1 /* SPDX-License-Identifier: GPL-2.0 */
2
3 #define _GNU_SOURCE
4 #include <errno.h>
5 #include <fcntl.h>
6 #include <linux/types.h>
7 #include <pthread.h>
8 #include <sched.h>
9 #include <signal.h>
10 #include <stdio.h>
11 #include <stdbool.h>
12 #include <stdlib.h>
13 #include <string.h>
14 #include <syscall.h>
15 #include <sys/epoll.h>
16 #include <sys/mman.h>
17 #include <sys/mount.h>
18 #include <sys/wait.h>
19 #include <time.h>
20 #include <unistd.h>
21
22 #include "pidfd.h"
23 #include "../kselftest.h"
24
25 #define str(s) _str(s)
26 #define _str(s) #s
27 #define CHILD_THREAD_MIN_WAIT 3 /* seconds */
28
29 #define MAX_EVENTS 5
30
31 static bool have_pidfd_send_signal;
32
33 static pid_t pidfd_clone(int flags, int *pidfd, int (*fn)(void *))
34 {
35 size_t stack_size = 1024;
36 char *stack[1024] = { 0 };
37
38 #ifdef __ia64__
39 return __clone2(fn, stack, stack_size, flags | SIGCHLD, NULL, pidfd);
40 #else
41 return clone(fn, stack + stack_size, flags | SIGCHLD, NULL, pidfd);
42 #endif
43 }
44
45 static int signal_received;
46
47 static void set_signal_received_on_sigusr1(int sig)
48 {
49 if (sig == SIGUSR1)
50 signal_received = 1;
51 }
52
53 /*
54 * Straightforward test to see whether pidfd_send_signal() works is to send
55 * a signal to ourself.
56 */
57 static int test_pidfd_send_signal_simple_success(void)
58 {
59 int pidfd, ret;
60 const char *test_name = "pidfd_send_signal send SIGUSR1";
61
62 if (!have_pidfd_send_signal) {
63 ksft_test_result_skip(
64 "%s test: pidfd_send_signal() syscall not supported\n",
65 test_name);
66 return 0;
67 }
68
69 pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC);
70 if (pidfd < 0)
71 ksft_exit_fail_msg(
72 "%s test: Failed to open process file descriptor\n",
73 test_name);
74
75 signal(SIGUSR1, set_signal_received_on_sigusr1);
76
77 ret = sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0);
78 close(pidfd);
79 if (ret < 0)
80 ksft_exit_fail_msg("%s test: Failed to send signal\n",
81 test_name);
82
83 if (signal_received != 1)
84 ksft_exit_fail_msg("%s test: Failed to receive signal\n",
85 test_name);
86
87 signal_received = 0;
88 ksft_test_result_pass("%s test: Sent signal\n", test_name);
89 return 0;
90 }
91
92 static int test_pidfd_send_signal_exited_fail(void)
93 {
94 int pidfd, ret, saved_errno;
95 char buf[256];
96 pid_t pid;
97 const char *test_name = "pidfd_send_signal signal exited process";
98
99 if (!have_pidfd_send_signal) {
100 ksft_test_result_skip(
101 "%s test: pidfd_send_signal() syscall not supported\n",
102 test_name);
103 return 0;
104 }
105
106 pid = fork();
107 if (pid < 0)
108 ksft_exit_fail_msg("%s test: Failed to create new process\n",
109 test_name);
110
111 if (pid == 0)
112 _exit(EXIT_SUCCESS);
113
114 snprintf(buf, sizeof(buf), "/proc/%d", pid);
115
116 pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
117
118 ret = wait_for_pid(pid);
119 ksft_print_msg("waitpid WEXITSTATUS=%d\n", ret);
120
121 if (pidfd < 0)
122 ksft_exit_fail_msg(
123 "%s test: Failed to open process file descriptor\n",
124 test_name);
125
126 ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
127 saved_errno = errno;
128 close(pidfd);
129 if (ret == 0)
130 ksft_exit_fail_msg(
131 "%s test: Managed to send signal to process even though it should have failed\n",
132 test_name);
133
134 if (saved_errno != ESRCH)
135 ksft_exit_fail_msg(
136 "%s test: Expected to receive ESRCH as errno value but received %d instead\n",
137 test_name, saved_errno);
138
139 ksft_test_result_pass("%s test: Failed to send signal as expected\n",
140 test_name);
141 return 0;
142 }
143
144 /*
145 * Maximum number of cycles we allow. This is equivalent to PID_MAX_DEFAULT.
