1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * taskstats.c - Export per-task statistics to userland
4 *
5 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
6 * (C) Balbir Singh, IBM Corp. 2006
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/taskstats_kern.h>
11 #include <linux/tsacct_kern.h>
12 #include <linux/delayacct.h>
13 #include <linux/cpumask.h>
14 #include <linux/percpu.h>
15 #include <linux/slab.h>
16 #include <linux/cgroupstats.h>
17 #include <linux/cgroup.h>
18 #include <linux/fs.h>
19 #include <linux/file.h>
20 #include <linux/pid_namespace.h>
21 #include <net/genetlink.h>
22 #include <linux/atomic.h>
23 #include <linux/sched/cputime.h>
24
25 /*
26 * Maximum length of a cpumask that can be specified in
27 * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
28 */
29 #define TASKSTATS_CPUMASK_MAXLEN (100+6*NR_CPUS)
30
31 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
32 static int family_registered;
33 struct kmem_cache *taskstats_cache;
34
35 static struct genl_family family;
36
37 static const struct nla_policy taskstats_cmd_get_policy[] = {
38 [TASKSTATS_CMD_ATTR_PID] = { .type = NLA_U32 },
39 [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
40 [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
41 [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
42
43 static const struct nla_policy cgroupstats_cmd_get_policy[] = {
44 [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
45 };
46
47 struct listener {
48 struct list_head list;
49 pid_t pid;
50 char valid;
51 };
52
53 struct listener_list {
54 struct rw_semaphore sem;
55 struct list_head list;
56 };
57 static DEFINE_PER_CPU(struct listener_list, listener_array);
58
59 enum actions {
60 REGISTER,
61 DEREGISTER,
62 CPU_DONT_CARE
63 };
64
prepare_reply(struct genl_info * info,u8 cmd,struct sk_buff ** skbp,size_t size)65 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
66 size_t size)
67 {
68 struct sk_buff *skb;
69 void *reply;
70
71 /*
72 * If new attributes are added, please revisit this allocation
73 */
74 skb = genlmsg_new(size, GFP_KERNEL);
75 if (!skb)
76 return -ENOMEM;
77
78 if (!info) {
79 int seq = this_cpu_inc_return(taskstats_seqnum) - 1;
80
81 reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
82 } else
83 reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
84 if (reply == NULL) {
85 nlmsg_free(skb);
86 return -EINVAL;
87 }
88
89 *skbp = skb;
90 return 0;
91 }
92
93 /*
94 * Send taskstats data in @skb to listener with nl_pid @pid
95 */
send_reply(struct sk_buff * skb,struct genl_info * info)96 static int send_reply(struct sk_buff *skb, struct genl_info *info)
97 {
98 struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
99 void *reply = genlmsg_data(genlhdr);
100
101 genlmsg_end(skb, reply);
102
103 return genlmsg_reply(skb, info);
104 }
105
106 /*
107 * Send taskstats data in @skb to listeners registered for @cpu's exit data
108 */
send_cpu_listeners(struct sk_buff * skb,struct listener_list * listeners)109 static void send_cpu_listeners(struct sk_buff *skb,
110 struct listener_list *listeners)
111 {
112 struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
113 struct listener *s, *tmp;
114 struct sk_buff *skb_next, *skb_cur = skb;
115 void *reply = genlmsg_data(genlhdr);
116 int rc, delcount = 0;
117
118 genlmsg_end(skb, reply);
119
120 rc = 0;
121 down_read(&listeners->sem);
122 list_for_each_entry(s, &listeners->list, list) {
123 skb_next = NULL;
