// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2014 Google, Inc.
*
* Selftests for execveat(2).
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE /* to get O_PATH, AT_EMPTY_PATH */
#endif
#include <sys/sendfile.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "../kselftest.h"
#define TESTS_EXPECTED 51
#define TEST_NAME_LEN (PATH_MAX * 4)
static char longpath[2 * PATH_MAX] = "";
static char *envp[] = { "IN_TEST=yes", NULL, NULL };
static char *argv[] = { "execveat", "99", NULL };
static int execveat_(int fd, const char *path, char **argv, char **envp,
int flags)
{
#ifdef __NR_execveat
return syscall(__NR_execveat, fd, path, argv, envp, flags);
#else
errno = ENOSYS;
return -1;
#endif
}
#define check_execveat_fail(fd, path, flags, errno) \
_check_execveat_fail(fd, path, flags, errno, #errno)
static int _check_execveat_fail(int fd, const char *path, int flags,
int expected_errno, const char *errno_str)
{
char test_name[TEST_NAME_LEN];
int rc;
errno = 0;
snprintf(test_name, sizeof(test_name),
"Check failure of execveat(%d, '%s', %d) with %s",
fd, path?:"(null)", flags, errno_str);
rc = execveat_(fd, path, argv, envp, flags);
if (rc > 0) {
ksft_print_msg("unexpected success from execveat(2)\n");
ksft_test_result_fail("%s\n", test_name);
return 1;
}
if (errno != expected_errno) {
ksft_print_msg("expected errno %d (%s) not %d (%s)\n",
expected_errno, strerror(expected_errno),
errno, strerror(errno));
ksft_test_result_fail("%s\n", test_name);
return 1;
}
ksft_test_result_pass("%s\n", test_name);
return 0;
}
static int check_execveat_invoked_rc(int fd, const char *path, int flags,
int expected_rc, int expected_rc2)
{
char test_name[TEST_NAME_LEN];
int status;
int rc;
pid_t child;
int pathlen = path ? strlen(path) : 0;
if (pathlen > 40)
snprintf(test_name, sizeof(test_name),
"Check success of execveat(%d, '%.20s...%s', %d)... ",
fd, path, (path + pathlen - 20), flags);
else
snprintf(test_name, sizeof(test_name),
"Check success of execveat(%d, '%s', %d)... ",
fd, path?:"(null)", flags);
child = fork();
if (child < 0) {
ksft_perror("fork() failed");
ksft_test_result_fail("%s\n", test_name);
return 1;
}
if (child == 0) {
/* Child: do execveat(). */
rc = execveat_(fd, path, argv, envp, flags);
ksft_print_msg("child execveat() failed, rc=%d errno=%d (%s)\n",
rc, errno, strerror(errno));
exit(errno);
}
/* Parent: wait for & check child's exit status. */
rc = waitpid(child, &status, 0);
if (rc != child) {
ksft_print_msg("waitpid(%d,...) returned %d\n", child, rc);
ksft_test_result_fail("%s\n", test_name);
return 1;
}
if (!WIFEXITED(status)) {
ksft_print_msg("child %d did not exit cleanly, status=%08x\n",
child, status);
ksft_test_result_fail("%s\n", test_name);
return 1;
}
if ((WEXITSTATUS(status) != expected_rc) &&
(WEXITSTATUS(status) != expected_rc2)) {
ksft_print_msg("child %d exited with %d neither %d nor %d\n",
child, WEXITSTATUS(status), expected_rc,
expected_rc2);
ksft_test_result_fail("%s\n", test_name);
return 1;
}
ksft_test_result_pass("%s\n", test_name);
return 0;
}
static int check_execveat(int fd, const char *path, int flags)
{
return check_execveat_invoked_rc(fd, path, flags, 99, 99);
}
static char *concat(const char *left, const char *right)
{
char *result = malloc(strlen(left) + strlen(right) + 1);
strcpy(result, left);
strcat(result, right);
return result;
}
static int open_or_die(const char *filename, int flags)
