xref: /linux/tools/testing/selftests/cgroup/cgroup_util.c (revision b6a1af0362b3232c7b474b9b46e49b862602018c) 
1 /* SPDX-License-Identifier: GPL-2.0 */
2 
3 #define _GNU_SOURCE
4 
5 #include <errno.h>
6 #include <fcntl.h>
7 #include <linux/limits.h>
8 #include <poll.h>
9 #include <signal.h>
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <string.h>
13 #include <sys/inotify.h>
14 #include <sys/stat.h>
15 #include <sys/types.h>
16 #include <sys/wait.h>
17 #include <unistd.h>
18 
19 #include "cgroup_util.h"
20 #include "../clone3/clone3_selftests.h"
21 
22 /* Returns read len on success, or -errno on failure. */
23 static ssize_t read_text(const char *path, char *buf, size_t max_len)
24 {
25 	ssize_t len;
26 	int fd;
27 
28 	fd = open(path, O_RDONLY);
29 	if (fd < 0)
30 		return -errno;
31 
32 	len = read(fd, buf, max_len - 1);
33 
34 	if (len >= 0)
35 		buf[len] = 0;
36 
37 	close(fd);
38 	return len < 0 ? -errno : len;
39 }
40 
41 /* Returns written len on success, or -errno on failure. */
42 static ssize_t write_text(const char *path, char *buf, ssize_t len)
43 {
44 	int fd;
45 
46 	fd = open(path, O_WRONLY | O_APPEND);
47 	if (fd < 0)
48 		return -errno;
49 
50 	len = write(fd, buf, len);
51 	close(fd);
52 	return len < 0 ? -errno : len;
53 }
54 
55 char *cg_name(const char *root, const char *name)
56 {
57 	size_t len = strlen(root) + strlen(name) + 2;
58 	char *ret = malloc(len);
59 
60 	snprintf(ret, len, "%s/%s", root, name);
61 
62 	return ret;
63 }
64 
65 char *cg_name_indexed(const char *root, const char *name, int index)
66 {
67 	size_t len = strlen(root) + strlen(name) + 10;
68 	char *ret = malloc(len);
69 
70 	snprintf(ret, len, "%s/%s_%d", root, name, index);
71 
72 	return ret;
73 }
74 
75 char *cg_control(const char *cgroup, const char *control)
76 {
77 	size_t len = strlen(cgroup) + strlen(control) + 2;
78 	char *ret = malloc(len);
79 
80 	snprintf(ret, len, "%s/%s", cgroup, control);
81 
82 	return ret;
83 }
84 
85 /* Returns 0 on success, or -errno on failure. */
86 int cg_read(const char *cgroup, const char *control, char *buf, size_t len)
87 {
88 	char path[PATH_MAX];
89 	ssize_t ret;
90 
91 	snprintf(path, sizeof(path), "%s/%s", cgroup, control);
92 
93 	ret = read_text(path, buf, len);
94 	return ret >= 0 ? 0 : ret;
95 }
96 
97 int cg_read_strcmp(const char *cgroup, const char *control,
98 		   const char *expected)
99 {
100 	size_t size;
101 	char *buf;
102 	int ret;
103 
104 	/* Handle the case of comparing against empty string */
105 	if (!expected)
106 		return -1;
107 	else
108 		size = strlen(expected) + 1;
109 
110 	buf = malloc(size);
111 	if (!buf)
112 		return -1;
113 
114 	if (cg_read(cgroup, control, buf, size)) {
115 		free(buf);
116 		return -1;
117 	}
118 
119 	ret = strcmp(expected, buf);
120 	free(buf);
121 	return ret;
122 }
123 
124 int cg_read_strstr(const char *cgroup, const char *control, const char *needle)
125 {
126 	char buf[PAGE_SIZE];
127 
128 	if (cg_read(cgroup, control, buf, sizeof(buf)))
129 		return -1;
130 
131 	return strstr(buf, needle) ? 0 : -1;
132 }
133 
134 long cg_read_long(const char *cgroup, const char *control)
135 {
136 	char buf[128];
137 
138 	if (cg_read(cgroup, control, buf, sizeof(buf)))
139 		return -1;
140 
141 	return atol(buf);
142 }
143 
144 long cg_read_key_long(const char *cgroup, const char *control, const char *key)
145 {
146 	char buf[PAGE_SIZE];
147 	char *ptr;
148 
149 	if (cg_read(cgroup, control, buf, sizeof(buf)))
150 		return -1;
151 
152 	ptr = strstr(buf, key);
153 	if (!ptr)
154 		return -1;
155 
156 	return atol(ptr + strlen(key));
157 }
158 