146 * If users set a higher limit or we have cycled PIDFD_MAX_DEFAULT number of
147 * times then we skip the test to not go into an infinite loop or block for a
148 * long time.
149 */
150 #define PIDFD_MAX_DEFAULT 0x8000
151
152 static int test_pidfd_send_signal_recycled_pid_fail(void)
153 {
154 int i, ret;
155 pid_t pid1;
156 const char *test_name = "pidfd_send_signal signal recycled pid";
157
158 if (!have_pidfd_send_signal) {
159 ksft_test_result_skip(
160 "%s test: pidfd_send_signal() syscall not supported\n",
161 test_name);
162 return 0;
163 }
164
165 ret = unshare(CLONE_NEWPID);
166 if (ret < 0) {
167 if (errno == EPERM) {
168 ksft_test_result_skip("%s test: Unsharing pid namespace not permitted\n",
169 test_name);
170 return 0;
171 }
172 ksft_exit_fail_msg("%s test: Failed to unshare pid namespace\n",
173 test_name);
174 }
175
176 ret = unshare(CLONE_NEWNS);
177 if (ret < 0) {
178 if (errno == EPERM) {
179 ksft_test_result_skip("%s test: Unsharing mount namespace not permitted\n",
180 test_name);
181 return 0;
182 }
183 ksft_exit_fail_msg("%s test: Failed to unshare mount namespace\n",
184 test_name);
185 }
186
187 ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
188 if (ret < 0)
189 ksft_exit_fail_msg("%s test: Failed to remount / private\n",
190 test_name);
191
192 /* pid 1 in new pid namespace */
193 pid1 = fork();
194 if (pid1 < 0)
195 ksft_exit_fail_msg("%s test: Failed to create new process\n",
196 test_name);
197
198 if (pid1 == 0) {
199 char buf[256];
200 pid_t pid2;
201 int pidfd = -1;
202
203 (void)umount2("/proc", MNT_DETACH);
204 ret = mount("proc", "/proc", "proc", 0, NULL);
205 if (ret < 0)
206 _exit(PIDFD_ERROR);
207
208 /* grab pid PID_RECYCLE */
209 for (i = 0; i <= PIDFD_MAX_DEFAULT; i++) {
210 pid2 = fork();
211 if (pid2 < 0)
212 _exit(PIDFD_ERROR);
213
214 if (pid2 == 0)
215 _exit(PIDFD_PASS);
216
217 if (pid2 == PID_RECYCLE) {
218 snprintf(buf, sizeof(buf), "/proc/%d", pid2);
219 ksft_print_msg("pid to recycle is %d\n", pid2);
220 pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
221 }
222
223 if (wait_for_pid(pid2))
224 _exit(PIDFD_ERROR);
225
226 if (pid2 >= PID_RECYCLE)
227 break;
228 }
229
230 /*
231 * We want to be as predictable as we can so if we haven't been
232 * able to grab pid PID_RECYCLE skip the test.
