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/gso.h>
25 #include <net/netlink.h>
26 #include <net/pkt_sched.h>
27 #include <net/inet_ecn.h>
28
29 #define VERSION "1.3"
30
31 /* Network Emulation Queuing algorithm.
32 ====================================
33
34 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
35 Network Emulation Tool
36 [2] Luigi Rizzo, DummyNet for FreeBSD
37
38 ----------------------------------------------------------------
39
40 This started out as a simple way to delay outgoing packets to
41 test TCP but has grown to include most of the functionality
42 of a full blown network emulator like NISTnet. It can delay
43 packets and add random jitter (and correlation). The random
44 distribution can be loaded from a table as well to provide
45 normal, Pareto, or experimental curves. Packet loss,
46 duplication, and reordering can also be emulated.
47
48 This qdisc does not do classification that can be handled in
49 layering other disciplines. It does not need to do bandwidth
50 control either since that can be handled by using token
51 bucket or other rate control.
52
53 Correlated Loss Generator models
54
55 Added generation of correlated loss according to the
56 "Gilbert-Elliot" model, a 4-state markov model.
57
58 References:
59 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
60 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
61 and intuitive loss model for packet networks and its implementation
62 in the Netem module in the Linux kernel", available in [1]
63
64 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
65 Fabio Ludovici <fabio.ludovici at yahoo.it>
66 */
67
68 struct disttable {
69 u32 size;
70 s16 table[];
71 };
72
73 struct netem_sched_data {
74 /* internal t(ime)fifo qdisc uses t_root and sch->limit */
75 struct rb_root t_root;
76
77 /* a linear queue; reduces rbtree rebalancing when jitter is low */
78 struct sk_buff *t_head;
79 struct sk_buff *t_tail;
80
81 /* optional qdisc for classful handling (NULL at netem init) */
82 struct Qdisc *qdisc;
83
84 struct qdisc_watchdog watchdog;
85
86 s64 latency;
87 s64 jitter;
88
89 u32 loss;
90 u32 ecn;
91 u32 limit;
92 u32 counter;
93 u32 gap;
94 u32 duplicate;
95 u32 reorder;
96 u32 corrupt;
97 u64 rate;
98 s32 packet_overhead;
99 u32 cell_size;
100 struct reciprocal_value cell_size_reciprocal;
101 s32 cell_overhead;
102
103 struct crndstate {
104 u32 last;
105 u32 rho;
106 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
107
108 struct prng {
109 u64 seed;
110 struct rnd_state prng_state;
111 } prng;
112
113 struct disttable *delay_dist;
114
115 enum {
116 CLG_RANDOM,
117 CLG_4_STATES,
118 CLG_GILB_ELL,
119 } loss_model;
120
121 enum {
122 TX_IN_GAP_PERIOD = 1,
123 TX_IN_BURST_PERIOD,
124 LOST_IN_GAP_PERIOD,
125 LOST_IN_BURST_PERIOD,
126 } _4_state_model;
127
128 enum {
129 GOOD_STATE = 1,
130 BAD_STATE,
131 } GE_state_model;
132
133 /* Correlated Loss Generation models */
134 struct clgstate {
135 /* state of the Markov chain */
136 u8 state;
137
138 /* 4-states and Gilbert-Elliot models */
139 u32 a1; /* p13 for 4-states or p for GE */
140 u32 a2; /* p31 for 4-states or r for GE */
141 u32 a3; /* p32 for 4-states or h for GE */
142 u32 a4; /* p14 for 4-states or 1-k for GE */
143 u32 a5; /* p23 used only in 4-states */
144 } clg;
145
146 struct tc_netem_slot slot_config;
147 struct slotstate {
148 u64 slot_next;
149 s32 packets_left;
150 s32 bytes_left;
151 } slot;
152
153 struct disttable *slot_dist;
154 };
155
156 /* Time stamp put into socket buffer control block
157 * Only valid when skbs are in our internal t(ime)fifo queue.
158 *
159 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
160 * and skb->next & skb->prev are scratch space for a qdisc,
161 * we save skb->tstamp value in skb->cb[] before destroying it.
162 */
163 struct netem_skb_cb {
164 u64 time_to_send;
165 };
166
netem_skb_cb(struct sk_buff * skb)167 static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
168 {
169 /* we assume we can use skb next/prev/tstamp as storage for rb_node */
170 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
171 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
172 }
173
174 /* init_crandom - initialize correlated random number generator
175 * Use entropy source for initial seed.
176 */
init_crandom(struct crndstate * state,unsigned long rho)177 static void init_crandom(struct crndstate *state, unsigned long rho)
178 {
179 state->rho = rho;
180 state->last = get_random_u32();
181 }
182
183 /* get_crandom - correlated random number generator
184 * Next number depends on last value.
185 * rho is scaled to avoid floating point.
186 */
get_crandom(struct crndstate * state,struct prng * p)187 static u32 get_crandom(struct crndstate *state, struct prng *p)
188 {
189 u64 value, rho;
190 unsigned long answer;
191 struct rnd_state *s = &p->prng_state;
192
193 if (!state || state->rho == 0) /* no correlation */
194 return prandom_u32_state(s);
195
196 value = prandom_u32_state(s);
197 rho = (u64)state->rho + 1;
198 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
199 state->last = answer;
200 return answer;
201 }
202
203 /* loss_4state - 4-state model loss generator
204 * Generates losses according to the 4-state Markov chain adopted in
205 * the GI (General and Intuitive) loss model.
