linux/tools/testing/selftests/capabilities/test_execve.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0
   2#define _GNU_SOURCE
   3
   4#include <cap-ng.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
  31static int nerrs;
  32static pid_t mpid;      /*  main() pid is used to avoid duplicate test counts */
  33
  34static 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                ksft_exit_fail_msg("vsnprintf failed - %s\n", strerror(errno));
  44
  45        if (buf_len >= sizeof(buf))
  46                ksft_exit_fail_msg("vsnprintf output truncated\n");
  47
  48
  49        fd = open(filename, O_WRONLY);
  50        if (fd < 0) {
  51                if ((errno == ENOENT) && enoent_ok)
  52                        return;
  53                ksft_exit_fail_msg("open of %s failed - %s\n",
  54                                        filename, strerror(errno));
  55        }
  56        written = write(fd, buf, buf_len);
  57        if (written != buf_len) {
  58                if (written >= 0) {
  59                        ksft_exit_fail_msg("short write to %s\n", filename);
  60                } else {
  61                        ksft_exit_fail_msg("write to %s failed - %s\n",
  62                                                filename, strerror(errno));
  63                }
  64        }
  65        if (close(fd) != 0) {
  66                ksft_exit_fail_msg("close of %s failed - %s\n",
  67                                        filename, strerror(errno));
  68        }
  69}
  70
  71static void maybe_write_file(char *filename, char *fmt, ...)
  72{
  73        va_list ap;
  74
  75        va_start(ap, fmt);
  76        vmaybe_write_file(true, filename, fmt, ap);
  77        va_end(ap);
  78}
  79
  80static void write_file(char *filename, char *fmt, ...)
  81{
  82        va_list ap;
  83
  84        va_start(ap, fmt);
  85        vmaybe_write_file(false, filename, fmt, ap);
  86        va_end(ap);
  87}
  88
  89static bool create_and_enter_ns(uid_t inner_uid)
  90{
  91        uid_t outer_uid;
  92        gid_t outer_gid;
  93        int i;
  94        bool have_outer_privilege;
  95
  96        outer_uid = getuid();
  97        outer_gid = getgid();
  98
  99        /*
 100         * TODO: If we're already root, we could skip creating the userns.
 101         */
 102
 103        if (unshare(CLONE_NEWNS) == 0) {
 104                ksft_print_msg("[NOTE]\tUsing global UIDs for tests\n");
 105                if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0)
 106                        ksft_exit_fail_msg("PR_SET_KEEPCAPS - %s\n",
 107                                                strerror(errno));
 108                if (setresuid(inner_uid, inner_uid, -1) != 0)
 109                        ksft_exit_fail_msg("setresuid - %s\n", strerror(errno));
 110
 111                // Re-enable effective caps
 112                capng_get_caps_process();
 113                for (i = 0; i < CAP_LAST_CAP; i++)
 114                        if (capng_have_capability(CAPNG_PERMITTED, i))
 115                                capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, i);
 116                if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 117                        ksft_exit_fail_msg(
 118                                        "capng_apply - %s\n", strerror(errno));
 119
 120                have_outer_privilege = true;
 121        } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
 122                ksft_print_msg("[NOTE]\tUsing a user namespace for tests\n");
 123                maybe_write_file("/proc/self/setgroups", "deny");
 124                write_file("/proc/self/uid_map", "%d %d 1", inner_uid, outer_uid);
 125                write_file("/proc/self/gid_map", "0 %d 1", outer_gid);
 126
 127                have_outer_privilege = false;
 128        } else {
 129                ksft_exit_skip("must be root or be able to create a userns\n");
 130        }
 131
 132        if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0)
 133                ksft_exit_fail_msg("remount everything private - %s\n",
 134                                        strerror(errno));
 135
 136        return have_outer_privilege;
 137}
 138
 139static void chdir_to_tmpfs(void)
 140{
 141        char cwd[PATH_MAX];
 142        if (getcwd(cwd, sizeof(cwd)) != cwd)
 143                ksft_exit_fail_msg("getcwd - %s\n", strerror(errno));
 144
 145        if (mount("private_tmp", ".", "tmpfs", 0, "mode=0777") != 0)
 146                ksft_exit_fail_msg("mount private tmpfs - %s\n",
 147                                        strerror(errno));
 148
 149        if (chdir(cwd) != 0)
