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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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 54#define TEST_NAME_LEN (PATH_MAX * 4)
#define CHECK_COMM "CHECK_COMM"
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 200static 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 check_execveat_comm(int fd, char *argv0, char *expected){ char buf[128], *old_env, *old_argv0; int ret;
snprintf(buf, sizeof(buf), CHECK_COMM "=%s", expected);
old_env = envp[1]; envp[1] = buf;
old_argv0 = argv[0]; argv[0] = argv0;
ksft_print_msg("Check execveat(AT_EMPTY_PATH)'s comm is %s\n", expected); ret = check_execveat_invoked_rc(fd, "", AT_EMPTY_PATH, 0, 0);
envp[1] = old_env; argv[0] = old_argv0;
return ret;}
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);
/* /proc/pid/comm gives filename by default */ fail += check_execveat_comm(fd, "sentinel", "execveat"); /* /proc/pid/comm gives argv[0] when invoked via link */ fail += check_execveat_comm(fd_symlink, "sentinel", "execveat"); /* /proc/pid/comm gives filename if NULL is passed */ fail += check_execveat_comm(fd, NULL, "execveat");
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"); const char *check_comm = getenv(CHECK_COMM);
if (argc >= 2 || check_comm) { /* * If we are invoked with an argument, or no arguments but a * command to check, 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]); }
/* If the tests wanted us to check the command, do so. */ if (check_comm) { /* TASK_COMM_LEN == 16 */ char buf[32]; int fd, ret;
fd = open("/proc/self/comm", O_RDONLY); if (fd < 0) { ksft_perror("open() comm failed"); exit(1); }
ret = read(fd, buf, sizeof(buf)); if (ret < 0) { ksft_perror("read() comm failed"); close(fd); exit(1); } close(fd);
// trim off the \n buf[ret-1] = 0;
if (strcmp(buf, check_comm)) { ksft_print_msg("bad comm, got: %s expected: %s\n", buf, check_comm); exit(1); }
exit(0); }
/* 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;}