xref: /linux/tools/testing/selftests/cgroup/cgroup_util.c (revision e7d759f31ca295d589f7420719c311870bb3166f) 
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 	if (!cgroup)
290 		return 0;
291 retry:
292 	ret = rmdir(cgroup);
293 	if (ret && errno == EBUSY) {
294 		cg_killall(cgroup);
295 		usleep(100);
296 		goto retry;
297 	}
298 
299 	if (ret && errno == ENOENT)
300 		ret = 0;
301 
302 	return ret;
303 }
304 
305 int cg_enter(const char *cgroup, int pid)
306 {
307 	char pidbuf[64];
308 
309 	snprintf(pidbuf, sizeof(pidbuf), "%d", pid);
310 	return cg_write(cgroup, "cgroup.procs", pidbuf);
311 }
312 
313 int cg_enter_current(const char *cgroup)
314 {
315 	return cg_write(cgroup, "cgroup.procs", "0");
316 }
317 
318 int cg_enter_current_thread(const char *cgroup)
319 {
320 	return cg_write(cgroup, "cgroup.threads", "0");
321 }
322 
323 int cg_run(const char *cgroup,
324 	   int (*fn)(const char *cgroup, void *arg),
325 	   void *arg)
326 {
327 	int pid, retcode;
328 
329 	pid = fork();
330 	if (pid < 0) {
331 		return pid;
332 	} else if (pid == 0) {
333 		char buf[64];
334 
335 		snprintf(buf, sizeof(buf), "%d", getpid());
336 		if (cg_write(cgroup, "cgroup.procs", buf))
337 			exit(EXIT_FAILURE);
338 		exit(fn(cgroup, arg));
339 	} else {
340 		waitpid(pid, &retcode, 0);
341 		if (WIFEXITED(retcode))
342 			return WEXITSTATUS(retcode);
343 		else
344 			return -1;
345 	}
346 }
347 
348 pid_t clone_into_cgroup(int cgroup_fd)
349 {
350 #ifdef CLONE_ARGS_SIZE_VER2
351 	pid_t pid;
352 
353 	struct __clone_args args = {
354 		.flags = CLONE_INTO_CGROUP,
355 		.exit_signal = SIGCHLD,
356 		.cgroup = cgroup_fd,
357 	};
358 
359 	pid = sys_clone3(&args, sizeof(struct __clone_args));
360 	/*
361 	 * Verify that this is a genuine test failure:
362 	 * ENOSYS -> clone3() not available
363 	 * E2BIG  -> CLONE_INTO_CGROUP not available
364 	 */
365 	if (pid < 0 && (errno == ENOSYS || errno == E2BIG))
366 		goto pretend_enosys;
367 
368 	return pid;
369 
370 pretend_enosys:
371 #endif
372 	errno = ENOSYS;
373 	return -ENOSYS;
374 }
375 
376 int clone_reap(pid_t pid, int options)
377 {
378 	int ret;
379 	siginfo_t info = {
380 		.si_signo = 0,
381 	};
382 
383 again:
384 	ret = waitid(P_PID, pid, &info, options | __WALL | __WNOTHREAD);
385 	if (ret < 0) {
386 		if (errno == EINTR)
387 			goto again;
388 		return -1;
389 	}
390 
391 	if (options & WEXITED) {
392 		if (WIFEXITED(info.si_status))
393 			return WEXITSTATUS(info.si_status);
394 	}
395 
396 	if (options & WSTOPPED) {
397 		if (WIFSTOPPED(info.si_status))
398 			return WSTOPSIG(info.si_status);
399 	}
400 
401 	if (options & WCONTINUED) {
402 		if (WIFCONTINUED(info.si_status))
403 			return 0;
404 	}
405 
406 	return -1;
407 }
408 
409 int dirfd_open_opath(const char *dir)
410 {
411 	return open(dir, O_DIRECTORY | O_CLOEXEC | O_NOFOLLOW | O_PATH);
412 }
413 
414 #define close_prot_errno(fd)                                                   \
415 	if (fd >= 0) {                                                         \
416 		int _e_ = errno;                                               \
417 		close(fd);                                                     \
418 		errno = _e_;                                                   \
419 	}
420 
421 static int clone_into_cgroup_run_nowait(const char *cgroup,
422 					int (*fn)(const char *cgroup, void *arg),
423 					void *arg)
424 {
425 	int cgroup_fd;
426 	pid_t pid;
427 
428 	cgroup_fd =  dirfd_open_opath(cgroup);
429 	if (cgroup_fd < 0)
430 		return -1;
431 
432 	pid = clone_into_cgroup(cgroup_fd);
433 	close_prot_errno(cgroup_fd);
434 	if (pid == 0)
435 		exit(fn(cgroup, arg));
436 
437 	return pid;
438 }
439 
440 int cg_run_nowait(const char *cgroup,
441 		  int (*fn)(const char *cgroup, void *arg),
442 		  void *arg)
443 {
444 	int pid;
445 
446 	pid = clone_into_cgroup_run_nowait(cgroup, fn, arg);
447 	if (pid > 0)
448 		return pid;
449 
450 	/* Genuine test failure. */
451 	if (pid < 0 && errno != ENOSYS)
452 		return -1;
453 
454 	pid = fork();
455 	if (pid == 0) {
456 		char buf[64];
457 
