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 29 static int nerrs; 30 31 static 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 65 static 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 74 static 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 83 static 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 * TODO: If we're already root, we could skip creating the userns. 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 // Re-enable effective caps 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 } 129 130 static 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 if (umount2(".", MNT_DETACH) != 0) 143 err(1, "detach private tmpfs"); 144 } 145 146 static void copy_fromat_to(int fromfd, const char *fromname, const char *toname) 147 { 148 int from = openat(fromfd, fromname, O_RDONLY); 149 if (from == -1) 150 err(1, "open copy source"); 151 152 int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700); 153 154 while (true) { 155 char buf[4096]; 156 ssize_t sz = read(from, buf, sizeof(buf)); 157 if (sz == 0) 158 break; 159 if (sz < 0) 160 err(1, "read"); 161 162 if (write(to, buf, sz) != sz) 163 err(1, "write"); /* no short writes on tmpfs */ 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 printf("[FAIL]\tChild died\n"); 181 nerrs++; 182 } else if (WEXITSTATUS(status) != 0) { 183 printf("[FAIL]\tChild failed\n"); 184 nerrs++; 185 } else { 186 printf("[OK]\tChild succeeded\n"); 187 } 188 189 return false; 190 } else { 191 err(1, "fork"); 192 } 193 } 194 195 static void exec_other_validate_cap(const char *name, 196 bool eff, bool perm, bool inh, bool ambient) 197 { 198 execl(name, name, (eff ? "1" : "0"), 199 (perm ? "1" : "0"), (inh ? "1" : "0"), (ambient ? "1" : "0"), 200 NULL); 201 err(1, "execl"); 202 } 203 204 static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient) 205 { 206 exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient); 207 } 208 209 static int do_tests(int uid, const char *our_path) 210 { 211 bool have_outer_privilege = create_and_enter_ns(uid); 212 213 int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY); 214 if (ourpath_fd == -1) 215 err(1, "open '%s'", our_path); 216 217 chdir_to_tmpfs(); 218 219 copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap"); 220 221 if (have_outer_privilege) { 222 uid_t gid = getegid(); 223 224 copy_fromat_to(ourpath_fd, "validate_cap", 225 "validate_cap_suidroot"); 226 if (chown("validate_cap_suidroot", 0, -1) != 0) 227 err(1, "chown"); 228 if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0) 229 err(1, "chmod"); 230 231 copy_fromat_to(ourpath_fd, "validate_cap", 232 "validate_cap_suidnonroot"); 233 if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0) 234 err(1, "chown"); 235 if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0) 236 err(1, "chmod"); 237 238 copy_fromat_to(ourpath_fd, "validate_cap", 239 "validate_cap_sgidroot"); 240 if (chown("validate_cap_sgidroot", -1, 0) != 0) 241 err(1, "chown"); 242 if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0) 243 err(1, "chmod"); 244 245 copy_fromat_to(ourpath_fd, "validate_cap", 246 "validate_cap_sgidnonroot"); 247 if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0) 248 err(1, "chown"); 249 if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0) 250 err(1, "chmod"); 251 } 252 253 capng_get_caps_process(); 254 255 /* Make sure that i starts out clear */ 256 capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); 257 if (capng_apply(CAPNG_SELECT_CAPS) != 0) 258 err(1, "capng_apply"); 259 260 if (uid == 0) { 261 printf("[RUN]\tRoot => ep\n"); 262 if (fork_wait()) 263 exec_validate_cap(true, true, false, false); 264 } else { 265 printf("[RUN]\tNon-root => no caps\n"); 266 if (fork_wait()) 267 exec_validate_cap(false, false, false, false); 268 } 269 270 printf("[OK]\tCheck cap_ambient manipulation rules\n"); 271 272 /* We should not be able to add ambient caps yet. */ 273 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) { 274 if (errno == EINVAL) 275 printf("[FAIL]\tPR_CAP_AMBIENT_RAISE isn't supported\n"); 276 else 277 printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n"); 278 return 1; 279 } 280 printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n"); 281 282 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW); 