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