1 /* 2 * IPV4 GSO/GRO offload support 3 * Linux INET implementation 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 * 10 * UDPv4 GSO support 11 */ 12 13 #include <linux/skbuff.h> 14 #include <net/udp.h> 15 #include <net/protocol.h> 16 #include <net/inet_common.h> 17 18 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb, 19 netdev_features_t features, 20 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 21 netdev_features_t features), 22 __be16 new_protocol, bool is_ipv6) 23 { 24 int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb); 25 bool remcsum, need_csum, offload_csum, gso_partial; 26 struct sk_buff *segs = ERR_PTR(-EINVAL); 27 struct udphdr *uh = udp_hdr(skb); 28 u16 mac_offset = skb->mac_header; 29 __be16 protocol = skb->protocol; 30 u16 mac_len = skb->mac_len; 31 int udp_offset, outer_hlen; 32 __wsum partial; 33 bool need_ipsec; 34 35 if (unlikely(!pskb_may_pull(skb, tnl_hlen))) 36 goto out; 37 38 /* Adjust partial header checksum to negate old length. 39 * We cannot rely on the value contained in uh->len as it is 40 * possible that the actual value exceeds the boundaries of the 41 * 16 bit length field due to the header being added outside of an 42 * IP or IPv6 frame that was already limited to 64K - 1. 43 */ 44 if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL) 45 partial = (__force __wsum)uh->len; 46 else 47 partial = (__force __wsum)htonl(skb->len); 48 partial = csum_sub(csum_unfold(uh->check), partial); 49 50 /* setup inner skb. */ 51 skb->encapsulation = 0; 52 SKB_GSO_CB(skb)->encap_level = 0; 53 __skb_pull(skb, tnl_hlen); 54 skb_reset_mac_header(skb); 55 skb_set_network_header(skb, skb_inner_network_offset(skb)); 56 skb->mac_len = skb_inner_network_offset(skb); 57 skb->protocol = new_protocol; 58 59 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM); 60 skb->encap_hdr_csum = need_csum; 61 62 remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM); 63 skb->remcsum_offload = remcsum; 64 65 need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb)); 66 /* Try to offload checksum if possible */ 67 offload_csum = !!(need_csum && 68 !need_ipsec && 69 (skb->dev->features & 70 (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) : 71 (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM)))); 72 73 features &= skb->dev->hw_enc_features; 74 75 /* The only checksum offload we care about from here on out is the 76 * outer one so strip the existing checksum feature flags and 77 * instead set the flag based on our outer checksum offload value. 78 */ 79 if (remcsum) { 80 features &= ~NETIF_F_CSUM_MASK; 81 if (!need_csum || offload_csum) 82 features |= NETIF_F_HW_CSUM; 83 } 84 85 /* segment inner packet. */ 86 segs = gso_inner_segment(skb, features); 87 if (IS_ERR_OR_NULL(segs)) { 88 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, 89 mac_len); 90 goto out; 91 } 92 93 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL); 94 95 outer_hlen = skb_tnl_header_len(skb); 96 udp_offset = outer_hlen - tnl_hlen; 97 skb = segs; 98 do { 99 unsigned int len; 100 101 if (remcsum) 102 skb->ip_summed = CHECKSUM_NONE; 103 104 /* Set up inner headers if we are offloading inner checksum */ 105 if (skb->ip_summed == CHECKSUM_PARTIAL) { 106 skb_reset_inner_headers(skb); 107 skb->encapsulation = 1; 108 } 109 110 skb->mac_len = mac_len; 111 skb->protocol = protocol; 112 113 __skb_push(skb, outer_hlen); 114 skb_reset_mac_header(skb); 115 skb_set_network_header(skb, mac_len); 116 skb_set_transport_header(skb, udp_offset); 117 len = skb->len - udp_offset; 118 uh = udp_hdr(skb); 119 120 /* If we are only performing partial GSO the inner header 121 * will be using a length value equal to only one MSS sized 122 * segment instead of the entire frame. 