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 67struct disttable { 68 u32 size; 69 s16 table[]; 70}; 71 72struct 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 */ 157struct netem_skb_cb { 158 u64 time_to_send; 159}; 160 161static 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 */ 171static 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 */ 181static 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 */ 200static 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 */ 265static 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 286static 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 */ 318static 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 * (u32)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 345static 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 360static 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 378static 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 */ 412static 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 */ 434static 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 prev_len = qdisc_pkt_len(skb); 443 int count = 1; 444 int rc = NET_XMIT_SUCCESS; 445 int rc_drop = NET_XMIT_DROP; 446 447 /* Do not fool qdisc_drop_all() */ 448 skb->prev = NULL; 449 450 /* Random duplication */ 451 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)) 452 ++count; 453 454 /* Drop packet? */ 455 if (loss_event(q)) { 456 if (q->ecn && INET_ECN_set_ce(skb)) 457 qdisc_qstats_drop(sch); /* mark packet */ 458 else 459 --count; 460 } 461 if (count == 0) { 462 qdisc_qstats_drop(sch); 463 __qdisc_drop(skb, to_free); 464 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 465 } 466 467 /* If a delay is expected, orphan the skb. (orphaning usually takes 468 * place at TX completion time, so _before_ the link transit delay) 469 */ 470 if (q->latency || q->jitter || q->rate) 471 skb_orphan_partial(skb); 472 473 /* 474 * If we need to duplicate packet, then re-insert at top of the 475 * qdisc tree, since parent queuer expects that only one 476 * skb will be queued. 477 */ 478 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) { 479 struct Qdisc *rootq = qdisc_root_bh(sch); 480 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */ 481 482 q->duplicate = 0; 483 rootq->enqueue(skb2, rootq, to_free); 484 q->duplicate = dupsave; 485 rc_drop = NET_XMIT_SUCCESS; 486 } 487 488 /* 489 * Randomized packet corruption. 490 * Make copy if needed since we are modifying 491 * If packet is going to be hardware checksummed, then 492 * do it now in software before we mangle it. 493 */ 494 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) { 495 if (skb_is_gso(skb)) { 496 skb = netem_segment(skb, sch, to_free); 497 if (!skb) 498 return rc_drop; 499 segs = skb->next; 500 skb_mark_not_on_list(skb); 501 qdisc_skb_cb(skb)->pkt_len = skb->len; 502 } 503 504 skb = skb_unshare(skb, GFP_ATOMIC); 505 if (unlikely(!skb)) { 506 qdisc_qstats_drop(sch); 507 goto finish_segs; 508 } 509 if (skb->ip_summed == CHECKSUM_PARTIAL && 510 skb_checksum_help(skb)) { 511 qdisc_drop(skb, sch, to_free); 512 skb = NULL; 513 goto finish_segs; 514 } 515 516 skb->data[prandom_u32() % skb_headlen(skb)] ^= 517 1<<(prandom_u32() % 8); 518 } 519 520 if (unlikely(sch->q.qlen >= sch->limit)) { 521 /* re-link segs, so that qdisc_drop_all() frees them all */ 522 skb->next = segs; 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 594finish_segs: 595 if (segs) { 596 unsigned int len, last_len; 597 int nb; 598 599 len = skb ? skb->len : 0; 600 nb = skb ? 