1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * IPV4 GSO/GRO offload support 4 * Linux INET implementation 5 * 6 * UDPv4 GSO support 7 */ 8 9 #include <linux/skbuff.h> 10 #include <net/udp.h> 11 #include <net/protocol.h> 12 #include <net/inet_common.h> 13 14 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb, 15 netdev_features_t features, 16 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 17 netdev_features_t features), 18 __be16 new_protocol, bool is_ipv6) 19 { 20 int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb); 21 bool remcsum, need_csum, offload_csum, gso_partial; 22 struct sk_buff *segs = ERR_PTR(-EINVAL); 23 struct udphdr *uh = udp_hdr(skb); 24 u16 mac_offset = skb->mac_header; 25 __be16 protocol = skb->protocol; 26 u16 mac_len = skb->mac_len; 27 int udp_offset, outer_hlen; 28 __wsum partial; 29 bool need_ipsec; 30 31 if (unlikely(!pskb_may_pull(skb, tnl_hlen))) 32 goto out; 33 34 /* Adjust partial header checksum to negate old length. 35 * We cannot rely on the value contained in uh->len as it is 36 * possible that the actual value exceeds the boundaries of the 37 * 16 bit length field due to the header being added outside of an 38 * IP or IPv6 frame that was already limited to 64K - 1. 39 */ 40 if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL) 41 partial = (__force __wsum)uh->len; 42 else 43 partial = (__force __wsum)htonl(skb->len); 44 partial = csum_sub(csum_unfold(uh->check), partial); 45 46 /* setup inner skb. */ 47 skb->encapsulation = 0; 48 SKB_GSO_CB(skb)->encap_level = 0; 49 __skb_pull(skb, tnl_hlen); 50 skb_reset_mac_header(skb); 51 skb_set_network_header(skb, skb_inner_network_offset(skb)); 52 skb->mac_len = skb_inner_network_offset(skb); 53 skb->protocol = new_protocol; 54 55 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM); 56 skb->encap_hdr_csum = need_csum; 57 58 remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM); 59 skb->remcsum_offload = remcsum; 60 61 need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb)); 62 /* Try to offload checksum if possible */ 63 offload_csum = !!(need_csum && 64 !need_ipsec && 65 (skb->dev->features & 66 (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) : 67 (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM)))); 68 69 features &= skb->dev->hw_enc_features; 70 71 /* The only checksum offload we care about from here on out is the 72 * outer one so strip the existing checksum feature flags and 73 * instead set the flag based on our outer checksum offload value. 74 */ 75 if (remcsum) { 76 features &= ~NETIF_F_CSUM_MASK; 77 if (!need_csum || offload_csum) 78 features |= NETIF_F_HW_CSUM; 79 } 80 81 /* segment inner packet. */ 82 segs = gso_inner_segment(skb, features); 83 if (IS_ERR_OR_NULL(segs)) { 84 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, 85 mac_len); 86 goto out; 87 } 88 89 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL); 90 91 outer_hlen = skb_tnl_header_len(skb); 92 udp_offset = outer_hlen - tnl_hlen; 93 skb = segs; 94 do { 95 unsigned int len; 96 97 if (remcsum) 98 skb->ip_summed = CHECKSUM_NONE; 99 100 /* Set up inner headers if we are offloading inner checksum */ 101 if (skb->ip_summed == CHECKSUM_PARTIAL) { 102 skb_reset_inner_headers(skb); 103 skb->encapsulation = 1; 104 } 105 106 skb->mac_len = mac_len; 107 skb->protocol = protocol; 108 109 __skb_push(skb, outer_hlen); 110 skb_reset_mac_header(skb); 111 skb_set_network_header(skb, mac_len); 112 skb_set_transport_header(skb, udp_offset); 113 len = skb->len - udp_offset; 114 uh = udp_hdr(skb); 115 116 /* If we are only performing partial GSO the inner header 117 * will be using a length value equal to only one MSS sized 118 * segment instead of the entire frame. 