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-rw-r--r--src/shared/exec-util.c605
1 files changed, 605 insertions, 0 deletions
diff --git a/src/shared/exec-util.c b/src/shared/exec-util.c
new file mode 100644
index 0000000..c27f3a5
--- /dev/null
+++ b/src/shared/exec-util.c
@@ -0,0 +1,605 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <dirent.h>
+#include <errno.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#include "alloc-util.h"
+#include "conf-files.h"
+#include "env-file.h"
+#include "env-util.h"
+#include "errno-util.h"
+#include "escape.h"
+#include "exec-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "hashmap.h"
+#include "macro.h"
+#include "missing_syscall.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "serialize.h"
+#include "set.h"
+#include "signal-util.h"
+#include "stat-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "strv.h"
+#include "terminal-util.h"
+#include "tmpfile-util.h"
+
+#define EXIT_SKIP_REMAINING 77
+
+/* Put this test here for a lack of better place */
+assert_cc(EAGAIN == EWOULDBLOCK);
+
+static int do_spawn(const char *path, char *argv[], int stdout_fd, pid_t *pid, bool set_systemd_exec_pid) {
+ pid_t _pid;
+ int r;
+
+ if (null_or_empty_path(path) > 0) {
+ log_debug("%s is empty (a mask).", path);
+ return 0;
+ }
+
+ r = safe_fork("(direxec)", FORK_DEATHSIG_SIGTERM|FORK_LOG|FORK_RLIMIT_NOFILE_SAFE, &_pid);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ char *_argv[2];
+
+ if (stdout_fd >= 0) {
+ r = rearrange_stdio(STDIN_FILENO, TAKE_FD(stdout_fd), STDERR_FILENO);
+ if (r < 0)
+ _exit(EXIT_FAILURE);
+ }
+
+ if (set_systemd_exec_pid) {
+ r = setenv_systemd_exec_pid(false);
+ if (r < 0)
+ log_warning_errno(r, "Failed to set $SYSTEMD_EXEC_PID, ignoring: %m");
+ }
+
+ if (!argv) {
+ _argv[0] = (char*) path;
+ _argv[1] = NULL;
+ argv = _argv;
+ } else
+ argv[0] = (char*) path;
+
+ execv(path, argv);
+ log_error_errno(errno, "Failed to execute %s: %m", path);
+ _exit(EXIT_FAILURE);
+ }
+
+ *pid = _pid;
+ return 1;
+}
+
+static int do_execute(
+ char* const* paths,
+ const char *root,
+ usec_t timeout,
+ gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
+ void* const callback_args[_STDOUT_CONSUME_MAX],
+ int output_fd,
+ char *argv[],
+ char *envp[],
+ ExecDirFlags flags) {
+
+ _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
+ bool parallel_execution;
+ int r;
+
+ /* We fork this all off from a child process so that we can somewhat cleanly make
+ * use of SIGALRM to set a time limit.
+ *
+ * We attempt to perform parallel execution if configured by the user, however
+ * if `callbacks` is nonnull, execution must be serial.
