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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * net/sched/sch_netem.c Network emulator
4 *
5 * Many of the algorithms and ideas for this came from
6 * NIST Net which is not copyrighted.
7 *
8 * Authors: Stephen Hemminger <shemminger@osdl.org>
9 * Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
10 */
11
12#include <linux/mm.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/types.h>
16#include <linux/kernel.h>
17#include <linux/errno.h>
18#include <linux/skbuff.h>
19#include <linux/vmalloc.h>
20#include <linux/prandom.h>
21#include <linux/rtnetlink.h>
22#include <linux/reciprocal_div.h>
23#include <linux/rbtree.h>
24
25#include <net/gso.h>
26#include <net/netlink.h>
27#include <net/pkt_sched.h>
28#include <net/inet_ecn.h>
29
30#define VERSION "1.3"
31
32/* Network Emulation Queuing algorithm.
33 ====================================
34
35 Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
36 Network Emulation Tool
37 [2] Luigi Rizzo, DummyNet for FreeBSD
38
39 ----------------------------------------------------------------
40
41 This started out as a simple way to delay outgoing packets to
42 test TCP but has grown to include most of the functionality
43 of a full blown network emulator like NISTnet. It can delay
44 packets and add random jitter (and correlation). The random
45 distribution can be loaded from a table as well to provide
46 normal, Pareto, or experimental curves. Packet loss,
47 duplication, and reordering can also be emulated.
48
49 This qdisc does not do classification that can be handled in
50 layering other disciplines. It does not need to do bandwidth
51 control either since that can be handled by using token
52 bucket or other rate control.
53
54 Correlated Loss Generator models
55
56 Added generation of correlated loss according to the
57 "Gilbert-Elliot" model, a 4-state markov model.
58
59 References:
60 [1] NetemCLG Home http://netgroup.uniroma2.it/NetemCLG
61 [2] S. Salsano, F. Ludovici, A. Ordine, "Definition of a general
62 and intuitive loss model for packet networks and its implementation
63 in the Netem module in the Linux kernel", available in [1]
64
65 Authors: Stefano Salsano <stefano.salsano at uniroma2.it
66 Fabio Ludovici <fabio.ludovici at yahoo.it>
67*/
68
69struct disttable {
70 u32 size;
71 s16 table[] __counted_by(size);
72};
73
74struct netem_sched_data {
75 /* internal t(ime)fifo qdisc uses t_root and sch->limit */
76 struct rb_root t_root;
77
78 /* a linear queue; reduces rbtree rebalancing when jitter is low */
79 struct sk_buff *t_head;
80 struct sk_buff *t_tail;
81
82 u32 t_len;
83
84 /* optional qdisc for classful handling (NULL at netem init) */
85 struct Qdisc *qdisc;
86
87 struct qdisc_watchdog watchdog;
88
89 s64 latency;
90 s64 jitter;
91
92 u32 loss;
93 u32 ecn;
94 u32 limit;
95 u32 counter;
96 u32 gap;
97 u32 duplicate;
98 u32 reorder;
99 u32 corrupt;
100 u64 rate;
101 s32 packet_overhead;
102 u32 cell_size;
103 struct reciprocal_value cell_size_reciprocal;
104 s32 cell_overhead;
105
106 struct crndstate {
107 u32 last;
108 u32 rho;
109 } delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
110
111 struct prng {
112 u64 seed;
113 struct rnd_state prng_state;
114 } prng;
115
116 struct disttable *delay_dist;
117
118 enum {
119 CLG_RANDOM,
120 CLG_4_STATES,
121 CLG_GILB_ELL,
122 } loss_model;
123
124 enum {
125 TX_IN_GAP_PERIOD = 1,
126 TX_IN_BURST_PERIOD,
127 LOST_IN_GAP_PERIOD,
128 LOST_IN_BURST_PERIOD,
129 } _4_state_model;
130
131 enum {
132 GOOD_STATE = 1,
133 BAD_STATE,
134 } GE_state_model;
135
136 /* Correlated Loss Generation models */
137 struct clgstate {
138 /* state of the Markov chain */
139 u8 state;
140
141 /* 4-states and Gilbert-Elliot models */
142 u32 a1; /* p13 for 4-states or p for GE */
143 u32 a2; /* p31 for 4-states or r for GE */
144 u32 a3; /* p32 for 4-states or h for GE */
145 u32 a4; /* p14 for 4-states or 1-k for GE */
146 u32 a5; /* p23 used only in 4-states */
147 } clg;
148
149 struct tc_netem_slot slot_config;
150 struct slotstate {
151 u64 slot_next;
152 s32 packets_left;
153 s32 bytes_left;
154 } slot;
155
156 struct disttable *slot_dist;
157};
158
159/* Time stamp put into socket buffer control block
160 * Only valid when skbs are in our internal t(ime)fifo queue.
161 *
162 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,
163 * and skb->next & skb->prev are scratch space for a qdisc,
164 * we save skb->tstamp value in skb->cb[] before destroying it.
165 */
166struct netem_skb_cb {
167 u64 time_to_send;
168};
169
170static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
171{
172 /* we assume we can use skb next/prev/tstamp as storage for rb_node */
173 qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb));
174 return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data;
175}
176
177/* init_crandom - initialize correlated random number generator
178 * Use entropy source for initial seed.
179 */
180static void init_crandom(struct crndstate *state, unsigned long rho)
181{
182 state->rho = rho;
183 state->last = get_random_u32();
184}
185
186/* get_crandom - correlated random number generator
187 * Next number depends on last value.
188 * rho is scaled to avoid floating point.
189 */
190static u32 get_crandom(struct crndstate *state, struct prng *p)
191{
192 u64 value, rho;
193 unsigned long answer;
194 struct rnd_state *s = &p->prng_state;
195
196 if (!state || state->rho == 0) /* no correlation */
197 return prandom_u32_state(s);
198
199 value = prandom_u32_state(s);
200 rho = (u64)state->rho + 1;
201 answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
202 state->last = answer;
203 return answer;
204}
205
206/* loss_4state - 4-state model loss generator
207 * Generates losses according to the 4-state Markov chain adopted in
208 * the GI (General and Intuitive) loss model.
209 */
210static bool loss_4state(struct netem_sched_data *q)
211{
212 struct clgstate *clg = &q->clg;
213 u32 rnd = prandom_u32_state(&q->prng.prng_state);
214
215 /*
216 * Makes a comparison between rnd and the transition
217 * probabilities outgoing from the current state, then decides the
218 * next state and if the next packet has to be transmitted or lost.
219 * The four states correspond to:
220 * TX_IN_GAP_PERIOD => successfully transmitted packets within a gap period
221 * LOST_IN_GAP_PERIOD => isolated losses within a gap period
222 * LOST_IN_BURST_PERIOD => lost packets within a burst period
223 * TX_IN_BURST_PERIOD => successfully transmitted packets within a burst period
224 */
225 switch (clg->state) {
226 case TX_IN_GAP_PERIOD:
227 if (rnd < clg->a4) {
228 clg->state = LOST_IN_GAP_PERIOD;
229 return true;
230 } else if (clg->a4 < rnd && rnd < clg->a1 + clg->a4) {
231 clg->state = LOST_IN_BURST_PERIOD;
232 return true;
233 } else if (clg->a1 + clg->a4 < rnd) {
234 clg->state = TX_IN_GAP_PERIOD;
235 }
236
237 break;
238 case TX_IN_BURST_PERIOD:
239 if (rnd < clg->a5) {
240 clg->state = LOST_IN_BURST_PERIOD;
241 return true;
242 } else {
243 clg->state = TX_IN_BURST_PERIOD;
244 }
245
246 break;
247 case LOST_IN_BURST_PERIOD:
248 if (rnd < clg->a3)
249 clg->state = TX_IN_BURST_PERIOD;
250 else if (clg->a3 < rnd && rnd < clg->a2 + clg->a3) {
251 clg->state = TX_IN_GAP_PERIOD;
252 } else if (clg->a2 + clg->a3 < rnd) {
253 clg->state = LOST_IN_BURST_PERIOD;
254 return true;
255 }
256 break;
257 case LOST_IN_GAP_PERIOD:
258 clg->state = TX_IN_GAP_PERIOD;
259 break;
260 }
261
262 return false;
263}
264
265/* loss_gilb_ell - Gilbert-Elliot model loss generator
266 * Generates losses according to the Gilbert-Elliot loss model or
267 * its special cases (Gilbert or Simple Gilbert)
268 *
269 * Makes a comparison between random number and the transition
270 * probabilities outgoing from the current state, then decides the
271 * next state. A second random number is extracted and the comparison
272 * with the loss probability of the current state decides if the next
273 * packet will be transmitted or lost.
