1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * IPV4 GSO/GRO offload support 4 * Linux INET implementation 5 * 6 * TCPv4 GSO/GRO support 7 */ 8 9 #include <linux/indirect_call_wrapper.h> 10 #include <linux/skbuff.h> 11 #include <net/gro.h> 12 #include <net/gso.h> 13 #include <net/tcp.h> 14 #include <net/protocol.h> 15 16 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, 17 unsigned int seq, unsigned int mss) 18 { 19 while (skb) { 20 if (before(ts_seq, seq + mss)) { 21 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP; 22 skb_shinfo(skb)->tskey = ts_seq; 23 return; 24 } 25 26 skb = skb->next; 27 seq += mss; 28 } 29 } 30 31 static void __tcpv4_gso_segment_csum(struct sk_buff *seg, 32 __be32 *oldip, __be32 newip, 33 __be16 *oldport, __be16 newport) 34 { 35 struct tcphdr *th; 36 struct iphdr *iph; 37 38 if (*oldip == newip && *oldport == newport) 39 return; 40 41 th = tcp_hdr(seg); 42 iph = ip_hdr(seg); 43 44 inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true); 45 inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false); 46 *oldport = newport; 47 48 csum_replace4(&iph->check, *oldip, newip); 49 *oldip = newip; 50 } 51 52 static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs) 53 { 54 const struct tcphdr *th; 55 const struct iphdr *iph; 56 struct sk_buff *seg; 57 struct tcphdr *th2; 58 struct iphdr *iph2; 59 60 seg = segs; 61 th = tcp_hdr(seg); 62 iph = ip_hdr(seg); 63 th2 = tcp_hdr(seg->next); 64 iph2 = ip_hdr(seg->next); 65 66 if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) && 67 iph->daddr == iph2->daddr && iph->saddr == iph2->saddr) 68 return segs; 69 70 while ((seg = seg->next)) { 71 th2 = tcp_hdr(seg); 72 iph2 = ip_hdr(seg); 73 74 __tcpv4_gso_segment_csum(seg, 75 &iph2->saddr, iph->saddr, 76 &th2->source, th->source); 77 __tcpv4_gso_segment_csum(seg, 78 &iph2->daddr, iph->daddr, 79 &th2->dest, th->dest); 80 } 81 82 return segs; 83 } 84 85 static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb, 86 netdev_features_t features) 87 { 88 skb = skb_segment_list(skb, features, skb_mac_header_len(skb)); 89 if (IS_ERR(skb)) 90 return skb; 91 92 return __tcpv4_gso_segment_list_csum(skb); 93 } 94 95 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, 96 netdev_features_t features) 97 { 98 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)) 99 return ERR_PTR(-EINVAL); 100 101 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 102 return ERR_PTR(-EINVAL); 103 104 if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) 105 return __tcp4_gso_segment_list(skb, features); 106 107 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) { 108 const struct iphdr *iph = ip_hdr(skb); 109 struct tcphdr *th = tcp_hdr(skb); 110 111 /* Set up checksum pseudo header, usually expect stack to 112 * have done this already. 113 */ 114 115 th->check = 0; 116 skb->ip_summed = CHECKSUM_PARTIAL; 117 __tcp_v4_send_check(skb, iph->saddr, iph->daddr); 118 } 119 120 return tcp_gso_segment(skb, features); 121 } 122 123 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 124 netdev_features_t features) 125 { 126 struct sk_buff *segs = ERR_PTR(-EINVAL); 127 unsigned int sum_truesize = 0; 128 struct tcphdr *th; 129 unsigned int thlen; 130 unsigned int seq; 131 unsigned int oldlen; 132 unsigned int mss; 133 struct sk_buff *gso_skb = skb; 134 __sum16 newcheck; 135 bool ooo_okay, copy_destructor; 136 __wsum delta; 137 138 th = tcp_hdr(skb); 139 thlen = th->doff * 4; 140 if (thlen < sizeof(*th)) 141 goto out; 142 143 if (unlikely(skb_checksum_start(skb) != skb_transport_header(skb))) 144 goto out; 145 146 if (!pskb_may_pull(skb, thlen)) 147 goto out; 148 149 oldlen = ~skb->len; 150 __skb_pull(skb, thlen); 151 152 mss = skb_shinfo(skb)->gso_size; 153 if (unlikely(skb->len <= mss)) 154 goto out; 155 156 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 157 /* Packet is from an untrusted source, reset gso_segs. */ 158 159 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss); 160 161 segs = NULL; 162 goto out; 163 } 164 165 copy_destructor = gso_skb->destructor == tcp_wfree; 166 ooo_okay = gso_skb->ooo_okay; 167 /* All segments but the first should have ooo_okay cleared */ 168 skb->ooo_okay = 0; 169 170 segs = skb_segment(skb, features); 171 if (IS_ERR(segs)) 172 goto out; 