LXR linux/tools/testing/selftests/exec/execveat.c

   1/*
   2 * Copyright (c) 2014 Google, Inc.
   3 *
   4 * Licensed under the terms of the GNU GPL License version 2
   5 *
   6 * Selftests for execveat(2).
   7 */
   8
   9#define _GNU_SOURCE  /* to get O_PATH, AT_EMPTY_PATH */
  10#include <sys/sendfile.h>
  11#include <sys/stat.h>
  12#include <sys/syscall.h>
  13#include <sys/types.h>
  14#include <sys/wait.h>
  15#include <errno.h>
  16#include <fcntl.h>
  17#include <limits.h>
  18#include <stdio.h>
  19#include <stdlib.h>
  20#include <string.h>
  21#include <unistd.h>
  22
  23static char longpath[2 * PATH_MAX] = "";
  24static char *envp[] = { "IN_TEST=yes", NULL, NULL };
  25static char *argv[] = { "execveat", "99", NULL };
  26
  27static int execveat_(int fd, const char *path, char **argv, char **envp,
  28                     int flags)
  29{
  30#ifdef __NR_execveat
  31        return syscall(__NR_execveat, fd, path, argv, envp, flags);
  32#else
  33        errno = ENOSYS;
  34        return -1;
  35#endif
  36}
  37
  38#define check_execveat_fail(fd, path, flags, errno)     \
  39        _check_execveat_fail(fd, path, flags, errno, #errno)
  40static int _check_execveat_fail(int fd, const char *path, int flags,
  41                                int expected_errno, const char *errno_str)
  42{
  43        int rc;
  44
  45        errno = 0;
  46        printf("Check failure of execveat(%d, '%s', %d) with %s... ",
  47                fd, path?:"(null)", flags, errno_str);
  48        rc = execveat_(fd, path, argv, envp, flags);
  49
  50        if (rc > 0) {
  51                printf("[FAIL] (unexpected success from execveat(2))\n");
  52                return 1;
  53        }
  54        if (errno != expected_errno) {
  55                printf("[FAIL] (expected errno %d (%s) not %d (%s)\n",
  56                        expected_errno, strerror(expected_errno),
  57                        errno, strerror(errno));
  58                return 1;
  59        }
  60        printf("[OK]\n");
  61        return 0;
  62}
  63
  64static int check_execveat_invoked_rc(int fd, const char *path, int flags,
  65                                     int expected_rc, int expected_rc2)
  66{
  67        int status;
  68        int rc;
  69        pid_t child;
  70        int pathlen = path ? strlen(path) : 0;
  71
  72        if (pathlen > 40)
  73                printf("Check success of execveat(%d, '%.20s...%s', %d)... ",
  74                        fd, path, (path + pathlen - 20), flags);
  75        else
  76                printf("Check success of execveat(%d, '%s', %d)... ",
  77                        fd, path?:"(null)", flags);
  78        child = fork();
  79        if (child < 0) {
  80                printf("[FAIL] (fork() failed)\n");
  81                return 1;
  82        }
  83        if (child == 0) {
  84                /* Child: do execveat(). */
  85                rc = execveat_(fd, path, argv, envp, flags);
  86                printf("[FAIL]: execveat() failed, rc=%d errno=%d (%s)\n",
  87                        rc, errno, strerror(errno));
  88                exit(1);  /* should not reach here */
  89        }
  90        /* Parent: wait for & check child's exit status. */
  91        rc = waitpid(child, &status, 0);
  92        if (rc != child) {
  93                printf("[FAIL] (waitpid(%d,...) returned %d)\n", child, rc);
  94                return 1;
  95        }
  96        if (!WIFEXITED(status)) {
  97                printf("[FAIL] (child %d did not exit cleanly, status=%08x)\n",
  98                        child, status);
  99                return 1;
 100        }
 101        if ((WEXITSTATUS(status) != expected_rc) &&
 102            (WEXITSTATUS(status) != expected_rc2)) {
 103                printf("[FAIL] (child %d exited with %d not %d nor %d)\n",
 104                        child, WEXITSTATUS(status), expected_rc, expected_rc2);
 105                return 1;
 106        }
 107        printf("[OK]\n");
 108        return 0;
 109}
 110
 111static int check_execveat(int fd, const char *path, int flags)
 112{
 113        return check_execveat_invoked_rc(fd, path, flags, 99, 99);
 114}
 115
 116static char *concat(const char *left, const char *right)
 117{
 118        char *result = malloc(strlen(left) + strlen(right) + 1);
 119
 120        strcpy(result, left);
 121        strcat(result, right);
 122        return result;
 123}
 124
 125static int open_or_die(const char *filename, int flags)