123 */ 124 if (gso_partial && skb_is_gso(skb)) { 125 uh->len = htons(skb_shinfo(skb)->gso_size + 126 SKB_GSO_CB(skb)->data_offset + 127 skb->head - (unsigned char *)uh); 128 } else { 129 uh->len = htons(len); 130 } 131 132 if (!need_csum) 133 continue; 134 135 uh->check = ~csum_fold(csum_add(partial, 136 (__force __wsum)htonl(len))); 137 138 if (skb->encapsulation || !offload_csum) { 139 uh->check = gso_make_checksum(skb, ~uh->check); 140 if (uh->check == 0) 141 uh->check = CSUM_MANGLED_0; 142 } else { 143 skb->ip_summed = CHECKSUM_PARTIAL; 144 skb->csum_start = skb_transport_header(skb) - skb->head; 145 skb->csum_offset = offsetof(struct udphdr, check); 146 } 147 } while ((skb = skb->next)); 148 out: 149 return segs; 150 } 151 152 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, 153 netdev_features_t features, 154 bool is_ipv6) 155 { 156 __be16 protocol = skb->protocol; 157 const struct net_offload **offloads; 158 const struct net_offload *ops; 159 struct sk_buff *segs = ERR_PTR(-EINVAL); 160 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 161 netdev_features_t features); 162 163 rcu_read_lock(); 164 165 switch (skb->inner_protocol_type) { 166 case ENCAP_TYPE_ETHER: 167 protocol = skb->inner_protocol; 168 gso_inner_segment = skb_mac_gso_segment; 169 break; 170 case ENCAP_TYPE_IPPROTO: 171 offloads = is_ipv6 ? inet6_offloads : inet_offloads; 172 ops = rcu_dereference(offloads[skb->inner_ipproto]); 173 if (!ops || !ops->callbacks.gso_segment) 174 goto out_unlock; 175 gso_inner_segment = ops->callbacks.gso_segment; 176 break; 177 default: 178 goto out_unlock; 179 } 180 181 segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment, 182 protocol, is_ipv6); 183 184 out_unlock: 185 rcu_read_unlock(); 186 187 return segs; 188 } 189 EXPORT_SYMBOL(skb_udp_tunnel_segment); 190 191 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, 192 netdev_features_t features) 193 { 194 struct sock *sk = gso_skb->sk; 195 unsigned int sum_truesize = 0; 196 struct sk_buff *segs, *seg; 197 struct udphdr *uh; 198 unsigned int mss; 199 bool copy_dtor; 200 __sum16 check; 201 __be16 newlen; 202 203 mss = skb_shinfo(gso_skb)->gso_size; 204 if (gso_skb->len <= sizeof(*uh) + mss) 205 return ERR_PTR(-EINVAL); 206 207 skb_pull(gso_skb, sizeof(*uh)); 208 209 /* clear destructor to avoid skb_segment assigning it to tail */ 210 copy_dtor = gso_skb->destructor == sock_wfree; 211 if (copy_dtor) 212 gso_skb->destructor = NULL; 213 214 segs = skb_segment(gso_skb, features); 215 if (unlikely(IS_ERR_OR_NULL(segs))) { 216 if (copy_dtor) 217 gso_skb->destructor = sock_wfree; 218 return segs; 219 } 220 221 /* GSO partial and frag_list segmentation only requires splitting 222 * the frame into an MSS multiple and possibly a remainder, both 223 * cases return a GSO skb. So update the mss now. 224 */ 225 if (skb_is_gso(segs)) 226 mss *= skb_shinfo(segs)->gso_segs; 227 228 seg = segs; 229 uh = udp_hdr(seg); 230 231 /* compute checksum adjustment based on old length versus new */ 232 newlen = htons(sizeof(*uh) + mss); 233 check = csum16_add(csum16_sub(uh->check, uh->len), newlen); 234 235 for (;;) { 236 if (copy_dtor) { 237 seg->destructor = sock_wfree; 238 seg->sk = sk; 239 sum_truesize += seg->truesize; 240 } 241 242 if (!seg->next) 243 break; 244 245 uh->len = newlen; 246 uh->check = check; 247 248 if (seg->ip_summed == CHECKSUM_PARTIAL) 249 gso_reset_checksum(seg, ~check); 250 else 251 uh->check = gso_make_checksum(seg, ~check) ? : 252 CSUM_MANGLED_0; 253 254 seg = seg->next; 255 uh = udp_hdr(seg); 256 } 257 258 /* last packet can be partial gso_size, account for that in checksum */ 259 newlen = htons(skb_tail_pointer(seg) - skb_transport_header(seg) + 260 seg->data_len); 261 check = csum16_add(csum16_sub(uh->check, uh->len), newlen); 262 263 uh->len = newlen; 264 uh->check = check; 265 266 if (seg->ip_summed == CHECKSUM_PARTIAL) 267 gso_reset_checksum(seg, ~check); 268 else 269 uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0; 270 271 /* update refcount for the packet */ 272 if (copy_dtor) { 273 int delta = sum_truesize - gso_skb->truesize; 274 275 /* In some pathological cases, delta can be negative. 