tools/testing/selftests/capabilities/test_execve.c

   1 #define _GNU_SOURCE
   2
   3 #include <cap-ng.h>
   4 #include <linux/capability.h>
   5 #include <stdbool.h>
   6 #include <string.h>
   7 #include <stdio.h>
   8 #include <fcntl.h>
   9 #include <errno.h>
  10 #include <stdarg.h>
  11 #include <sched.h>
  12 #include <sys/mount.h>
  13 #include <limits.h>
  14 #include <libgen.h>
  15 #include <malloc.h>
  16 #include <sys/wait.h>
  17 #include <sys/prctl.h>
  18 #include <sys/stat.h>
  19
  20 #include "../kselftest.h"
  21
  22 #ifndef PR_CAP_AMBIENT
  23 #define PR_CAP_AMBIENT                  47
  24 # define PR_CAP_AMBIENT_IS_SET          1
  25 # define PR_CAP_AMBIENT_RAISE           2
  26 # define PR_CAP_AMBIENT_LOWER           3
  27 # define PR_CAP_AMBIENT_CLEAR_ALL       4
  28 #endif
  29
  30 static int nerrs;
  31 static pid_t mpid;      /*  main() pid is used to avoid duplicate test counts */
  32
  33 static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap)
  34 {
  35         char buf[4096];
  36         int fd;
  37         ssize_t written;
  38         int buf_len;
  39
  40         buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);
  41         if (buf_len < 0)
  42                 ksft_exit_fail_msg("vsnprintf failed - %s\n", strerror(errno));
  43
  44         if (buf_len >= sizeof(buf))
  45                 ksft_exit_fail_msg("vsnprintf output truncated\n");
  46
  47
  48         fd = open(filename, O_WRONLY);
  49         if (fd < 0) {
  50                 if ((errno == ENOENT) && enoent_ok)
  51                         return;
  52                 ksft_exit_fail_msg("open of %s failed - %s\n",
  53                                         filename, strerror(errno));
  54         }
  55         written = write(fd, buf, buf_len);
  56         if (written != buf_len) {
  57                 if (written >= 0) {
  58                         ksft_exit_fail_msg("short write to %s\n", filename);
  59                 } else {
  60                         ksft_exit_fail_msg("write to %s failed - %s\n",
  61                                                 filename, strerror(errno));
  62                 }
  63         }
  64         if (close(fd) != 0) {
  65                 ksft_exit_fail_msg("close of %s failed - %s\n",
  66                                         filename, strerror(errno));
  67         }
  68 }
  69
  70 static void maybe_write_file(char *filename, char *fmt, ...)
  71 {
  72         va_list ap;
  73
  74         va_start(ap, fmt);
  75         vmaybe_write_file(true, filename, fmt, ap);
  76         va_end(ap);
  77 }
  78
  79 static void write_file(char *filename, char *fmt, ...)
  80 {
  81         va_list ap;
  82
  83         va_start(ap, fmt);
  84         vmaybe_write_file(false, filename, fmt, ap);
  85         va_end(ap);
  86 }
  87
  88 static bool create_and_enter_ns(uid_t inner_uid)
  89 {
  90         uid_t outer_uid;
  91         gid_t outer_gid;
  92         int i;
  93         bool have_outer_privilege;
  94
  95         outer_uid = getuid();
  96         outer_gid = getgid();
  97
  98         /*
  99          * TODO: If we're already root, we could skip creating the userns.