+ */
+ parallel_execution = FLAGS_SET(flags, EXEC_DIR_PARALLEL) && !callbacks;
+
+ if (parallel_execution) {
+ pids = hashmap_new(NULL);
+ if (!pids)
+ return log_oom();
+ }
+
+ /* Abort execution of this process after the timeout. We simply rely on SIGALRM as
+ * default action terminating the process, and turn on alarm(). */
+
+ if (timeout != USEC_INFINITY)
+ alarm(DIV_ROUND_UP(timeout, USEC_PER_SEC));
+
+ STRV_FOREACH(e, envp)
+ if (putenv(*e) != 0)
+ return log_error_errno(errno, "Failed to set environment variable: %m");
+
+ STRV_FOREACH(path, paths) {
+ _cleanup_free_ char *t = NULL;
+ _cleanup_close_ int fd = -EBADF;
+ pid_t pid;
+
+ t = path_join(root, *path);
+ if (!t)
+ return log_oom();
+
+ if (callbacks) {
+ _cleanup_free_ char *bn = NULL;
+
+ r = path_extract_filename(*path, &bn);
+ if (r < 0)
+ return log_error_errno(r, "Failed to extract filename from path '%s': %m", *path);
+
+ fd = open_serialization_fd(bn);
+ if (fd < 0)
+ return log_error_errno(fd, "Failed to open serialization file: %m");
+ }
+
+ if (DEBUG_LOGGING) {
+ _cleanup_free_ char *args = NULL;
+ if (argv)
+ args = quote_command_line(strv_skip(argv, 1), SHELL_ESCAPE_EMPTY);
+
+ log_debug("About to execute %s%s%s", t, argv ? " " : "", argv ? strnull(args) : "");
+ }
+
+ r = do_spawn(t, argv, fd, &pid, FLAGS_SET(flags, EXEC_DIR_SET_SYSTEMD_EXEC_PID));
+ if (r <= 0)
+ continue;
+
+ if (parallel_execution) {
+ r = hashmap_put(pids, PID_TO_PTR(pid), t);
+ if (r < 0)
+ return log_oom();
+ t = NULL;
+ } else {
+ bool skip_remaining = false;
+
+ r = wait_for_terminate_and_check(t, pid, WAIT_LOG_ABNORMAL);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ if (FLAGS_SET(flags, EXEC_DIR_SKIP_REMAINING) && r == EXIT_SKIP_REMAINING) {
+ log_info("%s succeeded with exit status %i, not executing remaining executables.", *path, r);
+ skip_remaining = true;
+ } else if (FLAGS_SET(flags, EXEC_DIR_IGNORE_ERRORS))
+ log_warning("%s failed with exit status %i, ignoring.", *path, r);
+ else {
+ log_error("%s failed with exit status %i.", *path, r);
+ return r;
+ }
+ }
+
+ if (callbacks) {
+ if (lseek(fd, 0, SEEK_SET) < 0)
+ return log_error_errno(errno, "Failed to seek on serialization fd: %m");
+
+ r = callbacks[STDOUT_GENERATE](TAKE_FD(fd), callback_args[STDOUT_GENERATE]);
+ if (r < 0)
+ return log_error_errno(r, "Failed to process output from %s: %m", *path);
+ }
+
+ if (skip_remaining)
+ break;
+ }
+ }
+
+ if (callbacks) {
+ r = callbacks[STDOUT_COLLECT](output_fd, callback_args[STDOUT_COLLECT]);
+ if (r < 0)
+ return log_error_errno(r, "Callback two failed: %m");
+ }
+
+ while (!hashmap_isempty(pids)) {
+ _cleanup_free_ char *t = NULL;
+ pid_t pid;
+
+ pid = PTR_TO_PID(hashmap_first_key(pids));
+ assert(pid > 0);
+
+ t = hashmap_remove(pids, PID_TO_PTR(pid));
+ assert(t);
+
+ r = wait_for_terminate_and_check(t, pid, WAIT_LOG);
+ if (r < 0)
+ return r;
+ if (!FLAGS_SET(flags, EXEC_DIR_IGNORE_ERRORS) && r > 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int execute_strv(
+ const char *name,
+ char* const* paths,