124 if (!list_is_last(&s->list, &listeners->list)) {
125 skb_next = skb_clone(skb_cur, GFP_KERNEL);
126 if (!skb_next)
127 break;
128 }
129 rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
130 if (rc == -ECONNREFUSED) {
131 s->valid = 0;
132 delcount++;
133 }
134 skb_cur = skb_next;
135 }
136 up_read(&listeners->sem);
137
138 if (skb_cur)
139 nlmsg_free(skb_cur);
140
141 if (!delcount)
142 return;
143
144 /* Delete invalidated entries */
145 down_write(&listeners->sem);
146 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
147 if (!s->valid) {
148 list_del(&s->list);
149 kfree(s);
150 }
151 }
152 up_write(&listeners->sem);
153 }
154
fill_stats(struct user_namespace * user_ns,struct pid_namespace * pid_ns,struct task_struct * tsk,struct taskstats * stats)155 static void fill_stats(struct user_namespace *user_ns,
156 struct pid_namespace *pid_ns,
157 struct task_struct *tsk, struct taskstats *stats)
158 {
159 memset(stats, 0, sizeof(*stats));
160 /*
161 * Each accounting subsystem adds calls to its functions to
162 * fill in relevant parts of struct taskstsats as follows
163 *
164 * per-task-foo(stats, tsk);
165 */
166
167 delayacct_add_tsk(stats, tsk);
168
169 /* fill in basic acct fields */
170 stats->version = TASKSTATS_VERSION;
171 stats->nvcsw = tsk->nvcsw;
172 stats->nivcsw = tsk->nivcsw;
173 bacct_add_tsk(user_ns, pid_ns, stats, tsk);
174
175 /* fill in extended acct fields */
176 xacct_add_tsk(stats, tsk);
177 }
178
fill_stats_for_pid(pid_t pid,struct taskstats * stats)179 static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
180 {
181 struct task_struct *tsk;
182
183 tsk = find_get_task_by_vpid(pid);
184 if (!tsk)
185 return -ESRCH;
186 fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
187 put_task_struct(tsk);
188 return 0;
189 }
190
fill_stats_for_tgid(pid_t tgid,struct taskstats * stats)191 static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
192 {
193 struct task_struct *tsk, *first;
194 unsigned long flags;
195 int rc = -ESRCH;
196 u64 delta, utime, stime;
197 u64 start_time;
198
199 /*
200 * Add additional stats from live tasks except zombie thread group
201 * leaders who are already counted with the dead tasks
202 */
203 rcu_read_lock();
204 first = find_task_by_vpid(tgid);
205
206 if (!first || !lock_task_sighand(first, &flags))
207 goto out;
208
209 if (first->signal->stats)
210 memcpy(stats, first->signal->stats, sizeof(*stats));
211 else
212 memset(stats, 0, sizeof(*stats));
213
214 tsk = first;
215 start_time = ktime_get_ns();
216 do {
217 if (tsk->exit_state)
218 continue;
219 /*
220 * Accounting subsystem can call its functions here to
221 * fill in relevant parts of struct taskstsats as follows
222 *
223 * per-task-foo(stats, tsk);
224 */
225 delayacct_add_tsk(stats, tsk);
226
227 /* calculate task elapsed time in nsec */
228 delta = start_time - tsk->start_time;
229 /* Convert to micro seconds */
230 do_div(delta, NSEC_PER_USEC);
231 stats->ac_etime += delta;
232
233 task_cputime(tsk, &utime, &stime);
234 stats->ac_utime += div_u64(utime, NSEC_PER_USEC);
235 stats->ac_stime += div_u64(stime, NSEC_PER_USEC);
236
237 stats->nvcsw += tsk->nvcsw;
238 stats->nivcsw += tsk->nivcsw;
239 } while_each_thread(first, tsk);
240
241 unlock_task_sighand(first, &flags);
242 rc = 0;
243 out:
244 rcu_read_unlock();
245
246 stats->version = TASKSTATS_VERSION;
247 /*
248 * Accounting subsystems can also add calls here to modify
249 * fields of taskstats.