206 */
loss_4state(struct netem_sched_data * q)207 static bool loss_4state(struct netem_sched_data *q)
208 {
209 struct clgstate *clg = &q->clg;
210 u32 rnd = prandom_u32_state(&q->prng.prng_state);
211
212 /*
213 * Makes a comparison between rnd and the transition
214 * probabilities outgoing from the current state, then decides the
215 * next state and if the next packet has to be transmitted or lost.
216 * The four states correspond to:
217 * TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
218 * LOST_IN_GAP_PERIOD => isolated losses within a gap period
219 * LOST_IN_BURST_PERIOD => lost packets within a burst period
220 * TX_IN_BURST_PERIOD => successfully transmitted packets within a burst period
221 */
222 switch (clg->state) {
223 case TX_IN_GAP_PERIOD:
224 if (rnd < clg->a4) {
225 clg->state = LOST_IN_GAP_PERIOD;
226 return true;
227 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
228 clg->state = LOST_IN_BURST_PERIOD;
229 return true;
230 } else if (clg->a1 + clg->a4 < rnd) {
231 clg->state = TX_IN_GAP_PERIOD;
232 }
233
234 break;
235 case TX_IN_BURST_PERIOD:
236 if (rnd < clg->a5) {
237 clg->state = LOST_IN_BURST_PERIOD;
238 return true;
239 } else {
240 clg->state = TX_IN_BURST_PERIOD;
241 }
242
243 break;
244 case LOST_IN_BURST_PERIOD:
245 if (rnd < clg->a3)
246 clg->state = TX_IN_BURST_PERIOD;
247 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
248 clg->state = TX_IN_GAP_PERIOD;
249 } else if (clg->a2 + clg->a3 < rnd) {
250 clg->state = LOST_IN_BURST_PERIOD;
251 return true;
252 }
253 break;
254 case LOST_IN_GAP_PERIOD:
255 clg->state = TX_IN_GAP_PERIOD;
256 break;
257 }
258
259 return false;
260 }
261
262 /* loss_gilb_ell - Gilbert-Elliot model loss generator
263 * Generates losses according to the Gilbert-Elliot loss model or
264 * its special cases (Gilbert or Simple Gilbert)
265 *
266 * Makes a comparison between random number and the transition
267 * probabilities outgoing from the current state, then decides the
268 * next state. A second random number is extracted and the comparison
269 * with the loss probability of the current state decides if the next
270 * packet will be transmitted or lost.
271 */
loss_gilb_ell(struct netem_sched_data * q)272 static bool loss_gilb_ell(struct netem_sched_data *q)
273 {
274 struct clgstate *clg = &q->clg;
275 struct rnd_state *s = &q->prng.prng_state;
276
277 switch (clg->state) {
278 case GOOD_STATE:
279 if (prandom_u32_state(s) < clg->a1)
280 clg->state = BAD_STATE;
281 if (prandom_u32_state(s) < clg->a4)
282 return true;
283 break;
284 case BAD_STATE:
285 if (prandom_u32_state(s) < clg->a2)
286 clg->state = GOOD_STATE;
287 if (prandom_u32_state(s) > clg->a3)
288 return true;
289 }
290
291 return false;
292 }
293
loss_event(struct netem_sched_data * q)294 static bool loss_event(struct netem_sched_data *q)
295 {
296 switch (q->loss_model) {
297 case CLG_RANDOM:
298 /* Random packet drop 0 => none, ~0 => all */
299 return q->loss && q->loss >= get_crandom(&q->loss_cor, &q->prng);
300
301 case CLG_4_STATES:
302 /* 4state loss model algorithm (used also for GI model)
303 * Extracts a value from the markov 4 state 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_4state(q);
308
309 case CLG_GILB_ELL:
310 /* Gilbert-Elliot loss model algorithm
311 * Extracts a value from the Gilbert-Elliot loss generator,
312 * if it is 1 drops a packet and if needed writes the event in
313 * the kernel logs
314 */
315 return loss_gilb_ell(q);
316 }
317
318 return false; /* not reached */
319 }
320
321
322 /* tabledist - return a pseudo-randomly distributed value with mean mu and
323 * std deviation sigma. Uses table lookup to approximate the desired
324 * distribution, and a uniformly-distributed pseudo-random source.