+ const char *root,
+ usec_t timeout,
+ gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
+ void* const callback_args[_STDOUT_CONSUME_MAX],
+ char *argv[],
+ char *envp[],
+ ExecDirFlags flags) {
+
+ _cleanup_close_ int fd = -EBADF;
+ pid_t executor_pid;
+ int r;
+
+ assert(!FLAGS_SET(flags, EXEC_DIR_PARALLEL | EXEC_DIR_SKIP_REMAINING));
+
+ if (strv_isempty(paths))
+ return 0;
+
+ if (callbacks) {
+ assert(name);
+ assert(callback_args);
+ assert(callbacks[STDOUT_GENERATE]);
+ assert(callbacks[STDOUT_COLLECT]);
+ assert(callbacks[STDOUT_CONSUME]);
+
+ fd = open_serialization_fd(name);
+ if (fd < 0)
+ return log_error_errno(fd, "Failed to open serialization file: %m");
+ }
+
+ /* Executes all binaries in the directories serially or in parallel and waits for
+ * them to finish. Optionally a timeout is applied. If a file with the same name
+ * exists in more than one directory, the earliest one wins. */
+
+ r = safe_fork("(sd-exec-strv)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_LOG, &executor_pid);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ r = do_execute(paths, root, timeout, callbacks, callback_args, fd, argv, envp, flags);
+ _exit(r < 0 ? EXIT_FAILURE : r);
+ }
+
+ r = wait_for_terminate_and_check("(sd-exec-strv)", executor_pid, 0);
+ if (r < 0)
+ return r;
+ if (!FLAGS_SET(flags, EXEC_DIR_IGNORE_ERRORS) && r > 0)
+ return r;
+
+ if (!callbacks)
+ return 0;
+
+ if (lseek(fd, 0, SEEK_SET) < 0)
+ return log_error_errno(errno, "Failed to rewind serialization fd: %m");
+
+ r = callbacks[STDOUT_CONSUME](TAKE_FD(fd), callback_args[STDOUT_CONSUME]);
+ if (r < 0)
+ return log_error_errno(r, "Failed to parse returned data: %m");
+ return 0;
+}
+
+int execute_directories(
+ const char* const* directories,
+ usec_t timeout,
+ gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
+ void* const callback_args[_STDOUT_CONSUME_MAX],
+ char *argv[],
+ char *envp[],
+ ExecDirFlags flags) {
+
+ _cleanup_strv_free_ char **paths = NULL;
+ _cleanup_free_ char *name = NULL;
+ int r;
+
+ assert(!strv_isempty((char**) directories));
+
+ r = conf_files_list_strv(&paths, NULL, NULL, CONF_FILES_EXECUTABLE|CONF_FILES_REGULAR|CONF_FILES_FILTER_MASKED, directories);
+ if (r < 0)
+ return log_error_errno(r, "Failed to enumerate executables: %m");
+
+ if (strv_isempty(paths)) {
+ log_debug("No executables found.");
+ return 0;
+ }
+
+ if (callbacks) {
+ r = path_extract_filename(directories[0], &name);
+ if (r < 0)
+ return log_error_errno(r, "Failed to extract file name from '%s': %m", directories[0]);
+ }
+
+ return execute_strv(name, paths, NULL, timeout, callbacks, callback_args, argv, envp, flags);
+}
+
+static int gather_environment_generate(int fd, void *arg) {
+ char ***env = ASSERT_PTR(arg);
+ _cleanup_fclose_ FILE *f = NULL;
+ _cleanup_strv_free_ char **new = NULL;
+ int r;
+
+ /* Read a series of VAR=value assignments from fd, use them to update the list of
+ * variables in env. Also update the exported environment.
+ *
+ * fd is always consumed, even on error.