233 */
234 if (pid2 != PID_RECYCLE) {
235 /* skip test */
236 close(pidfd);
237 _exit(PIDFD_SKIP);
238 }
239
240 if (pidfd < 0)
241 _exit(PIDFD_ERROR);
242
243 for (i = 0; i <= PIDFD_MAX_DEFAULT; i++) {
244 char c;
245 int pipe_fds[2];
246 pid_t recycled_pid;
247 int child_ret = PIDFD_PASS;
248
249 ret = pipe2(pipe_fds, O_CLOEXEC);
250 if (ret < 0)
251 _exit(PIDFD_ERROR);
252
253 recycled_pid = fork();
254 if (recycled_pid < 0)
255 _exit(PIDFD_ERROR);
256
257 if (recycled_pid == 0) {
258 close(pipe_fds[1]);
259 (void)read(pipe_fds[0], &c, 1);
260 close(pipe_fds[0]);
261
262 _exit(PIDFD_PASS);
263 }
264
265 /*
266 * Stop the child so we can inspect whether we have
267 * recycled pid PID_RECYCLE.
268 */
269 close(pipe_fds[0]);
270 ret = kill(recycled_pid, SIGSTOP);
271 close(pipe_fds[1]);
272 if (ret) {
273 (void)wait_for_pid(recycled_pid);
274 _exit(PIDFD_ERROR);
275 }
276
277 /*
278 * We have recycled the pid. Try to signal it. This
279 * needs to fail since this is a different process than
280 * the one the pidfd refers to.
281 */
282 if (recycled_pid == PID_RECYCLE) {
283 ret = sys_pidfd_send_signal(pidfd, SIGCONT,
284 NULL, 0);
285 if (ret && errno == ESRCH)
286 child_ret = PIDFD_XFAIL;
287 else
288 child_ret = PIDFD_FAIL;
289 }
290
291 /* let the process move on */
292 ret = kill(recycled_pid, SIGCONT);
293 if (ret)
294 (void)kill(recycled_pid, SIGKILL);
295
296 if (wait_for_pid(recycled_pid))
297 _exit(PIDFD_ERROR);
298
299 switch (child_ret) {
300 case PIDFD_FAIL:
301 /* fallthrough */
302 case PIDFD_XFAIL:
303 _exit(child_ret);
304 case PIDFD_PASS:
305 break;
306 default:
307 /* not reached */
308 _exit(PIDFD_ERROR);
309 }
310
311 /*
312 * If the user set a custom pid_max limit we could be
313 * in the millions.
314 * Skip the test in this case.
315 */
316 if (recycled_pid > PIDFD_MAX_DEFAULT)
317 _exit(PIDFD_SKIP);
318 }
319
320 /* failed to recycle pid */
321 _exit(PIDFD_SKIP);
322 }
323
324 ret = wait_for_pid(pid1);
325 switch (ret) {
326 case PIDFD_FAIL:
327 ksft_exit_fail_msg(
328 "%s test: Managed to signal recycled pid %d\n",
329 test_name, PID_RECYCLE);
330 case PIDFD_PASS:
331 ksft_exit_fail_msg("%s test: Failed to recycle pid %d\n",
332 test_name, PID_RECYCLE);
333 case PIDFD_SKIP:
334 ksft_test_result_skip("%s test: Skipping test\n", test_name);
335 ret = 0;
336 break;
337 case PIDFD_XFAIL:
338 ksft_test_result_pass(
339 "%s test: Failed to signal recycled pid as expected\n",
340 test_name);
341 ret = 0;
342 break;
343 default /* PIDFD_ERROR */:
344 ksft_exit_fail_msg("%s test: Error while running tests\n",
345 test_name);
346 }
347
348 return ret;
349 }
350
351 static int test_pidfd_send_signal_syscall_support(void)
352 {
353 int pidfd, ret;
354 const char *test_name = "pidfd_send_signal check for support";
355
356 pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC);
357 if (pidfd < 0)
358 ksft_exit_fail_msg(
359 "%s test: Failed to open process file descriptor\n",
360 test_name);
361
362 ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
363 if (ret < 0) {
364 if (errno == ENOSYS) {
365 ksft_test_result_skip(
366 "%s test: pidfd_send_signal() syscall not supported\n",
367 test_name);
368 return 0;
369 }
370 ksft_exit_fail_msg("%s test: Failed to send signal\n",
371 test_name);
372 }
373
374 have_pidfd_send_signal = true;
375 close(pidfd);
376 ksft_test_result_pass(
377 "%s test: pidfd_send_signal() syscall is supported. Tests can be executed\n",
378 test_name);
379 return 0;
380 }
381
382 static void *test_pidfd_poll_exec_thread(void *priv)
383 {
384 ksft_print_msg("Child Thread: starting. pid %d tid %ld ; and sleeping\n",
385 getpid(), syscall(SYS_gettid));
