Loading...
1/*
2 * net/sched/sch_netem.c Network emulator
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License.
8 *
9 * Many of the algorithms and ideas for this came from
10 * NIST Net which is not copyrighted.
11 *
12 * Authors: Stephen Hemminger <shemminger@osdl.org>
13 * Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
14 */
15
16#include <linux/mm.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/types.h>
20#include <linux/kernel.h>
21#include <linux/errno.h>
22#include <linux/skbuff.h>
23#include <linux/vmalloc.h>
24#include <linux/rtnetlink.h>
25#include <linux/reciprocal_div.h>
26#include <linux/rbtree.h>
27
28#include <net/netlink.h>
29#include <net/pkt_sched.h>
30#include <net/inet_ecn.h>
31
32#define VERSION "1.3"
33
34/* Network Emulation Queuing algorithm.
35 ====================================
36
37 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
38 Network Emulation Tool
39 [2] Luigi Rizzo, DummyNet for FreeBSD
40
41 ----------------------------------------------------------------
42
43 This started out as a simple way to delay outgoing packets to
44 test TCP but has grown to include most of the functionality
45 of a full blown network emulator like NISTnet. It can delay
46 packets and add random jitter (and correlation). The random
47 distribution can be loaded from a table as well to provide
48 normal, Pareto, or experimental curves. Packet loss,
49 duplication, and reordering can also be emulated.
50
51 This qdisc does not do classification that can be handled in
52 layering other disciplines. It does not need to do bandwidth
53 control either since that can be handled by using token
54 bucket or other rate control.
55
56 Correlated Loss Generator models
57
58 Added generation of correlated loss according to the
59 "Gilbert-Elliot" model, a 4-state markov model.
60
61 References:
62 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
63 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
64 and intuitive loss model for packet networks and its implementation
65 in the Netem module in the Linux kernel", available in [1]
66
67 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
68 Fabio Ludovici <fabio.ludovici at yahoo.it>
69*/
70
71struct netem_sched_data {
72 /* internal t(ime)fifo qdisc uses t_root and sch->limit */
73 struct rb_root t_root;
74
75 /* optional qdisc for classful handling (NULL at netem init) */
76 struct Qdisc *qdisc;
77
78 struct qdisc_watchdog watchdog;
79
80 s64 latency;
81 s64 jitter;
82
83 u32 loss;
84 u32 ecn;
85 u32 limit;
86 u32 counter;
87 u32 gap;
88 u32 duplicate;
89 u32 reorder;
90 u32 corrupt;
91 u64 rate;
92 s32 packet_overhead;
93 u32 cell_size;
94 struct reciprocal_value cell_size_reciprocal;
95 s32 cell_overhead;
96
97 struct crndstate {
98 u32 last;
99 u32 rho;
100 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
101
102 struct disttable {
103 u32 size;
104 s16 table[0];
105 } *delay_dist;
106
107 enum {
108 CLG_RANDOM,
109 CLG_4_STATES,
110 CLG_GILB_ELL,
111 } loss_model;
112
113 enum {
114 TX_IN_GAP_PERIOD = 1,
115 TX_IN_BURST_PERIOD,
116 LOST_IN_GAP_PERIOD,
117 LOST_IN_BURST_PERIOD,
118 } _4_state_model;
119
120 enum {
121 GOOD_STATE = 1,
122 BAD_STATE,
123 } GE_state_model;
124
125 /* Correlated Loss Generation models */
126 struct clgstate {
127 /* state of the Markov chain */
128 u8 state;
129
130 /* 4-states and Gilbert-Elliot models */
131 u32 a1; /* p13 for 4-states or p for GE */
132 u32 a2; /* p31 for 4-states or r for GE */
133 u32 a3; /* p32 for 4-states or h for GE */
134 u32 a4; /* p14 for 4-states or 1-k for GE */
135 u32 a5; /* p23 used only in 4-states */
136 } clg;
137
138 struct tc_netem_slot slot_config;
139 struct slotstate {
140 u64 slot_next;
141 s32 packets_left;
142 s32 bytes_left;
143 } slot;
144
145};
146
147/* Time stamp put into socket buffer control block
148 * Only valid when skbs are in our internal t(ime)fifo queue.
149 *
150 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
151 * and skb->next & skb->prev are scratch space for a qdisc,
152 * we save skb->tstamp value in skb->cb[] before destroying it.
153 */
154struct netem_skb_cb {
155 u64 time_to_send;
156};
157
158static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
159{
160 /* we assume we can use skb next/prev/tstamp as storage for rb_node */
161 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
162 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
163}
164
165/* init_crandom - initialize correlated random number generator
166 * Use entropy source for initial seed.
167 */
168static void init_crandom(struct crndstate *state, unsigned long rho)
169{
170 state->rho = rho;
171 state->last = prandom_u32();
172}
173
174/* get_crandom - correlated random number generator
175 * Next number depends on last value.
176 * rho is scaled to avoid floating point.
177 */
178static u32 get_crandom(struct crndstate *state)
179{
180 u64 value, rho;
181 unsigned long answer;
182
183 if (state->rho == 0) /* no correlation */
184 return prandom_u32();
185
186 value = prandom_u32();
187 rho = (u64)state->rho + 1;
188 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
189 state->last = answer;
190 return answer;
191}
192
193/* loss_4state - 4-state model loss generator
194 * Generates losses according to the 4-state Markov chain adopted in
195 * the GI (General and Intuitive) loss model.
196 */
197static bool loss_4state(struct netem_sched_data *q)
198{
199 struct clgstate *clg = &q->clg;
200 u32 rnd = prandom_u32();
201
202 /*
203 * Makes a comparison between rnd and the transition
204 * probabilities outgoing from the current state, then decides the
205 * next state and if the next packet has to be transmitted or lost.
206 * The four states correspond to:
207 * TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
208 * LOST_IN_BURST_PERIOD => isolated losses within a gap period
209 * LOST_IN_GAP_PERIOD => lost packets within a burst period
210 * TX_IN_GAP_PERIOD => successfully transmitted packets within a burst period
211 */
212 switch (clg->state) {
213 case TX_IN_GAP_PERIOD:
214 if (rnd < clg->a4) {
215 clg->state = LOST_IN_BURST_PERIOD;
216 return true;
217 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
218 clg->state = LOST_IN_GAP_PERIOD;
219 return true;
220 } else if (clg->a1 + clg->a4 < rnd) {
221 clg->state = TX_IN_GAP_PERIOD;
222 }
223
224 break;
225 case TX_IN_BURST_PERIOD:
226 if (rnd < clg->a5) {
227 clg->state = LOST_IN_GAP_PERIOD;
228 return true;
229 } else {
230 clg->state = TX_IN_BURST_PERIOD;
231 }
232
233 break;
234 case LOST_IN_GAP_PERIOD:
235 if (rnd < clg->a3)
236 clg->state = TX_IN_BURST_PERIOD;
237 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
238 clg->state = TX_IN_GAP_PERIOD;
239 } else if (clg->a2 + clg->a3 < rnd) {
240 clg->state = LOST_IN_GAP_PERIOD;
241 return true;
242 }
243 break;
244 case LOST_IN_BURST_PERIOD:
245 clg->state = TX_IN_GAP_PERIOD;
246 break;
247 }
248
249 return false;
250}
251
252/* loss_gilb_ell - Gilbert-Elliot model loss generator
253 * Generates losses according to the Gilbert-Elliot loss model or
254 * its special cases (Gilbert or Simple Gilbert)
255 *
256 * Makes a comparison between random number and the transition
257 * probabilities outgoing from the current state, then decides the
258 * next state. A second random number is extracted and the comparison
259 * with the loss probability of the current state decides if the next
260 * packet will be transmitted or lost.
