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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[];
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 * (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
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 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
594 finish_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
629 static 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
648 static 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
665 static 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
676 static struct sk_buff *netem_dequeue(struct Qdisc *sch)
677 {
678 struct netem_sched_data *q = qdisc_priv(sch);
679 struct sk_buff *skb;
680
681 tfifo_dequeue:
682 skb = __qdisc_dequeue_head(&sch->q);
683 if (skb) {
684 qdisc_qstats_backlog_dec(sch, skb);
685 deliver:
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 net_xmit_drop_count(err)) {
727 qdisc_qstats_drop(sch);
728 qdisc_tree_reduce_backlog(sch, 1,
729 pkt_len);
730 }
731 goto tfifo_dequeue;
732 }
733 goto deliver;
734 }
735
736 if (q->qdisc) {
737 skb = q->qdisc->ops->dequeue(q->qdisc);
738 if (skb)
739 goto deliver;
740 }
741
742 qdisc_watchdog_schedule_ns(&q->watchdog,
743 max(time_to_send,
744 q->slot.slot_next));
745 }
746
747 if (q->qdisc) {
748 skb = q->qdisc->ops->dequeue(q->qdisc);
749 if (skb)
750 goto deliver;
751 }
752 return NULL;
753 }
754
755 static void netem_reset(struct Qdisc *sch)
756 {
757 struct netem_sched_data *q = qdisc_priv(sch);
758
759 qdisc_reset_queue(sch);
760 tfifo_reset(sch);
761 if (q->qdisc)
762 qdisc_reset(q->qdisc);
763 qdisc_watchdog_cancel(&q->watchdog);
764 }
765
766 static void dist_free(struct disttable *d)
767 {
768 kvfree(d);
769 }
770
771 /*
772 * Distribution data is a variable size payload containing
773 * signed 16 bit values.
774 */
775
776 static int get_dist_table(struct Qdisc *sch, struct disttable **tbl,
777 const struct nlattr *attr)
778 {
779 size_t n = nla_len(attr)/sizeof(__s16);
780 const __s16 *data = nla_data(attr);
781 spinlock_t *root_lock;
782 struct disttable *d;
783 int i;
784
785 if (!n || n > NETEM_DIST_MAX)
786 return -EINVAL;
787
788 d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL);
789 if (!d)
790 return -ENOMEM;
791
792 d->size = n;
793 for (i = 0; i < n; i++)
794 d->table[i] = data[i];
795
796 root_lock = qdisc_root_sleeping_lock(sch);
797
798 spin_lock_bh(root_lock);
799 swap(*tbl, d);
800 spin_unlock_bh(root_lock);
801
802 dist_free(d);
803 return 0;
804 }
805
806 static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
807 {
808 const struct tc_netem_slot *c = nla_data(attr);
809
810 q->slot_config = *c;
811 if (q->slot_config.max_packets == 0)
812 q->slot_config.max_packets = INT_MAX;
813 if (q->slot_config.max_bytes == 0)
814 q->slot_config.max_bytes = INT_MAX;
815
816 /* capping dist_jitter to the range acceptable by tabledist() */
817 q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter));
818
819 q->slot.packets_left = q->slot_config.max_packets;
820 q->slot.bytes_left = q->slot_config.max_bytes;
821 if (q->slot_config.min_delay | q->slot_config.max_delay |
822 q->slot_config.dist_jitter)
823 q->slot.slot_next = ktime_get_ns();
824 else
825 q->slot.slot_next = 0;
826 }
827
828 static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
829 {
830 const struct tc_netem_corr *c = nla_data(attr);
831
832 init_crandom(&q->delay_cor, c->delay_corr);
833 init_crandom(&q->loss_cor, c->loss_corr);
834 init_crandom(&q->dup_cor, c->dup_corr);
835 }
836
837 static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
838 {
839 const struct tc_netem_reorder *r = nla_data(attr);
840
841 q->reorder = r->probability;
842 init_crandom(&q->reorder_cor, r->correlation);
843 }
844
845 static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
846 {
847 const struct tc_netem_corrupt *r = nla_data(attr);
848
849 q->corrupt = r->probability;
850 init_crandom(&q->corrupt_cor, r->correlation);
851 }
852
853 static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
854 {
855 const struct tc_netem_rate *r = nla_data(attr);
856
857 q->rate = r->rate;
