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 #ifndef PR_CAP_AMBIENT
24 #define PR_CAP_AMBIENT 47
25 # define PR_CAP_AMBIENT_IS_SET 1
26 # define PR_CAP_AMBIENT_RAISE 2
27 # define PR_CAP_AMBIENT_LOWER 3
28 # define PR_CAP_AMBIENT_CLEAR_ALL 4
29 #endif
30
31 static int nerrs;
32 static pid_t mpid; /* main() pid is used to avoid duplicate test counts */
33
vmaybe_write_file(bool enoent_ok,char * filename,char * fmt,va_list ap)34 static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap)
35 {
36 char buf[4096];
37 int fd;
38 ssize_t written;
39 int buf_len;
40
41 buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);
42 if (buf_len < 0)
43 ksft_exit_fail_msg("vsnprintf failed - %s\n", strerror(errno));
44
45 if (buf_len >= sizeof(buf))
46 ksft_exit_fail_msg("vsnprintf output truncated\n");
47
48
49 fd = open(filename, O_WRONLY);
50 if (fd < 0) {
51 if ((errno == ENOENT) && enoent_ok)
52 return;
53 ksft_exit_fail_msg("open of %s failed - %s\n",
54 filename, strerror(errno));
55 }
56 written = write(fd, buf, buf_len);
57 if (written != buf_len) {
58 if (written >= 0) {
59 ksft_exit_fail_msg("short write to %s\n", filename);
60 } else {
61 ksft_exit_fail_msg("write to %s failed - %s\n",
62 filename, strerror(errno));
63 }
64 }
65 if (close(fd) != 0) {
66 ksft_exit_fail_msg("close of %s failed - %s\n",
67 filename, strerror(errno));
68 }
69 }
70
maybe_write_file(char * filename,char * fmt,...)71 static void maybe_write_file(char *filename, char *fmt, ...)
72 {
73 va_list ap;
74
75 va_start(ap, fmt);
76 vmaybe_write_file(true, filename, fmt, ap);
77 va_end(ap);
78 }
79
write_file(char * filename,char * fmt,...)80 static void write_file(char *filename, char *fmt, ...)
81 {
82 va_list ap;
83
84 va_start(ap, fmt);
85 vmaybe_write_file(false, filename, fmt, ap);
86 va_end(ap);
87 }
88
create_and_enter_ns(uid_t inner_uid)89 static bool create_and_enter_ns(uid_t inner_uid)
90 {
91 uid_t outer_uid;
92 gid_t outer_gid;
93 int i;
94 bool have_outer_privilege;
95
96 outer_uid = getuid();
97 outer_gid = getgid();
98
99 /*
100 * TODO: If we're already root, we could skip creating the userns.
101 */
102
103 if (unshare(CLONE_NEWNS) == 0) {
104 ksft_print_msg("[NOTE]\tUsing global UIDs for tests\n");
105 if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0)
106 ksft_exit_fail_msg("PR_SET_KEEPCAPS - %s\n",
107 strerror(errno));
108 if (setresuid(inner_uid, inner_uid, -1) != 0)
109 ksft_exit_fail_msg("setresuid - %s\n", strerror(errno));
110
111 // Re-enable effective caps
112 capng_get_caps_process();
113 for (i = 0; i < CAP_LAST_CAP; i++)
114 if (capng_have_capability(CAPNG_PERMITTED, i))
115 capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, i);
116 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
117 ksft_exit_fail_msg(
118 "capng_apply - %s\n", strerror(errno));
119
120 have_outer_privilege = true;
121 } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
122 ksft_print_msg("[NOTE]\tUsing a user namespace for tests\n");
123 maybe_write_file("/proc/self/setgroups", "deny");
124 write_file("/proc/self/uid_map", "%d %d 1", inner_uid, outer_uid);
125 write_file("/proc/self/gid_map", "0 %d 1", outer_gid);
126
127 have_outer_privilege = false;
128 } else {
129 ksft_exit_skip("must be root or be able to create a userns\n");
130 }
131
132 if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0)
133 ksft_exit_fail_msg("remount everything private - %s\n",
134 strerror(errno));
135
136 return have_outer_privilege;
137 }
138
chdir_to_tmpfs(void)139 static void chdir_to_tmpfs(void)
140 {
141 char cwd[PATH_MAX];
142 if (getcwd(cwd, sizeof(cwd)) != cwd)
143 ksft_exit_fail_msg("getcwd - %s\n", strerror(errno));
144
145 if (mount("private_tmp", ".", "tmpfs", 0, "mode=0777") != 0)
146 ksft_exit_fail_msg("mount private tmpfs - %s\n",
147 strerror(errno));
148
149 if (chdir(cwd) != 0)
150 ksft_exit_fail_msg("chdir to private tmpfs - %s\n",
151 strerror(errno));
152 }
153
copy_fromat_to(int fromfd,const char * fromname,const char * toname)154 static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
155 {
156 int from = openat(fromfd, fromname, O_RDONLY);
157 if (from == -1)
158 ksft_exit_fail_msg("open copy source - %s\n", strerror(errno));
159
160 int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);
161
162 while (true) {
163 char buf[4096];
164 ssize_t sz = read(from, buf, sizeof(buf));
165 if (sz == 0)
166 break;
167 if (sz < 0)
168 ksft_exit_fail_msg("read - %s\n", strerror(errno));
169
170 if (write(to, buf, sz) != sz)
171 /* no short writes on tmpfs */
172 ksft_exit_fail_msg("write - %s\n", strerror(errno));
173 }
174
175 close(from);
176 close(to);
177 }
178