 126{
 127        int fd = open(filename, flags);
 128
 129        if (fd < 0) {
 130                printf("Failed to open '%s'; "
 131                        "check prerequisites are available\n", filename);
 132                exit(1);
 133        }
 134        return fd;
 135}
 136
 137static void exe_cp(const char *src, const char *dest)
 138{
 139        int in_fd = open_or_die(src, O_RDONLY);
 140        int out_fd = open(dest, O_RDWR|O_CREAT|O_TRUNC, 0755);
 141        struct stat info;
 142
 143        fstat(in_fd, &info);
 144        sendfile(out_fd, in_fd, NULL, info.st_size);
 145        close(in_fd);
 146        close(out_fd);
 147}
 148
 149#define XX_DIR_LEN 200
 150static int check_execveat_pathmax(int dot_dfd, const char *src, int is_script)
 151{
 152        int fail = 0;
 153        int ii, count, len;
 154        char longname[XX_DIR_LEN + 1];
 155        int fd;
 156
 157        if (*longpath == '\0') {
 158                /* Create a filename close to PATH_MAX in length */
 159                memset(longname, 'x', XX_DIR_LEN - 1);
 160                longname[XX_DIR_LEN - 1] = '/';
 161                longname[XX_DIR_LEN] = '\0';
 162                count = (PATH_MAX - 3) / XX_DIR_LEN;
 163                for (ii = 0; ii < count; ii++) {
 164                        strcat(longpath, longname);
 165                        mkdir(longpath, 0755);
 166                }
 167                len = (PATH_MAX - 3) - (count * XX_DIR_LEN);
 168                if (len <= 0)
 169                        len = 1;
 170                memset(longname, 'y', len);
 171                longname[len] = '\0';
 172                strcat(longpath, longname);
 173        }
 174        exe_cp(src, longpath);
 175
 176        /*
 177         * Execute as a pre-opened file descriptor, which works whether this is
 178         * a script or not (because the interpreter sees a filename like
 179         * "/dev/fd/20").
 180         */
 181        fd = open(longpath, O_RDONLY);
 182        if (fd > 0) {
 183                printf("Invoke copy of '%s' via filename of length %zu:\n",
 184                        src, strlen(longpath));
 185                fail += check_execveat(fd, "", AT_EMPTY_PATH);
 186        } else {
 187                printf("Failed to open length %zu filename, errno=%d (%s)\n",
 188                        strlen(longpath), errno, strerror(errno));
 189                fail++;
 190        }
 191
 192        /*
 193         * Execute as a long pathname relative to ".".  If this is a script,
 194         * the interpreter will launch but fail to open the script because its
 195         * name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.
 196         *
 197         * The failure code is usually 127 (POSIX: "If a command is not found,
 198         * the exit status shall be 127."), but some systems give 126 (POSIX:
 199         * "If the command name is found, but it is not an executable utility,
 200         * the exit status shall be 126."), so allow either.
 201         */
 202        if (is_script)
 203                fail += check_execveat_invoked_rc(dot_dfd, longpath, 0,
 204                                                  127, 126);
 205        else
 206                fail += check_execveat(dot_dfd, longpath, 0);
 207
 208        return fail;
 209}
 210
 211static int run_tests(void)
 212{
 213        int fail = 0;
 214        char *fullname = realpath("execveat", NULL);
 215        char *fullname_script = realpath("script", NULL);
 216        char *fullname_symlink = concat(fullname, ".symlink");
 217        int subdir_dfd = open_or_die("subdir", O_DIRECTORY|O_RDONLY);
 218        int subdir_dfd_ephemeral = open_or_die("subdir.ephemeral",
 219                                               O_DIRECTORY|O_RDONLY);
 220        int dot_dfd = open_or_die(".", O_DIRECTORY|O_RDONLY);
 221        int dot_dfd_path = open_or_die(".", O_DIRECTORY|O_RDONLY|O_PATH);
 222        int dot_dfd_cloexec = open_or_die(".", O_DIRECTORY|O_RDONLY|O_CLOEXEC);
 223        int fd = open_or_die("execveat", O_RDONLY);
 224        int fd_path = open_or_die("execveat", O_RDONLY|O_PATH);
 225        int fd_symlink = open_or_die("execveat.symlink", O_RDONLY);
 226        int fd_denatured = open_or_die("execveat.denatured", O_RDONLY);
 227        int fd_denatured_path = open_or_die("execveat.denatured",
 228                                            O_RDONLY|O_PATH);
 229        int fd_script = open_or_die("script", O_RDONLY);
