summaryrefslogtreecommitdiff
path: root/tools/testing/selftests/capabilities/test_execve.c
blob: 763f37fecfb86b5ba37ee4eae409712939d5edb8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
#define _GNU_SOURCE

#include <cap-ng.h>
#include <err.h>
#include <linux/capability.h>
#include <stdbool.h>
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <stdarg.h>
#include <sched.h>
#include <sys/mount.h>
#include <limits.h>
#include <libgen.h>
#include <malloc.h>
#include <sys/wait.h>
#include <sys/prctl.h>
#include <sys/stat.h>

#ifndef PR_CAP_AMBIENT
#define PR_CAP_AMBIENT			47
# define PR_CAP_AMBIENT_IS_SET		1
# define PR_CAP_AMBIENT_RAISE		2
# define PR_CAP_AMBIENT_LOWER		3
# define PR_CAP_AMBIENT_CLEAR_ALL	4
#endif

static int nerrs;

static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap)
{
	char buf[4096];
	int fd;
	ssize_t written;
	int buf_len;

	buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);
	if (buf_len < 0) {
		err(1, "vsnprintf failed");
	}
	if (buf_len >= sizeof(buf)) {
		errx(1, "vsnprintf output truncated");
	}

	fd = open(filename, O_WRONLY);
	if (fd < 0) {
		if ((errno == ENOENT) && enoent_ok)
			return;
		err(1, "open of %s failed", filename);
	}
	written = write(fd, buf, buf_len);
	if (written != buf_len) {
		if (written >= 0) {
			errx(1, "short write to %s", filename);
		} else {
			err(1, "write to %s failed", filename);
		}
	}
	if (close(fd) != 0) {
		err(1, "close of %s failed", filename);
	}
}

static void maybe_write_file(char *filename, char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	vmaybe_write_file(true, filename, fmt, ap);
	va_end(ap);
}

static void write_file(char *filename, char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	vmaybe_write_file(false, filename, fmt, ap);
	va_end(ap);
}

static bool create_and_enter_ns(uid_t inner_uid)
{
	uid_t outer_uid;
	gid_t outer_gid;
	int i;
	bool have_outer_privilege;

	outer_uid = getuid();
	outer_gid = getgid();

	/*
	 * TODO: If we're already root, we could skip creating the userns.
	 */

	if (unshare(CLONE_NEWNS) == 0) {
		printf("[NOTE]\tUsing global UIDs for tests\n");
		if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0)
			err(1, "PR_SET_KEEPCAPS");
		if (setresuid(inner_uid, inner_uid, -1) != 0)
			err(1, "setresuid");

		// Re-enable effective caps
		capng_get_caps_process();
		for (i = 0; i < CAP_LAST_CAP; i++)
			if (capng_have_capability(CAPNG_PERMITTED, i))
				capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, i);
		if (capng_apply(CAPNG_SELECT_CAPS) != 0)
			err(1, "capng_apply");

		have_outer_privilege = true;
	} else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
		printf("[NOTE]\tUsing a user namespace for tests\n");
		maybe_write_file("/proc/self/setgroups", "deny");
		write_file("/proc/self/uid_map", "%d %d 1", inner_uid, outer_uid);
		write_file("/proc/self/gid_map", "0 %d 1", outer_gid);

		have_outer_privilege = false;
	} else {
		errx(1, "must be root or be able to create a userns");
	}

	if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0)
		err(1, "remount everything private");

	return have_outer_privilege;
}

static void chdir_to_tmpfs(void)
{
	char cwd[PATH_MAX];
	if (getcwd(cwd, sizeof(cwd)) != cwd)
		err(1, "getcwd");

	if (mount("private_tmp", ".", "tmpfs", 0, "mode=0777") != 0)
		err(1, "mount private tmpfs");

	if (chdir(cwd) != 0)
		err(1, "chdir to private tmpfs");
}

static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
{
	int from = openat(fromfd, fromname, O_RDONLY);
	if (from == -1)
		err(1, "open copy source");