858 q->packet_overhead = r->packet_overhead;
859 q->cell_size = r->cell_size;
860 q->cell_overhead = r->cell_overhead;
861 if (q->cell_size)
862 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
863 else
864 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
865 }
866
867 static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
868 {
869 const struct nlattr *la;
870 int rem;
871
872 nla_for_each_nested(la, attr, rem) {
873 u16 type = nla_type(la);
874
875 switch (type) {
876 case NETEM_LOSS_GI: {
877 const struct tc_netem_gimodel *gi = nla_data(la);
878
879 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
880 pr_info("netem: incorrect gi model size\n");
881 return -EINVAL;
882 }
883
884 q->loss_model = CLG_4_STATES;
885
886 q->clg.state = TX_IN_GAP_PERIOD;
887 q->clg.a1 = gi->p13;
888 q->clg.a2 = gi->p31;
889 q->clg.a3 = gi->p32;
890 q->clg.a4 = gi->p14;
891 q->clg.a5 = gi->p23;
892 break;
893 }
894
895 case NETEM_LOSS_GE: {
896 const struct tc_netem_gemodel *ge = nla_data(la);
897
898 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
899 pr_info("netem: incorrect ge model size\n");
900 return -EINVAL;
901 }
902
903 q->loss_model = CLG_GILB_ELL;
904 q->clg.state = GOOD_STATE;
905 q->clg.a1 = ge->p;
906 q->clg.a2 = ge->r;
907 q->clg.a3 = ge->h;
908 q->clg.a4 = ge->k1;
909 break;
910 }
911
912 default:
913 pr_info("netem: unknown loss type %u\n", type);
914 return -EINVAL;
915 }
916 }
917
918 return 0;
919 }
920
921 static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
922 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
923 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
924 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
925 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
926 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
927 [TCA_NETEM_ECN] = { .type = NLA_U32 },
928 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
929 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
930 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
931 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
932 };
933
934 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
935 const struct nla_policy *policy, int len)
936 {
937 int nested_len = nla_len(nla) - NLA_ALIGN(len);
938
939 if (nested_len < 0) {
940 pr_info("netem: invalid attributes len %d\n", nested_len);
941 return -EINVAL;
942 }
943
944 if (nested_len >= nla_attr_size(0))
945 return nla_parse_deprecated(tb, maxtype,
946 nla_data(nla) + NLA_ALIGN(len),
947 nested_len, policy, NULL);
948
949 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
950 return 0;
951 }
952
953 /* Parse netlink message to set options */
954 static int netem_change(struct Qdisc *sch, struct nlattr *opt,
955 struct netlink_ext_ack *extack)
956 {
957 struct netem_sched_data *q = qdisc_priv(sch);
958 struct nlattr *tb[TCA_NETEM_MAX + 1];
959 struct tc_netem_qopt *qopt;
960 struct clgstate old_clg;
961 int old_loss_model = CLG_RANDOM;
962 int ret;
963
964 if (opt == NULL)
965 return -EINVAL;
966
967 qopt = nla_data(opt);
968 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
969 if (ret < 0)
970 return ret;
971
972 /* backup q->clg and q->loss_model */
973 old_clg = q->clg;
974 old_loss_model = q->loss_model;
975
976 if (tb[TCA_NETEM_LOSS]) {
977 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
978 if (ret) {
979 q->loss_model = old_loss_model;
980 return ret;
981 }
982 } else {
983 q->loss_model = CLG_RANDOM;
984 }
985
986 if (tb[TCA_NETEM_DELAY_DIST]) {
987 ret = get_dist_table(sch, &q->delay_dist,
988 tb[TCA_NETEM_DELAY_DIST]);
989 if (ret)
990 goto get_table_failure;
991 }
992
993 if (tb[TCA_NETEM_SLOT_DIST]) {
994 ret = get_dist_table(sch, &q->slot_dist,
995 tb[TCA_NETEM_SLOT_DIST]);
996 if (ret)
997 goto get_table_failure;
998 }
999
1000 sch->limit = qopt->limit;
1001
1002 q->latency = PSCHED_TICKS2NS(qopt->latency);
1003 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
1004 q->limit = qopt->limit;
1005 q->gap = qopt->gap;
1006 q->counter = 0;
1007 q->loss = qopt->loss;
1008 q->duplicate = qopt->duplicate;
1009
1010 /* for compatibility with earlier versions.
