Loading...
Note: File does not exist in v3.15.
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 root_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 char *cwd = getcwd(NULL, 0);
160
161 if (!cwd) {
162 printf("Failed to getcwd(), errno=%d (%s)\n",
163 errno, strerror(errno));
164 return 2;
165 }
166 strcpy(longpath, cwd);
167 strcat(longpath, "/");
168 memset(longname, 'x', XX_DIR_LEN - 1);
169 longname[XX_DIR_LEN - 1] = '/';
170 longname[XX_DIR_LEN] = '\0';
171 count = (PATH_MAX - 3 - strlen(cwd)) / XX_DIR_LEN;
172 for (ii = 0; ii < count; ii++) {
173 strcat(longpath, longname);
174 mkdir(longpath, 0755);
175 }
176 len = (PATH_MAX - 3 - strlen(cwd)) - (count * XX_DIR_LEN);
177 if (len <= 0)
178 len = 1;
179 memset(longname, 'y', len);
180 longname[len] = '\0';
181 strcat(longpath, longname);
182 free(cwd);
183 }
184 exe_cp(src, longpath);
185
186 /*
187 * Execute as a pre-opened file descriptor, which works whether this is
188 * a script or not (because the interpreter sees a filename like
189 * "/dev/fd/20").
190 */
191 fd = open(longpath, O_RDONLY);
192 if (fd > 0) {
193 printf("Invoke copy of '%s' via filename of length %zu:\n",
194 src, strlen(longpath));
195 fail += check_execveat(fd, "", AT_EMPTY_PATH);
196 } else {
197 printf("Failed to open length %zu filename, errno=%d (%s)\n",
198 strlen(longpath), errno, strerror(errno));
199 fail++;
200 }
201
202 /*
203 * Execute as a long pathname relative to "/". If this is a script,
204 * the interpreter will launch but fail to open the script because its
205 * name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.
206 *
207 * The failure code is usually 127 (POSIX: "If a command is not found,
208 * the exit status shall be 127."), but some systems give 126 (POSIX:
209 * "If the command name is found, but it is not an executable utility,
210 * the exit status shall be 126."), so allow either.
211 */
212 if (is_script)
213 fail += check_execveat_invoked_rc(root_dfd, longpath + 1, 0,
214 127, 126);
215 else
216 fail += check_execveat(root_dfd, longpath + 1, 0);
217
218 return fail;
219}
220
221static int run_tests(void)
222{
223 int fail = 0;
224 char *fullname = realpath("execveat", NULL);
225 char *fullname_script = realpath("script", NULL);
226 char *fullname_symlink = concat(fullname, ".symlink");
227 int subdir_dfd = open_or_die("subdir", O_DIRECTORY|O_RDONLY);
228 int subdir_dfd_ephemeral = open_or_die("subdir.ephemeral",
229 O_DIRECTORY|O_RDONLY);
230 int dot_dfd = open_or_die(".", O_DIRECTORY|O_RDONLY);
231 int root_dfd = open_or_die("/", O_DIRECTORY|O_RDONLY);
232 int dot_dfd_path = open_or_die(".", O_DIRECTORY|O_RDONLY|O_PATH);
233 int dot_dfd_cloexec = open_or_die(".", O_DIRECTORY|O_RDONLY|O_CLOEXEC);
234 int fd = open_or_die("execveat", O_RDONLY);
235 int fd_path = open_or_die("execveat", O_RDONLY|O_PATH);
236 int fd_symlink = open_or_die("execveat.symlink", O_RDONLY);
237 int fd_denatured = open_or_die("execveat.denatured", O_RDONLY);
238 int fd_denatured_path = open_or_die("execveat.denatured",
239 O_RDONLY|O_PATH);
240 int fd_script = open_or_die("script", O_RDONLY);
241 int fd_ephemeral = open_or_die("execveat.ephemeral", O_RDONLY);
242 int fd_ephemeral_path = open_or_die("execveat.path.ephemeral",
243 O_RDONLY|O_PATH);
244 int fd_script_ephemeral = open_or_die("script.ephemeral", O_RDONLY);
245 int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);
246 int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);