274 */
275static bool loss_gilb_ell(struct netem_sched_data *q)
276{
277 struct clgstate *clg = &q->clg;
278 struct rnd_state *s = &q->prng.prng_state;
279
280 switch (clg->state) {
281 case GOOD_STATE:
282 if (prandom_u32_state(s) < clg->a1)
283 clg->state = BAD_STATE;
284 if (prandom_u32_state(s) < clg->a4)
285 return true;
286 break;
287 case BAD_STATE:
288 if (prandom_u32_state(s) < clg->a2)
289 clg->state = GOOD_STATE;
290 if (prandom_u32_state(s) > clg->a3)
291 return true;
292 }
293
294 return false;
295}
296
297static bool loss_event(struct netem_sched_data *q)
298{
299 switch (q->loss_model) {
300 case CLG_RANDOM:
301 /* Random packet drop 0 => none, ~0 => all */
302 return q->loss && q->loss >= get_crandom(&q->loss_cor, &q->prng);
303
304 case CLG_4_STATES:
305 /* 4state loss model algorithm (used also for GI model)
306 * Extracts a value from the markov 4 state loss generator,
307 * if it is 1 drops a packet and if needed writes the event in
308 * the kernel logs
309 */
310 return loss_4state(q);
311
312 case CLG_GILB_ELL:
313 /* Gilbert-Elliot loss model algorithm
314 * Extracts a value from the Gilbert-Elliot loss generator,
315 * if it is 1 drops a packet and if needed writes the event in
316 * the kernel logs
317 */
318 return loss_gilb_ell(q);
319 }
320
321 return false; /* not reached */
322}
323
324
325/* tabledist - return a pseudo-randomly distributed value with mean mu and
326 * std deviation sigma. Uses table lookup to approximate the desired
327 * distribution, and a uniformly-distributed pseudo-random source.
328 */
329static s64 tabledist(s64 mu, s32 sigma,
330 struct crndstate *state,
331 struct prng *prng,
332 const struct disttable *dist)
333{
334 s64 x;
335 long t;
336 u32 rnd;
337
338 if (sigma == 0)
339 return mu;
340
341 rnd = get_crandom(state, prng);
342
343 /* default uniform distribution */
344 if (dist == NULL)
345 return ((rnd % (2 * (u32)sigma)) + mu) - sigma;
346
347 t = dist->table[rnd % dist->size];
348 x = (sigma % NETEM_DIST_SCALE) * t;
349 if (x >= 0)
350 x += NETEM_DIST_SCALE/2;
351 else
352 x -= NETEM_DIST_SCALE/2;
353
354 return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
355}
356
357static u64 packet_time_ns(u64 len, const struct netem_sched_data *q)
358{
359 len += q->packet_overhead;
360
361 if (q->cell_size) {
362 u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
363
364 if (len > cells * q->cell_size) /* extra cell needed for remainder */
365 cells++;
366 len = cells * (q->cell_size + q->cell_overhead);
367 }
368
369 return div64_u64(len * NSEC_PER_SEC, q->rate);
370}
371
372static void tfifo_reset(struct Qdisc *sch)
373{
374 struct netem_sched_data *q = qdisc_priv(sch);
375 struct rb_node *p = rb_first(&q->t_root);
376
377 while (p) {
378 struct sk_buff *skb = rb_to_skb(p);
379
380 p = rb_next(p);
381 rb_erase(&skb->rbnode, &q->t_root);
382 rtnl_kfree_skbs(skb, skb);
383 }
384
385 rtnl_kfree_skbs(q->t_head, q->t_tail);
386 q->t_head = NULL;
387 q->t_tail = NULL;
388 q->t_len = 0;
389}
390
391static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
392{
393 struct netem_sched_data *q = qdisc_priv(sch);
394 u64 tnext = netem_skb_cb(nskb)->time_to_send;
395
396 if (!q->t_tail || tnext >= netem_skb_cb(q->t_tail)->time_to_send) {
397 if (q->t_tail)
398 q->t_tail->next = nskb;
399 else
400 q->t_head = nskb;
401 q->t_tail = nskb;
402 } else {
403 struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
404
405 while (*p) {
406 struct sk_buff *skb;
407
408 parent = *p;
409 skb = rb_to_skb(parent);
410 if (tnext >= netem_skb_cb(skb)->time_to_send)
411 p = &parent->rb_right;
412 else
413 p = &parent->rb_left;
414 }
415 rb_link_node(&nskb->rbnode, parent, p);
416 rb_insert_color(&nskb->rbnode, &q->t_root);
417 }
418 q->t_len++;
419 sch->q.qlen++;
420}
421
422/* netem can't properly corrupt a megapacket (like we get from GSO), so instead
423 * when we statistically choose to corrupt one, we instead segment it, returning
424 * the first packet to be corrupted, and re-enqueue the remaining frames
425 */
426static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch,
427 struct sk_buff **to_free)
428{
429 struct sk_buff *segs;
430 netdev_features_t features = netif_skb_features(skb);
431
432 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
433
434 if (IS_ERR_OR_NULL(segs)) {
435 qdisc_drop(skb, sch, to_free);
436 return NULL;
437 }
438 consume_skb(skb);
439 return segs;
440}
441
442/*
443 * Insert one skb into qdisc.
444 * Note: parent depends on return value to account for queue length.
445 * NET_XMIT_DROP: queue length didn't change.
446 * NET_XMIT_SUCCESS: one skb was queued.
447 */
448static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
449 struct sk_buff **to_free)
450{
451 struct netem_sched_data *q = qdisc_priv(sch);
452 /* We don't fill cb now as skb_unshare() may invalidate it */
453 struct netem_skb_cb *cb;
454 struct sk_buff *skb2 = NULL;
455 struct sk_buff *segs = NULL;
456 unsigned int prev_len = qdisc_pkt_len(skb);
457 int count = 1;
458
459 /* Do not fool qdisc_drop_all() */
460 skb->prev = NULL;
461
462 /* Random duplication */
463 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor, &q->prng))
464 ++count;
465
466 /* Drop packet? */
467 if (loss_event(q)) {
468 if (q->ecn && INET_ECN_set_ce(skb))
469 qdisc_qstats_drop(sch); /* mark packet */
470 else
471 --count;
472 }
473 if (count == 0) {
474 qdisc_qstats_drop(sch);
475 __qdisc_drop(skb, to_free);
476 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
477 }
478
479 /* If a delay is expected, orphan the skb. (orphaning usually takes
480 * place at TX completion time, so _before_ the link transit delay)
481 */
482 if (q->latency || q->jitter || q->rate)
483 skb_orphan_partial(skb);
484
485 /*
486 * If we need to duplicate packet, then clone it before
487 * original is modified.
488 */
489 if (count > 1)
490 skb2 = skb_clone(skb, GFP_ATOMIC);
491
492 /*
493 * Randomized packet corruption.
494 * Make copy if needed since we are modifying
495 * If packet is going to be hardware checksummed, then
496 * do it now in software before we mangle it.
497 */
498 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor, &q->prng)) {
499 if (skb_is_gso(skb)) {
500 skb = netem_segment(skb, sch, to_free);
501 if (!skb)
502 goto finish_segs;
503
504 segs = skb->next;
505 skb_mark_not_on_list(skb);
506 qdisc_skb_cb(skb)->pkt_len = skb->len;
507 }
508
509 skb = skb_unshare(skb, GFP_ATOMIC);
510 if (unlikely(!skb)) {
511 qdisc_qstats_drop(sch);
512 goto finish_segs;
513 }
514 if (skb->ip_summed == CHECKSUM_PARTIAL &&
515 skb_checksum_help(skb)) {
516 qdisc_drop(skb, sch, to_free);
517 skb = NULL;
518 goto finish_segs;
519 }
520
521 skb->data[get_random_u32_below(skb_headlen(skb))] ^=
522 1<<get_random_u32_below(8);
523 }
524
525 if (unlikely(q->t_len >= sch->limit)) {
526 /* re-link segs, so that qdisc_drop_all() frees them all */
527 skb->next = segs;
528 qdisc_drop_all(skb, sch, to_free);
529 if (skb2)
530 __qdisc_drop(skb2, to_free);
531 return NET_XMIT_DROP;
532 }
533
534 /*
535 * If doing duplication then re-insert at top of the
536 * qdisc tree, since parent queuer expects that only one
537 * skb will be queued.