276 * We need to either use refcount_add() or refcount_sub_and_test() 277 */ 278 if (likely(delta >= 0)) 279 refcount_add(delta, &sk->sk_wmem_alloc); 280 else 281 WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc)); 282 } 283 return segs; 284 } 285 EXPORT_SYMBOL_GPL(__udp_gso_segment); 286 287 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 288 netdev_features_t features) 289 { 290 struct sk_buff *segs = ERR_PTR(-EINVAL); 291 unsigned int mss; 292 __wsum csum; 293 struct udphdr *uh; 294 struct iphdr *iph; 295 296 if (skb->encapsulation && 297 (skb_shinfo(skb)->gso_type & 298 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) { 299 segs = skb_udp_tunnel_segment(skb, features, false); 300 goto out; 301 } 302 303 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4))) 304 goto out; 305 306 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 307 goto out; 308 309 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) 310 return __udp_gso_segment(skb, features); 311 312 mss = skb_shinfo(skb)->gso_size; 313 if (unlikely(skb->len <= mss)) 314 goto out; 315 316 /* Do software UFO. Complete and fill in the UDP checksum as 317 * HW cannot do checksum of UDP packets sent as multiple 318 * IP fragments. 319 */ 320 321 uh = udp_hdr(skb); 322 iph = ip_hdr(skb); 323 324 uh->check = 0; 325 csum = skb_checksum(skb, 0, skb->len, 0); 326 uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum); 327 if (uh->check == 0) 328 uh->check = CSUM_MANGLED_0; 329 330 skb->ip_summed = CHECKSUM_UNNECESSARY; 331 332 /* If there is no outer header we can fake a checksum offload 333 * due to the fact that we have already done the checksum in 334 * software prior to segmenting the frame. 335 */ 336 if (!skb->encap_hdr_csum) 337 features |= NETIF_F_HW_CSUM; 338 339 /* Fragment the skb. IP headers of the fragments are updated in 340 * inet_gso_segment() 341 */ 342 segs = skb_segment(skb, features); 343 out: 344 return segs; 345 } 346 347 #define UDP_GRO_CNT_MAX 64 348 static struct sk_buff *udp_gro_receive_segment(struct list_head *head, 349 struct sk_buff *skb) 350 { 351 struct udphdr *uh = udp_hdr(skb); 352 struct sk_buff *pp = NULL; 353 struct udphdr *uh2; 354 struct sk_buff *p; 355 356 /* requires non zero csum, for symmetry with GSO */ 357 if (!uh->check) { 358 NAPI_GRO_CB(skb)->flush = 1; 359 return NULL; 360 } 361 362 /* pull encapsulating udp header */ 363 skb_gro_pull(skb, sizeof(struct udphdr)); 364 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 365 366 list_for_each_entry(p, head, list) { 367 if (!NAPI_GRO_CB(p)->same_flow) 368 continue; 369 370 uh2 = udp_hdr(p); 371 372 /* Match ports only, as csum is always non zero */ 373 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) { 374 NAPI_GRO_CB(p)->same_flow = 0; 375 continue; 376 } 377 378 /* Terminate the flow on len mismatch or if it grow "too much". 379 * Under small packet flood GRO count could elsewhere grow a lot 380 * leading to execessive truesize values 381 */ 382 if (!skb_gro_receive(p, skb) && 383 NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX) 384 pp = p; 385 else if (uh->len != uh2->len) 386 pp = p; 387 388 return pp; 389 } 390 391 /* mismatch, but we never need to flush */ 392 return NULL; 393 } 394 395 INDIRECT_CALLABLE_DECLARE(struct sock *udp6_lib_lookup_skb(struct sk_buff *skb, 396 __be16 sport, __be16 dport)); 397 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb, 398 struct udphdr *uh, udp_lookup_t lookup) 399 { 400 struct sk_buff *pp = NULL; 401 struct sk_buff *p; 402 struct udphdr *uh2; 403 unsigned int off = skb_gro_offset(skb); 404 int flush = 1; 405 struct sock *sk; 406 407 rcu_read_lock(); 408 sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb, 409 udp4_lib_lookup_skb, skb, uh->source, uh->dest); 410 if (!sk) 411 goto out_unlock; 412 413 if (udp_sk(sk)->gro_enabled) { 414 pp = call_gro_receive(udp_gro_receive_segment, head, skb); 415 rcu_read_unlock(); 416 return pp; 417 } 418 419 if (NAPI_GRO_CB(skb)->encap_mark || 420 (skb->ip_summed != CHECKSUM_PARTIAL && 421 NAPI_GRO_CB(skb)->csum_cnt == 0 && 422 !NAPI_GRO_CB(skb)->csum_valid) || 423 !udp_sk(sk)->gro_receive) 424 goto out_unlock; 425 426 /* mark that this skb passed once through the tunnel gro layer */ 427 NAPI_GRO_CB(skb)->encap_mark = 1; 428 429 flush = 0; 430 431 list_for_each_entry(p, head, list) { 432 if (!NAPI_GRO_CB(p)->same_flow) 433 continue; 434 435 uh2 = (struct udphdr *)(p->data + off); 436 437 /* Match ports and either checksums are either both zero 438 * or nonzero. 