247
248 /* Check if we have execveat at all, and bail early if not */
249 errno = 0;
250 execveat_(-1, NULL, NULL, NULL, 0);
251 if (errno == ENOSYS) {
252 printf("[FAIL] ENOSYS calling execveat - no kernel support?\n");
253 return 1;
254 }
255
256 /* Change file position to confirm it doesn't affect anything */
257 lseek(fd, 10, SEEK_SET);
258
259 /* Normal executable file: */
260 /* dfd + path */
261 fail += check_execveat(subdir_dfd, "../execveat", 0);
262 fail += check_execveat(dot_dfd, "execveat", 0);
263 fail += check_execveat(dot_dfd_path, "execveat", 0);
264 /* absolute path */
265 fail += check_execveat(AT_FDCWD, fullname, 0);
266 /* absolute path with nonsense dfd */
267 fail += check_execveat(99, fullname, 0);
268 /* fd + no path */
269 fail += check_execveat(fd, "", AT_EMPTY_PATH);
270 /* O_CLOEXEC fd + no path */
271 fail += check_execveat(fd_cloexec, "", AT_EMPTY_PATH);
272 /* O_PATH fd */
273 fail += check_execveat(fd_path, "", AT_EMPTY_PATH);
274
275 /* Mess with executable file that's already open: */
276 /* fd + no path to a file that's been renamed */
277 rename("execveat.ephemeral", "execveat.moved");
278 fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
279 /* fd + no path to a file that's been deleted */
280 unlink("execveat.moved"); /* remove the file now fd open */
281 fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
282
283 /* Mess with executable file that's already open with O_PATH */
284 /* fd + no path to a file that's been deleted */
285 unlink("execveat.path.ephemeral");
286 fail += check_execveat(fd_ephemeral_path, "", AT_EMPTY_PATH);
287
288 /* Invalid argument failures */
289 fail += check_execveat_fail(fd, "", 0, ENOENT);
290 fail += check_execveat_fail(fd, NULL, AT_EMPTY_PATH, EFAULT);
291
292 /* Symlink to executable file: */
293 /* dfd + path */
294 fail += check_execveat(dot_dfd, "execveat.symlink", 0);
295 fail += check_execveat(dot_dfd_path, "execveat.symlink", 0);
296 /* absolute path */
297 fail += check_execveat(AT_FDCWD, fullname_symlink, 0);
298 /* fd + no path, even with AT_SYMLINK_NOFOLLOW (already followed) */
299 fail += check_execveat(fd_symlink, "", AT_EMPTY_PATH);
300 fail += check_execveat(fd_symlink, "",
301 AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
302
303 /* Symlink fails when AT_SYMLINK_NOFOLLOW set: */
304 /* dfd + path */
305 fail += check_execveat_fail(dot_dfd, "execveat.symlink",
306 AT_SYMLINK_NOFOLLOW, ELOOP);
307 fail += check_execveat_fail(dot_dfd_path, "execveat.symlink",
308 AT_SYMLINK_NOFOLLOW, ELOOP);
309 /* absolute path */
310 fail += check_execveat_fail(AT_FDCWD, fullname_symlink,
311 AT_SYMLINK_NOFOLLOW, ELOOP);
312
313 /* Shell script wrapping executable file: */
314 /* dfd + path */
315 fail += check_execveat(subdir_dfd, "../script", 0);
316 fail += check_execveat(dot_dfd, "script", 0);
317 fail += check_execveat(dot_dfd_path, "script", 0);
318 /* absolute path */
319 fail += check_execveat(AT_FDCWD, fullname_script, 0);
320 /* fd + no path */
321 fail += check_execveat(fd_script, "", AT_EMPTY_PATH);
322 fail += check_execveat(fd_script, "",
323 AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
324 /* O_CLOEXEC fd fails for a script (as script file inaccessible) */
325 fail += check_execveat_fail(fd_script_cloexec, "", AT_EMPTY_PATH,
326 ENOENT);
327 fail += check_execveat_fail(dot_dfd_cloexec, "script", 0, ENOENT);
328
329 /* Mess with script file that's already open: */