538 */
539 if (skb2) {
540 struct Qdisc *rootq = qdisc_root_bh(sch);
541 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
542
543 q->duplicate = 0;
544 rootq->enqueue(skb2, rootq, to_free);
545 q->duplicate = dupsave;
546 skb2 = NULL;
547 }
548
549 qdisc_qstats_backlog_inc(sch, skb);
550
551 cb = netem_skb_cb(skb);
552 if (q->gap == 0 || /* not doing reordering */
553 q->counter < q->gap - 1 || /* inside last reordering gap */
554 q->reorder < get_crandom(&q->reorder_cor, &q->prng)) {
555 u64 now;
556 s64 delay;
557
558 delay = tabledist(q->latency, q->jitter,
559 &q->delay_cor, &q->prng, q->delay_dist);
560
561 now = ktime_get_ns();
562
563 if (q->rate) {
564 struct netem_skb_cb *last = NULL;
565
566 if (sch->q.tail)
567 last = netem_skb_cb(sch->q.tail);
568 if (q->t_root.rb_node) {
569 struct sk_buff *t_skb;
570 struct netem_skb_cb *t_last;
571
572 t_skb = skb_rb_last(&q->t_root);
573 t_last = netem_skb_cb(t_skb);
574 if (!last ||
575 t_last->time_to_send > last->time_to_send)
576 last = t_last;
577 }
578 if (q->t_tail) {
579 struct netem_skb_cb *t_last =
580 netem_skb_cb(q->t_tail);
581
582 if (!last ||
583 t_last->time_to_send > last->time_to_send)
584 last = t_last;
585 }
586
587 if (last) {
588 /*
589 * Last packet in queue is reference point (now),
590 * calculate this time bonus and subtract
591 * from delay.
592 */
593 delay -= last->time_to_send - now;
594 delay = max_t(s64, 0, delay);
595 now = last->time_to_send;
596 }
597
598 delay += packet_time_ns(qdisc_pkt_len(skb), q);
599 }
600
601 cb->time_to_send = now + delay;
602 ++q->counter;
603 tfifo_enqueue(skb, sch);
604 } else {
605 /*
606 * Do re-ordering by putting one out of N packets at the front
607 * of the queue.
608 */
609 cb->time_to_send = ktime_get_ns();
610 q->counter = 0;
611
612 __qdisc_enqueue_head(skb, &sch->q);
613 sch->qstats.requeues++;
614 }
615
616finish_segs:
617 if (skb2)
618 __qdisc_drop(skb2, to_free);
619
620 if (segs) {
621 unsigned int len, last_len;
622 int rc, nb;
623
624 len = skb ? skb->len : 0;
625 nb = skb ? 1 : 0;
626
627 while (segs) {
628 skb2 = segs->next;
629 skb_mark_not_on_list(segs);
630 qdisc_skb_cb(segs)->pkt_len = segs->len;
631 last_len = segs->len;
632 rc = qdisc_enqueue(segs, sch, to_free);
633 if (rc != NET_XMIT_SUCCESS) {
634 if (net_xmit_drop_count(rc))
635 qdisc_qstats_drop(sch);
636 } else {
637 nb++;
638 len += last_len;
639 }
640 segs = skb2;
641 }
642 /* Parent qdiscs accounted for 1 skb of size @prev_len */
643 qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
644 } else if (!skb) {
645 return NET_XMIT_DROP;
646 }
647 return NET_XMIT_SUCCESS;
648}
649
650/* Delay the next round with a new future slot with a
651 * correct number of bytes and packets.
652 */
653
654static void get_slot_next(struct netem_sched_data *q, u64 now)
655{
656 s64 next_delay;
657
658 if (!q->slot_dist)
659 next_delay = q->slot_config.min_delay +
660 (get_random_u32() *
661 (q->slot_config.max_delay -
662 q->slot_config.min_delay) >> 32);
663 else
664 next_delay = tabledist(q->slot_config.dist_delay,
665 (s32)(q->slot_config.dist_jitter),
666 NULL, &q->prng, q->slot_dist);
667
668 q->slot.slot_next = now + next_delay;
669 q->slot.packets_left = q->slot_config.max_packets;
670 q->slot.bytes_left = q->slot_config.max_bytes;
671}
672
673static struct sk_buff *netem_peek(struct netem_sched_data *q)
674{
675 struct sk_buff *skb = skb_rb_first(&q->t_root);
676 u64 t1, t2;
677
678 if (!skb)
679 return q->t_head;
680 if (!q->t_head)
681 return skb;
682
683 t1 = netem_skb_cb(skb)->time_to_send;
684 t2 = netem_skb_cb(q->t_head)->time_to_send;
685 if (t1 < t2)
686 return skb;
687 return q->t_head;
688}
689
690static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb)
691{
692 if (skb == q->t_head) {
693 q->t_head = skb->next;
694 if (!q->t_head)
695 q->t_tail = NULL;
696 } else {
697 rb_erase(&skb->rbnode, &q->t_root);
698 }
699}
700
701static struct sk_buff *netem_dequeue(struct Qdisc *sch)
702{
703 struct netem_sched_data *q = qdisc_priv(sch);
704 struct sk_buff *skb;
705
706tfifo_dequeue:
707 skb = __qdisc_dequeue_head(&sch->q);
708 if (skb) {
709deliver:
710 qdisc_qstats_backlog_dec(sch, skb);
711 qdisc_bstats_update(sch, skb);
712 return skb;
713 }
714 skb = netem_peek(q);
715 if (skb) {
716 u64 time_to_send;
717 u64 now = ktime_get_ns();
718
719 /* if more time remaining? */
720 time_to_send = netem_skb_cb(skb)->time_to_send;
721 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
722 get_slot_next(q, now);
723
724 if (time_to_send <= now && q->slot.slot_next <= now) {
725 netem_erase_head(q, skb);
726 q->t_len--;
727 skb->next = NULL;
728 skb->prev = NULL;
729 /* skb->dev shares skb->rbnode area,
730 * we need to restore its value.
731 */
732 skb->dev = qdisc_dev(sch);
733
734 if (q->slot.slot_next) {
735 q->slot.packets_left--;
736 q->slot.bytes_left -= qdisc_pkt_len(skb);
737 if (q->slot.packets_left <= 0 ||
738 q->slot.bytes_left <= 0)
739 get_slot_next(q, now);
740 }
741
742 if (q->qdisc) {
743 unsigned int pkt_len = qdisc_pkt_len(skb);
744 struct sk_buff *to_free = NULL;
745 int err;
746
747 err = qdisc_enqueue(skb, q->qdisc, &to_free);
748 kfree_skb_list(to_free);
749 if (err != NET_XMIT_SUCCESS) {
750 if (net_xmit_drop_count(err))
751 qdisc_qstats_drop(sch);
752 sch->qstats.backlog -= pkt_len;
753 sch->q.qlen--;
754 qdisc_tree_reduce_backlog(sch, 1, pkt_len);
755 }
756 goto tfifo_dequeue;
757 }
758 sch->q.qlen--;
759 goto deliver;
760 }
761
762 if (q->qdisc) {
763 skb = q->qdisc->ops->dequeue(q->qdisc);
764 if (skb) {
765 sch->q.qlen--;
766 goto deliver;
767 }
768 }
769
770 qdisc_watchdog_schedule_ns(&q->watchdog,
771 max(time_to_send,
772 q->slot.slot_next));
773 }
774
775 if (q->qdisc) {
776 skb = q->qdisc->ops->dequeue(q->qdisc);
777 if (skb) {
778 sch->q.qlen--;
779 goto deliver;
780 }
781 }
782 return NULL;
783}
784
785static void netem_reset(struct Qdisc *sch)
786{
787 struct netem_sched_data *q = qdisc_priv(sch);
788
789 qdisc_reset_queue(sch);
790 tfifo_reset(sch);
791 if (q->qdisc)
792 qdisc_reset(q->qdisc);
793 qdisc_watchdog_cancel(&q->watchdog);
794}
795
796static void dist_free(struct disttable *d)
797{
798 kvfree(d);
799}
800
801/*
802 * Distribution data is a variable size payload containing
803 * signed 16 bit values.