439 */ 440 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) || 441 (!uh->check ^ !uh2->check)) { 442 NAPI_GRO_CB(p)->same_flow = 0; 443 continue; 444 } 445 } 446 447 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ 448 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 449 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); 450 451 out_unlock: 452 rcu_read_unlock(); 453 skb_gro_flush_final(skb, pp, flush); 454 return pp; 455 } 456 EXPORT_SYMBOL(udp_gro_receive); 457 458 INDIRECT_CALLABLE_SCOPE 459 struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb) 460 { 461 struct udphdr *uh = udp_gro_udphdr(skb); 462 463 if (unlikely(!uh) || !static_branch_unlikely(&udp_encap_needed_key)) 464 goto flush; 465 466 /* Don't bother verifying checksum if we're going to flush anyway. */ 467 if (NAPI_GRO_CB(skb)->flush) 468 goto skip; 469 470 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 471 inet_gro_compute_pseudo)) 472 goto flush; 473 else if (uh->check) 474 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 475 inet_gro_compute_pseudo); 476 skip: 477 NAPI_GRO_CB(skb)->is_ipv6 = 0; 478 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb); 479 480 flush: 481 NAPI_GRO_CB(skb)->flush = 1; 482 return NULL; 483 } 484 485 static int udp_gro_complete_segment(struct sk_buff *skb) 486 { 487 struct udphdr *uh = udp_hdr(skb); 488 489 skb->csum_start = (unsigned char *)uh - skb->head; 490 skb->csum_offset = offsetof(struct udphdr, check); 491 skb->ip_summed = CHECKSUM_PARTIAL; 492 493 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 494 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4; 495 return 0; 496 } 497 498 int udp_gro_complete(struct sk_buff *skb, int nhoff, 499 udp_lookup_t lookup) 500 { 501 __be16 newlen = htons(skb->len - nhoff); 502 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 503 int err = -ENOSYS; 504 struct sock *sk; 505 506 uh->len = newlen; 507 508 rcu_read_lock(); 509 sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb, 510 udp4_lib_lookup_skb, skb, uh->source, uh->dest); 511 if (sk && udp_sk(sk)->gro_enabled) { 512 err = udp_gro_complete_segment(skb); 513 } else if (sk && udp_sk(sk)->gro_complete) { 514 skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM 515 : SKB_GSO_UDP_TUNNEL; 516 517 /* Set encapsulation before calling into inner gro_complete() 518 * functions to make them set up the inner offsets. 519 */ 520 skb->encapsulation = 1; 521 err = udp_sk(sk)->gro_complete(sk, skb, 522 nhoff + sizeof(struct udphdr)); 523 } 524 rcu_read_unlock(); 525 526 if (skb->remcsum_offload) 527 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM; 528 529 return err; 530 } 531 EXPORT_SYMBOL(udp_gro_complete); 532 533 INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff) 534 { 535 const struct iphdr *iph = ip_hdr(skb); 536 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 537 538 if (uh->check) 539 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr, 540 iph->daddr, 0); 541 542 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb); 543 } 544 545 static const struct net_offload udpv4_offload = { 546 .callbacks = { 547 .gso_segment = udp4_ufo_fragment, 548 .gro_receive = udp4_gro_receive, 549 .gro_complete = udp4_gro_complete, 550 }, 551 }; 552 553 int __init udpv4_offload_init(void) 554 { 555 return inet_add_offload(&udpv4_offload, IPPROTO_UDP); 556 } 557