1 : 0; 601 602 while (segs) { 603 skb2 = segs->next; 604 skb_mark_not_on_list(segs); 605 qdisc_skb_cb(segs)->pkt_len = segs->len; 606 last_len = segs->len; 607 rc = qdisc_enqueue(segs, sch, to_free); 608 if (rc != NET_XMIT_SUCCESS) { 609 if (net_xmit_drop_count(rc)) 610 qdisc_qstats_drop(sch); 611 } else { 612 nb++; 613 len += last_len; 614 } 615 segs = skb2; 616 } 617 /* Parent qdiscs accounted for 1 skb of size @prev_len */ 618 qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len)); 619 } else if (!skb) { 620 return NET_XMIT_DROP; 621 } 622 return NET_XMIT_SUCCESS; 623} 624 625/* Delay the next round with a new future slot with a 626 * correct number of bytes and packets. 627 */ 628 629static void get_slot_next(struct netem_sched_data *q, u64 now) 630{ 631 s64 next_delay; 632 633 if (!q->slot_dist) 634 next_delay = q->slot_config.min_delay + 635 (prandom_u32() * 636 (q->slot_config.max_delay - 637 q->slot_config.min_delay) >> 32); 638 else 639 next_delay = tabledist(q->slot_config.dist_delay, 640 (s32)(q->slot_config.dist_jitter), 641 NULL, q->slot_dist); 642 643 q->slot.slot_next = now + next_delay; 644 q->slot.packets_left = q->slot_config.max_packets; 645 q->slot.bytes_left = q->slot_config.max_bytes; 646} 647 648static struct sk_buff *netem_peek(struct netem_sched_data *q) 649{ 650 struct sk_buff *skb = skb_rb_first(&q->t_root); 651 u64 t1, t2; 652 653 if (!skb) 654 return q->t_head; 655 if (!q->t_head) 656 return skb; 657 658 t1 = netem_skb_cb(skb)->time_to_send; 659 t2 = netem_skb_cb(q->t_head)->time_to_send; 660 if (t1 < t2) 661 return skb; 662 return q->t_head; 663} 664 665static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb) 666{ 667 if (skb == q->t_head) { 668 q->t_head = skb->next; 669 if (!q->t_head) 670 q->t_tail = NULL; 671 } else { 672 rb_erase(&skb->rbnode, &q->t_root); 673 } 674} 675 676static struct sk_buff *netem_dequeue(struct Qdisc *sch) 677{ 678 struct netem_sched_data *q = qdisc_priv(sch); 679 struct sk_buff *skb; 680 681tfifo_dequeue: 682 skb = __qdisc_dequeue_head(&sch->q); 683 if (skb) { 684 qdisc_qstats_backlog_dec(sch, skb); 685deliver: 686 qdisc_bstats_update(sch, skb); 687 return skb; 688 } 689 skb = netem_peek(q); 690 if (skb) { 691 u64 time_to_send; 692 u64 now = ktime_get_ns(); 693 694 /* if more time remaining? */ 695 time_to_send = netem_skb_cb(skb)->time_to_send; 696 if (q->slot.slot_next && q->slot.slot_next < time_to_send) 697 get_slot_next(q, now); 698 699 if (time_to_send <= now && q->slot.slot_next <= now) { 700 netem_erase_head(q, skb); 701 sch->q.qlen--; 702 qdisc_qstats_backlog_dec(sch, skb); 703 skb->next = NULL; 704 skb->prev = NULL; 705 /* skb->dev shares skb->rbnode area, 706 * we need to restore its value. 707 */ 708 skb->dev = qdisc_dev(sch); 709 710 if (q->slot.slot_next) { 711 q->slot.packets_left--; 712 q->slot.bytes_left -= qdisc_pkt_len(skb); 713 if (q->slot.packets_left <= 0 || 714 q->slot.bytes_left <= 0) 715 get_slot_next(q, now); 716 } 717 718 if (q->qdisc) { 719 unsigned int pkt_len = qdisc_pkt_len(skb); 720 struct sk_buff *to_free = NULL; 721 int err; 722 723 err = qdisc_enqueue(skb, q->qdisc, &to_free); 724 kfree_skb_list(to_free); 725 if (err != NET_XMIT_SUCCESS) { 726 if (net_xmit_drop_count(err)) 727 qdisc_qstats_drop(sch); 728 qdisc_tree_reduce_backlog(sch, 1, pkt_len); 729 } 730 goto tfifo_dequeue; 731 } 732 goto deliver; 733 } 734 735 if (q->qdisc) { 736 skb = q->qdisc->ops->dequeue(q->qdisc); 737 if (skb) 738 goto deliver; 739 } 740 741 qdisc_watchdog_schedule_ns(&q->watchdog, 742 max(time_to_send, 743 q->slot.slot_next)); 744 } 745 746 if (q->qdisc) { 747 skb = q->qdisc->ops->dequeue(q->qdisc); 748 if (skb) 749 goto deliver; 750 } 751 return NULL; 752} 753 754static void netem_reset(struct Qdisc *sch) 755{ 756 struct netem_sched_data *q = qdisc_priv(sch); 757 758 qdisc_reset_queue(sch); 759 tfifo_reset(sch); 760 if (q->qdisc) 761 qdisc_reset(q->qdisc); 762 qdisc_watchdog_cancel(&q->watchdog); 763} 764 765static void dist_free(struct disttable *d) 766{ 767 kvfree(d); 768} 769 770/* 771 * Distribution data is a variable size payload containing 772 * signed 16 bit values. 