386 ksft_print_msg("Child Thread: doing exec of sleep\n");
387
388 execl("/bin/sleep", "sleep", str(CHILD_THREAD_MIN_WAIT), (char *)NULL);
389
390 ksft_print_msg("Child Thread: DONE. pid %d tid %ld\n",
391 getpid(), syscall(SYS_gettid));
392 return NULL;
393 }
394
395 static void poll_pidfd(const char *test_name, int pidfd)
396 {
397 int c;
398 int epoll_fd = epoll_create1(EPOLL_CLOEXEC);
399 struct epoll_event event, events[MAX_EVENTS];
400
401 if (epoll_fd == -1)
402 ksft_exit_fail_msg("%s test: Failed to create epoll file descriptor "
403 "(errno %d)\n",
404 test_name, errno);
405
406 event.events = EPOLLIN;
407 event.data.fd = pidfd;
408
409 if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, pidfd, &event)) {
410 ksft_exit_fail_msg("%s test: Failed to add epoll file descriptor "
411 "(errno %d)\n",
412 test_name, errno);
413 }
414
415 c = epoll_wait(epoll_fd, events, MAX_EVENTS, 5000);
416 if (c != 1 || !(events[0].events & EPOLLIN))
417 ksft_exit_fail_msg("%s test: Unexpected epoll_wait result (c=%d, events=%x) "
418 "(errno %d)\n",
419 test_name, c, events[0].events, errno);
420
421 close(epoll_fd);
422 return;
423
424 }
425
426 static int child_poll_exec_test(void *args)
427 {
428 pthread_t t1;
429
430 ksft_print_msg("Child (pidfd): starting. pid %d tid %ld\n", getpid(),
431 syscall(SYS_gettid));
432 pthread_create(&t1, NULL, test_pidfd_poll_exec_thread, NULL);
433 /*
434 * Exec in the non-leader thread will destroy the leader immediately.
435 * If the wait in the parent returns too soon, the test fails.
436 */
437 while (1)
438 sleep(1);
439
440 return 0;
441 }
442
443 static void test_pidfd_poll_exec(int use_waitpid)
444 {
445 int pid, pidfd = 0;
446 int status, ret;
447 time_t prog_start = time(NULL);
448 const char *test_name = "pidfd_poll check for premature notification on child thread exec";
449
450 ksft_print_msg("Parent: pid: %d\n", getpid());
451 pid = pidfd_clone(CLONE_PIDFD, &pidfd, child_poll_exec_test);
452 if (pid < 0)
453 ksft_exit_fail_msg("%s test: pidfd_clone failed (ret %d, errno %d)\n",
454 test_name, pid, errno);
455
456 ksft_print_msg("Parent: Waiting for Child (%d) to complete.\n", pid);
457
458 if (use_waitpid) {
459 ret = waitpid(pid, &status, 0);
460 if (ret == -1)
461 ksft_print_msg("Parent: error\n");
462
463 if (ret == pid)
464 ksft_print_msg("Parent: Child process waited for.\n");
465 } else {
466 poll_pidfd(test_name, pidfd);
467 }
468
469 time_t prog_time = time(NULL) - prog_start;
470
471 ksft_print_msg("Time waited for child: %lu\n", prog_time);
472
473 close(pidfd);
474
475 if (prog_time < CHILD_THREAD_MIN_WAIT || prog_time > CHILD_THREAD_MIN_WAIT + 2)
476 ksft_exit_fail_msg("%s test: Failed\n", test_name);
477 else
478 ksft_test_result_pass("%s test: Passed\n", test_name);
479 }
480
481 static void *test_pidfd_poll_leader_exit_thread(void *priv)
482 {
483 ksft_print_msg("Child Thread: starting. pid %d tid %ld ; and sleeping\n",
484 getpid(), syscall(SYS_gettid));
485 sleep(CHILD_THREAD_MIN_WAIT);
486 ksft_print_msg("Child Thread: DONE. pid %d tid %ld\n", getpid(), syscall(SYS_gettid));
487 return NULL;
488 }
489
490 static time_t *child_exit_secs;
491 static int child_poll_leader_exit_test(void *args)
492 {
493 pthread_t t1, t2;
494
495 ksft_print_msg("Child: starting. pid %d tid %ld\n", getpid(), syscall(SYS_gettid));
496 pthread_create(&t1, NULL, test_pidfd_poll_leader_exit_thread, NULL);
497 pthread_create(&t2, NULL, test_pidfd_poll_leader_exit_thread, NULL);
498
499 /*
500 * glibc exit calls exit_group syscall, so explicity call exit only
501 * so that only the group leader exits, leaving the threads alone.