330 /* fd + no path to a file that's been renamed */
331 rename("script.ephemeral", "script.moved");
332 fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
333 /* fd + no path to a file that's been deleted */
334 unlink("script.moved"); /* remove the file while fd open */
335 fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
336
337 /* Rename a subdirectory in the path: */
338 rename("subdir.ephemeral", "subdir.moved");
339 fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
340 fail += check_execveat(subdir_dfd_ephemeral, "script", 0);
341 /* Remove the subdir and its contents */
342 unlink("subdir.moved/script");
343 unlink("subdir.moved");
344 /* Shell loads via deleted subdir OK because name starts with .. */
345 fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
346 fail += check_execveat_fail(subdir_dfd_ephemeral, "script", 0, ENOENT);
347
348 /* Flag values other than AT_SYMLINK_NOFOLLOW => EINVAL */
349 fail += check_execveat_fail(dot_dfd, "execveat", 0xFFFF, EINVAL);
350 /* Invalid path => ENOENT */
351 fail += check_execveat_fail(dot_dfd, "no-such-file", 0, ENOENT);
352 fail += check_execveat_fail(dot_dfd_path, "no-such-file", 0, ENOENT);
353 fail += check_execveat_fail(AT_FDCWD, "no-such-file", 0, ENOENT);
354 /* Attempt to execute directory => EACCES */
355 fail += check_execveat_fail(dot_dfd, "", AT_EMPTY_PATH, EACCES);
356 /* Attempt to execute non-executable => EACCES */
357 fail += check_execveat_fail(dot_dfd, "Makefile", 0, EACCES);
358 fail += check_execveat_fail(fd_denatured, "", AT_EMPTY_PATH, EACCES);
359 fail += check_execveat_fail(fd_denatured_path, "", AT_EMPTY_PATH,
360 EACCES);
361 /* Attempt to execute nonsense FD => EBADF */
362 fail += check_execveat_fail(99, "", AT_EMPTY_PATH, EBADF);
363 fail += check_execveat_fail(99, "execveat", 0, EBADF);
364 /* Attempt to execute relative to non-directory => ENOTDIR */
365 fail += check_execveat_fail(fd, "execveat", 0, ENOTDIR);
366
367 fail += check_execveat_pathmax(root_dfd, "execveat", 0);
368 fail += check_execveat_pathmax(root_dfd, "script", 1);
369 return fail;
370}
371
372static void prerequisites(void)
373{
374 int fd;
375 const char *script = "#!/bin/sh\nexit $*\n";
376
377 /* Create ephemeral copies of files */
378 exe_cp("execveat", "execveat.ephemeral");
379 exe_cp("execveat", "execveat.path.ephemeral");
380 exe_cp("script", "script.ephemeral");
381 mkdir("subdir.ephemeral", 0755);
382
383 fd = open("subdir.ephemeral/script", O_RDWR|O_CREAT|O_TRUNC, 0755);
384 write(fd, script, strlen(script));
385 close(fd);
386}
387
388int main(int argc, char **argv)
389{
390 int ii;
391 int rc;
392 const char *verbose = getenv("VERBOSE");
393
394 if (argc >= 2) {
395 /* If we are invoked with an argument, don't run tests. */
396 const char *in_test = getenv("IN_TEST");
397
398 if (verbose) {
399 printf(" invoked with:");
400 for (ii = 0; ii < argc; ii++)
401 printf(" [%d]='%s'", ii, argv[ii]);
402 printf("\n");
403 }
404
405 /* Check expected environment transferred. */
406 if (!in_test || strcmp(in_test, "yes") != 0) {
407 printf("[FAIL] (no IN_TEST=yes in env)\n");
408 return 1;
409 }
410
411 /* Use the final argument as an exit code. */
412 rc = atoi(argv[argc - 1]);
413 fflush(stdout);
414 } else {
415 prerequisites();
416 if (verbose)
417 envp[1] = "VERBOSE=1";
418 rc = run_tests();
419 if (rc > 0)
420 printf("%d tests failed\n", rc);
421 }
422 return rc;
423}