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
71 struct 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 psched_tdiff_t latency;
81 psched_tdiff_t 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 };
139
140 /* Time stamp put into socket buffer control block
141 * Only valid when skbs are in our internal t(ime)fifo queue.
142 *
143 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
144 * and skb->next & skb->prev are scratch space for a qdisc,
145 * we save skb->tstamp value in skb->cb[] before destroying it.
146 */
147 struct netem_skb_cb {
148 psched_time_t time_to_send;
149 ktime_t tstamp_save;
150 };
151
152
netem_rb_to_skb(struct rb_node * rb)153 static struct sk_buff *netem_rb_to_skb(struct rb_node *rb)
154 {
155 return container_of(rb, struct sk_buff, rbnode);
156 }
157
netem_skb_cb(struct sk_buff * skb)158 static 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 */
init_crandom(struct crndstate * state,unsigned long rho)168 static 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 */
get_crandom(struct crndstate * state)178 static 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 */
loss_4state(struct netem_sched_data * q)197 static 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 */
loss_gilb_ell(struct netem_sched_data * q)262 static 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
loss_event(struct netem_sched_data * q)283 static 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 */
tabledist(psched_tdiff_t mu,psched_tdiff_t sigma,struct crndstate * state,const struct disttable * dist)315 static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
316 struct crndstate *state,
317 const struct disttable *dist)
318 {
319 psched_tdiff_t 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)) - sigma + mu;
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
packet_len_2_sched_time(unsigned int len,struct netem_sched_data * q)342 static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sched_data *q)
343 {
344 u64 ticks;
345
346 len += q->packet_overhead;
347
348 if (q->cell_size) {
349 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
350
351 if (len > cells * q->cell_size) /* extra cell needed for remainder */
352 cells++;
353 len = cells * (q->cell_size + q->cell_overhead);
354 }
355
356 ticks = (u64)len * NSEC_PER_SEC;
357
358 do_div(ticks, q->rate);
359 return PSCHED_NS2TICKS(ticks);
360 }
361
tfifo_reset(struct Qdisc * sch)362 static void tfifo_reset(struct Qdisc *sch)
363 {
364 struct netem_sched_data *q = qdisc_priv(sch);
365 struct rb_node *p;
366
367 while ((p = rb_first(&q->t_root))) {
368 struct sk_buff *skb = netem_rb_to_skb(p);
369
370 rb_erase(p, &q->t_root);
371 rtnl_kfree_skbs(skb, skb);
372 }
373 }
374
tfifo_enqueue(struct sk_buff * nskb,struct Qdisc * sch)375 static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
376 {
377 struct netem_sched_data *q = qdisc_priv(sch);
378 psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
379 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
380
381 while (*p) {
382 struct sk_buff *skb;
383
384 parent = *p;
385 skb = netem_rb_to_skb(parent);
386 if (tnext >= netem_skb_cb(skb)->time_to_send)
387 p = &parent->rb_right;
388 else
389 p = &parent->rb_left;
390 }
391 rb_link_node(&nskb->rbnode, parent, p);
392 rb_insert_color(&nskb->rbnode, &q->t_root);
393 sch->q.qlen++;
394 }
395
396 /* netem can't properly corrupt a megapacket (like we get from GSO), so instead
397 * when we statistically choose to corrupt one, we instead segment it, returning
398 * the first packet to be corrupted, and re-enqueue the remaining frames
399 */
netem_segment(struct sk_buff * skb,struct Qdisc * sch,struct sk_buff ** to_free)400 static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
401 struct sk_buff **to_free)
402 {
403 struct sk_buff *segs;
404 netdev_features_t features = netif_skb_features(skb);
405
406 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
407
408 if (IS_ERR_OR_NULL(segs)) {
409 qdisc_drop(skb, sch, to_free);
410 return NULL;
411 }
412 consume_skb(skb);
413 return segs;
414 }
415
netem_enqueue_skb_head(struct qdisc_skb_head * qh,struct sk_buff * skb)416 static void netem_enqueue_skb_head(struct qdisc_skb_head *qh, struct sk_buff *skb)
417 {
418 skb->next = qh->head;
419
420 if (!qh->head)
421 qh->tail = skb;
422 qh->head = skb;
423 qh->qlen++;
424 }
425
426 /*
427 * Insert one skb into qdisc.