458 		snprintf(buf, sizeof(buf), "%d", getpid());
459 		if (cg_write(cgroup, "cgroup.procs", buf))
460 			exit(EXIT_FAILURE);
461 		exit(fn(cgroup, arg));
462 	}
463 
464 	return pid;
465 }
466 
467 int get_temp_fd(void)
468 {
469 	return open(".", O_TMPFILE | O_RDWR | O_EXCL);
470 }
471 
472 int alloc_pagecache(int fd, size_t size)
473 {
474 	char buf[PAGE_SIZE];
475 	struct stat st;
476 	int i;
477 
478 	if (fstat(fd, &st))
479 		goto cleanup;
480 
481 	size += st.st_size;
482 
483 	if (ftruncate(fd, size))
484 		goto cleanup;
485 
486 	for (i = 0; i < size; i += sizeof(buf))
487 		read(fd, buf, sizeof(buf));
488 
489 	return 0;
490 
491 cleanup:
492 	return -1;
493 }
494 
495 int alloc_anon(const char *cgroup, void *arg)
496 {
497 	size_t size = (unsigned long)arg;
498 	char *buf, *ptr;
499 
500 	buf = malloc(size);
501 	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
502 		*ptr = 0;
503 
504 	free(buf);
505 	return 0;
506 }
507 
508 int is_swap_enabled(void)
509 {
510 	char buf[PAGE_SIZE];
511 	const char delim[] = "\n";
512 	int cnt = 0;
513 	char *line;
514 
515 	if (read_text("/proc/swaps", buf, sizeof(buf)) <= 0)
516 		return -1;
517 
518 	for (line = strtok(buf, delim); line; line = strtok(NULL, delim))
519 		cnt++;
520 
521 	return cnt > 1;
522 }
523 
524 int set_oom_adj_score(int pid, int score)
525 {
526 	char path[PATH_MAX];
527 	int fd, len;
528 
529 	sprintf(path, "/proc/%d/oom_score_adj", pid);
530 
531 	fd = open(path, O_WRONLY | O_APPEND);
532 	if (fd < 0)
533 		return fd;
534 
535 	len = dprintf(fd, "%d", score);
536 	if (len < 0) {
537 		close(fd);
538 		return len;
539 	}
540 
541 	close(fd);
542 	return 0;
543 }
544 
545 int proc_mount_contains(const char *option)
546 {
547 	char buf[4 * PAGE_SIZE];
548 	ssize_t read;
549 
550 	read = read_text("/proc/mounts", buf, sizeof(buf));
551 	if (read < 0)
552 		return read;
553 
554 	return strstr(buf, option) != NULL;
555 }
556 
557 ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size)
558 {
559 	char path[PATH_MAX];
560 	ssize_t ret;
561 
562 	if (!pid)
563 		snprintf(path, sizeof(path), "/proc/%s/%s",
564 			 thread ? "thread-self" : "self", item);
565 	else
566 		snprintf(path, sizeof(path), "/proc/%d/%s", pid, item);
567 
568 	ret = read_text(path, buf, size);
569 	return ret < 0 ? -1 : ret;
570 }
571 
572 int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)
573 {
574 	char buf[PAGE_SIZE];
575 
576 	if (proc_read_text(pid, thread, item, buf, sizeof(buf)) < 0)
577 		return -1;
578 
579 	return strstr(buf, needle) ? 0 : -1;
580 }
581 
582 int clone_into_cgroup_run_wait(const char *cgroup)
583 {
584 	int cgroup_fd;
585 	pid_t pid;
586 
587 	cgroup_fd =  dirfd_open_opath(cgroup);
588 	if (cgroup_fd < 0)
589 		return -1;
590 
591 	pid = clone_into_cgroup(cgroup_fd);
592 	close_prot_errno(cgroup_fd);
593 	if (pid < 0)
594 		return -1;
595 
596 	if (pid == 0)
597 		exit(EXIT_SUCCESS);
598 
599 	/*
600 	 * We don't care whether this fails. We only care whether the initial
601 	 * clone succeeded.
602 	 */
603 	(void)clone_reap(pid, WEXITED);
604 	return 0;
605 }
606 
607 static int __prepare_for_wait(const char *cgroup, const char *filename)
608 {
609 	int fd, ret = -1;
610 
611 	fd = inotify_init1(0);
612 	if (fd == -1)
613 		return fd;
614 
615 	ret = inotify_add_watch(fd, cg_control(cgroup, filename), IN_MODIFY);
616 	if (ret == -1) {
617 		close(fd);
618 		fd = -1;
619 	}
620 
621 	return fd;
622 }
623 
624 int cg_prepare_for_wait(const char *cgroup)
625 {
626 	return __prepare_for_wait(cgroup, "cgroup.events");
627 }
628 
629 int memcg_prepare_for_wait(const char *cgroup)
630 {
631 	return __prepare_for_wait(cgroup, "memory.events");
632 }
633 
634 int cg_wait_for(int fd)
635 {
636 	int ret = -1;
637 	struct pollfd fds = {
638 		.fd = fd,
639 		.events = POLLIN,
640 	};
641 
642 	while (true) {
643 		ret = poll(&fds, 1, 10000);
644 
645 		if (ret == -1) {
646 			if (errno == EINTR)
647 				continue;
648 
649 			break;
650 		}
651 
652 		if (ret > 0 && fds.revents & POLLIN) {
653 			ret = 0;
654 			break;
655 		}
656 	}
657 
658 	return ret;
659 }
660