119 */ 120 if (gso_partial && skb_is_gso(skb)) { 121 uh->len = htons(skb_shinfo(skb)->gso_size + 122 SKB_GSO_CB(skb)->data_offset + 123 skb->head - (unsigned char *)uh); 124 } else { 125 uh->len = htons(len); 126 } 127 128 if (!need_csum) 129 continue; 130 131 uh->check = ~csum_fold(csum_add(partial, 132 (__force __wsum)htonl(len))); 133 134 if (skb->encapsulation || !offload_csum) { 135 uh->check = gso_make_checksum(skb, ~uh->check); 136 if (uh->check == 0) 137 uh->check = CSUM_MANGLED_0; 138 } else { 139 skb->ip_summed = CHECKSUM_PARTIAL; 140 skb->csum_start = skb_transport_header(skb) - skb->head; 141 skb->csum_offset = offsetof(struct udphdr, check); 142 } 143 } while ((skb = skb->next)); 144 out: 145 return segs; 146 } 147 148 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, 149 netdev_features_t features, 150 bool is_ipv6) 151 { 152 __be16 protocol = skb->protocol; 153 const struct net_offload **offloads; 154 const struct net_offload *ops; 155 struct sk_buff *segs = ERR_PTR(-EINVAL); 156 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb, 157 netdev_features_t features); 158 159 rcu_read_lock(); 160 161 switch (skb->inner_protocol_type) { 162 case ENCAP_TYPE_ETHER: 163 protocol = skb->inner_protocol; 164 gso_inner_segment = skb_mac_gso_segment; 165 break; 166 case ENCAP_TYPE_IPPROTO: 167 offloads = is_ipv6 ? inet6_offloads : inet_offloads; 168 ops = rcu_dereference(offloads[skb->inner_ipproto]); 169 if (!ops || !ops->callbacks.gso_segment) 170 goto out_unlock; 171 gso_inner_segment = ops->callbacks.gso_segment; 172 break; 173 default: 174 goto out_unlock; 175 } 176 177 segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment, 178 protocol, is_ipv6); 179 180 out_unlock: 181 rcu_read_unlock(); 182 183 return segs; 184 } 185 EXPORT_SYMBOL(skb_udp_tunnel_segment); 186 187 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, 188 netdev_features_t features) 189 { 190 struct sock *sk = gso_skb->sk; 191 unsigned int sum_truesize = 0; 192 struct sk_buff *segs, *seg; 193 struct udphdr *uh; 194 unsigned int mss; 195 bool copy_dtor; 196 __sum16 check; 197 __be16 newlen; 198 199 mss = skb_shinfo(gso_skb)->gso_size; 200 if (gso_skb->len <= sizeof(*uh) + mss) 201 return ERR_PTR(-EINVAL); 202 203 skb_pull(gso_skb, sizeof(*uh)); 204 205 /* clear destructor to avoid skb_segment assigning it to tail */ 206 copy_dtor = gso_skb->destructor == sock_wfree; 207 if (copy_dtor) 208 gso_skb->destructor = NULL; 209 210 segs = skb_segment(gso_skb, features); 211 if (unlikely(IS_ERR_OR_NULL(segs))) { 212 if (copy_dtor) 213 gso_skb->destructor = sock_wfree; 214 return segs; 215 } 216 217 /* GSO partial and frag_list segmentation only requires splitting 218 * the frame into an MSS multiple and possibly a remainder, both 219 * cases return a GSO skb. So update the mss now. 220 */ 221 if (skb_is_gso(segs)) 222 mss *= skb_shinfo(segs)->gso_segs; 223 224 seg = segs; 225 uh = udp_hdr(seg); 226 227 /* compute checksum adjustment based on old length versus new */ 228 newlen = htons(sizeof(*uh) + mss); 229 check = csum16_add(csum16_sub(uh->check, uh->len), newlen); 230 231 for (;;) { 232 if (copy_dtor) { 233 seg->destructor = sock_wfree; 234 seg->sk = sk; 235 sum_truesize += seg->truesize; 236 } 237 238 if (!seg->next) 239 break; 240 241 uh->len = newlen; 242 uh->check = check; 243 244 if (seg->ip_summed == CHECKSUM_PARTIAL) 245 gso_reset_checksum(seg, ~check); 246 else 247 uh->check = gso_make_checksum(seg, ~check) ? : 248 CSUM_MANGLED_0; 249 250 seg = seg->next; 251 uh = udp_hdr(seg); 252 } 253 254 /* last packet can be partial gso_size, account for that in checksum */ 255 newlen = htons(skb_tail_pointer(seg) - skb_transport_header(seg) + 256 seg->data_len); 257 check = csum16_add(csum16_sub(uh->check, uh->len), newlen); 258 259 uh->len = newlen; 260 uh->check = check; 261 262 if (seg->ip_summed == CHECKSUM_PARTIAL) 263 gso_reset_checksum(seg, ~check); 264 else 265 uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0; 266 267 /* update refcount for the packet */ 268 if (copy_dtor) { 269 int delta = sum_truesize - gso_skb->truesize; 270 271 /* In some pathological cases, delta can be negative. 