fork_wait(void)179 static bool fork_wait(void)
180 {
181 pid_t child = fork();
182 if (child == 0) {
183 nerrs = 0;
184 return true;
185 } else if (child > 0) {
186 int status;
187 if (waitpid(child, &status, 0) != child ||
188 !WIFEXITED(status)) {
189 ksft_print_msg("Child died\n");
190 nerrs++;
191 } else if (WEXITSTATUS(status) != 0) {
192 ksft_print_msg("Child failed\n");
193 nerrs++;
194 } else {
195 /* don't print this message for mpid */
196 if (getpid() != mpid)
197 ksft_test_result_pass("Passed\n");
198 }
199 return false;
200 } else {
201 ksft_exit_fail_msg("fork - %s\n", strerror(errno));
202 return false;
203 }
204 }
205
exec_other_validate_cap(const char * name,bool eff,bool perm,bool inh,bool ambient)206 static void exec_other_validate_cap(const char *name,
207 bool eff, bool perm, bool inh, bool ambient)
208 {
209 execl(name, name, (eff ? "1" : "0"),
210 (perm ? "1" : "0"), (inh ? "1" : "0"), (ambient ? "1" : "0"),
211 NULL);
212 ksft_exit_fail_msg("execl - %s\n", strerror(errno));
213 }
214
exec_validate_cap(bool eff,bool perm,bool inh,bool ambient)215 static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient)
216 {
217 exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient);
218 }
219
do_tests(int uid,const char * our_path)220 static int do_tests(int uid, const char *our_path)
221 {
222 bool have_outer_privilege = create_and_enter_ns(uid);
223
224 int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY);
225 if (ourpath_fd == -1)
226 ksft_exit_fail_msg("open '%s' - %s\n",
227 our_path, strerror(errno));
228
229 chdir_to_tmpfs();
230
231 copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap");
232
233 if (have_outer_privilege) {
234 uid_t gid = getegid();
235
236 copy_fromat_to(ourpath_fd, "validate_cap",
237 "validate_cap_suidroot");
238 if (chown("validate_cap_suidroot", 0, -1) != 0)
239 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
240 if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0)
241 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
242
243 copy_fromat_to(ourpath_fd, "validate_cap",
244 "validate_cap_suidnonroot");
245 if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0)
246 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
247 if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0)
248 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
249
250 copy_fromat_to(ourpath_fd, "validate_cap",
251 "validate_cap_sgidroot");
252 if (chown("validate_cap_sgidroot", -1, 0) != 0)
253 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
254 if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0)
255 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
256
257 copy_fromat_to(ourpath_fd, "validate_cap",
258 "validate_cap_sgidnonroot");
259 if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0)
260 ksft_exit_fail_msg("chown - %s\n", strerror(errno));
261 if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0)
262 ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
263 }
264
265 capng_get_caps_process();
266
267 /* Make sure that i starts out clear */
268 capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
269 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
270 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
271
272 if (uid == 0) {
273 ksft_print_msg("[RUN]\tRoot => ep\n");
274 if (fork_wait())
275 exec_validate_cap(true, true, false, false);
276 } else {
277 ksft_print_msg("[RUN]\tNon-root => no caps\n");
278 if (fork_wait())
279 exec_validate_cap(false, false, false, false);
280 }
281
282 ksft_print_msg("Check cap_ambient manipulation rules\n");
283
284 /* We should not be able to add ambient caps yet. */
285 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) {
286 if (errno == EINVAL)
287 ksft_test_result_fail(
288 "PR_CAP_AMBIENT_RAISE isn't supported\n");
289 else
290 ksft_test_result_fail(
291 "PR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n");
292 return 1;
293 }
294 ksft_test_result_pass(
295 "PR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n");
296
297 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW);
298 capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW);
299 capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW);
300 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
301 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
302 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) {
303 ksft_test_result_fail(
304 "PR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n");
305 return 1;
306 }
307 ksft_test_result_pass(
308 "PR_CAP_AMBIENT_RAISE failed on non-permitted cap\n");
309
310 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
