1 // SPDX-License-Identifier: GPL-2.0
2
3 #define _GNU_SOURCE
4 #include <assert.h>
5 #include <errno.h>
6 #include <fcntl.h>
7 #include <linux/types.h>
8 #include <sched.h>
9 #include <signal.h>
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <string.h>
13 #include <syscall.h>
14 #include <sys/wait.h>
15
16 #include "pidfd.h"
17 #include "../kselftest.h"
18
19 struct error {
20 int code;
21 char msg[512];
22 };
23
error_set(struct error * err,int code,const char * fmt,...)24 static int error_set(struct error *err, int code, const char *fmt, ...)
25 {
26 va_list args;
27 int r;
28
29 if (code == PIDFD_PASS || !err || err->code != PIDFD_PASS)
30 return code;
31
32 err->code = code;
33 va_start(args, fmt);
34 r = vsnprintf(err->msg, sizeof(err->msg), fmt, args);
35 assert((size_t)r < sizeof(err->msg));
36 va_end(args);
37
38 return code;
39 }
40
error_report(struct error * err,const char * test_name)41 static void error_report(struct error *err, const char *test_name)
42 {
43 switch (err->code) {
44 case PIDFD_ERROR:
45 ksft_exit_fail_msg("%s test: Fatal: %s\n", test_name, err->msg);
46 break;
47
48 case PIDFD_FAIL:
49 /* will be: not ok %d # error %s test: %s */
50 ksft_test_result_error("%s test: %s\n", test_name, err->msg);
51 break;
52
53 case PIDFD_SKIP:
54 /* will be: not ok %d # SKIP %s test: %s */
55 ksft_test_result_skip("%s test: %s\n", test_name, err->msg);
56 break;
57
58 case PIDFD_XFAIL:
59 ksft_test_result_pass("%s test: Expected failure: %s\n",
60 test_name, err->msg);
61 break;
62
63 case PIDFD_PASS:
64 ksft_test_result_pass("%s test: Passed\n");
65 break;
66
67 default:
68 ksft_exit_fail_msg("%s test: Unknown code: %d %s\n",
69 test_name, err->code, err->msg);
70 break;
71 }
72 }
73
error_check(struct error * err,const char * test_name)74 static inline int error_check(struct error *err, const char *test_name)
75 {
76 /* In case of error we bail out and terminate the test program */
77 if (err->code == PIDFD_ERROR)
78 error_report(err, test_name);
79
80 return err->code;
81 }
82
83 struct child {
84 pid_t pid;
85 int fd;
86 };
87
clone_newns(int (* fn)(void *),void * args,struct error * err)88 static struct child clone_newns(int (*fn)(void *), void *args,
89 struct error *err)
90 {
91 static int flags = CLONE_PIDFD | CLONE_NEWPID | CLONE_NEWNS | SIGCHLD;
92 size_t stack_size = 1024;
93 char *stack[1024] = { 0 };
94 struct child ret;
95
96 if (!(flags & CLONE_NEWUSER) && geteuid() != 0)
97 flags |= CLONE_NEWUSER;
98
99 #ifdef __ia64__
100 ret.pid = __clone2(fn, stack, stack_size, flags, args, &ret.fd);
101 #else
102 ret.pid = clone(fn, stack + stack_size, flags, args, &ret.fd);
103 #endif
104
105 if (ret.pid < 0) {
106 error_set(err, PIDFD_ERROR, "clone failed (ret %d, errno %d)",
107 ret.fd, errno);
108 return ret;
109 }
110
111 ksft_print_msg("New child: %d, fd: %d\n", ret.pid, ret.fd);
112
113 return ret;
114 }
115
child_close(struct child * child)116 static inline void child_close(struct child *child)
117 {
118 close(child->fd);
119 }
120
child_join(struct child * child,struct error * err)121 static inline int child_join(struct child *child, struct error *err)
122 {
123 int r;
124
125 r = wait_for_pid(child->pid);
126 if (r < 0)
127 error_set(err, PIDFD_ERROR, "waitpid failed (ret %d, errno %d)",
128 r, errno);
129 else if (r > 0)
130 error_set(err, r, "child %d reported: %d", child->pid, r);
131
132 return r;
133 }
134
child_join_close(struct child * child,struct error * err)135 static inline int child_join_close(struct child *child, struct error *err)
136 {
137 child_close(child);
138 return child_join(child, err);
139 }
140
trim_newline(char * str)141 static inline void trim_newline(char *str)
142 {
143 char *pos = strrchr(str, '\n');
144
145 if (pos)
146 *pos = '\0';
147 }
148
verify_fdinfo(int pidfd,struct error * err,const char * prefix,size_t prefix_len,const char * expect,...)149 static int verify_fdinfo(int pidfd, struct error *err, const char *prefix,
150 size_t prefix_len, const char *expect, ...)