325 */
tabledist(s64 mu,s32 sigma,struct crndstate * state,struct prng * prng,const struct disttable * dist)326 static s64 tabledist(s64 mu, s32 sigma,
327 struct crndstate *state,
328 struct prng *prng,
329 const struct disttable *dist)
330 {
331 s64 x;
332 long t;
333 u32 rnd;
334
335 if (sigma == 0)
336 return mu;
337
338 rnd = get_crandom(state, prng);
339
340 /* default uniform distribution */
341 if (dist == NULL)
342 return ((rnd % (2 * (u32)sigma)) + mu) - sigma;
343
344 t = dist->table[rnd % dist->size];
345 x = (sigma % NETEM_DIST_SCALE) * t;
346 if (x >= 0)
347 x += NETEM_DIST_SCALE/2;
348 else
349 x -= NETEM_DIST_SCALE/2;
350
351 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
352 }
353
packet_time_ns(u64 len,const struct netem_sched_data * q)354 static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
355 {
356 len += q->packet_overhead;
357
358 if (q->cell_size) {
359 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
360
361 if (len > cells * q->cell_size) /* extra cell needed for remainder */
362 cells++;
363 len = cells * (q->cell_size + q->cell_overhead);
364 }
365
366 return div64_u64(len * NSEC_PER_SEC, q->rate);
367 }
368
tfifo_reset(struct Qdisc * sch)369 static void tfifo_reset(struct Qdisc *sch)
370 {
371 struct netem_sched_data *q = qdisc_priv(sch);
372 struct rb_node *p = rb_first(&q->t_root);
373
374 while (p) {
375 struct sk_buff *skb = rb_to_skb(p);
376
377 p = rb_next(p);
378 rb_erase(&skb->rbnode, &q->t_root);
379 rtnl_kfree_skbs(skb, skb);
380 }
381
382 rtnl_kfree_skbs(q->t_head, q->t_tail);
383 q->t_head = NULL;
384 q->t_tail = NULL;
385 }
386
tfifo_enqueue(struct sk_buff * nskb,struct Qdisc * sch)387 static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
388 {
389 struct netem_sched_data *q = qdisc_priv(sch);
390 u64 tnext = netem_skb_cb(nskb)->time_to_send;
391
392 if (!q->t_tail || tnext >= netem_skb_cb(q->t_tail)->time_to_send) {
393 if (q->t_tail)
394 q->t_tail->next = nskb;
395 else
396 q->t_head = nskb;
397 q->t_tail = nskb;
398 } else {
399 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
400
401 while (*p) {
402 struct sk_buff *skb;
403
404 parent = *p;
405 skb = rb_to_skb(parent);
406 if (tnext >= netem_skb_cb(skb)->time_to_send)
407 p = &parent->rb_right;
408 else
409 p = &parent->rb_left;
410 }
411 rb_link_node(&nskb->rbnode, parent, p);
412 rb_insert_color(&nskb->rbnode, &q->t_root);
413 }
414 sch->q.qlen++;
415 }
416
417 /* netem can't properly corrupt a megapacket (like we get from GSO), so instead
418 * when we statistically choose to corrupt one, we instead segment it, returning
419 * the first packet to be corrupted, and re-enqueue the remaining frames
420 */
netem_segment(struct sk_buff * skb,struct Qdisc * sch,struct sk_buff ** to_free)421 static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
422 struct sk_buff **to_free)
423 {
424 struct sk_buff *segs;
425 netdev_features_t features = netif_skb_features(skb);
426
427 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
428
429 if (IS_ERR_OR_NULL(segs)) {
430 qdisc_drop(skb, sch, to_free);
431 return NULL;
432 }
433 consume_skb(skb);
434 return segs;
435 }
436
437 /*
438 * Insert one skb into qdisc.
439 * Note: parent depends on return value to account for queue length.
440 * NET_XMIT_DROP: queue length didn't change.
441 * NET_XMIT_SUCCESS: one skb was queued.
442 */
netem_enqueue(struct sk_buff * skb,struct Qdisc * sch,struct sk_buff ** to_free)443 static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
444 struct sk_buff **to_free)
445 {
446 struct netem_sched_data *q = qdisc_priv(sch);
447 /* We don't fill cb now as skb_unshare() may invalidate it */
448 struct netem_skb_cb *cb;
449 struct sk_buff *skb2 = NULL;
450 struct sk_buff *segs = NULL;
451 unsigned int prev_len = qdisc_pkt_len(skb);
452 int count = 1;
453
454 /* Do not fool qdisc_drop_all() */
455 skb->prev = NULL;
456
457 /* Random duplication */
458 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor, &q->prng))
459 ++count;
460
461 /* Drop packet? */
462 if (loss_event(q)) {
463 if (q->ecn && INET_ECN_set_ce(skb))
464 qdisc_qstats_drop(sch); /* mark packet */
465 else
466 --count;
467 }
468 if (count == 0) {
469 qdisc_qstats_drop(sch);
470 __qdisc_drop(skb, to_free);
471 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
472 }
473
474 /* If a delay is expected, orphan the skb. (orphaning usually takes
475 * place at TX completion time, so _before_ the link transit delay)
476 */
477 if (q->latency || q->jitter || q->rate)
478 skb_orphan_partial(skb);
479
480 /*
481 * If we need to duplicate packet, then clone it before
482 * original is modified.
483 */
484 if (count > 1)
485 skb2 = skb_clone(skb, GFP_ATOMIC);
486
487 /*
488 * Randomized packet corruption.
489 * Make copy if needed since we are modifying
490 * If packet is going to be hardware checksummed, then
491 * do it now in software before we mangle it.
492 */
493 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor, &q->prng)) {
494 if (skb_is_gso(skb)) {
495 skb = netem_segment(skb, sch, to_free);
496 if (!skb)
497 goto finish_segs;
498
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[get_random_u32_below(skb_headlen(skb))] ^=
517 1<<get_random_u32_below(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 if (skb2)
525 __qdisc_drop(skb2, to_free);
526 return NET_XMIT_DROP;
527 }
528
529 /*
530 * If doing duplication then re-insert at top of the
531 * qdisc tree, since parent queuer expects that only one
532 * skb will be queued.
