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