 150                ksft_exit_fail_msg("chdir to private tmpfs - %s\n",
 151                                        strerror(errno));
 152}
 153
 154static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
 155{
 156        int from = openat(fromfd, fromname, O_RDONLY);
 157        if (from == -1)
 158                ksft_exit_fail_msg("open copy source - %s\n", strerror(errno));
 159
 160        int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);
 161
 162        while (true) {
 163                char buf[4096];
 164                ssize_t sz = read(from, buf, sizeof(buf));
 165                if (sz == 0)
 166                        break;
 167                if (sz < 0)
 168                        ksft_exit_fail_msg("read - %s\n", strerror(errno));
 169
 170                if (write(to, buf, sz) != sz)
 171                        /* no short writes on tmpfs */
 172                        ksft_exit_fail_msg("write - %s\n", strerror(errno));
 173        }
 174
 175        close(from);
 176        close(to);
 177}
 178
 179static bool fork_wait(void)
 180{
 181        pid_t child = fork();
 182        if (child == 0) {
 183                nerrs = 0;
 184                return true;
 185        } else if (child > 0) {
 186                int status;
 187                if (waitpid(child, &status, 0) != child ||
 188                    !WIFEXITED(status)) {
 189                        ksft_print_msg("Child died\n");
 190                        nerrs++;
 191                } else if (WEXITSTATUS(status) != 0) {
 192                        ksft_print_msg("Child failed\n");
 193                        nerrs++;
 194                } else {
 195                        /* don't print this message for mpid */
 196                        if (getpid() != mpid)
 197                                ksft_test_result_pass("Passed\n");
 198                }
 199                return false;
 200        } else {
 201                ksft_exit_fail_msg("fork - %s\n", strerror(errno));
 202                return false;
 203        }
 204}
 205
 206static void exec_other_validate_cap(const char *name,
 207                                    bool eff, bool perm, bool inh, bool ambient)
 208{
 209        execl(name, name, (eff ? "1" : "0"),
 210              (perm ? "1" : "0"), (inh ? "1" : "0"), (ambient ? "1" : "0"),
 211              NULL);
 212        ksft_exit_fail_msg("execl - %s\n", strerror(errno));
 213}
 214
 215static void exec_validate_cap(bool eff, bool perm, bool inh, bool ambient)
 216{
 217        exec_other_validate_cap("./validate_cap", eff, perm, inh, ambient);
 218}
 219
 220static int do_tests(int uid, const char *our_path)
 221{
 222        bool have_outer_privilege = create_and_enter_ns(uid);
 223
 224        int ourpath_fd = open(our_path, O_RDONLY | O_DIRECTORY);
 225        if (ourpath_fd == -1)
 226                ksft_exit_fail_msg("open '%s' - %s\n",
 227                                        our_path, strerror(errno));
 228
 229        chdir_to_tmpfs();
 230
 231        copy_fromat_to(ourpath_fd, "validate_cap", "validate_cap");
 232
 233        if (have_outer_privilege) {
 234                uid_t gid = getegid();
 235
 236                copy_fromat_to(ourpath_fd, "validate_cap",
 237                               "validate_cap_suidroot");
 238                if (chown("validate_cap_suidroot", 0, -1) != 0)
 239                        ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 240                if (chmod("validate_cap_suidroot", S_ISUID | 0700) != 0)
 241                        ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 242
 243                copy_fromat_to(ourpath_fd, "validate_cap",
 244                               "validate_cap_suidnonroot");
 245                if (chown("validate_cap_suidnonroot", uid + 1, -1) != 0)
 246                        ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 247                if (chmod("validate_cap_suidnonroot", S_ISUID | 0700) != 0)
 248                        ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 249
 250                copy_fromat_to(ourpath_fd, "validate_cap",
 251                               "validate_cap_sgidroot");
 252                if (chown("validate_cap_sgidroot", -1, 0) != 0)
 253                        ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 254                if (chmod("validate_cap_sgidroot", S_ISGID | 0710) != 0)
 255                        ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 256
 257                copy_fromat_to(ourpath_fd, "validate_cap",
 258                               "validate_cap_sgidnonroot");
 259                if (chown("validate_cap_sgidnonroot", -1, gid + 1) != 0)
