net/ipv4/inet_lro.c

   1 /*
   2  *  linux/net/ipv4/inet_lro.c
   3  *
   4  *  Large Receive Offload (ipv4 / tcp)
   5  *
   6  *  (C) Copyright IBM Corp. 2007
   7  *
   8  *  Authors:
   9  *       Jan-Bernd Themann <themann@de.ibm.com>
  10  *       Christoph Raisch <raisch@de.ibm.com>
  11  *
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2, or (at your option)
  16  * any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  26  */
  27
  28
  29 #include <linux/module.h>
  30 #include <linux/if_vlan.h>
  31 #include <linux/inet_lro.h>
  32
  33 MODULE_LICENSE("GPL");
  34 MODULE_AUTHOR("Jan-Bernd Themann <themann@de.ibm.com>");
  35 MODULE_DESCRIPTION("Large Receive Offload (ipv4 / tcp)");
  36
  37 #define TCP_HDR_LEN(tcph) (tcph->doff << 2)
  38 #define IP_HDR_LEN(iph) (iph->ihl << 2)
  39 #define TCP_PAYLOAD_LENGTH(iph, tcph) \
  40         (ntohs(iph->tot_len) - IP_HDR_LEN(iph) - TCP_HDR_LEN(tcph))
  41
  42 #define IPH_LEN_WO_OPTIONS 5
  43 #define TCPH_LEN_WO_OPTIONS 5
  44 #define TCPH_LEN_W_TIMESTAMP 8
  45
  46 #define LRO_MAX_PG_HLEN 64
  47
  48 #define LRO_INC_STATS(lro_mgr, attr) { lro_mgr->stats.attr++; }
  49
  50 /*
  51  * Basic tcp checks whether packet is suitable for LRO
  52  */
  53
  54 static int lro_tcp_ip_check(const struct iphdr *iph, const struct tcphdr *tcph,
  55                             int len, const struct net_lro_desc *lro_desc)
  56 {
  57         /* check ip header: don't aggregate padded frames */
  58         if (ntohs(iph->tot_len) != len)
  59                 return -1;
  60
  61         if (TCP_PAYLOAD_LENGTH(iph, tcph) == 0)
  62                 return -1;
  63
  64         if (iph->ihl != IPH_LEN_WO_OPTIONS)
  65                 return -1;
  66
  67         if (tcph->cwr || tcph->ece || tcph->urg || !tcph->ack ||
  68             tcph->rst || tcph->syn || tcph->fin)
  69                 return -1;
  70
  71         if (INET_ECN_is_ce(ipv4_get_dsfield(iph)))
  72                 return -1;
  73
  74         if (tcph->doff != TCPH_LEN_WO_OPTIONS &&
  75             tcph->doff != TCPH_LEN_W_TIMESTAMP)
  76                 return -1;
  77
  78         /* check tcp options (only timestamp allowed) */
  79         if (tcph->doff == TCPH_LEN_W_TIMESTAMP) {
  80                 __be32 *topt = (__be32 *)(tcph + 1);
  81
  82                 if (*topt != htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16)
  83                                    | (TCPOPT_TIMESTAMP << 8)
  84                                    | TCPOLEN_TIMESTAMP))
  85                         return -1;
  86
  87                 /* timestamp should be in right order */
  88                 topt++;
  89                 if (lro_desc && after(ntohl(lro_desc->tcp_rcv_tsval),
  90                                       ntohl(*topt)))
  91                         return -1;
  92
  93                 /* timestamp reply should not be zero */
  94                 topt++;
  95                 if (*topt == 0)
  96                         return -1;
  97         }
  98
  99         return 0;
 100 }
 101
 102 static void lro_update_tcp_ip_header(struct net_lro_desc *lro_desc)
 103 {
 104         struct iphdr *iph = lro_desc->iph;
 105         struct tcphdr *tcph = lro_desc->tcph;
 106         __be32 *p;
 107         __wsum tcp_hdr_csum;
 108
 109         tcph->ack_seq = lro_desc->tcp_ack;
 110         tcph->window = lro_desc->tcp_window;
 111
 112         if (lro_desc->tcp_saw_tstamp) {
 113                 p = (__be32 *)(tcph + 1);
 114                 *(p+2) = lro_desc->tcp_rcv_tsecr;
 115         }
 116
 117         iph->tot_len = htons(lro_desc->ip_tot_len);
 118
 119         iph->check = 0;
 120         iph->check = ip_fast_csum((u8 *)lro_desc->iph, iph->ihl);
 121
 122         tcph->check = 0;
 123         tcp_hdr_csum = csum_partial(tcph, TCP_HDR_LEN(tcph), 0);
 124         lro_desc->data_csum = csum_add(lro_desc->data_csum, tcp_hdr_csum);
 125         tcph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