283 capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW); 284 capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW); 285 if (capng_apply(CAPNG_SELECT_CAPS) != 0) 286 err(1, "capng_apply"); 287 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) { 288 printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n"); 289 return 1; 290 } 291 printf("[OK]\tPR_CAP_AMBIENT_RAISE failed on non-permitted cap\n"); 292 293 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); 294 if (capng_apply(CAPNG_SELECT_CAPS) != 0) 295 err(1, "capng_apply"); 296 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) { 297 printf("[FAIL]\tPR_CAP_AMBIENT_RAISE should have succeeded\n"); 298 return 1; 299 } 300 printf("[OK]\tPR_CAP_AMBIENT_RAISE worked\n"); 301 302 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) { 303 printf("[FAIL]\tPR_CAP_AMBIENT_IS_SET is broken\n"); 304 return 1; 305 } 306 307 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0) 308 err(1, "PR_CAP_AMBIENT_CLEAR_ALL"); 309 310 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) { 311 printf("[FAIL]\tPR_CAP_AMBIENT_CLEAR_ALL didn't work\n"); 312 return 1; 313 } 314 315 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) 316 err(1, "PR_CAP_AMBIENT_RAISE"); 317 318 capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); 319 if (capng_apply(CAPNG_SELECT_CAPS) != 0) 320 err(1, "capng_apply"); 321 322 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) { 323 printf("[FAIL]\tDropping I should have dropped A\n"); 324 return 1; 325 } 326 327 printf("[OK]\tBasic manipulation appears to work\n"); 328 329 capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE); 330 if (capng_apply(CAPNG_SELECT_CAPS) != 0) 331 err(1, "capng_apply"); 332 if (uid == 0) { 333 printf("[RUN]\tRoot +i => eip\n"); 334 if (fork_wait()) 335 exec_validate_cap(true, true, true, false); 336 } else { 337 printf("[RUN]\tNon-root +i => i\n"); 338 if (fork_wait()) 339 exec_validate_cap(false, false, true, false); 340 } 341 342 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) 343 err(1, "PR_CAP_AMBIENT_RAISE"); 344 345 printf("[RUN]\tUID %d +ia => eipa\n", uid); 346 if (fork_wait()) 347 exec_validate_cap(true, true, true, true); 348 349 /* The remaining tests need real privilege */ 350 351 if (!have_outer_privilege) { 352 printf("[SKIP]\tSUID/SGID tests (needs privilege)\n"); 353 goto done; 354 } 355 356 if (uid == 0) { 357 printf("[RUN]\tRoot +ia, suidroot => eipa\n"); 358 if (fork_wait()) 359 exec_other_validate_cap("./validate_cap_suidroot", 360 true, true, true, true); 361 362 printf("[RUN]\tRoot +ia, suidnonroot => ip\n"); 363 if (fork_wait()) 364 exec_other_validate_cap("./validate_cap_suidnonroot", 365 false, true, true, false); 366 367 printf("[RUN]\tRoot +ia, sgidroot => eipa\n"); 368 if (fork_wait()) 369 exec_other_validate_cap("./validate_cap_sgidroot", 370 true, true, true, true); 371 372 if (fork_wait()) { 373 printf("[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n"); 374 if (setresgid(1, 1, 1) != 0) 375 err(1, "setresgid"); 376 exec_other_validate_cap("./validate_cap_sgidroot", 377 true, true, true, false); 378 } 379 380 printf("[RUN]\tRoot +ia, sgidnonroot => eip\n"); 381 if (fork_wait()) 382 exec_other_validate_cap("./validate_cap_sgidnonroot", 383 true, true, true, false); 384 } else { 385 printf("[RUN]\tNon-root +ia, sgidnonroot => i\n"); 386 exec_other_validate_cap("./validate_cap_sgidnonroot", 387 false, false, true, false); 388 389 if (fork_wait()) { 390 printf("[RUN]\tNon-root +ia, sgidroot => i\n"); 391 if (setresgid(1, 1, 1) != 0) 392 err(1, "setresgid"); 393 exec_other_validate_cap("./validate_cap_sgidroot", 394 false, false, true, false); 395 } 396 } 397 398 done: 399 return nerrs ? 1 : 0; 400 } 401 402 int main(int argc, char **argv) 403 { 404 char *tmp1, *tmp2, *our_path; 405 406 /* Find our path */ 407 tmp1 = strdup(argv[0]); 408 if (!tmp1) 409 err(1, "strdup"); 410 tmp2 = dirname(tmp1); 411 our_path = strdup(tmp2); 412 if (!our_path) 413 err(1, "strdup"); 414 free(tmp1); 415 416 if (fork_wait()) { 417 printf("[RUN]\t+++ Tests with uid == 0 +++\n"); 418 return do_tests(0, our_path); 419 } 420 421 if (fork_wait()) { 422 printf("[RUN]\t+++ Tests with uid != 0 +++\n"); 423 return do_tests(1, our_path); 424 } 425 426 return nerrs ? 1 : 0; 427 } 428