	int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);

	while (true) {
		char buf[4096];
		ssize_t sz = read(from, buf, sizeof(buf));
		if (sz == 0)
			break;
		if (sz < 0)
			err(1, "read");

		if (write(to, buf, sz) != sz)
			err(1, "write");	/* no short writes on tmpfs */
	}

	close(from);
	close(to);
}

static bool fork_wait(void)
{
	pid_t child = fork();
	if (child == 0) {
		nerrs = 0;
		return true;
	} else if (child > 0) {
		int status;
		if (waitpid(child, &status, 0) != child ||
		    !WIFEXITED(status)) {
			printf("[FAIL]\tChild died\n");
			nerrs++;
		} else if (WEXITSTATUS(status) != 0) {
			printf("[FAIL]\tChild failed\n");
			nerrs++;
		} else {
			printf("[OK]\tChild succeeded\n");
		}

		return false;
	} else {
		err(1, "fork");
	}
}

static void exec_other_validate_cap(const char *name,
				    bool eff, bool perm, bool inh, bool ambient)
{
	execl(name, name, (eff ? "1" : "0"),
	      (perm ? "1" : "0"), (inh ? "1" : "0"), (ambient ? "1" : "0"),
	      NULL);
	err(1, "execl");
}

static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient)
{
	exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient);
}

static int do_tests(int uid, const char *our_path)
{
	bool have_outer_privilege = create_and_enter_ns(uid);

	int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY);
	if (ourpath_fd == -1)
		err(1, "open '%s'", our_path);

	chdir_to_tmpfs();

	copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap");

	if (have_outer_privilege) {
		uid_t gid = getegid();

		copy_fromat_to(ourpath_fd, "validate_cap",
			       "validate_cap_suidroot");
		if (chown("validate_cap_suidroot", 0, -1) != 0)
			err(1, "chown");
		if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0)
			err(1, "chmod");

		copy_fromat_to(ourpath_fd, "validate_cap",
			       "validate_cap_suidnonroot");
		if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0)
			err(1, "chown");
		if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0)
			err(1, "chmod");

		copy_fromat_to(ourpath_fd, "validate_cap",
			       "validate_cap_sgidroot");
		if (chown("validate_cap_sgidroot", -1, 0) != 0)
			err(1, "chown");
		if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0)
			err(1, "chmod");

		copy_fromat_to(ourpath_fd, "validate_cap",
			       "validate_cap_sgidnonroot");
		if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0)
			err(1, "chown");
		if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0)
			err(1, "chmod");
	}

	capng_get_caps_process();

	/* Make sure that i starts out clear */
	capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
	if (capng_apply(CAPNG_SELECT_CAPS) != 0)
		err(1, "capng_apply");

	if (uid == 0) {
		printf("[RUN]\tRoot => ep\n");
		if (fork_wait())
			exec_validate_cap(true, true, false, false);
	} else {
		printf("[RUN]\tNon-root => no caps\n");
		if (fork_wait())
			exec_validate_cap(false, false, false, false);
	}

	printf("[OK]\tCheck cap_ambient manipulation rules\n");

	/* We should not be able to add ambient caps yet. */
	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) {
		if (errno == EINVAL)
			printf("[FAIL]\tPR_CAP_AMBIENT_RAISE isn't supported\n");
		else
			printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n");
		return 1;
	}
	printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n");

	capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW);
	capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW);
	capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW);
	if (capng_apply(CAPNG_SELECT_CAPS) != 0)
		err(1, "capng_apply");
	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) {
		printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n");
		return 1;
	}
	printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-permitted cap\n");

	capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
	if (capng_apply(CAPNG_SELECT_CAPS) != 0)
		err(1, "capng_apply");
	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
		printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have succeeded\n");
		return 1;
	}
	printf("[OK]\tPR_CAP_AMBIENT_RAISE worked\n");

