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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (c) 2014 Google, Inc.4 *5 * Selftests for execveat(2).6 */7 8#ifndef _GNU_SOURCE9#define _GNU_SOURCE /* to get O_PATH, AT_EMPTY_PATH */10#endif11#include <sys/sendfile.h>12#include <sys/stat.h>13#include <sys/syscall.h>14#include <sys/types.h>15#include <sys/wait.h>16#include <errno.h>17#include <fcntl.h>18#include <limits.h>19#include <stdio.h>20#include <stdlib.h>21#include <string.h>22#include <unistd.h>23 24#include "../kselftest.h"25 26#define TESTS_EXPECTED 5127#define TEST_NAME_LEN (PATH_MAX * 4)28 29static char longpath[2 * PATH_MAX] = "";30static char *envp[] = { "IN_TEST=yes", NULL, NULL };31static char *argv[] = { "execveat", "99", NULL };32 33static int execveat_(int fd, const char *path, char **argv, char **envp,34 int flags)35{36#ifdef __NR_execveat37 return syscall(__NR_execveat, fd, path, argv, envp, flags);38#else39 errno = ENOSYS;40 return -1;41#endif42}43 44#define check_execveat_fail(fd, path, flags, errno) \45 _check_execveat_fail(fd, path, flags, errno, #errno)46static int _check_execveat_fail(int fd, const char *path, int flags,47 int expected_errno, const char *errno_str)48{49 char test_name[TEST_NAME_LEN];50 int rc;51 52 errno = 0;53 snprintf(test_name, sizeof(test_name),54 "Check failure of execveat(%d, '%s', %d) with %s",55 fd, path?:"(null)", flags, errno_str);56 rc = execveat_(fd, path, argv, envp, flags);57 58 if (rc > 0) {59 ksft_print_msg("unexpected success from execveat(2)\n");60 ksft_test_result_fail("%s\n", test_name);61 return 1;62 }63 if (errno != expected_errno) {64 ksft_print_msg("expected errno %d (%s) not %d (%s)\n",65 expected_errno, strerror(expected_errno),66 errno, strerror(errno));67 ksft_test_result_fail("%s\n", test_name);68 return 1;69 }70 ksft_test_result_pass("%s\n", test_name);71 return 0;72}73 74static int check_execveat_invoked_rc(int fd, const char *path, int flags,75 int expected_rc, int expected_rc2)76{77 char test_name[TEST_NAME_LEN];78 int status;79 int rc;80 pid_t child;81 int pathlen = path ? strlen(path) : 0;82 83 if (pathlen > 40)84 snprintf(test_name, sizeof(test_name),85 "Check success of execveat(%d, '%.20s...%s', %d)... ",86 fd, path, (path + pathlen - 20), flags);87 else88 snprintf(test_name, sizeof(test_name),89 "Check success of execveat(%d, '%s', %d)... ",90 fd, path?:"(null)", flags);91 92 child = fork();93 if (child < 0) {94 ksft_perror("fork() failed");95 ksft_test_result_fail("%s\n", test_name);96 return 1;97 }98 if (child == 0) {99 /* Child: do execveat(). */100 rc = execveat_(fd, path, argv, envp, flags);101 ksft_print_msg("child execveat() failed, rc=%d errno=%d (%s)\n",102 rc, errno, strerror(errno));103 exit(errno);104 }105 /* Parent: wait for & check child's exit status. */106 rc = waitpid(child, &status, 0);107 if (rc != child) {108 ksft_print_msg("waitpid(%d,...) returned %d\n", child, rc);109 ksft_test_result_fail("%s\n", test_name);110 return 1;111 }112 if (!WIFEXITED(status)) {113 ksft_print_msg("child %d did not exit cleanly, status=%08x\n",114 child, status);115 ksft_test_result_fail("%s\n", test_name);116 return 1;117 }118 if ((WEXITSTATUS(status) != expected_rc) &&119 (WEXITSTATUS(status) != expected_rc2)) {120 ksft_print_msg("child %d exited with %d neither %d nor %d\n",121 child, WEXITSTATUS(status), expected_rc,122 expected_rc2);123 ksft_test_result_fail("%s\n", test_name);124 return 1;125 }126 ksft_test_result_pass("%s\n", test_name);127 return 0;128}129 130static int check_execveat(int fd, const char *path, int flags)131{132 return check_execveat_invoked_rc(fd, path, flags, 99, 99);133}134 135static char *concat(const char *left, const char *right)136{137 char *result = malloc(strlen(left) + strlen(right) + 1);138 139 strcpy(result, left);140 strcat(result, right);141 return result;142}143 144static int open_or_die(const char *filename, int flags)145{146 int fd = open(filename, flags);147 148 if (fd < 0)149 ksft_exit_fail_msg("Failed to open '%s'; "150 "check prerequisites are available\n", filename);151 return fd;152}153 154static void exe_cp(const char *src, const char *dest)155{156 int in_fd = open_or_die(src, O_RDONLY);157 int out_fd = open(dest, O_RDWR|O_CREAT|O_TRUNC, 0755);158 struct stat info;159 160 fstat(in_fd, &info);161 sendfile(out_fd, in_fd, NULL, info.st_size);162 close(in_fd);163 close(out_fd);164}165 166#define XX_DIR_LEN 200167static int check_execveat_pathmax(int root_dfd, const char *src, int is_script)168{169 int fail = 0;170 int ii, count, len;171 char longname[XX_DIR_LEN + 1];172 int fd;173 174 if (*longpath == '\0') {175 /* Create a filename close to PATH_MAX in length */176 char *cwd = getcwd(NULL, 0);177 178 if (!cwd) {179 ksft_perror("Failed to getcwd()");180 return 2;181 }182 strcpy(longpath, cwd);183 strcat(longpath, "/");184 memset(longname, 'x', XX_DIR_LEN - 1);185 longname[XX_DIR_LEN - 1] = '/';186 longname[XX_DIR_LEN] = '\0';187 count = (PATH_MAX - 3 - strlen(cwd)) / XX_DIR_LEN;188 for (ii = 0; ii < count; ii++) {189 strcat(longpath, longname);190 mkdir(longpath, 0755);191 }192 len = (PATH_MAX - 3 - strlen(cwd)) - (count * XX_DIR_LEN);193 if (len <= 0)194 len = 1;195 memset(longname, 'y', len);196 longname[len] = '\0';197 strcat(longpath, longname);198 free(cwd);199 }200 exe_cp(src, longpath);201 202 /*203 * Execute as a pre-opened file descriptor, which works whether this is204 * a script or not (because the interpreter sees a filename like205 * "/dev/fd/20").206 */207 fd = open(longpath, O_RDONLY);208 if (fd > 0) {209 ksft_print_msg("Invoke copy of '%s' via filename of length %zu:\n",210 src, strlen(longpath));211 fail += check_execveat(fd, "", AT_EMPTY_PATH);212 } else {213 ksft_print_msg("Failed to open length %zu filename, errno=%d (%s)\n",214 strlen(longpath), errno, strerror(errno));215 fail++;216 }217 218 /*219 * Execute as a long pathname relative to "/". If this is a script,220 * the interpreter will launch but fail to open the script because its221 * name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.222 *223 * The failure code is usually 127 (POSIX: "If a command is not found,224 * the exit status shall be 127."), but some systems give 126 (POSIX:225 * "If the command name is found, but it is not an executable utility,226 * the exit status shall be 126."), so allow either.227 */228 if (is_script) {229 ksft_print_msg("Invoke script via root_dfd and relative filename\n");230 fail += check_execveat_invoked_rc(root_dfd, longpath + 1, 0,231 127, 126);232 } else {233 ksft_print_msg("Invoke exec via root_dfd and relative filename\n");234 fail += check_execveat(root_dfd, longpath + 1, 0);235 }236 237 return fail;238}239 240static int run_tests(void)241{242 int fail = 0;243 char *fullname = realpath("execveat", NULL);244 char *fullname_script = realpath("script", NULL);245 char *fullname_symlink = concat(fullname, ".symlink");246 int subdir_dfd = open_or_die("subdir", O_DIRECTORY|O_RDONLY);247 int subdir_dfd_ephemeral = open_or_die("subdir.ephemeral",248 O_DIRECTORY|O_RDONLY);249 int dot_dfd = open_or_die(".", O_DIRECTORY|O_RDONLY);250 int root_dfd = open_or_die("/", O_DIRECTORY|O_RDONLY);251 int dot_dfd_path = open_or_die(".", O_DIRECTORY|O_RDONLY|O_PATH);252 int dot_dfd_cloexec = open_or_die(".", O_DIRECTORY|O_RDONLY|O_CLOEXEC);253 int fd = open_or_die("execveat", O_RDONLY);254 int fd_path = open_or_die("execveat", O_RDONLY|O_PATH);255 int fd_symlink = open_or_die("execveat.symlink", O_RDONLY);256 