250 */
251 return rc;
252 }
253
fill_tgid_exit(struct task_struct * tsk)254 static void fill_tgid_exit(struct task_struct *tsk)
255 {
256 unsigned long flags;
257
258 spin_lock_irqsave(&tsk->sighand->siglock, flags);
259 if (!tsk->signal->stats)
260 goto ret;
261
262 /*
263 * Each accounting subsystem calls its functions here to
264 * accumalate its per-task stats for tsk, into the per-tgid structure
265 *
266 * per-task-foo(tsk->signal->stats, tsk);
267 */
268 delayacct_add_tsk(tsk->signal->stats, tsk);
269 ret:
270 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
271 return;
272 }
273
add_del_listener(pid_t pid,const struct cpumask * mask,int isadd)274 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
275 {
276 struct listener_list *listeners;
277 struct listener *s, *tmp, *s2;
278 unsigned int cpu;
279 int ret = 0;
280
281 if (!cpumask_subset(mask, cpu_possible_mask))
282 return -EINVAL;
283
284 if (current_user_ns() != &init_user_ns)
285 return -EINVAL;
286
287 if (task_active_pid_ns(current) != &init_pid_ns)
288 return -EINVAL;
289
290 if (isadd == REGISTER) {
291 for_each_cpu(cpu, mask) {
292 s = kmalloc_node(sizeof(struct listener),
293 GFP_KERNEL, cpu_to_node(cpu));
294 if (!s) {
295 ret = -ENOMEM;
296 goto cleanup;
297 }
298 s->pid = pid;
299 s->valid = 1;
300
301 listeners = &per_cpu(listener_array, cpu);
302 down_write(&listeners->sem);
303 list_for_each_entry(s2, &listeners->list, list) {
304 if (s2->pid == pid && s2->valid)
305 goto exists;
306 }
307 list_add(&s->list, &listeners->list);
308 s = NULL;
309 exists:
310 up_write(&listeners->sem);
311 kfree(s); /* nop if NULL */
312 }
313 return 0;
314 }
315
316 /* Deregister or cleanup */
317 cleanup:
318 for_each_cpu(cpu, mask) {
319 listeners = &per_cpu(listener_array, cpu);
320 down_write(&listeners->sem);
321 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
322 if (s->pid == pid) {
323 list_del(&s->list);
324 kfree(s);
325 break;
326 }
327 }
328 up_write(&listeners->sem);
329 }
330 return ret;
331 }
332
parse(struct nlattr * na,struct cpumask * mask)333 static int parse(struct nlattr *na, struct cpumask *mask)
334 {
335 char *data;
336 int len;
337 int ret;
338
339 if (na == NULL)
340 return 1;
341 len = nla_len(na);
342 if (len > TASKSTATS_CPUMASK_MAXLEN)
343 return -E2BIG;
344 if (len < 1)
345 return -EINVAL;
346 data = kmalloc(len, GFP_KERNEL);
347 if (!data)
348 return -ENOMEM;
349 nla_strscpy(data, na, len);
350 ret = cpulist_parse(data, mask);
351 kfree(data);
352 return ret;
353 }
354
mk_reply(struct sk_buff * skb,int type,u32 pid)355 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
356 {
357 struct nlattr *na, *ret;
358 int aggr;
359
360 aggr = (type == TASKSTATS_TYPE_PID)
361 ? TASKSTATS_TYPE_AGGR_PID
362 : TASKSTATS_TYPE_AGGR_TGID;
363
364 na = nla_nest_start_noflag(skb, aggr);
365 if (!na)
366 goto err;
367
368 if (nla_put(skb, type, sizeof(pid), &pid) < 0) {
369 nla_nest_cancel(skb, na);
370 goto err;
371 }
372 ret = nla_reserve_64bit(skb, TASKSTATS_TYPE_STATS,
373 sizeof(struct taskstats), TASKSTATS_TYPE_NULL);
374 if (!ret) {
375 nla_nest_cancel(skb, na);
376 goto err;
377 }
378 nla_nest_end(skb, na);
379
380 return nla_data(ret);
381 err:
382 return NULL;
383 }
384
cgroupstats_user_cmd(struct sk_buff * skb,struct genl_info * info)385 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
386 {
387 int rc = 0;
388 struct sk_buff *rep_skb;
389 struct cgroupstats *stats;
390 struct nlattr *na;
391 size_t size;
392 u32 fd;
393 struct fd f;
394
395 na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
396 if (!na)
397 return -EINVAL;
398
399 fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
400 f = fdget(fd);
401 if (!f.file)
402 return 0;
403
404 size = nla_total_size(sizeof(struct cgroupstats));
405
406 rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
407 size);
408 if (rc < 0)
409 goto err;
410
411 na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
412 sizeof(struct cgroupstats));
413 if (na == NULL) {
414 nlmsg_free(rep_skb);
415 rc = -EMSGSIZE;
