1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * net/sched/sch_netem.c Network emulator 4 * 5 * Many of the algorithms and ideas for this came from 6 * NIST Net which is not copyrighted. 7 * 8 * Authors: Stephen Hemminger <shemminger@osdl.org> 9 * Catalin(ux aka Dino) BOIE <catab at umbrella dot ro> 10 */ 11 12 #include <linux/mm.h> 13 #include <linux/module.h> 14 #include <linux/slab.h> 15 #include <linux/types.h> 16 #include <linux/kernel.h> 17 #include <linux/errno.h> 18 #include <linux/skbuff.h> 19 #include <linux/vmalloc.h> 20 #include <linux/rtnetlink.h> 21 #include <linux/reciprocal_div.h> 22 #include <linux/rbtree.h> 23 24 #include <net/netlink.h> 25 #include <net/pkt_sched.h> 26 #include <net/inet_ecn.h> 27 28 #define VERSION "1.3" 29 30 /* Network Emulation Queuing algorithm. 31 ==================================== 32 33 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based 34 Network Emulation Tool 35 [2] Luigi Rizzo, DummyNet for FreeBSD 36 37 ---------------------------------------------------------------- 38 39 This started out as a simple way to delay outgoing packets to 40 test TCP but has grown to include most of the functionality 41 of a full blown network emulator like NISTnet. It can delay 42 packets and add random jitter (and correlation). The random 43 distribution can be loaded from a table as well to provide 44 normal, Pareto, or experimental curves. Packet loss, 45 duplication, and reordering can also be emulated. 46 47 This qdisc does not do classification that can be handled in 48 layering other disciplines. It does not need to do bandwidth 49 control either since that can be handled by using token 50 bucket or other rate control. 51 52 Correlated Loss Generator models 53 54 Added generation of correlated loss according to the 55 "Gilbert-Elliot" model, a 4-state markov model. 56 57 References: 58 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG 59 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general 60 and intuitive loss model for packet networks and its implementation 61 in the Netem module in the Linux kernel", available in [1] 62 63 Authors: Stefano Salsano <stefano.salsano at uniroma2.it 64 Fabio Ludovici <fabio.ludovici at yahoo.it> 65 */ 66 67 struct disttable { 68 u32 size; 69 s16 table[0]; 70 }; 71 72 struct netem_sched_data { 73 /* internal t(ime)fifo qdisc uses t_root and sch->limit */ 74 struct rb_root t_root; 75 76 /* a linear queue; reduces rbtree rebalancing when jitter is low */ 77 struct sk_buff *t_head; 78 struct sk_buff *t_tail; 79 80 /* optional qdisc for classful handling (NULL at netem init) */ 81 struct Qdisc *qdisc; 82 83 struct qdisc_watchdog watchdog; 84 85 s64 latency; 86 s64 jitter; 87 88 u32 loss; 89 u32 ecn; 90 u32 limit; 91 u32 counter; 92 u32 gap; 93 u32 duplicate; 94 u32 reorder; 95 u32 corrupt; 96 u64 rate; 97 s32 packet_overhead; 98 u32 cell_size; 99 struct reciprocal_value cell_size_reciprocal; 100 s32 cell_overhead; 101 102 struct crndstate { 103 u32 last; 104 u32 rho; 105 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor; 106 107 struct disttable *delay_dist; 108 109 enum { 110 CLG_RANDOM, 111 CLG_4_STATES, 112 CLG_GILB_ELL, 113 } loss_model; 114 115 enum { 116 TX_IN_GAP_PERIOD = 1, 117 TX_IN_BURST_PERIOD, 118 LOST_IN_GAP_PERIOD, 119 LOST_IN_BURST_PERIOD, 120 } _4_state_model; 121 122 enum { 123 GOOD_STATE = 1, 124 BAD_STATE, 125 } GE_state_model; 126 127 /* Correlated Loss Generation models */ 128 struct clgstate { 129 /* state of the Markov chain */ 130 u8 state; 131 132 /* 4-states and Gilbert-Elliot models */ 133 u32 a1; /* p13 for 4-states or p for GE */ 134 u32 a2; /* p31 for 4-states or r for GE */ 135 u32 a3; /* p32 for 4-states or h for GE */ 136 u32 a4; /* p14 for 4-states or 1-k for GE */ 137 u32 a5; /* p23 used only in 4-states */ 138 } clg; 139 140 struct tc_netem_slot slot_config; 141 struct slotstate { 142 u64 slot_next; 143 s32 packets_left; 144 s32 bytes_left; 145 } slot; 146 147 struct disttable *slot_dist; 148 }; 149 150 /* Time stamp put into socket buffer control block 151 * Only valid when skbs are in our internal t(ime)fifo queue. 