773 */ 774 775static int get_dist_table(struct disttable **tbl, const struct nlattr *attr) 776{ 777 size_t n = nla_len(attr)/sizeof(__s16); 778 const __s16 *data = nla_data(attr); 779 struct disttable *d; 780 int i; 781 782 if (!n || n > NETEM_DIST_MAX) 783 return -EINVAL; 784 785 d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL); 786 if (!d) 787 return -ENOMEM; 788 789 d->size = n; 790 for (i = 0; i < n; i++) 791 d->table[i] = data[i]; 792 793 *tbl = d; 794 return 0; 795} 796 797static void get_slot(struct netem_sched_data *q, const struct nlattr *attr) 798{ 799 const struct tc_netem_slot *c = nla_data(attr); 800 801 q->slot_config = *c; 802 if (q->slot_config.max_packets == 0) 803 q->slot_config.max_packets = INT_MAX; 804 if (q->slot_config.max_bytes == 0) 805 q->slot_config.max_bytes = INT_MAX; 806 807 /* capping dist_jitter to the range acceptable by tabledist() */ 808 q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter)); 809 810 q->slot.packets_left = q->slot_config.max_packets; 811 q->slot.bytes_left = q->slot_config.max_bytes; 812 if (q->slot_config.min_delay | q->slot_config.max_delay | 813 q->slot_config.dist_jitter) 814 q->slot.slot_next = ktime_get_ns(); 815 else 816 q->slot.slot_next = 0; 817} 818 819static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr) 820{ 821 const struct tc_netem_corr *c = nla_data(attr); 822 823 init_crandom(&q->delay_cor, c->delay_corr); 824 init_crandom(&q->loss_cor, c->loss_corr); 825 init_crandom(&q->dup_cor, c->dup_corr); 826} 827 828static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr) 829{ 830 const struct tc_netem_reorder *r = nla_data(attr); 831 832 q->reorder = r->probability; 833 init_crandom(&q->reorder_cor, r->correlation); 834} 835 836static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr) 837{ 838 const struct tc_netem_corrupt *r = nla_data(attr); 839 840 q->corrupt = r->probability; 841 init_crandom(&q->corrupt_cor, r->correlation); 842} 843 844static void get_rate(struct netem_sched_data *q, const struct nlattr *attr) 845{ 846 const struct tc_netem_rate *r = nla_data(attr); 847 848 q->rate = r->rate; 849 q->packet_overhead = r->packet_overhead; 850 q->cell_size = r->cell_size; 851 q->cell_overhead = r->cell_overhead; 852 if (q->cell_size) 853 q->cell_size_reciprocal = reciprocal_value(q->cell_size); 854 else 855 q->cell_size_reciprocal = (struct reciprocal_value) { 0 }; 856} 857 858static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr) 859{ 860 const struct nlattr *la; 861 int rem; 862 863 nla_for_each_nested(la, attr, rem) { 864 u16 type = nla_type(la); 865 866 switch (type) { 867 case NETEM_LOSS_GI: { 868 const struct tc_netem_gimodel *gi = nla_data(la); 869 870 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) { 871 pr_info("netem: incorrect gi model size\n"); 872 return -EINVAL; 873 } 874 875 q->loss_model = CLG_4_STATES; 876 877 q->clg.state = TX_IN_GAP_PERIOD; 878 q->clg.a1 = gi->p13; 879 q->clg.a2 = gi->p31; 880 q->clg.a3 = gi->p32; 881 q->clg.a4 = gi->p14; 882 q->clg.a5 = gi->p23; 883 break; 884 } 885 886 case NETEM_LOSS_GE: { 887 const struct tc_netem_gemodel *ge = nla_data(la); 888 889 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) { 890 pr_info("netem: incorrect ge model