261 */
262static bool loss_gilb_ell(struct netem_sched_data *q)
263{
264 struct clgstate *clg = &q->clg;
265
266 switch (clg->state) {
267 case GOOD_STATE:
268 if (prandom_u32() < clg->a1)
269 clg->state = BAD_STATE;
270 if (prandom_u32() < clg->a4)
271 return true;
272 break;
273 case BAD_STATE:
274 if (prandom_u32() < clg->a2)
275 clg->state = GOOD_STATE;
276 if (prandom_u32() > clg->a3)
277 return true;
278 }
279
280 return false;
281}
282
283static bool loss_event(struct netem_sched_data *q)
284{
285 switch (q->loss_model) {
286 case CLG_RANDOM:
287 /* Random packet drop 0 => none, ~0 => all */
288 return q->loss && q->loss >= get_crandom(&q->loss_cor);
289
290 case CLG_4_STATES:
291 /* 4state loss model algorithm (used also for GI model)
292 * Extracts a value from the markov 4 state loss generator,
293 * if it is 1 drops a packet and if needed writes the event in
294 * the kernel logs
295 */
296 return loss_4state(q);
297
298 case CLG_GILB_ELL:
299 /* Gilbert-Elliot loss model algorithm
300 * Extracts a value from the Gilbert-Elliot loss generator,
301 * if it is 1 drops a packet and if needed writes the event in
302 * the kernel logs
303 */
304 return loss_gilb_ell(q);
305 }
306
307 return false; /* not reached */
308}
309
310
311/* tabledist - return a pseudo-randomly distributed value with mean mu and
312 * std deviation sigma. Uses table lookup to approximate the desired
313 * distribution, and a uniformly-distributed pseudo-random source.
314 */
315static s64 tabledist(s64 mu, s32 sigma,
316 struct crndstate *state,
317 const struct disttable *dist)
318{
319 s64 x;
320 long t;
321 u32 rnd;
322
323 if (sigma == 0)
324 return mu;
325
326 rnd = get_crandom(state);
327
328 /* default uniform distribution */
329 if (dist == NULL)
330 return ((rnd % (2 * sigma)) + mu) - sigma;
331
332 t = dist->table[rnd % dist->size];
333 x = (sigma % NETEM_DIST_SCALE) * t;
334 if (x >= 0)
335 x += NETEM_DIST_SCALE/2;
336 else
337 x -= NETEM_DIST_SCALE/2;
338
339 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
340}
341
342static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
343{
344 len += q->packet_overhead;
345
346 if (q->cell_size) {
347 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
348
349 if (len > cells * q->cell_size) /* extra cell needed for remainder */
350 cells++;
351 len = cells * (q->cell_size + q->cell_overhead);
352 }
353
354 return div64_u64(len * NSEC_PER_SEC, q->rate);
355}
356
357static void tfifo_reset(struct Qdisc *sch)
358{
359 struct netem_sched_data *q = qdisc_priv(sch);
360 struct rb_node *p = rb_first(&q->t_root);
361
362 while (p) {
363 struct sk_buff *skb = rb_to_skb(p);
364
365 p = rb_next(p);
366 rb_erase(&skb->rbnode, &q->t_root);
367 rtnl_kfree_skbs(skb, skb);
368 }
369}
370
371static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
372{
373 struct netem_sched_data *q = qdisc_priv(sch);
374 u64 tnext = netem_skb_cb(nskb)->time_to_send;
375 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
376
377 while (*p) {
378 struct sk_buff *skb;
379
380 parent = *p;
381 skb = rb_to_skb(parent);
382 if (tnext >= netem_skb_cb(skb)->time_to_send)
383 p = &parent->rb_right;
384 else
385 p = &parent->rb_left;
386 }
387 rb_link_node(&nskb->rbnode, parent, p);
388 rb_insert_color(&nskb->rbnode, &q->t_root);
389 sch->q.qlen++;
390}
391
392/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
393 * when we statistically choose to corrupt one, we instead segment it, returning
394 * the first packet to be corrupted, and re-enqueue the remaining frames
395 */
396static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
397 struct sk_buff **to_free)
398{
399 struct sk_buff *segs;
400 netdev_features_t features = netif_skb_features(skb);
401
402 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
403
404 if (IS_ERR_OR_NULL(segs)) {
405 qdisc_drop(skb, sch, to_free);
406 return NULL;
407 }
408 consume_skb(skb);
409 return segs;
410}
411
412static void netem_enqueue_skb_head(struct qdisc_skb_head *qh, struct sk_buff *skb)
413{
414 skb->next = qh->head;
415
416 if (!qh->head)
417 qh->tail = skb;
418 qh->head = skb;
419 qh->qlen++;
420}
421
422/*
423 * Insert one skb into qdisc.
424 * Note: parent depends on return value to account for queue length.
425 * NET_XMIT_DROP: queue length didn't change.
426 * NET_XMIT_SUCCESS: one skb was queued.
427 */
428static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
429 struct sk_buff **to_free)
430{
431 struct netem_sched_data *q = qdisc_priv(sch);
432 /* We don't fill cb now as skb_unshare() may invalidate it */
433 struct netem_skb_cb *cb;
434 struct sk_buff *skb2;
435 struct sk_buff *segs = NULL;
436 unsigned int len = 0, last_len, prev_len = qdisc_pkt_len(skb);
437 int nb = 0;
438 int count = 1;
439 int rc = NET_XMIT_SUCCESS;
440
441 /* Random duplication */
442 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
443 ++count;
444
445 /* Drop packet? */
446 if (loss_event(q)) {
447 if (q->ecn && INET_ECN_set_ce(skb))
448 qdisc_qstats_drop(sch); /* mark packet */
449 else
450 --count;
451 }
452 if (count == 0) {
453 qdisc_qstats_drop(sch);
454 __qdisc_drop(skb, to_free);
455 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
456 }
457
458 /* If a delay is expected, orphan the skb. (orphaning usually takes
459 * place at TX completion time, so _before_ the link transit delay)
460 */
461 if (q->latency || q->jitter || q->rate)
462 skb_orphan_partial(skb);
463
464 /*
465 * If we need to duplicate packet, then re-insert at top of the
466 * qdisc tree, since parent queuer expects that only one
467 * skb will be queued.
468 */
469 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
470 struct Qdisc *rootq = qdisc_root(sch);
471 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
472
473 q->duplicate = 0;
474 rootq->enqueue(skb2, rootq, to_free);
475 q->duplicate = dupsave;
476 }
477
478 /*
479 * Randomized packet corruption.
480 * Make copy if needed since we are modifying
481 * If packet is going to be hardware checksummed, then
482 * do it now in software before we mangle it.
483 */
484 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
485 if (skb_is_gso(skb)) {
486 segs = netem_segment(skb, sch, to_free);
487 if (!segs)
488 return NET_XMIT_DROP;
489 } else {
490 segs = skb;
491 }
492
493 skb = segs;
494 segs = segs->next;
495
496 skb = skb_unshare(skb, GFP_ATOMIC);
497 if (unlikely(!skb)) {
498 qdisc_qstats_drop(sch);
499 goto finish_segs;
500 }
501 if (skb->ip_summed == CHECKSUM_PARTIAL &&
502 skb_checksum_help(skb)) {
503 qdisc_drop(skb, sch, to_free);
504 goto finish_segs;
505 }
506
507 skb->data[prandom_u32() % skb_headlen(skb)] ^=
508 1<<(prandom_u32() % 8);
509 }
510
511 if (unlikely(sch->q.qlen >= sch->limit))
512 return qdisc_drop_all(skb, sch, to_free);
513
514 qdisc_qstats_backlog_inc(sch, skb);
515
516 cb = netem_skb_cb(skb);
517 if (q->gap == 0 || /* not doing reordering */
518 q->counter < q->gap - 1 || /* inside last reordering gap */
519 q->reorder < get_crandom(&q->reorder_cor)) {
520 u64 now;
521 s64 delay;
522
523 delay = tabledist(q->latency, q->jitter,
524 &q->delay_cor, q->delay_dist);
525
526 now = ktime_get_ns();
527
528 if (q->rate) {
529 struct netem_skb_cb *last = NULL;
530
531 if (sch->q.tail)
532 last = netem_skb_cb(sch->q.tail);
533 if (q->t_root.rb_node) {
534 struct sk_buff *t_skb;
535 struct netem_skb_cb *t_last;
536
537 t_skb = skb_rb_last(&q->t_root);
538 t_last = netem_skb_cb(t_skb);
539 if (!last ||
540 t_last->time_to_send > last->time_to_send) {
541 last = t_last;
542 }
543 }
544
545 if (last) {
546 /*
547 * Last packet in queue is reference point (now),
548 * calculate this time bonus and subtract
549 * from delay.
