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1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2020 Facebook */
3
4#include <linux/init.h>
5#include <linux/namei.h>
6#include <linux/pid_namespace.h>
7#include <linux/fs.h>
8#include <linux/fdtable.h>
9#include <linux/filter.h>
10#include <linux/bpf_mem_alloc.h>
11#include <linux/btf_ids.h>
12#include <linux/mm_types.h>
13#include "mmap_unlock_work.h"
14
15static const char * const iter_task_type_names[] = {
16 "ALL",
17 "TID",
18 "PID",
19};
20
21struct bpf_iter_seq_task_common {
22 struct pid_namespace *ns;
23 enum bpf_iter_task_type type;
24 u32 pid;
25 u32 pid_visiting;
26};
27
28struct bpf_iter_seq_task_info {
29 /* The first field must be struct bpf_iter_seq_task_common.
30 * this is assumed by {init, fini}_seq_pidns() callback functions.
31 */
32 struct bpf_iter_seq_task_common common;
33 u32 tid;
34};
35
36static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_common *common,
37 u32 *tid,
38 bool skip_if_dup_files)
39{
40 struct task_struct *task;
41 struct pid *pid;
42 u32 next_tid;
43
44 if (!*tid) {
45 /* The first time, the iterator calls this function. */
46 pid = find_pid_ns(common->pid, common->ns);
47 task = get_pid_task(pid, PIDTYPE_TGID);
48 if (!task)
49 return NULL;
50
51 *tid = common->pid;
52 common->pid_visiting = common->pid;
53
54 return task;
55 }
56
57 /* If the control returns to user space and comes back to the
58 * kernel again, *tid and common->pid_visiting should be the
59 * same for task_seq_start() to pick up the correct task.
60 */
61 if (*tid == common->pid_visiting) {
62 pid = find_pid_ns(common->pid_visiting, common->ns);
63 task = get_pid_task(pid, PIDTYPE_PID);
64
65 return task;
66 }
67
68 task = find_task_by_pid_ns(common->pid_visiting, common->ns);
69 if (!task)
70 return NULL;
71
72retry:
73 task = __next_thread(task);
74 if (!task)
75 return NULL;
76
77 next_tid = __task_pid_nr_ns(task, PIDTYPE_PID, common->ns);
78 if (!next_tid)
79 goto retry;
80
81 if (skip_if_dup_files && task->files == task->group_leader->files)
82 goto retry;
83
84 *tid = common->pid_visiting = next_tid;
85 get_task_struct(task);
86 return task;
87}
88
89static struct task_struct *task_seq_get_next(struct bpf_iter_seq_task_common *common,
90 u32 *tid,
91 bool skip_if_dup_files)
92{
93 struct task_struct *task = NULL;
94 struct pid *pid;
95
96 if (common->type == BPF_TASK_ITER_TID) {
97 if (*tid && *tid != common->pid)
98 return NULL;
99 rcu_read_lock();
100 pid = find_pid_ns(common->pid, common->ns);
101 if (pid) {
102 task = get_pid_task(pid, PIDTYPE_TGID);
103 *tid = common->pid;
104 }
105 rcu_read_unlock();
106
107 return task;
108 }
109
110 if (common->type == BPF_TASK_ITER_TGID) {
111 rcu_read_lock();
112 task = task_group_seq_get_next(common, tid, skip_if_dup_files);
113 rcu_read_unlock();
114
115 return task;
116 }
117
118 rcu_read_lock();
119retry:
120 pid = find_ge_pid(*tid, common->ns);
121 if (pid) {
122 *tid = pid_nr_ns(pid, common->ns);
123 task = get_pid_task(pid, PIDTYPE_PID);
124 if (!task) {
125 ++*tid;
126 goto retry;
127 } else if (skip_if_dup_files && !thread_group_leader(task) &&
128 task->files == task->group_leader->files) {
129 put_task_struct(task);
130 task = NULL;
131 ++*tid;
132 goto retry;
133 }
134 }
135 rcu_read_unlock();
136
137 return task;