size\n"); 891 return -EINVAL; 892 } 893 894 q->loss_model = CLG_GILB_ELL; 895 q->clg.state = GOOD_STATE; 896 q->clg.a1 = ge->p; 897 q->clg.a2 = ge->r; 898 q->clg.a3 = ge->h; 899 q->clg.a4 = ge->k1; 900 break; 901 } 902 903 default: 904 pr_info("netem: unknown loss type %u\n", type); 905 return -EINVAL; 906 } 907 } 908 909 return 0; 910} 911 912static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = { 913 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) }, 914 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) }, 915 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) }, 916 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) }, 917 [TCA_NETEM_LOSS] = { .type = NLA_NESTED }, 918 [TCA_NETEM_ECN] = { .type = NLA_U32 }, 919 [TCA_NETEM_RATE64] = { .type = NLA_U64 }, 920 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 }, 921 [TCA_NETEM_JITTER64] = { .type = NLA_S64 }, 922 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) }, 923}; 924 925static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla, 926 const struct nla_policy *policy, int len) 927{ 928 int nested_len = nla_len(nla) - NLA_ALIGN(len); 929 930 if (nested_len < 0) { 931 pr_info("netem: invalid attributes len %d\n", nested_len); 932 return -EINVAL; 933 } 934 935 if (nested_len >= nla_attr_size(0)) 936 return nla_parse_deprecated(tb, maxtype, 937 nla_data(nla) + NLA_ALIGN(len), 938 nested_len, policy, NULL); 939 940 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); 941 return 0; 942} 943 944/* Parse netlink message to set options */ 945static int netem_change(struct Qdisc *sch, struct nlattr *opt, 946 struct netlink_ext_ack *extack) 947{ 948 struct netem_sched_data *q = qdisc_priv(sch); 949 struct nlattr *tb[TCA_NETEM_MAX + 1]; 950 struct disttable *delay_dist = NULL; 951 struct disttable *slot_dist = NULL; 952 struct tc_netem_qopt *qopt; 953 struct clgstate old_clg; 954 int old_loss_model = CLG_RANDOM; 955 int ret; 956 957 if (opt == NULL) 958 return -EINVAL; 959 960 qopt = nla_data(opt); 961 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt)); 962 if (ret < 0) 963 return ret; 964 965 if (tb[TCA_NETEM_DELAY_DIST]) { 966 ret = get_dist_table(&delay_dist, tb[TCA_NETEM_DELAY_DIST]); 967 if (ret) 968 goto table_free; 969 } 970 971 if (tb[TCA_NETEM_SLOT_DIST]) { 972 ret = get_dist_table(&slot_dist, tb[TCA_NETEM_SLOT_DIST]); 973 if (ret) 974 goto table_free; 975 } 976 977 sch_tree_lock(sch); 978 /* backup q->clg and q->loss_model */ 979 old_clg = q->clg; 980 old_loss_model = q->loss_model; 981 982 if (tb[TCA_NETEM_LOSS]) { 983 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]); 984 if (ret) { 985 q->loss_model = old_loss_model; 986 q->clg = old_clg; 987 goto unlock; 988 } 989 } else { 990 q->loss_model = CLG_RANDOM; 991 } 992 993 if (delay_dist) 994 swap(q->delay_dist, delay_dist); 995 if (slot_dist) 996 swap(q->slot_dist, slot_dist); 997 sch->limit = qopt->limit; 998 999 q->latency = PSCHED_TICKS2NS(qopt->latency); 1000 q->jitter = PSCHED_TICKS2NS(qopt->jitter); 1001 q->limit = qopt->limit; 1002 q->gap = qopt->gap; 1003 q->counter = 0; 1004 q->loss = qopt->loss; 1005 q->duplicate = qopt->duplicate; 1006 1007 /* for compatibility with earlier versions. 