272 * We need to either use refcount_add() or refcount_sub_and_test() 273 */ 274 if (likely(delta >= 0)) 275 refcount_add(delta, &sk->sk_wmem_alloc); 276 else 277 WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc)); 278 } 279 return segs; 280 } 281 EXPORT_SYMBOL_GPL(__udp_gso_segment); 282 283 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 284 netdev_features_t features) 285 { 286 struct sk_buff *segs = ERR_PTR(-EINVAL); 287 unsigned int mss; 288 __wsum csum; 289 struct udphdr *uh; 290 struct iphdr *iph; 291 292 if (skb->encapsulation && 293 (skb_shinfo(skb)->gso_type & 294 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) { 295 segs = skb_udp_tunnel_segment(skb, features, false); 296 goto out; 297 } 298 299 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4))) 300 goto out; 301 302 if (!pskb_may_pull(skb, sizeof(struct udphdr))) 303 goto out; 304 305 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) 306 return __udp_gso_segment(skb, features); 307 308 mss = skb_shinfo(skb)->gso_size; 309 if (unlikely(skb->len <= mss)) 310 goto out; 311 312 /* Do software UFO. Complete and fill in the UDP checksum as 313 * HW cannot do checksum of UDP packets sent as multiple 314 * IP fragments. 315 */ 316 317 uh = udp_hdr(skb); 318 iph = ip_hdr(skb); 319 320 uh->check = 0; 321 csum = skb_checksum(skb, 0, skb->len, 0); 322 uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum); 323 if (uh->check == 0) 324 uh->check = CSUM_MANGLED_0; 325 326 skb->ip_summed = CHECKSUM_UNNECESSARY; 327 328 /* If there is no outer header we can fake a checksum offload 329 * due to the fact that we have already done the checksum in 330 * software prior to segmenting the frame. 331 */ 332 if (!skb->encap_hdr_csum) 333 features |= NETIF_F_HW_CSUM; 334 335 /* Fragment the skb. IP headers of the fragments are updated in 336 * inet_gso_segment() 337 */ 338 segs = skb_segment(skb, features); 339 out: 340 return segs; 341 } 342 343 #define UDP_GRO_CNT_MAX 64 344 static struct sk_buff *udp_gro_receive_segment(struct list_head *head, 345 struct sk_buff *skb) 346 { 347 struct udphdr *uh = udp_hdr(skb); 348 struct sk_buff *pp = NULL; 349 struct udphdr *uh2; 350 struct sk_buff *p; 351 unsigned int ulen; 352 353 /* requires non zero csum, for symmetry with GSO */ 354 if (!uh->check) { 355 NAPI_GRO_CB(skb)->flush = 1; 356 return NULL; 357 } 358 359 /* Do not deal with padded or malicious packets, sorry ! */ 360 ulen = ntohs(uh->len); 361 if (ulen <= sizeof(*uh) || ulen != skb_gro_len(skb)) { 362 NAPI_GRO_CB(skb)->flush = 1; 363 return NULL; 364 } 365 /* pull encapsulating udp header */ 366 skb_gro_pull(skb, sizeof(struct udphdr)); 367 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 368 369 list_for_each_entry(p, head, list) { 370 if (!NAPI_GRO_CB(p)->same_flow) 371 continue; 372 373 uh2 = udp_hdr(p); 374 375 /* Match ports only, as csum is always non zero */ 376 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) { 377 NAPI_GRO_CB(p)->same_flow = 0; 378 continue; 379 } 380 381 /* Terminate the flow on len mismatch or if it grow "too much". 382 * Under small packet flood GRO count could elsewhere grow a lot 383 * leading to excessive truesize values. 384 * On len mismatch merge the first packet shorter than gso_size, 385 * otherwise complete the GRO packet. 386 */ 387 if (ulen > ntohs(uh2->len) || skb_gro_receive(p, skb) || 388 ulen != ntohs(uh2->len) || 389 NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX) 390 pp = p; 391 392 return pp; 393 } 394 395 /* mismatch, but we never need to flush */ 396 return NULL; 397 } 398 399 INDIRECT_CALLABLE_DECLARE(struct sock *udp6_lib_lookup_skb(struct sk_buff *skb, 400 __be16 sport, __be16 dport)); 401 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb, 402 struct udphdr *uh, udp_lookup_t lookup) 403 { 404 struct sk_buff *pp = NULL; 405 struct sk_buff *p; 406 struct udphdr *uh2; 407 unsigned int off = skb_gro_offset(skb); 408 int flush = 1; 409 struct sock *sk; 410 411 rcu_read_lock(); 412 sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb, 413 udp4_lib_lookup_skb, skb, uh->source, uh->dest); 414 if (!sk) 415 goto out_unlock; 416 417 if (udp_sk(sk)->gro_enabled) { 418 pp = call_gro_receive(udp_gro_receive_segment, head, skb); 419 rcu_read_unlock(); 420 return pp; 421 } 422 423 if (NAPI_GRO_CB(skb)->encap_mark || 424 (skb->ip_summed != CHECKSUM_PARTIAL && 425 NAPI_GRO_CB(skb)->csum_cnt == 0 && 426 !NAPI_GRO_CB(skb)->csum_valid) || 427 !udp_sk(sk)->gro_receive) 428 goto out_unlock; 429 430 /* mark that this skb passed once through the tunnel gro layer */ 431 NAPI_GRO_CB(skb)->encap_mark = 1; 432 433 flush = 0; 434 435 list_for_each_entry(p, head, list) { 436 if (!NAPI_GRO_CB(p)->same_flow) 437 continue; 438 439 uh2 = (struct udphdr *)(p->data + off); 440 441 /* Match ports and either checksums are either both zero 442 * or nonzero. 443 */ 444 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) || 445 (!uh->check ^ !uh2->check)) { 446 NAPI_GRO_CB(p)->same_flow = 0; 447 continue; 448 } 449 } 450 451 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ 452 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); 453 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); 454 455 out_unlock: 456 rcu_read_unlock(); 457 skb_gro_flush_final(skb, pp, flush); 458 return pp; 459 } 460 EXPORT_SYMBOL(udp_gro_receive); 461 462 INDIRECT_CALLABLE_SCOPE 463 struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb) 464 { 465 struct udphdr *uh = udp_gro_udphdr(skb); 466 467 if (unlikely(!uh) || !static_branch_unlikely(&udp_encap_needed_key)) 468 goto flush; 469 470 /* Don't bother verifying checksum if we're going to flush anyway. */ 471 if (NAPI_GRO_CB(skb)->flush) 472 goto skip; 473 474 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check, 475 inet_gro_compute_pseudo)) 476 goto flush; 477 else if (uh->check) 478 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check, 479 inet_gro_compute_pseudo); 480 skip: 481 NAPI_GRO_CB(skb)->is_ipv6 = 0; 482 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb); 483 484 flush: 485 NAPI_GRO_CB(skb)->flush = 1; 486 return NULL; 487 } 488 489 static int udp_gro_complete_segment(struct sk_buff *skb) 490 { 491 struct udphdr *uh = udp_hdr(skb); 492 493 skb->csum_start = (unsigned char *)uh - skb->head; 494 skb->csum_offset = offsetof(struct udphdr, check); 495 skb->ip_summed = CHECKSUM_PARTIAL; 496 497 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 498 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4; 499 return 0; 500 } 501 502 int udp_gro_complete(struct sk_buff *skb, int nhoff, 503 udp_lookup_t lookup) 504 { 505 __be16 newlen = htons(skb->len - nhoff); 506 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 507 int err = -ENOSYS; 508 struct sock *sk; 509 510 uh->len = newlen; 511 512 rcu_read_lock(); 513 sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb, 514 udp4_lib_lookup_skb, skb, uh->source, uh->dest); 515 if (sk && udp_sk(sk)->gro_enabled) { 516 err = udp_gro_complete_segment(skb); 517 } else if (sk && udp_sk(sk)->gro_complete) { 518 skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM 519 : SKB_GSO_UDP_TUNNEL; 520 521 /* Set encapsulation before calling into inner gro_complete() 522 * functions to make them set up the inner offsets. 523 */ 524 skb->encapsulation = 1; 525 err = udp_sk(sk)->gro_complete(sk, skb, 526 nhoff + sizeof(struct udphdr)); 527 } 528 rcu_read_unlock(); 529 530 if (skb->remcsum_offload) 531 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM; 532 533 return err; 534 } 535 EXPORT_SYMBOL(udp_gro_complete); 536 537 INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff) 538 { 539 const struct iphdr *iph = ip_hdr(skb); 540 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff); 541 542 if (uh->check) 543 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr, 544 iph->daddr, 0); 545 546 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb); 547 } 548 549 static const struct net_offload udpv4_offload = { 550 .callbacks = { 551 .gso_segment = udp4_ufo_fragment, 552 .gro_receive = udp4_gro_receive, 553 .gro_complete = udp4_gro_complete, 554 }, 555 }; 556 557 int __init udpv4_offload_init(void) 558 { 559 return inet_add_offload(&udpv4_offload, IPPROTO_UDP); 560 } 561