+ */
+
+ f = fdopen(fd, "r");
+ if (!f) {
+ safe_close(fd);
+ return -errno;
+ }
+
+ r = load_env_file_pairs(f, NULL, &new);
+ if (r < 0)
+ return r;
+
+ STRV_FOREACH_PAIR(x, y, new) {
+ if (!env_name_is_valid(*x)) {
+ log_warning("Invalid variable assignment \"%s=...\", ignoring.", *x);
+ continue;
+ }
+
+ r = strv_env_assign(env, *x, *y);
+ if (r < 0)
+ return r;
+
+ if (setenv(*x, *y, true) < 0)
+ return -errno;
+ }
+
+ return 0;
+}
+
+static int gather_environment_collect(int fd, void *arg) {
+ _cleanup_fclose_ FILE *f = NULL;
+ char ***env = ASSERT_PTR(arg);
+ int r;
+
+ /* Write out a series of env=cescape(VAR=value) assignments to fd. */
+
+ f = fdopen(fd, "w");
+ if (!f) {
+ safe_close(fd);
+ return -errno;
+ }
+
+ r = serialize_strv(f, "env", *env);
+ if (r < 0)
+ return r;
+
+ r = fflush_and_check(f);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int gather_environment_consume(int fd, void *arg) {
+ _cleanup_fclose_ FILE *f = NULL;
+ char ***env = ASSERT_PTR(arg);
+ int r = 0;
+
+ /* Read a series of env=cescape(VAR=value) assignments from fd into env. */
+
+ f = fdopen(fd, "r");
+ if (!f) {
+ safe_close(fd);
+ return -errno;
+ }
+
+ for (;;) {
+ _cleanup_free_ char *line = NULL;
+ const char *v;
+ int k;
+
+ k = read_line(f, LONG_LINE_MAX, &line);
+ if (k < 0)
+ return k;
+ if (k == 0)
+ break;
+
+ v = startswith(line, "env=");
+ if (!v) {
+ log_debug("Serialization line \"%s\" unexpectedly didn't start with \"env=\".", line);
+ if (r == 0)
+ r = -EINVAL;
+
+ continue;
+ }
+
+ k = deserialize_environment(v, env);
+ if (k < 0) {
+ log_debug_errno(k, "Invalid serialization line \"%s\": %m", line);
+
+ if (r == 0)
+ r = k;
+ }
+ }
+
+ return r;
+}
+
+int exec_command_flags_from_strv(char **ex_opts, ExecCommandFlags *flags) {
+ ExecCommandFlags ex_flag, ret_flags = 0;
+
+ assert(flags);
+
+ STRV_FOREACH(opt, ex_opts) {
+ ex_flag = exec_command_flags_from_string(*opt);
+ if (ex_flag < 0)
+ return ex_flag;
+ ret_flags |= ex_flag;
+ }
+
+ *flags = ret_flags;
+
+ return 0;
+}
+
+int exec_command_flags_to_strv(ExecCommandFlags flags, char ***ex_opts) {
+ _cleanup_strv_free_ char **ret_opts = NULL;
+ ExecCommandFlags it = flags;
+ const char *str;
+ int r;
+
+ assert(ex_opts);
+
+ if (flags < 0)
+ return flags;
+
+ for (unsigned i = 0; it != 0; it &= ~(1 << i), i++)
+ if (FLAGS_SET(flags, (1 << i))) {
+ str = exec_command_flags_to_string(1 << i);
+ if (!str)
+ return -EINVAL;
+
+ r = strv_extend(&ret_opts, str);
+ if (r < 0)
+ return r;
+ }
+
+ *ex_opts = TAKE_PTR(ret_opts);
+
+ return 0;
+}
+
+const gather_stdout_callback_t gather_environment[] = {
+ gather_environment_generate,
+ gather_environment_collect,
+ gather_environment_consume,
+};
+
+static const char* const exec_command_strings[] = {
+ "ignore-failure", /* EXEC_COMMAND_IGNORE_FAILURE */
+ "privileged", /* EXEC_COMMAND_FULLY_PRIVILEGED */
+ "no-setuid", /* EXEC_COMMAND_NO_SETUID */
+ "ambient", /* EXEC_COMMAND_AMBIENT_MAGIC */
+ "no-env-expand", /* EXEC_COMMAND_NO_ENV_EXPAND */
+};
+
+const char* exec_command_flags_to_string(ExecCommandFlags i) {
+ for (size_t idx = 0; idx < ELEMENTSOF(exec_command_strings); idx++)
+ if (i == (1 << idx))
+ return exec_command_strings[idx];
+
+ return NULL;
+}
+
+ExecCommandFlags exec_command_flags_from_string(const char *s) {
+ ssize_t idx;
+
+ idx = string_table_lookup(exec_command_strings, ELEMENTSOF(exec_command_strings), s);
+
+ if (idx < 0)
+ return _EXEC_COMMAND_FLAGS_INVALID;
+ else
+ return 1 << idx;
+}
+
+int fexecve_or_execve(int executable_fd, const char *executable, char *const argv[], char *const envp[]) {
+ /* Refuse invalid fds, regardless if fexecve() use is enabled or not */
+ if (executable_fd < 0)
+ return -EBADF;
+
+ /* Block any attempts on exploiting Linux' liberal argv[] handling, i.e. CVE-2021-4034 and suchlike */
+ if (isempty(executable) || strv_isempty(argv))
+ return -EINVAL;
+
+#if ENABLE_FEXECVE
+
+ execveat(executable_fd, "", argv, envp, AT_EMPTY_PATH);
+
+ if (IN_SET(errno, ENOSYS, ENOENT) || ERRNO_IS_PRIVILEGE(errno))
+ /* Old kernel or a script or an overzealous seccomp filter? Let's fall back to execve().