159 long cg_read_lc(const char *cgroup, const char *control)
160 {
161 	char buf[PAGE_SIZE];
162 	const char delim[] = "\n";
163 	char *line;
164 	long cnt = 0;
165 
166 	if (cg_read(cgroup, control, buf, sizeof(buf)))
167 		return -1;
168 
169 	for (line = strtok(buf, delim); line; line = strtok(NULL, delim))
170 		cnt++;
171 
172 	return cnt;
173 }
174 
175 /* Returns 0 on success, or -errno on failure. */
176 int cg_write(const char *cgroup, const char *control, char *buf)
177 {
178 	char path[PATH_MAX];
179 	ssize_t len = strlen(buf), ret;
180 
181 	snprintf(path, sizeof(path), "%s/%s", cgroup, control);
182 	ret = write_text(path, buf, len);
183 	return ret == len ? 0 : ret;
184 }
185 
186 int cg_write_numeric(const char *cgroup, const char *control, long value)
187 {
188 	char buf[64];
189 	int ret;
190 
191 	ret = sprintf(buf, "%lu", value);
192 	if (ret < 0)
193 		return ret;
194 
195 	return cg_write(cgroup, control, buf);
196 }
197 
198 int cg_find_unified_root(char *root, size_t len)
199 {
200 	char buf[10 * PAGE_SIZE];
201 	char *fs, *mount, *type;
202 	const char delim[] = "\n\t ";
203 
204 	if (read_text("/proc/self/mounts", buf, sizeof(buf)) <= 0)
205 		return -1;
206 
207 	/*
208 	 * Example:
209 	 * cgroup /sys/fs/cgroup cgroup2 rw,seclabel,noexec,relatime 0 0
210 	 */
211 	for (fs = strtok(buf, delim); fs; fs = strtok(NULL, delim)) {
212 		mount = strtok(NULL, delim);
213 		type = strtok(NULL, delim);
214 		strtok(NULL, delim);
215 		strtok(NULL, delim);
216 		strtok(NULL, delim);
217 
218 		if (strcmp(type, "cgroup2") == 0) {
219 			strncpy(root, mount, len);
220 			return 0;
221 		}
222 	}
223 
224 	return -1;
225 }
226 
227 int cg_create(const char *cgroup)
228 {
229 	return mkdir(cgroup, 0755);
230 }
231 
232 int cg_wait_for_proc_count(const char *cgroup, int count)
233 {
234 	char buf[10 * PAGE_SIZE] = {0};
235 	int attempts;
236 	char *ptr;
237 
238 	for (attempts = 10; attempts >= 0; attempts--) {
239 		int nr = 0;
240 
241 		if (cg_read(cgroup, "cgroup.procs", buf, sizeof(buf)))
242 			break;
243 
244 		for (ptr = buf; *ptr; ptr++)
245 			if (*ptr == '\n')
246 				nr++;
247 
248 		if (nr >= count)
249 			return 0;
250 
251 		usleep(100000);
252 	}
253 
254 	return -1;
255 }
256 
257 int cg_killall(const char *cgroup)
258 {
259 	char buf[PAGE_SIZE];
260 	char *ptr = buf;
261 
262 	/* If cgroup.kill exists use it. */
263 	if (!cg_write(cgroup, "cgroup.kill", "1"))
264 		return 0;
265 
266 	if (cg_read(cgroup, "cgroup.procs", buf, sizeof(buf)))
267 		return -1;
268 
269 	while (ptr < buf + sizeof(buf)) {
270 		int pid = strtol(ptr, &ptr, 10);
271 
272 		if (pid == 0)
273 			break;
274 		if (*ptr)
275 			ptr++;
276 		else
277 			break;
278 		if (kill(pid, SIGKILL))
279 			return -1;
280 	}
281 
282 	return 0;
283 }
284 
285 int cg_destroy(const char *cgroup)
286 {
287 	int ret;
288 
289 retry:
290 	ret = rmdir(cgroup);
291 	if (ret && errno == EBUSY) {
292 		cg_killall(cgroup);
293 		usleep(100);
294 		goto retry;
295 	}
296 
297 	if (ret && errno == ENOENT)
298 		ret = 0;
299 
300 	return ret;
301 }
302 
303 int cg_enter(const char *cgroup, int pid)
304 {
305 	char pidbuf[64];
306 
307 	snprintf(pidbuf, sizeof(pidbuf), "%d", pid);
308 	return cg_write(cgroup, "cgroup.procs", pidbuf);
309 }
310 
311 int cg_enter_current(const char *cgroup)
312 {
313 	return cg_write(cgroup, "cgroup.procs", "0");
314 }
315 
316 int cg_enter_current_thread(const char *cgroup)
317 {
318 	return cg_write(cgroup, "cgroup.threads", "0");
319 }
320 
321 int cg_run(const char *cgroup,
322 	   int (*fn)(const char *cgroup, void *arg),
323 	   void *arg)
324 {
