diff options
Diffstat (limited to 'src/core/exec-invoke.c')
| -rw-r--r-- | src/core/exec-invoke.c | 5235 |
1 files changed, 5235 insertions, 0 deletions
diff --git a/src/core/exec-invoke.c b/src/core/exec-invoke.c new file mode 100644 index 0000000..28d6142 --- /dev/null +++ b/src/core/exec-invoke.c @@ -0,0 +1,5235 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <sys/eventfd.h> +#include <sys/ioctl.h> +#include <sys/mount.h> +#include <sys/prctl.h> + +#if HAVE_PAM +#include <security/pam_appl.h> +#include <security/pam_misc.h> +#endif + +#if HAVE_APPARMOR +#include <sys/apparmor.h> +#endif + +#include "sd-messages.h" + +#if HAVE_APPARMOR +#include "apparmor-util.h" +#endif +#include "argv-util.h" +#include "barrier.h" +#include "bpf-dlopen.h" +#include "bpf-lsm.h" +#include "btrfs-util.h" +#include "capability-util.h" +#include "cgroup-setup.h" +#include "chase.h" +#include "chattr-util.h" +#include "chown-recursive.h" +#include "copy.h" +#include "data-fd-util.h" +#include "env-util.h" +#include "escape.h" +#include "exec-credential.h" +#include "exec-invoke.h" +#include "execute.h" +#include "exit-status.h" +#include "fd-util.h" +#include "hexdecoct.h" +#include "io-util.h" +#include "iovec-util.h" +#include "missing_ioprio.h" +#include "missing_prctl.h" +#include "missing_securebits.h" +#include "missing_syscall.h" +#include "mkdir-label.h" +#include "proc-cmdline.h" +#include "process-util.h" +#include "psi-util.h" +#include "rlimit-util.h" +#include "seccomp-util.h" +#include "selinux-util.h" +#include "signal-util.h" +#include "smack-util.h" +#include "socket-util.h" +#include "string-table.h" +#include "strv.h" +#include "terminal-util.h" +#include "utmp-wtmp.h" + +#define IDLE_TIMEOUT_USEC (5*USEC_PER_SEC) +#define IDLE_TIMEOUT2_USEC (1*USEC_PER_SEC) + +#define SNDBUF_SIZE (8*1024*1024) + +static int shift_fds(int fds[], size_t n_fds) { + if (n_fds <= 0) + return 0; + + /* Modifies the fds array! (sorts it) */ + + assert(fds); + + for (int start = 0;;) { + int restart_from = -1; + + for (int i = start; i < (int) n_fds; i++) { + int nfd; + + /* Already at right index? */ + if (fds[i] == i+3) + continue; + + nfd = fcntl(fds[i], F_DUPFD, i + 3); + if (nfd < 0) + return -errno; + + safe_close(fds[i]); + fds[i] = nfd; + + /* Hmm, the fd we wanted isn't free? Then + * let's remember that and try again from here */ + if (nfd != i+3 && restart_from < 0) + restart_from = i; + } + + if (restart_from < 0) + break; + + start = restart_from; + } + + return 0; +} + +static int flag_fds( + const int fds[], + size_t n_socket_fds, + size_t n_fds, + bool nonblock) { + + int r; + + assert(fds || n_fds == 0); + + /* Drops/Sets O_NONBLOCK and FD_CLOEXEC from the file flags. + * O_NONBLOCK only applies to socket activation though. */ + + for (size_t i = 0; i < n_fds; i++) { + + if (i < n_socket_fds) { + r = fd_nonblock(fds[i], nonblock); + if (r < 0) + return r; + } + + /* We unconditionally drop FD_CLOEXEC from the fds, + * since after all we want to pass these fds to our + * children */ + + r = fd_cloexec(fds[i], false); + if (r < 0) + return r; + } + + return 0; +} + +static bool is_terminal_input(ExecInput i) { + return IN_SET(i, + EXEC_INPUT_TTY, + EXEC_INPUT_TTY_FORCE, + EXEC_INPUT_TTY_FAIL); +} + +static bool is_terminal_output(ExecOutput o) { + return IN_SET(o, + EXEC_OUTPUT_TTY, + EXEC_OUTPUT_KMSG_AND_CONSOLE, + EXEC_OUTPUT_JOURNAL_AND_CONSOLE); +} + +static bool is_kmsg_output(ExecOutput o) { + return IN_SET(o, + EXEC_OUTPUT_KMSG, + EXEC_OUTPUT_KMSG_AND_CONSOLE); +} + +static bool exec_context_needs_term(const ExecContext *c) { + assert(c); + + /* Return true if the execution context suggests we should set $TERM to something useful. */ + + if (is_terminal_input(c->std_input)) + return true; + + if (is_terminal_output(c->std_output)) + return true; + + if (is_terminal_output(c->std_error)) + return true; + + return !!c->tty_path; +} + +static int open_null_as(int flags, int nfd) { + int fd; + + assert(nfd >= 0); + + fd = open("/dev/null", flags|O_NOCTTY); + if (fd < 0) + return -errno; + + return move_fd(fd, nfd, false); +} + +static int connect_journal_socket( + int fd, + const char *log_namespace, + uid_t uid, + gid_t gid) { + + uid_t olduid = UID_INVALID; + gid_t oldgid = GID_INVALID; + const char *j; + int r; + + j = log_namespace ? + strjoina("/run/systemd/journal.", log_namespace, "/stdout") : + "/run/systemd/journal/stdout"; + + if (gid_is_valid(gid)) { + oldgid = getgid(); + + if (setegid(gid) < 0) + return -errno; + } + + if (uid_is_valid(uid)) { + olduid = getuid(); + + if (seteuid(uid) < 0) { + r = -errno; + goto restore_gid; + } + } + + r = connect_unix_path(fd, AT_FDCWD, j); + + /* If we fail to restore the uid or gid, things will likely fail later on. This should only happen if + an LSM interferes. */ + + if (uid_is_valid(uid)) + (void) seteuid(olduid); + + restore_gid: + if (gid_is_valid(gid)) + (void) setegid(oldgid); + + return r; +} + +static int connect_logger_as( + const ExecContext *context, + const ExecParameters *params, + ExecOutput output, + const char *ident, + int nfd, + uid_t uid, + gid_t gid) { + + _cleanup_close_ int fd = -EBADF; + int r; + + assert(context); + assert(params); + assert(output < _EXEC_OUTPUT_MAX); + assert(ident); + assert(nfd >= 0); + + fd = socket(AF_UNIX, SOCK_STREAM, 0); + if (fd < 0) + return -errno; + + r = connect_journal_socket(fd, context->log_namespace, uid, gid); + if (r < 0) + return r; + + if (shutdown(fd, SHUT_RD) < 0) + return -errno; + + (void) fd_inc_sndbuf(fd, SNDBUF_SIZE); + + if (dprintf(fd, + "%s\n" + "%s\n" + "%i\n" + "%i\n" + "%i\n" + "%i\n" + "%i\n", + context->syslog_identifier ?: ident, + params->flags & EXEC_PASS_LOG_UNIT ? params->unit_id : "", + context->syslog_priority, + !!context->syslog_level_prefix, + false, + is_kmsg_output(output), + is_terminal_output(output)) < 0) + return -errno; + + return move_fd(TAKE_FD(fd), nfd, false); +} + +static int open_terminal_as(const char *path, int flags, int nfd) { + int fd; + + assert(path); + assert(nfd >= 0); + + fd = open_terminal(path, flags | O_NOCTTY); + if (fd < 0) + return fd; + + return move_fd(fd, nfd, false); +} + +static int acquire_path(const char *path, int flags, mode_t mode) { + _cleanup_close_ int fd = -EBADF; + int r; + + assert(path); + + if (IN_SET(flags & O_ACCMODE, O_WRONLY, O_RDWR)) + flags |= O_CREAT; + + fd = open(path, flags|O_NOCTTY, mode); + if (fd >= 0) + return TAKE_FD(fd); + + if (errno != ENXIO) /* ENXIO is returned when we try to open() an AF_UNIX file system socket on Linux */ + return -errno; + + /* So, it appears the specified path could be an AF_UNIX socket. Let's see if we can connect to it. */ + + fd = socket(AF_UNIX, SOCK_STREAM, 0); + if (fd < 0) + return -errno; + + r = connect_unix_path(fd, AT_FDCWD, path); + if (IN_SET(r, -ENOTSOCK, -EINVAL)) + /* Propagate initial error if we get ENOTSOCK or EINVAL, i.e. we have indication that this + * wasn't an AF_UNIX socket after all */ + return -ENXIO; + if (r < 0) + return r; + + if ((flags & O_ACCMODE) == O_RDONLY) + r = shutdown(fd, SHUT_WR); + else if ((flags & O_ACCMODE) == O_WRONLY) + r = shutdown(fd, SHUT_RD); + else + r = 0; + if (r < 0) + return -errno; + + return TAKE_FD(fd); +} + +static int fixup_input( + const ExecContext *context, + int socket_fd, + bool apply_tty_stdin) { + + ExecInput std_input; + + assert(context); + + std_input = context->std_input; + + if (is_terminal_input(std_input) && !apply_tty_stdin) + return EXEC_INPUT_NULL; + + if (std_input == EXEC_INPUT_SOCKET && socket_fd < 0) + return EXEC_INPUT_NULL; + + if (std_input == EXEC_INPUT_DATA && context->stdin_data_size == 0) + return EXEC_INPUT_NULL; + + return std_input; +} + +static int fixup_output(ExecOutput output, int socket_fd) { + + if (output == EXEC_OUTPUT_SOCKET && socket_fd < 0) + return EXEC_OUTPUT_INHERIT; + + return output; +} + +static int setup_input( + const ExecContext *context, + const ExecParameters *params, + int socket_fd, + const int named_iofds[static 3]) { + + ExecInput i; + int r; + + assert(context); + assert(params); + assert(named_iofds); + + if (params->stdin_fd >= 0) { + if (dup2(params->stdin_fd, STDIN_FILENO) < 0) + return -errno; + + /* Try to make this the controlling tty, if it is a tty, and reset it */ + if (isatty(STDIN_FILENO)) { + (void) ioctl(STDIN_FILENO, TIOCSCTTY, context->std_input == EXEC_INPUT_TTY_FORCE); + + if (context->tty_reset) + (void) reset_terminal_fd(STDIN_FILENO, /* switch_to_text= */ true); + + (void) exec_context_apply_tty_size(context, STDIN_FILENO, /* tty_path= */ NULL); + } + + return STDIN_FILENO; + } + + i = fixup_input(context, socket_fd, params->flags & EXEC_APPLY_TTY_STDIN); + + switch (i) { + + case EXEC_INPUT_NULL: + return open_null_as(O_RDONLY, STDIN_FILENO); + + case EXEC_INPUT_TTY: + case EXEC_INPUT_TTY_FORCE: + case EXEC_INPUT_TTY_FAIL: { + _cleanup_close_ int tty_fd = -EBADF; + const char *tty_path; + + tty_path = ASSERT_PTR(exec_context_tty_path(context)); + + tty_fd = acquire_terminal(tty_path, + i == EXEC_INPUT_TTY_FAIL ? ACQUIRE_TERMINAL_TRY : + i == EXEC_INPUT_TTY_FORCE ? ACQUIRE_TERMINAL_FORCE : + ACQUIRE_TERMINAL_WAIT, + USEC_INFINITY); + if (tty_fd < 0) + return tty_fd; + + r = exec_context_apply_tty_size(context, tty_fd, tty_path); + if (r < 0) + return r; + + r = move_fd(tty_fd, STDIN_FILENO, /* cloexec= */ false); + if (r < 0) + return r; + + TAKE_FD(tty_fd); + return r; + } + + case EXEC_INPUT_SOCKET: + assert(socket_fd >= 0); + + return RET_NERRNO(dup2(socket_fd, STDIN_FILENO)); + + case EXEC_INPUT_NAMED_FD: + assert(named_iofds[STDIN_FILENO] >= 0); + + (void) fd_nonblock(named_iofds[STDIN_FILENO], false); + return RET_NERRNO(dup2(named_iofds[STDIN_FILENO], STDIN_FILENO)); + + case EXEC_INPUT_DATA: { + int fd; + + fd = acquire_data_fd(context->stdin_data, context->stdin_data_size, 0); + if (fd < 0) + return fd; + + return move_fd(fd, STDIN_FILENO, false); + } + + case EXEC_INPUT_FILE: { + bool rw; + int fd; + + assert(context->stdio_file[STDIN_FILENO]); + + rw = (context->std_output == EXEC_OUTPUT_FILE && streq_ptr(context->stdio_file[STDIN_FILENO], context->stdio_file[STDOUT_FILENO])) || + (context->std_error == EXEC_OUTPUT_FILE && streq_ptr(context->stdio_file[STDIN_FILENO], context->stdio_file[STDERR_FILENO])); + + fd = acquire_path(context->stdio_file[STDIN_FILENO], rw ? O_RDWR : O_RDONLY, 0666 & ~context->umask); + if (fd < 0) + return fd; + + return move_fd(fd, STDIN_FILENO, false); + } + + default: + assert_not_reached(); + } +} + +static bool can_inherit_stderr_from_stdout( + const ExecContext *context, + ExecOutput o, + ExecOutput e) { + + assert(context); + + /* Returns true, if given the specified STDERR and STDOUT output we can directly dup() the stdout fd to the + * stderr fd */ + + if (e == EXEC_OUTPUT_INHERIT) + return true; + if (e != o) + return false; + + if (e == EXEC_OUTPUT_NAMED_FD) + return streq_ptr(context->stdio_fdname[STDOUT_FILENO], context->stdio_fdname[STDERR_FILENO]); + + if (IN_SET(e, EXEC_OUTPUT_FILE, EXEC_OUTPUT_FILE_APPEND, EXEC_OUTPUT_FILE_TRUNCATE)) + return streq_ptr(context->stdio_file[STDOUT_FILENO], context->stdio_file[STDERR_FILENO]); + + return true; +} + +static int setup_output( + const ExecContext *context, + const ExecParameters *params, + int fileno, + int socket_fd, + const int named_iofds[static 3], + const char *ident, + uid_t uid, + gid_t gid, + dev_t *journal_stream_dev, + ino_t *journal_stream_ino) { + + ExecOutput o; + ExecInput i; + int r; + + assert(context); + assert(params); + assert(ident); + assert(journal_stream_dev); + assert(journal_stream_ino); + + if (fileno == STDOUT_FILENO && params->stdout_fd >= 0) { + + if (dup2(params->stdout_fd, STDOUT_FILENO) < 0) + return -errno; + + return STDOUT_FILENO; + } + + if (fileno == STDERR_FILENO && params->stderr_fd >= 0) { + if (dup2(params->stderr_fd, STDERR_FILENO) < 0) + return -errno; + + return STDERR_FILENO; + } + + i = fixup_input(context, socket_fd, params->flags & EXEC_APPLY_TTY_STDIN); + o = fixup_output(context->std_output, socket_fd); + + if (fileno == STDERR_FILENO) { + ExecOutput e; + e = fixup_output(context->std_error, socket_fd); + + /* This expects the input and output are already set up */ + + /* Don't change the stderr file descriptor if we inherit all + * the way and are not on a tty */ + if (e == EXEC_OUTPUT_INHERIT && + o == EXEC_OUTPUT_INHERIT && + i == EXEC_INPUT_NULL && + !is_terminal_input(context->std_input) && + getppid() != 1) + return fileno; + + /* Duplicate from stdout if possible */ + if (can_inherit_stderr_from_stdout(context, o, e)) + return RET_NERRNO(dup2(STDOUT_FILENO, fileno)); + + o = e; + + } else if (o == EXEC_OUTPUT_INHERIT) { + /* If input got downgraded, inherit the original value */ + if (i == EXEC_INPUT_NULL && is_terminal_input(context->std_input)) + return open_terminal_as(exec_context_tty_path(context), O_WRONLY, fileno); + + /* If the input is connected to anything that's not a /dev/null or a data fd, inherit that... */ + if (!IN_SET(i, EXEC_INPUT_NULL, EXEC_INPUT_DATA)) + return RET_NERRNO(dup2(STDIN_FILENO, fileno)); + + /* If we are not started from PID 1 we just inherit STDOUT from our parent process. */ + if (getppid() != 1) + return fileno; + + /* We need to open /dev/null here anew, to get the right access mode. */ + return open_null_as(O_WRONLY, fileno); + } + + switch (o) { + + case EXEC_OUTPUT_NULL: + return open_null_as(O_WRONLY, fileno); + + case EXEC_OUTPUT_TTY: + if (is_terminal_input(i)) + return RET_NERRNO(dup2(STDIN_FILENO, fileno)); + + /* We don't reset the terminal if this is just about output */ + return open_terminal_as(exec_context_tty_path(context), O_WRONLY, fileno); + + case EXEC_OUTPUT_KMSG: + case EXEC_OUTPUT_KMSG_AND_CONSOLE: + case EXEC_OUTPUT_JOURNAL: + case EXEC_OUTPUT_JOURNAL_AND_CONSOLE: + r = connect_logger_as(context, params, o, ident, fileno, uid, gid); + if (r < 0) { + log_exec_warning_errno(context, + params, + r, + "Failed to connect %s to the journal socket, ignoring: %m", + fileno == STDOUT_FILENO ? "stdout" : "stderr"); + r = open_null_as(O_WRONLY, fileno); + } else { + struct stat st; + + /* If we connected this fd to the journal via a stream, patch the device/inode into the passed + * parameters, but only then. This is useful so that we can set $JOURNAL_STREAM that permits + * services to detect whether they are connected to the journal or not. + * + * If both stdout and stderr are connected to a stream then let's make sure to store the data + * about STDERR as that's usually the best way to do logging. */ + + if (fstat(fileno, &st) >= 0 && + (*journal_stream_ino == 0 || fileno == STDERR_FILENO)) { + *journal_stream_dev = st.st_dev; + *journal_stream_ino = st.st_ino; + } + } + return r; + + case EXEC_OUTPUT_SOCKET: + assert(socket_fd >= 0); + + return RET_NERRNO(dup2(socket_fd, fileno)); + + case EXEC_OUTPUT_NAMED_FD: + assert(named_iofds[fileno] >= 0); + + (void) fd_nonblock(named_iofds[fileno], false); + return RET_NERRNO(dup2(named_iofds[fileno], fileno)); + + case EXEC_OUTPUT_FILE: + case EXEC_OUTPUT_FILE_APPEND: + case EXEC_OUTPUT_FILE_TRUNCATE: { + bool rw; + int fd, flags; + + assert(context->stdio_file[fileno]); + + rw = context->std_input == EXEC_INPUT_FILE && + streq_ptr(context->stdio_file[fileno], context->stdio_file[STDIN_FILENO]); + + if (rw) + return RET_NERRNO(dup2(STDIN_FILENO, fileno)); + + flags = O_WRONLY; + if (o == EXEC_OUTPUT_FILE_APPEND) + flags |= O_APPEND; + else if (o == EXEC_OUTPUT_FILE_TRUNCATE) + flags |= O_TRUNC; + + fd = acquire_path(context->stdio_file[fileno], flags, 0666 & ~context->umask); + if (fd < 0) + return fd; + + return move_fd(fd, fileno, 0); + } + + default: + assert_not_reached(); + } +} + +static int chown_terminal(int fd, uid_t uid) { + int r; + + assert(fd >= 0); + + /* Before we chown/chmod the TTY, let's ensure this is actually a tty */ + if (isatty(fd) < 1) { + if (IN_SET(errno, EINVAL, ENOTTY)) + return 0; /* not a tty */ + + return -errno; + } + + /* This might fail. What matters are the results. */ + r = fchmod_and_chown(fd, TTY_MODE, uid, GID_INVALID); + if (r < 0) + return r; + + return 1; +} + +static int setup_confirm_stdio( + const ExecContext *context, + const char *vc, + int *ret_saved_stdin, + int *ret_saved_stdout) { + + _cleanup_close_ int fd = -EBADF, saved_stdin = -EBADF, saved_stdout = -EBADF; + int r; + + assert(ret_saved_stdin); + assert(ret_saved_stdout); + + saved_stdin = fcntl(STDIN_FILENO, F_DUPFD, 3); + if (saved_stdin < 0) + return -errno; + + saved_stdout = fcntl(STDOUT_FILENO, F_DUPFD, 3); + if (saved_stdout < 0) + return -errno; + + fd = acquire_terminal(vc, ACQUIRE_TERMINAL_WAIT, DEFAULT_CONFIRM_USEC); + if (fd < 0) + return fd; + + r = chown_terminal(fd, getuid()); + if (r < 0) + return r; + + r = reset_terminal_fd(fd, /* switch_to_text= */ true); + if (r < 0) + return r; + + r = exec_context_apply_tty_size(context, fd, vc); + if (r < 0) + return r; + + r = rearrange_stdio(fd, fd, STDERR_FILENO); /* Invalidates 'fd' also on failure */ + TAKE_FD(fd); + if (r < 0) + return r; + + *ret_saved_stdin = TAKE_FD(saved_stdin); + *ret_saved_stdout = TAKE_FD(saved_stdout); + return 0; +} + +static void write_confirm_error_fd(int err, int fd, const char *unit_id) { + assert(err < 0); + assert(unit_id); + + if (err == -ETIMEDOUT) + dprintf(fd, "Confirmation question timed out for %s, assuming positive response.