1008 * if gap is set, need to assume 100% probability 1009 */ 1010 if (q->gap) 1011 q->reorder = ~0; 1012 1013 if (tb[TCA_NETEM_CORR]) 1014 get_correlation(q, tb[TCA_NETEM_CORR]); 1015 1016 if (tb[TCA_NETEM_REORDER]) 1017 get_reorder(q, tb[TCA_NETEM_REORDER]); 1018 1019 if (tb[TCA_NETEM_CORRUPT]) 1020 get_corrupt(q, tb[TCA_NETEM_CORRUPT]); 1021 1022 if (tb[TCA_NETEM_RATE]) 1023 get_rate(q, tb[TCA_NETEM_RATE]); 1024 1025 if (tb[TCA_NETEM_RATE64]) 1026 q->rate = max_t(u64, q->rate, 1027 nla_get_u64(tb[TCA_NETEM_RATE64])); 1028 1029 if (tb[TCA_NETEM_LATENCY64]) 1030 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]); 1031 1032 if (tb[TCA_NETEM_JITTER64]) 1033 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]); 1034 1035 if (tb[TCA_NETEM_ECN]) 1036 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]); 1037 1038 if (tb[TCA_NETEM_SLOT]) 1039 get_slot(q, tb[TCA_NETEM_SLOT]); 1040 1041 /* capping jitter to the range acceptable by tabledist() */ 1042 q->jitter = min_t(s64, abs(q->jitter), INT_MAX); 1043 1044unlock: 1045 sch_tree_unlock(sch); 1046 1047table_free: 1048 dist_free(delay_dist); 1049 dist_free(slot_dist); 1050 return ret; 1051} 1052 1053static int netem_init(struct Qdisc *sch, struct nlattr *opt, 1054 struct netlink_ext_ack *extack) 1055{ 1056 struct netem_sched_data *q = qdisc_priv(sch); 1057 int ret; 1058 1059 qdisc_watchdog_init(&q->watchdog, sch); 1060 1061 if (!opt) 1062 return -EINVAL; 1063 1064 q->loss_model = CLG_RANDOM; 1065 ret = netem_change(sch, opt, extack); 1066 if (ret) 1067 pr_info("netem: change failed\n"); 1068 return ret; 1069} 1070 1071static void netem_destroy(struct Qdisc *sch) 1072{ 1073 struct netem_sched_data *q = qdisc_priv(sch); 1074 1075 qdisc_watchdog_cancel(&q->watchdog); 1076 if (q->qdisc) 1077 qdisc_put(q->qdisc); 1078 dist_free(q->delay_dist); 1079 dist_free(q->slot_dist); 1080} 1081 1082static int dump_loss_model(const struct netem_sched_data *q, 1083 struct sk_buff *skb) 1084{ 1085 struct nlattr *nest; 1086 1087 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS); 1088 if (nest == NULL) 1089 goto nla_put_failure; 1090 1091 switch (q->loss_model) { 1092 case CLG_RANDOM: 1093 /* legacy loss model */ 1094 nla_nest_cancel(skb, nest); 1095 return 0; /* no data */ 1096 1097 case CLG_4_STATES: { 1098 struct tc_netem_gimodel gi = { 1099 .p13 = q->clg.a1, 1100 .p31 = q->clg.a2, 1101 .p32 = q->clg.a3, 1102 .p14 = q->clg.a4, 1103 .p23 = q->clg.a5, 1104 }; 1105 1106 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi)) 1107 goto nla_put_failure; 1108 break; 1109 } 1110 case CLG_GILB_ELL: { 1111 struct tc_netem_gemodel ge = { 1112 .p = q->clg.a1, 1113 .r = q->clg.a2, 1114 .h = q->clg.a3, 1115 .k1 = q->clg.a4, 1116 }; 1117 1118 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge)) 1119 goto nla_put_failure; 1120 break; 1121 } 1122 } 1123 1124 nla_nest_end(skb, nest); 1125 return 0; 1126 1127nla_put_failure: 1128 nla_nest_cancel(skb, nest); 1129 return -1; 1130} 1131 1132static int netem_dump(struct Qdisc *sch, struct sk_buff *skb) 1133{ 1134 const struct netem_sched_data *q = qdisc_priv(sch); 1135 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb); 1136 struct tc_netem_qopt qopt; 1137 struct tc_netem_corr cor; 1138 struct tc_netem_reorder reorder; 1139 struct tc_netem_corrupt corrupt; 1140 struct tc_netem_rate rate; 1141 struct tc_netem_slot slot; 1142 1143 qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency), 1144 UINT_MAX); 1145 qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter), 1146 UINT_MAX); 1147 qopt.limit = q->limit; 1148 qopt.loss = q->loss; 1149 qopt.gap = q->gap; 1150 qopt.duplicate = q->duplicate; 1151 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt)) 1152 goto nla_put_failure; 1153 1154 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency)) 1155 goto nla_put_failure; 1156 1157 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter)) 1158 goto nla_put_failure; 1159 1160 cor.delay_corr = q->delay_cor.rho; 1161 cor.loss_corr = q->loss_cor.rho; 1162 cor.dup_corr = q->dup_cor.rho; 1163 