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
error_set(struct error * err,int code,const char * fmt,...)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
error_report(struct error * err,const char * test_name)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");
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
error_check(struct error * err,const char * test_name)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
clone_newns(int (* fn)(void *),void * args,struct error * err)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
child_close(struct child * child)125 static inline void child_close(struct child *child)
126 {
127 close(child->fd);
128 }
129
child_join(struct child * child,struct error * err)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 return r;
147 }
148
child_join_close(struct child * child,struct error * err)149 static inline int child_join_close(struct child *child, struct error *err)
150 {
151 child_close(child);
152 return child_join(child, err);
153 }
154
trim_newline(char * str)155 static inline void trim_newline(char *str)
156 {
157 char *pos = strrchr(str, '\n');
158
159 if (pos)
160 *pos = '\0';
161 }
162
verify_fdinfo(int pidfd,struct error * err,const char * prefix,size_t prefix_len,const char * expect,...)163 static int verify_fdinfo(int pidfd, struct error *err, const char *prefix,
164 size_t prefix_len, const char *expect, ...)
165 {
166 char buffer[512] = {0, };
167 char path[512] = {0, };
168 va_list args;
169 FILE *f;
170 char *line = NULL;
171 size_t n = 0;
172 int found = 0;
173 int r;
174
175 va_start(args, expect);
176 r = vsnprintf(buffer, sizeof(buffer), expect, args);
177 assert((size_t)r < sizeof(buffer));
178 va_end(args);
179
180 snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", pidfd);
181 f = fopen(path, "re");
182 if (!f)
183 return error_set(err, PIDFD_ERROR, "fdinfo open failed for %d",
184 pidfd);
185
186 while (getline(&line, &n, f) != -1) {
187 char *val;
188
189 if (strncmp(line, prefix, prefix_len))
190 continue;
191
192 found = 1;
193
194 val = line + prefix_len;
195 r = strcmp(val, buffer);
196 if (r != 0) {
197 trim_newline(line);
198 trim_newline(buffer);
199 error_set(err, PIDFD_FAIL, "%s '%s' != '%s'",
200 prefix, val, buffer);
201 }
202 break;
203 }
204
205 free(line);
206 fclose(f);
207
208 if (found == 0)
209 return error_set(err, PIDFD_FAIL, "%s not found for fd %d",
210 prefix, pidfd);
211
212 return PIDFD_PASS;
213 }
214
child_fdinfo_nspid_test(void * args)215 static int child_fdinfo_nspid_test(void *args)
216 {
217 struct error err;
218 int pidfd;
219 int r;
220
221 /* if we got no fd for the sibling, we are done */
222 if (!args)
223 return PIDFD_PASS;
224
225 /* verify that we can not resolve the pidfd for a process
226 * in a sibling pid namespace, i.e. a pid namespace it is
227 * not in our or a descended namespace
228 */
229 r = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
230 if (r < 0) {
231 ksft_print_msg("Failed to remount / private\n");
232 return PIDFD_ERROR;
233 }
234
235 (void)umount2("/proc", MNT_DETACH);
236 r = mount("proc", "/proc", "proc", 0, NULL);
237 if (r < 0) {
238 ksft_print_msg("Failed to remount /proc\n");
239 return PIDFD_ERROR;
240 }
241
242 pidfd = *(int *)args;
243 r = verify_fdinfo(pidfd, &err, "NSpid:", 6, "\t0\n");
244
245 if (r != PIDFD_PASS)
246 ksft_print_msg("NSpid fdinfo check failed: %s\n", err.msg);
247
248 return r;
249 }
250
test_pidfd_fdinfo_nspid(void)251 static void test_pidfd_fdinfo_nspid(void)
252 {
253 struct child a, b;
254 struct error err = {0, };
255 const char *test_name = "pidfd check for NSpid in fdinfo";
256
257 /* Create a new child in a new pid and mount namespace */
258 a = clone_newns(child_fdinfo_nspid_test, NULL, &err);
259 error_check(&err, test_name);
260
261 /* Pass the pidfd representing the first child to the
262 * second child, which will be in a sibling pid namespace,
263 * which means that the fdinfo NSpid entry for the pidfd
264 * should only contain '0'.
265 */
266 b = clone_newns(child_fdinfo_nspid_test, &a.fd, &err);
267 error_check(&err, test_name);
268
269 /* The children will have pid 1 in the new pid namespace,
270 * so the line must be 'NSPid:\t<pid>\t1'.
271 */
272 verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t%d\t%d\n", a.pid, 1);
273 verify_fdinfo(b.fd, &err, "NSpid:", 6, "\t%d\t%d\n", b.pid, 1);
274
275 /* wait for the process, check the exit status and set
276 * 'err' accordingly, if it is not already set.
277 */
278 child_join_close(&a, &err);
279 child_join_close(&b, &err);
280
281 error_report(&err, test_name);
282 }
283
test_pidfd_dead_fdinfo(void)284 static void test_pidfd_dead_fdinfo(void)
285 {
286 struct child a;
287 struct error err = {0, };
288 const char *test_name = "pidfd check fdinfo for dead process";
289
290 /* Create a new child in a new pid and mount namespace */
291 a = clone_newns(child_fdinfo_nspid_test, NULL, &err);
292 error_check(&err, test_name);
293 child_join(&a, &err);
294
295 verify_fdinfo(a.fd, &err, "Pid:", 4, "\t-1\n");
296 verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t-1\n");
297 child_close(&a);
298 error_report(&err, test_name);
299 }
300
main(int argc,char ** argv)301 int main(int argc, char **argv)
302 {
303 ksft_print_header();
304 ksft_set_plan(2);
305
306 test_pidfd_fdinfo_nspid();
307 test_pidfd_dead_fdinfo();
308
309 return ksft_exit_pass();
310 }
311