533 */
534 if (skb2) {
535 struct Qdisc *rootq = qdisc_root_bh(sch);
536 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
537
538 q->duplicate = 0;
539 rootq->enqueue(skb2, rootq, to_free);
540 q->duplicate = dupsave;
541 skb2 = NULL;
542 }
543
544 qdisc_qstats_backlog_inc(sch, skb);
545
546 cb = netem_skb_cb(skb);
547 if (q->gap == 0 || /* not doing reordering */
548 q->counter < q->gap - 1 || /* inside last reordering gap */
549 q->reorder < get_crandom(&q->reorder_cor, &q->prng)) {
550 u64 now;
551 s64 delay;
552
553 delay = tabledist(q->latency, q->jitter,
554 &q->delay_cor, &q->prng, q->delay_dist);
555
556 now = ktime_get_ns();
557
558 if (q->rate) {
559 struct netem_skb_cb *last = NULL;
560
561 if (sch->q.tail)
562 last = netem_skb_cb(sch->q.tail);
563 if (q->t_root.rb_node) {
564 struct sk_buff *t_skb;
565 struct netem_skb_cb *t_last;
566
567 t_skb = skb_rb_last(&q->t_root);
568 t_last = netem_skb_cb(t_skb);
569 if (!last ||
570 t_last->time_to_send > last->time_to_send)
571 last = t_last;
572 }
573 if (q->t_tail) {
574 struct netem_skb_cb *t_last =
575 netem_skb_cb(q->t_tail);
576
577 if (!last ||
578 t_last->time_to_send > last->time_to_send)
579 last = t_last;
580 }
581
582 if (last) {
583 /*
584 * Last packet in queue is reference point (now),
585 * calculate this time bonus and subtract
586 * from delay.
587 */
588 delay -= last->time_to_send - now;
589 delay = max_t(s64, 0, delay);
590 now = last->time_to_send;
591 }
592
593 delay += packet_time_ns(qdisc_pkt_len(skb), q);
594 }
595
596 cb->time_to_send = now + delay;
597 ++q->counter;
598 tfifo_enqueue(skb, sch);
599 } else {
600 /*
601 * Do re-ordering by putting one out of N packets at the front
602 * of the queue.
603 */
604 cb->time_to_send = ktime_get_ns();
605 q->counter = 0;
606
607 __qdisc_enqueue_head(skb, &sch->q);
608 sch->qstats.requeues++;
609 }
610
611 finish_segs:
612 if (skb2)
613 __qdisc_drop(skb2, to_free);
614
615 if (segs) {
616 unsigned int len, last_len;
617 int rc, nb;
618
619 len = skb ? skb->len : 0;
620 nb = skb ? 1 : 0;
621
622 while (segs) {
623 skb2 = segs->next;
624 skb_mark_not_on_list(segs);
625 qdisc_skb_cb(segs)->pkt_len = segs->len;
626 last_len = segs->len;
627 rc = qdisc_enqueue(segs, sch, to_free);
628 if (rc != NET_XMIT_SUCCESS) {
629 if (net_xmit_drop_count(rc))
630 qdisc_qstats_drop(sch);
631 } else {
632 nb++;
633 len += last_len;
634 }
635 segs = skb2;
636 }
637 /* Parent qdiscs accounted for 1 skb of size @prev_len */
638 qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
639 } else if (!skb) {
640 return NET_XMIT_DROP;
641 }
642 return NET_XMIT_SUCCESS;
643 }
644
645 /* Delay the next round with a new future slot with a
646 * correct number of bytes and packets.
647 */
648
get_slot_next(struct netem_sched_data * q,u64 now)649 static void get_slot_next(struct netem_sched_data *q, u64 now)
650 {
651 s64 next_delay;
652
653 if (!q->slot_dist)
654 next_delay = q->slot_config.min_delay +
655 (get_random_u32() *
656 (q->slot_config.max_delay -
657 q->slot_config.min_delay) >> 32);
658 else
659 next_delay = tabledist(q->slot_config.dist_delay,
660 (s32)(q->slot_config.dist_jitter),
661 NULL, &q->prng, q->slot_dist);
662
663 q->slot.slot_next = now + next_delay;
664 q->slot.packets_left = q->slot_config.max_packets;
665 q->slot.bytes_left = q->slot_config.max_bytes;
666 }
667
netem_peek(struct netem_sched_data * q)668 static struct sk_buff *netem_peek(struct netem_sched_data *q)
669 {
670 struct sk_buff *skb = skb_rb_first(&q->t_root);
671 u64 t1, t2;
672
673 if (!skb)
674 return q->t_head;
675 if (!q->t_head)
676 return skb;
677
678 t1 = netem_skb_cb(skb)->time_to_send;
679 t2 = netem_skb_cb(q->t_head)->time_to_send;
680 if (t1 < t2)
681 return skb;
682 return q->t_head;
683 }
684
netem_erase_head(struct netem_sched_data * q,struct sk_buff * skb)685 static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb)
686 {
687 if (skb == q->t_head) {
688 q->t_head = skb->next;
689 if (!q->t_head)
690 q->t_tail = NULL;
691 } else {
692 rb_erase(&skb->rbnode, &q->t_root);
693 }
694 }
695
netem_dequeue(struct Qdisc * sch)696 static struct sk_buff *netem_dequeue(struct Qdisc *sch)
697 {
698 struct netem_sched_data *q = qdisc_priv(sch);
699 struct sk_buff *skb;
700
701 tfifo_dequeue:
702 skb = __qdisc_dequeue_head(&sch->q);
703 if (skb) {
704 qdisc_qstats_backlog_dec(sch, skb);
705 deliver:
706 qdisc_bstats_update(sch, skb);
707 return skb;
708 }
709 skb = netem_peek(q);
710 if (skb) {
711 u64 time_to_send;
712 u64 now = ktime_get_ns();
713
714 /* if more time remaining? */
715 time_to_send = netem_skb_cb(skb)->time_to_send;
716 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
717 get_slot_next(q, now);
718
719 if (time_to_send <= now && q->slot.slot_next <= now) {
720 netem_erase_head(q, skb);
721 sch->q.qlen--;
722 qdisc_qstats_backlog_dec(sch, skb);
723 skb->next = NULL;
724 skb->prev = NULL;
725 /* skb->dev shares skb->rbnode area,
726 * we need to restore its value.