 126                                         lro_desc->ip_tot_len -
 127                                         IP_HDR_LEN(iph), IPPROTO_TCP,
 128                                         lro_desc->data_csum);
 129 }
 130
 131 static __wsum lro_tcp_data_csum(struct iphdr *iph, struct tcphdr *tcph, int len)
 132 {
 133         __wsum tcp_csum;
 134         __wsum tcp_hdr_csum;
 135         __wsum tcp_ps_hdr_csum;
 136
 137         tcp_csum = ~csum_unfold(tcph->check);
 138         tcp_hdr_csum = csum_partial(tcph, TCP_HDR_LEN(tcph), tcp_csum);
 139
 140         tcp_ps_hdr_csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
 141                                              len + TCP_HDR_LEN(tcph),
 142                                              IPPROTO_TCP, 0);
 143
 144         return csum_sub(csum_sub(tcp_csum, tcp_hdr_csum),
 145                         tcp_ps_hdr_csum);
 146 }
 147
 148 static void lro_init_desc(struct net_lro_desc *lro_desc, struct sk_buff *skb,
 149                           struct iphdr *iph, struct tcphdr *tcph)
 150 {
 151         int nr_frags;
 152         __be32 *ptr;
 153         u32 tcp_data_len = TCP_PAYLOAD_LENGTH(iph, tcph);
 154
 155         nr_frags = skb_shinfo(skb)->nr_frags;
 156         lro_desc->parent = skb;
 157         lro_desc->next_frag = &(skb_shinfo(skb)->frags[nr_frags]);
 158         lro_desc->iph = iph;
 159         lro_desc->tcph = tcph;
 160         lro_desc->tcp_next_seq = ntohl(tcph->seq) + tcp_data_len;
 161         lro_desc->tcp_ack = tcph->ack_seq;
 162         lro_desc->tcp_window = tcph->window;
 163
 164         lro_desc->pkt_aggr_cnt = 1;
 165         lro_desc->ip_tot_len = ntohs(iph->tot_len);
 166
 167         if (tcph->doff == 8) {
 168                 ptr = (__be32 *)(tcph+1);
 169                 lro_desc->tcp_saw_tstamp = 1;
 170                 lro_desc->tcp_rcv_tsval = *(ptr+1);
 171                 lro_desc->tcp_rcv_tsecr = *(ptr+2);
 172         }
 173
 174         lro_desc->mss = tcp_data_len;
 175         lro_desc->active = 1;
 176
 177         lro_desc->data_csum = lro_tcp_data_csum(iph, tcph,
 178                                                 tcp_data_len);
 179 }
 180
 181 static inline void lro_clear_desc(struct net_lro_desc *lro_desc)
 182 {
 183         memset(lro_desc, 0, sizeof(struct net_lro_desc));
 184 }
 185
 186 static void lro_add_common(struct net_lro_desc *lro_desc, struct iphdr *iph,
 187                            struct tcphdr *tcph, int tcp_data_len)
 188 {
 189         struct sk_buff *parent = lro_desc->parent;
 190         __be32 *topt;
 191
 192         lro_desc->pkt_aggr_cnt++;
 193         lro_desc->ip_tot_len += tcp_data_len;
 194         lro_desc->tcp_next_seq += tcp_data_len;
 195         lro_desc->tcp_window = tcph->window;
 196         lro_desc->tcp_ack = tcph->ack_seq;
 197
 198         /* don't update tcp_rcv_tsval, would not work with PAWS */
 199         if (lro_desc->tcp_saw_tstamp) {
 200                 topt = (__be32 *) (tcph + 1);
 201                 lro_desc->tcp_rcv_tsecr = *(topt + 2);
 202         }
 203
 204         lro_desc->data_csum = csum_block_add(lro_desc->data_csum,
 205                                              lro_tcp_data_csum(iph, tcph,
 206                                                                tcp_data_len),
 207                                              parent->len);
 208
 209         parent->len += tcp_data_len;
 210         parent->data_len += tcp_data_len;
 211         if (tcp_data_len > lro_desc->mss)
 212                 lro_desc->mss = tcp_data_len;
 213 }
 214
 215 static void lro_add_packet(struct net_lro_desc *lro_desc, struct sk_buff *skb,
 216                            struct iphdr *iph, struct tcphdr *tcph)
 217 {
 218         struct sk_buff *parent = lro_desc->parent;
 219         int tcp_data_len = TCP_PAYLOAD_LENGTH(iph, tcph);
 220
 221         lro_add_common(lro_desc, iph, tcph, tcp_data_len);
 222
 223         skb_pull(skb, (skb->len - tcp_data_len));