550 */
551 delay -= last->time_to_send - now;
552 delay = max_t(s64, 0, delay);
553 now = last->time_to_send;
554 }
555
556 delay += packet_time_ns(qdisc_pkt_len(skb), q);
557 }
558
559 cb->time_to_send = now + delay;
560 ++q->counter;
561 tfifo_enqueue(skb, sch);
562 } else {
563 /*
564 * Do re-ordering by putting one out of N packets at the front
565 * of the queue.
566 */
567 cb->time_to_send = ktime_get_ns();
568 q->counter = 0;
569
570 netem_enqueue_skb_head(&sch->q, skb);
571 sch->qstats.requeues++;
572 }
573
574finish_segs:
575 if (segs) {
576 while (segs) {
577 skb2 = segs->next;
578 segs->next = NULL;
579 qdisc_skb_cb(segs)->pkt_len = segs->len;
580 last_len = segs->len;
581 rc = qdisc_enqueue(segs, sch, to_free);
582 if (rc != NET_XMIT_SUCCESS) {
583 if (net_xmit_drop_count(rc))
584 qdisc_qstats_drop(sch);
585 } else {
586 nb++;
587 len += last_len;
588 }
589 segs = skb2;
590 }
591 sch->q.qlen += nb;
592 if (nb > 1)
593 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
594 }
595 return NET_XMIT_SUCCESS;
596}
597
598/* Delay the next round with a new future slot with a
599 * correct number of bytes and packets.
600 */
601
602static void get_slot_next(struct netem_sched_data *q, u64 now)
603{
604 q->slot.slot_next = now + q->slot_config.min_delay +
605 (prandom_u32() *
606 (q->slot_config.max_delay -
607 q->slot_config.min_delay) >> 32);
608 q->slot.packets_left = q->slot_config.max_packets;
609 q->slot.bytes_left = q->slot_config.max_bytes;
610}
611
612static struct sk_buff *netem_dequeue(struct Qdisc *sch)
613{
614 struct netem_sched_data *q = qdisc_priv(sch);
615 struct sk_buff *skb;
616 struct rb_node *p;
617
618tfifo_dequeue:
619 skb = __qdisc_dequeue_head(&sch->q);
620 if (skb) {
621 qdisc_qstats_backlog_dec(sch, skb);
622deliver:
623 qdisc_bstats_update(sch, skb);
624 return skb;
625 }
626 p = rb_first(&q->t_root);
627 if (p) {
628 u64 time_to_send;
629 u64 now = ktime_get_ns();
630
631 skb = rb_to_skb(p);
632
633 /* if more time remaining? */
634 time_to_send = netem_skb_cb(skb)->time_to_send;
635 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
636 get_slot_next(q, now);
637
638 if (time_to_send <= now && q->slot.slot_next <= now) {
639 rb_erase(p, &q->t_root);
640 sch->q.qlen--;
641 qdisc_qstats_backlog_dec(sch, skb);
642 skb->next = NULL;
643 skb->prev = NULL;
644 /* skb->dev shares skb->rbnode area,
645 * we need to restore its value.
646 */
647 skb->dev = qdisc_dev(sch);
648
649#ifdef CONFIG_NET_CLS_ACT
650 /*
651 * If it's at ingress let's pretend the delay is
652 * from the network (tstamp will be updated).
653 */
654 if (skb->tc_redirected && skb->tc_from_ingress)
655 skb->tstamp = 0;
656#endif
657
658 if (q->slot.slot_next) {
659 q->slot.packets_left--;
660 q->slot.bytes_left -= qdisc_pkt_len(skb);
661 if (q->slot.packets_left <= 0 ||
662 q->slot.bytes_left <= 0)
663 get_slot_next(q, now);
664 }
665
666 if (q->qdisc) {
667 unsigned int pkt_len = qdisc_pkt_len(skb);
668 struct sk_buff *to_free = NULL;
669 int err;
670
671 err = qdisc_enqueue(skb, q->qdisc, &to_free);
672 kfree_skb_list(to_free);
673 if (err != NET_XMIT_SUCCESS &&
674 net_xmit_drop_count(err)) {
675 qdisc_qstats_drop(sch);
676 qdisc_tree_reduce_backlog(sch, 1,
677 pkt_len);
678 }
679 goto tfifo_dequeue;
680 }
681 goto deliver;
682 }
683
684 if (q->qdisc) {
685 skb = q->qdisc->ops->dequeue(q->qdisc);
686 if (skb)
687 goto deliver;
688 }
689
690 qdisc_watchdog_schedule_ns(&q->watchdog,
691 max(time_to_send,
692 q->slot.slot_next));
693 }
694
695 if (q->qdisc) {
696 skb = q->qdisc->ops->dequeue(q->qdisc);
697 if (skb)
698 goto deliver;
699 }
700 return NULL;
701}
702
703static void netem_reset(struct Qdisc *sch)
704{
705 struct netem_sched_data *q = qdisc_priv(sch);
706
707 qdisc_reset_queue(sch);
708 tfifo_reset(sch);
709 if (q->qdisc)
710 qdisc_reset(q->qdisc);
711 qdisc_watchdog_cancel(&q->watchdog);
712}
713
714static void dist_free(struct disttable *d)
715{
716 kvfree(d);
717}
718
719/*
720 * Distribution data is a variable size payload containing
721 * signed 16 bit values.
