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