151 {
152 char buffer[512] = {0, };
153 char path[512] = {0, };
154 va_list args;
155 FILE *f;
156 char *line = NULL;
157 size_t n = 0;
158 int found = 0;
159 int r;
160
161 va_start(args, expect);
162 r = vsnprintf(buffer, sizeof(buffer), expect, args);
163 assert((size_t)r < sizeof(buffer));
164 va_end(args);
165
166 snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", pidfd);
167 f = fopen(path, "re");
168 if (!f)
169 return error_set(err, PIDFD_ERROR, "fdinfo open failed for %d",
170 pidfd);
171
172 while (getline(&line, &n, f) != -1) {
173 char *val;
174
175 if (strncmp(line, prefix, prefix_len))
176 continue;
177
178 found = 1;
179
180 val = line + prefix_len;
181 r = strcmp(val, buffer);
182 if (r != 0) {
183 trim_newline(line);
184 trim_newline(buffer);
185 error_set(err, PIDFD_FAIL, "%s '%s' != '%s'",
186 prefix, val, buffer);
187 }
188 break;
189 }
190
191 free(line);
192 fclose(f);
193
194 if (found == 0)
195 return error_set(err, PIDFD_FAIL, "%s not found for fd %d",
196 prefix, pidfd);
197
198 return PIDFD_PASS;
199 }
200
child_fdinfo_nspid_test(void * args)201 static int child_fdinfo_nspid_test(void *args)
202 {
203 struct error err;
204 int pidfd;
205 int r;
206
207 /* if we got no fd for the sibling, we are done */
208 if (!args)
209 return PIDFD_PASS;
210
211 /* verify that we can not resolve the pidfd for a process
212 * in a sibling pid namespace, i.e. a pid namespace it is
213 * not in our or a descended namespace
214 */
215 r = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
216 if (r < 0) {
217 ksft_print_msg("Failed to remount / private\n");
218 return PIDFD_ERROR;
219 }
220
221 (void)umount2("/proc", MNT_DETACH);
222 r = mount("proc", "/proc", "proc", 0, NULL);
223 if (r < 0) {
224 ksft_print_msg("Failed to remount /proc\n");
225 return PIDFD_ERROR;
226 }
227
228 pidfd = *(int *)args;
229 r = verify_fdinfo(pidfd, &err, "NSpid:", 6, "\t0\n");
230
231 if (r != PIDFD_PASS)
232 ksft_print_msg("NSpid fdinfo check failed: %s\n", err.msg);
233
234 return r;
235 }
236
test_pidfd_fdinfo_nspid(void)237 static void test_pidfd_fdinfo_nspid(void)
238 {
239 struct child a, b;
240 struct error err = {0, };
241 const char *test_name = "pidfd check for NSpid in fdinfo";
242
243 /* Create a new child in a new pid and mount namespace */
244 a = clone_newns(child_fdinfo_nspid_test, NULL, &err);
245 error_check(&err, test_name);
246
247 /* Pass the pidfd representing the first child to the
248 * second child, which will be in a sibling pid namespace,
249 * which means that the fdinfo NSpid entry for the pidfd
250 * should only contain '0'.
251 */
252 b = clone_newns(child_fdinfo_nspid_test, &a.fd, &err);
253 error_check(&err, test_name);
254
255 /* The children will have pid 1 in the new pid namespace,
256 * so the line must be 'NSPid:\t<pid>\t1'.
257 */
258 verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t%d\t%d\n", a.pid, 1);
259 verify_fdinfo(b.fd, &err, "NSpid:", 6, "\t%d\t%d\n", b.pid, 1);
260
261 /* wait for the process, check the exit status and set
262 * 'err' accordingly, if it is not already set.
263 */
264 child_join_close(&a, &err);
265 child_join_close(&b, &err);
266
267 error_report(&err, test_name);
268 }
269
test_pidfd_dead_fdinfo(void)270 static void test_pidfd_dead_fdinfo(void)
271 {
272 struct child a;
273 struct error err = {0, };
274 const char *test_name = "pidfd check fdinfo for dead process";
275
276 /* Create a new child in a new pid and mount namespace */
277 a = clone_newns(child_fdinfo_nspid_test, NULL, &err);
278 error_check(&err, test_name);
279 child_join(&a, &err);
280
281 verify_fdinfo(a.fd, &err, "Pid:", 4, "\t-1\n");
282 verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t-1\n");
283 child_close(&a);
284 error_report(&err, test_name);
285 }
286
main(int argc,char ** argv)287 int main(int argc, char **argv)
288 {
289 ksft_print_header();
290 ksft_set_plan(2);
291
292 test_pidfd_fdinfo_nspid();
293 test_pidfd_dead_fdinfo();
294
295 return ksft_exit_pass();
296 }
297