138}
139
140static void *task_seq_start(struct seq_file *seq, loff_t *pos)
141{
142 struct bpf_iter_seq_task_info *info = seq->private;
143 struct task_struct *task;
144
145 task = task_seq_get_next(&info->common, &info->tid, false);
146 if (!task)
147 return NULL;
148
149 if (*pos == 0)
150 ++*pos;
151 return task;
152}
153
154static void *task_seq_next(struct seq_file *seq, void *v, loff_t *pos)
155{
156 struct bpf_iter_seq_task_info *info = seq->private;
157 struct task_struct *task;
158
159 ++*pos;
160 ++info->tid;
161 put_task_struct((struct task_struct *)v);
162 task = task_seq_get_next(&info->common, &info->tid, false);
163 if (!task)
164 return NULL;
165
166 return task;
167}
168
169struct bpf_iter__task {
170 __bpf_md_ptr(struct bpf_iter_meta *, meta);
171 __bpf_md_ptr(struct task_struct *, task);
172};
173
174DEFINE_BPF_ITER_FUNC(task, struct bpf_iter_meta *meta, struct task_struct *task)
175
176static int __task_seq_show(struct seq_file *seq, struct task_struct *task,
177 bool in_stop)
178{
179 struct bpf_iter_meta meta;
180 struct bpf_iter__task ctx;
181 struct bpf_prog *prog;
182
183 meta.seq = seq;
184 prog = bpf_iter_get_info(&meta, in_stop);
185 if (!prog)
186 return 0;
187
188 ctx.meta = &meta;
189 ctx.task = task;
190 return bpf_iter_run_prog(prog, &ctx);
191}
192
193static int task_seq_show(struct seq_file *seq, void *v)
194{
195 return __task_seq_show(seq, v, false);
196}
197
198static void task_seq_stop(struct seq_file *seq, void *v)
199{
200 if (!v)
201 (void)__task_seq_show(seq, v, true);
202 else
203 put_task_struct((struct task_struct *)v);
204}
205
206static int bpf_iter_attach_task(struct bpf_prog *prog,
207 union bpf_iter_link_info *linfo,
208 struct bpf_iter_aux_info *aux)
209{
210 unsigned int flags;
211 struct pid *pid;
212 pid_t tgid;
213
214 if ((!!linfo->task.tid + !!linfo->task.pid + !!linfo->task.pid_fd) > 1)
215 return -EINVAL;
216
217 aux->task.type = BPF_TASK_ITER_ALL;
218 if (linfo->task.tid != 0) {
219 aux->task.type = BPF_TASK_ITER_TID;
220 aux->task.pid = linfo->task.tid;
221 }
222 if (linfo->task.pid != 0) {
223 aux->task.type = BPF_TASK_ITER_TGID;
224 aux->task.pid = linfo->task.pid;
225 }
226 if (linfo->task.pid_fd != 0) {
227 aux->task.type = BPF_TASK_ITER_TGID;
228
229 pid = pidfd_get_pid(linfo->task.pid_fd, &flags);
230 if (IS_ERR(pid))
231 return PTR_ERR(pid);
232
233 tgid = pid_nr_ns(pid, task_active_pid_ns(current));
234 aux->task.pid = tgid;
235 put_pid(pid);
236 }
237
238 return 0;
239}
240
241static const struct seq_operations task_seq_ops = {
242 .start = task_seq_start,
243 .next = task_seq_next,
244 .stop = task_seq_stop,
245 .show = task_seq_show,
246};
247
248struct bpf_iter_seq_task_file_info {
249 /* The first field must be struct bpf_iter_seq_task_common.
250 * this is assumed by {init, fini}_seq_pidns() callback functions.
251 */
252 struct bpf_iter_seq_task_common common;
253 struct task_struct *task;
254 u32 tid;
255 u32 fd;
256};
257
258static struct file *
259task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
260{
261 u32 saved_tid = info->tid;
262 struct task_struct *curr_task;
263 unsigned int curr_fd = info->fd;
264
265 /* If this function returns a non-NULL file object,
266 * it held a reference to the task/file.
267 * Otherwise, it does not hold any reference.