 224         parent->truesize += skb->truesize;
 225
 226         if (lro_desc->last_skb)
 227                 lro_desc->last_skb->next = skb;
 228         else
 229                 skb_shinfo(parent)->frag_list = skb;
 230
 231         lro_desc->last_skb = skb;
 232 }
 233
 234 static void lro_add_frags(struct net_lro_desc *lro_desc,
 235                           int len, int hlen, int truesize,
 236                           struct skb_frag_struct *skb_frags,
 237                           struct iphdr *iph, struct tcphdr *tcph)
 238 {
 239         struct sk_buff *skb = lro_desc->parent;
 240         int tcp_data_len = TCP_PAYLOAD_LENGTH(iph, tcph);
 241
 242         lro_add_common(lro_desc, iph, tcph, tcp_data_len);
 243
 244         skb->truesize += truesize;
 245
 246         skb_frags[0].page_offset += hlen;
 247         skb_frag_size_sub(&skb_frags[0], hlen);
 248
 249         while (tcp_data_len > 0) {
 250                 *(lro_desc->next_frag) = *skb_frags;
 251                 tcp_data_len -= skb_frag_size(skb_frags);
 252                 lro_desc->next_frag++;
 253                 skb_frags++;
 254                 skb_shinfo(skb)->nr_frags++;
 255         }
 256 }
 257
 258 static int lro_check_tcp_conn(struct net_lro_desc *lro_desc,
 259                               struct iphdr *iph,
 260                               struct tcphdr *tcph)
 261 {
 262         if ((lro_desc->iph->saddr != iph->saddr) ||
 263             (lro_desc->iph->daddr != iph->daddr) ||
 264             (lro_desc->tcph->source != tcph->source) ||
 265             (lro_desc->tcph->dest != tcph->dest))
 266                 return -1;
 267         return 0;
 268 }
 269
 270 static struct net_lro_desc *lro_get_desc(struct net_lro_mgr *lro_mgr,
 271                                          struct net_lro_desc *lro_arr,
 272                                          struct iphdr *iph,
 273                                          struct tcphdr *tcph)
 274 {
 275         struct net_lro_desc *lro_desc = NULL;
 276         struct net_lro_desc *tmp;
 277         int max_desc = lro_mgr->max_desc;
 278         int i;
 279
 280         for (i = 0; i < max_desc; i++) {
 281                 tmp = &lro_arr[i];
 282                 if (tmp->active)
 283                         if (!lro_check_tcp_conn(tmp, iph, tcph)) {
 284                                 lro_desc = tmp;
 285                                 goto out;
 286                         }
 287         }
 288
 289         for (i = 0; i < max_desc; i++) {
 290                 if (!lro_arr[i].active) {
 291                         lro_desc = &lro_arr[i];
 292                         goto out;
 293                 }
 294         }
 295
 296         LRO_INC_STATS(lro_mgr, no_desc);
 297 out:
 298         return lro_desc;
 299 }
 300
 301 static void lro_flush(struct net_lro_mgr *lro_mgr,
 302                       struct net_lro_desc *lro_desc)
 303 {
 304         if (lro_desc->pkt_aggr_cnt > 1)
 305                 lro_update_tcp_ip_header(lro_desc);
 306
 307         skb_shinfo(lro_desc->parent)->gso_size = lro_desc->mss;
 308
 309         if (lro_mgr->features & LRO_F_NAPI)
 310                 netif_receive_skb(lro_desc->parent);
 311         else
 312                 netif_rx(lro_desc->parent);
 313
 314         LRO_INC_STATS(lro_mgr, flushed);
 315         lro_clear_desc(lro_desc);
 316 }
 317
 318 static int __lro_proc_skb(struct net_lro_mgr *lro_mgr, struct sk_buff *skb,
 319                           void *priv)
 320 {
 321         struct net_lro_desc *lro_desc;
 322         struct iphdr *iph;
 323         struct tcphdr *tcph;
 324         u64 flags;
 325         int vlan_hdr_len = 0;
 326
 327         if (!lro_mgr->get_skb_header ||
 328             lro_mgr->get_skb_header(skb, (void *)&iph, (void *)&tcph,
 329                                     &flags, priv))
 330                 goto out;
 331
 332         if (!(flags & LRO_IPV4) || !(flags & LRO_TCP))
 333                 goto out;
 334
