356 unsigned int flags) 1357 { 1358 struct inet_sock *inet = inet_sk(sk); 1359 int err; 1360 1361 if (flags&MSG_PROBE) 1362 return 0; 1363 1364 if (skb_queue_empty(&sk->sk_write_queue)) { 1365 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1366 if (err) 1367 return err; 1368 } else { 1369 transhdrlen = 0; 1370 } 1371 1372 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1373 sk_page_frag(sk), getfrag, 1374 from, length, transhdrlen, flags); 1375 } 1376 1377 static void ip_cork_release(struct inet_cork *cork) 1378 { 1379 cork->flags &= ~IPCORK_OPT; 1380 kfree(cork->opt); 1381 cork->opt = NULL; 1382 dst_release(cork->dst); 1383 cork->dst = NULL; 1384 } 1385 1386 /* 1387 * Combined all pending IP fragments on the socket as one IP datagram 1388 * and push them out. 1389 */ 1390 struct sk_buff *__ip_make_skb(struct sock *sk, 1391 struct flowi4 *fl4, 1392 struct sk_buff_head *queue, 1393 struct inet_cork *cork) 1394 { 1395 struct sk_buff *skb, *tmp_skb; 1396 struct sk_buff **tail_skb; 1397 struct inet_sock *inet = inet_sk(sk); 1398 struct net *net = sock_net(sk); 1399 struct ip_options *opt = NULL; 1400 struct rtable *rt = dst_rtable(cork->dst); 1401 struct iphdr *iph; 1402 u8 pmtudisc, ttl; 1403 __be16 df = 0; 1404 1405 skb = __skb_dequeue(queue); 1406 if (!skb) 1407 goto out; 1408 tail_skb = &(skb_shinfo(skb)->frag_list); 1409 1410 /* move skb->data to ip header from ext header */ 1411 if (skb->data < skb_network_header(skb)) 1412 __skb_pull(skb, skb_network_offset(skb)); 1413 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1414 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1415 *tail_skb = tmp_skb; 1416 tail_skb = &(tmp_skb->next); 1417 skb->len += tmp_skb->len; 1418 skb->data_len += tmp_skb->len; 1419 skb->truesize += tmp_skb->truesize; 1420 tmp_skb->destructor = NULL; 1421 tmp_skb->sk = NULL; 1422 } 1423 1424 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1425 * to fragment the frame generated here. No matter, what transforms 1426 * how transforms change size of the packet, it will come out. 1427 */ 1428 skb->ignore_df = ip_sk_ignore_df(sk); 1429 1430 /* DF bit is set when we want to see DF on outgoing frames. 1431 * If ignore_df is set too, we still allow to fragment this frame 1432 * locally. */ 1433 pmtudisc = READ_ONCE(inet->pmtudisc); 1434 if (pmtudisc == IP_PMTUDISC_DO || 1435 pmtudisc == IP_PMTUDISC_PROBE || 1436 (skb->len <= dst_mtu(&rt->dst) && 1437 ip_dont_fragment(sk, &rt->dst))) 1438 df = htons(IP_DF); 1439 1440 if (cork->flags & IPCORK_OPT) 1441 opt = cork->opt; 1442 1443 if (cork->ttl != 0) 1444 ttl = cork->ttl; 1445 else if (rt->rt_type == RTN_MULTICAST) 1446 ttl = READ_ONCE(inet->mc_ttl); 1447 else 1448 ttl = ip_select_ttl(inet, &rt->dst); 1449 1450 iph = ip_hdr(skb); 1451 iph->version = 4; 1452 iph->ihl = 5; 1453 iph->tos = (cork->tos != -1) ? cork->tos : READ_ONCE(inet->tos); 1454 iph->frag_off = df; 1455 iph->ttl = ttl; 1456 iph->protocol = sk->sk_protocol; 1457 ip_copy_addrs(iph, fl4); 1458 ip_select_ident(net, skb, sk); 1459 