311 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
312 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
313 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
314 ksft_test_result_fail(
315 "PR_CAP_AMBIENT_RAISE should have succeeded\n");
316 return 1;
317 }
318 ksft_test_result_pass("PR_CAP_AMBIENT_RAISE worked\n");
319
320 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) {
321 ksft_test_result_fail("PR_CAP_AMBIENT_IS_SET is broken\n");
322 return 1;
323 }
324
325 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0)
326 ksft_exit_fail_msg("PR_CAP_AMBIENT_CLEAR_ALL - %s\n",
327 strerror(errno));
328
329 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
330 ksft_test_result_fail(
331 "PR_CAP_AMBIENT_CLEAR_ALL didn't work\n");
332 return 1;
333 }
334
335 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
336 ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
337 strerror(errno));
338
339 capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
340 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
341 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
342
343 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
344 ksft_test_result_fail("Dropping I should have dropped A\n");
345 return 1;
346 }
347
348 ksft_test_result_pass("Basic manipulation appears to work\n");
349
350 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
351 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
352 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
353 if (uid == 0) {
354 ksft_print_msg("[RUN]\tRoot +i => eip\n");
355 if (fork_wait())
356 exec_validate_cap(true, true, true, false);
357 } else {
358 ksft_print_msg("[RUN]\tNon-root +i => i\n");
359 if (fork_wait())
360 exec_validate_cap(false, false, true, false);
361 }
362
363 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
364 ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
365 strerror(errno));
366
367 ksft_print_msg("[RUN]\tUID %d +ia => eipa\n", uid);
368 if (fork_wait())
369 exec_validate_cap(true, true, true, true);
370
371 /* The remaining tests need real privilege */
372
373 if (!have_outer_privilege) {
374 ksft_test_result_skip("SUID/SGID tests (needs privilege)\n");
375 goto done;
376 }
377
378 if (uid == 0) {
379 ksft_print_msg("[RUN]\tRoot +ia, suidroot => eipa\n");
380 if (fork_wait())
381 exec_other_validate_cap("./validate_cap_suidroot",
382 true, true, true, true);
383
384 ksft_print_msg("[RUN]\tRoot +ia, suidnonroot => ip\n");
385 if (fork_wait())
386 exec_other_validate_cap("./validate_cap_suidnonroot",
387 false, true, true, false);
388
389 ksft_print_msg("[RUN]\tRoot +ia, sgidroot => eipa\n");
390 if (fork_wait())
391 exec_other_validate_cap("./validate_cap_sgidroot",
392 true, true, true, true);
393
394 if (fork_wait()) {
395 ksft_print_msg(
396 "[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n");
397 if (setresgid(1, 1, 1) != 0)
398 ksft_exit_fail_msg("setresgid - %s\n",
399 strerror(errno));
400 exec_other_validate_cap("./validate_cap_sgidroot",
401 true, true, true, false);
402 }
403
404 ksft_print_msg("[RUN]\tRoot +ia, sgidnonroot => eip\n");
405 if (fork_wait())
406 exec_other_validate_cap("./validate_cap_sgidnonroot",
407 true, true, true, false);
408 } else {
409 ksft_print_msg("[RUN]\tNon-root +ia, sgidnonroot => i\n");
410 if (fork_wait())
411 exec_other_validate_cap("./validate_cap_sgidnonroot",
412 false, false, true, false);
413
414 if (fork_wait()) {
415 ksft_print_msg("[RUN]\tNon-root +ia, sgidroot => i\n");
416 if (setresgid(1, 1, 1) != 0)
417 ksft_exit_fail_msg("setresgid - %s\n",
418 strerror(errno));
419 exec_other_validate_cap("./validate_cap_sgidroot",
420 false, false, true, false);
421 }
422 }
423
424 done:
425 ksft_print_cnts();
426 return nerrs ? 1 : 0;
427 }
428
main(int argc,char ** argv)429 int main(int argc, char **argv)
430 {
431 char *tmp1, *tmp2, *our_path;
432
433 /* Find our path */
434 tmp1 = strdup(argv[0]);
435 if (!tmp1)
436 ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
437 tmp2 = dirname(tmp1);
438 our_path = strdup(tmp2);
439 if (!our_path)
440 ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
441 free(tmp1);
442
443 mpid = getpid();
444
445 if (fork_wait()) {
446 ksft_print_header();
447 ksft_set_plan(12);
448 ksft_print_msg("[RUN]\t+++ Tests with uid == 0 +++\n");
449 return do_tests(0, our_path);
450 }
451
452 ksft_print_msg("==================================================\n");
453
454 if (fork_wait()) {
455 ksft_print_header();
456 ksft_set_plan(9);
457 ksft_print_msg("[RUN]\t+++ Tests with uid != 0 +++\n");
458 return do_tests(1, our_path);
459 }
460
461 return nerrs ? 1 : 0;
462 }
463