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor)) 1164 goto nla_put_failure; 1165 1166 reorder.probability = q->reorder; 1167 reorder.correlation = q->reorder_cor.rho; 1168 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder)) 1169 goto nla_put_failure; 1170 1171 corrupt.probability = q->corrupt; 1172 corrupt.correlation = q->corrupt_cor.rho; 1173 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt)) 1174 goto nla_put_failure; 1175 1176 if (q->rate >= (1ULL << 32)) { 1177 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate, 1178 TCA_NETEM_PAD)) 1179 goto nla_put_failure; 1180 rate.rate = ~0U; 1181 } else { 1182 rate.rate = q->rate; 1183 } 1184 rate.packet_overhead = q->packet_overhead; 1185 rate.cell_size = q->cell_size; 1186 rate.cell_overhead = q->cell_overhead; 1187 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate)) 1188 goto nla_put_failure; 1189 1190 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn)) 1191 goto nla_put_failure; 1192 1193 if (dump_loss_model(q, skb) != 0) 1194 goto nla_put_failure; 1195 1196 if (q->slot_config.min_delay | q->slot_config.max_delay | 1197 q->slot_config.dist_jitter) { 1198 slot = q->slot_config; 1199 if (slot.max_packets == INT_MAX) 1200 slot.max_packets = 0; 1201 if (slot.max_bytes == INT_MAX) 1202 slot.max_bytes = 0; 1203 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot)) 1204 goto nla_put_failure; 1205 } 1206 1207 return nla_nest_end(skb, nla); 1208 1209nla_put_failure: 1210 nlmsg_trim(skb, nla); 1211 return -1; 1212} 1213 1214static int netem_dump_class(struct Qdisc *sch, unsigned long cl, 1215 struct sk_buff *skb, struct tcmsg *tcm) 1216{ 1217 struct netem_sched_data *q = qdisc_priv(sch); 1218 1219 if (cl != 1 || !q->qdisc) /* only one class */ 1220 return -ENOENT; 1221 1222 tcm->tcm_handle |= TC_H_MIN(1); 1223 tcm->tcm_info = q->qdisc->handle; 1224 1225 return 0; 1226} 1227 1228static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, 1229 struct Qdisc **old, struct netlink_ext_ack *extack) 1230{ 1231 struct netem_sched_data *q = qdisc_priv(sch); 1232 1233 *old = qdisc_replace(sch, new, &q->qdisc); 1234 return 0; 1235} 1236 1237static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg) 1238{ 1239 struct netem_sched_data *q = qdisc_priv(sch); 1240 return q->qdisc; 1241} 1242 1243static unsigned long netem_find(struct Qdisc *sch, u32 classid) 1244{ 1245 return 1; 1246} 1247 1248static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker) 1249{ 1250 if (!walker->stop) { 1251 if (walker->count >= walker->skip) 1252 if (walker->fn(sch, 1, walker) < 0) { 1253 walker->stop = 1; 1254 return; 1255 } 1256 walker->count++; 1257 } 1258} 1259 1260static const struct Qdisc_class_ops netem_class_ops = { 1261 .graft = netem_graft, 1262 .leaf = netem_leaf, 1263 .find = netem_find, 1264 .walk = netem_walk, 1265 .dump = netem_dump_class, 1266}; 1267 1268static struct Qdisc_ops netem_qdisc_ops __read_mostly = { 1269 .id = "netem", 1270 .cl_ops = &netem_class_ops, 1271 .priv_size = sizeof(struct netem_sched_data), 1272 .enqueue = netem_enqueue, 1273 .dequeue = netem_dequeue, 1274 .peek = qdisc_peek_dequeued, 1275 .init = netem_init, 1276 .reset = netem_reset, 1277 .destroy = netem_destroy, 1278 .change = netem_change, 1279 .dump = netem_dump, 1280 .owner = THIS_MODULE, 1281}; 1282 1283 1284static int __init netem_module_init(void) 1285{ 1286 pr_info("netem: version " VERSION "\n"); 1287 return register_qdisc(&netem_qdisc_ops); 1288} 1289static void __exit netem_module_exit(void) 1290{ 1291 unregister_qdisc(&netem_qdisc_ops); 1292} 1293module_init(netem_module_init) 1294module_exit(netem_module_exit) 1295MODULE_LICENSE("GPL"); 1296