173 174 /* Only first segment might have ooo_okay set */ 175 segs->ooo_okay = ooo_okay; 176 177 /* GSO partial and frag_list segmentation only requires splitting 178 * the frame into an MSS multiple and possibly a remainder, both 179 * cases return a GSO skb. So update the mss now. 180 */ 181 if (skb_is_gso(segs)) 182 mss *= skb_shinfo(segs)->gso_segs; 183 184 delta = (__force __wsum)htonl(oldlen + thlen + mss); 185 186 skb = segs; 187 th = tcp_hdr(skb); 188 seq = ntohl(th->seq); 189 190 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP)) 191 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss); 192 193 newcheck = ~csum_fold(csum_add(csum_unfold(th->check), delta)); 194 195 while (skb->next) { 196 th->fin = th->psh = 0; 197 th->check = newcheck; 198 199 if (skb->ip_summed == CHECKSUM_PARTIAL) 200 gso_reset_checksum(skb, ~th->check); 201 else 202 th->check = gso_make_checksum(skb, ~th->check); 203 204 seq += mss; 205 if (copy_destructor) { 206 skb->destructor = gso_skb->destructor; 207 skb->sk = gso_skb->sk; 208 sum_truesize += skb->truesize; 209 } 210 skb = skb->next; 211 th = tcp_hdr(skb); 212 213 th->seq = htonl(seq); 214 th->cwr = 0; 215 } 216 217 /* Following permits TCP Small Queues to work well with GSO : 218 * The callback to TCP stack will be called at the time last frag 219 * is freed at TX completion, and not right now when gso_skb 220 * is freed by GSO engine 221 */ 222 if (copy_destructor) { 223 int delta; 224 225 swap(gso_skb->sk, skb->sk); 226 swap(gso_skb->destructor, skb->destructor); 227 sum_truesize += skb->truesize; 228 delta = sum_truesize - gso_skb->truesize; 229 /* In some pathological cases, delta can be negative. 230 * We need to either use refcount_add() or refcount_sub_and_test() 231 */ 232 if (likely(delta >= 0)) 233 refcount_add(delta, &skb->sk->sk_wmem_alloc); 234 else 235 WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc)); 236 } 237 238 delta = (__force __wsum)htonl(oldlen + 239 (skb_tail_pointer(skb) - 240 skb_transport_header(skb)) + 241 skb->data_len); 242 th->check = ~csum_fold(csum_add(csum_unfold(th->check), delta)); 243 if (skb->ip_summed == CHECKSUM_PARTIAL) 244 gso_reset_checksum(skb, ~th->check); 245 else 246 th->check = gso_make_checksum(skb, ~th->check); 247 out: 248 return segs; 249 } 250 251 struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th) 252 { 253 struct tcphdr *th2; 254 struct sk_buff *p; 255 256 list_for_each_entry(p, head, list) { 257 if (!NAPI_GRO_CB(p)->same_flow) 258 continue; 259 260 th2 = tcp_hdr(p); 261 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) { 262 NAPI_GRO_CB(p)->same_flow = 0; 263 continue; 264 } 265 266 return p; 267 } 268 269 return NULL; 270 } 271 272 struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb) 273 { 274 unsigned int thlen, hlen, off; 275 struct tcphdr *th; 276 277 off = skb_gro_offset(skb); 278 hlen = off + sizeof(*th); 279 th = skb_gro_header(skb, hlen, off); 280 if (unlikely(!th)) 281 return NULL; 282 283 thlen = th->doff * 4; 284 if (thlen < sizeof(*th)) 285 return NULL; 286 287 hlen = off + thlen; 288 if (!skb_gro_may_pull(skb, hlen)) { 289 th = skb_gro_header_slow(skb, hlen, off); 290 if (unlikely(!th)) 291 return NULL; 292 } 293 294 skb_gro_pull(skb, thlen); 295 296 return th; 297 } 298 299 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb, 300 struct tcphdr *th) 301 { 302 unsigned int thlen = th->doff * 4; 303 struct sk_buff *pp = NULL; 304 struct sk_buff *p; 305 struct tcphdr *th2; 306 unsigned int len; 307 __be32 flags; 308 unsigned int mss = 1; 309 int flush = 1; 310 int i; 311 312 len = skb_gro_len(skb); 313 flags = tcp_flag_word(th); 314 315 p = tcp_gro_lookup(head, th); 316 if (!p) 317 goto out_check_final; 318 319 th2 = tcp_hdr(p); 320 flush = (__force int)(flags & TCP_FLAG_CWR); 321 flush |= (__force int)((flags ^ tcp_flag_word(th2)) & 322 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); 323 flush |= (__force int)(th->ack_seq ^ th2->ack_seq); 324 for (i = sizeof(*th); i < thlen; i += 4) 325 flush |= *(u32 *)((u8 *)th + i) ^ 326 *(u32 *)((u8 *)th2 + i); 327 328 flush |= gro_receive_network_flush(th, th2, p); 329 330 mss = skb_shinfo(p)->gso_size; 331 332 /* If skb is a GRO packet, make sure its gso_size matches prior packet mss. 333 * If it is a single