 230        int fd_ephemeral = open_or_die("execveat.ephemeral", O_RDONLY);
 231        int fd_ephemeral_path = open_or_die("execveat.path.ephemeral",
 232                                            O_RDONLY|O_PATH);
 233        int fd_script_ephemeral = open_or_die("script.ephemeral", O_RDONLY);
 234        int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);
 235        int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);
 236
 237        /* Check if we have execveat at all, and bail early if not */
 238        errno = 0;
 239        execveat_(-1, NULL, NULL, NULL, 0);
 240        if (errno == ENOSYS) {
 241                printf("[FAIL] ENOSYS calling execveat - no kernel support?\n");
 242                return 1;
 243        }
 244
 245        /* Change file position to confirm it doesn't affect anything */
 246        lseek(fd, 10, SEEK_SET);
 247
 248        /* Normal executable file: */
 249        /*   dfd + path */
 250        fail += check_execveat(subdir_dfd, "../execveat", 0);
 251        fail += check_execveat(dot_dfd, "execveat", 0);
 252        fail += check_execveat(dot_dfd_path, "execveat", 0);
 253        /*   absolute path */
 254        fail += check_execveat(AT_FDCWD, fullname, 0);
 255        /*   absolute path with nonsense dfd */
 256        fail += check_execveat(99, fullname, 0);
 257        /*   fd + no path */
 258        fail += check_execveat(fd, "", AT_EMPTY_PATH);
 259        /*   O_CLOEXEC fd + no path */
 260        fail += check_execveat(fd_cloexec, "", AT_EMPTY_PATH);
 261        /*   O_PATH fd */
 262        fail += check_execveat(fd_path, "", AT_EMPTY_PATH);
 263
 264        /* Mess with executable file that's already open: */
 265        /*   fd + no path to a file that's been renamed */
 266        rename("execveat.ephemeral", "execveat.moved");
 267        fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
 268        /*   fd + no path to a file that's been deleted */
 269        unlink("execveat.moved"); /* remove the file now fd open */
 270        fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
 271
 272        /* Mess with executable file that's already open with O_PATH */
 273        /*   fd + no path to a file that's been deleted */
 274        unlink("execveat.path.ephemeral");
 275        fail += check_execveat(fd_ephemeral_path, "", AT_EMPTY_PATH);
 276
 277        /* Invalid argument failures */
 278        fail += check_execveat_fail(fd, "", 0, ENOENT);
 279        fail += check_execveat_fail(fd, NULL, AT_EMPTY_PATH, EFAULT);
 280
 281        /* Symlink to executable file: */
 282        /*   dfd + path */
 283        fail += check_execveat(dot_dfd, "execveat.symlink", 0);
 284        fail += check_execveat(dot_dfd_path, "execveat.symlink", 0);
 285        /*   absolute path */
 286        fail += check_execveat(AT_FDCWD, fullname_symlink, 0);
 287        /*   fd + no path, even with AT_SYMLINK_NOFOLLOW (already followed) */
 288        fail += check_execveat(fd_symlink, "", AT_EMPTY_PATH);
 289        fail += check_execveat(fd_symlink, "",
 290                               AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
 291
 292        /* Symlink fails when AT_SYMLINK_NOFOLLOW set: */
 293        /*   dfd + path */
 294        fail += check_execveat_fail(dot_dfd, "execveat.symlink",
 295                                    AT_SYMLINK_NOFOLLOW, ELOOP);
 296        fail += check_execveat_fail(dot_dfd_path, "execveat.symlink",
 297                                    AT_SYMLINK_NOFOLLOW, ELOOP);
 298        /*   absolute path */
 299        fail += check_execveat_fail(AT_FDCWD, fullname_symlink,
 300                                    AT_SYMLINK_NOFOLLOW, ELOOP);
 301
 302        /* Shell script wrapping executable file: */
 303        /*   dfd + path */
 304        fail += check_execveat(subdir_dfd, "../script", 0);
 305        fail += check_execveat(dot_dfd, "script", 0);
 306        fail += check_execveat(dot_dfd_path, "script", 0);
 307        /*   absolute path */
 308        fail += check_execveat(AT_FDCWD, fullname_script, 0);
 309        /*   fd + no path */
 310        fail += check_execveat(fd_script, "", AT_EMPTY_PATH);
 311        fail += check_execveat(fd_script, "",
 312                               AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
 313        /*   O_CLOEXEC fd fails for a script (as script file inaccessible) */
 314        fail += check_execveat_fail(fd_script_cloexec, "", AT_EMPTY_PATH,
