#define _GNU_SOURCE /* exec_variants.c -- Linux parity for the less-common exec entry points. */#include <errno.h>#include <fcntl.h>#include <limits.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/stat.h>#include <unistd.h> static int find_self(const char *argv0, char *out, size_t out_len) { if (strchr(argv0, '/')) { if (strlen(argv0) + 1 > out_len) { errno = ENAMETOOLONG; return -1; } memcpy(out, argv0, strlen(argv0) + 1); return 0; } const char *path = getenv("PATH"); if (!path) path = "/bin:/usr/bin"; for (const char *segment = path;;) { const char *colon = strchr(segment, ':'); size_t dir_len = colon ? (size_t)(colon - segment) : strlen(segment); int written = dir_len ? snprintf(out, out_len, "%.*s/%s", (int)dir_len, segment, argv0) : snprintf(out, out_len, "./%s", argv0); if (written >= 0 && (size_t)written < out_len && access(out, R_OK) == 0) return 0; if (!colon) break; segment = colon + 1; } errno = ENOENT; return -1;} static int copy_to_unlinked_fd(const char *source_path, int *out_fd) { int source = open(source_path, O_RDONLY); if (source < 0) return -1; char copy_path[] = "/tmp/agentos-fexecve-XXXXXX"; int copy = mkstemp(copy_path); if (copy < 0) { close(source); return -1; } char buffer[8192]; for (;;) { ssize_t length = read(source, buffer, sizeof(buffer)); if (length < 0) goto fail; if (length == 0) break; for (ssize_t offset = 0; offset < length;) { ssize_t written = write(copy, buffer + offset, (size_t)(length - offset)); if (written < 0) goto fail; offset += written; } } if (close(source) != 0) { source = -1; goto fail; } source = -1; if (fchmod(copy, 0700) != 0) { goto fail; } if (close(copy) != 0) { copy = -1; goto fail; } copy = open(copy_path, O_RDONLY); if (copy < 0) goto fail; if (unlink(copy_path) != 0) goto fail; if (fcntl(copy, F_SETFD, FD_CLOEXEC) != 0) goto fail; *out_fd = copy; return 0; fail: { int saved_errno = errno; if (source >= 0) close(source); if (copy >= 0) close(copy); unlink(copy_path); errno = saved_errno; return -1; }} static int create_script(char *path_template, const char *contents) { int fd = mkstemp(path_template); if (fd < 0) return -1; size_t length = strlen(contents); for (size_t offset = 0; offset < length;) { ssize_t written = write(fd, contents + offset, length - offset); if (written < 0) { int saved_errno = errno; close(fd); unlink(path_template); errno = saved_errno; return -1; } offset += (size_t)written; } if (fchmod(fd, 0700) != 0 || close(fd) != 0) { int saved_errno = errno; unlink(path_template); errno = saved_errno; return -1; } return 0;} static int child_result(const char *name, int ok) { printf("%s: %s\n", name, ok ? "ok" : "FAIL"); return ok ? 0 : 1;} int main(int argc, char **argv) { if (argc >= 2 && strcmp(argv[1], "--execle-child") == 0) { int ok = argc == 3 && strcmp(argv[0], "execle-custom-argv0") == 0 && argv[2][0] == '\0' && getenv("EXECLE_VALUE") && strcmp(getenv("EXECLE_VALUE"), "ok") == 0; return child_result("execle", ok); } if (argc >= 2 && strcmp(argv[1], "--execvpe-child") == 0) { int ok = argc == 3 && strcmp(argv[0], "execvpe-custom-argv0") == 0 && argv[2][0] == '\0' && getenv("EXECVPE_VALUE") && strcmp(getenv("EXECVPE_VALUE"), "ok") == 0 && getenv("PATH") && strcmp(getenv("PATH"), "/definitely/not/searchable") == 0; return child_result("execvpe", ok); } if (argc >= 2 && strcmp(argv[1], "--fexecve-child") == 0) { int executable_fd = argc >= 3 ? atoi(argv[2]) : -1; errno = 0; int fd_closed = executable_fd >= 0 && fcntl(executable_fd, F_GETFD) == -1 && errno == EBADF; int ok = argc == 4 && strcmp(argv[0], "fexecve-custom-argv0") == 0 && argv[3][0] == '\0' && getenv("FEXECVE_VALUE") && strcmp(getenv("FEXECVE_VALUE"), "ok") == 0 && fd_closed; return child_result("fexecve_unlinked_cloexec", ok); } if (argc != 2) { fprintf(stderr, "usage: %s execle|execvpe|execve-shebang|shell-fallback|fexecve|" "fexecve-script|fexecve-script-cloexec\n", argv[0]); return 2; } char self_path[PATH_MAX]; if (find_self(argv[0], self_path, sizeof(self_path)) != 0) { perror("find self"); return 1; } if (strcmp(argv[1], "execle") == 0) { char *child_env[] = {"EXECLE_VALUE=ok", NULL}; execle(self_path, "execle-custom-argv0", "--execle-child", "", NULL, child_env); perror("execle"); return 1; } if (strcmp(argv[1], "execvpe") == 0) { char search_dir[PATH_MAX]; if (strlen(self_path) + 1 > sizeof(search_dir)) { errno = ENAMETOOLONG; perror("execvpe path"); return 1; } memcpy(search_dir, self_path, strlen(self_path) + 1); char *slash = strrchr(search_dir, '/'); if (slash) *slash = '\0'; else memcpy(search_dir, ".", 2); if (setenv("PATH", search_dir, 1) != 0) { perror("setenv PATH"); return 1; } char *child_argv[] = { "execvpe-custom-argv0", "--execvpe-child", "", NULL, }; char *child_env[] = { "EXECVPE_VALUE=ok", "PATH=/definitely/not/searchable", NULL, }; const char *basename = strrchr(self_path, '/'); execvpe(basename ? basename + 1 : self_path, child_argv, child_env); perror("execvpe"); return 1; } if (strcmp(argv[1], "execve-shebang") == 0) { char script_path[] = "/tmp/agentos-exec-shebang-XXXXXX"; const char contents[] = "#!/bin/sh\n" "case \"$0\" in /tmp/agentos-exec-shebang-*) ;; *) exit 8 ;; esac\n" "rm -f \"$0\"\n" "test \"$1\" = shebang-argument || exit 9\n" "printf 'execve_shebang: ok\\n'\n"; if (create_script(script_path, contents) != 0) { perror("create shebang script"); return 1; } char *child_argv[] = {"ignored-custom-script-argv0", "shebang-argument", NULL}; extern char **environ; execve(script_path, child_argv, environ); unlink(script_path); perror("execve shebang"); return 1; } if (strcmp(argv[1], "shell-fallback") == 0) { char script_path[] = "/tmp/agentos-exec-script-XXXXXX"; int script = mkstemp(script_path); const char contents[] = "rm -f \"$0\"\n" "case \"$0\" in /tmp/agentos-exec-script-*) ;; *) exit 8 ;; esac\n" "test \"$1\" = shell-argument || exit 9\n" "printf 'shell_fallback: ok\\n'\n"; if (script < 0 || write(script, contents, sizeof(contents) - 1) != (ssize_t)(sizeof(contents) - 1) || fchmod(script, 0700) != 0 || close(script) != 0) { if (script >= 0) close(script); unlink(script_path); perror("create shell fallback script"); return 1; } char search_path[PATH_MAX * 2]; const char *original_path = getenv("PATH"); int path_length = snprintf(search_path, sizeof(search_path), "/tmp:%s", original_path ? original_path : "/bin:/usr/bin"); if (path_length < 0 || (size_t)path_length >= sizeof(search_path)) { unlink(script_path); errno = ENAMETOOLONG; perror("shell PATH"); return 1; } char *basename = strrchr(script_path, '/'); if (setenv("PATH", search_path, 1) != 0) { unlink(script_path); perror("setenv shell PATH"); return 1; } if (!basename) { unlink(script_path); errno = EINVAL; perror("shell script path"); return 1; } char *child_argv[] = {basename + 1, "shell-argument", NULL}; execvp(basename + 1, child_argv); unlink(script_path); perror("execvp shell fallback"); return 1; } if (strcmp(argv[1], "fexecve") == 0) { int executable_fd; if (copy_to_unlinked_fd(self_path, &executable_fd) != 0) { perror("prepare fexecve image"); return 1; } char fd_arg[32]; snprintf(fd_arg, sizeof(fd_arg), "%d", executable_fd); char *child_argv[] = { "fexecve-custom-argv0", "--fexecve-child", fd_arg, "", NULL, }; char *child_env[] = {"FEXECVE_VALUE=ok", NULL}; fexecve(executable_fd, child_argv, child_env); perror("fexecve"); close(executable_fd); return 1; } if (strcmp(argv[1], "fexecve-script") == 0) { char script_path[] = "/tmp/agentos-fexec-script-XXXXXX"; const char contents[] = "#!/bin/sh\n" "case \"$0\" in /dev/fd/*|/proc/self/fd/*) ;; *) exit 8 ;; esac\n" "test \"$1\" = fexecve-script-argument || exit 9\n" "printf 'fexecve_script_unlinked: ok\\n'\n"; if (create_script(script_path, contents) != 0) { perror("create fexecve script"); return 1; } int script_fd = open(script_path, O_RDONLY); if (script_fd < 0 || unlink(script_path) != 0) { if (script_fd >= 0) close(script_fd); unlink(script_path); perror("prepare unlinked fexecve script"); return 1; } char *child_argv[] = { "ignored-fexecve-script-argv0", "fexecve-script-argument", NULL, }; extern char **environ; fexecve(script_fd, child_argv, environ); perror("fexecve unlinked script"); close(script_fd); return 1; } if (strcmp(argv[1], "fexecve-script-cloexec") == 0) { char script_path[] = "/tmp/agentos-fexec-cloexec-XXXXXX"; const char contents[] = "#!/bin/sh\nprintf 'unexpected script execution\\n'\n"; if (create_script(script_path, contents) != 0) { perror("create CLOEXEC fexecve script"); return 1; } int script_fd = open(script_path, O_RDONLY); char renamed_path[PATH_MAX] = {0}; int renamed_length = snprintf(renamed_path, sizeof(renamed_path), "%s.renamed", script_path); int prepare_errno = 0; if (script_fd < 0) prepare_errno = errno; else if (renamed_length < 0 || (size_t)renamed_length >= sizeof(renamed_path)) { prepare_errno = ENAMETOOLONG; } else if (rename(script_path, renamed_path) != 0) { prepare_errno = errno; } else if (fcntl(script_fd, F_SETFD, FD_CLOEXEC) != 0) { prepare_errno = errno; } if (prepare_errno != 0) { if (script_fd >= 0) close(script_fd); unlink(script_path); if (renamed_path[0] != '\0') unlink(renamed_path); errno = prepare_errno; perror("prepare CLOEXEC fexecve script"); return 1; } char *child_argv[] = {"ignored-fexecve-cloexec-argv0", NULL}; extern char **environ; errno = 0; int result = fexecve(script_fd, child_argv, environ); int exec_errno = errno; close(script_fd); unlink(renamed_path); int ok = result == -1 && exec_errno == ENOENT; return child_result("fexecve_script_cloexec_enoent", ok); } fprintf(stderr, "unknown exec variant: %s\n", argv[1]); return 2;}