152 * 153 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp, 154 * and skb->next & skb->prev are scratch space for a qdisc, 155 * we save skb->tstamp value in skb->cb[] before destroying it. 156 */ 157 struct netem_skb_cb { 158 u64 time_to_send; 159 }; 160 161 static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb) 162 { 163 /* we assume we can use skb next/prev/tstamp as storage for rb_node */ 164 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb)); 165 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data; 166 } 167 168 /* init_crandom - initialize correlated random number generator 169 * Use entropy source for initial seed. 170 */ 171 static void init_crandom(struct crndstate *state, unsigned long rho) 172 { 173 state->rho = rho; 174 state->last = prandom_u32(); 175 } 176 177 /* get_crandom - correlated random number generator 178 * Next number depends on last value. 179 * rho is scaled to avoid floating point. 180 */ 181 static u32 get_crandom(struct crndstate *state) 182 { 183 u64 value, rho; 184 unsigned long answer; 185 186 if (!state || state->rho == 0) /* no correlation */ 187 return prandom_u32(); 188 189 value = prandom_u32(); 190 rho = (u64)state->rho + 1; 191 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32; 192 state->last = answer; 193 return answer; 194 } 195 196 /* loss_4state - 4-state model loss generator 197 * Generates losses according to the 4-state Markov chain adopted in 198 * the GI (General and Intuitive) loss model. 199 */ 200 static bool loss_4state(struct netem_sched_data *q) 201 { 202 struct clgstate *clg = &q->clg; 203 u32 rnd = prandom_u32(); 204 205 /* 206 * Makes a comparison between rnd and the transition 207 * probabilities outgoing from the current state, then decides the 208 * next state and if the next packet has to be transmitted or lost. 209 * The four states correspond to: 210 * TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period 211 * LOST_IN_BURST_PERIOD => isolated losses within a gap period 212 * LOST_IN_GAP_PERIOD => lost packets within a burst period 213 * TX_IN_GAP_PERIOD => successfully transmitted packets within a burst period 214 */ 215 switch (clg->state) { 216 case TX_IN_GAP_PERIOD: 217 if (rnd < clg->a4) { 218 clg->state = LOST_IN_BURST_PERIOD; 219 return true; 220 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) { 221 clg->state = LOST_IN_GAP_PERIOD; 222 return true; 223 } else if (clg->a1 + clg->a4 < rnd) { 224 clg->state = TX_IN_GAP_PERIOD; 225 } 226 227 break; 228 case TX_IN_BURST_PERIOD: 229 if (rnd < clg->a5) { 230 clg->state = LOST_IN_GAP_PERIOD; 231 return true; 232 } else { 233 clg->state = TX_IN_BURST_PERIOD; 234 } 235 236 break; 237 case LOST_IN_GAP_PERIOD: 238 if (rnd < clg->a3) 239 clg->state = TX_IN_BURST_PERIOD; 240 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) { 241 clg->state = TX_IN_GAP_PERIOD; 242 } else if (clg->a2 + clg->a3 < rnd) { 243 clg->state = LOST_IN_GAP_PERIOD; 244 return true; 245 } 246 break; 247 case LOST_IN_BURST_PERIOD: 248 clg->state = TX_IN_GAP_PERIOD; 249 break; 250 } 251 252 return false; 253 } 254 255 /* loss_gilb_ell - Gilbert-Elliot model loss generator 256 * Generates losses according to the Gilbert-Elliot loss model or 257 * its special cases (Gilbert or Simple Gilbert) 258 * 259 * Makes a comparison between random number and the transition 260 * probabilities outgoing from the current state, then decides the 261 * next state. A second random number is extracted and the comparison 262 * with the loss probability of the current state decides if the next 263 * packet will be transmitted or lost. 264 */ 265 static bool loss_gilb_ell(struct netem_sched_data *q) 266 { 267 struct clgstate *clg = &q->clg; 268 269 switch (clg->state) { 270 case GOOD_STATE: 271 if (prandom_u32() < clg->a1) 272 clg->state = BAD_STATE; 273 if (prandom_u32() < clg->a4) 274 return true; 275 break; 276 case BAD_STATE: 277 if (prandom_u32() < clg->a2) 278 clg->state = GOOD_STATE; 279 if (prandom_u32() > clg->a3) 280 return true; 281 } 282 283 return false; 284 } 285 286 static bool loss_event(struct netem_sched_data *q) 287 { 288 switch (q->loss_model) { 289 case CLG_RANDOM: 290 /* Random packet drop 0 => none, ~0 => all */ 291 return q->loss && q->loss >= get_crandom(&q->loss_cor); 292 293 case CLG_4_STATES: 294 /* 4state loss model algorithm (used also for GI model) 295 * Extracts a value from the markov 4 state loss generator, 296 * if it is 1 drops a packet and if needed writes the event in 297 * the kernel logs 298 */ 299 return loss_4state(q); 300 301 case CLG_GILB_ELL: 302 /* Gilbert-Elliot loss model algorithm 303 * Extracts a value from the Gilbert-Elliot loss generator, 304 * if it is 1 drops a packet and if needed writes the event in 305 * the kernel logs 306 */ 307 return loss_gilb_ell(q); 308 } 309 310 return false; /* not reached */ 311 } 312 313 314 /* tabledist - return a pseudo-randomly distributed value with mean mu and 315 * std deviation sigma. Uses table lookup to approximate the desired 316 * distribution, and a uniformly-distributed pseudo-random source. 