 260                        ksft_exit_fail_msg("chown - %s\n", strerror(errno));
 261                if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0)
 262                        ksft_exit_fail_msg("chmod - %s\n", strerror(errno));
 263        }
 264
 265        capng_get_caps_process();
 266
 267        /* Make sure that i starts out clear */
 268        capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 269        if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 270                ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 271
 272        if (uid == 0) {
 273                ksft_print_msg("[RUN]\tRoot => ep\n");
 274                if (fork_wait())
 275                        exec_validate_cap(true, true, false, false);
 276        } else {
 277                ksft_print_msg("[RUN]\tNon-root => no caps\n");
 278                if (fork_wait())
 279                        exec_validate_cap(false, false, false, false);
 280        }
 281
 282        ksft_print_msg("Check cap_ambient manipulation rules\n");
 283
 284        /* We should not be able to add ambient caps yet. */
 285        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != -1 || errno != EPERM) {
 286                if (errno == EINVAL)
 287                        ksft_test_result_fail(
 288                                "PR_CAP_AMBIENT_RAISE isn't supported\n");
 289                else
 290                        ksft_test_result_fail(
 291                                "PR_CAP_AMBIENT_RAISE should have failed eith EPERM on a non-inheritable cap\n");
 292                return 1;
 293        }
 294        ksft_test_result_pass(
 295                "PR_CAP_AMBIENT_RAISE failed on non-inheritable cap\n");
 296
 297        capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_RAW);
 298        capng_update(CAPNG_DROP, CAPNG_PERMITTED, CAP_NET_RAW);
 299        capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_NET_RAW);
 300        if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 301                ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 302        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_RAW, 0, 0, 0) != -1 || errno != EPERM) {
 303                ksft_test_result_fail(
 304                        "PR_CAP_AMBIENT_RAISE should have failed on a non-permitted cap\n");
 305                return 1;
 306        }
 307        ksft_test_result_pass(
 308                "PR_CAP_AMBIENT_RAISE failed on non-permitted cap\n");
 309
 310        capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 311        if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 312                ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 313        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
 314                ksft_test_result_fail(
 315                        "PR_CAP_AMBIENT_RAISE should have succeeded\n");
 316                return 1;
 317        }
 318        ksft_test_result_pass("PR_CAP_AMBIENT_RAISE worked\n");
 319
 320        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 1) {
 321                ksft_test_result_fail("PR_CAP_AMBIENT_IS_SET is broken\n");
 322                return 1;
 323        }
 324
 325        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0, 0) != 0)
 326                ksft_exit_fail_msg("PR_CAP_AMBIENT_CLEAR_ALL - %s\n",
 327                                        strerror(errno));
 328
 329        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
 330                ksft_test_result_fail(
 331                        "PR_CAP_AMBIENT_CLEAR_ALL didn't work\n");
 332                return 1;
 333        }
 334
 335        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
 336                ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
 337                                        strerror(errno));
 338
 339        capng_update(CAPNG_DROP, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 340        if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 341                ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 342
 343        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0) {
 344                ksft_test_result_fail("Dropping I should have dropped A\n");
 345                return 1;
 346        }
 347
 348        ksft_test_result_pass("Basic manipulation appears to work\n");
 349
 350        capng_update(CAPNG_ADD, CAPNG_INHERITABLE, CAP_NET_BIND_SERVICE);
 351        if (capng_apply(CAPNG_SELECT_CAPS) != 0)
 352                ksft_exit_fail_msg("capng_apply - %s\n", strerror(errno));
 353        if (uid == 0) {
 354                ksft_print_msg("[RUN]\tRoot +i => eip\n");