 100          */
 101
 102         if (unshare(CLONE_NEWNS) == 0) {
 103                 ksft_print_msg("[NOTE]\tUsing global UIDs for tests\n");
 104                 if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0)
 105                         ksft_exit_fail_msg("PR_SET_KEEPCAPS - %s\n",
 106                                                 strerror(errno));
 107                 if (setresuid(inner_uid, inner_uid, -1) != 0)
 108                         ksft_exit_fail_msg("setresuid - %s\n", strerror(errno));
 109
 110                 // Re-enable effective caps
 111                 capng_get_caps_process();
 112                 for (i = 0; i < CAP_LAST_CAP; i++)
 113                         if (capng_have_capability(CAPNG_PERMITTED, i))
 114                                 capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, i);
 115                 if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 116                         ksft_exit_fail_msg(
 117                                         "capng_apply - %s\n", strerror(errno));
 118
 119                 have_outer_privilege = true;
 120         } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
 121                 ksft_print_msg("[NOTE]\tUsing a user namespace for tests\n");
 122                 maybe_write_file("/proc/self/setgroups", "deny");
 123                 write_file("/proc/self/uid_map", "%d %d 1", inner_uid, outer_uid);
 124                 write_file("/proc/self/gid_map", "0 %d 1", outer_gid);
 125
 126                 have_outer_privilege = false;
 127         } else {
 128                 ksft_exit_skip("must be root or be able to create a userns\n");
 129         }
 130
 131         if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0)
 132                 ksft_exit_fail_msg("remount everything private - %s\n",
 133                                         strerror(errno));
 134
 135         return have_outer_privilege;
 136 }
 137
 138 static void chdir_to_tmpfs(void)
 139 {
 140         char cwd[PATH_MAX];
 141         if (getcwd(cwd, sizeof(cwd)) != cwd)
 142                 ksft_exit_fail_msg("getcwd - %s\n", strerror(errno));
 143
 144         if (mount("private_tmp", ".", "tmpfs", 0, "mode=0777") != 0)
 145                 ksft_exit_fail_msg("mount private tmpfs - %s\n",
 146                                         strerror(errno));
 147
 148         if (chdir(cwd) != 0)
 149                 ksft_exit_fail_msg("chdir to private tmpfs - %s\n",
 150                                         strerror(errno));
 151 }
 152
 153 static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
 154 {
 155         int from = openat(fromfd, fromname, O_RDONLY);
 156         if (from == -1)
 157                 ksft_exit_fail_msg("open copy source - %s\n", strerror(errno));
 158
 159         int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);
 160
 161         while (true) {
 162                 char buf[4096];
 163                 ssize_t sz = read(from, buf, sizeof(buf));
 164                 if (sz == 0)
 165                         break;
 166                 if (sz < 0)
 167                         ksft_exit_fail_msg("read - %s\n", strerror(errno));
 168
 169                 if (write(to, buf, sz) != sz)
 170                         /* no short writes on tmpfs */
 171                         ksft_exit_fail_msg("write - %s\n", strerror(errno));
 172         }
 173
 174         close(from);
 175         close(to);
 176 }
 177
 178 static bool fork_wait(void)
 179 {
 180         pid_t child = fork();
 181         if (child == 0) {
 182                 nerrs = 0;
 183                 return true;
 184         } else if (child > 0) {
 185                 int status;
 186                 if (waitpid(child, &status, 0) != child ||
 187                     !WIFEXITED(status)) {
 188                         ksft_print_msg("Child died\n");
 189                         nerrs++;
 190                 } else if (WEXITSTATUS(status) != 0) {
 191                         ksft_print_msg("Child failed\n");
 192                         nerrs++;
 193                 } else {
 194                         /* don't print this message for mpid */
 195                         if (getpid() != mpid)
 196                                 ksft_test_result_pass("Passed\n");
 197                 }
 198                 return false;
 199         } else {
 200                 ksft_exit_fail_msg("fork - %s\n", strerror(errno));
 201                 return false;
 202         }
 203 }
 204
 205 static void exec_other_validate_cap(const char *name,
 206                                     bool eff, bool perm, bool inh, bool ambient)
 207 {
 208         execl(name, name, (eff ? "1" : "0"),
 209               (perm ? "1" : "0"), (inh ? "1" : "0"), (ambient ? "1" : "0"),
 210               NULL);
 211         ksft_exit_fail_msg("execl - %s\n", strerror(errno));
 212 }
 213
 214 static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient)
 215 {
 216         exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient);
 217 }
 218
 219 static int do_tests(int uid, const char *our_path)
 220 {
 221         bool have_outer_privilege = create_and_enter_ns(uid);
 222
 223         int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY);
 224         if (ourpath_fd == -1)
 225                 ksft_exit_fail_msg("open '%s' - %s\n",
 226                                         our_path, strerror(errno));
 227
 228         chdir_to_tmpfs();
 229