722 */
723
724static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
725{
726 struct netem_sched_data *q = qdisc_priv(sch);
727 size_t n = nla_len(attr)/sizeof(__s16);
728 const __s16 *data = nla_data(attr);
729 spinlock_t *root_lock;
730 struct disttable *d;
731 int i;
732
733 if (n > NETEM_DIST_MAX)
734 return -EINVAL;
735
736 d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL);
737 if (!d)
738 return -ENOMEM;
739
740 d->size = n;
741 for (i = 0; i < n; i++)
742 d->table[i] = data[i];
743
744 root_lock = qdisc_root_sleeping_lock(sch);
745
746 spin_lock_bh(root_lock);
747 swap(q->delay_dist, d);
748 spin_unlock_bh(root_lock);
749
750 dist_free(d);
751 return 0;
752}
753
754static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
755{
756 const struct tc_netem_slot *c = nla_data(attr);
757
758 q->slot_config = *c;
759 if (q->slot_config.max_packets == 0)
760 q->slot_config.max_packets = INT_MAX;
761 if (q->slot_config.max_bytes == 0)
762 q->slot_config.max_bytes = INT_MAX;
763 q->slot.packets_left = q->slot_config.max_packets;
764 q->slot.bytes_left = q->slot_config.max_bytes;
765 if (q->slot_config.min_delay | q->slot_config.max_delay)
766 q->slot.slot_next = ktime_get_ns();
767 else
768 q->slot.slot_next = 0;
769}
770
771static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
772{
773 const struct tc_netem_corr *c = nla_data(attr);
774
775 init_crandom(&q->delay_cor, c->delay_corr);
776 init_crandom(&q->loss_cor, c->loss_corr);
777 init_crandom(&q->dup_cor, c->dup_corr);
778}
779
780static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
781{
782 const struct tc_netem_reorder *r = nla_data(attr);
783
784 q->reorder = r->probability;
785 init_crandom(&q->reorder_cor, r->correlation);
786}
787
788static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
789{
790 const struct tc_netem_corrupt *r = nla_data(attr);
791
792 q->corrupt = r->probability;
793 init_crandom(&q->corrupt_cor, r->correlation);
794}
795
796static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
797{
798 const struct tc_netem_rate *r = nla_data(attr);
799
800 q->rate = r->rate;
801 q->packet_overhead = r->packet_overhead;
802 q->cell_size = r->cell_size;
803 q->cell_overhead = r->cell_overhead;
804 if (q->cell_size)
805 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
806 else
807 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
808}
809
810static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
811{
812 const struct nlattr *la;
813 int rem;
814
815 nla_for_each_nested(la, attr, rem) {
816 u16 type = nla_type(la);
817
818 switch (type) {
819 case NETEM_LOSS_GI: {
820 const struct tc_netem_gimodel *gi = nla_data(la);
821
822 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
823 pr_info("netem: incorrect gi model size\n");
824 return -EINVAL;
825 }
826
827 q->loss_model = CLG_4_STATES;
828
829 q->clg.state = TX_IN_GAP_PERIOD;
830 q->clg.a1 = gi->p13;
831 q->clg.a2 = gi->p31;
832 q->clg.a3 = gi->p32;
833 q->clg.a4 = gi->p14;
834 q->clg.a5 = gi->p23;
835 break;
836 }
837
838 case NETEM_LOSS_GE: {
839 const struct tc_netem_gemodel *ge = nla_data(la);
840
841 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
842 pr_info("netem: incorrect ge model size\n");
843 return -EINVAL;
844 }
845
846 q->loss_model = CLG_GILB_ELL;
847 q->clg.state = GOOD_STATE;
848 q->clg.a1 = ge->p;
849 q->clg.a2 = ge->r;
850 q->clg.a3 = ge->h;
851 q->clg.a4 = ge->k1;
852 break;
853 }
854
855 default:
856 pr_info("netem: unknown loss type %u\n", type);
857 return -EINVAL;
858 }
859 }
860
861 return 0;
862}
863
864static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
865 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
866 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
867 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
868 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
869 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
870 [TCA_NETEM_ECN] = { .type = NLA_U32 },
871 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
872 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
873 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
874 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
875};
876
877static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
878 const struct nla_policy *policy, int len)
879{
880 int nested_len = nla_len(nla) - NLA_ALIGN(len);
881
882 if (nested_len < 0) {
883 pr_info("netem: invalid attributes len %d\n", nested_len);
884 return -EINVAL;
885 }
886
887 if (nested_len >= nla_attr_size(0))
888 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
889 nested_len, policy, NULL);
890
891 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
892 return 0;
893}
894
895/* Parse netlink message to set options */
896static int netem_change(struct Qdisc *sch, struct nlattr *opt,
897 struct netlink_ext_ack *extack)
898{
899 struct netem_sched_data *q = qdisc_priv(sch);
900 struct nlattr *tb[TCA_NETEM_MAX + 1];
901 struct tc_netem_qopt *qopt;
902 struct clgstate old_clg;
903 int old_loss_model = CLG_RANDOM;
904 int ret;
905
906 if (opt == NULL)
907 return -EINVAL;
908
909 qopt = nla_data(opt);
910 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
911 if (ret < 0)
912 return ret;
913
914 /* backup q->clg and q->loss_model */
915 old_clg = q->clg;
916 old_loss_model = q->loss_model;
917
918 if (tb[TCA_NETEM_LOSS]) {
919 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
920 if (ret) {
921 q->loss_model = old_loss_model;
922 return ret;
923 }
924 } else {
925 q->loss_model = CLG_RANDOM;
926 }
927
928 if (tb[TCA_NETEM_DELAY_DIST]) {
929 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
930 if (ret) {
931 /* recover clg and loss_model, in case of
932 * q->clg and q->loss_model were modified
933 * in get_loss_clg()
934 */
935 q->clg = old_clg;
936 q->loss_model = old_loss_model;
937 return ret;
938 }
939 }
940
941 sch->limit = qopt->limit;
942
943 q->latency = PSCHED_TICKS2NS(qopt->latency);
944 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
945 q->limit = qopt->limit;
946 q->gap = qopt->gap;
947 q->counter = 0;
948 q->loss = qopt->loss;
949 q->duplicate = qopt->duplicate;
950
951 /* for compatibility with earlier versions.
952 * if gap is set, need to assume 100% probability
953 */
954 if (q->gap)
955 q->reorder = ~0;
956
957 if (tb[TCA_NETEM_CORR])
958 get_correlation(q, tb[TCA_NETEM_CORR]);
959
960 if (tb[TCA_NETEM_REORDER])
961 get_reorder(q, tb[TCA_NETEM_REORDER]);
962
963 if (tb[TCA_NETEM_CORRUPT])
964 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
965
966 if (tb[TCA_NETEM_RATE])
967 get_rate(q, tb[TCA_NETEM_RATE]);
968
969 if (tb[TCA_NETEM_RATE64])
970 q->rate = max_t(u64, q->rate,
971 nla_get_u64(tb[TCA_NETEM_RATE64]));
972
973 if (tb[TCA_NETEM_LATENCY64])
974 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
975
976 if (tb[TCA_NETEM_JITTER64])
977 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
978
979 if (tb[TCA_NETEM_ECN])
980 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
981
982 if (tb[TCA_NETEM_SLOT])
983 get_slot(q, tb[TCA_NETEM_SLOT]);
984
985 return ret;
986}
987
988static int netem_init(struct Qdisc *sch, struct nlattr *opt,
989 struct netlink_ext_ack *extack)
990{
991 struct netem_sched_data *q = qdisc_priv(sch);
992 int ret;
993
994 qdisc_watchdog_init(&q->watchdog, sch);
995
996 if (!opt)
997 return -EINVAL;
998
999 q->loss_model = CLG_RANDOM;
1000 ret = netem_change(sch, opt, extack);
1001 if (ret)
1002 pr_info("netem: change failed\n");
1003 return ret;
1004}
1005
1006static void netem_destroy(struct Qdisc *sch)
1007{
1008 struct netem_sched_data *q = qdisc_priv(sch);
1009
1010 qdisc_watchdog_cancel(&q->watchdog);
1011 if (q->qdisc)
1012 qdisc_destroy(q->qdisc);
1013 dist_free(q->delay_dist);
1014}
1015
1016static int dump_loss_model(const struct netem_sched_data *q,
1017 struct sk_buff *skb)
1018{
1019 struct nlattr *nest;
1020
1021 nest = nla_nest_start(skb, TCA_NETEM_LOSS);
1022 if (nest == NULL)
1023 goto nla_put_failure;
1024
1025 switch (q->loss_model) {
1026 case CLG_RANDOM:
1027 /* legacy loss model */
1028 nla_nest_cancel(skb, nest);
1029 return 0; /* no data */
1030
1031 case CLG_4_STATES: {
1032 struct tc_netem_gimodel gi = {
1033 .p13 = q->clg.a1,
1034 .p31 = q->clg.a2,
1035 .p32 = q->clg.a3,
1036 .p14 = q->clg.a4,
1037 .p23 = q->clg.a5,
1038 };
1039