\n", unit_id); + else { + errno = -err; + dprintf(fd, "Couldn't ask confirmation for %s: %m, assuming positive response.\n", unit_id); + } +} + +static void write_confirm_error(int err, const char *vc, const char *unit_id) { + _cleanup_close_ int fd = -EBADF; + + assert(vc); + + fd = open_terminal(vc, O_WRONLY|O_NOCTTY|O_CLOEXEC); + if (fd < 0) + return; + + write_confirm_error_fd(err, fd, unit_id); +} + +static int restore_confirm_stdio(int *saved_stdin, int *saved_stdout) { + int r = 0; + + assert(saved_stdin); + assert(saved_stdout); + + release_terminal(); + + if (*saved_stdin >= 0) + if (dup2(*saved_stdin, STDIN_FILENO) < 0) + r = -errno; + + if (*saved_stdout >= 0) + if (dup2(*saved_stdout, STDOUT_FILENO) < 0) + r = -errno; + + *saved_stdin = safe_close(*saved_stdin); + *saved_stdout = safe_close(*saved_stdout); + + return r; +} + +enum { + CONFIRM_PRETEND_FAILURE = -1, + CONFIRM_PRETEND_SUCCESS = 0, + CONFIRM_EXECUTE = 1, +}; + +static bool confirm_spawn_disabled(void) { + return access("/run/systemd/confirm_spawn_disabled", F_OK) >= 0; +} + +static int ask_for_confirmation(const ExecContext *context, const ExecParameters *params, const char *cmdline) { + int saved_stdout = -1, saved_stdin = -1, r; + _cleanup_free_ char *e = NULL; + char c; + + assert(context); + assert(params); + + /* For any internal errors, assume a positive response. */ + r = setup_confirm_stdio(context, params->confirm_spawn, &saved_stdin, &saved_stdout); + if (r < 0) { + write_confirm_error(r, params->confirm_spawn, params->unit_id); + return CONFIRM_EXECUTE; + } + + /* confirm_spawn might have been disabled while we were sleeping. */ + if (!params->confirm_spawn || confirm_spawn_disabled()) { + r = 1; + goto restore_stdio; + } + + e = ellipsize(cmdline, 60, 100); + if (!e) { + log_oom(); + r = CONFIRM_EXECUTE; + goto restore_stdio; + } + + for (;;) { + r = ask_char(&c, "yfshiDjcn", "Execute %s? [y, f, s – h for help] ", e); + if (r < 0) { + write_confirm_error_fd(r, STDOUT_FILENO, params->unit_id); + r = CONFIRM_EXECUTE; + goto restore_stdio; + } + + switch (c) { + case 'c': + printf("Resuming normal execution.\n"); + manager_disable_confirm_spawn(); + r = 1; + break; + case 'D': + printf(" Unit: %s\n", + params->unit_id); + exec_context_dump(context, stdout, " "); + exec_params_dump(params, stdout, " "); + continue; /* ask again */ + case 'f': + printf("Failing execution.\n"); + r = CONFIRM_PRETEND_FAILURE; + break; + case 'h': + printf(" c - continue, proceed without asking anymore\n" + " D - dump, show the state of the unit\n" + " f - fail, don't execute the command and pretend it failed\n" + " h - help\n" + " i - info, show a short summary of the unit\n" + " j - jobs, show jobs that are in progress\n" + " s - skip, don't execute the command and pretend it succeeded\n" + " y - yes, execute the command\n"); + continue; /* ask again */ + case 'i': + printf(" Unit: %s\n" + " Command: %s\n", + params->unit_id, cmdline); + continue; /* ask again */ + case 'j': + if (sigqueue(getppid(), + SIGRTMIN+18, + (const union sigval) { .sival_int = MANAGER_SIGNAL_COMMAND_DUMP_JOBS }) < 0) + return -errno; + + continue; /* ask again */ + case 'n': + /* 'n' was removed in favor of 'f'. */ + printf("Didn't understand 'n', did you mean 'f'?\n"); + continue; /* ask again */ + case 's': + printf("Skipping execution.\n"); + r = CONFIRM_PRETEND_SUCCESS; + break; + case 'y': + r = CONFIRM_EXECUTE; + break; + default: + assert_not_reached(); + } + break; + } + +restore_stdio: + restore_confirm_stdio(&saved_stdin, &saved_stdout); + return r; +} + +static int get_fixed_user( + const char *user_or_uid, + const char **ret_username, + uid_t *ret_uid, + gid_t *ret_gid, + const char **ret_home, + const char **ret_shell) { + + int r; + + assert(user_or_uid); + assert(ret_username); + + /* Note that we don't set $HOME or $SHELL if they are not particularly enlightening anyway + * (i.e. are "/" or "/bin/nologin"). */ + + r = get_user_creds(&user_or_uid, ret_uid, ret_gid, ret_home, ret_shell, USER_CREDS_CLEAN); + if (r < 0) + return r; + + /* user_or_uid is normalized by get_user_creds to username */ + *ret_username = user_or_uid; + + return 0; +} + +static int get_fixed_group( + const char *group_or_gid, + const char **ret_groupname, + gid_t *ret_gid) { + + int r; + + assert(group_or_gid); + assert(ret_groupname); + + r = get_group_creds(&group_or_gid, ret_gid, /* flags = */ 0); + if (r < 0) + return r; + + /* group_or_gid is normalized by get_group_creds to groupname */ + *ret_groupname = group_or_gid; + + return 0; +} + +static int get_supplementary_groups(const ExecContext *c, const char *user, + const char *group, gid_t gid, + gid_t **supplementary_gids, int *ngids) { + int r, k = 0; + int ngroups_max; + bool keep_groups = false; + gid_t *groups = NULL; + _cleanup_free_ gid_t *l_gids = NULL; + + assert(c); + + /* + * If user is given, then lookup GID and supplementary groups list. + * We avoid NSS lookups for gid=0. Also we have to initialize groups + * here and as early as possible so we keep the list of supplementary + * groups of the caller. + */ + if (user && gid_is_valid(gid) && gid != 0) { + /* First step, initialize groups from /etc/groups */ + if (initgroups(user, gid) < 0) + return -errno; + + keep_groups = true; + } + + if (strv_isempty(c->supplementary_groups)) + return 0; + + /* + * If SupplementaryGroups= was passed then NGROUPS_MAX has to + * be positive, otherwise fail. + */ + errno = 0; + ngroups_max = (int) sysconf(_SC_NGROUPS_MAX); + if (ngroups_max <= 0) + return errno_or_else(EOPNOTSUPP); + + l_gids = new(gid_t, ngroups_max); + if (!l_gids) + return -ENOMEM; + + if (keep_groups) { + /* + * Lookup the list of groups that the user belongs to, we + * avoid NSS lookups here too for gid=0. + */ + k = ngroups_max; + if (getgrouplist(user, gid, l_gids, &k) < 0) + return -EINVAL; + } else + k = 0; + + STRV_FOREACH(i, c->supplementary_groups) { + const char *g; + + if (k >= ngroups_max) + return -E2BIG; + + g = *i; + r = get_group_creds(&g, l_gids+k, 0); + if (r < 0) + return r; + + k++; + } + + /* + * Sets ngids to zero to drop all supplementary groups, happens + * when we are under root and SupplementaryGroups= is empty. + */ + if (k == 0) { + *ngids = 0; + return 0; + } + + /* Otherwise get the final list of supplementary groups */ + groups = memdup(l_gids, sizeof(gid_t) * k); + if (!groups) + return -ENOMEM; + + *supplementary_gids = groups; + *ngids = k; + + groups = NULL; + + return 0; +} + +static int enforce_groups(gid_t gid, const gid_t *supplementary_gids, int ngids) { + int r; + + /* Handle SupplementaryGroups= if it is not empty */ + if (ngids > 0) { + r = maybe_setgroups(ngids, supplementary_gids); + if (r < 0) + return r; + } + + if (gid_is_valid(gid)) { + /* Then set our gids */ + if (setresgid(gid, gid, gid) < 0) + return -errno; + } + + return 0; +} + +static int set_securebits(unsigned bits, unsigned mask) { + unsigned applied; + int current; + + current = prctl(PR_GET_SECUREBITS); + if (current < 0) + return -errno; + + /* Clear all securebits defined in mask and set bits */ + applied = ((unsigned) current & ~mask) | bits; + if ((unsigned) current == applied) + return 0; + + if (prctl(PR_SET_SECUREBITS, applied) < 0) + return -errno; + + return 1; +} + +static int enforce_user( + const ExecContext *context, + uid_t uid, + uint64_t capability_ambient_set) { + assert(context); + int r; + + if (!uid_is_valid(uid)) + return 0; + + /* Sets (but doesn't look up) the UIS and makes sure we keep the capabilities while doing so. For + * setting secure bits the capability CAP_SETPCAP is required, so we also need keep-caps in this + * case. */ + + if ((capability_ambient_set != 0 || context->secure_bits != 0) && uid != 0) { + + /* First step: If we need to keep