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