502 */
503 *child_exit_secs = time(NULL);
504 syscall(SYS_exit, 0);
505 /* Never reached, but appeases compiler thinking we should return. */
506 exit(0);
507 }
508
509 static void test_pidfd_poll_leader_exit(int use_waitpid)
510 {
511 int pid, pidfd = 0;
512 int status, ret = 0;
513 const char *test_name = "pidfd_poll check for premature notification on non-empty"
514 "group leader exit";
515
516 child_exit_secs = mmap(NULL, sizeof *child_exit_secs, PROT_READ | PROT_WRITE,
517 MAP_SHARED | MAP_ANONYMOUS, -1, 0);
518
519 if (child_exit_secs == MAP_FAILED)
520 ksft_exit_fail_msg("%s test: mmap failed (errno %d)\n",
521 test_name, errno);
522
523 ksft_print_msg("Parent: pid: %d\n", getpid());
524 pid = pidfd_clone(CLONE_PIDFD, &pidfd, child_poll_leader_exit_test);
525 if (pid < 0)
526 ksft_exit_fail_msg("%s test: pidfd_clone failed (ret %d, errno %d)\n",
527 test_name, pid, errno);
528
529 ksft_print_msg("Parent: Waiting for Child (%d) to complete.\n", pid);
530
531 if (use_waitpid) {
532 ret = waitpid(pid, &status, 0);
533 if (ret == -1)
534 ksft_print_msg("Parent: error\n");
535 } else {
536 /*
537 * This sleep tests for the case where if the child exits, and is in
538 * EXIT_ZOMBIE, but the thread group leader is non-empty, then the poll
539 * doesn't prematurely return even though there are active threads
540 */
541 sleep(1);
542 poll_pidfd(test_name, pidfd);
543 }
544
545 if (ret == pid)
546 ksft_print_msg("Parent: Child process waited for.\n");
547
548 time_t since_child_exit = time(NULL) - *child_exit_secs;
549
550 ksft_print_msg("Time since child exit: %lu\n", since_child_exit);
551
552 close(pidfd);
553
554 if (since_child_exit < CHILD_THREAD_MIN_WAIT ||
555 since_child_exit > CHILD_THREAD_MIN_WAIT + 2)
556 ksft_exit_fail_msg("%s test: Failed\n", test_name);
557 else
558 ksft_test_result_pass("%s test: Passed\n", test_name);
559 }
560
561 int main(int argc, char **argv)
562 {
563 ksft_print_header();
564 ksft_set_plan(8);
565
566 test_pidfd_poll_exec(0);
567 test_pidfd_poll_exec(1);
568 test_pidfd_poll_leader_exit(0);
569 test_pidfd_poll_leader_exit(1);
570 test_pidfd_send_signal_syscall_support();
571 test_pidfd_send_signal_simple_success();
572 test_pidfd_send_signal_exited_fail();
573 test_pidfd_send_signal_recycled_pid_fail();
574
575 ksft_exit_pass();
576 }
577
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