frame, do not aggregate it if its length 334 * is bigger than our mss. 335 */ 336 if (unlikely(skb_is_gso(skb))) 337 flush |= (mss != skb_shinfo(skb)->gso_size); 338 else 339 flush |= (len - 1) >= mss; 340 341 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq); 342 flush |= skb_cmp_decrypted(p, skb); 343 344 if (unlikely(NAPI_GRO_CB(p)->is_flist)) { 345 flush |= (__force int)(flags ^ tcp_flag_word(th2)); 346 flush |= skb->ip_summed != p->ip_summed; 347 flush |= skb->csum_level != p->csum_level; 348 flush |= NAPI_GRO_CB(p)->count >= 64; 349 350 if (flush || skb_gro_receive_list(p, skb)) 351 mss = 1; 352 353 goto out_check_final; 354 } 355 356 if (flush || skb_gro_receive(p, skb)) { 357 mss = 1; 358 goto out_check_final; 359 } 360 361 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH); 362 363 out_check_final: 364 /* Force a flush if last segment is smaller than mss. */ 365 if (unlikely(skb_is_gso(skb))) 366 flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size; 367 else 368 flush = len < mss; 369 370 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH | 371 TCP_FLAG_RST | TCP_FLAG_SYN | 372 TCP_FLAG_FIN)); 373 374 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush)) 375 pp = p; 376 377 NAPI_GRO_CB(skb)->flush |= (flush != 0); 378 379 return pp; 380 } 381 382 void tcp_gro_complete(struct sk_buff *skb) 383 { 384 struct tcphdr *th = tcp_hdr(skb); 385 struct skb_shared_info *shinfo; 386 387 if (skb->encapsulation) 388 skb->inner_transport_header = skb->transport_header; 389 390 skb->csum_start = (unsigned char *)th - skb->head; 391 skb->csum_offset = offsetof(struct tcphdr, check); 392 skb->ip_summed = CHECKSUM_PARTIAL; 393 394 shinfo = skb_shinfo(skb); 395 shinfo->gso_segs = NAPI_GRO_CB(skb)->count; 396 397 if (th->cwr) 398 shinfo->gso_type |= SKB_GSO_TCP_ECN; 399 } 400 EXPORT_SYMBOL(tcp_gro_complete); 401 402 static void tcp4_check_fraglist_gro(struct list_head *head, struct sk_buff *skb, 403 struct tcphdr *th) 404 { 405 const struct iphdr *iph; 406 struct sk_buff *p; 407 struct sock *sk; 408 struct net *net; 409 int iif, sdif; 410 411 if (likely(!(skb->dev->features & NETIF_F_GRO_FRAGLIST))) 412 return; 413 414 p = tcp_gro_lookup(head, th); 415 if (p) { 416 NAPI_GRO_CB(skb)->is_flist = NAPI_GRO_CB(p)->is_flist; 417 return; 418 } 419 420 inet_get_iif_sdif(skb, &iif, &sdif); 421 iph = skb_gro_network_header(skb); 422 net = dev_net(skb->dev); 423 sk = __inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo, 424 iph->saddr, th->source, 425 iph->daddr, ntohs(th->dest), 426 iif, sdif); 427 NAPI_GRO_CB(skb)->is_flist = !sk; 428 if (sk) 429 sock_put(sk); 430 } 431 432 INDIRECT_CALLABLE_SCOPE 433 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb) 434 { 435 struct tcphdr *th; 436 437 /* Don't bother verifying checksum if we're going to flush anyway. */ 438 if (!NAPI_GRO_CB(skb)->flush && 439 skb_gro_checksum_validate(skb, IPPROTO_TCP, 440 inet_gro_compute_pseudo)) 441 goto flush; 442 443 th = tcp_gro_pull_header(skb); 444 if (!th) 445 goto flush; 446 447 tcp4_check_fraglist_gro(head, skb, th); 448 449 return tcp_gro_receive(head, skb, th); 450 451 flush: 452 NAPI_GRO_CB(skb)->flush = 1; 453 return NULL; 454 } 455 456 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff) 457 { 458 const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation]; 459 const struct iphdr *iph = (struct iphdr *)(skb->data + offset); 460 struct tcphdr *th = tcp_hdr(skb); 461 462 if (unlikely(NAPI_GRO_CB(skb)->is_flist)) { 463 skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV4; 464 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count; 465 466 __skb_incr_checksum_unnecessary(skb); 467 468 return 0; 469 } 470 471 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr, 472 iph->daddr, 0); 473 474 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4 | 475 (NAPI_GRO_CB(skb)->ip_fixedid * SKB_GSO_TCP_FIXEDID); 476 477 tcp_gro_complete(skb); 478 return 0; 479 } 480 481 int __init tcpv4_offload_init(void) 482 { 483 net_hotdata.tcpv4_offload = (struct net_offload) { 484 .callbacks = { 485 .gso_segment = tcp4_gso_segment, 486 .gro_receive = tcp4_gro_receive, 487 .gro_complete = tcp4_gro_complete, 488 }, 489 }; 490 return inet_add_offload(&net_hotdata.tcpv4_offload, IPPROTO_TCP); 491 } 492