 230         copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap");
 231
 232         if (have_outer_privilege) {
 233                 uid_t gid = getegid();
 234
 235                 copy_fromat_to(ourpath_fd, "validate_cap",
 236                                "validate_cap_suidroot");
 237                 if (chown("validate_cap_suidroot", 0, -1) != 0)
 238                         ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 239                 if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0)
 240                         ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 241
 242                 copy_fromat_to(ourpath_fd, "validate_cap",
 243                                "validate_cap_suidnonroot");
 244                 if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0)
 245                         ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 246                 if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0)
 247                         ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 248
 249                 copy_fromat_to(ourpath_fd, "validate_cap",
 250                                "validate_cap_sgidroot");
 251                 if (chown("validate_cap_sgidroot", -1, 0) != 0)
 252                         ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 253                 if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0)
 254                         ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 255
 256                 copy_fromat_to(ourpath_fd, "validate_cap",
 257                                "validate_cap_sgidnonroot");
 258                 if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0)
 259                         ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 260                 if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0)
 261                         ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 262         }
 263
 264         capng_get_caps_process();
 265
 266         /* Make sure that i starts out clear */
 267         capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 268         if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 269                 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 270
 271         if (uid == 0) {
 272                 ksft_print_msg("[RUN]\tRoot => ep\n");
 273                 if (fork_wait())
 274                         exec_validate_cap(true, true, false, false);
 275         } else {
 276                 ksft_print_msg("[RUN]\tNon-root => no caps\n");
 277                 if (fork_wait())
 278                         exec_validate_cap(false, false, false, false);
 279         }
 280
 281         ksft_print_msg("Check cap_ambient manipulation rules\n");
 282
 283         /* We should not be able to add ambient caps yet. */
 284         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) {
 285                 if (errno == EINVAL)
 286                         ksft_test_result_fail(
 287                                 "PR_CAP_AMBIENT_RAISE isn't supported\n");
 288                 else
 289                         ksft_test_result_fail(
 290                                 "PR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n");
 291                 return 1;
 292         }
 293         ksft_test_result_pass(
 294                 "PR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n");
 295
 296         capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW);
 297         capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW);
 298         capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW);
 299         if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 300                 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 301         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) {
 302                 ksft_test_result_fail(
 303                         "PR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n");
 304                 return 1;
 305         }
 306         ksft_test_result_pass(
 307                 "PR_CAP_AMBIENT_RAISE failed on non-permitted cap\n");
 308
 309         capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 310         if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 311                 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 312         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
 313                 ksft_test_result_fail(
 314                         "PR_CAP_AMBIENT_RAISE should have succeeded\n");
 315                 return 1;
 316         }
 317         ksft_test_result_pass("PR_CAP_AMBIENT_RAISE worked\n");
 318
 319         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) {
 320                 ksft_test_result_fail("PR_CAP_AMBIENT_IS_SET is broken\n");
 321                 return 1;
 322         }
 323
 324         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0)
 325                 ksft_exit_fail_msg("PR_CAP_AMBIENT_CLEAR_ALL - %s\n",
 326                                         strerror(errno));
 327
 328         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
 329                 ksft_test_result_fail(
 330                         "PR_CAP_AMBIENT_CLEAR_ALL didn't work\n");
 331                 return 1;
 332         }
 333
 334         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
 335                 ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
