1 /* Basic tests for Linux pidfd interfaces.
2 Copyright (C) 2022-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <support/capture_subprocess.h>
22 #include <support/check.h>
23 #include <support/process_state.h>
24 #include <support/support.h>
25 #include <support/xsignal.h>
26 #include <support/xunistd.h>
27 #include <support/xsocket.h>
28 #include <sys/pidfd.h>
29 #include <sys/wait.h>
30
31 #define REMOTE_PATH "/dev/null"
32
33 /* The pair of sockets used for coordination. The subprocess uses
34 sockets[1]. */
35 static int sockets[2];
36
37 static pid_t ppid;
38 static uid_t puid;
39
40 static void
41 sighandler (int sig)
42 {
43 }
44
45 static void
46 subprocess (void)
47 {
48 xsignal (SIGUSR1, sighandler);
49 xsignal (SIGUSR2, sighandler);
50
51 /* Check first pidfd_send_signal with default NULL siginfo_t argument. */
52 {
53 sigset_t set;
54 sigemptyset (&set);
55 sigaddset (&set, SIGUSR1);
56 siginfo_t info;
57 TEST_COMPARE (sigtimedwait (&set, &info, NULL), SIGUSR1);
58 TEST_COMPARE (info.si_signo, SIGUSR1);
59 TEST_COMPARE (info.si_errno, 0);
60 TEST_COMPARE (info.si_code, SI_USER);
61 TEST_COMPARE (info.si_pid, ppid);
62 TEST_COMPARE (info.si_uid, puid);
63 }
64
65 /* Check second pidfd_send_signal with crafted siginfo_t argument. */
66 {
67 sigset_t set;
68 sigemptyset (&set);
69 sigaddset (&set, SIGUSR2);
70 siginfo_t info;
71 TEST_COMPARE (sigtimedwait (&set, &info, NULL), SIGUSR2);
72 TEST_COMPARE (info.si_signo, SIGUSR2);
73 TEST_COMPARE (info.si_errno, EAGAIN);
74 TEST_COMPARE (info.si_code, -10);
75 TEST_COMPARE (info.si_pid, ppid);
76 TEST_COMPARE (info.si_uid, puid);
77 }
78
79 /* Send a local file descriptor value to check pidfd_getfd. */
80 int remote_fd = xopen (REMOTE_PATH, O_WRONLY | O_CLOEXEC, 0);
81 xsendto (sockets[1], &remote_fd, sizeof (remote_fd), 0, NULL, 0);
82
83 /* Wait for final pidfd_send_signal. */
84 pause ();
85
86 _exit (0);
87 }
88
89 static int
90 do_test (void)
91 {
92 {
93 /* The pidfd_getfd syscall was the last in the set of pidfd related
94 syscalls added to the kernel. Use pidfd_getfd to decide if this
95 kernel has pidfd support that we can test. */
96 int r = pidfd_getfd (0, 0, 1);
97 TEST_VERIFY_EXIT (r == -1);
98 if (errno == ENOSYS)
99 FAIL_UNSUPPORTED ("kernel does not support pidfd_getfd, skipping test");
100 }
101
102 ppid = getpid ();
103 puid = getuid ();
104
105 TEST_COMPARE (socketpair (AF_UNIX, SOCK_STREAM, 0, sockets), 0);
106
107 pid_t pid = xfork ();
108 if (pid == 0)
109 {
110 xclose (sockets[0]);
111 subprocess ();
112 }
113 xclose (sockets[1]);
114
115 TEST_COMPARE (pidfd_open (-1, 0), -1);
116 TEST_COMPARE (errno, EINVAL);
117
118 int pidfd = pidfd_open (pid, 0);
119 TEST_VERIFY (pidfd != -1);
120
121 /* Wait for first sigtimedwait. */
122 support_process_state_wait (pid, support_process_state_sleeping);
123 TEST_COMPARE (pidfd_send_signal (pidfd, SIGUSR1, NULL, 0), 0);
124
125 /* Wait for second sigtimedwait. */
126 support_process_state_wait (pid, support_process_state_sleeping);
127 {
128 siginfo_t info =
129 {
130 .si_signo = SIGUSR2,
131 .si_errno = EAGAIN,
132 .si_code = -10,
133 .si_pid = ppid,
134 .si_uid = puid
135 };
136 TEST_COMPARE (pidfd_send_signal (pidfd, SIGUSR2, &info, 0), 0);
137 }
138
139 /* Get remote file descriptor to check for pidfd_getfd. */
140 {
141 int remote_fd;
142 xrecvfrom (sockets[0], &remote_fd, sizeof (remote_fd), 0, NULL, 0);
143
144 int fd = pidfd_getfd (pidfd, remote_fd, 0);
145 /* pidfd_getfd may fail with EPERM if the process does not have
146 PTRACE_MODE_ATTACH_REALCREDS permissions. This means the call
147 may be denied if the process doesn't have CAP_SYS_PTRACE or
148 if a LSM security_ptrace_access_check denies access. */
149 if (fd == -1 && errno == EPERM)
150 {
151 TEST_COMPARE (pidfd_send_signal (pidfd, SIGKILL, NULL, 0), 0);
152 FAIL_UNSUPPORTED ("don't have permission to use pidfd_getfd on pidfd, "
153 "skipping test");
154 }
155 TEST_VERIFY (fd > 0);
156
157 char *path = xasprintf ("/proc/%d/fd/%d", pid, remote_fd);
158 char *resolved = xreadlink (path);
159 TEST_COMPARE_STRING (resolved, REMOTE_PATH);
160
161 int remote_fd_mode = fcntl (fd, F_GETFL);
162 TEST_VERIFY (remote_fd_mode != -1);
163 TEST_VERIFY (remote_fd_mode & O_WRONLY);
164
165 int remote_fd_flags = fcntl (fd, F_GETFD);
166 TEST_VERIFY (remote_fd_flags != -1);
167 TEST_VERIFY (remote_fd_flags & FD_CLOEXEC);
168 }
169
170 TEST_COMPARE (pidfd_send_signal (pidfd, SIGKILL, NULL, 0), 0);
171 {
172 siginfo_t info;
173 int r = waitid (P_PIDFD, pidfd, &info, WEXITED);
174 TEST_COMPARE (r, 0);
175 TEST_COMPARE (info.si_status, SIGKILL);
176 TEST_COMPARE (info.si_code, CLD_KILLED);
177 }
178
179 return 0;
180 }
181
182 #include <support/test-driver.c>