1 // SPDX-License-Identifier: GPL-2.0
2 #define _GNU_SOURCE
3
4 #include <cap-ng.h>
5 #include <linux/capability.h>
6 #include <stdbool.h>
7 #include <string.h>
8 #include <stdio.h>
9 #include <fcntl.h>
10 #include <errno.h>
11 #include <stdarg.h>
12 #include <sched.h>
13 #include <sys/mount.h>
14 #include <limits.h>
15 #include <libgen.h>
16 #include <malloc.h>
17 #include <sys/wait.h>
18 #include <sys/prctl.h>
19 #include <sys/stat.h>
20
21 #include "../kselftest.h"
22
23 static int nerrs;
24 static pid_t mpid; /* main() pid is used to avoid duplicate test counts */
25
26 static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap)
27 {
28 char buf[4096];
29 int fd;
30 ssize_t written;
31 int buf_len;
32
33 buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);
34 if (buf_len < 0)
35 ksft_exit_fail_msg("vsnprintf failed - %s\n", strerror(errno));
36
37 if (buf_len >= sizeof(buf))
38 ksft_exit_fail_msg("vsnprintf output truncated\n");
39
40
41 fd = open(filename, O_WRONLY);
42 if (fd < 0) {
43 if ((errno == ENOENT) && enoent_ok)
44 return;
45 ksft_exit_fail_msg("open of %s failed - %s\n",
46 filename, strerror(errno));
47 }
48 written = write(fd, buf, buf_len);
49 if (written != buf_len) {
50 if (written >= 0) {
51 ksft_exit_fail_msg("short write to %s\n", filename);
52 } else {
53 ksft_exit_fail_msg("write to %s failed - %s\n",
54 filename, strerror(errno));
55 }
56 }
57 if (close(fd) != 0) {
58 ksft_exit_fail_msg("close of %s failed - %s\n",
59 filename, strerror(errno));
60 }
61 }
62
63 static void maybe_write_file(char *filename, char *fmt, ...)
64 {
65 va_list ap;
66
67 va_start(ap, fmt);
68 vmaybe_write_file(true, filename, fmt, ap);
69 va_end(ap);
70 }
71
72 static void write_file(char *filename, char *fmt, ...)
73 {
74 va_list ap;
75
76 va_start(ap, fmt);
77 vmaybe_write_file(false, filename, fmt, ap);
78 va_end(ap);
79 }
80
81 static bool create_and_enter_ns(uid_t inner_uid)
82 {
83 uid_t outer_uid;
84 gid_t outer_gid;
85 int i, ret;
86 bool have_outer_privilege;
87
88 outer_uid = getuid();
89 outer_gid = getgid();
90
91 if (outer_uid == 0 && unshare(CLONE_NEWNS) == 0) {
92 ksft_print_msg("[NOTE]\tUsing global UIDs for tests\n");
93 if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0)
94 ksft_exit_fail_msg("PR_SET_KEEPCAPS - %s\n",
95 strerror(errno));
96 if (setresuid(inner_uid, inner_uid, -1) != 0)
97 ksft_exit_fail_msg("setresuid - %s\n", strerror(errno));
98
99 // Re-enable effective caps
100 ret = capng_get_caps_process();
101 if (ret == -1)
102 ksft_exit_fail_msg("capng_get_caps_process failed\n");
103
104 for (i = 0; i < CAP_LAST_CAP; i++)
105 if (capng_have_capability(CAPNG_PERMITTED, i))
106 capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, i);
107 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
108 ksft_exit_fail_msg(
109 "capng_apply - %s\n", strerror(errno));
110
111 have_outer_privilege = true;
112 } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
113 ksft_print_msg("[NOTE]\tUsing a user namespace for tests\n");
114 maybe_write_file("/proc/self/setgroups", "deny");
115 write_file("/proc/self/uid_map", "%d %d 1", inner_uid, outer_uid);
116 write_file("/proc/self/gid_map", "0 %d 1", outer_gid);
117
118 have_outer_privilege = false;
119 } else {
120 ksft_exit_skip("must be root or be able to create a userns\n");
121 }
122
123 if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0)
124 ksft_exit_fail_msg("remount everything private - %s\n",
125 strerror(errno));
126
127 return have_outer_privilege;
128 }
129
130 static void chdir_to_tmpfs(void)
131 {
132 char cwd[PATH_MAX];
133 if (getcwd(cwd, sizeof(cwd)) != cwd)
134 ksft_exit_fail_msg("getcwd - %s\n", strerror(errno));
135
136 if (mount("private_tmp", ".", "tmpfs", 0, "mode=0777") != 0)
137 ksft_exit_fail_msg("mount private tmpfs - %s\n",
138 strerror(errno));
139
140 if (chdir(cwd) != 0)
141 ksft_exit_fail_msg("chdir to private tmpfs - %s\n",
142 strerror(errno));
143 }
144
145 static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
146 {
147 int from = openat(fromfd, fromname, O_RDONLY);
148 if (from == -1)
149 ksft_exit_fail_msg("open copy source - %s\n", strerror(errno));
150
151 int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);
152
153 while (true) {
154 char buf[4096];
155 ssize_t sz = read(from, buf, sizeof(buf));
156 if (sz == 0)
157 break;
158 if (sz < 0)
159 ksft_exit_fail_msg("read - %s\n", strerror(errno));
160
161 if (write(to, buf, sz) != sz)
162 /* no short writes on tmpfs */
163 ksft_exit_fail_msg("write - %s\n", strerror(errno));
164 }
165
166 close(from);
167 close(to);
168 }
169