325 	int pid, retcode;
326 
327 	pid = fork();
328 	if (pid < 0) {
329 		return pid;
330 	} else if (pid == 0) {
331 		char buf[64];
332 
333 		snprintf(buf, sizeof(buf), "%d", getpid());
334 		if (cg_write(cgroup, "cgroup.procs", buf))
335 			exit(EXIT_FAILURE);
336 		exit(fn(cgroup, arg));
337 	} else {
338 		waitpid(pid, &retcode, 0);
339 		if (WIFEXITED(retcode))
340 			return WEXITSTATUS(retcode);
341 		else
342 			return -1;
343 	}
344 }
345 
346 pid_t clone_into_cgroup(int cgroup_fd)
347 {
348 #ifdef CLONE_ARGS_SIZE_VER2
349 	pid_t pid;
350 
351 	struct __clone_args args = {
352 		.flags = CLONE_INTO_CGROUP,
353 		.exit_signal = SIGCHLD,
354 		.cgroup = cgroup_fd,
355 	};
356 
357 	pid = sys_clone3(&args, sizeof(struct __clone_args));
358 	/*
359 	 * Verify that this is a genuine test failure:
360 	 * ENOSYS -> clone3() not available
361 	 * E2BIG  -> CLONE_INTO_CGROUP not available
362 	 */
363 	if (pid < 0 && (errno == ENOSYS || errno == E2BIG))
364 		goto pretend_enosys;
365 
366 	return pid;
367 
368 pretend_enosys:
369 #endif
370 	errno = ENOSYS;
371 	return -ENOSYS;
372 }
373 
374 int clone_reap(pid_t pid, int options)
375 {
376 	int ret;
377 	siginfo_t info = {
378 		.si_signo = 0,
379 	};
380 
381 again:
382 	ret = waitid(P_PID, pid, &info, options | __WALL | __WNOTHREAD);
383 	if (ret < 0) {
384 		if (errno == EINTR)
385 			goto again;
386 		return -1;
387 	}
388 
389 	if (options & WEXITED) {
390 		if (WIFEXITED(info.si_status))
391 			return WEXITSTATUS(info.si_status);
392 	}
393 
394 	if (options & WSTOPPED) {
395 		if (WIFSTOPPED(info.si_status))
396 			return WSTOPSIG(info.si_status);
397 	}
398 
399 	if (options & WCONTINUED) {
400 		if (WIFCONTINUED(info.si_status))
401 			return 0;
402 	}
403 
404 	return -1;
405 }
406 
407 int dirfd_open_opath(const char *dir)
408 {
409 	return open(dir, O_DIRECTORY | O_CLOEXEC | O_NOFOLLOW | O_PATH);
410 }
411 
412 #define close_prot_errno(fd)                                                   \
413 	if (fd >= 0) {                                                         \
414 		int _e_ = errno;                                               \
415 		close(fd);                                                     \
416 		errno = _e_;                                                   \
417 	}
418 
419 static int clone_into_cgroup_run_nowait(const char *cgroup,
420 					int (*fn)(const char *cgroup, void *arg),
421 					void *arg)
422 {
423 	int cgroup_fd;
424 	pid_t pid;
425 
426 	cgroup_fd =  dirfd_open_opath(cgroup);
427 	if (cgroup_fd < 0)
428 		return -1;
429 
430 	pid = clone_into_cgroup(cgroup_fd);
431 	close_prot_errno(cgroup_fd);
432 	if (pid == 0)
433 		exit(fn(cgroup, arg));
434 
435 	return pid;
436 }
437 
438 int cg_run_nowait(const char *cgroup,
439 		  int (*fn)(const char *cgroup, void *arg),
440 		  void *arg)
441 {
442 	int pid;
443 
444 	pid = clone_into_cgroup_run_nowait(cgroup, fn, arg);
445 	if (pid > 0)
446 		return pid;
447 
448 	/* Genuine test failure. */
449 	if (pid < 0 && errno != ENOSYS)
450 		return -1;
451 
452 	pid = fork();
453 	if (pid == 0) {
454 		char buf[64];
455 
456 		snprintf(buf, sizeof(buf), "%d", getpid());
457 		if (cg_write(cgroup, "cgroup.procs", buf))
458 			exit(EXIT_FAILURE);
459 		exit(fn(cgroup, arg));
460 	}
461 
462 	return pid;
463 }
464 
465 int get_temp_fd(void)
466 {
467 	return open(".", O_TMPFILE | O_RDWR | O_EXCL);
468 }
469 
470 int alloc_pagecache(int fd, size_t size)
471 {
472 	char buf[PAGE_SIZE];
473 	struct stat st;
474 	int i;
475 
476 	if (fstat(fd, &st))
477 		goto cleanup;
478 
479 	size += st.st_size;
480 