	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) {
		printf("[FAIL]\tPR_CAP_AMBIENT_IS_SET is broken\n");
		return 1;
	}

	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0)
		err(1, "PR_CAP_AMBIENT_CLEAR_ALL");

	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
		printf("[FAIL]\tPR_CAP_AMBIENT_CLEAR_ALL didn't work\n");
		return 1;
	}

	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
		err(1, "PR_CAP_AMBIENT_RAISE");

	capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
	if (capng_apply(CAPNG_SELECT_CAPS) != 0)
		err(1, "capng_apply");

	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
		printf("[FAIL]\tDropping I should have dropped A\n");
		return 1;
	}

	printf("[OK]\tBasic manipulation appears to work\n");

	capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
	if (capng_apply(CAPNG_SELECT_CAPS) != 0)
		err(1, "capng_apply");
	if (uid == 0) {
		printf("[RUN]\tRoot +i => eip\n");
		if (fork_wait())
			exec_validate_cap(true, true, true, false);
	} else {
		printf("[RUN]\tNon-root +i => i\n");
		if (fork_wait())
			exec_validate_cap(false, false, true, false);
	}

	if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
		err(1, "PR_CAP_AMBIENT_RAISE");

	printf("[RUN]\tUID %d +ia => eipa\n", uid);
	if (fork_wait())
		exec_validate_cap(true, true, true, true);

	/* The remaining tests need real privilege */

	if (!have_outer_privilege) {
		printf("[SKIP]\tSUID/SGID tests (needs privilege)\n");
		goto done;
	}

	if (uid == 0) {
		printf("[RUN]\tRoot +ia, suidroot => eipa\n");
		if (fork_wait())
			exec_other_validate_cap("./validate_cap_suidroot",
						true, true, true, true);

		printf("[RUN]\tRoot +ia, suidnonroot => ip\n");
		if (fork_wait())
			exec_other_validate_cap("./validate_cap_suidnonroot",
						false, true, true, false);

		printf("[RUN]\tRoot +ia, sgidroot => eipa\n");
		if (fork_wait())
			exec_other_validate_cap("./validate_cap_sgidroot",
						true, true, true, true);

		if (fork_wait()) {
			printf("[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n");
			if (setresgid(1, 1, 1) != 0)
				err(1, "setresgid");
			exec_other_validate_cap("./validate_cap_sgidroot",
						true, true, true, false);
		}

		printf("[RUN]\tRoot +ia, sgidnonroot => eip\n");
		if (fork_wait())
			exec_other_validate_cap("./validate_cap_sgidnonroot",
						true, true, true, false);
	} else {
		printf("[RUN]\tNon-root +ia, sgidnonroot => i\n");
		exec_other_validate_cap("./validate_cap_sgidnonroot",
					false, false, true, false);

		if (fork_wait()) {
			printf("[RUN]\tNon-root +ia, sgidroot => i\n");
			if (setresgid(1, 1, 1) != 0)
				err(1, "setresgid");
			exec_other_validate_cap("./validate_cap_sgidroot",
						false, false, true, false);
		}
	}

done:
	return nerrs ? 1 : 0;
}

int main(int argc, char **argv)
{
	char *tmp1, *tmp2, *our_path;

	/* Find our path */
	tmp1 = strdup(argv[0]);
	if (!tmp1)
		err(1, "strdup");
	tmp2 = dirname(tmp1);
	our_path = strdup(tmp2);
	if (!our_path)
		err(1, "strdup");
	free(tmp1);

	if (fork_wait()) {
		printf("[RUN]\t+++ Tests with uid == 0 +++\n");
		return do_tests(0, our_path);
	}

	if (fork_wait()) {
		printf("[RUN]\t+++ Tests with uid != 0 +++\n");
		return do_tests(1, our_path);
	}

	return nerrs ? 1 : 0;
}