capabilities but drop privileges we need to make sure we + * keep our caps, while we drop privileges. Add KEEP_CAPS to the securebits */ + r = set_securebits(1U << SECURE_KEEP_CAPS, 0); + if (r < 0) + return r; + } + + /* Second step: actually set the uids */ + if (setresuid(uid, uid, uid) < 0) + return -errno; + + /* At this point we should have all necessary capabilities but are otherwise a normal user. However, + * the caps might got corrupted due to the setresuid() so we need clean them up later. This is done + * outside of this call. */ + return 0; +} + +#if HAVE_PAM + +static int null_conv( + int num_msg, + const struct pam_message **msg, + struct pam_response **resp, + void *appdata_ptr) { + + /* We don't support conversations */ + + return PAM_CONV_ERR; +} + +static int pam_close_session_and_delete_credentials(pam_handle_t *handle, int flags) { + int r, s; + + assert(handle); + + r = pam_close_session(handle, flags); + if (r != PAM_SUCCESS) + log_debug("pam_close_session() failed: %s", pam_strerror(handle, r)); + + s = pam_setcred(handle, PAM_DELETE_CRED | flags); + if (s != PAM_SUCCESS) + log_debug("pam_setcred(PAM_DELETE_CRED) failed: %s", pam_strerror(handle, s)); + + return r != PAM_SUCCESS ? r : s; +} + +#endif + +static int setup_pam( + const char *name, + const char *user, + uid_t uid, + gid_t gid, + const char *tty, + char ***env, /* updated on success */ + const int fds[], size_t n_fds) { + +#if HAVE_PAM + + static const struct pam_conv conv = { + .conv = null_conv, + .appdata_ptr = NULL + }; + + _cleanup_(barrier_destroy) Barrier barrier = BARRIER_NULL; + _cleanup_strv_free_ char **e = NULL; + pam_handle_t *handle = NULL; + sigset_t old_ss; + int pam_code = PAM_SUCCESS, r; + bool close_session = false; + pid_t pam_pid = 0, parent_pid; + int flags = 0; + + assert(name); + assert(user); + assert(env); + + /* We set up PAM in the parent process, then fork. The child + * will then stay around until killed via PR_GET_PDEATHSIG or + * systemd via the cgroup logic. It will then remove the PAM + * session again. The parent process will exec() the actual + * daemon. We do things this way to ensure that the main PID + * of the daemon is the one we initially fork()ed. */ + + r = barrier_create(&barrier); + if (r < 0) + goto fail; + + if (log_get_max_level() < LOG_DEBUG) + flags |= PAM_SILENT; + + pam_code = pam_start(name, user, &conv, &handle); + if (pam_code != PAM_SUCCESS) { + handle = NULL; + goto fail; + } + + if (!tty) { + _cleanup_free_ char *q = NULL; + + /* Hmm, so no TTY was explicitly passed, but an fd passed to us directly might be a TTY. Let's figure + * out if that's the case, and read the TTY off it. */ + + if (getttyname_malloc(STDIN_FILENO, &q) >= 0) + tty = strjoina("/dev/", q); + } + + if (tty) { + pam_code = pam_set_item(handle, PAM_TTY, tty); + if (pam_code != PAM_SUCCESS) + goto fail; + } + + STRV_FOREACH(nv, *env) { + pam_code = pam_putenv(handle, *nv); + if (pam_code != PAM_SUCCESS) + goto fail; + } + + pam_code = pam_acct_mgmt(handle, flags); + if (pam_code != PAM_SUCCESS) + goto fail; + + pam_code = pam_setcred(handle, PAM_ESTABLISH_CRED | flags); + if (pam_code != PAM_SUCCESS) + log_debug("pam_setcred() failed, ignoring: %s", pam_strerror(handle, pam_code)); + + pam_code = pam_open_session(handle, flags); + if (pam_code != PAM_SUCCESS) + goto fail; + + close_session = true; + + e = pam_getenvlist(handle); + if (!e) { + pam_code = PAM_BUF_ERR; + goto fail; + } + + /* Block SIGTERM, so that we know that it won't get lost in the child */ + + assert_se(sigprocmask_many(SIG_BLOCK, &old_ss, SIGTERM, -1) >= 0); + + parent_pid = getpid_cached(); + + r = safe_fork("(sd-pam)", 0, &pam_pid); + if (r < 0) + goto fail; + if (r == 0) { + int sig, ret = EXIT_PAM; + + /* The child's job is to reset the PAM session on termination */ + barrier_set_role(&barrier, BARRIER_CHILD); + + /* Make sure we don't keep open the passed fds in this child. We assume that otherwise only + * those fds are open here that have been opened by PAM. */ + (void) close_many(fds, n_fds); + + /* Drop privileges - we don't need any to pam_close_session and this will make + * PR_SET_PDEATHSIG work in most cases. If this fails, ignore the error - but expect sd-pam + * threads to fail to exit normally */ + + r = maybe_setgroups(0, NULL); + if (r < 0) + log_warning_errno(r, "Failed to setgroups() in sd-pam: %m"); + if (setresgid(gid, gid, gid) < 0) + log_warning_errno(errno, "Failed to setresgid() in sd-pam: %m"); + if (setresuid(uid, uid, uid) < 0) + log_warning_errno(errno, "Failed to setresuid() in sd-pam: %m"); + + (void) ignore_signals(SIGPIPE); + + /* Wait until our parent died. This will only work if the above setresuid() succeeds, + * otherwise the kernel will not allow unprivileged parents kill their privileged children + * this way. We rely on the control groups kill logic to do the rest for us. */ + if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) + goto child_finish; + + /* Tell the parent that our setup is done. This is especially important regarding dropping + * privileges. Otherwise, unit setup might race against our setresuid(2) call. + * + * If the parent aborted, we'll detect this below, hence ignore return failure here. */ + (void) barrier_place(&barrier); + + /* Check if our parent process might already have died? */ + if (getppid() == parent_pid) { + sigset_t ss; + + assert_se(sigemptyset(&ss) >= 0); + assert_se(sigaddset(&ss, SIGTERM) >= 0); + + for (;;) { + if (sigwait(&ss, &sig) < 0) { + if (errno == EINTR) + continue; + + goto child_finish; + } + + assert(sig == SIGTERM); + break; + } + } + + /* If our parent died we'll end the session */ + if (getppid() != parent_pid) { + pam_code = pam_close_session_and_delete_credentials(handle, flags); + if (pam_code != PAM_SUCCESS) + goto child_finish; + } + + ret = 0; + + child_finish: + /* NB: pam_end() when called in child processes should set PAM_DATA_SILENT to let the module + * know about this. See pam_end(3) */ + (void) pam_end(handle, pam_code | flags | PAM_DATA_SILENT); + _exit(ret); + } + + barrier_set_role(&barrier, BARRIER_PARENT); + + /* If the child was forked off successfully it will do all the cleanups, so forget about the handle + * here. */ + handle = NULL; + + /* Unblock SIGTERM again in the parent */ + assert_se(sigprocmask(SIG_SETMASK, &old_ss, NULL) >= 0); + + /* We close the log explicitly here, since the PAM modules might have opened it, but we don't want + * this fd around. */ + closelog(); + + /* Synchronously wait for the child to initialize. We don't care for errors as we cannot + * recover. However, warn loudly if it happens. */ + if (!barrier_place_and_sync(&barrier)) + log_error("PAM initialization failed"); + + return strv_free_and_replace(*env, e); + +fail: + if (pam_code != PAM_SUCCESS) { + log_error("PAM failed: %s", pam_strerror(handle, pam_code)); + r = -EPERM; /* PAM errors do not map to errno */ + } else + log_error_errno(r, "PAM failed: %m"); + + if (handle) { + if (close_session) + pam_code = pam_close_session_and_delete_credentials(handle, flags); + + (void) pam_end(handle, pam_code | flags); + } + + closelog(); + return r; +#else + return 0; +#endif +} + +static void rename_process_from_path(const char *path) { + _cleanup_free_ char *buf = NULL; + const char *p; + + assert(path); + + /* This resulting string must fit in 10 chars (i.e. the length of "/sbin/init") to look pretty in + * /bin/ps */ + + if (path_extract_filename(path, &buf) < 0) { + rename_process("(...)"); + return; + } + + size_t l = strlen(buf); + if (l > 8) { + /* The end of the process name is usually more interesting, since the first bit might just be + * "systemd-" */ + p = buf + l - 8; + l = 8; + } else + p = buf; + + char process_name[11]; + process_name[0] = '('; + memcpy(process_name+1, p, l); + process_name[1+l] = ')'; + process_name[1+l+1] = 0; + + rename_process(process_name); +} + +static bool context_has_address_families(const ExecContext *c) { + assert(c); + + return c->address_families_allow_list || + !set_isempty(c->address_families); +} + +static bool context_has_syscall_filters(const ExecContext *c) { + assert(c); + + return c->syscall_allow_list || + !hashmap_isempty(c->syscall_filter); +} + +static bool context_has_syscall_logs(const ExecContext *c) { + assert(c); + + return c->syscall_log_allow_list || + !hashmap_isempty(c->syscall_log); +} + +static