268 */
269again:
270 if (info->task) {
271 curr_task = info->task;
272 curr_fd = info->fd;
273 } else {
274 curr_task = task_seq_get_next(&info->common, &info->tid, true);
275 if (!curr_task) {
276 info->task = NULL;
277 return NULL;
278 }
279
280 /* set info->task */
281 info->task = curr_task;
282 if (saved_tid == info->tid)
283 curr_fd = info->fd;
284 else
285 curr_fd = 0;
286 }
287
288 rcu_read_lock();
289 for (;; curr_fd++) {
290 struct file *f;
291 f = task_lookup_next_fdget_rcu(curr_task, &curr_fd);
292 if (!f)
293 break;
294
295 /* set info->fd */
296 info->fd = curr_fd;
297 rcu_read_unlock();
298 return f;
299 }
300
301 /* the current task is done, go to the next task */
302 rcu_read_unlock();
303 put_task_struct(curr_task);
304
305 if (info->common.type == BPF_TASK_ITER_TID) {
306 info->task = NULL;
307 return NULL;
308 }
309
310 info->task = NULL;
311 info->fd = 0;
312 saved_tid = ++(info->tid);
313 goto again;
314}
315
316static void *task_file_seq_start(struct seq_file *seq, loff_t *pos)
317{
318 struct bpf_iter_seq_task_file_info *info = seq->private;
319 struct file *file;
320
321 info->task = NULL;
322 file = task_file_seq_get_next(info);
323 if (file && *pos == 0)
324 ++*pos;
325
326 return file;
327}
328
329static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos)
330{
331 struct bpf_iter_seq_task_file_info *info = seq->private;
332
333 ++*pos;
334 ++info->fd;
335 fput((struct file *)v);
336 return task_file_seq_get_next(info);
337}
338
339struct bpf_iter__task_file {
340 __bpf_md_ptr(struct bpf_iter_meta *, meta);
341 __bpf_md_ptr(struct task_struct *, task);
342 u32 fd __aligned(8);
343 __bpf_md_ptr(struct file *, file);
344};
345
346DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta,
347 struct task_struct *task, u32 fd,
348 struct file *file)
349
350static int __task_file_seq_show(struct seq_file *seq, struct file *file,
351 bool in_stop)
352{
353 struct bpf_iter_seq_task_file_info *info = seq->private;
354 struct bpf_iter__task_file ctx;
355 struct bpf_iter_meta meta;
356 struct bpf_prog *prog;
357
358 meta.seq = seq;
359 prog = bpf_iter_get_info(&meta, in_stop);
360 if (!prog)
361 return 0;
362
363 ctx.meta = &meta;
364 ctx.task = info->task;
365 ctx.fd = info->fd;
366 ctx.file = file;
367 return bpf_iter_run_prog(prog, &ctx);
368}
369
370static int task_file_seq_show(struct seq_file *seq, void *v)
371{
372 return __task_file_seq_show(seq, v, false);
373}
374
375static void task_file_seq_stop(struct seq_file *seq, void *v)
376{
377 struct bpf_iter_seq_task_file_info *info = seq->private;
378
379 if (!v) {
380 (void)__task_file_seq_show(seq, v, true);
381 } else {
382 fput((struct file *)v);
383 put_task_struct(info->task);
384 info->task = NULL;
385 }
386}
387
388static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux)
389{
390 struct bpf_iter_seq_task_common *common = priv_data;
391
392 common->ns = get_pid_ns(task_active_pid_ns(current));
393 common->type = aux->task.type;
394 common->pid = aux->task.pid;
395
396 return 0;
397}
398
399static void fini_seq_pidns(void *priv_data)
400{
401 struct bpf_iter_seq_task_common *common = priv_data;
402
403 put_pid_ns(common->ns);
404}
405
406static const struct seq_operations task_file_seq_ops = {
407 .start = task_file_seq_start,
408 .next = task_file_seq_next,
409 .stop = task_file_seq_stop,
410 .show = task_file_seq_show,
411};
412
413struct bpf_iter_seq_task_vma_info {
414 /* The first field must be struct bpf_iter_seq_task_common.
415 * this is assumed by {init, fini}_seq_pidns() callback functions.
416 */
417 struct bpf_iter_seq_task_common common;
418 struct task_struct *task;
419 struct mm_struct *mm;
420 struct vm_area_struct *vma;
421 u32 tid;
422 unsigned long prev_vm_start;
423 unsigned long prev_vm_end;
424};
425
426enum bpf_task_vma_iter_find_op {
427 task_vma_iter_first_vma, /* use find_vma() with addr 0 */
428 task_vma_iter_next_vma, /* use vma_next() with curr_vma */
429 task_vma_iter_find_vma, /* use find_vma() to find next vma */
430};
431
432static struct vm_area_struct *
433task_vma_seq_get_next(struct bpf_iter_seq_task_vma_info *info)
434{
435 enum bpf_task_vma_iter_find_op op;
436 struct vm_area_struct *curr_vma;
437 struct task_struct *curr_task;
438 struct mm_struct *curr_mm;
439 u32 saved_tid = info->tid;
440
441 /* If this function returns a non-NULL vma, it holds a reference to
442 * the task_struct, holds a refcount on mm->mm_users, and holds
443 * read lock on vma->mm->mmap_lock.