{
int fd = open(filename, flags);
if (fd < 0)
ksft_exit_fail_msg("Failed to open '%s'; "
"check prerequisites are available\n", filename);
return fd;
}
static void exe_cp(const char *src, const char *dest)
{
int in_fd = open_or_die(src, O_RDONLY);
int out_fd = open(dest, O_RDWR|O_CREAT|O_TRUNC, 0755);
struct stat info;
fstat(in_fd, &info);
sendfile(out_fd, in_fd, NULL, info.st_size);
close(in_fd);
close(out_fd);
}
#define XX_DIR_LEN 200
static int check_execveat_pathmax(int root_dfd, const char *src, int is_script)
{
int fail = 0;
int ii, count, len;
char longname[XX_DIR_LEN + 1];
int fd;
if (*longpath == '\0') {
/* Create a filename close to PATH_MAX in length */
char *cwd = getcwd(NULL, 0);
if (!cwd) {
ksft_perror("Failed to getcwd()");
return 2;
}
strcpy(longpath, cwd);
strcat(longpath, "/");
memset(longname, 'x', XX_DIR_LEN - 1);
longname[XX_DIR_LEN - 1] = '/';
longname[XX_DIR_LEN] = '\0';
count = (PATH_MAX - 3 - strlen(cwd)) / XX_DIR_LEN;
for (ii = 0; ii < count; ii++) {
strcat(longpath, longname);
mkdir(longpath, 0755);
}
len = (PATH_MAX - 3 - strlen(cwd)) - (count * XX_DIR_LEN);
if (len <= 0)
len = 1;
memset(longname, 'y', len);
longname[len] = '\0';
strcat(longpath, longname);
free(cwd);
}
exe_cp(src, longpath);
/*
* Execute as a pre-opened file descriptor, which works whether this is
* a script or not (because the interpreter sees a filename like
* "/dev/fd/20").
*/
fd = open(longpath, O_RDONLY);
if (fd > 0) {
ksft_print_msg("Invoke copy of '%s' via filename of length %zu:\n",
src, strlen(longpath));
fail += check_execveat(fd, "", AT_EMPTY_PATH);
} else {
ksft_print_msg("Failed to open length %zu filename, errno=%d (%s)\n",
strlen(longpath), errno, strerror(errno));
fail++;
}
/*
* Execute as a long pathname relative to "/". If this is a script,
* the interpreter will launch but fail to open the script because its
* name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.
*
* The failure code is usually 127 (POSIX: "If a command is not found,
* the exit status shall be 127."), but some systems give 126 (POSIX:
* "If the command name is found, but it is not an executable utility,
* the exit status shall be 126."), so allow either.
*/
if (is_script) {
ksft_print_msg("Invoke script via root_dfd and relative filename\n");
fail += check_execveat_invoked_rc(root_dfd, longpath + 1, 0,
127, 126);
} else {
ksft_print_msg("Invoke exec via root_dfd and relative filename\n");
fail += check_execveat(root_dfd, longpath + 1, 0);
}
return fail;
}
static int run_tests(void)
{
int fail = 0;
char *fullname = realpath("execveat", NULL);
char *fullname_script = realpath("script", NULL);
char *fullname_symlink = concat(fullname, ".symlink");
int subdir_dfd = open_or_die("subdir", O_DIRECTORY|O_RDONLY);
int subdir_dfd_ephemeral = open_or_die("subdir.ephemeral",
O_DIRECTORY|O_RDONLY);
int dot_dfd = open_or_die(".", O_DIRECTORY|O_RDONLY);
int root_dfd = open_or_die("/", O_DIRECTORY|O_RDONLY);
int dot_dfd_path = open_or_die(".", O_DIRECTORY|O_RDONLY|O_PATH);
int dot_dfd_cloexec = open_or_die(".", O_DIRECTORY|O_RDONLY|O_CLOEXEC);
int fd = open_or_die("execveat", O_RDONLY);
int fd_path = open_or_die("execveat", O_RDONLY|O_PATH);
int fd_symlink = open_or_die("execveat.symlink", O_RDONLY);
int fd_denatured = open_or_die("execveat.denatured", O_RDONLY);
int fd_denatured_path = open_or_die("execveat.denatured",
O_RDONLY|O_PATH);