804 */
805
806static int get_dist_table(struct disttable **tbl, const struct nlattr *attr)
807{
808 size_t n = nla_len(attr)/sizeof(__s16);
809 const __s16 *data = nla_data(attr);
810 struct disttable *d;
811 int i;
812
813 if (!n || n > NETEM_DIST_MAX)
814 return -EINVAL;
815
816 d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
817 if (!d)
818 return -ENOMEM;
819
820 d->size = n;
821 for (i = 0; i < n; i++)
822 d->table[i] = data[i];
823
824 *tbl = d;
825 return 0;
826}
827
828static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
829{
830 const struct tc_netem_slot *c = nla_data(attr);
831
832 q->slot_config = *c;
833 if (q->slot_config.max_packets == 0)
834 q->slot_config.max_packets = INT_MAX;
835 if (q->slot_config.max_bytes == 0)
836 q->slot_config.max_bytes = INT_MAX;
837
838 /* capping dist_jitter to the range acceptable by tabledist() */
839 q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter));
840
841 q->slot.packets_left = q->slot_config.max_packets;
842 q->slot.bytes_left = q->slot_config.max_bytes;
843 if (q->slot_config.min_delay | q->slot_config.max_delay |
844 q->slot_config.dist_jitter)
845 q->slot.slot_next = ktime_get_ns();
846 else
847 q->slot.slot_next = 0;
848}
849
850static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
851{
852 const struct tc_netem_corr *c = nla_data(attr);
853
854 init_crandom(&q->delay_cor, c->delay_corr);
855 init_crandom(&q->loss_cor, c->loss_corr);
856 init_crandom(&q->dup_cor, c->dup_corr);
857}
858
859static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
860{
861 const struct tc_netem_reorder *r = nla_data(attr);
862
863 q->reorder = r->probability;
864 init_crandom(&q->reorder_cor, r->correlation);
865}
866
867static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
868{
869 const struct tc_netem_corrupt *r = nla_data(attr);
870
871 q->corrupt = r->probability;
872 init_crandom(&q->corrupt_cor, r->correlation);
873}
874
875static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
876{
877 const struct tc_netem_rate *r = nla_data(attr);
878
879 q->rate = r->rate;
880 q->packet_overhead = r->packet_overhead;
881 q->cell_size = r->cell_size;
882 q->cell_overhead = r->cell_overhead;
883 if (q->cell_size)
884 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
885 else
886 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
887}
888
889static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
890{
891 const struct nlattr *la;
892 int rem;
893
894 nla_for_each_nested(la, attr, rem) {
895 u16 type = nla_type(la);
896
897 switch (type) {
898 case NETEM_LOSS_GI: {
899 const struct tc_netem_gimodel *gi = nla_data(la);
900
901 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
902 pr_info("netem: incorrect gi model size\n");
903 return -EINVAL;
904 }
905
906 q->loss_model = CLG_4_STATES;
907
908 q->clg.state = TX_IN_GAP_PERIOD;
909 q->clg.a1 = gi->p13;
910 q->clg.a2 = gi->p31;
911 q->clg.a3 = gi->p32;
912 q->clg.a4 = gi->p14;
913 q->clg.a5 = gi->p23;
914 break;
915 }
916
917 case NETEM_LOSS_GE: {
918 const struct tc_netem_gemodel *ge = nla_data(la);
919
920 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
921 pr_info("netem: incorrect ge model size\n");
922 return -EINVAL;
923 }
924
925 q->loss_model = CLG_GILB_ELL;
926 q->clg.state = GOOD_STATE;
927 q->clg.a1 = ge->p;
928 q->clg.a2 = ge->r;
929 q->clg.a3 = ge->h;
930 q->clg.a4 = ge->k1;
931 break;
932 }
933
934 default:
935 pr_info("netem: unknown loss type %u\n", type);
936 return -EINVAL;
937 }
938 }
939
940 return 0;
941}
942
943static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
944 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
945 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
946 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
947 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
948 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
949 [TCA_NETEM_ECN] = { .type = NLA_U32 },
950 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
951 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
952 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
953 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
954 [TCA_NETEM_PRNG_SEED] = { .type = NLA_U64 },
955};
956
957static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
958 const struct nla_policy *policy, int len)
959{
960 int nested_len = nla_len(nla) - NLA_ALIGN(len);
961
962 if (nested_len < 0) {
963 pr_info("netem: invalid attributes len %d\n", nested_len);
964 return -EINVAL;
965 }
966
967 if (nested_len >= nla_attr_size(0))
968 return nla_parse_deprecated(tb, maxtype,
969 nla_data(nla) + NLA_ALIGN(len),
970 nested_len, policy, NULL);
971
972 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
973 return 0;
974}
975
976/* Parse netlink message to set options */
977static int netem_change(struct Qdisc *sch, struct nlattr *opt,
978 struct netlink_ext_ack *extack)
979{
980 struct netem_sched_data *q = qdisc_priv(sch);
981 struct nlattr *tb[TCA_NETEM_MAX + 1];
982 struct disttable *delay_dist = NULL;
983 struct disttable *slot_dist = NULL;
984 struct tc_netem_qopt *qopt;
985 struct clgstate old_clg;
986 int old_loss_model = CLG_RANDOM;
987 int ret;
988
989 qopt = nla_data(opt);
990 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
991 if (ret < 0)
992 return ret;
993
994 if (tb[TCA_NETEM_DELAY_DIST]) {
995 ret = get_dist_table(&delay_dist, tb[TCA_NETEM_DELAY_DIST]);
996 if (ret)
997 goto table_free;
998 }
999
1000 if (tb[TCA_NETEM_SLOT_DIST]) {
1001 ret = get_dist_table(&slot_dist, tb[TCA_NETEM_SLOT_DIST]);
1002 if (ret)
1003 goto table_free;
1004 }
1005
1006 sch_tree_lock(sch);
1007 /* backup q->clg and q->loss_model */
1008 old_clg = q->clg;
1009 old_loss_model = q->loss_model;
1010
1011 if (tb[TCA_NETEM_LOSS]) {
1012 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
1013 if (ret) {
1014 q->loss_model = old_loss_model;
1015 q->clg = old_clg;
1016 goto unlock;
1017 }
1018 } else {
1019 q->loss_model = CLG_RANDOM;
1020 }
1021
1022 if (delay_dist)
1023 swap(q->delay_dist, delay_dist);
1024 if (slot_dist)
1025 swap(q->slot_dist, slot_dist);
1026 sch->limit = qopt->limit;
1027
1028 q->latency = PSCHED_TICKS2NS(qopt->latency);
1029 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
1030 q->limit = qopt->limit;
1031 q->gap = qopt->gap;
1032 q->counter = 0;
1033 q->loss = qopt->loss;
1034 q->duplicate = qopt->duplicate;
1035
1036 /* for compatibility with earlier versions.
1037 * if gap is set, need to assume 100% probability
1038 */
1039 if (q->gap)
1040 q->reorder = ~0;
1041
1042 if (tb[TCA_NETEM_CORR])
1043 get_correlation(q, tb[TCA_NETEM_CORR]);
1044
1045 if (tb[TCA_NETEM_REORDER])
1046 get_reorder(q, tb[TCA_NETEM_REORDER]);
1047
1048 if (tb[TCA_NETEM_CORRUPT])
1049 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
1050
1051 if (tb[TCA_NETEM_RATE])
1052 get_rate(q, tb[TCA_NETEM_RATE]);
1053
1054 if (tb[TCA_NETEM_RATE64])
1055 q->rate = max_t(u64, q->rate,
1056 nla_get_u64(tb[TCA_NETEM_RATE64]));
1057
1058 if (tb[TCA_NETEM_LATENCY64])
1059 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
1060
1061 if (tb[TCA_NETEM_JITTER64])
1062 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
1063
1064 if (tb[TCA_NETEM_ECN])
1065 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
1066
1067 if (tb[TCA_NETEM_SLOT])
1068 get_slot(q, tb[TCA_NETEM_SLOT]);
1069
1070 /* capping jitter to the range acceptable by tabledist() */
1071 q->jitter = min_t(s64, abs(q->jitter), INT_MAX);
1072
1073 if (tb[TCA_NETEM_PRNG_SEED])
1074 q->prng.seed = nla_get_u64(tb[TCA_NETEM_PRNG_SEED]);
1075 else
1076 q->prng.seed = get_random_u64();
1077 prandom_seed_state(&q->prng.prng_state, q->prng.seed);
1078
1079unlock:
1080 sch_tree_unlock(sch);
1081
1082table_free:
1083 dist_free(delay_dist);
1084 dist_free(slot_dist);
1085 return ret;
1086}
1087
1088static int netem_init(struct Qdisc *sch, struct nlattr *opt,
1089 struct netlink_ext_ack *extack)
1090{
1091 struct netem_sched_data *q = qdisc_priv(sch);
1092 int ret;
1093
1094 qdisc_watchdog_init(&q->watchdog, sch);
1095
1096 if (!opt)
1097 return -EINVAL;
1098
1099 q->loss_model = CLG_RANDOM;
1100 ret = netem_change(sch, opt, extack);
1101 if (ret)
1102 pr_info("netem: change failed\n");
1103 return ret;
1104}
1105
1106static void netem_destroy(struct Qdisc *sch)
1107{
1108 struct netem_sched_data *q = qdisc_priv(sch);
1109
1110 qdisc_watchdog_cancel(&q->watchdog);
1111 if (q->qdisc)
1112 qdisc_put(q->qdisc);
1113 dist_free(q->delay_dist);
1114 dist_free(q->slot_dist);
1115}