444 * If this function returns NULL, it does not hold any reference or
445 * lock.
446 */
447 if (info->task) {
448 curr_task = info->task;
449 curr_vma = info->vma;
450 curr_mm = info->mm;
451 /* In case of lock contention, drop mmap_lock to unblock
452 * the writer.
453 *
454 * After relock, call find(mm, prev_vm_end - 1) to find
455 * new vma to process.
456 *
457 * +------+------+-----------+
458 * | VMA1 | VMA2 | VMA3 |
459 * +------+------+-----------+
460 * | | | |
461 * 4k 8k 16k 400k
462 *
463 * For example, curr_vma == VMA2. Before unlock, we set
464 *
465 * prev_vm_start = 8k
466 * prev_vm_end = 16k
467 *
468 * There are a few cases:
469 *
470 * 1) VMA2 is freed, but VMA3 exists.
471 *
472 * find_vma() will return VMA3, just process VMA3.
473 *
474 * 2) VMA2 still exists.
475 *
476 * find_vma() will return VMA2, process VMA2->next.
477 *
478 * 3) no more vma in this mm.
479 *
480 * Process the next task.
481 *
482 * 4) find_vma() returns a different vma, VMA2'.
483 *
484 * 4.1) If VMA2 covers same range as VMA2', skip VMA2',
485 * because we already covered the range;
486 * 4.2) VMA2 and VMA2' covers different ranges, process
487 * VMA2'.
488 */
489 if (mmap_lock_is_contended(curr_mm)) {
490 info->prev_vm_start = curr_vma->vm_start;
491 info->prev_vm_end = curr_vma->vm_end;
492 op = task_vma_iter_find_vma;
493 mmap_read_unlock(curr_mm);
494 if (mmap_read_lock_killable(curr_mm)) {
495 mmput(curr_mm);
496 goto finish;
497 }
498 } else {
499 op = task_vma_iter_next_vma;
500 }
501 } else {
502again:
503 curr_task = task_seq_get_next(&info->common, &info->tid, true);
504 if (!curr_task) {
505 info->tid++;
506 goto finish;
507 }
508
509 if (saved_tid != info->tid) {
510 /* new task, process the first vma */
511 op = task_vma_iter_first_vma;
512 } else {
513 /* Found the same tid, which means the user space
514 * finished data in previous buffer and read more.
515 * We dropped mmap_lock before returning to user
516 * space, so it is necessary to use find_vma() to
517 * find the next vma to process.
518 */
519 op = task_vma_iter_find_vma;
520 }
521
522 curr_mm = get_task_mm(curr_task);
523 if (!curr_mm)
524 goto next_task;
525
526 if (mmap_read_lock_killable(curr_mm)) {
527 mmput(curr_mm);
528 goto finish;
529 }
530 }
531
532 switch (op) {
533 case task_vma_iter_first_vma:
534 curr_vma = find_vma(curr_mm, 0);
535 break;
536 case task_vma_iter_next_vma:
537 curr_vma = find_vma(curr_mm, curr_vma->vm_end);
538 break;
539 case task_vma_iter_find_vma:
540 /* We dropped mmap_lock so it is necessary to use find_vma
541 * to find the next vma. This is similar to the mechanism
542 * in show_smaps_rollup().