 335         lro_desc = lro_get_desc(lro_mgr, lro_mgr->lro_arr, iph, tcph);
 336         if (!lro_desc)
 337                 goto out;
 338
 339         if ((skb->protocol == htons(ETH_P_8021Q)) &&
 340             !(lro_mgr->features & LRO_F_EXTRACT_VLAN_ID))
 341                 vlan_hdr_len = VLAN_HLEN;
 342
 343         if (!lro_desc->active) { /* start new lro session */
 344                 if (lro_tcp_ip_check(iph, tcph, skb->len - vlan_hdr_len, NULL))
 345                         goto out;
 346
 347                 skb->ip_summed = lro_mgr->ip_summed_aggr;
 348                 lro_init_desc(lro_desc, skb, iph, tcph);
 349                 LRO_INC_STATS(lro_mgr, aggregated);
 350                 return 0;
 351         }
 352
 353         if (lro_desc->tcp_next_seq != ntohl(tcph->seq))
 354                 goto out2;
 355
 356         if (lro_tcp_ip_check(iph, tcph, skb->len, lro_desc))
 357                 goto out2;
 358
 359         lro_add_packet(lro_desc, skb, iph, tcph);
 360         LRO_INC_STATS(lro_mgr, aggregated);
 361
 362         if ((lro_desc->pkt_aggr_cnt >= lro_mgr->max_aggr) ||
 363             lro_desc->parent->len > (0xFFFF - lro_mgr->dev->mtu))
 364                 lro_flush(lro_mgr, lro_desc);
 365
 366         return 0;
 367
 368 out2: /* send aggregated SKBs to stack */
 369         lro_flush(lro_mgr, lro_desc);
 370
 371 out:
 372         return 1;
 373 }
 374
 375
 376 static struct sk_buff *lro_gen_skb(struct net_lro_mgr *lro_mgr,
 377                                    struct skb_frag_struct *frags,
 378                                    int len, int true_size,
 379                                    void *mac_hdr,
 380                                    int hlen, __wsum sum,
 381                                    u32 ip_summed)
 382 {
 383         struct sk_buff *skb;
 384         struct skb_frag_struct *skb_frags;
 385         int data_len = len;
 386         int hdr_len = min(len, hlen);
 387
 388         skb = netdev_alloc_skb(lro_mgr->dev, hlen + lro_mgr->frag_align_pad);
 389         if (!skb)
 390                 return NULL;
 391
 392         skb_reserve(skb, lro_mgr->frag_align_pad);
 393         skb->len = len;
 394         skb->data_len = len - hdr_len;
 395         skb->truesize += true_size;
 396         skb->tail += hdr_len;
 397
 398         memcpy(skb->data, mac_hdr, hdr_len);
 399
 400         skb_frags = skb_shinfo(skb)->frags;
 401         while (data_len > 0) {
 402                 *skb_frags = *frags;
 403                 data_len -= skb_frag_size(frags);
 404                 skb_frags++;
 405                 frags++;
 406                 skb_shinfo(skb)->nr_frags++;
 407         }
 408
 409         skb_shinfo(skb)->frags[0].page_offset += hdr_len;
 410         skb_frag_size_sub(&skb_shinfo(skb)->frags[0], hdr_len);
 411
 412         skb->ip_summed = ip_summed;
 413         skb->csum = sum;
 414         skb->protocol = eth_type_trans(skb, lro_mgr->dev);
 415         return skb;
 416 }
 417
 418 static struct sk_buff *__lro_proc_segment(struct net_lro_mgr *lro_mgr,
 419                                           struct skb_frag_struct *frags,
 420                                           int len, int true_size,
 421                                           void *priv, __wsum sum)
 422 {
 423         struct net_lro_desc *lro_desc;
 424         struct iphdr *iph;
 425         struct tcphdr *tcph;
 426         struct sk_buff *skb;
 427         u64 flags;
 428         void *mac_hdr;
 429         int mac_hdr_len;
 430         int hdr_len = LRO_MAX_PG_HLEN;
 431         int vlan_hdr_len = 0;
 432
 433         if (!lro_mgr->get_frag_header ||
 434             lro_mgr->get_frag_header(frags, (void *)&mac_hdr, (void *)&iph,
 435                                      (void *)&tcph, &flags, priv)) {
 436                 mac_hdr = skb_frag_address(frags);
 437                 goto out1;
 438         }
 439
 440         if (!(flags & LRO_IPV4) || !(flags & LRO_TCP))