416 goto err;
417 }
418
419 stats = nla_data(na);
420 memset(stats, 0, sizeof(*stats));
421
422 rc = cgroupstats_build(stats, f.file->f_path.dentry);
423 if (rc < 0) {
424 nlmsg_free(rep_skb);
425 goto err;
426 }
427
428 rc = send_reply(rep_skb, info);
429
430 err:
431 fdput(f);
432 return rc;
433 }
434
cmd_attr_register_cpumask(struct genl_info * info)435 static int cmd_attr_register_cpumask(struct genl_info *info)
436 {
437 cpumask_var_t mask;
438 int rc;
439
440 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
441 return -ENOMEM;
442 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
443 if (rc < 0)
444 goto out;
445 rc = add_del_listener(info->snd_portid, mask, REGISTER);
446 out:
447 free_cpumask_var(mask);
448 return rc;
449 }
450
cmd_attr_deregister_cpumask(struct genl_info * info)451 static int cmd_attr_deregister_cpumask(struct genl_info *info)
452 {
453 cpumask_var_t mask;
454 int rc;
455
456 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
457 return -ENOMEM;
458 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
459 if (rc < 0)
460 goto out;
461 rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
462 out:
463 free_cpumask_var(mask);
464 return rc;
465 }
466
taskstats_packet_size(void)467 static size_t taskstats_packet_size(void)
468 {
469 size_t size;
470
471 size = nla_total_size(sizeof(u32)) +
472 nla_total_size_64bit(sizeof(struct taskstats)) +
473 nla_total_size(0);
474
475 return size;
476 }
477
cmd_attr_pid(struct genl_info * info)478 static int cmd_attr_pid(struct genl_info *info)
479 {
480 struct taskstats *stats;
481 struct sk_buff *rep_skb;
482 size_t size;
483 u32 pid;
484 int rc;
485
486 size = taskstats_packet_size();
487
488 rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
489 if (rc < 0)
490 return rc;
491
492 rc = -EINVAL;
493 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
494 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
495 if (!stats)
496 goto err;
497
498 rc = fill_stats_for_pid(pid, stats);
499 if (rc < 0)
500 goto err;
501 return send_reply(rep_skb, info);
502 err:
503 nlmsg_free(rep_skb);
504 return rc;
505 }
506
cmd_attr_tgid(struct genl_info * info)507 static int cmd_attr_tgid(struct genl_info *info)
508 {
509 struct taskstats *stats;
510 struct sk_buff *rep_skb;
511 size_t size;
512 u32 tgid;
513 int rc;
514
515 size = taskstats_packet_size();
516
517 rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
518 if (rc < 0)
519 return rc;
520
521 rc = -EINVAL;
522 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
523 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
524 if (!stats)
525 goto err;
526
527 rc = fill_stats_for_tgid(tgid, stats);
528 if (rc < 0)
529 goto err;
530 return send_reply(rep_skb, info);
531 err:
532 nlmsg_free(rep_skb);
533 return rc;
534 }
535
taskstats_user_cmd(struct sk_buff * skb,struct genl_info * info)536 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
537 {
538 if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
539 return cmd_attr_register_cpumask(info);
540 else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
541 return cmd_attr_deregister_cpumask(info);
542 else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
543 return cmd_attr_pid(info);
544 else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
545 return cmd_attr_tgid(info);
546 else
547 return -EINVAL;
548 }
549
taskstats_tgid_alloc(struct task_struct * tsk)550 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
551 {
552 struct signal_struct *sig = tsk->signal;
553 struct taskstats *stats_new, *stats;
554
555 /* Pairs with smp_store_release() below. */
556 stats = smp_load_acquire(&sig->stats);
557 if (stats || thread_group_empty(tsk))
558 return stats;
559
560 /* No problem if kmem_cache_zalloc() fails */
561 stats_new = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
562
563 spin_lock_irq(&tsk->sighand->siglock);
564 stats = sig->stats;
565 if (!stats) {
566 /*
567 * Pairs with smp_store_release() above and order the
568 * kmem_cache_zalloc().