bool context_has_seccomp(const ExecContext *c) { + /* We need NNP if we have any form of seccomp and are unprivileged */ + return c->lock_personality || + c->memory_deny_write_execute || + c->private_devices || + c->protect_clock || + c->protect_hostname || + c->protect_kernel_tunables || + c->protect_kernel_modules || + c->protect_kernel_logs || + context_has_address_families(c) || + exec_context_restrict_namespaces_set(c) || + c->restrict_realtime || + c->restrict_suid_sgid || + !set_isempty(c->syscall_archs) || + context_has_syscall_filters(c) || + context_has_syscall_logs(c); +} + +static bool context_has_no_new_privileges(const ExecContext *c) { + assert(c); + + if (c->no_new_privileges) + return true; + + if (have_effective_cap(CAP_SYS_ADMIN) > 0) /* if we are privileged, we don't need NNP */ + return false; + + return context_has_seccomp(c); +} + +#if HAVE_SECCOMP + +static bool seccomp_allows_drop_privileges(const ExecContext *c) { + void *id, *val; + bool has_capget = false, has_capset = false, has_prctl = false; + + assert(c); + + /* No syscall filter, we are allowed to drop privileges */ + if (hashmap_isempty(c->syscall_filter)) + return true; + + HASHMAP_FOREACH_KEY(val, id, c->syscall_filter) { + _cleanup_free_ char *name = NULL; + + name = seccomp_syscall_resolve_num_arch(SCMP_ARCH_NATIVE, PTR_TO_INT(id) - 1); + + if (streq(name, "capget")) + has_capget = true; + else if (streq(name, "capset")) + has_capset = true; + else if (streq(name, "prctl")) + has_prctl = true; + } + + if (c->syscall_allow_list) + return has_capget && has_capset && has_prctl; + else + return !(has_capget || has_capset || has_prctl); +} + +static bool skip_seccomp_unavailable(const ExecContext *c, const ExecParameters *p, const char* msg) { + + if (is_seccomp_available()) + return false; + + log_exec_debug(c, p, "SECCOMP features not detected in the kernel, skipping %s", msg); + return true; +} + +static int apply_syscall_filter(const ExecContext *c, const ExecParameters *p, bool needs_ambient_hack) { + uint32_t negative_action, default_action, action; + int r; + + assert(c); + assert(p); + + if (!context_has_syscall_filters(c)) + return 0; + + if (skip_seccomp_unavailable(c, p, "SystemCallFilter=")) + return 0; + + negative_action = c->syscall_errno == SECCOMP_ERROR_NUMBER_KILL ? scmp_act_kill_process() : SCMP_ACT_ERRNO(c->syscall_errno); + + if (c->syscall_allow_list) { + default_action = negative_action; + action = SCMP_ACT_ALLOW; + } else { + default_action = SCMP_ACT_ALLOW; + action = negative_action; + } + + if (needs_ambient_hack) { + r = seccomp_filter_set_add(c->syscall_filter, c->syscall_allow_list, syscall_filter_sets + SYSCALL_FILTER_SET_SETUID); + if (r < 0) + return r; + } + + return seccomp_load_syscall_filter_set_raw(default_action, c->syscall_filter, action, false); +} + +static int apply_syscall_log(const ExecContext *c, const ExecParameters *p) { +#ifdef SCMP_ACT_LOG + uint32_t default_action, action; +#endif + + assert(c); + assert(p); + + if (!context_has_syscall_logs(c)) + return 0; + +#ifdef SCMP_ACT_LOG + if (skip_seccomp_unavailable(c, p, "SystemCallLog=")) + return 0; + + if (c->syscall_log_allow_list) { + /* Log nothing but the ones listed */ + default_action = SCMP_ACT_ALLOW; + action = SCMP_ACT_LOG; + } else { + /* Log everything but the ones listed */ + default_action = SCMP_ACT_LOG; + action = SCMP_ACT_ALLOW; + } + + return seccomp_load_syscall_filter_set_raw(default_action, c->syscall_log, action, false); +#else + /* old libseccomp */ + log_exec_debug(c, p, "SECCOMP feature SCMP_ACT_LOG not available, skipping SystemCallLog="); + return 0; +#endif +} + +static int apply_syscall_archs(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + if (set_isempty(c->syscall_archs)) + return 0; + + if (skip_seccomp_unavailable(c, p, "SystemCallArchitectures=")) + return 0; + + return seccomp_restrict_archs(c->syscall_archs); +} + +static int apply_address_families(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + if (!context_has_address_families(c)) + return 0; + + if (skip_seccomp_unavailable(c, p, "RestrictAddressFamilies=")) + return 0; + + return seccomp_restrict_address_families(c->address_families, c->address_families_allow_list); +} + +static int apply_memory_deny_write_execute(const ExecContext *c, const ExecParameters *p) { + int r; + + assert(c); + assert(p); + + if (!c->memory_deny_write_execute) + return 0; + + /* use prctl() if kernel supports it (6.3) */ + r = prctl(PR_SET_MDWE, PR_MDWE_REFUSE_EXEC_GAIN, 0, 0, 0); + if (r == 0) { + log_exec_debug(c, p, "Enabled MemoryDenyWriteExecute= with PR_SET_MDWE"); + return 0; + } + if (r < 0 && errno != EINVAL) + return log_exec_debug_errno(c, + p, + errno, + "Failed to enable MemoryDenyWriteExecute= with PR_SET_MDWE: %m"); + /* else use seccomp */ + log_exec_debug(c, p, "Kernel doesn't support PR_SET_MDWE: falling back to seccomp"); + + if (skip_seccomp_unavailable(c, p, "MemoryDenyWriteExecute=")) + return 0; + + return seccomp_memory_deny_write_execute(); +} + +static int apply_restrict_realtime(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + if (!c->restrict_realtime) + return 0; + + if (skip_seccomp_unavailable(c, p, "RestrictRealtime=")) + return 0; + + return seccomp_restrict_realtime(); +} + +static int apply_restrict_suid_sgid(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + if (!c->restrict_suid_sgid) + return 0; + + if (skip_seccomp_unavailable(c, p, "RestrictSUIDSGID=")) + return 0; + + return seccomp_restrict_suid_sgid(); +} + +static int apply_protect_sysctl(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + /* Turn off the legacy sysctl() system call. Many distributions turn this off while building the kernel, but + * let's protect even those systems where this is left on in the kernel. */ + + if (!c->protect_kernel_tunables) + return 0; + + if (skip_seccomp_unavailable(c, p, "ProtectKernelTunables=")) + return 0; + + return seccomp_protect_sysctl(); +} + +static int apply_protect_kernel_modules(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + /* Turn off module syscalls on ProtectKernelModules=yes */ + + if (!c->protect_kernel_modules) + return 0; + + if (skip_seccomp_unavailable(c, p, "ProtectKernelModules=")) + return 0; + + return seccomp_load_syscall_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_MODULE, SCMP_ACT_ERRNO(EPERM), false); +} + +static int apply_protect_kernel_logs(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + if (!c->protect_kernel_logs) + return 0; + + if (skip_seccomp_unavailable(c, p, "ProtectKernelLogs=")) + return 0; + + return seccomp_protect_syslog(); +} + +static int apply_protect_clock(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + if (!c->protect_clock) + return 0; + + if (skip_seccomp_unavailable(c, p, "ProtectClock=")) + return 0; + + return seccomp_load_syscall_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_CLOCK, SCMP_ACT_ERRNO(EPERM), false); +} + +static int apply_private_devices(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + /* If PrivateDevices= is set, also turn off iopl and all @raw-io syscalls. */ + + if (!c->private_devices) + return 0; + + if (skip_seccomp_unavailable(c, p, "PrivateDevices=")) + return 0; + + return seccomp_load_syscall_filter_set(SCMP_ACT_ALLOW, syscall_filter_sets + SYSCALL_FILTER_SET_RAW_IO, SCMP_ACT_ERRNO(EPERM), false); +} + +static int apply_restrict_namespaces(const ExecContext *c, const ExecParameters *p) { + assert(c); + assert(p); + + if (!exec_context_restrict_namespaces_set(c)) + return 0; + + if (skip_seccomp_unavailable(c, p, "RestrictNamespaces=")) + return 0; + + return seccomp_restrict_namespaces(c->restrict_namespaces); +} + +static int apply_lock_personality(const ExecContext *c, const ExecParameters *p) { + unsigned long personality; + int r; + + assert(c); + assert(p); + + if (!c->lock_personality) + return 0; + + if (skip_seccomp_unavailable(c, p, "LockPersonality=")) + return 0; + + personality = c->personality; + + /* If personality is not specified, use either PER_LINUX or PER_LINUX32 depending on what is currently set. */ + if (personality == PERSONALITY_INVALID) { + + r = opinionated_personality(&personality); + if (r < 0) + return r; + } + + return seccomp_lock_personality(personality); +} + +#endif + +#if HAVE_LIBBPF +static int apply_restrict_filesystems(const ExecContext *c, const