 441                 goto out1;
 442
 443         hdr_len = (int)((void *)(tcph) + TCP_HDR_LEN(tcph) - mac_hdr);
 444         mac_hdr_len = (int)((void *)(iph) - mac_hdr);
 445
 446         lro_desc = lro_get_desc(lro_mgr, lro_mgr->lro_arr, iph, tcph);
 447         if (!lro_desc)
 448                 goto out1;
 449
 450         if (!lro_desc->active) { /* start new lro session */
 451                 if (lro_tcp_ip_check(iph, tcph, len - mac_hdr_len, NULL))
 452                         goto out1;
 453
 454                 skb = lro_gen_skb(lro_mgr, frags, len, true_size, mac_hdr,
 455                                   hdr_len, 0, lro_mgr->ip_summed_aggr);
 456                 if (!skb)
 457                         goto out;
 458
 459                 if ((skb->protocol == htons(ETH_P_8021Q)) &&
 460                     !(lro_mgr->features & LRO_F_EXTRACT_VLAN_ID))
 461                         vlan_hdr_len = VLAN_HLEN;
 462
 463                 iph = (void *)(skb->data + vlan_hdr_len);
 464                 tcph = (void *)((u8 *)skb->data + vlan_hdr_len
 465                                 + IP_HDR_LEN(iph));
 466
 467                 lro_init_desc(lro_desc, skb, iph, tcph);
 468                 LRO_INC_STATS(lro_mgr, aggregated);
 469                 return NULL;
 470         }
 471
 472         if (lro_desc->tcp_next_seq != ntohl(tcph->seq))
 473                 goto out2;
 474
 475         if (lro_tcp_ip_check(iph, tcph, len - mac_hdr_len, lro_desc))
 476                 goto out2;
 477
 478         lro_add_frags(lro_desc, len, hdr_len, true_size, frags, iph, tcph);
 479         LRO_INC_STATS(lro_mgr, aggregated);
 480
 481         if ((skb_shinfo(lro_desc->parent)->nr_frags >= lro_mgr->max_aggr) ||
 482             lro_desc->parent->len > (0xFFFF - lro_mgr->dev->mtu))
 483                 lro_flush(lro_mgr, lro_desc);
 484
 485         return NULL;
 486
 487 out2: /* send aggregated packets to the stack */
 488         lro_flush(lro_mgr, lro_desc);
 489
 490 out1:  /* Original packet has to be posted to the stack */
 491         skb = lro_gen_skb(lro_mgr, frags, len, true_size, mac_hdr,
 492                           hdr_len, sum, lro_mgr->ip_summed);
 493 out:
 494         return skb;
 495 }
 496
 497 void lro_receive_skb(struct net_lro_mgr *lro_mgr,
 498                      struct sk_buff *skb,
 499                      void *priv)
 500 {
 501         if (__lro_proc_skb(lro_mgr, skb, priv)) {
 502                 if (lro_mgr->features & LRO_F_NAPI)
 503                         netif_receive_skb(skb);
 504                 else
 505                         netif_rx(skb);
 506         }
 507 }
 508 EXPORT_SYMBOL(lro_receive_skb);
 509
 510 void lro_receive_frags(struct net_lro_mgr *lro_mgr,
 511                        struct skb_frag_struct *frags,
 512                        int len, int true_size, void *priv, __wsum sum)
 513 {
 514         struct sk_buff *skb;
 515
 516         skb = __lro_proc_segment(lro_mgr, frags, len, true_size, priv, sum);
 517         if (!skb)
 518                 return;
 519
 520         if (lro_mgr->features & LRO_F_NAPI)
 521                 netif_receive_skb(skb);
 522         else
 523                 netif_rx(skb);
 524 }
 525 EXPORT_SYMBOL(lro_receive_frags);
 526
 527 void lro_flush_all(struct net_lro_mgr *lro_mgr)
 528 {
 529         int i;
 530         struct net_lro_desc *lro_desc = lro_mgr->lro_arr;
 531
 532         for (i = 0; i < lro_mgr->max_desc; i++) {
 533                 if (lro_desc[i].active)
 534                         lro_flush(lro_mgr, &lro_desc[i]);
 535         }
 536 }
 537 EXPORT_SYMBOL(lro_flush_all);
 538
 539 void lro_flush_pkt(struct net_lro_mgr *lro_mgr,
 540                   struct iphdr *iph, struct tcphdr *tcph)
 541 {
 542         struct net_lro_desc *lro_desc;
 543
 544         lro_desc = lro_get_desc(lro_mgr, lro_mgr->lro_arr, iph, tcph);
 545         if (lro_desc->active)
 546                 lro_flush(lro_mgr, lro_desc);
 547 }
 548 EXPORT_SYMBOL(lro_flush_pkt);