1116
1117static int dump_loss_model(const struct netem_sched_data *q,
1118 struct sk_buff *skb)
1119{
1120 struct nlattr *nest;
1121
1122 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
1123 if (nest == NULL)
1124 goto nla_put_failure;
1125
1126 switch (q->loss_model) {
1127 case CLG_RANDOM:
1128 /* legacy loss model */
1129 nla_nest_cancel(skb, nest);
1130 return 0; /* no data */
1131
1132 case CLG_4_STATES: {
1133 struct tc_netem_gimodel gi = {
1134 .p13 = q->clg.a1,
1135 .p31 = q->clg.a2,
1136 .p32 = q->clg.a3,
1137 .p14 = q->clg.a4,
1138 .p23 = q->clg.a5,
1139 };
1140
1141 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1142 goto nla_put_failure;
1143 break;
1144 }
1145 case CLG_GILB_ELL: {
1146 struct tc_netem_gemodel ge = {
1147 .p = q->clg.a1,
1148 .r = q->clg.a2,
1149 .h = q->clg.a3,
1150 .k1 = q->clg.a4,
1151 };
1152
1153 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1154 goto nla_put_failure;
1155 break;
1156 }
1157 }
1158
1159 nla_nest_end(skb, nest);
1160 return 0;
1161
1162nla_put_failure:
1163 nla_nest_cancel(skb, nest);
1164 return -1;
1165}
1166
1167static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1168{
1169 const struct netem_sched_data *q = qdisc_priv(sch);
1170 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1171 struct tc_netem_qopt qopt;
1172 struct tc_netem_corr cor;
1173 struct tc_netem_reorder reorder;
1174 struct tc_netem_corrupt corrupt;
1175 struct tc_netem_rate rate;
1176 struct tc_netem_slot slot;
1177
1178 qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency),
1179 UINT_MAX);
1180 qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter),
1181 UINT_MAX);
1182 qopt.limit = q->limit;
1183 qopt.loss = q->loss;
1184 qopt.gap = q->gap;
1185 qopt.duplicate = q->duplicate;
1186 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1187 goto nla_put_failure;
1188
1189 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1190 goto nla_put_failure;
1191
1192 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1193 goto nla_put_failure;
1194
1195 cor.delay_corr = q->delay_cor.rho;
1196 cor.loss_corr = q->loss_cor.rho;
1197 cor.dup_corr = q->dup_cor.rho;
1198 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1199 goto nla_put_failure;
1200
1201 reorder.probability = q->reorder;
1202 reorder.correlation = q->reorder_cor.rho;
1203 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1204 goto nla_put_failure;
1205
1206 corrupt.probability = q->corrupt;
1207 corrupt.correlation = q->corrupt_cor.rho;
1208 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1209 goto nla_put_failure;
1210
1211 if (q->rate >= (1ULL << 32)) {
1212 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1213 TCA_NETEM_PAD))
1214 goto nla_put_failure;
1215 rate.rate = ~0U;
1216 } else {
1217 rate.rate = q->rate;
1218 }
1219 rate.packet_overhead = q->packet_overhead;
1220 rate.cell_size = q->cell_size;
1221 rate.cell_overhead = q->cell_overhead;
1222 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1223 goto nla_put_failure;
1224
1225 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1226 goto nla_put_failure;
1227
1228 if (dump_loss_model(q, skb) != 0)
1229 goto nla_put_failure;
1230
1231 if (q->slot_config.min_delay | q->slot_config.max_delay |
1232 q->slot_config.dist_jitter) {
1233 slot = q->slot_config;
1234 if (slot.max_packets == INT_MAX)
1235 slot.max_packets = 0;
1236 if (slot.max_bytes == INT_MAX)
1237 slot.max_bytes = 0;
1238 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1239 goto nla_put_failure;
1240 }
1241
1242 if (nla_put_u64_64bit(skb, TCA_NETEM_PRNG_SEED, q->prng.seed,
1243 TCA_NETEM_PAD))
1244 goto nla_put_failure;
1245
1246 return nla_nest_end(skb, nla);
1247
1248nla_put_failure:
1249 nlmsg_trim(skb, nla);
1250 return -1;
1251}
1252
1253static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1254 struct sk_buff *skb, struct tcmsg *tcm)
1255{
1256 struct netem_sched_data *q = qdisc_priv(sch);
1257
1258 if (cl != 1 || !q->qdisc) /* only one class */
1259 return -ENOENT;
1260
1261 tcm->tcm_handle |= TC_H_MIN(1);
1262 tcm->tcm_info = q->qdisc->handle;
1263
1264 return 0;
1265}
1266
1267static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1268 struct Qdisc **old, struct netlink_ext_ack *extack)
1269{
1270 struct netem_sched_data *q = qdisc_priv(sch);
1271
1272 *old = qdisc_replace(sch, new, &q->qdisc);
1273 return 0;
1274}
1275
1276static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1277{
1278 struct netem_sched_data *q = qdisc_priv(sch);
1279 return q->qdisc;
1280}
1281
1282static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1283{
1284 return 1;
1285}
1286
1287static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1288{
1289 if (!walker->stop) {
1290 if (!tc_qdisc_stats_dump(sch, 1, walker))
1291 return;
1292 }
1293}
1294
1295static const struct Qdisc_class_ops netem_class_ops = {
1296 .graft = netem_graft,
1297 .leaf = netem_leaf,
1298 .find = netem_find,
1299 .walk = netem_walk,
1300 .dump = netem_dump_class,
1301};
1302
1303static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1304 .id = "netem",
1305 .cl_ops = &netem_class_ops,
1306 .priv_size = sizeof(struct netem_sched_data),
1307 .enqueue = netem_enqueue,
1308 .dequeue = netem_dequeue,
1309 .peek = qdisc_peek_dequeued,
1310 .init = netem_init,
1311 .reset = netem_reset,
1312 .destroy = netem_destroy,
1313 .change = netem_change,
1314 .dump = netem_dump,
1315 .owner = THIS_MODULE,
1316};
1317MODULE_ALIAS_NET_SCH("netem");
1318
1319
1320static int __init netem_module_init(void)
1321{
1322 pr_info("netem: version " VERSION "\n");
1323 return register_qdisc(&netem_qdisc_ops);
1324}
1325static void __exit netem_module_exit(void)
1326{
1327 unregister_qdisc(&netem_qdisc_ops);
1328}
1329module_init(netem_module_init)
1330module_exit(netem_module_exit)
1331MODULE_LICENSE("GPL");
1332MODULE_DESCRIPTION("Network characteristics emulator qdisc");
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
68struct disttable {
69 u32 size;
70 s16 table[] __counted_by(size);
71};
72
73struct 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 */
163struct netem_skb_cb {
164 u64 time_to_send;
165};
166
167static 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 */
177static 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 */
187static 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 */
207static 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 */
272static 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
294static 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 */
326static 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
354static 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
369static 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
387static 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 */
421static 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 */
443static 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;
450 struct sk_buff *segs = NULL;
451 unsigned int prev_len = qdisc_pkt_len(skb);
452 int count = 1;
453 int rc = NET_XMIT_SUCCESS;
454 int rc_drop = NET_XMIT_DROP;
455
456 /* Do not fool qdisc_drop_all() */
457 skb->prev = NULL;
458
459 /* Random duplication */
460 if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor, &q->prng))
461 ++count;
462
463 /* Drop packet? */
464 if (loss_event(q)) {
465 if (q->ecn && INET_ECN_set_ce(skb))
466 qdisc_qstats_drop(sch); /* mark packet */
467 else
468 --count;
469 }
470 if (count == 0) {
471 qdisc_qstats_drop(sch);
472 __qdisc_drop(skb, to_free);
473 return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
474 }
475
476 /* If a delay is expected, orphan the skb. (orphaning usually takes
477 * place at TX completion time, so _before_ the link transit delay)
478 */
479 if (q->latency || q->jitter || q->rate)
480 skb_orphan_partial(skb);
481
482 /*
483 * If we need to duplicate packet, then re-insert at top of the
484 * qdisc tree, since parent queuer expects that only one
485 * skb will be queued.
486 */
487 if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
488 struct Qdisc *rootq = qdisc_root_bh(sch);
489 u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
490
491 q->duplicate = 0;
492 rootq->enqueue(skb2, rootq, to_free);
493 q->duplicate = dupsave;
494 rc_drop = NET_XMIT_SUCCESS;
495 }
496
497 /*
498 * Randomized packet corruption.
499 * Make copy if needed since we are modifying
500 * If packet is going to be hardware checksummed, then
501 * do it now in software before we mangle it.