 336                                         strerror(errno));
 337
 338         capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 339         if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 340                 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 341
 342         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
 343                 ksft_test_result_fail("Dropping I should have dropped A\n");
 344                 return 1;
 345         }
 346
 347         ksft_test_result_pass("Basic manipulation appears to work\n");
 348
 349         capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 350         if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 351                 ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 352         if (uid == 0) {
 353                 ksft_print_msg("[RUN]\tRoot +i => eip\n");
 354                 if (fork_wait())
 355                         exec_validate_cap(true, true, true, false);
 356         } else {
 357                 ksft_print_msg("[RUN]\tNon-root +i => i\n");
 358                 if (fork_wait())
 359                         exec_validate_cap(false, false, true, false);
 360         }
 361
 362         if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
 363                 ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
 364                                         strerror(errno));
 365
 366         ksft_print_msg("[RUN]\tUID %d +ia => eipa\n", uid);
 367         if (fork_wait())
 368                 exec_validate_cap(true, true, true, true);
 369
 370         /* The remaining tests need real privilege */
 371
 372         if (!have_outer_privilege) {
 373                 ksft_test_result_skip("SUID/SGID tests (needs privilege)\n");
 374                 goto done;
 375         }
 376
 377         if (uid == 0) {
 378                 ksft_print_msg("[RUN]\tRoot +ia, suidroot => eipa\n");
 379                 if (fork_wait())
 380                         exec_other_validate_cap("./validate_cap_suidroot",
 381                                                 true, true, true, true);
 382
 383                 ksft_print_msg("[RUN]\tRoot +ia, suidnonroot => ip\n");
 384                 if (fork_wait())
 385                         exec_other_validate_cap("./validate_cap_suidnonroot",
 386                                                 false, true, true, false);
 387
 388                 ksft_print_msg("[RUN]\tRoot +ia, sgidroot => eipa\n");
 389                 if (fork_wait())
 390                         exec_other_validate_cap("./validate_cap_sgidroot",
 391                                                 true, true, true, true);
 392
 393                 if (fork_wait()) {
 394                         ksft_print_msg(
 395                                 "[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n");
 396                         if (setresgid(1, 1, 1) != 0)
 397                                 ksft_exit_fail_msg("setresgid - %s\n",
 398                                                         strerror(errno));
 399                         exec_other_validate_cap("./validate_cap_sgidroot",
 400                                                 true, true, true, false);
 401                 }
 402
 403                 ksft_print_msg("[RUN]\tRoot +ia, sgidnonroot => eip\n");
 404                 if (fork_wait())
 405                         exec_other_validate_cap("./validate_cap_sgidnonroot",
 406                                                 true, true, true, false);
 407         } else {
 408                 ksft_print_msg("[RUN]\tNon-root +ia, sgidnonroot => i\n");
 409                 if (fork_wait())
 410                         exec_other_validate_cap("./validate_cap_sgidnonroot",
 411                                         false, false, true, false);
 412
 413                 if (fork_wait()) {
 414                         ksft_print_msg("[RUN]\tNon-root +ia, sgidroot => i\n");
 415                         if (setresgid(1, 1, 1) != 0)
 416                                 ksft_exit_fail_msg("setresgid - %s\n",
 417                                                         strerror(errno));
 418                         exec_other_validate_cap("./validate_cap_sgidroot",
 419                                                 false, false, true, false);
 420                 }
 421         }
 422
 423 done:
 424         ksft_print_cnts();
 425         return nerrs ? 1 : 0;
 426 }
 427
 428 int main(int argc, char **argv)
 429 {
 430         char *tmp1, *tmp2, *our_path;
 431
 432         ksft_print_header();
 433
 434         /* Find our path */
 435         tmp1 = strdup(argv[0]);
 436         if (!tmp1)
 437                 ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
 438         tmp2 = dirname(tmp1);
 439         our_path = strdup(tmp2);
 440         if (!our_path)
 441                 ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
 442         free(tmp1);
 443
 444         mpid = getpid();
 445
 446         if (fork_wait()) {
 447                 ksft_print_msg("[RUN]\t+++ Tests with uid == 0 +++\n");
 448                 return do_tests(0, our_path);
 449         }
 450
 451         ksft_print_msg("==================================================\n");
 452
 453         if (fork_wait()) {
 454                 ksft_print_msg("[RUN]\t+++ Tests with uid != 0 +++\n");
 455                 return do_tests(1, our_path);
 456         }
 457
 458         return nerrs ? 1 : 0;
 459 }