ExecParameters *p) { + int r; + + assert(c); + assert(p); + + if (!exec_context_restrict_filesystems_set(c)) + return 0; + + if (p->bpf_outer_map_fd < 0) { + /* LSM BPF is unsupported or lsm_bpf_setup failed */ + log_exec_debug(c, p, "LSM BPF not supported, skipping RestrictFileSystems="); + return 0; + } + + /* We are in a new binary, so dl-open again */ + r = dlopen_bpf(); + if (r < 0) + return r; + + return lsm_bpf_restrict_filesystems(c->restrict_filesystems, p->cgroup_id, p->bpf_outer_map_fd, c->restrict_filesystems_allow_list); +} +#endif + +static int apply_protect_hostname(const ExecContext *c, const ExecParameters *p, int *ret_exit_status) { + assert(c); + assert(p); + + if (!c->protect_hostname) + return 0; + + if (ns_type_supported(NAMESPACE_UTS)) { + if (unshare(CLONE_NEWUTS) < 0) { + if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno)) { + *ret_exit_status = EXIT_NAMESPACE; + return log_exec_error_errno(c, + p, + errno, + "Failed to set up UTS namespacing: %m"); + } + + log_exec_warning(c, + p, + "ProtectHostname=yes is configured, but UTS namespace setup is " + "prohibited (container manager?), ignoring namespace setup."); + } + } else + log_exec_warning(c, + p, + "ProtectHostname=yes is configured, but the kernel does not " + "support UTS namespaces, ignoring namespace setup."); + +#if HAVE_SECCOMP + int r; + + if (skip_seccomp_unavailable(c, p, "ProtectHostname=")) + return 0; + + r = seccomp_protect_hostname(); + if (r < 0) { + *ret_exit_status = EXIT_SECCOMP; + return log_exec_error_errno(c, p, r, "Failed to apply hostname restrictions: %m"); + } +#endif + + return 0; +} + +static void do_idle_pipe_dance(int idle_pipe[static 4]) { + assert(idle_pipe); + + idle_pipe[1] = safe_close(idle_pipe[1]); + idle_pipe[2] = safe_close(idle_pipe[2]); + + if (idle_pipe[0] >= 0) { + int r; + + r = fd_wait_for_event(idle_pipe[0], POLLHUP, IDLE_TIMEOUT_USEC); + + if (idle_pipe[3] >= 0 && r == 0 /* timeout */) { + ssize_t n; + + /* Signal systemd that we are bored and want to continue. */ + n = write(idle_pipe[3], "x", 1); + if (n > 0) + /* Wait for systemd to react to the signal above. */ + (void) fd_wait_for_event(idle_pipe[0], POLLHUP, IDLE_TIMEOUT2_USEC); + } + + idle_pipe[0] = safe_close(idle_pipe[0]); + + } + + idle_pipe[3] = safe_close(idle_pipe[3]); +} + +static const char *exec_directory_env_name_to_string(ExecDirectoryType t); + +/* And this table also maps ExecDirectoryType, to the environment variable we pass the selected directory to + * the service payload in. */ +static const char* const exec_directory_env_name_table[_EXEC_DIRECTORY_TYPE_MAX] = { + [EXEC_DIRECTORY_RUNTIME] = "RUNTIME_DIRECTORY", + [EXEC_DIRECTORY_STATE] = "STATE_DIRECTORY", + [EXEC_DIRECTORY_CACHE] = "CACHE_DIRECTORY", + [EXEC_DIRECTORY_LOGS] = "LOGS_DIRECTORY", + [EXEC_DIRECTORY_CONFIGURATION] = "CONFIGURATION_DIRECTORY", +}; + +DEFINE_PRIVATE_STRING_TABLE_LOOKUP_TO_STRING(exec_directory_env_name, ExecDirectoryType); + +static int build_environment( + const ExecContext *c, + const ExecParameters *p, + const CGroupContext *cgroup_context, + size_t n_fds, + const char *home, + const char *username, + const char *shell, + dev_t journal_stream_dev, + ino_t journal_stream_ino, + const char *memory_pressure_path, + char ***ret) { + + _cleanup_strv_free_ char **our_env = NULL; + size_t n_env = 0; + char *x; + int r; + + assert(c); + assert(p); + assert(ret); + +#define N_ENV_VARS 19 + our_env = new0(char*, N_ENV_VARS + _EXEC_DIRECTORY_TYPE_MAX); + if (!our_env) + return -ENOMEM; + + if (n_fds > 0) { + _cleanup_free_ char *joined = NULL; + + if (asprintf(&x, "LISTEN_PID="PID_FMT, getpid_cached()) < 0) + return -ENOMEM; + our_env[n_env++] = x; + + if (asprintf(&x, "LISTEN_FDS=%zu", n_fds) < 0) + return -ENOMEM; + our_env[n_env++] = x; + + joined = strv_join(p->fd_names, ":"); + if (!joined) + return -ENOMEM; + + x = strjoin("LISTEN_FDNAMES=", joined); + if (!x) + return -ENOMEM; + our_env[n_env++] = x; + } + + if ((p->flags & EXEC_SET_WATCHDOG) && p->watchdog_usec > 0) { + if (asprintf(&x, "WATCHDOG_PID="PID_FMT, getpid_cached()) < 0) + return -ENOMEM; + our_env[n_env++] = x; + + if (asprintf(&x, "WATCHDOG_USEC="USEC_FMT, p->watchdog_usec) < 0) + return -ENOMEM; + our_env[n_env++] = x; + } + + /* If this is D-Bus, tell the nss-systemd module, since it relies on being able to use blocking + * Varlink calls back to us for look up dynamic users in PID 1. Break the deadlock between D-Bus and + * PID 1 by disabling use of PID1' NSS interface for looking up dynamic users. */ + if (p->flags & EXEC_NSS_DYNAMIC_BYPASS) { + x = strdup("SYSTEMD_NSS_DYNAMIC_BYPASS=1"); + if (!x) + return -ENOMEM; + our_env[n_env++] = x; + } + + /* We query "root" if this is a system unit and User= is not specified. $USER is always set. $HOME + * could cause problem for e.g. getty, since login doesn't override $HOME, and $LOGNAME and $SHELL don't + * really make much sense since we're not logged in. Hence we conditionalize the three based on + * SetLoginEnvironment= switch. */ + if (!c->user && !c->dynamic_user && p->runtime_scope == RUNTIME_SCOPE_SYSTEM) { + r = get_fixed_user("root", &username, NULL, NULL, &home, &shell); + if (r < 0) + return log_exec_debug_errno(c, + p, + r, + "Failed to determine user credentials for root: %m"); + } + + bool set_user_login_env = c->set_login_environment >= 0 ? c->set_login_environment : (c->user || c->dynamic_user); + + if (username) { + x = strjoin("USER=", username); + if (!x) + return -ENOMEM; + our_env[n_env++] = x; + + if (set_user_login_env) { + x = strjoin("LOGNAME=", username); + if (!x) + return -ENOMEM; + our_env[n_env++] = x; + } + } + + if (home && set_user_login_env) { + x = strjoin("HOME=", home); + if (!x) + return -ENOMEM; + + path_simplify(x + 5); + our_env[n_env++] = x; + } + + if (shell && set_user_login_env) { + x = strjoin("SHELL=", shell); + if (!x) + return -ENOMEM; + + path_simplify(x + 6); + our_env[n_env++] = x; + } + + if (!sd_id128_is_null(p->invocation_id)) { + assert(p->invocation_id_string); + + x = strjoin("INVOCATION_ID=", p->invocation_id_string); + if (!x) + return -ENOMEM; + + our_env[n_env++] = x; + } + + if (exec_context_needs_term(c)) { + _cleanup_free_ char *cmdline = NULL; + const char *tty_path, *term = NULL; + + tty_path = exec_context_tty_path(c); + + /* If we are forked off PID 1 and we are supposed to operate on /dev/console, then let's try + * to inherit the $TERM set for PID 1. This is useful for containers so that the $TERM the + * container manager passes to PID 1 ends up all the way in the console login shown. */ + + if (path_equal_ptr(tty_path, "/dev/console") && getppid() == 1) + term = getenv("TERM"); + else if (tty_path && in_charset(skip_dev_prefix(tty_path), ALPHANUMERICAL)) { + _cleanup_free_ char *key = NULL; + + key = strjoin("systemd.tty.term.", skip_dev_prefix(tty_path)); + if (!key) + return -ENOMEM; + + r = proc_cmdline_get_key(key, 0, &cmdline); + if (r < 0) + log_exec_debug_errno(c, + p, + r, + "Failed to read %s from kernel cmdline, ignoring: %m", + key); + else if (r > 0) + term = cmdline; + } + + if (!term) + term = default_term_for_tty(tty_path); + + x = strjoin("TERM=", term); + if (!x) + return -ENOMEM; + our_env[n_env++] = x; + } + + if (journal_stream_dev != 0 && journal_stream_ino != 0) { + if (asprintf(&x, "JOURNAL_STREAM=" DEV_FMT ":" INO_FMT, journal_stream_dev, journal_stream_ino) < 0) + return -ENOMEM; + + our_env[n_env++] = x; + } + + if (c->log_namespace) { + x = strjoin("LOG_NAMESPACE=", c->log_namespace); + if (!x) + return -ENOMEM; + + our_env[n_env++] = x; + } + + for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) { + _cleanup_free_ char *joined = NULL; + const char *n; + + if (!p->prefix[t]) + continue; + + if (c->directories[t].n_items == 0) + continue; + + n = exec_directory_env_name_to_string(t); + if (!n) + continue; + + for (size_t i = 0; i < c->directories[t].n_items; i++) { + _cleanup_free_ char *prefixed = NULL; + + prefixed = path_join(p->prefix[t], c->directories[t].items[i].path); + if (!prefixed) + return -ENOMEM; + + if (!strextend_with_separator(&joined, ":", prefixed)) + return -ENOMEM; + } + + x = strjoin(n, "=", joined); + if (!x) + return -ENOMEM; + + our_env[n_env++] = x; + } + + _cleanup_free_ char *creds_dir = NULL; + r = exec_context_get_credential_directory(c, p, p->unit_id, &creds_dir); + if (r < 0) + return r; + if (r > 