727 */
728 skb->dev = qdisc_dev(sch);
729
730 if (q->slot.slot_next) {
731 q->slot.packets_left--;
732 q->slot.bytes_left -= qdisc_pkt_len(skb);
733 if (q->slot.packets_left <= 0 ||
734 q->slot.bytes_left <= 0)
735 get_slot_next(q, now);
736 }
737
738 if (q->qdisc) {
739 unsigned int pkt_len = qdisc_pkt_len(skb);
740 struct sk_buff *to_free = NULL;
741 int err;
742
743 err = qdisc_enqueue(skb, q->qdisc, &to_free);
744 kfree_skb_list(to_free);
745 if (err != NET_XMIT_SUCCESS &&
746 net_xmit_drop_count(err)) {
747 qdisc_qstats_drop(sch);
748 qdisc_tree_reduce_backlog(sch, 1,
749 pkt_len);
750 }
751 goto tfifo_dequeue;
752 }
753 goto deliver;
754 }
755
756 if (q->qdisc) {
757 skb = q->qdisc->ops->dequeue(q->qdisc);
758 if (skb)
759 goto deliver;
760 }
761
762 qdisc_watchdog_schedule_ns(&q->watchdog,
763 max(time_to_send,
764 q->slot.slot_next));
765 }
766
767 if (q->qdisc) {
768 skb = q->qdisc->ops->dequeue(q->qdisc);
769 if (skb)
770 goto deliver;
771 }
772 return NULL;
773 }
774
netem_reset(struct Qdisc * sch)775 static void netem_reset(struct Qdisc *sch)
776 {
777 struct netem_sched_data *q = qdisc_priv(sch);
778
779 qdisc_reset_queue(sch);
780 tfifo_reset(sch);
781 if (q->qdisc)
782 qdisc_reset(q->qdisc);
783 qdisc_watchdog_cancel(&q->watchdog);
784 }
785
dist_free(struct disttable * d)786 static void dist_free(struct disttable *d)
787 {
788 kvfree(d);
789 }
790
791 /*
792 * Distribution data is a variable size payload containing
793 * signed 16 bit values.
794 */
795
get_dist_table(struct disttable ** tbl,const struct nlattr * attr)796 static int get_dist_table(struct disttable **tbl, const struct nlattr *attr)
797 {
798 size_t n = nla_len(attr)/sizeof(__s16);
799 const __s16 *data = nla_data(attr);
800 struct disttable *d;
801 int i;
802
803 if (!n || n > NETEM_DIST_MAX)
804 return -EINVAL;
805
806 d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
807 if (!d)
808 return -ENOMEM;
809
810 d->size = n;
811 for (i = 0; i < n; i++)
812 d->table[i] = data[i];
813
814 *tbl = d;
815 return 0;
816 }
817
get_slot(struct netem_sched_data * q,const struct nlattr * attr)818 static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
819 {
820 const struct tc_netem_slot *c = nla_data(attr);
821
822 q->slot_config = *c;
823 if (q->slot_config.max_packets == 0)
824 q->slot_config.max_packets = INT_MAX;
825 if (q->slot_config.max_bytes == 0)
826 q->slot_config.max_bytes = INT_MAX;
827
828 /* capping dist_jitter to the range acceptable by tabledist() */
829 q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter));
830
831 q->slot.packets_left = q->slot_config.max_packets;
832 q->slot.bytes_left = q->slot_config.max_bytes;
833 if (q->slot_config.min_delay | q->slot_config.max_delay |
834 q->slot_config.dist_jitter)
835 q->slot.slot_next = ktime_get_ns();
836 else
837 q->slot.slot_next = 0;
838 }
839
get_correlation(struct netem_sched_data * q,const struct nlattr * attr)840 static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
841 {
842 const struct tc_netem_corr *c = nla_data(attr);
843
844 init_crandom(&q->delay_cor, c->delay_corr);
845 init_crandom(&q->loss_cor, c->loss_corr);
846 init_crandom(&q->dup_cor, c->dup_corr);
847 }
848
get_reorder(struct netem_sched_data * q,const struct nlattr * attr)849 static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
850 {
851 const struct tc_netem_reorder *r = nla_data(attr);
852
853 q->reorder = r->probability;
854 init_crandom(&q->reorder_cor, r->correlation);
855 }
856
get_corrupt(struct netem_sched_data * q,const struct nlattr * attr)857 static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
858 {
859 const struct tc_netem_corrupt *r = nla_data(attr);
860
861 q->corrupt = r->probability;
862 init_crandom(&q->corrupt_cor, r->correlation);
863 }
864
get_rate(struct netem_sched_data * q,const struct nlattr * attr)865 static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
866 {
867 const struct tc_netem_rate *r = nla_data(attr);
868
869 q->rate = r->rate;
870 q->packet_overhead = r->packet_overhead;
871 q->cell_size = r->cell_size;
872 q->cell_overhead = r->cell_overhead;
873 if (q->cell_size)
874 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
875 else
876 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
877 }
878