170 static bool fork_wait(void)
171 {
172 pid_t child = fork();
173 if (child == 0) {
174 nerrs = 0;
175 return true;
176 } else if (child > 0) {
177 int status;
178 if (waitpid(child, &status, 0) != child ||
179 !WIFEXITED(status)) {
180 ksft_print_msg("Child died\n");
181 nerrs++;
182 } else if (WEXITSTATUS(status) != 0) {
183 ksft_print_msg("Child failed\n");
184 nerrs++;
185 } else {
186 /* don't print this message for mpid */
187 if (getpid() != mpid)
188 ksft_test_result_pass("Passed\n");
189 }
190 return false;
191 } else {
192 ksft_exit_fail_msg("fork - %s\n", strerror(errno));
193 return false;
194 }
195 }
196
197 static void exec_other_validate_cap(const char *name,
198 bool eff, bool perm, bool inh, bool ambient)
199 {
200 execl(name, name, (eff ? "1" : ""),
201 (perm ? "1" : ""), (inh ? "1" : ""), (ambient ? "1" : ""),
202 NULL);
203 ksft_exit_fail_msg("execl - %s\n", strerror(errno));
204 }
205
206 static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient)
207 {
208 exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient);
209 }
210
211 static int do_tests(int uid, const char *our_path)
212 {
213 int ret;
214 bool have_outer_privilege = create_and_enter_ns(uid);
215
216 int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY);
217 if (ourpath_fd == -1)
218 ksft_exit_fail_msg("open '%s' - %s\n",
219 our_path, strerror(errno));
220
221 chdir_to_tmpfs();
222
223 copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap");
224
225 if (have_outer_privilege) {
226 uid_t gid = getegid();
227
228 copy_fromat_to(ourpath_fd, "validate_cap",
229 "validate_cap_suidroot");
230 if (chown("validate_cap_suidroot", 0, -1) != 0)
231 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
232 if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0)
233 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
234
235 copy_fromat_to(ourpath_fd, "validate_cap",
236 "validate_cap_suidnonroot");
237 if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0)
238 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
239 if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0)
240 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
241
242 copy_fromat_to(ourpath_fd, "validate_cap",
243 "validate_cap_sgidroot");
244 if (chown("validate_cap_sgidroot", -1, 0) != 0)
245 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
246 if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0)
247 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
248
249 copy_fromat_to(ourpath_fd, "validate_cap",
250 "validate_cap_sgidnonroot");
251 if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0)
252 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
253 if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0)
254 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
255 }
256
257 ret = capng_get_caps_process();
258 if (ret == -1)
259 ksft_exit_fail_msg("capng_get_caps_process failed\n");
260
261 /* Make sure that i starts out clear */
262 capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
263 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
264 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
265
266 if (uid == 0) {
267 ksft_print_msg("[RUN]\tRoot => ep\n");
268 if (fork_wait())
269 exec_validate_cap(true, true, false, false);
270 } else {
271 ksft_print_msg("[RUN]\tNon-root => no caps\n");
272 if (fork_wait())
273 exec_validate_cap(false, false, false, false);
274 }
275
276 ksft_print_msg("Check cap_ambient manipulation rules\n");
277
278 /* We should not be able to add ambient caps yet. */
279 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) {
280 if (errno == EINVAL)
281 ksft_test_result_fail(
282 "PR_CAP_AMBIENT_RAISE isn't supported\n");
283 else
284 ksft_test_result_fail(
285 "PR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n");
286 return 1;
287 }
288 ksft_test_result_pass(
289 "PR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n");
290
291 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW);
292 capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW);
293 capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW);
294 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
295 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
296 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) {
297 ksft_test_result_fail(
298 "PR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n");
299 return 1;
300 }
301 ksft_test_result_pass(
302 "PR_CAP_AMBIENT_RAISE failed on non-permitted cap\n");
303
304 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
305 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