428 * Note: parent depends on return value to account for queue length.
429 * NET_XMIT_DROP: queue length didn't change.
430 * NET_XMIT_SUCCESS: one skb was queued.
431 */
netem_enqueue(struct sk_buff * skb,struct Qdisc * sch,struct sk_buff ** to_free)432 static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
433 struct sk_buff **to_free)
434 {
435 struct netem_sched_data *q = qdisc_priv(sch);
436 /* We don't fill cb now as skb_unshare() may invalidate it */
437 struct netem_skb_cb *cb;
438 struct sk_buff *skb2;
439 struct sk_buff *segs = NULL;
440 unsigned int len = 0, last_len, prev_len = qdisc_pkt_len(skb);
441 int nb = 0;
442 int count = 1;
443 int rc = NET_XMIT_SUCCESS;
444
445 /* Random duplication */
446 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
447 ++count;
448
449 /* Drop packet? */
450 if (loss_event(q)) {
451 if (q->ecn && INET_ECN_set_ce(skb))
452 qdisc_qstats_drop(sch); /* mark packet */
453 else
454 --count;
455 }
456 if (count == 0) {
457 qdisc_qstats_drop(sch);
458 __qdisc_drop(skb, to_free);
459 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
460 }
461
462 /* If a delay is expected, orphan the skb. (orphaning usually takes
463 * place at TX completion time, so _before_ the link transit delay)
464 */
465 if (q->latency || q->jitter || q->rate)
466 skb_orphan_partial(skb);
467
468 /*
469 * If we need to duplicate packet, then re-insert at top of the
470 * qdisc tree, since parent queuer expects that only one
471 * skb will be queued.
472 */
473 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
474 struct Qdisc *rootq = qdisc_root(sch);
475 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
476
477 q->duplicate = 0;
478 rootq->enqueue(skb2, rootq, to_free);
479 q->duplicate = dupsave;
480 }
481
482 /*
483 * Randomized packet corruption.
484 * Make copy if needed since we are modifying
485 * If packet is going to be hardware checksummed, then
486 * do it now in software before we mangle it.
487 */
488 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
489 if (skb_is_gso(skb)) {
490 segs = netem_segment(skb, sch, to_free);
491 if (!segs)
492 return NET_XMIT_DROP;
493 } else {
494 segs = skb;
495 }
496
497 skb = segs;
498 segs = segs->next;
499
500 skb = skb_unshare(skb, GFP_ATOMIC);
501 if (unlikely(!skb)) {
502 qdisc_qstats_drop(sch);
503 goto finish_segs;
504 }
505 if (skb->ip_summed == CHECKSUM_PARTIAL &&
506 skb_checksum_help(skb)) {
507 qdisc_drop(skb, sch, to_free);
508 goto finish_segs;
509 }
510
511 skb->data[prandom_u32() % skb_headlen(skb)] ^=
512 1<<(prandom_u32() % 8);
513 }
514
515 if (unlikely(sch->q.qlen >= sch->limit))
516 return qdisc_drop_all(skb, sch, to_free);
517
518 qdisc_qstats_backlog_inc(sch, skb);
519
520 cb = netem_skb_cb(skb);
521 if (q->gap == 0 || /* not doing reordering */
522 q->counter < q->gap - 1 || /* inside last reordering gap */
523 q->reorder < get_crandom(&q->reorder_cor)) {
524 psched_time_t now;
525 psched_tdiff_t delay;
526
527 delay = tabledist(q->latency, q->jitter,
528 &q->delay_cor, q->delay_dist);
529
530 now = psched_get_time();
531
532 if (q->rate) {
533 struct netem_skb_cb *last = NULL;
534
535 if (sch->q.tail)
536 last = netem_skb_cb(sch->q.tail);
537 if (q->t_root.rb_node) {
538 struct sk_buff *t_skb;
539 struct netem_skb_cb *t_last;
540
541 t_skb = netem_rb_to_skb(rb_last(&q->t_root));
542 t_last = netem_skb_cb(t_skb);
543 if (!last ||
544 t_last->time_to_send > last->time_to_send) {
545 last = t_last;
546 }
547 }
548
549 if (last) {
550 /*
551 * Last packet in queue is reference point (now),
552 * calculate this time bonus and subtract
553 * from delay.
