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. */
read_text(const char * path,char * buf,size_t max_len)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. */
write_text(const char * path,char * buf,ssize_t len)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
cg_name(const char * root,const char * name)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
cg_name_indexed(const char * root,const char * name,int index)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
cg_control(const char * cgroup,const char * control)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. */
cg_read(const char * cgroup,const char * control,char * buf,size_t len)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
cg_read_strcmp(const char * cgroup,const char * control,const char * expected)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
cg_read_strstr(const char * cgroup,const char * control,const char * needle)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
cg_read_long(const char * cgroup,const char * control)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
cg_read_key_long(const char * cgroup,const char * control,const char * key)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
cg_read_lc(const char * cgroup,const char * control)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. */
cg_write(const char * cgroup,const char * control,char * buf)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
cg_write_numeric(const char * cgroup,const char * control,long value)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
cg_find_unified_root(char * root,size_t len)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
cg_create(const char * cgroup)227 int cg_create(const char *cgroup)
228 {
229 return mkdir(cgroup, 0755);
230 }
231
cg_wait_for_proc_count(const char * cgroup,int count)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
cg_killall(const char * cgroup)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
cg_destroy(const char * cgroup)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
cg_enter(const char * cgroup,int pid)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
cg_enter_current(const char * cgroup)313 int cg_enter_current(const char *cgroup)
314 {
315 return cg_write(cgroup, "cgroup.procs", "0");
316 }
317
cg_enter_current_thread(const char * cgroup)318 int cg_enter_current_thread(const char *cgroup)
319 {
320 return cg_write(cgroup, "cgroup.threads", "0");
321 }
322
cg_run(const char * cgroup,int (* fn)(const char * cgroup,void * arg),void * arg)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
clone_into_cgroup(int cgroup_fd)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
clone_reap(pid_t pid,int options)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
dirfd_open_opath(const char * dir)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
clone_into_cgroup_run_nowait(const char * cgroup,int (* fn)(const char * cgroup,void * arg),void * arg)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
cg_run_nowait(const char * cgroup,int (* fn)(const char * cgroup,void * arg),void * arg)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
get_temp_fd(void)467 int get_temp_fd(void)
468 {
469 return open(".", O_TMPFILE | O_RDWR | O_EXCL);
470 }
471
alloc_pagecache(int fd,size_t size)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
alloc_anon(const char * cgroup,void * arg)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
is_swap_enabled(void)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
set_oom_adj_score(int pid,int score)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
proc_mount_contains(const char * option)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
proc_read_text(int pid,bool thread,const char * item,char * buf,size_t size)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
proc_read_strstr(int pid,bool thread,const char * item,const char * needle)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
clone_into_cgroup_run_wait(const char * cgroup)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
__prepare_for_wait(const char * cgroup,const char * filename)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
cg_prepare_for_wait(const char * cgroup)624 int cg_prepare_for_wait(const char *cgroup)
625 {
626 return __prepare_for_wait(cgroup, "cgroup.events");
627 }
628
memcg_prepare_for_wait(const char * cgroup)629 int memcg_prepare_for_wait(const char *cgroup)
630 {
631 return __prepare_for_wait(cgroup, "memory.events");
632 }
633
cg_wait_for(int fd)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