306 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
307 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
308 ksft_test_result_fail(
309 "PR_CAP_AMBIENT_RAISE should have succeeded\n");
310 return 1;
311 }
312 ksft_test_result_pass("PR_CAP_AMBIENT_RAISE worked\n");
313
314 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) {
315 ksft_test_result_fail("PR_CAP_AMBIENT_IS_SET is broken\n");
316 return 1;
317 }
318
319 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0)
320 ksft_exit_fail_msg("PR_CAP_AMBIENT_CLEAR_ALL - %s\n",
321 strerror(errno));
322
323 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
324 ksft_test_result_fail(
325 "PR_CAP_AMBIENT_CLEAR_ALL didn't work\n");
326 return 1;
327 }
328
329 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
330 ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
331 strerror(errno));
332
333 capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
334 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
335 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
336
337 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
338 ksft_test_result_fail("Dropping I should have dropped A\n");
339 return 1;
340 }
341
342 ksft_test_result_pass("Basic manipulation appears to work\n");
343
344 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
345 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
346 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
347 if (uid == 0) {
348 ksft_print_msg("[RUN]\tRoot +i => eip\n");
349 if (fork_wait())
350 exec_validate_cap(true, true, true, false);
351 } else {
352 ksft_print_msg("[RUN]\tNon-root +i => i\n");
353 if (fork_wait())
354 exec_validate_cap(false, false, true, false);
355 }
356
357 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
358 ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
359 strerror(errno));
360
361 ksft_print_msg("[RUN]\tUID %d +ia => eipa\n", uid);
362 if (fork_wait())
363 exec_validate_cap(true, true, true, true);
364
365 /* The remaining tests need real privilege */
366
367 if (!have_outer_privilege) {
368 ksft_test_result_skip("SUID/SGID tests (needs privilege)\n");
369 goto done;
370 }
371
372 if (uid == 0) {
373 ksft_print_msg("[RUN]\tRoot +ia, suidroot => eipa\n");
374 if (fork_wait())
375 exec_other_validate_cap("./validate_cap_suidroot",
376 true, true, true, true);
377
378 ksft_print_msg("[RUN]\tRoot +ia, suidnonroot => ip\n");
379 if (fork_wait())
380 exec_other_validate_cap("./validate_cap_suidnonroot",
381 false, true, true, false);
382
383 ksft_print_msg("[RUN]\tRoot +ia, sgidroot => eipa\n");
384 if (fork_wait())
385 exec_other_validate_cap("./validate_cap_sgidroot",
386 true, true, true, true);
387
388 if (fork_wait()) {
389 ksft_print_msg(
390 "[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n");
391 if (setresgid(1, 1, 1) != 0)
392 ksft_exit_fail_msg("setresgid - %s\n",
393 strerror(errno));
394 exec_other_validate_cap("./validate_cap_sgidroot",
395 true, true, true, false);
396 }
397
398 ksft_print_msg("[RUN]\tRoot +ia, sgidnonroot => eip\n");
399 if (fork_wait())
400 exec_other_validate_cap("./validate_cap_sgidnonroot",
401 true, true, true, false);
402 } else {
403 ksft_print_msg("[RUN]\tNon-root +ia, sgidnonroot => i\n");
404 if (fork_wait())
405 exec_other_validate_cap("./validate_cap_sgidnonroot",
406 false, false, true, false);
407
408 if (fork_wait()) {
409 ksft_print_msg("[RUN]\tNon-root +ia, sgidroot => i\n");
410 if (setresgid(1, 1, 1) != 0)
411 ksft_exit_fail_msg("setresgid - %s\n",
412 strerror(errno));
413 exec_other_validate_cap("./validate_cap_sgidroot",
414 false, false, true, false);
415 }
416 }
417
418 done:
419 ksft_print_cnts();
420 return nerrs ? 1 : 0;
421 }
422
423 int main(int argc, char **argv)
424 {
425 char *tmp1, *tmp2, *our_path;
426
427 /* Find our path */
428 tmp1 = strdup(argv[0]);
429 if (!tmp1)
430 ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
431 tmp2 = dirname(tmp1);
432 our_path = strdup(tmp2);
433 if (!our_path)
434 ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
435 free(tmp1);
436
437 mpid = getpid();
438
439 if (fork_wait()) {
440 ksft_print_header();
441 ksft_set_plan(12);
442 ksft_print_msg("[RUN]\t+++ Tests with uid == 0 +++\n");
443 return do_tests(0, our_path);
444 }
445
446 ksft_print_msg("==================================================\n");
447
448 if (fork_wait()) {
449 ksft_print_header();
450 ksft_set_plan(9);
451 ksft_print_msg("[RUN]\t+++ Tests with uid != 0 +++\n");
452 return do_tests(1, our_path);
453 }
454
455 return nerrs ? 1 : 0;
456 }
457
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