#define _GNU_SOURCE
/* exec_variants.c -- Linux parity for the less-common exec entry points. */
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
static int find_self(const char *argv0, char *out, size_t out_len) {
if (strchr(argv0, '/')) {
if (strlen(argv0) + 1 > out_len) {
errno = ENAMETOOLONG;
return -1;
}
memcpy(out, argv0, strlen(argv0) + 1);
return 0;
}
const char *path = getenv("PATH");
if (!path) path = "/bin:/usr/bin";
for (const char *segment = path;;) {
const char *colon = strchr(segment, ':');
size_t dir_len = colon ? (size_t)(colon - segment) : strlen(segment);
int written = dir_len
? snprintf(out, out_len, "%.*s/%s", (int)dir_len, segment, argv0)
: snprintf(out, out_len, "./%s", argv0);
if (written >= 0 && (size_t)written < out_len && access(out, R_OK) == 0)
return 0;
if (!colon) break;
segment = colon + 1;
}
errno = ENOENT;
return -1;
}
static int copy_to_unlinked_fd(const char *source_path, int *out_fd) {
int source = open(source_path, O_RDONLY);
if (source < 0) return -1;
char copy_path[] = "/tmp/agentos-fexecve-XXXXXX";
int copy = mkstemp(copy_path);
if (copy < 0) {
close(source);
return -1;
}
char buffer[8192];
for (;;) {
ssize_t length = read(source, buffer, sizeof(buffer));
if (length < 0) goto fail;
if (length == 0) break;
for (ssize_t offset = 0; offset < length;) {
ssize_t written = write(copy, buffer + offset, (size_t)(length - offset));
if (written < 0) goto fail;
offset += written;
}
}
if (close(source) != 0) {
source = -1;
goto fail;
}
source = -1;
if (fchmod(copy, 0700) != 0) {
goto fail;
}
if (close(copy) != 0) {
copy = -1;
goto fail;
}
copy = open(copy_path, O_RDONLY);
if (copy < 0) goto fail;
if (unlink(copy_path) != 0) goto fail;
if (fcntl(copy, F_SETFD, FD_CLOEXEC) != 0)
goto fail;
*out_fd = copy;
return 0;
fail: {
int saved_errno = errno;
if (source >= 0) close(source);
if (copy >= 0) close(copy);
unlink(copy_path);
errno = saved_errno;
return -1;
}
}
static int create_script(char *path_template, const char *contents) {
int fd = mkstemp(path_template);
if (fd < 0) return -1;
size_t length = strlen(contents);
for (size_t offset = 0; offset < length;) {
ssize_t written = write(fd, contents + offset, length - offset);
if (written < 0) {
int saved_errno = errno;
close(fd);
unlink(path_template);
errno = saved_errno;
return -1;
}
offset += (size_t)written;
}
if (fchmod(fd, 0700) != 0 || close(fd) != 0) {
int saved_errno = errno;
unlink(path_template);
errno = saved_errno;
return -1;
}
return 0;
}
static int child_result(const char *name, int ok) {
printf("%s: %s\n", name, ok ? "ok" : "FAIL");
return ok ? 0 : 1;
}
int main(int argc, char **argv) {
if (argc >= 2 && strcmp(argv[1], "--execle-child") == 0) {
int ok = argc == 3 && strcmp(argv[0], "execle-custom-argv0") == 0 &&
argv[2][0] == '\0' && getenv("EXECLE_VALUE") &&
strcmp(getenv("EXECLE_VALUE"), "ok") == 0;
return child_result("execle", ok);
}
if (argc >= 2 && strcmp(argv[1], "--execvpe-child") == 0) {
int ok = argc == 3 && strcmp(argv[0], "execvpe-custom-argv0") == 0 &&
argv[2][0] == '\0' && getenv("EXECVPE_VALUE") &&
strcmp(getenv("EXECVPE_VALUE"), "ok") == 0 && getenv("PATH") &&