0) { + x = strjoin("CREDENTIALS_DIRECTORY=", creds_dir); + if (!x) + return -ENOMEM; + + our_env[n_env++] = x; + } + + if (asprintf(&x, "SYSTEMD_EXEC_PID=" PID_FMT, getpid_cached()) < 0) + return -ENOMEM; + + our_env[n_env++] = x; + + if (memory_pressure_path) { + x = strjoin("MEMORY_PRESSURE_WATCH=", memory_pressure_path); + if (!x) + return -ENOMEM; + + our_env[n_env++] = x; + + if (cgroup_context && !path_equal(memory_pressure_path, "/dev/null")) { + _cleanup_free_ char *b = NULL, *e = NULL; + + if (asprintf(&b, "%s " USEC_FMT " " USEC_FMT, + MEMORY_PRESSURE_DEFAULT_TYPE, + cgroup_context->memory_pressure_threshold_usec == USEC_INFINITY ? MEMORY_PRESSURE_DEFAULT_THRESHOLD_USEC : + CLAMP(cgroup_context->memory_pressure_threshold_usec, 1U, MEMORY_PRESSURE_DEFAULT_WINDOW_USEC), + MEMORY_PRESSURE_DEFAULT_WINDOW_USEC) < 0) + return -ENOMEM; + + if (base64mem(b, strlen(b) + 1, &e) < 0) + return -ENOMEM; + + x = strjoin("MEMORY_PRESSURE_WRITE=", e); + if (!x) + return -ENOMEM; + + our_env[n_env++] = x; + } + } + + assert(n_env < N_ENV_VARS + _EXEC_DIRECTORY_TYPE_MAX); +#undef N_ENV_VARS + + *ret = TAKE_PTR(our_env); + + return 0; +} + +static int build_pass_environment(const ExecContext *c, char ***ret) { + _cleanup_strv_free_ char **pass_env = NULL; + size_t n_env = 0; + + STRV_FOREACH(i, c->pass_environment) { + _cleanup_free_ char *x = NULL; + char *v; + + v = getenv(*i); + if (!v) + continue; + x = strjoin(*i, "=", v); + if (!x) + return -ENOMEM; + + if (!GREEDY_REALLOC(pass_env, n_env + 2)) + return -ENOMEM; + + pass_env[n_env++] = TAKE_PTR(x); + pass_env[n_env] = NULL; + } + + *ret = TAKE_PTR(pass_env); + + return 0; +} + +static int setup_private_users(uid_t ouid, gid_t ogid, uid_t uid, gid_t gid) { + _cleanup_free_ char *uid_map = NULL, *gid_map = NULL; + _cleanup_close_pair_ int errno_pipe[2] = EBADF_PAIR; + _cleanup_close_ int unshare_ready_fd = -EBADF; + _cleanup_(sigkill_waitp) pid_t pid = 0; + uint64_t c = 1; + ssize_t n; + int r; + + /* Set up a user namespace and map the original UID/GID (IDs from before any user or group changes, i.e. + * the IDs from the user or system manager(s)) to itself, the selected UID/GID to itself, and everything else to + * nobody. In order to be able to write this mapping we need CAP_SETUID in the original user namespace, which + * we however lack after opening the user namespace. To work around this we fork() a temporary child process, + * which waits for the parent to create the new user namespace while staying in the original namespace. The + * child then writes the UID mapping, under full privileges. The parent waits for the child to finish and + * continues execution normally. + * For unprivileged users (i.e. without capabilities), the root to root mapping is excluded. As such, it + * does not need CAP_SETUID to write the single line mapping to itself. */ + + /* Can only set up multiple mappings with CAP_SETUID. */ + if (have_effective_cap(CAP_SETUID) > 0 && uid != ouid && uid_is_valid(uid)) + r = asprintf(&uid_map, + UID_FMT " " UID_FMT " 1\n" /* Map $OUID → $OUID */ + UID_FMT " " UID_FMT " 1\n", /* Map $UID → $UID */ + ouid, ouid, uid, uid); + else + r = asprintf(&uid_map, + UID_FMT " " UID_FMT " 1\n", /* Map $OUID → $OUID */ + ouid, ouid); + + if (r < 0) + return -ENOMEM; + + /* Can only set up multiple mappings with CAP_SETGID. */ + if (have_effective_cap(CAP_SETGID) > 0 && gid != ogid && gid_is_valid(gid)) + r = asprintf(&gid_map, + GID_FMT " " GID_FMT " 1\n" /* Map $OGID → $OGID */ + GID_FMT " " GID_FMT " 1\n", /* Map $GID → $GID */ + ogid, ogid, gid, gid); + else + r = asprintf(&gid_map, + GID_FMT " " GID_FMT " 1\n", /* Map $OGID -> $OGID */ + ogid, ogid); + + if (r < 0) + return -ENOMEM; + + /* Create a communication channel so that the parent can tell the child when it finished creating the user + * namespace. */ + unshare_ready_fd = eventfd(0, EFD_CLOEXEC); + if (unshare_ready_fd < 0) + return -errno; + + /* Create a communication channel so that the child can tell the parent a proper error code in case it + * failed. */ + if (pipe2(errno_pipe, O_CLOEXEC) < 0) + return -errno; + + r = safe_fork("(sd-userns)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGKILL, &pid); + if (r < 0) + return r; + if (r == 0) { + _cleanup_close_ int fd = -EBADF; + const char *a; + pid_t ppid; + + /* Child process, running in the original user namespace. Let's update the parent's UID/GID map from + * here, after the parent opened its own user namespace. */ + + ppid = getppid(); + errno_pipe[0] = safe_close(errno_pipe[0]); + + /* Wait until the parent unshared the user namespace */ + if (read(unshare_ready_fd, &c, sizeof(c)) < 0) { + r = -errno; + goto child_fail; + } + + /* Disable the setgroups() system call in the child user namespace, for good. */ + a = procfs_file_alloca(ppid, "setgroups"); + fd = open(a, O_WRONLY|O_CLOEXEC); + if (fd < 0) { + if (errno != ENOENT) { + r = -errno; + goto child_fail; + } + + /* If the file is missing the kernel is too old, let's continue anyway. */ + } else { + if (write(fd, "deny\n", 5) < 0) { + r = -errno; + goto child_fail; + } + + fd = safe_close(fd); + } + + /* First write the GID map */ + a = procfs_file_alloca(ppid, "gid_map"); + fd = open(a, O_WRONLY|O_CLOEXEC); + if (fd < 0) { + r = -errno; + goto child_fail; + } + if (write(fd, gid_map, strlen(gid_map)) < 0) { + r = -errno; + goto child_fail; + } + fd = safe_close(fd); + + /* The write the UID map */ + a = procfs_file_alloca(ppid, "uid_map"); + fd = open(a, O_WRONLY|O_CLOEXEC); + if (fd < 0) { + r = -errno; + goto child_fail; + } + if (write(fd, uid_map, strlen(uid_map)) < 0) { + r = -errno; + goto child_fail; + } + + _exit(EXIT_SUCCESS); + + child_fail: + (void) write(errno_pipe[1], &r, sizeof(r)); + _exit(EXIT_FAILURE); + } + + errno_pipe[1] = safe_close(errno_pipe[1]); + + if (unshare(CLONE_NEWUSER) < 0) + return -errno; + + /* Let the child know that the namespace is ready now */ + if (write(unshare_ready_fd, &c, sizeof(c)) < 0) + return -errno; + + /* Try to read an error code from the child */ + n = read(errno_pipe[0], &r, sizeof(r)); + if (n < 0) + return -errno; + if (n == sizeof(r)) { /* an error code was sent to us */ + if (r < 0) + return r; + return -EIO; + } + if (n != 0) /* on success we should have read 0 bytes */ + return -EIO; + + r = wait_for_terminate_and_check("(sd-userns)", TAKE_PID(pid), 0); + if (r < 0) + return r; + if (r != EXIT_SUCCESS) /* If something strange happened with the child, let's consider this fatal, too */ + return -EIO; + + return 0; +} + +static int create_many_symlinks(const char *root, const char *source, char **symlinks) { + _cleanup_free_ char *src_abs = NULL; + int r; + + assert(source); + + src_abs = path_join(root, source); + if (!src_abs) + return -ENOMEM; + + STRV_FOREACH(dst, symlinks) { + _cleanup_free_ char *dst_abs = NULL; + + dst_abs = path_join(root, *dst); + if (!dst_abs) + return -ENOMEM; + + r = mkdir_parents_label(dst_abs, 0755); + if (r < 0) + return r; + + r = symlink_idempotent(src_abs, dst_abs, true); + if (r < 0) + return r; + } + + return 0; +} + +static int setup_exec_directory( + const ExecContext *context, + const ExecParameters *params, + uid_t uid, + gid_t gid, + ExecDirectoryType type, + bool needs_mount_namespace, + int *exit_status) { + + static const int exit_status_table[_EXEC_DIRECTORY_TYPE_MAX] = { + [EXEC_DIRECTORY_RUNTIME] = EXIT_RUNTIME_DIRECTORY, + [EXEC_DIRECTORY_STATE] = EXIT_STATE_DIRECTORY, + [EXEC_DIRECTORY_CACHE] = EXIT_CACHE_DIRECTORY, + [EXEC_DIRECTORY_LOGS] = EXIT_LOGS_DIRECTORY, + [EXEC_DIRECTORY_CONFIGURATION] = EXIT_CONFIGURATION_DIRECTORY, + }; + int r; + + assert(context); + assert(params); + assert(type >= 0 && type < _EXEC_DIRECTORY_TYPE_MAX); + assert(exit_status); + + if (!params->prefix[type]) + return 0; + + if (params->flags & EXEC_CHOWN_DIRECTORIES) { + if (!uid_is_valid(uid)) + uid = 0; + if (!gid_is_valid(gid)) + gid = 0; + } + + for (size_t i = 0; i < context->directories[type].n_items; i++) { + _cleanup_free_ char *p = NULL, *pp = NULL; + + p = path_join(params->prefix[type], context->directories[type].items[i].path); + if (!p) { + r = -ENOMEM; + goto fail; + } + + r = mkdir_parents_label(p, 0755); + if (r < 0) + goto fail; + + if (IN_SET(type, EXEC_DIRECTORY_STATE, EXEC_DIRECTORY_LOGS) && params->runtime_scope == RUNTIME_SCOPE_USER) { + + /* If we are in user mode, and a configuration directory