543 */
544 curr_vma = find_vma(curr_mm, info->prev_vm_end - 1);
545 /* case 1) and 4.2) above just use curr_vma */
546
547 /* check for case 2) or case 4.1) above */
548 if (curr_vma &&
549 curr_vma->vm_start == info->prev_vm_start &&
550 curr_vma->vm_end == info->prev_vm_end)
551 curr_vma = find_vma(curr_mm, curr_vma->vm_end);
552 break;
553 }
554 if (!curr_vma) {
555 /* case 3) above, or case 2) 4.1) with vma->next == NULL */
556 mmap_read_unlock(curr_mm);
557 mmput(curr_mm);
558 goto next_task;
559 }
560 info->task = curr_task;
561 info->vma = curr_vma;
562 info->mm = curr_mm;
563 return curr_vma;
564
565next_task:
566 if (info->common.type == BPF_TASK_ITER_TID)
567 goto finish;
568
569 put_task_struct(curr_task);
570 info->task = NULL;
571 info->mm = NULL;
572 info->tid++;
573 goto again;
574
575finish:
576 if (curr_task)
577 put_task_struct(curr_task);
578 info->task = NULL;
579 info->vma = NULL;
580 info->mm = NULL;
581 return NULL;
582}
583
584static void *task_vma_seq_start(struct seq_file *seq, loff_t *pos)
585{
586 struct bpf_iter_seq_task_vma_info *info = seq->private;
587 struct vm_area_struct *vma;
588
589 vma = task_vma_seq_get_next(info);
590 if (vma && *pos == 0)
591 ++*pos;
592
593 return vma;
594}
595
596static void *task_vma_seq_next(struct seq_file *seq, void *v, loff_t *pos)
597{
598 struct bpf_iter_seq_task_vma_info *info = seq->private;
599
600 ++*pos;
601 return task_vma_seq_get_next(info);
602}
603
604struct bpf_iter__task_vma {
605 __bpf_md_ptr(struct bpf_iter_meta *, meta);
606 __bpf_md_ptr(struct task_struct *, task);
607 __bpf_md_ptr(struct vm_area_struct *, vma);
608};
609
610DEFINE_BPF_ITER_FUNC(task_vma, struct bpf_iter_meta *meta,
611 struct task_struct *task, struct vm_area_struct *vma)
612
613static int __task_vma_seq_show(struct seq_file *seq, bool in_stop)
614{
615 struct bpf_iter_seq_task_vma_info *info = seq->private;
616 struct bpf_iter__task_vma ctx;
617 struct bpf_iter_meta meta;
618 struct bpf_prog *prog;
619
620 meta.seq = seq;
621 prog = bpf_iter_get_info(&meta, in_stop);
622 if (!prog)
623 return 0;
624
625 ctx.meta = &meta;
626 ctx.task = info->task;
627 ctx.vma = info->vma;
628 return bpf_iter_run_prog(prog, &ctx);
629}
630
631static int task_vma_seq_show(struct seq_file *seq, void *v)
632{
633 return __task_vma_seq_show(seq, false);
634}
635
636static void task_vma_seq_stop(struct seq_file *seq, void *v)
637{
638 struct bpf_iter_seq_task_vma_info *info = seq->private;
639
640 if (!v) {
641 (void)__task_vma_seq_show(seq, true);
642 } else {
643 /* info->vma has not been seen by the BPF program. If the
644 * user space reads more, task_vma_seq_get_next should
645 * return this vma again. Set prev_vm_start to ~0UL,
646 * so that we don't skip the vma returned by the next
647 * find_vma() (case task_vma_iter_find_vma in
648 * task_vma_seq_get_next()).
649 */
650 info->prev_vm_start = ~0UL;
651 info->prev_vm_end = info->vma->vm_end;
652 mmap_read_unlock(info->mm);
653 mmput(info->mm);
654 info->mm = NULL;
655 put_task_struct(info->task);
656 info->task = NULL;
657 }
658}
659
660static const struct seq_operations task_vma_seq_ops = {
661 .start = task_vma_seq_start,
662 .next = task_vma_seq_next,
663 .stop = task_vma_seq_stop,
664 .show = task_vma_seq_show,
665};
666
667static const struct bpf_iter_seq_info task_seq_info = {
668 .seq_ops = &task_seq_ops,
669 .init_seq_private = init_seq_pidns,
670 .fini_seq_private = fini_seq_pidns,
671 .seq_priv_size = sizeof(struct bpf_iter_seq_task_info),
672};
673
674static int bpf_iter_fill_link_info(const struct bpf_iter_aux_info *aux, struct bpf_link_info *info)
675{
676 switch (aux->task.type) {
677 case BPF_TASK_ITER_TID:
678 info->iter.task.tid = aux->task.pid;
679 break;
680 case BPF_TASK_ITER_TGID:
681 info->iter.task.pid = aux->task.pid;