1040 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1041 goto nla_put_failure;
1042 break;
1043 }
1044 case CLG_GILB_ELL: {
1045 struct tc_netem_gemodel ge = {
1046 .p = q->clg.a1,
1047 .r = q->clg.a2,
1048 .h = q->clg.a3,
1049 .k1 = q->clg.a4,
1050 };
1051
1052 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1053 goto nla_put_failure;
1054 break;
1055 }
1056 }
1057
1058 nla_nest_end(skb, nest);
1059 return 0;
1060
1061nla_put_failure:
1062 nla_nest_cancel(skb, nest);
1063 return -1;
1064}
1065
1066static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1067{
1068 const struct netem_sched_data *q = qdisc_priv(sch);
1069 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1070 struct tc_netem_qopt qopt;
1071 struct tc_netem_corr cor;
1072 struct tc_netem_reorder reorder;
1073 struct tc_netem_corrupt corrupt;
1074 struct tc_netem_rate rate;
1075 struct tc_netem_slot slot;
1076
1077 qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency),
1078 UINT_MAX);
1079 qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter),
1080 UINT_MAX);
1081 qopt.limit = q->limit;
1082 qopt.loss = q->loss;
1083 qopt.gap = q->gap;
1084 qopt.duplicate = q->duplicate;
1085 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1086 goto nla_put_failure;
1087
1088 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1089 goto nla_put_failure;
1090
1091 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1092 goto nla_put_failure;
1093
1094 cor.delay_corr = q->delay_cor.rho;
1095 cor.loss_corr = q->loss_cor.rho;
1096 cor.dup_corr = q->dup_cor.rho;
1097 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1098 goto nla_put_failure;
1099
1100 reorder.probability = q->reorder;
1101 reorder.correlation = q->reorder_cor.rho;
1102 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1103 goto nla_put_failure;
1104
1105 corrupt.probability = q->corrupt;
1106 corrupt.correlation = q->corrupt_cor.rho;
1107 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1108 goto nla_put_failure;
1109
1110 if (q->rate >= (1ULL << 32)) {
1111 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1112 TCA_NETEM_PAD))
1113 goto nla_put_failure;
1114 rate.rate = ~0U;
1115 } else {
1116 rate.rate = q->rate;
1117 }
1118 rate.packet_overhead = q->packet_overhead;
1119 rate.cell_size = q->cell_size;
1120 rate.cell_overhead = q->cell_overhead;
1121 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1122 goto nla_put_failure;
1123
1124 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1125 goto nla_put_failure;
1126
1127 if (dump_loss_model(q, skb) != 0)
1128 goto nla_put_failure;
1129
1130 if (q->slot_config.min_delay | q->slot_config.max_delay) {
1131 slot = q->slot_config;
1132 if (slot.max_packets == INT_MAX)
1133 slot.max_packets = 0;
1134 if (slot.max_bytes == INT_MAX)
1135 slot.max_bytes = 0;
1136 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1137 goto nla_put_failure;
1138 }
1139
1140 return nla_nest_end(skb, nla);
1141
1142nla_put_failure:
1143 nlmsg_trim(skb, nla);
1144 return -1;
1145}
1146
1147static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1148 struct sk_buff *skb, struct tcmsg *tcm)
1149{
1150 struct netem_sched_data *q = qdisc_priv(sch);
1151
1152 if (cl != 1 || !q->qdisc) /* only one class */
1153 return -ENOENT;
1154
1155 tcm->tcm_handle |= TC_H_MIN(1);
1156 tcm->tcm_info = q->qdisc->handle;
1157
1158 return 0;
1159}
1160
1161static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1162 struct Qdisc **old, struct netlink_ext_ack *extack)
1163{
1164 struct netem_sched_data *q = qdisc_priv(sch);
1165
1166 *old = qdisc_replace(sch, new, &q->qdisc);
1167 return 0;
1168}
1169
1170static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1171{
1172 struct netem_sched_data *q = qdisc_priv(sch);
1173 return q->qdisc;
1174}
1175
1176static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1177{
1178 return 1;
1179}
1180
1181static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1182{
1183 if (!walker->stop) {
1184 if (walker->count >= walker->skip)
1185 if (walker->fn(sch, 1, walker) < 0) {
1186 walker->stop = 1;
1187 return;
1188 }
1189 walker->count++;
1190 }
1191}
1192
1193static const struct Qdisc_class_ops netem_class_ops = {
1194 .graft = netem_graft,
1195 .leaf = netem_leaf,
1196 .find = netem_find,
1197 .walk = netem_walk,
1198 .dump = netem_dump_class,
1199};
1200
1201static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1202 .id = "netem",
1203 .cl_ops = &netem_class_ops,
1204 .priv_size = sizeof(struct netem_sched_data),
1205 .enqueue = netem_enqueue,
1206 .dequeue = netem_dequeue,
1207 .peek = qdisc_peek_dequeued,
1208 .init = netem_init,
1209 .reset = netem_reset,
1210 .destroy = netem_destroy,
1211 .change = netem_change,
1212 .dump = netem_dump,
1213 .owner = THIS_MODULE,
1214};
1215
1216
1217static int __init netem_module_init(void)
1218{
1219 pr_info("netem: version " VERSION "\n");
1220 return register_qdisc(&netem_qdisc_ops);
1221}
1222static void __exit netem_module_exit(void)
1223{
1224 unregister_qdisc(&netem_qdisc_ops);
1225}
1226module_init(netem_module_init)
1227module_exit(netem_module_exit)
1228MODULE_LICENSE("GPL");
1/*
2 * net/sched/sch_netem.c Network emulator
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License.
8 *
9 * Many of the algorithms and ideas for this came from
10 * NIST Net which is not copyrighted.
11 *
12 * Authors: Stephen Hemminger <shemminger@osdl.org>
13 * Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
14 */
15
16#include <linux/mm.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/types.h>
20#include <linux/kernel.h>
21#include <linux/errno.h>
22#include <linux/skbuff.h>
23#include <linux/vmalloc.h>
24#include <linux/rtnetlink.h>
25
26#include <net/netlink.h>
27#include <net/pkt_sched.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
68struct netem_sched_data {
69 struct Qdisc *qdisc;
70 struct qdisc_watchdog watchdog;
71
72 psched_tdiff_t latency;
73 psched_tdiff_t jitter;
74
75 u32 loss;
76 u32 limit;
77 u32 counter;
78 u32 gap;
79 u32 duplicate;
80 u32 reorder;
81 u32 corrupt;
82
83 struct crndstate {
84 u32 last;
85 u32 rho;
86 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
87
88 struct disttable {
89 u32 size;
90 s16 table[0];
91 } *delay_dist;
92
93 enum {
94 CLG_RANDOM,
95 CLG_4_STATES,
96 CLG_GILB_ELL,
97 } loss_model;
98
99 /* Correlated Loss Generation models */
100 struct clgstate {
101 /* state of the Markov chain */
102 u8 state;
103
104 /* 4-states and Gilbert-Elliot models */
105 u32 a1; /* p13 for 4-states or p for GE */
106 u32 a2; /* p31 for 4-states or r for GE */
107 u32 a3; /* p32 for 4-states or h for GE */
108 u32 a4; /* p14 for 4-states or 1-k for GE */
109 u32 a5; /* p23 used only in 4-states */
110 } clg;
111
112};
113
114/* Time stamp put into socket buffer control block */
115struct netem_skb_cb {
116 psched_time_t time_to_send;
117};
118
119static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
120{
121 BUILD_BUG_ON(sizeof(skb->cb) <
122 sizeof(struct qdisc_skb_cb) + sizeof(struct netem_skb_cb));
123 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
124}
125
126/* init_crandom - initialize correlated random number generator
127 * Use entropy source for initial seed.
128 */
129static void init_crandom(struct crndstate *state, unsigned long rho)
130{
131 state->rho = rho;
132 state->last = net_random();
133}
134
135/* get_crandom - correlated random number generator
136 * Next number depends on last value.
137 * rho is scaled to avoid floating point.
138 */
139static u32 get_crandom(struct crndstate *state)
140{
141 u64 value, rho;
142 unsigned long answer;
143
144 if (state->rho == 0) /* no correlation */
145 return net_random();
146
147 value = net_random();
148 rho = (u64)state->rho + 1;
149 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
150 state->last = answer;
151 return answer;
152}
153
154/* loss_4state - 4-state model loss generator
155 * Generates losses according to the 4-state Markov chain adopted in
156 * the GI (General and Intuitive) loss model.
157 */
158static bool loss_4state(struct netem_sched_data *q)
159{
160 struct clgstate *clg = &q->clg;
161 u32 rnd = net_random();
162
163 /*
164 * Makes a comparison between rnd and the transition
165 * probabilities outgoing from the current state, then decides the
166 * next state and if the next packet has to be transmitted or lost.