554 */
555 delay -= last->time_to_send - now;
556 delay = max_t(psched_tdiff_t, 0, delay);
557 now = last->time_to_send;
558 }
559
560 delay += packet_len_2_sched_time(qdisc_pkt_len(skb), q);
561 }
562
563 cb->time_to_send = now + delay;
564 cb->tstamp_save = skb->tstamp;
565 ++q->counter;
566 tfifo_enqueue(skb, sch);
567 } else {
568 /*
569 * Do re-ordering by putting one out of N packets at the front
570 * of the queue.
571 */
572 cb->time_to_send = psched_get_time();
573 q->counter = 0;
574
575 netem_enqueue_skb_head(&sch->q, skb);
576 sch->qstats.requeues++;
577 }
578
579 finish_segs:
580 if (segs) {
581 while (segs) {
582 skb2 = segs->next;
583 segs->next = NULL;
584 qdisc_skb_cb(segs)->pkt_len = segs->len;
585 last_len = segs->len;
586 rc = qdisc_enqueue(segs, sch, to_free);
587 if (rc != NET_XMIT_SUCCESS) {
588 if (net_xmit_drop_count(rc))
589 qdisc_qstats_drop(sch);
590 } else {
591 nb++;
592 len += last_len;
593 }
594 segs = skb2;
595 }
596 sch->q.qlen += nb;
597 if (nb > 1)
598 qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
599 }
600 return NET_XMIT_SUCCESS;
601 }
602
netem_dequeue(struct Qdisc * sch)603 static struct sk_buff *netem_dequeue(struct Qdisc *sch)
604 {
605 struct netem_sched_data *q = qdisc_priv(sch);
606 struct sk_buff *skb;
607 struct rb_node *p;
608
609 tfifo_dequeue:
610 skb = __qdisc_dequeue_head(&sch->q);
611 if (skb) {
612 qdisc_qstats_backlog_dec(sch, skb);
613 deliver:
614 qdisc_bstats_update(sch, skb);
615 return skb;
616 }
617 p = rb_first(&q->t_root);
618 if (p) {
619 psched_time_t time_to_send;
620
621 skb = netem_rb_to_skb(p);
622
623 /* if more time remaining? */
624 time_to_send = netem_skb_cb(skb)->time_to_send;
625 if (time_to_send <= psched_get_time()) {
626 rb_erase(p, &q->t_root);
627
628 sch->q.qlen--;
629 qdisc_qstats_backlog_dec(sch, skb);
630 skb->next = NULL;
631 skb->prev = NULL;
632 skb->tstamp = netem_skb_cb(skb)->tstamp_save;
633
634 #ifdef CONFIG_NET_CLS_ACT
635 /*
636 * If it's at ingress let's pretend the delay is
637 * from the network (tstamp will be updated).