int fd_denatured = open_or_die("execveat.denatured", O_RDONLY);257 int fd_denatured_path = open_or_die("execveat.denatured",258 O_RDONLY|O_PATH);259 int fd_script = open_or_die("script", O_RDONLY);260 int fd_ephemeral = open_or_die("execveat.ephemeral", O_RDONLY);261 int fd_ephemeral_path = open_or_die("execveat.path.ephemeral",262 O_RDONLY|O_PATH);263 int fd_script_ephemeral = open_or_die("script.ephemeral", O_RDONLY);264 int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);265 int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);266 267 /* Check if we have execveat at all, and bail early if not */268 errno = 0;269 execveat_(-1, NULL, NULL, NULL, 0);270 if (errno == ENOSYS) {271 ksft_exit_skip(272 "ENOSYS calling execveat - no kernel support?\n");273 }274 275 /* Change file position to confirm it doesn't affect anything */276 lseek(fd, 10, SEEK_SET);277 278 /* Normal executable file: */279 /* dfd + path */280 fail += check_execveat(subdir_dfd, "../execveat", 0);281 fail += check_execveat(dot_dfd, "execveat", 0);282 fail += check_execveat(dot_dfd_path, "execveat", 0);283 /* absolute path */284 fail += check_execveat(AT_FDCWD, fullname, 0);285 /* absolute path with nonsense dfd */286 fail += check_execveat(99, fullname, 0);287 /* fd + no path */288 fail += check_execveat(fd, "", AT_EMPTY_PATH);289 /* O_CLOEXEC fd + no path */290 fail += check_execveat(fd_cloexec, "", AT_EMPTY_PATH);291 /* O_PATH fd */292 fail += check_execveat(fd_path, "", AT_EMPTY_PATH);293 294 /* Mess with executable file that's already open: */295 /* fd + no path to a file that's been renamed */296 rename("execveat.ephemeral", "execveat.moved");297 fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);298 /* fd + no path to a file that's been deleted */299 unlink("execveat.moved"); /* remove the file now fd open */300 fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);301 302 /* Mess with executable file that's already open with O_PATH */303 /* fd + no path to a file that's been deleted */304 unlink("execveat.path.ephemeral");305 fail += check_execveat(fd_ephemeral_path, "", AT_EMPTY_PATH);306 307 /* Invalid argument failures */308 fail += check_execveat_fail(fd, "", 0, ENOENT);309 fail += check_execveat_fail(fd, NULL, AT_EMPTY_PATH, EFAULT);310 311 /* Symlink to executable file: */312 /* dfd + path */313 fail += check_execveat(dot_dfd, "execveat.symlink", 0);314 fail += check_execveat(dot_dfd_path, "execveat.symlink", 0);315 /* absolute path */316 fail += check_execveat(AT_FDCWD, fullname_symlink, 0);317 /* fd + no path, even with AT_SYMLINK_NOFOLLOW (already followed) */318 fail += check_execveat(fd_symlink, "", AT_EMPTY_PATH);319 fail += check_execveat(fd_symlink, "",320 AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);321 322 /* Symlink fails when AT_SYMLINK_NOFOLLOW set: */323 /* dfd + path */324 fail += check_execveat_fail(dot_dfd, "execveat.symlink",325 AT_SYMLINK_NOFOLLOW, ELOOP);326 fail += check_execveat_fail(dot_dfd_path, "execveat.symlink",327 AT_SYMLINK_NOFOLLOW, ELOOP);328 /* absolute path */329 fail += check_execveat_fail(AT_FDCWD, fullname_symlink,330 AT_SYMLINK_NOFOLLOW, ELOOP);331 332 /* Non-regular file failure */333 fail += check_execveat_fail(dot_dfd, "pipe", 0, EACCES);334 unlink("pipe");335 336 /* Shell script wrapping executable file: */337 /* dfd + path */338 fail += check_execveat(subdir_dfd, "../script", 0);339 fail += check_execveat(dot_dfd, "script", 0);340 fail += check_execveat(dot_dfd_path, "script", 0);341 /* absolute path */342 fail += check_execveat(AT_FDCWD, fullname_script, 0);343 /* fd + no path */344 fail += check_execveat(fd_script, "", AT_EMPTY_PATH);345 fail += check_execveat(fd_script, "",346 AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);347 /* O_CLOEXEC fd fails for a script (as script file inaccessible) */348 fail += check_execveat_fail(fd_script_cloexec, "", AT_EMPTY_PATH,349 ENOENT);350 fail += check_execveat_fail(dot_dfd_cloexec, "script", 0, ENOENT);351 352 /* Mess with script file that's already open: */353 /* fd + no path to a file that's been renamed */354 rename("script.ephemeral", "script.moved");355 fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);356 /* fd + no path to a file that's been deleted */357 unlink("script.moved"); /* remove the file while fd open */358 fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);359 360 /* Rename a subdirectory in the path: */361 rename("subdir.ephemeral", "subdir.moved");362 fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);363 fail += check_execveat(subdir_dfd_ephemeral, "script", 0);364 /* Remove the subdir and its contents */365 unlink("subdir.moved/script");366 unlink("subdir.moved");367 /* Shell loads via deleted subdir OK because name starts with .. */368 fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);369 fail += check_execveat_fail(subdir_dfd_ephemeral, "script", 0, ENOENT);370 371 /* Flag values other than AT_SYMLINK_NOFOLLOW => EINVAL */372 fail += check_execveat_fail(dot_dfd, "execveat", 0xFFFF, EINVAL);373 /* Invalid path => ENOENT */374 fail += check_execveat_fail(dot_dfd, "no-such-file", 0, ENOENT);375 fail += check_execveat_fail(dot_dfd_path, "no-such-file", 0, ENOENT);376 fail += check_execveat_fail(AT_FDCWD, "no-such-file", 0, ENOENT);377 /* Attempt to execute directory => EACCES */378 fail += check_execveat_fail(dot_dfd, "", AT_EMPTY_PATH, EACCES);379 /* Attempt to execute non-executable => EACCES */380 fail += check_execveat_fail(dot_dfd, "Makefile", 0, EACCES);381 fail += check_execveat_fail(fd_denatured, "", AT_EMPTY_PATH, EACCES);382 fail += check_execveat_fail(fd_denatured_path, "", AT_EMPTY_PATH,383 EACCES);384 /* Attempt to execute nonsense FD => EBADF */385 fail += check_execveat_fail(99, "", AT_EMPTY_PATH, EBADF);386 fail += check_execveat_fail(99, "execveat", 0, EBADF);387 /* Attempt to execute relative to non-directory => ENOTDIR */388 fail += check_execveat_fail(fd, "execveat", 0, ENOTDIR);389 390 fail += check_execveat_pathmax(root_dfd, "execveat", 0);391 fail += check_execveat_pathmax(root_dfd, "script", 1);392 return fail;393}394 395static void prerequisites(void)396{397 int fd;398 const char *script = "#!/bin/bash\nexit $*\n";399 400 /* Create ephemeral copies of files */401 exe_cp("execveat", "execveat.ephemeral");402 exe_cp("execveat", "execveat.path.ephemeral");403 exe_cp("script", "script.ephemeral");404 mkdir("subdir.ephemeral", 0755);405 406 fd = open("subdir.ephemeral/script", O_RDWR|O_CREAT|O_TRUNC, 0755);407 write(fd, script, strlen(script));408 close(fd);409 410 mkfifo("pipe", 0755);411}412 413int main(int argc, char **argv)414{415 int ii;416 int rc;417 const char *verbose = getenv("VERBOSE");418 419 if (argc >= 2) {420 /* If we are invoked with an argument, don't run tests. */421 const char *in_test = getenv("IN_TEST");422 423 if (verbose) {424 ksft_print_msg("invoked with:\n");425 for (ii = 0; ii < argc; ii++)426 ksft_print_msg("\t[%d]='%s\n'", ii, argv[ii]);427 }428 429 /* Check expected environment transferred. */430 if (!in_test || strcmp(in_test, "yes") != 0) {431 ksft_print_msg("no IN_TEST=yes in env\n");432 return 1;433 }434 435 /* Use the final argument as an exit code. */436 rc = atoi(argv[argc - 1]);437 exit(rc);438 } else {439 ksft_print_header();440 ksft_set_plan(TESTS_EXPECTED);441 prerequisites();442 if (verbose)443 envp[1] = "VERBOSE=1";444 rc = run_tests();445 if (rc > 0)446 printf("%d tests failed\n", rc);447 ksft_finished();448 }449 450 return rc;451}452