 315                                    ENOENT);
 316        fail += check_execveat_fail(dot_dfd_cloexec, "script", 0, ENOENT);
 317
 318        /* Mess with script file that's already open: */
 319        /*   fd + no path to a file that's been renamed */
 320        rename("script.ephemeral", "script.moved");
 321        fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
 322        /*   fd + no path to a file that's been deleted */
 323        unlink("script.moved"); /* remove the file while fd open */
 324        fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
 325
 326        /* Rename a subdirectory in the path: */
 327        rename("subdir.ephemeral", "subdir.moved");
 328        fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
 329        fail += check_execveat(subdir_dfd_ephemeral, "script", 0);
 330        /* Remove the subdir and its contents */
 331        unlink("subdir.moved/script");
 332        unlink("subdir.moved");
 333        /* Shell loads via deleted subdir OK because name starts with .. */
 334        fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
 335        fail += check_execveat_fail(subdir_dfd_ephemeral, "script", 0, ENOENT);
 336
 337        /* Flag values other than AT_SYMLINK_NOFOLLOW => EINVAL */
 338        fail += check_execveat_fail(dot_dfd, "execveat", 0xFFFF, EINVAL);
 339        /* Invalid path => ENOENT */
 340        fail += check_execveat_fail(dot_dfd, "no-such-file", 0, ENOENT);
 341        fail += check_execveat_fail(dot_dfd_path, "no-such-file", 0, ENOENT);
 342        fail += check_execveat_fail(AT_FDCWD, "no-such-file", 0, ENOENT);
 343        /* Attempt to execute directory => EACCES */
 344        fail += check_execveat_fail(dot_dfd, "", AT_EMPTY_PATH, EACCES);
 345        /* Attempt to execute non-executable => EACCES */
 346        fail += check_execveat_fail(dot_dfd, "Makefile", 0, EACCES);
 347        fail += check_execveat_fail(fd_denatured, "", AT_EMPTY_PATH, EACCES);
 348        fail += check_execveat_fail(fd_denatured_path, "", AT_EMPTY_PATH,
 349                                    EACCES);
 350        /* Attempt to execute nonsense FD => EBADF */
 351        fail += check_execveat_fail(99, "", AT_EMPTY_PATH, EBADF);
 352        fail += check_execveat_fail(99, "execveat", 0, EBADF);
 353        /* Attempt to execute relative to non-directory => ENOTDIR */
 354        fail += check_execveat_fail(fd, "execveat", 0, ENOTDIR);
 355
 356        fail += check_execveat_pathmax(dot_dfd, "execveat", 0);
 357        fail += check_execveat_pathmax(dot_dfd, "script", 1);
 358        return fail;
 359}
 360
 361static void prerequisites(void)
 362{
 363        int fd;
 364        const char *script = "#!/bin/sh\nexit $*\n";
 365
 366        /* Create ephemeral copies of files */
 367        exe_cp("execveat", "execveat.ephemeral");
 368        exe_cp("execveat", "execveat.path.ephemeral");
 369        exe_cp("script", "script.ephemeral");
 370        mkdir("subdir.ephemeral", 0755);
 371
 372        fd = open("subdir.ephemeral/script", O_RDWR|O_CREAT|O_TRUNC, 0755);
 373        write(fd, script, strlen(script));
 374        close(fd);
 375}
 376
 377int main(int argc, char **argv)
 378{
 379        int ii;
 380        int rc;
 381        const char *verbose = getenv("VERBOSE");
 382
 383        if (argc >= 2) {
 384                /* If we are invoked with an argument, don't run tests. */
 385                const char *in_test = getenv("IN_TEST");
 386
 387                if (verbose) {
 388                        printf("  invoked with:");
 389                        for (ii = 0; ii < argc; ii++)
 390                                printf(" [%d]='%s'", ii, argv[ii]);
 391                        printf("\n");
 392                }
 393
 394                /* Check expected environment transferred. */
 395                if (!in_test || strcmp(in_test, "yes") != 0) {
 396                        printf("[FAIL] (no IN_TEST=yes in env)\n");
 397                        return 1;
 398                }
 399
 400                /* Use the final argument as an exit code. */
 401                rc = atoi(argv[argc - 1]);
 402                fflush(stdout);
 403        } else {
 404                prerequisites();
 405                if (verbose)
 406                        envp[1] = "VERBOSE=1";
 407                rc = run_tests();
 408                if (rc > 0)
 409                        printf("%d tests failed\n", rc);
 410        }
 411        return rc;
 412}
 413