638 */
639 if (G_TC_FROM(skb->tc_verd) & AT_INGRESS)
640 skb->tstamp.tv64 = 0;
641 #endif
642
643 if (q->qdisc) {
644 unsigned int pkt_len = qdisc_pkt_len(skb);
645 struct sk_buff *to_free = NULL;
646 int err;
647
648 err = qdisc_enqueue(skb, q->qdisc, &to_free);
649 kfree_skb_list(to_free);
650 if (err != NET_XMIT_SUCCESS &&
651 net_xmit_drop_count(err)) {
652 qdisc_qstats_drop(sch);
653 qdisc_tree_reduce_backlog(sch, 1,
654 pkt_len);
655 }
656 goto tfifo_dequeue;
657 }
658 goto deliver;
659 }
660
661 if (q->qdisc) {
662 skb = q->qdisc->ops->dequeue(q->qdisc);
663 if (skb)
664 goto deliver;
665 }
666 qdisc_watchdog_schedule(&q->watchdog, time_to_send);
667 }
668
669 if (q->qdisc) {
670 skb = q->qdisc->ops->dequeue(q->qdisc);
671 if (skb)
672 goto deliver;
673 }
674 return NULL;
675 }
676
netem_reset(struct Qdisc * sch)677 static void netem_reset(struct Qdisc *sch)
678 {
679 struct netem_sched_data *q = qdisc_priv(sch);
680
681 qdisc_reset_queue(sch);
682 tfifo_reset(sch);
683 if (q->qdisc)
684 qdisc_reset(q->qdisc);
685 qdisc_watchdog_cancel(&q->watchdog);
686 }
687
dist_free(struct disttable * d)688 static void dist_free(struct disttable *d)
689 {
690 kvfree(d);
691 }
692
693 /*
694 * Distribution data is a variable size payload containing
695 * signed 16 bit values.
696 */
get_dist_table(struct Qdisc * sch,const struct nlattr * attr)697 static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
698 {
699 struct netem_sched_data *q = qdisc_priv(sch);
700 size_t n = nla_len(attr)/sizeof(__s16);
701 const __s16 *data = nla_data(attr);
702 spinlock_t *root_lock;
703 struct disttable *d;
704 int i;
705 size_t s;
706
707 if (n > NETEM_DIST_MAX)
708 return -EINVAL;
709
710 s = sizeof(struct disttable) + n * sizeof(s16);
711 d = kmalloc(s, GFP_KERNEL | __GFP_NOWARN);
712 if (!d)
713 d = vmalloc(s);
714 if (!d)
715 return -ENOMEM;
716
717 d->size = n;
718 for (i = 0; i < n; i++)
719 d->table[i] = data[i];
720
721 root_lock = qdisc_root_sleeping_lock(sch);
722
723 spin_lock_bh(root_lock);
724 swap(q->delay_dist, d);
725 spin_unlock_bh(root_lock);
726
727 dist_free(d);
728 return 0;
729 }
730
get_correlation(struct netem_sched_data * q,const struct nlattr * attr)731 static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
732 {
733 const struct tc_netem_corr *c = nla_data(attr);
734
735 init_crandom(&q->delay_cor, c->delay_corr);
736 init_crandom(&q->loss_cor, c->loss_corr);
737 init_crandom(&q->dup_cor, c->dup_corr);
738 }
739
get_reorder(struct netem_sched_data * q,const struct nlattr * attr)740 static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
741 {
742 const struct tc_netem_reorder *r = nla_data(attr);
743
744 q->reorder = r->probability;
745 init_crandom(&q->reorder_cor, r->correlation);
746 }
747
get_corrupt(struct netem_sched_data * q,const struct nlattr * attr)748 static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
749 {
750 const struct tc_netem_corrupt *r = nla_data(attr);
751
752 q->corrupt = r->probability;
753 init_crandom(&q->corrupt_cor, r->correlation);
754 }
755
get_rate(struct netem_sched_data * q,const struct nlattr * attr)756 static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
757 {
758 const struct tc_netem_rate *r = nla_data(attr);
759
760 q->rate = r->rate;
761 q->packet_overhead = r->packet_overhead;
762 q->cell_size = r->cell_size;
763 q->cell_overhead = r->cell_overhead;
764 if (q->cell_size)
765 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
766 else
767 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
768 }
769
get_loss_clg(struct netem_sched_data * q,const struct nlattr * attr)770 static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