1460 if (opt) { 1461 iph->ihl += opt->optlen >> 2; 1462 ip_options_build(skb, opt, cork->addr, rt); 1463 } 1464 1465 skb->priority = cork->priority; 1466 skb->mark = cork->mark; 1467 if (sk_is_tcp(sk)) 1468 skb_set_delivery_time(skb, cork->transmit_time, SKB_CLOCK_MONOTONIC); 1469 else 1470 skb_set_delivery_type_by_clockid(skb, cork->transmit_time, sk->sk_clockid); 1471 /* 1472 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1473 * on dst refcount 1474 */ 1475 cork->dst = NULL; 1476 skb_dst_set(skb, &rt->dst); 1477 1478 if (iph->protocol == IPPROTO_ICMP) { 1479 u8 icmp_type; 1480 1481 /* For such sockets, transhdrlen is zero when do ip_append_data(), 1482 * so icmphdr does not in skb linear region and can not get icmp_type 1483 * by icmp_hdr(skb)->type. 1484 */ 1485 if (sk->sk_type == SOCK_RAW && 1486 !(fl4->flowi4_flags & FLOWI_FLAG_KNOWN_NH)) 1487 icmp_type = fl4->fl4_icmp_type; 1488 else 1489 icmp_type = icmp_hdr(skb)->type; 1490 icmp_out_count(net, icmp_type); 1491 } 1492 1493 ip_cork_release(cork); 1494 out: 1495 return skb; 1496 } 1497 1498 int ip_send_skb(struct net *net, struct sk_buff *skb) 1499 { 1500 int err; 1501 1502 err = ip_local_out(net, skb->sk, skb); 1503 if (err) { 1504 if (err > 0) 1505 err = net_xmit_errno(err); 1506 if (err) 1507 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1508 } 1509 1510 return err; 1511 } 1512 1513 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1514 { 1515 struct sk_buff *skb; 1516 1517 skb = ip_finish_skb(sk, fl4); 1518 if (!skb) 1519 return 0; 1520 1521 /* Netfilter gets whole the not fragmented skb. */ 1522 return ip_send_skb(sock_net(sk), skb); 1523 } 1524 1525 /* 1526 * Throw away all pending data on the socket. 1527 */ 1528 static void __ip_flush_pending_frames(struct sock *sk, 1529 struct sk_buff_head *queue, 1530 struct inet_cork *cork) 1531 { 1532 struct sk_buff *skb; 1533 1534 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1535 kfree_skb(skb); 1536 1537 ip_cork_release(cork); 1538 } 1539 1540 void ip_flush_pending_frames(struct sock *sk) 1541 { 1542 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1543 } 1544 1545 struct sk_buff *ip_make_skb(struct sock *sk, 1546 struct flowi4 *fl4, 1547 int getfrag(void *from, char *to, int offset, 1548 int len, int odd, struct sk_buff *skb), 1549 void *from, int length, int transhdrlen, 1550 struct ipcm_cookie *ipc, struct rtable **rtp, 1551 struct inet_cork *cork, unsigned int flags) 1552 { 1553 struct sk_buff_head queue; 1554 int err; 1555 1556 if (flags & MSG_PROBE) 1557 return NULL; 1558 1559 __skb_queue_head_init(&queue); 1560 1561 cork->flags = 0; 1562 cork->addr = 0; 1563 cork->opt = NULL; 1564 err = ip_setup_cork(sk, cork, ipc, rtp); 1565 if (err) 1566 return ERR_PTR(err); 1567 1568 err = __ip_append_data(sk, fl4, &queue, cork, 1569 ¤t->task_frag, getfrag, 1570 from, length, transhdrlen, flags); 1571 if (err) { 1572 __ip_flush_pending_frames(sk, &queue, cork); 1573 return ERR_PTR(err); 1574 } 1575 1576 return __ip_make_skb(sk, fl4, &queue, cork); 1577 } 1578 1579 /* 1580 * Fetch data from kernel space and fill in checksum if needed. 