167 * The four states correspond to:
168 * 1 => successfully transmitted packets within a gap period
169 * 4 => isolated losses within a gap period
170 * 3 => lost packets within a burst period
171 * 2 => successfully transmitted packets within a burst period
172 */
173 switch (clg->state) {
174 case 1:
175 if (rnd < clg->a4) {
176 clg->state = 4;
177 return true;
178 } else if (clg->a4 < rnd && rnd < clg->a1) {
179 clg->state = 3;
180 return true;
181 } else if (clg->a1 < rnd)
182 clg->state = 1;
183
184 break;
185 case 2:
186 if (rnd < clg->a5) {
187 clg->state = 3;
188 return true;
189 } else
190 clg->state = 2;
191
192 break;
193 case 3:
194 if (rnd < clg->a3)
195 clg->state = 2;
196 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
197 clg->state = 1;
198 return true;
199 } else if (clg->a2 + clg->a3 < rnd) {
200 clg->state = 3;
201 return true;
202 }
203 break;
204 case 4:
205 clg->state = 1;
206 break;
207 }
208
209 return false;
210}
211
212/* loss_gilb_ell - Gilbert-Elliot model loss generator
213 * Generates losses according to the Gilbert-Elliot loss model or
214 * its special cases (Gilbert or Simple Gilbert)
215 *
216 * Makes a comparison between random number and the transition
217 * probabilities outgoing from the current state, then decides the
218 * next state. A second random number is extracted and the comparison
219 * with the loss probability of the current state decides if the next
220 * packet will be transmitted or lost.
221 */
222static bool loss_gilb_ell(struct netem_sched_data *q)
223{
224 struct clgstate *clg = &q->clg;
225
226 switch (clg->state) {
227 case 1:
228 if (net_random() < clg->a1)
229 clg->state = 2;
230 if (net_random() < clg->a4)
231 return true;
232 case 2:
233 if (net_random() < clg->a2)
234 clg->state = 1;
235 if (clg->a3 > net_random())
236 return true;
237 }
238
239 return false;
240}
241
242static bool loss_event(struct netem_sched_data *q)
243{
244 switch (q->loss_model) {
245 case CLG_RANDOM:
246 /* Random packet drop 0 => none, ~0 => all */
247 return q->loss && q->loss >= get_crandom(&q->loss_cor);
248
249 case CLG_4_STATES:
250 /* 4state loss model algorithm (used also for GI model)
251 * Extracts a value from the markov 4 state loss generator,
252 * if it is 1 drops a packet and if needed writes the event in
253 * the kernel logs
254 */
255 return loss_4state(q);
256
257 case CLG_GILB_ELL:
258 /* Gilbert-Elliot loss model algorithm
259 * Extracts a value from the Gilbert-Elliot loss generator,
260 * if it is 1 drops a packet and if needed writes the event in
261 * the kernel logs
262 */
263 return loss_gilb_ell(q);
264 }
265
266 return false; /* not reached */
267}
268
269
270/* tabledist - return a pseudo-randomly distributed value with mean mu and
271 * std deviation sigma. Uses table lookup to approximate the desired
272 * distribution, and a uniformly-distributed pseudo-random source.
273 */
274static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
275 struct crndstate *state,
276 const struct disttable *dist)
277{
278 psched_tdiff_t x;
279 long t;
280 u32 rnd;
281
282 if (sigma == 0)
283 return mu;
284
285 rnd = get_crandom(state);
286
287 /* default uniform distribution */
288 if (dist == NULL)
289 return (rnd % (2*sigma)) - sigma + mu;
290
291 t = dist->table[rnd % dist->size];
292 x = (sigma % NETEM_DIST_SCALE) * t;
293 if (x >= 0)
294 x += NETEM_DIST_SCALE/2;
295 else
296 x -= NETEM_DIST_SCALE/2;
297
298 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
299}
300
301/*
302 * Insert one skb into qdisc.
303 * Note: parent depends on return value to account for queue length.
304 * NET_XMIT_DROP: queue length didn't change.
305 * NET_XMIT_SUCCESS: one skb was queued.
306 */
307static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
308{
309 struct netem_sched_data *q = qdisc_priv(sch);
310 /* We don't fill cb now as skb_unshare() may invalidate it */
311 struct netem_skb_cb *cb;
312 struct sk_buff *skb2;
313 int ret;
314 int count = 1;
315
316 /* Random duplication */
317 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
318 ++count;
319
320 /* Drop packet? */
321 if (loss_event(q))
322 --count;
323
324 if (count == 0) {
325 sch->qstats.drops++;
326 kfree_skb(skb);
327 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
328 }
329
330 skb_orphan(skb);
331
332 /*
333 * If we need to duplicate packet, then re-insert at top of the
334 * qdisc tree, since parent queuer expects that only one
335 * skb will be queued.
336 */
337 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
338 struct Qdisc *rootq = qdisc_root(sch);
339 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
340 q->duplicate = 0;
341
342 qdisc_enqueue_root(skb2, rootq);
343 q->duplicate = dupsave;
344 }
345
346 /*
347 * Randomized packet corruption.
348 * Make copy if needed since we are modifying
349 * If packet is going to be hardware checksummed, then
350 * do it now in software before we mangle it.
351 */
352 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
353 if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
354 (skb->ip_summed == CHECKSUM_PARTIAL &&
355 skb_checksum_help(skb))) {
356 sch->qstats.drops++;
357 return NET_XMIT_DROP;
358 }
359
360 skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
361 }
362
363 cb = netem_skb_cb(skb);
364 if (q->gap == 0 || /* not doing reordering */
365 q->counter < q->gap || /* inside last reordering gap */
366 q->reorder < get_crandom(&q->reorder_cor)) {
367 psched_time_t now;
368 psched_tdiff_t delay;
369
370 delay = tabledist(q->latency, q->jitter,
371 &q->delay_cor, q->delay_dist);
372
373 now = psched_get_time();
374 cb->time_to_send = now + delay;
375 ++q->counter;
376 ret = qdisc_enqueue(skb, q->qdisc);
377 } else {
378 /*
379 * Do re-ordering by putting one out of N packets at the front
380 * of the queue.
381 */
382 cb->time_to_send = psched_get_time();
383 q->counter = 0;
384
385 __skb_queue_head(&q->qdisc->q, skb);
386 q->qdisc->qstats.backlog += qdisc_pkt_len(skb);
387 q->qdisc->qstats.requeues++;
388 ret = NET_XMIT_SUCCESS;
389 }
390
391 if (ret != NET_XMIT_SUCCESS) {
392 if (net_xmit_drop_count(ret)) {
393 sch->qstats.drops++;
394 return ret;
395 }
396 }
397
398 sch->q.qlen++;
399 return NET_XMIT_SUCCESS;
400}
401
402static unsigned int netem_drop(struct Qdisc *sch)
403{
404 struct netem_sched_data *q = qdisc_priv(sch);
405 unsigned int len = 0;
406
407 if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
408 sch->q.qlen--;
409 sch->qstats.drops++;
410 }
411 return len;
412}
413
414static struct sk_buff *netem_dequeue(struct Qdisc *sch)
415{
416 struct netem_sched_data *q = qdisc_priv(sch);
417 struct sk_buff *skb;
418
419 if (qdisc_is_throttled(sch))
420 return NULL;
421
422 skb = q->qdisc->ops->peek(q->qdisc);
423 if (skb) {
424 const struct netem_skb_cb *cb = netem_skb_cb(skb);
425 psched_time_t now = psched_get_time();
426
427 /* if more time remaining? */
428 if (cb->time_to_send <= now) {
429 skb = qdisc_dequeue_peeked(q->qdisc);
430 if (unlikely(!skb))
431 return NULL;
432
433#ifdef CONFIG_NET_CLS_ACT
434 /*
435 * If it's at ingress let's pretend the delay is
436 * from the network (tstamp will be updated).