get_loss_clg(struct netem_sched_data * q,const struct nlattr * attr)879 static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
880 {
881 const struct nlattr *la;
882 int rem;
883
884 nla_for_each_nested(la, attr, rem) {
885 u16 type = nla_type(la);
886
887 switch (type) {
888 case NETEM_LOSS_GI: {
889 const struct tc_netem_gimodel *gi = nla_data(la);
890
891 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
892 pr_info("netem: incorrect gi model size\n");
893 return -EINVAL;
894 }
895
896 q->loss_model = CLG_4_STATES;
897
898 q->clg.state = TX_IN_GAP_PERIOD;
899 q->clg.a1 = gi->p13;
900 q->clg.a2 = gi->p31;
901 q->clg.a3 = gi->p32;
902 q->clg.a4 = gi->p14;
903 q->clg.a5 = gi->p23;
904 break;
905 }
906
907 case NETEM_LOSS_GE: {
908 const struct tc_netem_gemodel *ge = nla_data(la);
909
910 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
911 pr_info("netem: incorrect ge model size\n");
912 return -EINVAL;
913 }
914
915 q->loss_model = CLG_GILB_ELL;
916 q->clg.state = GOOD_STATE;
917 q->clg.a1 = ge->p;
918 q->clg.a2 = ge->r;
919 q->clg.a3 = ge->h;
920 q->clg.a4 = ge->k1;
921 break;
922 }
923
924 default:
925 pr_info("netem: unknown loss type %u\n", type);
926 return -EINVAL;
927 }
928 }
929
930 return 0;
931 }
932
933 static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
934 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
935 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
936 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
937 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
938 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
939 [TCA_NETEM_ECN] = { .type = NLA_U32 },
940 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
941 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
942 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
943 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
944 [TCA_NETEM_PRNG_SEED] = { .type = NLA_U64 },
945 };
946
parse_attr(struct nlattr * tb[],int maxtype,struct nlattr * nla,const struct nla_policy * policy,int len)947 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
948 const struct nla_policy *policy, int len)
949 {
950 int nested_len = nla_len(nla) - NLA_ALIGN(len);
951
952 if (nested_len < 0) {
953 pr_info("netem: invalid attributes len %d\n", nested_len);
954 return -EINVAL;
955 }
956
957 if (nested_len >= nla_attr_size(0))
958 return nla_parse_deprecated(tb, maxtype,
959 nla_data(nla) + NLA_ALIGN(len),
960 nested_len, policy, NULL);
961
962 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
963 return 0;
964 }
965
966 /* Parse netlink message to set options */
netem_change(struct Qdisc * sch,struct nlattr * opt,struct netlink_ext_ack * extack)967 static int netem_change(struct Qdisc *sch, struct nlattr *opt,
968 struct netlink_ext_ack *extack)
969 {
970 struct netem_sched_data *q = qdisc_priv(sch);
971 struct nlattr *tb[TCA_NETEM_MAX + 1];
972 struct disttable *delay_dist = NULL;
973 struct disttable *slot_dist = NULL;
974 struct tc_netem_qopt *qopt;
975 struct clgstate old_clg;
976 int old_loss_model = CLG_RANDOM;
977 int ret;
978
979 qopt = nla_data(opt);
980 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
981 if (ret < 0)
982 return ret;
983
984 if (tb[TCA_NETEM_DELAY_DIST]) {
985 ret = get_dist_table(&delay_dist, tb[TCA_NETEM_DELAY_DIST]);
986 if (ret)
987 goto table_free;
988 }
989
990 if (tb[TCA_NETEM_SLOT_DIST]) {
991 ret = get_dist_table(&slot_dist, tb[TCA_NETEM_SLOT_DIST]);
992 if (ret)
993 goto table_free;
994 }
995
996 sch_tree_lock(sch);
997 /* backup q->clg and q->loss_model */
998 old_clg = q->clg;
999 old_loss_model = q->loss_model;
1000
1001 if (tb[TCA_NETEM_LOSS]) {
1002 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
1003 if (ret) {
1004 q->loss_model = old_loss_model;
1005 q->clg = old_clg;
1006 goto unlock;
1007 }
1008 } else {
1009 q->loss_model = CLG_RANDOM;
1010 }
1011
1012 if (delay_dist)
1013 swap(q->delay_dist, delay_dist);
1014 if (slot_dist)
1015 swap(q->slot_dist, slot_dist);
1016 sch->limit = qopt->limit;
1017
1018 q->latency = PSCHED_TICKS2NS(qopt->latency);
1019 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
1020 q->limit = qopt->limit;
1021 q->gap = qopt->gap;
1022 q->counter = 0;
1023 q->loss = qopt->loss;
1024 q->duplicate = qopt->duplicate;
1025
1026 /* for compatibility with earlier versions.