682 break;
683 default:
684 break;
685 }
686 return 0;
687}
688
689static void bpf_iter_task_show_fdinfo(const struct bpf_iter_aux_info *aux, struct seq_file *seq)
690{
691 seq_printf(seq, "task_type:\t%s\n", iter_task_type_names[aux->task.type]);
692 if (aux->task.type == BPF_TASK_ITER_TID)
693 seq_printf(seq, "tid:\t%u\n", aux->task.pid);
694 else if (aux->task.type == BPF_TASK_ITER_TGID)
695 seq_printf(seq, "pid:\t%u\n", aux->task.pid);
696}
697
698static struct bpf_iter_reg task_reg_info = {
699 .target = "task",
700 .attach_target = bpf_iter_attach_task,
701 .feature = BPF_ITER_RESCHED,
702 .ctx_arg_info_size = 1,
703 .ctx_arg_info = {
704 { offsetof(struct bpf_iter__task, task),
705 PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
706 },
707 .seq_info = &task_seq_info,
708 .fill_link_info = bpf_iter_fill_link_info,
709 .show_fdinfo = bpf_iter_task_show_fdinfo,
710};
711
712static const struct bpf_iter_seq_info task_file_seq_info = {
713 .seq_ops = &task_file_seq_ops,
714 .init_seq_private = init_seq_pidns,
715 .fini_seq_private = fini_seq_pidns,
716 .seq_priv_size = sizeof(struct bpf_iter_seq_task_file_info),
717};
718
719static struct bpf_iter_reg task_file_reg_info = {
720 .target = "task_file",
721 .attach_target = bpf_iter_attach_task,
722 .feature = BPF_ITER_RESCHED,
723 .ctx_arg_info_size = 2,
724 .ctx_arg_info = {
725 { offsetof(struct bpf_iter__task_file, task),
726 PTR_TO_BTF_ID_OR_NULL },
727 { offsetof(struct bpf_iter__task_file, file),
728 PTR_TO_BTF_ID_OR_NULL },
729 },
730 .seq_info = &task_file_seq_info,
731 .fill_link_info = bpf_iter_fill_link_info,
732 .show_fdinfo = bpf_iter_task_show_fdinfo,
733};
734
735static const struct bpf_iter_seq_info task_vma_seq_info = {
736 .seq_ops = &task_vma_seq_ops,
737 .init_seq_private = init_seq_pidns,
738 .fini_seq_private = fini_seq_pidns,
739 .seq_priv_size = sizeof(struct bpf_iter_seq_task_vma_info),
740};
741
742static struct bpf_iter_reg task_vma_reg_info = {
743 .target = "task_vma",
744 .attach_target = bpf_iter_attach_task,
745 .feature = BPF_ITER_RESCHED,
746 .ctx_arg_info_size = 2,
747 .ctx_arg_info = {
748 { offsetof(struct bpf_iter__task_vma, task),
749 PTR_TO_BTF_ID_OR_NULL },
750 { offsetof(struct bpf_iter__task_vma, vma),
751 PTR_TO_BTF_ID_OR_NULL },
752 },
753 .seq_info = &task_vma_seq_info,
754 .fill_link_info = bpf_iter_fill_link_info,
755 .show_fdinfo = bpf_iter_task_show_fdinfo,
756};
757
758BPF_CALL_5(bpf_find_vma, struct task_struct *, task, u64, start,
759 bpf_callback_t, callback_fn, void *, callback_ctx, u64, flags)
760{
761 struct mmap_unlock_irq_work *work = NULL;
762 struct vm_area_struct *vma;
763 bool irq_work_busy = false;
764 struct mm_struct *mm;
765 int ret = -ENOENT;
766
767 if (flags)
768 return -EINVAL;
769
770 if (!task)
771 return -ENOENT;
772
773 mm = task->mm;
774 if (!mm)
775 return -ENOENT;
776
777 irq_work_busy = bpf_mmap_unlock_get_irq_work(&work);
778
779 if (irq_work_busy || !mmap_read_trylock(mm))
780 return -EBUSY;
781
782 vma = find_vma(mm, start);
783
784 if (vma && vma->vm_start <= start && vma->vm_end > start) {
785 callback_fn((u64)(long)task, (u64)(long)vma,
786 (u64)(long)callback_ctx, 0, 0);
787 ret = 0;
788 }
789 bpf_mmap_unlock_mm(work, mm);
790 return ret;
791}
792
793const struct bpf_func_proto bpf_find_vma_proto = {
794 .func = bpf_find_vma,
795 .ret_type = RET_INTEGER,
796 .arg1_type = ARG_PTR_TO_BTF_ID,
797 .arg1_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
798 .arg2_type = ARG_ANYTHING,
799 .arg3_type = ARG_PTR_TO_FUNC,
800 .arg4_type = ARG_PTR_TO_STACK_OR_NULL,
801 .arg5_type = ARG_ANYTHING,
802};
803
804struct bpf_iter_task_vma_kern_data {
805 struct task_struct *task;
806 struct mm_struct *mm;
807 struct mmap_unlock_irq_work *work;
808 struct vma_iterator vmi;