437 */
438 if (G_TC_FROM(skb->tc_verd) & AT_INGRESS)
439 skb->tstamp.tv64 = 0;
440#endif
441
442 sch->q.qlen--;
443 qdisc_unthrottled(sch);
444 qdisc_bstats_update(sch, skb);
445 return skb;
446 }
447
448 qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
449 }
450
451 return NULL;
452}
453
454static void netem_reset(struct Qdisc *sch)
455{
456 struct netem_sched_data *q = qdisc_priv(sch);
457
458 qdisc_reset(q->qdisc);
459 sch->q.qlen = 0;
460 qdisc_watchdog_cancel(&q->watchdog);
461}
462
463static void dist_free(struct disttable *d)
464{
465 if (d) {
466 if (is_vmalloc_addr(d))
467 vfree(d);
468 else
469 kfree(d);
470 }
471}
472
473/*
474 * Distribution data is a variable size payload containing
475 * signed 16 bit values.
476 */
477static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
478{
479 struct netem_sched_data *q = qdisc_priv(sch);
480 size_t n = nla_len(attr)/sizeof(__s16);
481 const __s16 *data = nla_data(attr);
482 spinlock_t *root_lock;
483 struct disttable *d;
484 int i;
485 size_t s;
486
487 if (n > NETEM_DIST_MAX)
488 return -EINVAL;
489
490 s = sizeof(struct disttable) + n * sizeof(s16);
491 d = kmalloc(s, GFP_KERNEL);
492 if (!d)
493 d = vmalloc(s);
494 if (!d)
495 return -ENOMEM;
496
497 d->size = n;
498 for (i = 0; i < n; i++)
499 d->table[i] = data[i];
500
501 root_lock = qdisc_root_sleeping_lock(sch);
502
503 spin_lock_bh(root_lock);
504 dist_free(q->delay_dist);
505 q->delay_dist = d;
506 spin_unlock_bh(root_lock);
507 return 0;
508}
509
510static void get_correlation(struct Qdisc *sch, const struct nlattr *attr)
511{
512 struct netem_sched_data *q = qdisc_priv(sch);
513 const struct tc_netem_corr *c = nla_data(attr);
514
515 init_crandom(&q->delay_cor, c->delay_corr);
516 init_crandom(&q->loss_cor, c->loss_corr);
517 init_crandom(&q->dup_cor, c->dup_corr);
518}
519
520static void get_reorder(struct Qdisc *sch, const struct nlattr *attr)
521{
522 struct netem_sched_data *q = qdisc_priv(sch);
523 const struct tc_netem_reorder *r = nla_data(attr);
524
525 q->reorder = r->probability;
526 init_crandom(&q->reorder_cor, r->correlation);
527}
528
529static void get_corrupt(struct Qdisc *sch, const struct nlattr *attr)
530{
531 struct netem_sched_data *q = qdisc_priv(sch);
532 const struct tc_netem_corrupt *r = nla_data(attr);
533
534 q->corrupt = r->probability;
535 init_crandom(&q->corrupt_cor, r->correlation);
536}
537
538static int get_loss_clg(struct Qdisc *sch, const struct nlattr *attr)
539{
540 struct netem_sched_data *q = qdisc_priv(sch);
541 const struct nlattr *la;
542 int rem;
543
544 nla_for_each_nested(la, attr, rem) {
545 u16 type = nla_type(la);
546
547 switch(type) {
548 case NETEM_LOSS_GI: {
549 const struct tc_netem_gimodel *gi = nla_data(la);
550
551 if (nla_len(la) != sizeof(struct tc_netem_gimodel)) {
552 pr_info("netem: incorrect gi model size\n");
553 return -EINVAL;
554 }
555
556 q->loss_model = CLG_4_STATES;
557
558 q->clg.state = 1;
559 q->clg.a1 = gi->p13;
560 q->clg.a2 = gi->p31;
561 q->clg.a3 = gi->p32;
562 q->clg.a4 = gi->p14;
563 q->clg.a5 = gi->p23;
564 break;
565 }
566
567 case NETEM_LOSS_GE: {
568 const struct tc_netem_gemodel *ge = nla_data(la);
569
570 if (nla_len(la) != sizeof(struct tc_netem_gemodel)) {
571 pr_info("netem: incorrect gi model size\n");
572 return -EINVAL;
573 }
574
575 q->loss_model = CLG_GILB_ELL;
576 q->clg.state = 1;
577 q->clg.a1 = ge->p;
578 q->clg.a2 = ge->r;
579 q->clg.a3 = ge->h;
580 q->clg.a4 = ge->k1;
581 break;
582 }
583
584 default:
585 pr_info("netem: unknown loss type %u\n", type);
586 return -EINVAL;
587 }
588 }
589
590 return 0;
591}
592
593static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
594 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
595 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
596 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
597 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
598};
599
600static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
601 const struct nla_policy *policy, int len)
602{
603 int nested_len = nla_len(nla) - NLA_ALIGN(len);
604
605 if (nested_len < 0) {
606 pr_info("netem: invalid attributes len %d\n", nested_len);
607 return -EINVAL;
608 }
609
610 if (nested_len >= nla_attr_size(0))
611 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
612 nested_len, policy);
613
614 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
615 return 0;
616}
617
618/* Parse netlink message to set options */
619static int netem_change(struct Qdisc *sch, struct nlattr *opt)
620{
621 struct netem_sched_data *q = qdisc_priv(sch);
622 struct nlattr *tb[TCA_NETEM_MAX + 1];
623 struct tc_netem_qopt *qopt;
624 int ret;
625
626 if (opt == NULL)
627 return -EINVAL;
628
629 qopt = nla_data(opt);
630 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
631 if (ret < 0)
632 return ret;
633
634 ret = fifo_set_limit(q->qdisc, qopt->limit);
635 if (ret) {
636 pr_info("netem: can't set fifo limit\n");
637 return ret;
638 }
639
640 q->latency = qopt->latency;
641 q->jitter = qopt->jitter;
642 q->limit = qopt->limit;
643 q->gap = qopt->gap;
644 q->counter = 0;
645 q->loss = qopt->loss;
646 q->duplicate = qopt->duplicate;
647
648 /* for compatibility with earlier versions.
649 * if gap is set, need to assume 100% probability
650 */
651 if (q->gap)
652 q->reorder = ~0;
653
654 if (tb[TCA_NETEM_CORR])
655 get_correlation(sch, tb[TCA_NETEM_CORR]);
656
657 if (tb[TCA_NETEM_DELAY_DIST]) {
658 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
659 if (ret)
660 return ret;
661 }
662
663 if (tb[TCA_NETEM_REORDER])
664 get_reorder(sch, tb[TCA_NETEM_REORDER]);
665
666 if (tb[TCA_NETEM_CORRUPT])
667 get_corrupt(sch, tb[TCA_NETEM_CORRUPT]);
668
669 q->loss_model = CLG_RANDOM;
670 if (tb[TCA_NETEM_LOSS])
671 ret = get_loss_clg(sch, tb[TCA_NETEM_LOSS]);
672
673 return ret;
674}
675
676/*
677 * Special case version of FIFO queue for use by netem.