502 */
503 if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor, &q->prng)) {
504 if (skb_is_gso(skb)) {
505 skb = netem_segment(skb, sch, to_free);
506 if (!skb)
507 return rc_drop;
508 segs = skb->next;
509 skb_mark_not_on_list(skb);
510 qdisc_skb_cb(skb)->pkt_len = skb->len;
511 }
512
513 skb = skb_unshare(skb, GFP_ATOMIC);
514 if (unlikely(!skb)) {
515 qdisc_qstats_drop(sch);
516 goto finish_segs;
517 }
518 if (skb->ip_summed == CHECKSUM_PARTIAL &&
519 skb_checksum_help(skb)) {
520 qdisc_drop(skb, sch, to_free);
521 skb = NULL;
522 goto finish_segs;
523 }
524
525 skb->data[get_random_u32_below(skb_headlen(skb))] ^=
526 1<<get_random_u32_below(8);
527 }
528
529 if (unlikely(sch->q.qlen >= sch->limit)) {
530 /* re-link segs, so that qdisc_drop_all() frees them all */
531 skb->next = segs;
532 qdisc_drop_all(skb, sch, to_free);
533 return rc_drop;
534 }
535
536 qdisc_qstats_backlog_inc(sch, skb);
537
538 cb = netem_skb_cb(skb);
539 if (q->gap == 0 || /* not doing reordering */
540 q->counter < q->gap - 1 || /* inside last reordering gap */
541 q->reorder < get_crandom(&q->reorder_cor, &q->prng)) {
542 u64 now;
543 s64 delay;
544
545 delay = tabledist(q->latency, q->jitter,
546 &q->delay_cor, &q->prng, q->delay_dist);
547
548 now = ktime_get_ns();
549
550 if (q->rate) {
551 struct netem_skb_cb *last = NULL;
552
553 if (sch->q.tail)
554 last = netem_skb_cb(sch->q.tail);
555 if (q->t_root.rb_node) {
556 struct sk_buff *t_skb;
557 struct netem_skb_cb *t_last;
558
559 t_skb = skb_rb_last(&q->t_root);
560 t_last = netem_skb_cb(t_skb);
561 if (!last ||
562 t_last->time_to_send > last->time_to_send)
563 last = t_last;
564 }
565 if (q->t_tail) {
566 struct netem_skb_cb *t_last =
567 netem_skb_cb(q->t_tail);
568
569 if (!last ||
570 t_last->time_to_send > last->time_to_send)
571 last = t_last;
572 }
573
574 if (last) {
575 /*
576 * Last packet in queue is reference point (now),
577 * calculate this time bonus and subtract
578 * from delay.
579 */
580 delay -= last->time_to_send - now;
581 delay = max_t(s64, 0, delay);
582 now = last->time_to_send;
583 }
584
585 delay += packet_time_ns(qdisc_pkt_len(skb), q);
586 }
587
588 cb->time_to_send = now + delay;
589 ++q->counter;
590 tfifo_enqueue(skb, sch);
591 } else {
592 /*
593 * Do re-ordering by putting one out of N packets at the front
594 * of the queue.
595 */
596 cb->time_to_send = ktime_get_ns();
597 q->counter = 0;
598
599 __qdisc_enqueue_head(skb, &sch->q);
600 sch->qstats.requeues++;
601 }
602
603finish_segs:
604 if (segs) {
605 unsigned int len, last_len;
606 int nb;
607
608 len = skb ? skb->len : 0;
609 nb = skb ? 1 : 0;
610
611 while (segs) {
612 skb2 = segs->next;
613 skb_mark_not_on_list(segs);
614 qdisc_skb_cb(segs)->pkt_len = segs->len;
615 last_len = segs->len;
616 rc = qdisc_enqueue(segs, sch, to_free);
617 if (rc != NET_XMIT_SUCCESS) {
618 if (net_xmit_drop_count(rc))
619 qdisc_qstats_drop(sch);
620 } else {
621 nb++;
622 len += last_len;
623 }
624 segs = skb2;
625 }
626 /* Parent qdiscs accounted for 1 skb of size @prev_len */
627 qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
628 } else if (!skb) {
629 return NET_XMIT_DROP;
630 }
631 return NET_XMIT_SUCCESS;
632}
633
634/* Delay the next round with a new future slot with a
635 * correct number of bytes and packets.
636 */
637
638static void get_slot_next(struct netem_sched_data *q, u64 now)
639{
640 s64 next_delay;
641
642 if (!q->slot_dist)
643 next_delay = q->slot_config.min_delay +
644 (get_random_u32() *
645 (q->slot_config.max_delay -
646 q->slot_config.min_delay) >> 32);
647 else
648 next_delay = tabledist(q->slot_config.dist_delay,
649 (s32)(q->slot_config.dist_jitter),
650 NULL, &q->prng, q->slot_dist);
651
652 q->slot.slot_next = now + next_delay;
653 q->slot.packets_left = q->slot_config.max_packets;
654 q->slot.bytes_left = q->slot_config.max_bytes;
655}
656
657static struct sk_buff *netem_peek(struct netem_sched_data *q)
658{
659 struct sk_buff *skb = skb_rb_first(&q->t_root);
660 u64 t1, t2;
661
662 if (!skb)
663 return q->t_head;
664 if (!q->t_head)
665 return skb;
666
667 t1 = netem_skb_cb(skb)->time_to_send;
668 t2 = netem_skb_cb(q->t_head)->time_to_send;
669 if (t1 < t2)
670 return skb;
671 return q->t_head;
672}
673
674static void netem_erase_head(struct netem_sched_data *q, struct sk_buff *skb)
675{
676 if (skb == q->t_head) {
677 q->t_head = skb->next;
678 if (!q->t_head)
679 q->t_tail = NULL;
680 } else {
681 rb_erase(&skb->rbnode, &q->t_root);
682 }
683}
684
685static struct sk_buff *netem_dequeue(struct Qdisc *sch)
686{
687 struct netem_sched_data *q = qdisc_priv(sch);
688 struct sk_buff *skb;
689
690tfifo_dequeue:
691 skb = __qdisc_dequeue_head(&sch->q);
692 if (skb) {
693 qdisc_qstats_backlog_dec(sch, skb);
694deliver:
695 qdisc_bstats_update(sch, skb);
696 return skb;
697 }
698 skb = netem_peek(q);
699 if (skb) {
700 u64 time_to_send;
701 u64 now = ktime_get_ns();
702
703 /* if more time remaining? */
704 time_to_send = netem_skb_cb(skb)->time_to_send;
705 if (q->slot.slot_next && q->slot.slot_next < time_to_send)
706 get_slot_next(q, now);
707
708 if (time_to_send <= now && q->slot.slot_next <= now) {
709 netem_erase_head(q, skb);
710 sch->q.qlen--;
711 qdisc_qstats_backlog_dec(sch, skb);
712 skb->next = NULL;
713 skb->prev = NULL;
714 /* skb->dev shares skb->rbnode area,
715 * we need to restore its value.
716 */
717 skb->dev = qdisc_dev(sch);
718
719 if (q->slot.slot_next) {
720 q->slot.packets_left--;
721 q->slot.bytes_left -= qdisc_pkt_len(skb);
722 if (q->slot.packets_left <= 0 ||
723 q->slot.bytes_left <= 0)
724 get_slot_next(q, now);
725 }
726
727 if (q->qdisc) {
728 unsigned int pkt_len = qdisc_pkt_len(skb);
729 struct sk_buff *to_free = NULL;
730 int err;
731
732 err = qdisc_enqueue(skb, q->qdisc, &to_free);
733 kfree_skb_list(to_free);
734 if (err != NET_XMIT_SUCCESS &&
735 net_xmit_drop_count(err)) {
736 qdisc_qstats_drop(sch);
737 qdisc_tree_reduce_backlog(sch, 1,
738 pkt_len);
739 }
740 goto tfifo_dequeue;
741 }
742 goto deliver;
743 }
744
745 if (q->qdisc) {
746 skb = q->qdisc->ops->dequeue(q->qdisc);
747 if (skb)
748 goto deliver;
749 }
750
751 qdisc_watchdog_schedule_ns(&q->watchdog,
752 max(time_to_send,
753 q->slot.slot_next));
754 }
755
756 if (q->qdisc) {
757 skb = q->qdisc->ops->dequeue(q->qdisc);
758 if (skb)
759 goto deliver;
760 }
761 return NULL;
762}
763
764static void netem_reset(struct Qdisc *sch)
765{
766 struct netem_sched_data *q = qdisc_priv(sch);
767
768 qdisc_reset_queue(sch);
769 tfifo_reset(sch);
770 if (q->qdisc)
771 qdisc_reset(q->qdisc);
772 qdisc_watchdog_cancel(&q->watchdog);
773}
774
775static void dist_free(struct disttable *d)
776{
777 kvfree(d);
778}
779
780/*
781 * Distribution data is a variable size payload containing
782 * signed 16 bit values.