317 */ 318 static s64 tabledist(s64 mu, s32 sigma, 319 struct crndstate *state, 320 const struct disttable *dist) 321 { 322 s64 x; 323 long t; 324 u32 rnd; 325 326 if (sigma == 0) 327 return mu; 328 329 rnd = get_crandom(state); 330 331 /* default uniform distribution */ 332 if (dist == NULL) 333 return ((rnd % (2 * sigma)) + mu) - sigma; 334 335 t = dist->table[rnd % dist->size]; 336 x = (sigma % NETEM_DIST_SCALE) * t; 337 if (x >= 0) 338 x += NETEM_DIST_SCALE/2; 339 else 340 x -= NETEM_DIST_SCALE/2; 341 342 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu; 343 } 344 345 static u64 packet_time_ns(u64 len, const struct netem_sched_data *q) 346 { 347 len += q->packet_overhead; 348 349 if (q->cell_size) { 350 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal); 351 352 if (len > cells * q->cell_size) /* extra cell needed for remainder */ 353 cells++; 354 len = cells * (q->cell_size + q->cell_overhead); 355 } 356 357 return div64_u64(len * NSEC_PER_SEC, q->rate); 358 } 359 360 static void tfifo_reset(struct Qdisc *sch) 361 { 362 struct netem_sched_data *q = qdisc_priv(sch); 363 struct rb_node *p = rb_first(&q->t_root); 364 365 while (p) { 366 struct sk_buff *skb = rb_to_skb(p); 367 368 p = rb_next(p); 369 rb_erase(&skb->rbnode, &q->t_root); 370 rtnl_kfree_skbs(skb, skb); 371 } 372 373 rtnl_kfree_skbs(q->t_head, q->t_tail); 374 q->t_head = NULL; 375 q->t_tail = NULL; 376 } 377 378 static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch) 379 { 380 struct netem_sched_data *q = qdisc_priv(sch); 381 u64 tnext = netem_skb_cb(nskb)->time_to_send; 382 383 if (!q->t_tail || tnext >= netem_skb_cb(q->t_tail)->time_to_send) { 384 if (q->t_tail) 385 q->t_tail->next = nskb; 386 else 387 q->t_head = nskb; 388 q->t_tail = nskb; 389 } else { 390 struct rb_node **p = &q->t_root.rb_node, *parent = NULL; 391 392 while (*p) { 393 struct sk_buff *skb; 394 395 parent = *p; 396 skb = rb_to_skb(parent); 397 if (tnext >= netem_skb_cb(skb)->time_to_send) 398 p = &parent->rb_right; 399 else 400 p = &parent->rb_left; 401 } 402 rb_link_node(&nskb->rbnode, parent, p); 403 rb_insert_color(&nskb->rbnode, &q->t_root); 404 } 405 sch->q.qlen++; 406 } 407 408 /* netem can't properly corrupt a megapacket (like we get from GSO), so instead 409 * when we statistically choose to corrupt one, we instead segment it, returning 410 * the first packet to be corrupted, and re-enqueue the remaining frames 411 */ 412 static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch, 413 struct sk_buff **to_free) 414 { 415 struct sk_buff *segs; 416 netdev_features_t features = netif_skb_features(skb); 417 418 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 419 420 if (IS_ERR_OR_NULL(segs)) { 421 qdisc_drop(skb, sch, to_free); 422 return NULL; 423 } 424 consume_skb(skb); 425 return segs; 426 } 427 428 /* 429 * Insert one skb into qdisc. 430 * Note: parent depends on return value to account for queue length. 431 * NET_XMIT_DROP: queue length didn't change. 432 * NET_XMIT_SUCCESS: one skb was queued. 433 */ 434 static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, 435 struct sk_buff **to_free) 436 { 437 struct netem_sched_data *q = qdisc_priv(sch); 438 /* We don't fill cb now as skb_unshare() may invalidate it */ 439 struct netem_skb_cb *cb; 440 struct sk_buff *skb2; 441 struct sk_buff *segs = NULL; 442 unsigned int len = 0, last_len, prev_len = qdisc_pkt_len(skb); 443 int nb = 0; 444 int count = 1; 445 int rc = NET_XMIT_SUCCESS; 446 int rc_drop = NET_XMIT_DROP; 447 448 /* Do not fool qdisc_drop_all() */ 449 skb->prev = NULL; 450 451 /* Random duplication */ 452 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)) 453 ++count; 454 455 /* Drop packet? */ 456 if (loss_event(q)) { 457 if (q->ecn && INET_ECN_set_ce(skb)) 458 qdisc_qstats_drop(sch); /* mark packet */ 459 else 460 --count; 461 } 462 if (count == 0) { 463 qdisc_qstats_drop(sch); 464 __qdisc_drop(skb, to_free); 465 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 466 } 467 468 /* If a delay is expected, orphan the skb. (orphaning usually takes 469 * place at TX completion time, so _before_ the link transit delay) 470 */ 471 if (q->latency || q->jitter || q->rate) 472 skb_orphan_partial(skb); 473 474 /* 475 * If we need to duplicate packet, then re-insert at top of the 476 * qdisc tree, since parent queuer expects that only one 477 * skb will be queued. 