1011 * if gap is set, need to assume 100% probability
1012 */
1013 if (q->gap)
1014 q->reorder = ~0;
1015
1016 if (tb[TCA_NETEM_CORR])
1017 get_correlation(q, tb[TCA_NETEM_CORR]);
1018
1019 if (tb[TCA_NETEM_REORDER])
1020 get_reorder(q, tb[TCA_NETEM_REORDER]);
1021
1022 if (tb[TCA_NETEM_CORRUPT])
1023 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
1024
1025 if (tb[TCA_NETEM_RATE])
1026 get_rate(q, tb[TCA_NETEM_RATE]);
1027
1028 if (tb[TCA_NETEM_RATE64])
1029 q->rate = max_t(u64, q->rate,
1030 nla_get_u64(tb[TCA_NETEM_RATE64]));
1031
1032 if (tb[TCA_NETEM_LATENCY64])
1033 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
1034
1035 if (tb[TCA_NETEM_JITTER64])
1036 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
1037
1038 if (tb[TCA_NETEM_ECN])
1039 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
1040
1041 if (tb[TCA_NETEM_SLOT])
1042 get_slot(q, tb[TCA_NETEM_SLOT]);
1043
1044 /* capping jitter to the range acceptable by tabledist() */
1045 q->jitter = min_t(s64, abs(q->jitter), INT_MAX);
1046
1047 return ret;
1048
1049 get_table_failure:
1050 /* recover clg and loss_model, in case of
1051 * q->clg and q->loss_model were modified
1052 * in get_loss_clg()
1053 */
1054 q->clg = old_clg;
1055 q->loss_model = old_loss_model;
1056 return ret;
1057 }
1058
1059 static int netem_init(struct Qdisc *sch, struct nlattr *opt,
1060 struct netlink_ext_ack *extack)
1061 {
1062 struct netem_sched_data *q = qdisc_priv(sch);
1063 int ret;
1064
1065 qdisc_watchdog_init(&q->watchdog, sch);
1066
1067 if (!opt)
1068 return -EINVAL;
1069
1070 q->loss_model = CLG_RANDOM;
1071 ret = netem_change(sch, opt, extack);
1072 if (ret)
1073 pr_info("netem: change failed\n");
1074 return ret;
1075 }
1076
1077 static void netem_destroy(struct Qdisc *sch)
1078 {
1079 struct netem_sched_data *q = qdisc_priv(sch);
1080
1081 qdisc_watchdog_cancel(&q->watchdog);
1082 if (q->qdisc)
1083 qdisc_put(q->qdisc);
1084 dist_free(q->delay_dist);
1085 dist_free(q->slot_dist);
1086 }
1087
1088 static int dump_loss_model(const struct netem_sched_data *q,
1089 struct sk_buff *skb)
1090 {
1091 struct nlattr *nest;
1092
1093 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
1094 if (nest == NULL)
1095 goto nla_put_failure;
1096
1097 switch (q->loss_model) {
1098 case CLG_RANDOM:
1099 /* legacy loss model */
1100 nla_nest_cancel(skb, nest);
1101 return 0; /* no data */
1102
1103 case CLG_4_STATES: {
1104 struct tc_netem_gimodel gi = {
1105 .p13 = q->clg.a1,
1106 .p31 = q->clg.a2,
1107 .p32 = q->clg.a3,
1108 .p14 = q->clg.a4,
1109 .p23 = q->clg.a5,
1110 };
1111
1112 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1113 goto nla_put_failure;
1114 break;
1115 }
1116 case CLG_GILB_ELL: {
1117 struct tc_netem_gemodel ge = {
1118 .p = q->clg.a1,
1119 .r = q->clg.a2,
1120 .h = q->clg.a3,
1121 .k1 = q->clg.a4,
1122 };
1123
1124 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1125 goto nla_put_failure;
1126 break;
1127 }
1128 }
1129
1130 nla_nest_end(skb, nest);
1131 return 0;
1132
1133 nla_put_failure:
1134 nla_nest_cancel(skb, nest);
1135 return -1;
1136 }
1137
1138 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1139 {
1140 const struct netem_sched_data *q = qdisc_priv(sch);
1141 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1142 struct tc_netem_qopt qopt;
1143 struct tc_netem_corr cor;
1144 struct tc_netem_reorder reorder;
1145 struct tc_netem_corrupt corrupt;
1146 struct tc_netem_rate rate;
1147 struct tc_netem_slot slot;
1148
1149 qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency),
1150 UINT_MAX);
1151 qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter),
1152 UINT_MAX);
1153 qopt.limit = q->limit;
1154 qopt.loss = q->loss;
1155 qopt.gap = q->gap;
1156 qopt.duplicate = q->duplicate;
1157 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1158 goto nla_put_failure;
1159
1160 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1161 goto nla_put_failure;