783 */
784
785static int get_dist_table(struct disttable **tbl, const struct nlattr *attr)
786{
787 size_t n = nla_len(attr)/sizeof(__s16);
788 const __s16 *data = nla_data(attr);
789 struct disttable *d;
790 int i;
791
792 if (!n || n > NETEM_DIST_MAX)
793 return -EINVAL;
794
795 d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
796 if (!d)
797 return -ENOMEM;
798
799 d->size = n;
800 for (i = 0; i < n; i++)
801 d->table[i] = data[i];
802
803 *tbl = d;
804 return 0;
805}
806
807static void get_slot(struct netem_sched_data *q, const struct nlattr *attr)
808{
809 const struct tc_netem_slot *c = nla_data(attr);
810
811 q->slot_config = *c;
812 if (q->slot_config.max_packets == 0)
813 q->slot_config.max_packets = INT_MAX;
814 if (q->slot_config.max_bytes == 0)
815 q->slot_config.max_bytes = INT_MAX;
816
817 /* capping dist_jitter to the range acceptable by tabledist() */
818 q->slot_config.dist_jitter = min_t(__s64, INT_MAX, abs(q->slot_config.dist_jitter));
819
820 q->slot.packets_left = q->slot_config.max_packets;
821 q->slot.bytes_left = q->slot_config.max_bytes;
822 if (q->slot_config.min_delay | q->slot_config.max_delay |
823 q->slot_config.dist_jitter)
824 q->slot.slot_next = ktime_get_ns();
825 else
826 q->slot.slot_next = 0;
827}
828
829static void get_correlation(struct netem_sched_data *q, const struct nlattr *attr)
830{
831 const struct tc_netem_corr *c = nla_data(attr);
832
833 init_crandom(&q->delay_cor, c->delay_corr);
834 init_crandom(&q->loss_cor, c->loss_corr);
835 init_crandom(&q->dup_cor, c->dup_corr);
836}
837
838static void get_reorder(struct netem_sched_data *q, const struct nlattr *attr)
839{
840 const struct tc_netem_reorder *r = nla_data(attr);
841
842 q->reorder = r->probability;
843 init_crandom(&q->reorder_cor, r->correlation);
844}
845
846static void get_corrupt(struct netem_sched_data *q, const struct nlattr *attr)
847{
848 const struct tc_netem_corrupt *r = nla_data(attr);
849
850 q->corrupt = r->probability;
851 init_crandom(&q->corrupt_cor, r->correlation);
852}
853
854static void get_rate(struct netem_sched_data *q, const struct nlattr *attr)
855{
856 const struct tc_netem_rate *r = nla_data(attr);
857
858 q->rate = r->rate;
859 q->packet_overhead = r->packet_overhead;
860 q->cell_size = r->cell_size;
861 q->cell_overhead = r->cell_overhead;
862 if (q->cell_size)
863 q->cell_size_reciprocal = reciprocal_value(q->cell_size);
864 else
865 q->cell_size_reciprocal = (struct reciprocal_value) { 0 };
866}
867
868static int get_loss_clg(struct netem_sched_data *q, const struct nlattr *attr)
869{
870 const struct nlattr *la;
871 int rem;
872
873 nla_for_each_nested(la, attr, rem) {
874 u16 type = nla_type(la);
875
876 switch (type) {
877 case NETEM_LOSS_GI: {
878 const struct tc_netem_gimodel *gi = nla_data(la);
879
880 if (nla_len(la) < sizeof(struct tc_netem_gimodel)) {
881 pr_info("netem: incorrect gi model size\n");
882 return -EINVAL;
883 }
884
885 q->loss_model = CLG_4_STATES;
886
887 q->clg.state = TX_IN_GAP_PERIOD;
888 q->clg.a1 = gi->p13;
889 q->clg.a2 = gi->p31;
890 q->clg.a3 = gi->p32;
891 q->clg.a4 = gi->p14;
892 q->clg.a5 = gi->p23;
893 break;
894 }
895
896 case NETEM_LOSS_GE: {
897 const struct tc_netem_gemodel *ge = nla_data(la);
898
899 if (nla_len(la) < sizeof(struct tc_netem_gemodel)) {
900 pr_info("netem: incorrect ge model size\n");
901 return -EINVAL;
902 }
903
904 q->loss_model = CLG_GILB_ELL;
905 q->clg.state = GOOD_STATE;
906 q->clg.a1 = ge->p;
907 q->clg.a2 = ge->r;
908 q->clg.a3 = ge->h;
909 q->clg.a4 = ge->k1;
910 break;
911 }
912
913 default:
914 pr_info("netem: unknown loss type %u\n", type);
915 return -EINVAL;
916 }
917 }
918
919 return 0;
920}
921
922static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
923 [TCA_NETEM_CORR] = { .len = sizeof(struct tc_netem_corr) },
924 [TCA_NETEM_REORDER] = { .len = sizeof(struct tc_netem_reorder) },
925 [TCA_NETEM_CORRUPT] = { .len = sizeof(struct tc_netem_corrupt) },
926 [TCA_NETEM_RATE] = { .len = sizeof(struct tc_netem_rate) },
927 [TCA_NETEM_LOSS] = { .type = NLA_NESTED },
928 [TCA_NETEM_ECN] = { .type = NLA_U32 },
929 [TCA_NETEM_RATE64] = { .type = NLA_U64 },
930 [TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
931 [TCA_NETEM_JITTER64] = { .type = NLA_S64 },
932 [TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
933 [TCA_NETEM_PRNG_SEED] = { .type = NLA_U64 },
934};
935
936static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
937 const struct nla_policy *policy, int len)
938{
939 int nested_len = nla_len(nla) - NLA_ALIGN(len);
940
941 if (nested_len < 0) {
942 pr_info("netem: invalid attributes len %d\n", nested_len);
943 return -EINVAL;
944 }
945
946 if (nested_len >= nla_attr_size(0))
947 return nla_parse_deprecated(tb, maxtype,
948 nla_data(nla) + NLA_ALIGN(len),
949 nested_len, policy, NULL);
950
951 memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
952 return 0;
953}
954
955/* Parse netlink message to set options */
956static int netem_change(struct Qdisc *sch, struct nlattr *opt,
957 struct netlink_ext_ack *extack)
958{
959 struct netem_sched_data *q = qdisc_priv(sch);
960 struct nlattr *tb[TCA_NETEM_MAX + 1];
961 struct disttable *delay_dist = NULL;
962 struct disttable *slot_dist = NULL;
963 struct tc_netem_qopt *qopt;
964 struct clgstate old_clg;
965 int old_loss_model = CLG_RANDOM;
966 int ret;
967
968 qopt = nla_data(opt);
969 ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
970 if (ret < 0)
971 return ret;
972
973 if (tb[TCA_NETEM_DELAY_DIST]) {
974 ret = get_dist_table(&delay_dist, tb[TCA_NETEM_DELAY_DIST]);
975 if (ret)
976 goto table_free;
977 }
978
979 if (tb[TCA_NETEM_SLOT_DIST]) {
980 ret = get_dist_table(&slot_dist, tb[TCA_NETEM_SLOT_DIST]);
981 if (ret)
982 goto table_free;
983 }
984
985 sch_tree_lock(sch);
986 /* backup q->clg and q->loss_model */
987 old_clg = q->clg;
988 old_loss_model = q->loss_model;
989
990 if (tb[TCA_NETEM_LOSS]) {
991 ret = get_loss_clg(q, tb[TCA_NETEM_LOSS]);
992 if (ret) {
993 q->loss_model = old_loss_model;
994 q->clg = old_clg;
995 goto unlock;
996 }
997 } else {
998 q->loss_model = CLG_RANDOM;
999 }
1000
1001 if (delay_dist)
1002 swap(q->delay_dist, delay_dist);
1003 if (slot_dist)
1004 swap(q->slot_dist, slot_dist);
1005 sch->limit = qopt->limit;
1006
1007 q->latency = PSCHED_TICKS2NS(qopt->latency);
1008 q->jitter = PSCHED_TICKS2NS(qopt->jitter);
1009 q->limit = qopt->limit;
1010 q->gap = qopt->gap;
1011 q->counter = 0;
1012 q->loss = qopt->loss;
1013 q->duplicate = qopt->duplicate;
1014
1015 /* for compatibility with earlier versions.