478 */ 479 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) { 480 struct Qdisc *rootq = qdisc_root(sch); 481 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */ 482 483 q->duplicate = 0; 484 rootq->enqueue(skb2, rootq, to_free); 485 q->duplicate = dupsave; 486 rc_drop = NET_XMIT_SUCCESS; 487 } 488 489 /* 490 * Randomized packet corruption. 491 * Make copy if needed since we are modifying 492 * If packet is going to be hardware checksummed, then 493 * do it now in software before we mangle it. 494 */ 495 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) { 496 if (skb_is_gso(skb)) { 497 segs = netem_segment(skb, sch, to_free); 498 if (!segs) 499 return rc_drop; 500 } else { 501 segs = skb; 502 } 503 504 skb = segs; 505 segs = segs->next; 506 507 skb = skb_unshare(skb, GFP_ATOMIC); 508 if (unlikely(!skb)) { 509 qdisc_qstats_drop(sch); 510 goto finish_segs; 511 } 512 if (skb->ip_summed == CHECKSUM_PARTIAL && 513 skb_checksum_help(skb)) { 514 qdisc_drop(skb, sch, to_free); 515 goto finish_segs; 516 } 517 518 skb->data[prandom_u32() % skb_headlen(skb)] ^= 519 1<<(prandom_u32() % 8); 520 } 521 522 if (unlikely(sch->q.qlen >= sch->limit)) { 523 qdisc_drop_all(skb, sch, to_free); 524 return rc_drop; 525 } 526 527 qdisc_qstats_backlog_inc(sch, skb); 528 529 cb = netem_skb_cb(skb); 530 if (q->gap == 0 || /* not doing reordering */ 531 q->counter < q->gap - 1 || /* inside last reordering gap */ 532 q->reorder < get_crandom(&q->reorder_cor)) { 533 u64 now; 534 s64 delay; 535 536 delay = tabledist(q->latency, q->jitter, 537 &q->delay_cor, q->delay_dist); 538 539 now = ktime_get_ns(); 540 541 if (q->rate) { 542 struct netem_skb_cb *last = NULL; 543 544 if (sch->q.tail) 545 last = netem_skb_cb(sch->q.tail); 546 if (q->t_root.rb_node) { 547 struct sk_buff *t_skb; 548 struct netem_skb_cb *t_last; 549 550 t_skb = skb_rb_last(&q->t_root); 551 t_last = netem_skb_cb(t_skb); 552 if (!last || 553 t_last->time_to_send > last->time_to_send) 554 last = t_last; 555 } 556 if (q->t_tail) { 557 struct netem_skb_cb *t_last = 558 netem_skb_cb(q->t_tail); 559 560 if (!last || 561 t_last->time_to_send > last->time_to_send) 562 last = t_last; 563 } 564 565 if (last) { 566 /* 567 * Last packet in queue is reference point (now), 568 * calculate this time bonus and subtract 569 * from delay. 570 */ 571 delay -= last->time_to_send - now; 572 delay = max_t(s64, 0, delay); 573 now = last->time_to_send; 574 } 575 576 delay += packet_time_ns(qdisc_pkt_len(skb), q); 577 } 578 579 cb->time_to_send = now + delay; 580 ++q->counter; 581 tfifo_enqueue(skb, sch); 582 } else { 583 /* 584 * Do re-ordering by putting one out of N packets at the front 585 * of the queue. 586 */ 587 cb->time_to_send = ktime_get_ns(); 588 q->counter = 0; 589 590 __qdisc_enqueue_head(skb, &sch->q); 591 sch->qstats.requeues++; 592 } 593 594 finish_segs: 595 if (segs) { 596 while (segs) { 597 skb2 = segs->next; 598 skb_mark_not_on_list(segs); 599 qdisc_skb_cb(segs)->pkt_len = segs->len; 600 last_len = segs->len; 601 rc = qdisc_enqueue(segs, sch, to_free); 602 if (rc != NET_XMIT_SUCCESS) { 603 if (net_xmit_drop_count(rc)) 604 qdisc_qstats_drop(sch); 605 } else { 606 nb++; 607 len += last_len; 608 } 609 segs = skb2; 610 } 611 sch->q.qlen += nb; 612 if (nb > 1) 613 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len); 614 } 615 return NET_XMIT_SUCCESS; 616 } 617 618 /* Delay the next round with a new future slot with a 619 * correct number of bytes and packets. 