int fd_script = open_or_die("script", O_RDONLY);
int fd_ephemeral = open_or_die("execveat.ephemeral", O_RDONLY);
int fd_ephemeral_path = open_or_die("execveat.path.ephemeral",
O_RDONLY|O_PATH);
int fd_script_ephemeral = open_or_die("script.ephemeral", O_RDONLY);
int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);
int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);
/* Check if we have execveat at all, and bail early if not */
errno = 0;
execveat_(-1, NULL, NULL, NULL, 0);
if (errno == ENOSYS) {
ksft_exit_skip(
"ENOSYS calling execveat - no kernel support?\n");
}
/* Change file position to confirm it doesn't affect anything */
lseek(fd, 10, SEEK_SET);
/* Normal executable file: */
/* dfd + path */
fail += check_execveat(subdir_dfd, "../execveat", 0);
fail += check_execveat(dot_dfd, "execveat", 0);
fail += check_execveat(dot_dfd_path, "execveat", 0);
/* absolute path */
fail += check_execveat(AT_FDCWD, fullname, 0);
/* absolute path with nonsense dfd */
fail += check_execveat(99, fullname, 0);
/* fd + no path */
fail += check_execveat(fd, "", AT_EMPTY_PATH);
/* O_CLOEXEC fd + no path */
fail += check_execveat(fd_cloexec, "", AT_EMPTY_PATH);
/* O_PATH fd */
fail += check_execveat(fd_path, "", AT_EMPTY_PATH);
/* Mess with executable file that's already open: */
/* fd + no path to a file that's been renamed */
rename("execveat.ephemeral", "execveat.moved");
fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
/* fd + no path to a file that's been deleted */
unlink("execveat.moved"); /* remove the file now fd open */
fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
/* Mess with executable file that's already open with O_PATH */
/* fd + no path to a file that's been deleted */
unlink("execveat.path.ephemeral");
fail += check_execveat(fd_ephemeral_path, "", AT_EMPTY_PATH);
/* Invalid argument failures */
fail += check_execveat_fail(fd, "", 0, ENOENT);
fail += check_execveat_fail(fd, NULL, AT_EMPTY_PATH, EFAULT);
/* Symlink to executable file: */
/* dfd + path */
fail += check_execveat(dot_dfd, "execveat.symlink", 0);
fail += check_execveat(dot_dfd_path, "execveat.symlink", 0);
/* absolute path */
fail += check_execveat(AT_FDCWD, fullname_symlink, 0);
/* fd + no path, even with AT_SYMLINK_NOFOLLOW (already followed) */
fail += check_execveat(fd_symlink, "", AT_EMPTY_PATH);
fail += check_execveat(fd_symlink, "",
AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
/* Symlink fails when AT_SYMLINK_NOFOLLOW set: */
/* dfd + path */
fail += check_execveat_fail(dot_dfd, "execveat.symlink",
AT_SYMLINK_NOFOLLOW, ELOOP);
fail += check_execveat_fail(dot_dfd_path, "execveat.symlink",
AT_SYMLINK_NOFOLLOW, ELOOP);
/* absolute path */
fail += check_execveat_fail(AT_FDCWD, fullname_symlink,
AT_SYMLINK_NOFOLLOW, ELOOP);
/* Non-regular file failure */
fail += check_execveat_fail(dot_dfd, "pipe", 0, EACCES);
unlink("pipe");
/* Shell script wrapping executable file: */
/* dfd + path */
fail += check_execveat(subdir_dfd, "../script", 0);
fail += check_execveat(dot_dfd, "script", 0);
fail += check_execveat(dot_dfd_path, "script", 0);
/* absolute path */
fail += check_execveat(AT_FDCWD, fullname_script, 0);
/* fd + no path */
fail += check_execveat(fd_script, "", AT_EMPTY_PATH);
fail += check_execveat(fd_script, "",
AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
/* O_CLOEXEC fd fails for a script (as script file inaccessible) */
