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 #include <sys/mman.h>
16
17 #include "pidfd.h"
18 #include "../kselftest.h"
19
20 struct error {
21 int code;
22 char msg[512];
23 };
24
25 static int error_set(struct error *err, int code, const char *fmt, ...)
26 {
27 va_list args;
28 int r;
29
30 if (code == PIDFD_PASS || !err || err->code != PIDFD_PASS)
31 return code;
32
33 err->code = code;
34 va_start(args, fmt);
35 r = vsnprintf(err->msg, sizeof(err->msg), fmt, args);
36 assert((size_t)r < sizeof(err->msg));
37 va_end(args);
38
39 return code;
40 }
41
42 static void error_report(struct error *err, const char *test_name)
43 {
44 switch (err->code) {
45 case PIDFD_ERROR:
46 ksft_exit_fail_msg("%s test: Fatal: %s\n", test_name, err->msg);
47 break;
48
49 case PIDFD_FAIL:
50 /* will be: not ok %d # error %s test: %s */
51 ksft_test_result_error("%s test: %s\n", test_name, err->msg);
52 break;
53
54 case PIDFD_SKIP:
55 /* will be: not ok %d # SKIP %s test: %s */
56 ksft_test_result_skip("%s test: %s\n", test_name, err->msg);
57 break;
58
59 case PIDFD_XFAIL:
60 ksft_test_result_pass("%s test: Expected failure: %s\n",
61 test_name, err->msg);
62 break;
63
64 case PIDFD_PASS:
65 ksft_test_result_pass("%s test: Passed\n", test_name);
66 break;
67
68 default:
69 ksft_exit_fail_msg("%s test: Unknown code: %d %s\n",
70 test_name, err->code, err->msg);
71 break;
72 }
73 }
74
75 static inline int error_check(struct error *err, const char *test_name)
76 {
77 /* In case of error we bail out and terminate the test program */
78 if (err->code == PIDFD_ERROR)
79 error_report(err, test_name);
80
81 return err->code;
82 }
83
84 #define CHILD_STACK_SIZE 8192
85
86 struct child {
87 char *stack;
88 pid_t pid;
89 int fd;
90 };
91
92 static struct child clone_newns(int (*fn)(void *), void *args,
93 struct error *err)
94 {
95 static int flags = CLONE_PIDFD | CLONE_NEWPID | CLONE_NEWNS | SIGCHLD;
96 struct child ret;
97
98 if (!(flags & CLONE_NEWUSER) && geteuid() != 0)
99 flags |= CLONE_NEWUSER;
100
101 ret.stack = mmap(NULL, CHILD_STACK_SIZE, PROT_READ | PROT_WRITE,
102 MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
103 if (ret.stack == MAP_FAILED) {
104 error_set(err, -1, "mmap of stack failed (errno %d)", errno);
105 return ret;
106 }
107
108 #ifdef __ia64__
109 ret.pid = __clone2(fn, ret.stack, CHILD_STACK_SIZE, flags, args, &ret.fd);
110 #else
111 ret.pid = clone(fn, ret.stack + CHILD_STACK_SIZE, flags, args, &ret.fd);
112 #endif
113
114 if (ret.pid < 0) {
115 error_set(err, PIDFD_ERROR, "clone failed (ret %d, errno %d)",
116 ret.fd, errno);
117 return ret;
118 }
119
120 ksft_print_msg("New child: %d, fd: %d\n", ret.pid, ret.fd);
121
122 return ret;
123 }
124
125 static inline void child_close(struct child *child)
126 {
127 close(child->fd);
128 }
129
130 static inline int child_join(struct child *child, struct error *err)
131 {
132 int r;
133
134 r = wait_for_pid(child->pid);
135 if (r < 0)
136 error_set(err, PIDFD_ERROR, "waitpid failed (ret %d, errno %d)",
137 r, errno);
138 else if (r > 0)
139 error_set(err, r, "child %d reported: %d", child->pid, r);
140
141 if (munmap(child->stack, CHILD_STACK_SIZE)) {
142 error_set(err, -1, "munmap of child stack failed (errno %d)", errno);
143 r = -1;
144 }
145
146 ksft_print_msg("waitpid WEXITSTATUS=%d\n", r);
147 return r;
148 }
149
150 static inline int child_join_close(struct child *child, struct error *err)
151 {
152 child_close(child);
153 return child_join(child, err);
154 }
155
156 static inline void trim_newline(char *str)
157 {
158 char *pos = strrchr(str, '\n');
159
160 if (pos)
161 *pos = '\0';
162 }
163
164 static int verify_fdinfo(int pidfd, struct error *err, const char *prefix,
165 size_t prefix_len, const char *expect, ...)