620 */ 621 622 static void get_slot_next(struct netem_sched_data *q, u64 now) 623 { 624 s64 next_delay; 625 626 if (!q->slot_dist) 627 next_delay = q->slot_config.min_delay + 628 (prandom_u32() * 629 (q->slot_config.max_delay - 630 q->slot_config.min_delay) >> 32); 631 else 632 next_delay = tabledist(q->slot_config.dist_delay, 633 (s32)(q->slot_config.dist_jitter), 634 NULL, q->slot_dist); 635 636 q->slot.slot_next = now + next_delay; 637 q->slot.packets_left = q->slot_config.max_packets; 638 q->slot.bytes_left = q->slot_config.max_bytes; 639 } 640 641 static struct sk_buff *netem_peek(struct netem_sched_data *q) 642 { 643 struct sk_buff *skb = skb_rb_first(&q->t_root); 644 u64 t1, t2; 645 646 if (!skb) 647 return q->t_head; 648 if (!q->t_head) 649 return skb; 650 651 t1 = netem_skb_cb(skb)->time_to_send; 652 t2 = netem_skb_cb(q->t_head)->time_to_send; 653 if (t1 < t2) 654 return skb; 655 return q->t_head; 656 } 657 658 static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb) 659 { 660 if (skb == q->t_head) { 661 q->t_head = skb->next; 662 if (!q->t_head) 663 q->t_tail = NULL; 664 } else { 665 rb_erase(&skb->rbnode, &q->t_root); 666 } 667 } 668 669 static struct sk_buff *netem_dequeue(struct Qdisc *sch) 670 { 671 struct netem_sched_data *q = qdisc_priv(sch); 672 struct sk_buff *skb; 673 674 tfifo_dequeue: 675 skb = __qdisc_dequeue_head(&sch->q); 676 if (skb) { 677 qdisc_qstats_backlog_dec(sch, skb); 678 deliver: 679 qdisc_bstats_update(sch, skb); 680 return skb; 681 } 682 skb = netem_peek(q); 683 if (skb) { 684 u64 time_to_send; 685 u64 now = ktime_get_ns(); 686 687 /* if more time remaining? */ 688 time_to_send = netem_skb_cb(skb)->time_to_send; 689 if (q->slot.slot_next && q->slot.slot_next < time_to_send) 690 get_slot_next(q, now); 691 692 if (time_to_send <= now && q->slot.slot_next <= now) { 693 netem_erase_head(q, skb); 694 sch->q.qlen--; 695 qdisc_qstats_backlog_dec(sch, skb); 696 skb->next = NULL; 697 skb->prev = NULL; 698 /* skb->dev shares skb->rbnode area, 699 * we need to restore its value. 700 */ 701 skb->dev = qdisc_dev(sch); 702 703 if (q->slot.slot_next) { 704 q->slot.packets_left--; 705 q->slot.bytes_left -= qdisc_pkt_len(skb); 706 if (q->slot.packets_left <= 0 || 707 q->slot.bytes_left <= 0) 708 get_slot_next(q, now); 709 } 710 711 if (q->qdisc) { 712 unsigned int pkt_len = qdisc_pkt_len(skb); 713 struct sk_buff *to_free = NULL; 714 int err; 715 716 err = qdisc_enqueue(skb, q->qdisc, &to_free); 717 kfree_skb_list(to_free); 718 if (err != NET_XMIT_SUCCESS && 719 net_xmit_drop_count(err)) { 720 qdisc_qstats_drop(sch); 721 qdisc_tree_reduce_backlog(sch, 1, 722 pkt_len); 723 } 724 goto tfifo_dequeue; 725 } 726 goto deliver; 727 } 728 729 if (q->qdisc) { 730 skb = q->qdisc->ops->dequeue(q->qdisc); 731 if (skb) 732 goto deliver; 733 } 734 735 qdisc_watchdog_schedule_ns(&q->watchdog, 736 max(time_to_send, 737 q->slot.slot_next)); 738 } 739 740 if (q->qdisc) { 741 skb = q->qdisc->ops->dequeue(q->qdisc); 742 if (skb) 743 goto deliver; 744 } 745 return NULL; 746 } 747 748 static void netem_reset(struct Qdisc *sch) 749 { 750 struct netem_sched_data *q = qdisc_priv(sch); 751 752 qdisc_reset_queue(sch); 753 tfifo_reset(sch); 754 if (q->qdisc) 755 qdisc_reset(q->qdisc); 756 qdisc_watchdog_cancel(&q->watchdog); 757 } 758 759 static void dist_free(struct disttable *d) 760 { 761 kvfree(d); 762 } 763 764 /* 765 * Distribution data is a variable size payload containing 766 * signed 16 bit values. 767 */ 768 769 static int get_dist_table(struct Qdisc *sch, struct disttable **tbl, 770 const struct nlattr *attr) 771 { 772 size_t n = nla_len(attr)/sizeof(__s16); 773 const __s16 *data = nla_data(attr); 774 spinlock_t *root_lock; 775 struct disttable *d; 776 int i; 777 778 if (n > NETEM_DIST_MAX) 779 return -EINVAL; 780 781 d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL); 782 if (!d) 783 return -ENOMEM; 784 785 d->size = n; 786 for (i = 0; i < n; i++) 787 d->table[i] = data[i]; 788 789 root_lock = qdisc_root_sleeping_lock(sch); 790 791 spin_lock_bh(root_lock); 792 swap(*tbl, d); 793 spin_unlock_bh(root_lock); 794 795 dist_free(d); 796 return 0; 797 } 798 799 static void get_slot(struct netem_sched_data *q, const struct nlattr *attr) 800 { 801 const struct tc_netem_slot *c = nla_data(attr); 802 803 q->slot_config = *c; 804 if (q->slot_config.max_packets == 0) 805 q->slot_config.max_packets = INT_MAX; 806 if (q->slot_config.max_bytes == 0) 807 q->slot_config.max_bytes = INT_MAX; 808 q->slot.packets_left = q->slot_config.max_packets; 809 q->slot.bytes_left = q->slot_config.max_bytes; 810 if (q->slot_config.min_delay | q->slot_config.max_delay | 811 q->slot_config.dist_jitter) 812 q->slot.slot_next = ktime_get_ns(); 813 else 814 q->slot.slot_next = 0; 815 } 816 817 static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr) 818 { 819 const struct tc_netem_corr *c = nla_data(attr); 820 821 init_crandom(&q->delay_cor, c->delay_corr); 822 init_crandom(&q->loss_cor, c->loss_corr); 823 init_crandom(&q->dup_cor, c->dup_corr); 824 } 825 826 static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr) 827 { 828 const struct tc_netem_reorder *r = nla_data(attr); 829 830 q->reorder = r->probability; 831 init_crandom(&q->reorder_cor, r->correlation); 832 } 833 834 static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr) 835 { 836 const struct tc_netem_corrupt *r = nla_data(attr); 837 838 q->corrupt = r->probability; 839 init_crandom(&q->corrupt_cor, r->correlation); 840 } 841 842 static void get_rate(struct netem_sched_data *q, const struct nlattr *attr) 843 { 844 const struct tc_netem_rate *r = nla_data(attr); 845 846 q->rate = r->rate; 847 q->packet_overhead = r->packet_overhead; 848 q->cell_size = r->cell_size; 849 q->cell_overhead = r->cell_overhead; 850 if (q->cell_size) 851 q->cell_size_reciprocal = reciprocal_value(q->cell_size); 852 else 853 q->cell_size_reciprocal = (struct reciprocal_value) { 0 }; 854 } 855 856 static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr) 857 { 858 const struct nlattr *la; 859 int rem; 860 861 nla_for_each_nested(la, attr, rem) { 862 u16 type = nla_type(la); 863 864 switch (type) { 865 case NETEM_LOSS_GI: { 866 const struct tc_netem_gimodel *gi = nla_data(la); 867 868 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) { 869 pr_info("netem: incorrect gi model size\n"); 870 return -EINVAL; 871 } 872 873 q->loss_model = CLG_4_STATES; 874 875 q->clg.state = TX_IN_GAP_PERIOD; 876 q->clg.a1 = gi->p13; 877 q->clg.a2 = gi->p31; 878 q->clg.a3 = gi->p32; 879 q->clg.a4 = gi->p14; 880 q->clg.a5 = gi->p23; 881 break; 882 } 883 884 case NETEM_LOSS_GE: { 885 const struct tc_netem_gemodel *ge = nla_data(la); 886 887 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) { 888 pr_info("netem: incorrect ge model size\n"); 889 return -EINVAL; 890 } 891 892 q->loss_model = CLG_GILB_ELL; 893 q->clg.state = GOOD_STATE; 894 q->clg.a1 = ge->p; 895 q->clg.a2 = ge->r; 896 q->clg.a3 = ge->h; 897 q->clg.a4 = ge->k1; 898 break; 899 } 900 901 default: 902 pr_info("netem: unknown loss type %u\n", type); 903 return -EINVAL; 904 } 905 } 906 907 return 0; 908 } 909 910 static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = { 911 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) }, 912 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) }, 913 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) }, 914 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) }, 915 [TCA_NETEM_LOSS] = { .type = NLA_NESTED }, 916 [TCA_NETEM_ECN] = { .type = NLA_U32 }, 917 [TCA_NETEM_RATE64] = { .type = NLA_U64 }, 918 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 }, 919 [TCA_NETEM_JITTER64] = { .type = NLA_S64 }, 920 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) }, 921 }; 922 923 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla, 924 const struct nla_policy *policy, int len) 925 { 926 int nested_len = nla_len(nla) - NLA_ALIGN(len); 927 928 if (nested_len < 0) { 929 pr_info("netem: invalid attributes len %d\n", nested_len); 930 return -EINVAL; 931 } 932 933 if (nested_len >= nla_attr_size(0)) 934 return nla_parse_deprecated(tb, maxtype, 935 nla_data(nla) + NLA_ALIGN(len), 936 nested_len, policy, NULL); 937 938 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); 939 return 0; 940 } 941 942 /* Parse netlink message to set options */ 943 static int netem_change(struct Qdisc *sch, struct nlattr *opt, 944 struct netlink_ext_ack *extack) 945 { 946 struct netem_sched_data *q = qdisc_priv(sch); 947 struct nlattr *tb[TCA_NETEM_MAX + 1]; 948 struct tc_netem_qopt *qopt; 949 struct clgstate old_clg; 950 int old_loss_model = CLG_RANDOM; 951 int ret; 952 953 if (opt == NULL) 954 return -EINVAL; 955 956 qopt = nla_data(opt); 957 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt)); 958 if (ret < 0) 959 return ret; 960 961 /* backup q->clg and q->loss_model */ 962 old_clg = q->clg; 963 old_loss_model = q->loss_model; 964 965 if (tb[TCA_NETEM_LOSS]) { 966 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]); 967 if (ret) { 968 q->loss_model = old_loss_model; 969 return ret; 970 } 971 } else { 972 q->loss_model = CLG_RANDOM; 973 } 974 975 if (tb[TCA_NETEM_DELAY_DIST]) { 976 ret = get_dist_table(sch, &q->delay_dist, 977 tb[TCA_NETEM_DELAY_DIST]); 978 if (ret) 979 goto get_table_failure; 980 } 981 982 if (tb[TCA_NETEM_SLOT_DIST]) { 983 ret = get_dist_table(sch, &q->slot_dist, 984 tb[TCA_NETEM_SLOT_DIST]); 985 if (ret) 986 goto get_table_failure; 987 } 988 989 sch->limit = qopt->limit; 990 991 q->latency = PSCHED_TICKS2NS(qopt->latency); 992 q->jitter = PSCHED_TICKS2NS(qopt->jitter); 993 q->limit = qopt->limit; 994 q->gap = qopt->gap; 995 q->counter = 0; 996 q->loss = qopt->loss; 997 q->duplicate = qopt->duplicate; 998 999 /* for compatibility with earlier versions. 1000 * if gap is set, need to assume 100% probability 1001 */ 1002 if (q->gap) 1003 q->reorder = ~0; 1004 1005 if (tb[TCA_NETEM_CORR]) 1006 get_correlation(q, tb[TCA_NETEM_CORR]); 1007 1008 if (tb[TCA_NETEM_REORDER]) 1009 get_reorder(q, tb[TCA_NETEM_REORDER]); 1010 1011 if (tb[TCA_NETEM_CORRUPT]) 1012 get_corrupt(q, tb[TCA_NETEM_CORRUPT]); 1013 1014 if (tb[TCA_NETEM_RATE]) 1015 get_rate(q, tb[TCA_NETEM_RATE]); 1016 1017 if (tb[TCA_NETEM_RATE64]) 1018 q->rate = max_t(u64, q->rate, 1019 nla_get_u64(tb[TCA_NETEM_RATE64])); 1020 1021 if (tb[TCA_NETEM_LATENCY64]) 1022 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]); 1023 1024 if (tb[TCA_NETEM_JITTER64]) 1025 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]); 1026 1027 if (tb[TCA_NETEM_ECN]) 1028 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]); 1029 1030 if (tb[TCA_NETEM_SLOT]) 1031 get_slot(q, tb[TCA_NETEM_SLOT]); 1032 1033 return ret; 1034 1035 get_table_failure: 1036 /* recover clg and loss_model, in case of 1037 * q->clg and q->loss_model were modified 1038 * in get_loss_clg() 1039 */ 1040 q->clg = old_clg; 1041 q->loss_model = old_loss_model; 1042 return ret; 1043 } 1044 1045 static int netem_init(struct Qdisc *sch, struct nlattr *opt, 1046 struct netlink_ext_ack *extack) 1047 { 1048 struct netem_sched_data *q = qdisc_priv(sch); 1049 int ret; 1050 1051 qdisc_watchdog_init(&q->watchdog, sch); 1052 1053 if (!opt) 1054 return -EINVAL; 1055 1056 q->loss_model = CLG_RANDOM; 1057 ret = netem_change(sch, opt, extack); 1058 if (ret) 1059 pr_info("netem: change failed\n"); 1060 return ret; 1061 } 1062 1063 static void netem_destroy(struct Qdisc *sch) 1064 { 1065 struct netem_sched_data *q = qdisc_priv(sch); 1066 1067 qdisc_watchdog_cancel(&q->watchdog); 1068 if (q->qdisc) 1069 qdisc_put(q->qdisc); 1070 dist_free(q->delay_dist); 1071 dist_free(q->slot_dist); 1072 } 1073 1074 static int dump_loss_model(const struct netem_sched_data *q, 1075 struct sk_buff *skb) 1076 { 1077 struct nlattr *nest; 1078 1079 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS); 1080 if (nest == NULL) 1081 goto nla_put_failure; 1082 1083 switch (q->loss_model) { 1084 case CLG_RANDOM: 1085 /* legacy loss model */ 1086 nla_nest_cancel(skb, nest); 1087 return 0; /* no data */ 1088 1089 case CLG_4_STATES: { 1090 struct tc_netem_gimodel gi = { 1091 .p13 = q->clg.a1, 1092 .p31 = q->clg.a2, 1093 .p32 = q->clg.a3, 1094 .p14 = q->clg.a4, 1095 .p23 = q->clg.a5, 1096 }; 1097 1098 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi)) 1099 goto nla_put_failure; 1100 break; 1101 } 1102 case CLG_GILB_ELL: { 1103 struct tc_netem_gemodel ge = { 1104 .p = q->clg.a1, 1105 .r = q->clg.a2, 1106 .h = q->clg.a3, 1107 .k1 = q->clg.a4, 1108 }; 1109 1110 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge)) 1111 goto nla_put_failure; 1112 break; 1113 } 1114 } 1115 1116 nla_nest_end(skb, nest); 1117 return 0; 1118 1119 nla_put_failure: 1120 nla_nest_cancel(skb, nest); 1121 return -1; 1122 } 1123 1124 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb) 1125 { 1126 const struct netem_sched_data *q = qdisc_priv(sch); 1127 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb); 1128 struct tc_netem_qopt qopt; 1129 struct tc_netem_corr cor; 1130 struct tc_netem_reorder reorder; 1131 struct tc_netem_corrupt corrupt; 1132 struct tc_netem_rate rate; 1133 struct tc_netem_slot slot; 1134 1135 qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency), 