1581 */ 1582 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1583 int len, int odd, struct sk_buff *skb) 1584 { 1585 __wsum csum; 1586 1587 csum = csum_partial_copy_nocheck(dptr+offset, to, len); 1588 skb->csum = csum_block_add(skb->csum, csum, odd); 1589 return 0; 1590 } 1591 1592 /* 1593 * Generic function to send a packet as reply to another packet. 1594 * Used to send some TCP resets/acks so far. 1595 */ 1596 void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk, 1597 struct sk_buff *skb, 1598 const struct ip_options *sopt, 1599 __be32 daddr, __be32 saddr, 1600 const struct ip_reply_arg *arg, 1601 unsigned int len, u64 transmit_time, u32 txhash) 1602 { 1603 struct ip_options_data replyopts; 1604 struct ipcm_cookie ipc; 1605 struct flowi4 fl4; 1606 struct rtable *rt = skb_rtable(skb); 1607 struct net *net = sock_net(sk); 1608 struct sk_buff *nskb; 1609 int err; 1610 int oif; 1611 1612 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt)) 1613 return; 1614 1615 ipcm_init(&ipc); 1616 ipc.addr = daddr; 1617 ipc.sockc.transmit_time = transmit_time; 1618 1619 if (replyopts.opt.opt.optlen) { 1620 ipc.opt = &replyopts.opt; 1621 1622 if (replyopts.opt.opt.srr) 1623 daddr = replyopts.opt.opt.faddr; 1624 } 1625 1626 oif = arg->bound_dev_if; 1627 if (!oif && netif_index_is_l3_master(net, skb->skb_iif)) 1628 oif = skb->skb_iif; 1629 1630 flowi4_init_output(&fl4, oif, 1631 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark, 1632 arg->tos & INET_DSCP_MASK, 1633 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1634 ip_reply_arg_flowi_flags(arg), 1635 daddr, saddr, 1636 tcp_hdr(skb)->source, tcp_hdr(skb)->dest, 1637 arg->uid); 1638 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 1639 rt = ip_route_output_flow(net, &fl4, sk); 1640 if (IS_ERR(rt)) 1641 return; 1642 1643 inet_sk(sk)->tos = arg->tos; 1644 1645 sk->sk_protocol = ip_hdr(skb)->protocol; 1646 sk->sk_bound_dev_if = arg->bound_dev_if; 1647 sk->sk_sndbuf = READ_ONCE(sysctl_wmem_default); 1648 ipc.sockc.mark = fl4.flowi4_mark; 1649 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, 1650 len, 0, &ipc, &rt, MSG_DONTWAIT); 1651 if (unlikely(err)) { 1652 ip_flush_pending_frames(sk); 1653 goto out; 1654 } 1655 1656 nskb = skb_peek(&sk->sk_write_queue); 1657 if (nskb) { 1658 if (arg->csumoffset >= 0) 1659 *((__sum16 *)skb_transport_header(nskb) + 1660 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1661 arg->csum)); 1662 nskb->ip_summed = CHECKSUM_NONE; 1663 if (orig_sk) 1664 skb_set_owner_edemux(nskb, (struct sock *)orig_sk); 1665 if (transmit_time) 1666 nskb->tstamp_type = SKB_CLOCK_MONOTONIC; 1667 if (txhash) 1668 skb_set_hash(nskb, txhash, PKT_HASH_TYPE_L4); 1669 ip_push_pending_frames(sk, &fl4); 1670 } 1671 out: 1672 ip_rt_put(rt); 1673 } 1674 1675 void __init ip_init(void) 1676 { 1677 ip_rt_init(); 1678 inet_initpeers(); 1679 1680 #if defined(CONFIG_IP_MULTICAST) 1681 igmp_mc_init(); 1682 #endif 1683 } 1684