771 {
772 const struct nlattr *la;
773 int rem;
774
775 nla_for_each_nested(la, attr, rem) {
776 u16 type = nla_type(la);
777
778 switch (type) {
779 case NETEM_LOSS_GI: {
780 const struct tc_netem_gimodel *gi = nla_data(la);
781
782 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
783 pr_info("netem: incorrect gi model size\n");
784 return -EINVAL;
785 }
786
787 q->loss_model = CLG_4_STATES;
788
789 q->clg.state = TX_IN_GAP_PERIOD;
790 q->clg.a1 = gi->p13;
791 q->clg.a2 = gi->p31;
792 q->clg.a3 = gi->p32;
793 q->clg.a4 = gi->p14;
794 q->clg.a5 = gi->p23;
795 break;
796 }
797
798 case NETEM_LOSS_GE: {
799 const struct tc_netem_gemodel *ge = nla_data(la);
800
801 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
802 pr_info("netem: incorrect ge model size\n");
803 return -EINVAL;
804 }
805
806 q->loss_model = CLG_GILB_ELL;
807 q->clg.state = GOOD_STATE;
808 q->clg.a1 = ge->p;
809 q->clg.a2 = ge->r;
810 q->clg.a3 = ge->h;
811 q->clg.a4 = ge->k1;
812 break;
813 }
814
815 default:
816 pr_info("netem: unknown loss type %u\n", type);
817 return -EINVAL;
818 }
819 }
820
821 return 0;
822 }
823
824 static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
825 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
826 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
827 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
828 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
829 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
830 [TCA_NETEM_ECN] = { .type = NLA_U32 },
831 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
832 };
833
parse_attr(struct nlattr * tb[],int maxtype,struct nlattr * nla,const struct nla_policy * policy,int len)834 static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
835 const struct nla_policy *policy, int len)
836 {
837 int nested_len = nla_len(nla) - NLA_ALIGN(len);
838
839 if (nested_len < 0) {
840 pr_info("netem: invalid attributes len %d\n", nested_len);
841 return -EINVAL;
842 }
843
844 if (nested_len >= nla_attr_size(0))
845 return nla_parse(tb, maxtype, nla_data(nla) + NLA_ALIGN(len),
846 nested_len, policy);
847
848 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
849 return 0;
850 }
851
852 /* Parse netlink message to set options */
netem_change(struct Qdisc * sch,struct nlattr * opt)853 static int netem_change(struct Qdisc *sch, struct nlattr *opt)
854 {
855 struct netem_sched_data *q = qdisc_priv(sch);
856 struct nlattr *tb[TCA_NETEM_MAX + 1];
857 struct tc_netem_qopt *qopt;
858 struct clgstate old_clg;
859 int old_loss_model = CLG_RANDOM;
860 int ret;
861
862 if (opt == NULL)
863 return -EINVAL;
864
865 qopt = nla_data(opt);
866 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
867 if (ret < 0)
868 return ret;
869
870 /* backup q->clg and q->loss_model */
871 old_clg = q->clg;
872 old_loss_model = q->loss_model;
873
874 if (tb[TCA_NETEM_LOSS]) {
875 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
876 if (ret) {
877 q->loss_model = old_loss_model;
878 return ret;
879 }
880 } else {
881 q->loss_model = CLG_RANDOM;
882 }
883
884 if (tb[TCA_NETEM_DELAY_DIST]) {
885 ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST]);
886 if (ret) {
887 /* recover clg and loss_model, in case of
888 * q->clg and q->loss_model were modified
889 * in get_loss_clg()
890 */
891 q->clg = old_clg;
892 q->loss_model = old_loss_model;
893 return ret;
894 }
895 }
896
897 sch->limit = qopt->limit;
898
899 q->latency = qopt->latency;
900 q->jitter = qopt->jitter;
901 q->limit = qopt->limit;
902 q->gap = qopt->gap;
903 q->counter = 0;
904 q->loss = qopt->loss;
905 q->duplicate = qopt->duplicate;
906
907 /* for compatibility with earlier versions.