166 {
167 char buffer[512] = {0, };
168 char path[512] = {0, };
169 va_list args;
170 FILE *f;
171 char *line = NULL;
172 size_t n = 0;
173 int found = 0;
174 int r;
175
176 va_start(args, expect);
177 r = vsnprintf(buffer, sizeof(buffer), expect, args);
178 assert((size_t)r < sizeof(buffer));
179 va_end(args);
180
181 snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", pidfd);
182 f = fopen(path, "re");
183 if (!f)
184 return error_set(err, PIDFD_ERROR, "fdinfo open failed for %d",
185 pidfd);
186
187 while (getline(&line, &n, f) != -1) {
188 char *val;
189
190 if (strncmp(line, prefix, prefix_len))
191 continue;
192
193 found = 1;
194
195 val = line + prefix_len;
196 r = strcmp(val, buffer);
197 if (r != 0) {
198 trim_newline(line);
199 trim_newline(buffer);
200 error_set(err, PIDFD_FAIL, "%s '%s' != '%s'",
201 prefix, val, buffer);
202 }
203 break;
204 }
205
206 free(line);
207 fclose(f);
208
209 if (found == 0)
210 return error_set(err, PIDFD_FAIL, "%s not found for fd %d",
211 prefix, pidfd);
212
213 return PIDFD_PASS;
214 }
215
216 static int child_fdinfo_nspid_test(void *args)
217 {
218 struct error err;
219 int pidfd;
220 int r;
221
222 /* if we got no fd for the sibling, we are done */
223 if (!args)
224 return PIDFD_PASS;
225
226 /* verify that we can not resolve the pidfd for a process
227 * in a sibling pid namespace, i.e. a pid namespace it is
228 * not in our or a descended namespace
229 */
230 r = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
231 if (r < 0) {
232 ksft_print_msg("Failed to remount / private\n");
233 return PIDFD_ERROR;
234 }
235
236 (void)umount2("/proc", MNT_DETACH);
237 r = mount("proc", "/proc", "proc", 0, NULL);
238 if (r < 0) {
239 ksft_print_msg("Failed to remount /proc\n");
240 return PIDFD_ERROR;
241 }
242
243 pidfd = *(int *)args;
244 r = verify_fdinfo(pidfd, &err, "NSpid:", 6, "\t\n");
245
246 if (r != PIDFD_PASS)
247 ksft_print_msg("NSpid fdinfo check failed: %s\n", err.msg);
248
249 return r;
250 }
251
252 static void test_pidfd_fdinfo_nspid(void)
253 {
254 struct child a, b;
255 struct error err = {0, };
256 const char *test_name = "pidfd check for NSpid in fdinfo";
257
258 /* Create a new child in a new pid and mount namespace */
259 a = clone_newns(child_fdinfo_nspid_test, NULL, &err);
260 error_check(&err, test_name);
261
262 /* Pass the pidfd representing the first child to the
263 * second child, which will be in a sibling pid namespace,
264 * which means that the fdinfo NSpid entry for the pidfd
265 * should only contain ''.
266 */
267 b = clone_newns(child_fdinfo_nspid_test, &a.fd, &err);
268 error_check(&err, test_name);
269
270 /* The children will have pid 1 in the new pid namespace,
271 * so the line must be 'NSPid:\t<pid>\t1'.
272 */
273 verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t%d\t%d\n", a.pid, 1);
274 verify_fdinfo(b.fd, &err, "NSpid:", 6, "\t%d\t%d\n", b.pid, 1);
275
276 /* wait for the process, check the exit status and set
277 * 'err' accordingly, if it is not already set.
278 */
279 child_join_close(&a, &err);
280 child_join_close(&b, &err);
281
282 error_report(&err, test_name);
283 }
284
285 static void test_pidfd_dead_fdinfo(void)
286 {
287 struct child a;
288 struct error err = {0, };
289 const char *test_name = "pidfd check fdinfo for dead process";
290
291 /* Create a new child in a new pid and mount namespace */
292 a = clone_newns(child_fdinfo_nspid_test, NULL, &err);
293 error_check(&err, test_name);
294 child_join(&a, &err);
295
296 verify_fdinfo(a.fd, &err, "Pid:", 4, "\t-1\n");
297 verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t-1\n");
298 child_close(&a);
299 error_report(&err, test_name);
300 }
301
302 int main(int argc, char **argv)
303 {
304 ksft_print_header();
305 ksft_set_plan(2);
306
307 test_pidfd_fdinfo_nspid();
308 test_pidfd_dead_fdinfo();
309
310 ksft_exit_pass();
311 }
312
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