strcmp(getenv("PATH"), "/definitely/not/searchable") == 0;
return child_result("execvpe", ok);
}
if (argc >= 2 && strcmp(argv[1], "--fexecve-child") == 0) {
int executable_fd = argc >= 3 ? atoi(argv[2]) : -1;
errno = 0;
int fd_closed = executable_fd >= 0 && fcntl(executable_fd, F_GETFD) == -1 &&
errno == EBADF;
int ok = argc == 4 && strcmp(argv[0], "fexecve-custom-argv0") == 0 &&
argv[3][0] == '\0' && getenv("FEXECVE_VALUE") &&
strcmp(getenv("FEXECVE_VALUE"), "ok") == 0 && fd_closed;
return child_result("fexecve_unlinked_cloexec", ok);
}
if (argc != 2) {
fprintf(stderr,
"usage: %s execle|execvpe|execve-shebang|shell-fallback|fexecve|"
"fexecve-script|fexecve-script-cloexec\n",
argv[0]);
return 2;
}
char self_path[PATH_MAX];
if (find_self(argv[0], self_path, sizeof(self_path)) != 0) {
perror("find self");
return 1;
}
if (strcmp(argv[1], "execle") == 0) {
char *child_env[] = {"EXECLE_VALUE=ok", NULL};
execle(self_path, "execle-custom-argv0", "--execle-child", "", NULL,
child_env);
perror("execle");
return 1;
}
if (strcmp(argv[1], "execvpe") == 0) {
char search_dir[PATH_MAX];
if (strlen(self_path) + 1 > sizeof(search_dir)) {
errno = ENAMETOOLONG;
perror("execvpe path");
return 1;
}
memcpy(search_dir, self_path, strlen(self_path) + 1);
char *slash = strrchr(search_dir, '/');
if (slash) *slash = '\0';
else memcpy(search_dir, ".", 2);
if (setenv("PATH", search_dir, 1) != 0) {
perror("setenv PATH");
return 1;
}
char *child_argv[] = {
"execvpe-custom-argv0", "--execvpe-child", "", NULL,
};
char *child_env[] = {
"EXECVPE_VALUE=ok", "PATH=/definitely/not/searchable", NULL,
};
const char *basename = strrchr(self_path, '/');
execvpe(basename ? basename + 1 : self_path, child_argv, child_env);
perror("execvpe");
return 1;
}
if (strcmp(argv[1], "execve-shebang") == 0) {
char script_path[] = "/tmp/agentos-exec-shebang-XXXXXX";
const char contents[] =
"#!/bin/sh\n"
"case \"$0\" in /tmp/agentos-exec-shebang-*) ;; *) exit 8 ;; esac\n"
"rm -f \"$0\"\n"
"test \"$1\" = shebang-argument || exit 9\n"
"printf 'execve_shebang: ok\\n'\n";
if (create_script(script_path, contents) != 0) {
perror("create shebang script");
return 1;
}
char *child_argv[] = {"ignored-custom-script-argv0", "shebang-argument", NULL};
extern char **environ;
execve(script_path, child_argv, environ);
unlink(script_path);
perror("execve shebang");
return 1;
}
if (strcmp(argv[1], "shell-fallback") == 0) {
char script_path[] = "/tmp/agentos-exec-script-XXXXXX";
int script = mkstemp(script_path);
const char contents[] =
"rm -f \"$0\"\n"
"case \"$0\" in /tmp/agentos-exec-script-*) ;; *) exit 8 ;; esac\n"
"test \"$1\" = shell-argument || exit 9\n"
"printf 'shell_fallback: ok\\n'\n";
if (script < 0 || write(script, contents, sizeof(contents) - 1) !=
(ssize_t)(sizeof(contents) - 1) ||
fchmod(script, 0700) != 0 || close(script) != 0) {
if (script >= 0) close(script);
unlink(script_path);
perror("create shell fallback script");
return 1;
}
char search_path[PATH_MAX * 2];
const char *original_path = getenv("PATH");
int path_length = snprintf(search_path, sizeof(search_path), "/tmp:%s",
original_path ? original_path : "/bin:/usr/bin");
if (path_length < 0 || (size_t)path_length >= sizeof(search_path)) {