809};
810
811struct bpf_iter_task_vma {
812 /* opaque iterator state; having __u64 here allows to preserve correct
813 * alignment requirements in vmlinux.h, generated from BTF
814 */
815 __u64 __opaque[1];
816} __attribute__((aligned(8)));
817
818/* Non-opaque version of bpf_iter_task_vma */
819struct bpf_iter_task_vma_kern {
820 struct bpf_iter_task_vma_kern_data *data;
821} __attribute__((aligned(8)));
822
823__bpf_kfunc_start_defs();
824
825__bpf_kfunc int bpf_iter_task_vma_new(struct bpf_iter_task_vma *it,
826 struct task_struct *task, u64 addr)
827{
828 struct bpf_iter_task_vma_kern *kit = (void *)it;
829 bool irq_work_busy = false;
830 int err;
831
832 BUILD_BUG_ON(sizeof(struct bpf_iter_task_vma_kern) != sizeof(struct bpf_iter_task_vma));
833 BUILD_BUG_ON(__alignof__(struct bpf_iter_task_vma_kern) != __alignof__(struct bpf_iter_task_vma));
834
835 /* is_iter_reg_valid_uninit guarantees that kit hasn't been initialized
836 * before, so non-NULL kit->data doesn't point to previously
837 * bpf_mem_alloc'd bpf_iter_task_vma_kern_data
838 */
839 kit->data = bpf_mem_alloc(&bpf_global_ma, sizeof(struct bpf_iter_task_vma_kern_data));
840 if (!kit->data)
841 return -ENOMEM;
842
843 kit->data->task = get_task_struct(task);
844 kit->data->mm = task->mm;
845 if (!kit->data->mm) {
846 err = -ENOENT;
847 goto err_cleanup_iter;
848 }
849
850 /* kit->data->work == NULL is valid after bpf_mmap_unlock_get_irq_work */
851 irq_work_busy = bpf_mmap_unlock_get_irq_work(&kit->data->work);
852 if (irq_work_busy || !mmap_read_trylock(kit->data->mm)) {
853 err = -EBUSY;
854 goto err_cleanup_iter;
855 }
856
857 vma_iter_init(&kit->data->vmi, kit->data->mm, addr);
858 return 0;
859
860err_cleanup_iter:
861 if (kit->data->task)
862 put_task_struct(kit->data->task);
863 bpf_mem_free(&bpf_global_ma, kit->data);
864 /* NULL kit->data signals failed bpf_iter_task_vma initialization */
865 kit->data = NULL;
866 return err;
867}
868
869__bpf_kfunc struct vm_area_struct *bpf_iter_task_vma_next(struct bpf_iter_task_vma *it)
870{
871 struct bpf_iter_task_vma_kern *kit = (void *)it;
872
873 if (!kit->data) /* bpf_iter_task_vma_new failed */
874 return NULL;
875 return vma_next(&kit->data->vmi);
876}
877
878__bpf_kfunc void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it)
879{
880 struct bpf_iter_task_vma_kern *kit = (void *)it;
881
882 if (kit->data) {
883 bpf_mmap_unlock_mm(kit->data->work, kit->data->mm);
884 put_task_struct(kit->data->task);
885 bpf_mem_free(&bpf_global_ma, kit->data);
886 }
887}
888
889__bpf_kfunc_end_defs();
890
891#ifdef CONFIG_CGROUPS
892
893struct bpf_iter_css_task {
894 __u64 __opaque[1];
895} __attribute__((aligned(8)));
896
897struct bpf_iter_css_task_kern {
898 struct css_task_iter *css_it;
899} __attribute__((aligned(8)));
900
901__bpf_kfunc_start_defs();
902
903__bpf_kfunc int bpf_iter_css_task_new(struct bpf_iter_css_task *it,
904 struct cgroup_subsys_state *css, unsigned int flags)
905{
906 struct bpf_iter_css_task_kern *kit = (void *)it;
907
908 BUILD_BUG_ON(sizeof(struct bpf_iter_css_task_kern) != sizeof(struct bpf_iter_css_task));
909 BUILD_BUG_ON(__alignof__(struct bpf_iter_css_task_kern) !=
910 __alignof__(struct bpf_iter_css_task));
911 kit->css_it = NULL;
912 switch (flags) {
913 case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
914 case CSS_TASK_ITER_PROCS:
915 case 0:
916 break;
917 default:
918 return -EINVAL;
919 }
920
921 kit->css_it = bpf_mem_alloc(&bpf_global_ma, sizeof(struct css_task_iter));
922 if (!kit->css_it)
923 return -ENOMEM;
924 css_task_iter_start(css, flags, kit->css_it);
925 return 0;
926}
927
928__bpf_kfunc struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it)
929{
930 struct bpf_iter_css_task_kern *kit = (void *)it;
931
932 if (!kit->css_it)