1027 * if gap is set, need to assume 100% probability
1028 */
1029 if (q->gap)
1030 q->reorder = ~0;
1031
1032 if (tb[TCA_NETEM_CORR])
1033 get_correlation(q, tb[TCA_NETEM_CORR]);
1034
1035 if (tb[TCA_NETEM_REORDER])
1036 get_reorder(q, tb[TCA_NETEM_REORDER]);
1037
1038 if (tb[TCA_NETEM_CORRUPT])
1039 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
1040
1041 if (tb[TCA_NETEM_RATE])
1042 get_rate(q, tb[TCA_NETEM_RATE]);
1043
1044 if (tb[TCA_NETEM_RATE64])
1045 q->rate = max_t(u64, q->rate,
1046 nla_get_u64(tb[TCA_NETEM_RATE64]));
1047
1048 if (tb[TCA_NETEM_LATENCY64])
1049 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
1050
1051 if (tb[TCA_NETEM_JITTER64])
1052 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
1053
1054 if (tb[TCA_NETEM_ECN])
1055 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
1056
1057 if (tb[TCA_NETEM_SLOT])
1058 get_slot(q, tb[TCA_NETEM_SLOT]);
1059
1060 /* capping jitter to the range acceptable by tabledist() */
1061 q->jitter = min_t(s64, abs(q->jitter), INT_MAX);
1062
1063 if (tb[TCA_NETEM_PRNG_SEED])
1064 q->prng.seed = nla_get_u64(tb[TCA_NETEM_PRNG_SEED]);
1065 else
1066 q->prng.seed = get_random_u64();
1067 prandom_seed_state(&q->prng.prng_state, q->prng.seed);
1068
1069 unlock:
1070 sch_tree_unlock(sch);
1071
1072 table_free:
1073 dist_free(delay_dist);
1074 dist_free(slot_dist);
1075 return ret;
1076 }
1077
netem_init(struct Qdisc * sch,struct nlattr * opt,struct netlink_ext_ack * extack)1078 static int netem_init(struct Qdisc *sch, struct nlattr *opt,
1079 struct netlink_ext_ack *extack)
1080 {
1081 struct netem_sched_data *q = qdisc_priv(sch);
1082 int ret;
1083
1084 qdisc_watchdog_init(&q->watchdog, sch);
1085
1086 if (!opt)
1087 return -EINVAL;
1088
1089 q->loss_model = CLG_RANDOM;
1090 ret = netem_change(sch, opt, extack);
1091 if (ret)
1092 pr_info("netem: change failed\n");
1093 return ret;
1094 }
1095
netem_destroy(struct Qdisc * sch)1096 static void netem_destroy(struct Qdisc *sch)
1097 {
1098 struct netem_sched_data *q = qdisc_priv(sch);
1099
1100 qdisc_watchdog_cancel(&q->watchdog);
1101 if (q->qdisc)
1102 qdisc_put(q->qdisc);
1103 dist_free(q->delay_dist);
1104 dist_free(q->slot_dist);
1105 }
1106
dump_loss_model(const struct netem_sched_data * q,struct sk_buff * skb)1107 static int dump_loss_model(const struct netem_sched_data *q,
1108 struct sk_buff *skb)
1109 {
1110 struct nlattr *nest;
1111
1112 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
1113 if (nest == NULL)
1114 goto nla_put_failure;
1115
1116 switch (q->loss_model) {
1117 case CLG_RANDOM:
1118 /* legacy loss model */
1119 nla_nest_cancel(skb, nest);
1120 return 0; /* no data */
1121
1122 case CLG_4_STATES: {
1123 struct tc_netem_gimodel gi = {
1124 .p13 = q->clg.a1,
1125 .p31 = q->clg.a2,
1126 .p32 = q->clg.a3,
1127 .p14 = q->clg.a4,
1128 .p23 = q->clg.a5,
1129 };
1130
1131 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1132 goto nla_put_failure;
1133 break;
1134 }
1135 case CLG_GILB_ELL: {
1136 struct tc_netem_gemodel ge = {
1137 .p = q->clg.a1,
1138 .r = q->clg.a2,
1139 .h = q->clg.a3,
1140 .k1 = q->clg.a4,
1141 };
1142
1143 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1144 goto nla_put_failure;
1145 break;
1146 }
1147 }
1148
1149 nla_nest_end(skb, nest);
1150 return 0;
1151
1152 nla_put_failure:
1153 nla_nest_cancel(skb, nest);
1154 return -1;
1155 }
1156
netem_dump(struct Qdisc * sch,struct sk_buff * skb)1157 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1158 {
1159 const struct netem_sched_data *q = qdisc_priv(sch);
1160 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1161 struct tc_netem_qopt qopt;
1162 struct tc_netem_corr cor;
1163 struct tc_netem_reorder reorder;
1164 struct tc_netem_corrupt corrupt;
1165 struct tc_netem_rate rate;
1166 struct tc_netem_slot slot;
1167
1168 qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency),
1169 UINT_MAX);
1170 qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter),
1171 UINT_MAX);
1172 qopt.limit = q->limit;
1173 qopt.loss = q->loss;
1174 qopt.gap = q->gap;
1175 qopt.duplicate = q->duplicate;
1176 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1177 goto nla_put_failure;
1178
1179 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1180 goto nla_put_failure;
1181