908 * if gap is set, need to assume 100% probability
909 */
910 if (q->gap)
911 q->reorder = ~0;
912
913 if (tb[TCA_NETEM_CORR])
914 get_correlation(q, tb[TCA_NETEM_CORR]);
915
916 if (tb[TCA_NETEM_REORDER])
917 get_reorder(q, tb[TCA_NETEM_REORDER]);
918
919 if (tb[TCA_NETEM_CORRUPT])
920 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
921
922 if (tb[TCA_NETEM_RATE])
923 get_rate(q, tb[TCA_NETEM_RATE]);
924
925 if (tb[TCA_NETEM_RATE64])
926 q->rate = max_t(u64, q->rate,
927 nla_get_u64(tb[TCA_NETEM_RATE64]));
928
929 if (tb[TCA_NETEM_ECN])
930 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
931
932 return ret;
933 }
934
netem_init(struct Qdisc * sch,struct nlattr * opt)935 static int netem_init(struct Qdisc *sch, struct nlattr *opt)
936 {
937 struct netem_sched_data *q = qdisc_priv(sch);
938 int ret;
939
940 if (!opt)
941 return -EINVAL;
942
943 qdisc_watchdog_init(&q->watchdog, sch);
944
945 q->loss_model = CLG_RANDOM;
946 ret = netem_change(sch, opt);
947 if (ret)
948 pr_info("netem: change failed\n");
949 return ret;
950 }
951
netem_destroy(struct Qdisc * sch)952 static void netem_destroy(struct Qdisc *sch)
953 {
954 struct netem_sched_data *q = qdisc_priv(sch);
955
956 qdisc_watchdog_cancel(&q->watchdog);
957 if (q->qdisc)
958 qdisc_destroy(q->qdisc);
959 dist_free(q->delay_dist);
960 }
961
dump_loss_model(const struct netem_sched_data * q,struct sk_buff * skb)962 static int dump_loss_model(const struct netem_sched_data *q,
963 struct sk_buff *skb)
964 {
965 struct nlattr *nest;
966
967 nest = nla_nest_start(skb, TCA_NETEM_LOSS);
968 if (nest == NULL)
969 goto nla_put_failure;
970
971 switch (q->loss_model) {
972 case CLG_RANDOM:
973 /* legacy loss model */
974 nla_nest_cancel(skb, nest);
975 return 0; /* no data */
976
977 case CLG_4_STATES: {
978 struct tc_netem_gimodel gi = {
979 .p13 = q->clg.a1,
980 .p31 = q->clg.a2,
981 .p32 = q->clg.a3,
982 .p14 = q->clg.a4,
983 .p23 = q->clg.a5,
984 };
985
986 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
987 goto nla_put_failure;
988 break;
989 }
990 case CLG_GILB_ELL: {
991 struct tc_netem_gemodel ge = {
992 .p = q->clg.a1,
993 .r = q->clg.a2,
994 .h = q->clg.a3,
995 .k1 = q->clg.a4,
996 };
997
998 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
999 goto nla_put_failure;
1000 break;
1001 }
1002 }
1003
1004 nla_nest_end(skb, nest);
1005 return 0;
1006
1007 nla_put_failure:
1008 nla_nest_cancel(skb, nest);
1009 return -1;
1010 }
1011
netem_dump(struct Qdisc * sch,struct sk_buff * skb)1012 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1013 {
1014 const struct netem_sched_data *q = qdisc_priv(sch);
1015 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1016 struct tc_netem_qopt qopt;
1017 struct tc_netem_corr cor;
1018 struct tc_netem_reorder reorder;
1019 struct tc_netem_corrupt corrupt;
1020 struct tc_netem_rate rate;
1021
1022 qopt.latency = q->latency;
1023 qopt.jitter = q->jitter;
1024 qopt.limit = q->limit;
1025 qopt.loss = q->loss;
1026 qopt.gap = q->gap;
1027 qopt.duplicate = q->duplicate;
1028 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1029 goto nla_put_failure;
1030
1031 cor.delay_corr = q->delay_cor.rho;
1032 cor.loss_corr = q->loss_cor.rho;
1033 cor.dup_corr = q->dup_cor.rho;
1034 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1035 goto nla_put_failure;
1036
1037 reorder.probability = q->reorder;
1038 reorder.correlation = q->reorder_cor.rho;
1039 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1040 goto nla_put_failure;
1041