933 return NULL;
934 return css_task_iter_next(kit->css_it);
935}
936
937__bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it)
938{
939 struct bpf_iter_css_task_kern *kit = (void *)it;
940
941 if (!kit->css_it)
942 return;
943 css_task_iter_end(kit->css_it);
944 bpf_mem_free(&bpf_global_ma, kit->css_it);
945}
946
947__bpf_kfunc_end_defs();
948
949#endif /* CONFIG_CGROUPS */
950
951struct bpf_iter_task {
952 __u64 __opaque[3];
953} __attribute__((aligned(8)));
954
955struct bpf_iter_task_kern {
956 struct task_struct *task;
957 struct task_struct *pos;
958 unsigned int flags;
959} __attribute__((aligned(8)));
960
961enum {
962 /* all process in the system */
963 BPF_TASK_ITER_ALL_PROCS,
964 /* all threads in the system */
965 BPF_TASK_ITER_ALL_THREADS,
966 /* all threads of a specific process */
967 BPF_TASK_ITER_PROC_THREADS
968};
969
970__bpf_kfunc_start_defs();
971
972__bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it,
973 struct task_struct *task__nullable, unsigned int flags)
974{
975 struct bpf_iter_task_kern *kit = (void *)it;
976
977 BUILD_BUG_ON(sizeof(struct bpf_iter_task_kern) > sizeof(struct bpf_iter_task));
978 BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) !=
979 __alignof__(struct bpf_iter_task));
980
981 kit->pos = NULL;
982
983 switch (flags) {
984 case BPF_TASK_ITER_ALL_THREADS:
985 case BPF_TASK_ITER_ALL_PROCS:
986 break;
987 case BPF_TASK_ITER_PROC_THREADS:
988 if (!task__nullable)
989 return -EINVAL;
990 break;
991 default:
992 return -EINVAL;
993 }
994
995 if (flags == BPF_TASK_ITER_PROC_THREADS)
996 kit->task = task__nullable;
997 else
998 kit->task = &init_task;
999 kit->pos = kit->task;
1000 kit->flags = flags;
1001 return 0;
1002}
1003
1004__bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it)
1005{
1006 struct bpf_iter_task_kern *kit = (void *)it;
1007 struct task_struct *pos;
1008 unsigned int flags;
1009
1010 flags = kit->flags;
1011 pos = kit->pos;
1012
1013 if (!pos)
1014 return pos;
1015
1016 if (flags == BPF_TASK_ITER_ALL_PROCS)
1017 goto get_next_task;
1018
1019 kit->pos = __next_thread(kit->pos);
1020 if (kit->pos || flags == BPF_TASK_ITER_PROC_THREADS)
1021 return pos;
1022
1023get_next_task:
1024 kit->task = next_task(kit->task);
1025 if (kit->task == &init_task)
1026 kit->pos = NULL;
1027 else
1028 kit->pos = kit->task;
1029
1030 return pos;
1031}
1032
1033__bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it)
1034{
1035}
1036
1037__bpf_kfunc_end_defs();
1038
1039DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
1040
1041static void do_mmap_read_unlock(struct irq_work *entry)
1042{
1043 struct mmap_unlock_irq_work *work;
1044
1045 if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT)))
1046 return;
1047
1048 work = container_of(entry, struct mmap_unlock_irq_work, irq_work);
1049 mmap_read_unlock_non_owner(work->mm);
1050}
1051
1052static int __init task_iter_init(void)
1053{
1054 struct mmap_unlock_irq_work *work;
1055 int ret, cpu;
1056
1057 for_each_possible_cpu(cpu) {
1058 work = per_cpu_ptr(&mmap_unlock_work, cpu);
1059 init_irq_work(&work->irq_work, do_mmap_read_unlock);
1060 }
1061
1062 task_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
1063 ret = bpf_iter_reg_target(&task_reg_info);
1064 if (ret)
1065 return ret;
1066
1067 task_file_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
1068 task_file_reg_info.ctx_arg_info[1].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_FILE];
1069 ret = bpf_iter_reg_target(&task_file_reg_info);
1070 if (ret)
1071 return ret;
1072
1073 task_vma_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
1074 task_vma_reg_info.ctx_arg_info[1].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA];
1075 return bpf_iter_reg_target(&task_vma_reg_info);
1076}
1077late_initcall(task_iter_init);