fail += check_execveat_fail(fd_script_cloexec, "", AT_EMPTY_PATH,
ENOENT);
fail += check_execveat_fail(dot_dfd_cloexec, "script", 0, ENOENT);
/* Mess with script file that's already open: */
/* fd + no path to a file that's been renamed */
rename("script.ephemeral", "script.moved");
fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
/* fd + no path to a file that's been deleted */
unlink("script.moved"); /* remove the file while fd open */
fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
/* Rename a subdirectory in the path: */
rename("subdir.ephemeral", "subdir.moved");
fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
fail += check_execveat(subdir_dfd_ephemeral, "script", 0);
/* Remove the subdir and its contents */
unlink("subdir.moved/script");
unlink("subdir.moved");
/* Shell loads via deleted subdir OK because name starts with .. */
fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
fail += check_execveat_fail(subdir_dfd_ephemeral, "script", 0, ENOENT);
/* Flag values other than AT_SYMLINK_NOFOLLOW => EINVAL */
fail += check_execveat_fail(dot_dfd, "execveat", 0xFFFF, EINVAL);
/* Invalid path => ENOENT */
fail += check_execveat_fail(dot_dfd, "no-such-file", 0, ENOENT);
fail += check_execveat_fail(dot_dfd_path, "no-such-file", 0, ENOENT);
fail += check_execveat_fail(AT_FDCWD, "no-such-file", 0, ENOENT);
/* Attempt to execute directory => EACCES */
fail += check_execveat_fail(dot_dfd, "", AT_EMPTY_PATH, EACCES);
/* Attempt to execute non-executable => EACCES */
fail += check_execveat_fail(dot_dfd, "Makefile", 0, EACCES);
fail += check_execveat_fail(fd_denatured, "", AT_EMPTY_PATH, EACCES);
fail += check_execveat_fail(fd_denatured_path, "", AT_EMPTY_PATH,
EACCES);
/* Attempt to execute nonsense FD => EBADF */
fail += check_execveat_fail(99, "", AT_EMPTY_PATH, EBADF);
fail += check_execveat_fail(99, "execveat", 0, EBADF);
/* Attempt to execute relative to non-directory => ENOTDIR */
fail += check_execveat_fail(fd, "execveat", 0, ENOTDIR);
fail += check_execveat_pathmax(root_dfd, "execveat", 0);
fail += check_execveat_pathmax(root_dfd, "script", 1);
return fail;
}
static void prerequisites(void)
{
int fd;
const char *script = "#!/bin/bash\nexit $*\n";
/* Create ephemeral copies of files */
exe_cp("execveat", "execveat.ephemeral");
exe_cp("execveat", "execveat.path.ephemeral");
exe_cp("script", "script.ephemeral");
mkdir("subdir.ephemeral", 0755);
fd = open("subdir.ephemeral/script", O_RDWR|O_CREAT|O_TRUNC, 0755);
write(fd, script, strlen(script));
close(fd);
mkfifo("pipe", 0755);
}
int main(int argc, char **argv)
{
int ii;
int rc;
const char *verbose = getenv("VERBOSE");
if (argc >= 2) {
/* If we are invoked with an argument, don't run tests. */
const char *in_test = getenv("IN_TEST");
if (verbose) {
ksft_print_msg("invoked with:\n");
for (ii = 0; ii < argc; ii++)
ksft_print_msg("\t[%d]='%s\n'", ii, argv[ii]);
}
/* Check expected environment transferred. */
if (!in_test || strcmp(in_test, "yes") != 0) {
ksft_print_msg("no IN_TEST=yes in env\n");
return 1;
}
/* Use the final argument as an exit code. */
rc = atoi(argv[argc - 1]);
exit(rc);
} else {
ksft_print_header();
ksft_set_plan(TESTS_EXPECTED);
prerequisites();
if (verbose)
envp[1] = "VERBOSE=1";
rc = run_tests();
if (rc > 0)
printf("%d tests failed\n", rc);
ksft_finished();
}
return rc;
}
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