1042 corrupt.probability = q->corrupt;
1043 corrupt.correlation = q->corrupt_cor.rho;
1044 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1045 goto nla_put_failure;
1046
1047 if (q->rate >= (1ULL << 32)) {
1048 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1049 TCA_NETEM_PAD))
1050 goto nla_put_failure;
1051 rate.rate = ~0U;
1052 } else {
1053 rate.rate = q->rate;
1054 }
1055 rate.packet_overhead = q->packet_overhead;
1056 rate.cell_size = q->cell_size;
1057 rate.cell_overhead = q->cell_overhead;
1058 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1059 goto nla_put_failure;
1060
1061 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1062 goto nla_put_failure;
1063
1064 if (dump_loss_model(q, skb) != 0)
1065 goto nla_put_failure;
1066
1067 return nla_nest_end(skb, nla);
1068
1069 nla_put_failure:
1070 nlmsg_trim(skb, nla);
1071 return -1;
1072 }
1073
netem_dump_class(struct Qdisc * sch,unsigned long cl,struct sk_buff * skb,struct tcmsg * tcm)1074 static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1075 struct sk_buff *skb, struct tcmsg *tcm)
1076 {
1077 struct netem_sched_data *q = qdisc_priv(sch);
1078
1079 if (cl != 1 || !q->qdisc) /* only one class */
1080 return -ENOENT;
1081
1082 tcm->tcm_handle |= TC_H_MIN(1);
1083 tcm->tcm_info = q->qdisc->handle;
1084
1085 return 0;
1086 }
1087
netem_graft(struct Qdisc * sch,unsigned long arg,struct Qdisc * new,struct Qdisc ** old)1088 static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1089 struct Qdisc **old)
1090 {
1091 struct netem_sched_data *q = qdisc_priv(sch);
1092
1093 *old = qdisc_replace(sch, new, &q->qdisc);
1094 return 0;
1095 }
1096
netem_leaf(struct Qdisc * sch,unsigned long arg)1097 static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1098 {
1099 struct netem_sched_data *q = qdisc_priv(sch);
1100 return q->qdisc;
1101 }
1102
netem_get(struct Qdisc * sch,u32 classid)1103 static unsigned long netem_get(struct Qdisc *sch, u32 classid)
1104 {
1105 return 1;
1106 }
1107
netem_put(struct Qdisc * sch,unsigned long arg)1108 static void netem_put(struct Qdisc *sch, unsigned long arg)
1109 {
1110 }
1111
netem_walk(struct Qdisc * sch,struct qdisc_walker * walker)1112 static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1113 {
1114 if (!walker->stop) {
1115 if (walker->count >= walker->skip)
1116 if (walker->fn(sch, 1, walker) < 0) {
1117 walker->stop = 1;
1118 return;
1119 }
1120 walker->count++;
1121 }
1122 }
1123
1124 static const struct Qdisc_class_ops netem_class_ops = {
1125 .graft = netem_graft,
1126 .leaf = netem_leaf,
1127 .get = netem_get,
1128 .put = netem_put,
1129 .walk = netem_walk,
1130 .dump = netem_dump_class,
1131 };
1132
1133 static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1134 .id = "netem",
1135 .cl_ops = &netem_class_ops,
1136 .priv_size = sizeof(struct netem_sched_data),
1137 .enqueue = netem_enqueue,
1138 .dequeue = netem_dequeue,
1139 .peek = qdisc_peek_dequeued,
1140 .init = netem_init,
1141 .reset = netem_reset,
1142 .destroy = netem_destroy,
1143 .change = netem_change,
1144 .dump = netem_dump,
1145 .owner = THIS_MODULE,
1146 };
1147
1148
netem_module_init(void)1149 static int __init netem_module_init(void)
1150 {
1151 pr_info("netem: version " VERSION "\n");
1152 return register_qdisc(&netem_qdisc_ops);
1153 }
netem_module_exit(void)1154 static void __exit netem_module_exit(void)
1155 {
1156 unregister_qdisc(&netem_qdisc_ops);
1157 }
1158 module_init(netem_module_init)
1159 module_exit(netem_module_exit)
1160 MODULE_LICENSE("GPL");
1161