+ *
+ * fexecve(3): "If fd refers to a script (i.e., it is an executable text file that names a
+ * script interpreter with a first line that begins with the characters #!) and the
+ * close-on-exec flag has been set for fd, then fexecve() fails with the error ENOENT. This
+ * error occurs because, by the time the script interpreter is executed, fd has already been
+ * closed because of the close-on-exec flag. Thus, the close-on-exec flag can't be set on fd
+ * if it refers to a script."
+ *
+ * Unfortunately, if we unset close-on-exec, the script will be executed just fine, but (at
+ * least in case of bash) the script name, $0, will be shown as /dev/fd/nnn, which breaks
+ * scripts which make use of $0. Thus, let's fall back to execve() in this case.
+ */
+#endif
+ execve(executable, argv, envp);
+ return -errno;
+}
+
+int fork_agent(const char *name, const int except[], size_t n_except, pid_t *ret_pid, const char *path, ...) {
+ bool stdout_is_tty, stderr_is_tty;
+ size_t n, i;
+ va_list ap;
+ char **l;
+ int r;
+
+ assert(path);
+
+ /* Spawns a temporary TTY agent, making sure it goes away when we go away */
+
+ r = safe_fork_full(name,
+ NULL,
+ except,
+ n_except,
+ FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_CLOSE_ALL_FDS|FORK_REOPEN_LOG|FORK_RLIMIT_NOFILE_SAFE,
+ ret_pid);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ return 0;
+
+ /* In the child: */
+
+ stdout_is_tty = isatty(STDOUT_FILENO);
+ stderr_is_tty = isatty(STDERR_FILENO);
+
+ if (!stdout_is_tty || !stderr_is_tty) {
+ int fd;
+
+ /* Detach from stdout/stderr and reopen /dev/tty for them. This is important to ensure that
+ * when systemctl is started via popen() or a similar call that expects to read EOF we
+ * actually do generate EOF and not delay this indefinitely by keeping an unused copy of
+ * stdin around. */
+ fd = open("/dev/tty", O_WRONLY);
+ if (fd < 0) {
+ if (errno != ENXIO) {
+ log_error_errno(errno, "Failed to open /dev/tty: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ /* If we get ENXIO here we have no controlling TTY even though stdout/stderr are
+ * connected to a TTY. That's a weird setup, but let's handle it gracefully: let's
+ * skip the forking of the agents, given the TTY setup is not in order. */
+ } else {
+ if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) {
+ log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) {
+ log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ fd = safe_close_above_stdio(fd);
+ }
+ }
+
+ /* Count arguments */
+ va_start(ap, path);
+ for (n = 0; va_arg(ap, char*); n++)
+ ;
+ va_end(ap);
+
+ /* Allocate strv */
+ l = newa(char*, n + 1);
+
+ /* Fill in arguments */
+ va_start(ap, path);
+ for (i = 0; i <= n; i++)
+ l[i] = va_arg(ap, char*);
+ va_end(ap);
+
+ execv(path, l);
+ _exit(EXIT_FAILURE);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-24 19:11:02 +0000