569 */
570 smp_store_release(&sig->stats, stats_new);
571 stats = stats_new;
572 stats_new = NULL;
573 }
574 spin_unlock_irq(&tsk->sighand->siglock);
575
576 if (stats_new)
577 kmem_cache_free(taskstats_cache, stats_new);
578
579 return stats;
580 }
581
582 /* Send pid data out on exit */
taskstats_exit(struct task_struct * tsk,int group_dead)583 void taskstats_exit(struct task_struct *tsk, int group_dead)
584 {
585 int rc;
586 struct listener_list *listeners;
587 struct taskstats *stats;
588 struct sk_buff *rep_skb;
589 size_t size;
590 int is_thread_group;
591
592 if (!family_registered)
593 return;
594
595 /*
596 * Size includes space for nested attributes
597 */
598 size = taskstats_packet_size();
599
600 is_thread_group = !!taskstats_tgid_alloc(tsk);
601 if (is_thread_group) {
602 /* PID + STATS + TGID + STATS */
603 size = 2 * size;
604 /* fill the tsk->signal->stats structure */
605 fill_tgid_exit(tsk);
606 }
607
608 listeners = raw_cpu_ptr(&listener_array);
609 if (list_empty(&listeners->list))
610 return;
611
612 rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
613 if (rc < 0)
614 return;
615
616 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
617 task_pid_nr_ns(tsk, &init_pid_ns));
618 if (!stats)
619 goto err;
620
621 fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
622
623 /*
624 * Doesn't matter if tsk is the leader or the last group member leaving
625 */
626 if (!is_thread_group || !group_dead)
627 goto send;
628
629 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
630 task_tgid_nr_ns(tsk, &init_pid_ns));
631 if (!stats)
632 goto err;
633
634 memcpy(stats, tsk->signal->stats, sizeof(*stats));
635
636 send:
637 send_cpu_listeners(rep_skb, listeners);
638 return;
639 err:
640 nlmsg_free(rep_skb);
641 }
642
643 static const struct genl_ops taskstats_ops[] = {
644 {
645 .cmd = TASKSTATS_CMD_GET,
646 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
647 .doit = taskstats_user_cmd,
648 .policy = taskstats_cmd_get_policy,
649 .maxattr = ARRAY_SIZE(taskstats_cmd_get_policy) - 1,
650 .flags = GENL_ADMIN_PERM,
651 },
652 {
653 .cmd = CGROUPSTATS_CMD_GET,
654 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
655 .doit = cgroupstats_user_cmd,
656 .policy = cgroupstats_cmd_get_policy,
657 .maxattr = ARRAY_SIZE(cgroupstats_cmd_get_policy) - 1,
658 },
659 };
660
661 static struct genl_family family __ro_after_init = {
662 .name = TASKSTATS_GENL_NAME,
663 .version = TASKSTATS_GENL_VERSION,
664 .module = THIS_MODULE,
665 .ops = taskstats_ops,
666 .n_ops = ARRAY_SIZE(taskstats_ops),
667 };
668
669 /* Needed early in initialization */
taskstats_init_early(void)670 void __init taskstats_init_early(void)
671 {
672 unsigned int i;
673
674 taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
675 for_each_possible_cpu(i) {
676 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
677 init_rwsem(&(per_cpu(listener_array, i).sem));
678 }
679 }
680
taskstats_init(void)681 static int __init taskstats_init(void)
682 {
683 int rc;
684
685 rc = genl_register_family(&family);
686 if (rc)
687 return rc;
688
689 family_registered = 1;
690 pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
691 return 0;
692 }
693
694 /*
695 * late initcall ensures initialization of statistics collection
696 * mechanisms precedes initialization of the taskstats interface
697 */
698 late_initcall(taskstats_init);
699