unlink(script_path);
errno = ENAMETOOLONG;
perror("shell PATH");
return 1;
}
char *basename = strrchr(script_path, '/');
if (setenv("PATH", search_path, 1) != 0) {
unlink(script_path);
perror("setenv shell PATH");
return 1;
}
if (!basename) {
unlink(script_path);
errno = EINVAL;
perror("shell script path");
return 1;
}
char *child_argv[] = {basename + 1, "shell-argument", NULL};
execvp(basename + 1, child_argv);
unlink(script_path);
perror("execvp shell fallback");
return 1;
}
if (strcmp(argv[1], "fexecve") == 0) {
int executable_fd;
if (copy_to_unlinked_fd(self_path, &executable_fd) != 0) {
perror("prepare fexecve image");
return 1;
}
char fd_arg[32];
snprintf(fd_arg, sizeof(fd_arg), "%d", executable_fd);
char *child_argv[] = {
"fexecve-custom-argv0", "--fexecve-child", fd_arg, "", NULL,
};
char *child_env[] = {"FEXECVE_VALUE=ok", NULL};
fexecve(executable_fd, child_argv, child_env);
perror("fexecve");
close(executable_fd);
return 1;
}
if (strcmp(argv[1], "fexecve-script") == 0) {
char script_path[] = "/tmp/agentos-fexec-script-XXXXXX";
const char contents[] =
"#!/bin/sh\n"
"case \"$0\" in /dev/fd/*|/proc/self/fd/*) ;; *) exit 8 ;; esac\n"
"test \"$1\" = fexecve-script-argument || exit 9\n"
"printf 'fexecve_script_unlinked: ok\\n'\n";
if (create_script(script_path, contents) != 0) {
perror("create fexecve script");
return 1;
}
int script_fd = open(script_path, O_RDONLY);
if (script_fd < 0 || unlink(script_path) != 0) {
if (script_fd >= 0) close(script_fd);
unlink(script_path);
perror("prepare unlinked fexecve script");
return 1;
}
char *child_argv[] = {
"ignored-fexecve-script-argv0", "fexecve-script-argument", NULL,
};
extern char **environ;
fexecve(script_fd, child_argv, environ);
perror("fexecve unlinked script");
close(script_fd);
return 1;
}
if (strcmp(argv[1], "fexecve-script-cloexec") == 0) {
char script_path[] = "/tmp/agentos-fexec-cloexec-XXXXXX";
const char contents[] = "#!/bin/sh\nprintf 'unexpected script execution\\n'\n";
if (create_script(script_path, contents) != 0) {
perror("create CLOEXEC fexecve script");
return 1;
}
int script_fd = open(script_path, O_RDONLY);
char renamed_path[PATH_MAX] = {0};
int renamed_length = snprintf(renamed_path, sizeof(renamed_path), "%s.renamed",
script_path);
int prepare_errno = 0;
if (script_fd < 0) prepare_errno = errno;
else if (renamed_length < 0 ||
(size_t)renamed_length >= sizeof(renamed_path)) {
prepare_errno = ENAMETOOLONG;
} else if (rename(script_path, renamed_path) != 0) {
prepare_errno = errno;
} else if (fcntl(script_fd, F_SETFD, FD_CLOEXEC) != 0) {
prepare_errno = errno;
}
if (prepare_errno != 0) {
if (script_fd >= 0) close(script_fd);
unlink(script_path);
if (renamed_path[0] != '\0') unlink(renamed_path);
errno = prepare_errno;
perror("prepare CLOEXEC fexecve script");
return 1;
}
char *child_argv[] = {"ignored-fexecve-cloexec-argv0", NULL};
extern char **environ;
errno = 0;
int result = fexecve(script_fd, child_argv, environ);
int exec_errno = errno;
close(script_fd);
unlink(renamed_path);
int ok = result == -1 && exec_errno == ENOENT;
return child_result("fexecve_script_cloexec_enoent", ok);
}
fprintf(stderr, "unknown exec variant: %s\n", argv[1]);
return 2;
}