1016 * if gap is set, need to assume 100% probability
1017 */
1018 if (q->gap)
1019 q->reorder = ~0;
1020
1021 if (tb[TCA_NETEM_CORR])
1022 get_correlation(q, tb[TCA_NETEM_CORR]);
1023
1024 if (tb[TCA_NETEM_REORDER])
1025 get_reorder(q, tb[TCA_NETEM_REORDER]);
1026
1027 if (tb[TCA_NETEM_CORRUPT])
1028 get_corrupt(q, tb[TCA_NETEM_CORRUPT]);
1029
1030 if (tb[TCA_NETEM_RATE])
1031 get_rate(q, tb[TCA_NETEM_RATE]);
1032
1033 if (tb[TCA_NETEM_RATE64])
1034 q->rate = max_t(u64, q->rate,
1035 nla_get_u64(tb[TCA_NETEM_RATE64]));
1036
1037 if (tb[TCA_NETEM_LATENCY64])
1038 q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
1039
1040 if (tb[TCA_NETEM_JITTER64])
1041 q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
1042
1043 if (tb[TCA_NETEM_ECN])
1044 q->ecn = nla_get_u32(tb[TCA_NETEM_ECN]);
1045
1046 if (tb[TCA_NETEM_SLOT])
1047 get_slot(q, tb[TCA_NETEM_SLOT]);
1048
1049 /* capping jitter to the range acceptable by tabledist() */
1050 q->jitter = min_t(s64, abs(q->jitter), INT_MAX);
1051
1052 if (tb[TCA_NETEM_PRNG_SEED])
1053 q->prng.seed = nla_get_u64(tb[TCA_NETEM_PRNG_SEED]);
1054 else
1055 q->prng.seed = get_random_u64();
1056 prandom_seed_state(&q->prng.prng_state, q->prng.seed);
1057
1058unlock:
1059 sch_tree_unlock(sch);
1060
1061table_free:
1062 dist_free(delay_dist);
1063 dist_free(slot_dist);
1064 return ret;
1065}
1066
1067static int netem_init(struct Qdisc *sch, struct nlattr *opt,
1068 struct netlink_ext_ack *extack)
1069{
1070 struct netem_sched_data *q = qdisc_priv(sch);
1071 int ret;
1072
1073 qdisc_watchdog_init(&q->watchdog, sch);
1074
1075 if (!opt)
1076 return -EINVAL;
1077
1078 q->loss_model = CLG_RANDOM;
1079 ret = netem_change(sch, opt, extack);
1080 if (ret)
1081 pr_info("netem: change failed\n");
1082 return ret;
1083}
1084
1085static void netem_destroy(struct Qdisc *sch)
1086{
1087 struct netem_sched_data *q = qdisc_priv(sch);
1088
1089 qdisc_watchdog_cancel(&q->watchdog);
1090 if (q->qdisc)
1091 qdisc_put(q->qdisc);
1092 dist_free(q->delay_dist);
1093 dist_free(q->slot_dist);
1094}
1095
1096static int dump_loss_model(const struct netem_sched_data *q,
1097 struct sk_buff *skb)
1098{
1099 struct nlattr *nest;
1100
1101 nest = nla_nest_start_noflag(skb, TCA_NETEM_LOSS);
1102 if (nest == NULL)
1103 goto nla_put_failure;
1104
1105 switch (q->loss_model) {
1106 case CLG_RANDOM:
1107 /* legacy loss model */
1108 nla_nest_cancel(skb, nest);
1109 return 0; /* no data */
1110
1111 case CLG_4_STATES: {
1112 struct tc_netem_gimodel gi = {
1113 .p13 = q->clg.a1,
1114 .p31 = q->clg.a2,
1115 .p32 = q->clg.a3,
1116 .p14 = q->clg.a4,
1117 .p23 = q->clg.a5,
1118 };
1119
1120 if (nla_put(skb, NETEM_LOSS_GI, sizeof(gi), &gi))
1121 goto nla_put_failure;
1122 break;
1123 }
1124 case CLG_GILB_ELL: {
1125 struct tc_netem_gemodel ge = {
1126 .p = q->clg.a1,
1127 .r = q->clg.a2,
1128 .h = q->clg.a3,
1129 .k1 = q->clg.a4,
1130 };
1131
1132 if (nla_put(skb, NETEM_LOSS_GE, sizeof(ge), &ge))
1133 goto nla_put_failure;
1134 break;
1135 }
1136 }
1137
1138 nla_nest_end(skb, nest);
1139 return 0;
1140
1141nla_put_failure:
1142 nla_nest_cancel(skb, nest);
1143 return -1;
1144}
1145
1146static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
1147{
1148 const struct netem_sched_data *q = qdisc_priv(sch);
1149 struct nlattr *nla = (struct nlattr *) skb_tail_pointer(skb);
1150 struct tc_netem_qopt qopt;
1151 struct tc_netem_corr cor;
1152 struct tc_netem_reorder reorder;
1153 struct tc_netem_corrupt corrupt;
1154 struct tc_netem_rate rate;
1155 struct tc_netem_slot slot;
1156
1157 qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency),
1158 UINT_MAX);
1159 qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter),
1160 UINT_MAX);
1161 qopt.limit = q->limit;
1162 qopt.loss = q->loss;
1163 qopt.gap = q->gap;
1164 qopt.duplicate = q->duplicate;
1165 if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt))
1166 goto nla_put_failure;
1167
1168 if (nla_put(skb, TCA_NETEM_LATENCY64, sizeof(q->latency), &q->latency))
1169 goto nla_put_failure;
1170
1171 if (nla_put(skb, TCA_NETEM_JITTER64, sizeof(q->jitter), &q->jitter))
1172 goto nla_put_failure;
1173
1174 cor.delay_corr = q->delay_cor.rho;
1175 cor.loss_corr = q->loss_cor.rho;
1176 cor.dup_corr = q->dup_cor.rho;
1177 if (nla_put(skb, TCA_NETEM_CORR, sizeof(cor), &cor))
1178 goto nla_put_failure;
1179
1180 reorder.probability = q->reorder;
1181 reorder.correlation = q->reorder_cor.rho;
1182 if (nla_put(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder))
1183 goto nla_put_failure;
1184
1185 corrupt.probability = q->corrupt;
1186 corrupt.correlation = q->corrupt_cor.rho;
1187 if (nla_put(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt))
1188 goto nla_put_failure;
1189
1190 if (q->rate >= (1ULL << 32)) {
1191 if (nla_put_u64_64bit(skb, TCA_NETEM_RATE64, q->rate,
1192 TCA_NETEM_PAD))
1193 goto nla_put_failure;
1194 rate.rate = ~0U;
1195 } else {
1196 rate.rate = q->rate;
1197 }
1198 rate.packet_overhead = q->packet_overhead;
1199 rate.cell_size = q->cell_size;
1200 rate.cell_overhead = q->cell_overhead;
1201 if (nla_put(skb, TCA_NETEM_RATE, sizeof(rate), &rate))
1202 goto nla_put_failure;
1203
1204 if (q->ecn && nla_put_u32(skb, TCA_NETEM_ECN, q->ecn))
1205 goto nla_put_failure;
1206
1207 if (dump_loss_model(q, skb) != 0)
1208 goto nla_put_failure;
1209
1210 if (q->slot_config.min_delay | q->slot_config.max_delay |
1211 q->slot_config.dist_jitter) {
1212 slot = q->slot_config;
1213 if (slot.max_packets == INT_MAX)
1214 slot.max_packets = 0;
1215 if (slot.max_bytes == INT_MAX)
1216 slot.max_bytes = 0;
1217 if (nla_put(skb, TCA_NETEM_SLOT, sizeof(slot), &slot))
1218 goto nla_put_failure;
1219 }
1220
1221 if (nla_put_u64_64bit(skb, TCA_NETEM_PRNG_SEED, q->prng.seed,
1222 TCA_NETEM_PAD))
1223 goto nla_put_failure;
1224
1225 return nla_nest_end(skb, nla);
1226
1227nla_put_failure:
1228 nlmsg_trim(skb, nla);
1229 return -1;
1230}
1231
1232static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
1233 struct sk_buff *skb, struct tcmsg *tcm)
1234{
1235 struct netem_sched_data *q = qdisc_priv(sch);
1236
1237 if (cl != 1 || !q->qdisc) /* only one class */
1238 return -ENOENT;
1239
1240 tcm->tcm_handle |= TC_H_MIN(1);
1241 tcm->tcm_info = q->qdisc->handle;
1242
1243 return 0;
1244}
1245
1246static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
1247 struct Qdisc **old, struct netlink_ext_ack *extack)
1248{
1249 struct netem_sched_data *q = qdisc_priv(sch);
1250
1251 *old = qdisc_replace(sch, new, &q->qdisc);
1252 return 0;
1253}
1254
1255static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
1256{
1257 struct netem_sched_data *q = qdisc_priv(sch);
1258 return q->qdisc;
1259}
1260
1261static unsigned long netem_find(struct Qdisc *sch, u32 classid)
1262{
1263 return 1;
1264}
1265
1266static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
1267{
1268 if (!walker->stop) {
1269 if (!tc_qdisc_stats_dump(sch, 1, walker))
1270 return;
1271 }
1272}
1273
1274static const struct Qdisc_class_ops netem_class_ops = {
1275 .graft = netem_graft,
1276 .leaf = netem_leaf,
1277 .find = netem_find,
1278 .walk = netem_walk,
1279 .dump = netem_dump_class,
1280};
1281
1282static struct Qdisc_ops netem_qdisc_ops __read_mostly = {
1283 .id = "netem",
1284 .cl_ops = &netem_class_ops,
1285 .priv_size = sizeof(struct netem_sched_data),
1286 .enqueue = netem_enqueue,
1287 .dequeue = netem_dequeue,
1288 .peek = qdisc_peek_dequeued,
1289 .init = netem_init,
1290 .reset = netem_reset,
1291 .destroy = netem_destroy,
1292 .change = netem_change,
1293 .dump = netem_dump,
1294 .owner = THIS_MODULE,
1295};
1296MODULE_ALIAS_NET_SCH("netem");
1297
1298
1299static int __init netem_module_init(void)
1300{
1301 pr_info("netem: version " VERSION "\n");
1302 return register_qdisc(&netem_qdisc_ops);
1303}
1304static void __exit netem_module_exit(void)
1305{
1306 unregister_qdisc(&netem_qdisc_ops);
1307}
1308module_init(netem_module_init)
1309module_exit(netem_module_exit)
1310MODULE_LICENSE("GPL");
1311MODULE_DESCRIPTION("Network characteristics emulator qdisc");