481 	if (ftruncate(fd, size))
482 		goto cleanup;
483 
484 	for (i = 0; i < size; i += sizeof(buf))
485 		read(fd, buf, sizeof(buf));
486 
487 	return 0;
488 
489 cleanup:
490 	return -1;
491 }
492 
493 int alloc_anon(const char *cgroup, void *arg)
494 {
495 	size_t size = (unsigned long)arg;
496 	char *buf, *ptr;
497 
498 	buf = malloc(size);
499 	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
500 		*ptr = 0;
501 
502 	free(buf);
503 	return 0;
504 }
505 
506 int is_swap_enabled(void)
507 {
508 	char buf[PAGE_SIZE];
509 	const char delim[] = "\n";
510 	int cnt = 0;
511 	char *line;
512 
513 	if (read_text("/proc/swaps", buf, sizeof(buf)) <= 0)
514 		return -1;
515 
516 	for (line = strtok(buf, delim); line; line = strtok(NULL, delim))
517 		cnt++;
518 
519 	return cnt > 1;
520 }
521 
522 int set_oom_adj_score(int pid, int score)
523 {
524 	char path[PATH_MAX];
525 	int fd, len;
526 
527 	sprintf(path, "/proc/%d/oom_score_adj", pid);
528 
529 	fd = open(path, O_WRONLY | O_APPEND);
530 	if (fd < 0)
531 		return fd;
532 
533 	len = dprintf(fd, "%d", score);
534 	if (len < 0) {
535 		close(fd);
536 		return len;
537 	}
538 
539 	close(fd);
540 	return 0;
541 }
542 
543 int proc_mount_contains(const char *option)
544 {
545 	char buf[4 * PAGE_SIZE];
546 	ssize_t read;
547 
548 	read = read_text("/proc/mounts", buf, sizeof(buf));
549 	if (read < 0)
550 		return read;
551 
552 	return strstr(buf, option) != NULL;
553 }
554 
555 ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size)
556 {
557 	char path[PATH_MAX];
558 	ssize_t ret;
559 
560 	if (!pid)
561 		snprintf(path, sizeof(path), "/proc/%s/%s",
562 			 thread ? "thread-self" : "self", item);
563 	else
564 		snprintf(path, sizeof(path), "/proc/%d/%s", pid, item);
565 
566 	ret = read_text(path, buf, size);
567 	return ret < 0 ? -1 : ret;
568 }
569 
570 int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)
571 {
572 	char buf[PAGE_SIZE];
573 
574 	if (proc_read_text(pid, thread, item, buf, sizeof(buf)) < 0)
575 		return -1;
576 
577 	return strstr(buf, needle) ? 0 : -1;
578 }
579 
580 int clone_into_cgroup_run_wait(const char *cgroup)
581 {
582 	int cgroup_fd;
583 	pid_t pid;
584 
585 	cgroup_fd =  dirfd_open_opath(cgroup);
586 	if (cgroup_fd < 0)
587 		return -1;
588 
589 	pid = clone_into_cgroup(cgroup_fd);
590 	close_prot_errno(cgroup_fd);
591 	if (pid < 0)
592 		return -1;
593 
594 	if (pid == 0)
595 		exit(EXIT_SUCCESS);
596 
597 	/*
598 	 * We don't care whether this fails. We only care whether the initial
599 	 * clone succeeded.
600 	 */
601 	(void)clone_reap(pid, WEXITED);
602 	return 0;
603 }
604 
605 static int __prepare_for_wait(const char *cgroup, const char *filename)
606 {
607 	int fd, ret = -1;
608 
609 	fd = inotify_init1(0);
610 	if (fd == -1)
611 		return fd;
612 
613 	ret = inotify_add_watch(fd, cg_control(cgroup, filename), IN_MODIFY);
614 	if (ret == -1) {
615 		close(fd);
616 		fd = -1;
617 	}
618 
619 	return fd;
620 }
621 
622 int cg_prepare_for_wait(const char *cgroup)
623 {
624 	return __prepare_for_wait(cgroup, "cgroup.events");
625 }
626 
627 int memcg_prepare_for_wait(const char *cgroup)
628 {
629 	return __prepare_for_wait(cgroup, "memory.events");
630 }
631 
632 int cg_wait_for(int fd)
633 {
634 	int ret = -1;
635 	struct pollfd fds = {
636 		.fd = fd,
637 		.events = POLLIN,
638 	};
639 
640 	while (true) {
641 		ret = poll(&fds, 1, 10000);
642 
643 		if (ret == -1) {
644 			if (errno == EINTR)
645 				continue;
646 
647 			break;
648 		}
649 
650 		if (ret > 0 && fds.revents & POLLIN) {
651 			ret = 0;
652 			break;
653 		}
654 	}
655 
656 	return ret;
657 }
658