678 * It queues in order based on timestamps in skb's
679 */
680struct fifo_sched_data {
681 u32 limit;
682 psched_time_t oldest;
683};
684
685static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
686{
687 struct fifo_sched_data *q = qdisc_priv(sch);
688 struct sk_buff_head *list = &sch->q;
689 psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
690 struct sk_buff *skb;
691
692 if (likely(skb_queue_len(list) < q->limit)) {
693 /* Optimize for add at tail */
694 if (likely(skb_queue_empty(list) || tnext >= q->oldest)) {
695 q->oldest = tnext;
696 return qdisc_enqueue_tail(nskb, sch);
697 }
698
699 skb_queue_reverse_walk(list, skb) {
700 const struct netem_skb_cb *cb = netem_skb_cb(skb);
701
702 if (tnext >= cb->time_to_send)
703 break;
704 }
705
706 __skb_queue_after(list, skb, nskb);
707
708 sch->qstats.backlog += qdisc_pkt_len(nskb);
709
710 return NET_XMIT_SUCCESS;
711 }
712
713 return qdisc_reshape_fail(nskb, sch);
714}
715
716static int tfifo_init(struct Qdisc *sch, struct nlattr *opt)
717{
718 struct fifo_sched_data *q = qdisc_priv(sch);
719
720 if (opt) {
721 struct tc_fifo_qopt *ctl = nla_data(opt);
722 if (nla_len(opt) < sizeof(*ctl))
723 return -EINVAL;
724
725 q->limit = ctl->limit;
726 } else
727 q->limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
728
729 q->oldest = PSCHED_PASTPERFECT;
730 return 0;
731}
732
733static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
734{
735 struct fifo_sched_data *q = qdisc_priv(sch);
736 struct tc_fifo_qopt opt = { .limit = q->limit };
737
738 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
739 return skb->len;
740
741nla_put_failure:
742 return -1;
743}
744
745static struct Qdisc_ops tfifo_qdisc_ops __read_mostly = {
746 .id = "tfifo",
747 .priv_size = sizeof(struct fifo_sched_data),
748 .enqueue = tfifo_enqueue,
749 .dequeue = qdisc_dequeue_head,
750 .peek = qdisc_peek_head,
751 .drop = qdisc_queue_drop,
752 .init = tfifo_init,
753 .reset = qdisc_reset_queue,
754 .change = tfifo_init,
755 .dump = tfifo_dump,
756};
757
758static int netem_init(struct Qdisc *sch, struct nlattr *opt)
759{
760 struct netem_sched_data *q = qdisc_priv(sch);
761 int ret;
762
763 if (!opt)
764 return -EINVAL;
765
766 qdisc_watchdog_init(&q->watchdog, sch);
767
768 q->loss_model = CLG_RANDOM;
769 q->qdisc = qdisc_create_dflt(sch->dev_queue, &tfifo_qdisc_ops,
770 TC_H_MAKE(sch->handle, 1));
771 if (!q->qdisc) {
772 pr_notice("netem: qdisc create tfifo qdisc failed\n");
773 return -ENOMEM;
774 }
775
776 ret = netem_change(sch, opt);
777 if (ret) {
778 pr_info("netem: change failed\n");
779 qdisc_destroy(q->qdisc);
780 }
781 return ret;
782}
783
784static void netem_destroy(struct Qdisc *sch)
785{
786 struct netem_sched_data *q = qdisc_priv(sch);
787
788 qdisc_watchdog_cancel(&q->watchdog);
789 qdisc_destroy(q->qdisc);
790 dist_free(q->delay_dist);
791}
792
793static int dump_loss_model(const struct netem_sched_data *q,
794 struct sk_buff *skb)
795{
796 struct nlattr *nest;
797
798 nest = nla_nest_start(skb, TCA_NETEM_LOSS);
799 if (nest == NULL)
800 goto nla_put_failure;
801
802 switch (q->loss_model) {
803 case CLG_RANDOM:
804 /* legacy loss model */
805 nla_nest_cancel(skb, nest);
806 return 0; /* no data */
807
808 case CLG_4_STATES: {
809 struct tc_netem_gimodel gi = {
810 .p13 = q->clg.a1,
811 .p31 = q->clg.a2,
812 .p32 = q->clg.a3,
813 .p14 = q->clg.a4,
814 .p23 = q->clg.a5,
815 };
816
817 NLA_PUT(skb, NETEM_LOSS_GI, sizeof(gi), &gi);
818 break;
819 }
820 case CLG_GILB_ELL: {
821 struct tc_netem_gemodel ge = {
822 .p = q->clg.a1,
823 .r = q->clg.a2,
824 .h = q->clg.a3,
825 .k1 = q->clg.a4,
826 };
827
828 NLA_PUT(skb, NETEM_LOSS_GE, sizeof(ge), &ge);
829 break;
830 }
831 }
832
833 nla_nest_end(skb, nest);
834 return 0;
835
836nla_put_failure:
837 nla_nest_cancel(skb, nest);
838 return -1;
839}
840
841static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
842{
843 const struct netem_sched_data *q = qdisc_priv(sch);
844 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
845 struct tc_netem_qopt qopt;
846 struct tc_netem_corr cor;
847 struct tc_netem_reorder reorder;
848 struct tc_netem_corrupt corrupt;
849
850 qopt.latency = q->latency;
851 qopt.jitter = q->jitter;
852 qopt.limit = q->limit;
853 qopt.loss = q->loss;
854 qopt.gap = q->gap;
855 qopt.duplicate = q->duplicate;
856 NLA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
857
858 cor.delay_corr = q->delay_cor.rho;
859 cor.loss_corr = q->loss_cor.rho;
860 cor.dup_corr = q->dup_cor.rho;
861 NLA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor);
862
863 reorder.probability = q->reorder;
864 reorder.correlation = q->reorder_cor.rho;
865 NLA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder);
866
867 corrupt.probability = q->corrupt;
868 corrupt.correlation = q->corrupt_cor.rho;
869 NLA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
870
871 if (dump_loss_model(q, skb) != 0)
872 goto nla_put_failure;
873
874 return nla_nest_end(skb, nla);
875
876nla_put_failure:
877 nlmsg_trim(skb, nla);
878 return -1;
879}
880
881static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
882 struct sk_buff *skb, struct tcmsg *tcm)
883{
884 struct netem_sched_data *q = qdisc_priv(sch);
885
886 if (cl != 1) /* only one class */
887 return -ENOENT;
888
889 tcm->tcm_handle |= TC_H_MIN(1);
890 tcm->tcm_info = q->qdisc->handle;
891
892 return 0;
893}
894
895static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
896 struct Qdisc **old)
897{
898 struct netem_sched_data *q = qdisc_priv(sch);
899
900 if (new == NULL)
901 new = &noop_qdisc;
902
903 sch_tree_lock(sch);
904 *old = q->qdisc;
905 q->qdisc = new;
906 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
907 qdisc_reset(*old);
908 sch_tree_unlock(sch);
909
910 return 0;
911}
912
913static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
914{
915 struct netem_sched_data *q = qdisc_priv(sch);
916 return q->qdisc;
917}
918
919static unsigned long netem_get(struct Qdisc *sch, u32 classid)
920{
921 return 1;
922}
923
924static void netem_put(struct Qdisc *sch, unsigned long arg)
925{
926}
927
928static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
929{
930 if (!walker->stop) {
931 if (walker->count >= walker->skip)
932 if (walker->fn(sch, 1, walker) < 0) {
933 walker->stop = 1;
934 return;
935 }
936 walker->count++;
937 }
938}
939
940static const struct Qdisc_class_ops netem_class_ops = {
941 .graft = netem_graft,
942 .leaf = netem_leaf,
943 .get = netem_get,
944 .put = netem_put,
945 .walk = netem_walk,
946 .dump = netem_dump_class,
947};
948
949static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
950 .id = "netem",
951 .cl_ops = &netem_class_ops,
952 .priv_size = sizeof(struct netem_sched_data),
953 .enqueue = netem_enqueue,
954 .dequeue = netem_dequeue,
955 .peek = qdisc_peek_dequeued,
956 .drop = netem_drop,
957 .init = netem_init,
958 .reset = netem_reset,
959 .destroy = netem_destroy,
960 .change = netem_change,
961 .dump = netem_dump,
962 .owner = THIS_MODULE,
963};
964
965
966static int __init netem_module_init(void)
967{
968 pr_info("netem: version " VERSION "\n");
969 return register_qdisc(&netem_qdisc_ops);
970}
971static void __exit netem_module_exit(void)
972{
973 unregister_qdisc(&netem_qdisc_ops);
974}
975module_init(netem_module_init)
976module_exit(netem_module_exit)
977MODULE_LICENSE("GPL");