1136 UINT_MAX); 1137 qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter), 1138 UINT_MAX); 1139 qopt.limit = q->limit; 1140 qopt.loss = q->loss; 1141 qopt.gap = q->gap; 1142 qopt.duplicate = q->duplicate; 1143 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt)) 1144 goto nla_put_failure; 1145 1146 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency)) 1147 goto nla_put_failure; 1148 1149 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter)) 1150 goto nla_put_failure; 1151 1152 cor.delay_corr = q->delay_cor.rho; 1153 cor.loss_corr = q->loss_cor.rho; 1154 cor.dup_corr = q->dup_cor.rho; 1155 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor)) 1156 goto nla_put_failure; 1157 1158 reorder.probability = q->reorder; 1159 reorder.correlation = q->reorder_cor.rho; 1160 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder)) 1161 goto nla_put_failure; 1162 1163 corrupt.probability = q->corrupt; 1164 corrupt.correlation = q->corrupt_cor.rho; 1165 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt)) 1166 goto nla_put_failure; 1167 1168 if (q->rate >= (1ULL << 32)) { 1169 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate, 1170 TCA_NETEM_PAD)) 1171 goto nla_put_failure; 1172 rate.rate = ~0U; 1173 } else { 1174 rate.rate = q->rate; 1175 } 1176 rate.packet_overhead = q->packet_overhead; 1177 rate.cell_size = q->cell_size; 1178 rate.cell_overhead = q->cell_overhead; 1179 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate)) 1180 goto nla_put_failure; 1181 1182 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn)) 1183 goto nla_put_failure; 1184 1185 if (dump_loss_model(q, skb) != 0) 1186 goto nla_put_failure; 1187 1188 if (q->slot_config.min_delay | q->slot_config.max_delay | 1189 q->slot_config.dist_jitter) { 1190 slot = q->slot_config; 1191 if (slot.max_packets == INT_MAX) 1192 slot.max_packets = 0; 1193 if (slot.max_bytes == INT_MAX) 1194 slot.max_bytes = 0; 1195 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot)) 1196 goto nla_put_failure; 1197 } 1198 1199 return nla_nest_end(skb, nla); 1200 1201 nla_put_failure: 1202 nlmsg_trim(skb, nla); 1203 return -1; 1204 } 1205 1206 static int netem_dump_class(struct Qdisc *sch, unsigned long cl, 1207 struct sk_buff *skb, struct tcmsg *tcm) 1208 { 1209 struct netem_sched_data *q = qdisc_priv(sch); 1210 1211 if (cl != 1 || !q->qdisc) /* only one class */ 1212 return -ENOENT; 1213 1214 tcm->tcm_handle |= TC_H_MIN(1); 1215 tcm->tcm_info = q->qdisc->handle; 1216 1217 return 0; 1218 } 1219 1220 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 1221 struct Qdisc **old, struct netlink_ext_ack *extack) 1222 { 1223 struct netem_sched_data *q = qdisc_priv(sch); 1224 1225 *old = qdisc_replace(sch, new, &q->qdisc); 1226 return 0; 1227 } 1228 1229 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg) 1230 { 1231 struct netem_sched_data *q = qdisc_priv(sch); 1232 return q->qdisc; 1233 } 1234 1235 static unsigned long netem_find(struct Qdisc *sch, u32 classid) 1236 { 1237 return 1; 1238 } 1239 1240 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker) 1241 { 1242 if (!walker->stop) { 1243 if (walker->count >= walker->skip) 1244 if (walker->fn(sch, 1, walker) < 0) { 1245 walker->stop = 1; 1246 return; 1247 } 1248 walker->count++; 1249 } 1250 } 1251 1252 static const struct Qdisc_class_ops netem_class_ops = { 1253 .graft = netem_graft, 1254 .leaf = netem_leaf, 1255 .find = netem_find, 1256 .walk = netem_walk, 1257 .dump = netem_dump_class, 1258 }; 1259 1260 static struct Qdisc_ops netem_qdisc_ops __read_mostly = { 1261 .id = "netem", 1262 .cl_ops = &netem_class_ops, 1263 .priv_size = sizeof(struct netem_sched_data), 1264 .enqueue = netem_enqueue, 1265 .dequeue = netem_dequeue, 1266 .peek = qdisc_peek_dequeued, 1267 .init = netem_init, 1268 .reset = netem_reset, 1269 .destroy = netem_destroy, 1270 .change = netem_change, 1271 .dump = netem_dump, 1272 .owner = THIS_MODULE, 1273 }; 1274 1275 1276 static int __init netem_module_init(void) 1277 { 1278 pr_info("netem: version " VERSION "\n"); 1279 return register_qdisc(&netem_qdisc_ops); 1280 } 1281 static void __exit netem_module_exit(void) 1282 { 1283 unregister_qdisc(&netem_qdisc_ops); 1284 } 1285 module_init(netem_module_init) 1286 module_exit(netem_module_exit) 1287 MODULE_LICENSE("GPL"); 1288