1162
1163 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1164 goto nla_put_failure;
1165
1166 cor.delay_corr = q->delay_cor.rho;
1167 cor.loss_corr = q->loss_cor.rho;
1168 cor.dup_corr = q->dup_cor.rho;
1169 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1170 goto nla_put_failure;
1171
1172 reorder.probability = q->reorder;
1173 reorder.correlation = q->reorder_cor.rho;
1174 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1175 goto nla_put_failure;
1176
1177 corrupt.probability = q->corrupt;
1178 corrupt.correlation = q->corrupt_cor.rho;
1179 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1180 goto nla_put_failure;
1181
1182 if (q->rate >= (1ULL << 32)) {
1183 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1184 TCA_NETEM_PAD))
1185 goto nla_put_failure;
1186 rate.rate = ~0U;
1187 } else {
1188 rate.rate = q->rate;
1189 }
1190 rate.packet_overhead = q->packet_overhead;
1191 rate.cell_size = q->cell_size;
1192 rate.cell_overhead = q->cell_overhead;
1193 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1194 goto nla_put_failure;
1195
1196 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1197 goto nla_put_failure;
1198
1199 if (dump_loss_model(q, skb) != 0)
1200 goto nla_put_failure;
1201
1202 if (q->slot_config.min_delay | q->slot_config.max_delay |
1203 q->slot_config.dist_jitter) {
1204 slot = q->slot_config;
1205 if (slot.max_packets == INT_MAX)
1206 slot.max_packets = 0;
1207 if (slot.max_bytes == INT_MAX)
1208 slot.max_bytes = 0;
1209 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1210 goto nla_put_failure;
1211 }
1212
1213 return nla_nest_end(skb, nla);
1214
1215 nla_put_failure:
1216 nlmsg_trim(skb, nla);
1217 return -1;
1218 }
1219
1220 static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1221 struct sk_buff *skb, struct tcmsg *tcm)
1222 {
1223 struct netem_sched_data *q = qdisc_priv(sch);
1224
1225 if (cl != 1 || !q->qdisc) /* only one class */
1226 return -ENOENT;
1227
1228 tcm->tcm_handle |= TC_H_MIN(1);
1229 tcm->tcm_info = q->qdisc->handle;
1230
1231 return 0;
1232 }
1233
1234 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1235 struct Qdisc **old, struct netlink_ext_ack *extack)
1236 {
1237 struct netem_sched_data *q = qdisc_priv(sch);
1238
1239 *old = qdisc_replace(sch, new, &q->qdisc);
1240 return 0;
1241 }
1242
1243 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1244 {
1245 struct netem_sched_data *q = qdisc_priv(sch);
1246 return q->qdisc;
1247 }
1248
1249 static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1250 {
1251 return 1;
1252 }
1253
1254 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1255 {
1256 if (!walker->stop) {
1257 if (walker->count >= walker->skip)
1258 if (walker->fn(sch, 1, walker) < 0) {
1259 walker->stop = 1;
1260 return;
1261 }
1262 walker->count++;
1263 }
1264 }
1265
1266 static const struct Qdisc_class_ops netem_class_ops = {
1267 .graft = netem_graft,
1268 .leaf = netem_leaf,
1269 .find = netem_find,
1270 .walk = netem_walk,
1271 .dump = netem_dump_class,
1272 };
1273
1274 static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1275 .id = "netem",
1276 .cl_ops = &netem_class_ops,
1277 .priv_size = sizeof(struct netem_sched_data),
1278 .enqueue = netem_enqueue,
1279 .dequeue = netem_dequeue,
1280 .peek = qdisc_peek_dequeued,
1281 .init = netem_init,
1282 .reset = netem_reset,
1283 .destroy = netem_destroy,
1284 .change = netem_change,
1285 .dump = netem_dump,
1286 .owner = THIS_MODULE,
1287 };
1288
1289
1290 static int __init netem_module_init(void)
1291 {
1292 pr_info("netem: version " VERSION "\n");
1293 return register_qdisc(&netem_qdisc_ops);
1294 }
1295 static void __exit netem_module_exit(void)
1296 {
1297 unregister_qdisc(&netem_qdisc_ops);
1298 }
1299 module_init(netem_module_init)
1300 module_exit(netem_module_exit)
1301 MODULE_LICENSE("GPL");
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