1182 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1183 goto nla_put_failure;
1184
1185 cor.delay_corr = q->delay_cor.rho;
1186 cor.loss_corr = q->loss_cor.rho;
1187 cor.dup_corr = q->dup_cor.rho;
1188 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1189 goto nla_put_failure;
1190
1191 reorder.probability = q->reorder;
1192 reorder.correlation = q->reorder_cor.rho;
1193 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1194 goto nla_put_failure;
1195
1196 corrupt.probability = q->corrupt;
1197 corrupt.correlation = q->corrupt_cor.rho;
1198 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1199 goto nla_put_failure;
1200
1201 if (q->rate >= (1ULL << 32)) {
1202 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1203 TCA_NETEM_PAD))
1204 goto nla_put_failure;
1205 rate.rate = ~0U;
1206 } else {
1207 rate.rate = q->rate;
1208 }
1209 rate.packet_overhead = q->packet_overhead;
1210 rate.cell_size = q->cell_size;
1211 rate.cell_overhead = q->cell_overhead;
1212 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1213 goto nla_put_failure;
1214
1215 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1216 goto nla_put_failure;
1217
1218 if (dump_loss_model(q, skb) != 0)
1219 goto nla_put_failure;
1220
1221 if (q->slot_config.min_delay | q->slot_config.max_delay |
1222 q->slot_config.dist_jitter) {
1223 slot = q->slot_config;
1224 if (slot.max_packets == INT_MAX)
1225 slot.max_packets = 0;
1226 if (slot.max_bytes == INT_MAX)
1227 slot.max_bytes = 0;
1228 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1229 goto nla_put_failure;
1230 }
1231
1232 if (nla_put_u64_64bit(skb, TCA_NETEM_PRNG_SEED, q->prng.seed,
1233 TCA_NETEM_PAD))
1234 goto nla_put_failure;
1235
1236 return nla_nest_end(skb, nla);
1237
1238 nla_put_failure:
1239 nlmsg_trim(skb, nla);
1240 return -1;
1241 }
1242
netem_dump_class(struct Qdisc * sch,unsigned long cl,struct sk_buff * skb,struct tcmsg * tcm)1243 static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1244 struct sk_buff *skb, struct tcmsg *tcm)
1245 {
1246 struct netem_sched_data *q = qdisc_priv(sch);
1247
1248 if (cl != 1 || !q->qdisc) /* only one class */
1249 return -ENOENT;
1250
1251 tcm->tcm_handle |= TC_H_MIN(1);
1252 tcm->tcm_info = q->qdisc->handle;
1253
1254 return 0;
1255 }
1256
netem_graft(struct Qdisc * sch,unsigned long arg,struct Qdisc * new,struct Qdisc ** old,struct netlink_ext_ack * extack)1257 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1258 struct Qdisc **old, struct netlink_ext_ack *extack)
1259 {
1260 struct netem_sched_data *q = qdisc_priv(sch);
1261
1262 *old = qdisc_replace(sch, new, &q->qdisc);
1263 return 0;
1264 }
1265
netem_leaf(struct Qdisc * sch,unsigned long arg)1266 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1267 {
1268 struct netem_sched_data *q = qdisc_priv(sch);
1269 return q->qdisc;
1270 }
1271
netem_find(struct Qdisc * sch,u32 classid)1272 static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1273 {
1274 return 1;
1275 }
1276
netem_walk(struct Qdisc * sch,struct qdisc_walker * walker)1277 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1278 {
1279 if (!walker->stop) {
1280 if (!tc_qdisc_stats_dump(sch, 1, walker))
1281 return;
1282 }
1283 }
1284
1285 static const struct Qdisc_class_ops netem_class_ops = {
1286 .graft = netem_graft,
1287 .leaf = netem_leaf,
1288 .find = netem_find,
1289 .walk = netem_walk,
1290 .dump = netem_dump_class,
1291 };
1292
1293 static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1294 .id = "netem",
1295 .cl_ops = &netem_class_ops,
1296 .priv_size = sizeof(struct netem_sched_data),
1297 .enqueue = netem_enqueue,
1298 .dequeue = netem_dequeue,
1299 .peek = qdisc_peek_dequeued,
1300 .init = netem_init,
1301 .reset = netem_reset,
1302 .destroy = netem_destroy,
1303 .change = netem_change,
1304 .dump = netem_dump,
1305 .owner = THIS_MODULE,
1306 };
1307
1308
netem_module_init(void)1309 static int __init netem_module_init(void)
1310 {
1311 pr_info("netem: version " VERSION "\n");
1312 return register_qdisc(&netem_qdisc_ops);
1313 }
netem_module_exit(void)1314 static void __exit netem_module_exit(void)
1315 {
1316 unregister_qdisc(&netem_qdisc_ops);
1317 }
1318 module_init(netem_module_init)
1319 module_exit(netem_module_exit)
1320 MODULE_LICENSE("GPL");
1321