 355                if (fork_wait())
 356                        exec_validate_cap(true, true, true, false);
 357        } else {
 358                ksft_print_msg("[RUN]\tNon-root +i => i\n");
 359                if (fork_wait())
 360                        exec_validate_cap(false, false, true, false);
 361        }
 362
 363        if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, CAP_NET_BIND_SERVICE, 0, 0, 0) != 0)
 364                ksft_exit_fail_msg("PR_CAP_AMBIENT_RAISE - %s\n",
 365                                        strerror(errno));
 366
 367        ksft_print_msg("[RUN]\tUID %d +ia => eipa\n", uid);
 368        if (fork_wait())
 369                exec_validate_cap(true, true, true, true);
 370
 371        /* The remaining tests need real privilege */
 372
 373        if (!have_outer_privilege) {
 374                ksft_test_result_skip("SUID/SGID tests (needs privilege)\n");
 375                goto done;
 376        }
 377
 378        if (uid == 0) {
 379                ksft_print_msg("[RUN]\tRoot +ia, suidroot => eipa\n");
 380                if (fork_wait())
 381                        exec_other_validate_cap("./validate_cap_suidroot",
 382                                                true, true, true, true);
 383
 384                ksft_print_msg("[RUN]\tRoot +ia, suidnonroot => ip\n");
 385                if (fork_wait())
 386                        exec_other_validate_cap("./validate_cap_suidnonroot",
 387                                                false, true, true, false);
 388
 389                ksft_print_msg("[RUN]\tRoot +ia, sgidroot => eipa\n");
 390                if (fork_wait())
 391                        exec_other_validate_cap("./validate_cap_sgidroot",
 392                                                true, true, true, true);
 393
 394                if (fork_wait()) {
 395                        ksft_print_msg(
 396                                "[RUN]\tRoot, gid != 0, +ia, sgidroot => eip\n");
 397                        if (setresgid(1, 1, 1) != 0)
 398                                ksft_exit_fail_msg("setresgid - %s\n",
 399                                                        strerror(errno));
 400                        exec_other_validate_cap("./validate_cap_sgidroot",
 401                                                true, true, true, false);
 402                }
 403
 404                ksft_print_msg("[RUN]\tRoot +ia, sgidnonroot => eip\n");
 405                if (fork_wait())
 406                        exec_other_validate_cap("./validate_cap_sgidnonroot",
 407                                                true, true, true, false);
 408        } else {
 409                ksft_print_msg("[RUN]\tNon-root +ia, sgidnonroot => i\n");
 410                if (fork_wait())
 411                        exec_other_validate_cap("./validate_cap_sgidnonroot",
 412                                        false, false, true, false);
 413
 414                if (fork_wait()) {
 415                        ksft_print_msg("[RUN]\tNon-root +ia, sgidroot => i\n");
 416                        if (setresgid(1, 1, 1) != 0)
 417                                ksft_exit_fail_msg("setresgid - %s\n",
 418                                                        strerror(errno));
 419                        exec_other_validate_cap("./validate_cap_sgidroot",
 420                                                false, false, true, false);
 421                }
 422        }
 423
 424done:
 425        ksft_print_cnts();
 426        return nerrs ? 1 : 0;
 427}
 428
 429int main(int argc, char **argv)
 430{
 431        char *tmp1, *tmp2, *our_path;
 432
 433        /* Find our path */
 434        tmp1 = strdup(argv[0]);
 435        if (!tmp1)
 436                ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
 437        tmp2 = dirname(tmp1);
 438        our_path = strdup(tmp2);
 439        if (!our_path)
 440                ksft_exit_fail_msg("strdup - %s\n", strerror(errno));
 441        free(tmp1);
 442
 443        mpid = getpid();
 444
 445        if (fork_wait()) {
 446                ksft_print_header();
 447                ksft_set_plan(12);
 448                ksft_print_msg("[RUN]\t+++ Tests with uid == 0 +++\n");
 449                return do_tests(0, our_path);
 450        }
 451
 452        ksft_print_msg("==================================================\n");
 453
 454        if (fork_wait()) {
 455                ksft_print_header();
 456                ksft_set_plan(9);
 457                ksft_print_msg("[RUN]\t+++ Tests with uid != 0 +++\n");
 458                return do_tests(1, our_path);
 459        }
 460
 461        return nerrs ? 1 : 0;
 462}
 463