exists but a state directory + * doesn't exist, then we likely are upgrading from an older systemd version that + * didn't know the more recent addition to the xdg-basedir spec: the $XDG_STATE_HOME + * directory. In older systemd versions EXEC_DIRECTORY_STATE was aliased to + * EXEC_DIRECTORY_CONFIGURATION, with the advent of $XDG_STATE_HOME is is now + * separated. If a service has both dirs configured but only the configuration dir + * exists and the state dir does not, we assume we are looking at an update + * situation. Hence, create a compatibility symlink, so that all expectations are + * met. + * + * (We also do something similar with the log directory, which still doesn't exist in + * the xdg basedir spec. We'll make it a subdir of the state dir.) */ + + /* this assumes the state dir is always created before the configuration dir */ + assert_cc(EXEC_DIRECTORY_STATE < EXEC_DIRECTORY_LOGS); + assert_cc(EXEC_DIRECTORY_LOGS < EXEC_DIRECTORY_CONFIGURATION); + + r = laccess(p, F_OK); + if (r == -ENOENT) { + _cleanup_free_ char *q = NULL; + + /* OK, we know that the state dir does not exist. Let's see if the dir exists + * under the configuration hierarchy. */ + + if (type == EXEC_DIRECTORY_STATE) + q = path_join(params->prefix[EXEC_DIRECTORY_CONFIGURATION], context->directories[type].items[i].path); + else if (type == EXEC_DIRECTORY_LOGS) + q = path_join(params->prefix[EXEC_DIRECTORY_CONFIGURATION], "log", context->directories[type].items[i].path); + else + assert_not_reached(); + if (!q) { + r = -ENOMEM; + goto fail; + } + + r = laccess(q, F_OK); + if (r >= 0) { + /* It does exist! This hence looks like an update. Symlink the + * configuration directory into the state directory. */ + + r = symlink_idempotent(q, p, /* make_relative= */ true); + if (r < 0) + goto fail; + + log_exec_notice(context, params, "Unit state directory %s missing but matching configuration directory %s exists, assuming update from systemd 253 or older, creating compatibility symlink.", p, q); + continue; + } else if (r != -ENOENT) + log_exec_warning_errno(context, params, r, "Unable to detect whether unit configuration directory '%s' exists, assuming not: %m", q); + + } else if (r < 0) + log_exec_warning_errno(context, params, r, "Unable to detect whether unit state directory '%s' is missing, assuming it is: %m", p); + } + + if (exec_directory_is_private(context, type)) { + /* So, here's one extra complication when dealing with DynamicUser=1 units. In that + * case we want to avoid leaving a directory around fully accessible that is owned by + * a dynamic user whose UID is later on reused. To lock this down we use the same + * trick used by container managers to prohibit host users to get access to files of + * the same UID in containers: we place everything inside a directory that has an + * access mode of 0700 and is owned root:root, so that it acts as security boundary + * for unprivileged host code. We then use fs namespacing to make this directory + * permeable for the service itself. + * + * Specifically: for a service which wants a special directory "foo/" we first create + * a directory "private/" with access mode 0700 owned by root:root. Then we place + * "foo" inside of that directory (i.e. "private/foo/"), and make "foo" a symlink to + * "private/foo". This way, privileged host users can access "foo/" as usual, but + * unprivileged host users can't look into it. Inside of the namespace of the unit + * "private/" is replaced by a more liberally accessible tmpfs, into which the host's + * "private/foo/" is mounted under the same name, thus disabling the access boundary + * for the service and making sure it only gets access to the dirs it needs but no + * others. Tricky? Yes, absolutely, but it works! + * + * Note that we don't do this for EXEC_DIRECTORY_CONFIGURATION as that's assumed not + * to be owned by the service itself. + * + * Also, note that we don't do this for EXEC_DIRECTORY_RUNTIME as that's often used + * for sharing files or sockets with other services. */ + + pp = path_join(params->prefix[type], "private"); + if (!pp) { + r = -ENOMEM; + goto fail; + } + + /* First set up private root if it doesn't exist yet, with access mode 0700 and owned by root:root */ + r = mkdir_safe_label(pp, 0700, 0, 0, MKDIR_WARN_MODE); + if (r < 0) + goto fail; + + if (!path_extend(&pp, context->directories[type].items[i].path)) { + r = -ENOMEM; + goto fail; + } + + /* Create all directories between the configured directory and this private root, and mark them 0755 */ + r = mkdir_parents_label(pp, 0755); + if (r < 0) + goto fail; + + if (is_dir(p, false) > 0 && + (laccess(pp, F_OK) == -ENOENT)) { + + /* Hmm, the private directory doesn't exist yet, but the normal one exists? If so, move + * it over. Most likely the service has been upgraded from one that didn't use + * DynamicUser=1, to one that does. */ + + log_exec_info(context, + params, + "Found pre-existing public %s= directory %s, migrating to %s.\n" + "Apparently, service previously had DynamicUser= turned off, and has now turned it on.", + exec_directory_type_to_string(type), p, pp); + + r = RET_NERRNO(rename(p, pp)); + if (r < 0) + goto fail; + } else { + /* Otherwise, create the actual directory for the service */ + + r = mkdir_label(pp, context->directories[type].mode); + if (r < 0 && r != -EEXIST) + goto fail; + } + + if (!context->directories[type].items[i].only_create) { + /* And link it up from the original place. + * Notes + * 1) If a mount namespace is going to be used, then this symlink remains on + * the host, and a new one for the child namespace will be created later. + * 2) It is not necessary to create this symlink when one of its parent + * directories is specified and already created. E.g. + * StateDirectory=foo foo/bar + * In that case, the inode points to pp and p for "foo/bar" are the same: + * pp = "/var/lib/private/foo/bar" + * p = "/var/lib/foo/bar" + * and, /var/lib/foo is a symlink to /var/lib/private/foo. So, not only + * we do not need to create the symlink, but we cannot create the symlink. + * See issue #24783. */ + r = symlink_idempotent(pp, p, true); + if (r < 0) + goto fail; + } + + } else { + _cleanup_free_ char *target = NULL; + + if (type != EXEC_DIRECTORY_CONFIGURATION && + readlink_and_make_absolute(p, &target) >= 0) { + _cleanup_free_ char *q = NULL, *q_resolved = NULL, *target_resolved = NULL; + + /* This already exists and is a symlink? Interesting. Maybe it's one created + * by DynamicUser=1 (see above)? + * + * We do this for all directory types except for ConfigurationDirectory=, + * since they all support the private/ symlink logic at least in some + * configurations, see above. */ + + r = chase(target, NULL, 0, &target_resolved, NULL); + if (r < 0) + goto fail; + + q = path_join(params->prefix[type], "private", context->directories[type].items[i].path); + if (!q) { + r = -ENOMEM; + goto fail; + } + + /* /var/lib or friends may be symlinks. So, let's chase them also. */ + r = chase(q, NULL, CHASE_NONEXISTENT, &q_resolved, NULL); + if (r < 0) + goto fail; + + if (path_equal(q_resolved, target_resolved)) { + + /* Hmm, apparently DynamicUser= was once turned on for this service, + * but is no longer. Let's move the directory back up. */ + + log_exec_info(context, + params, + "Found pre-existing private %s= directory %s, migrating to %s.\n" + "Apparently, service previously had DynamicUser= turned on, and has now turned it off.", + exec_directory_type_to_string(type), q, p); + + r = RET_NERRNO(unlink(p)); + if (r < 0) + goto fail; + + r = RET_NERRNO(rename(q, p)); + if (r < 0) + goto fail; + } + } + + r = mkdir_label(p, context->directories[type].mode); + if (r < 0) { + if (r != -EEXIST) + goto fail; + + if (type == EXEC_DIRECTORY_CONFIGURATION) { + struct stat st; + + /* Don't change the owner/access mode of the configuration directory, + * as in the common case it is not written to by a service, and shall + * not be writable. */ + + r = RET_NERRNO(stat(p, &st)); + if (r < 0) + goto fail; + + /* Still complain if the access mode doesn't match */ + if (((st.st_mode ^ context->directories[type].mode) & 07777) != 0) + log_exec_warning(context, + params, + "%s \'%s\' already exists but the mode is different. " + "(File system: %o %sMode: %o)", + exec_directory_type_to_string(type), context->directories[type].items[i].path, + st.st_mode & 07777, exec_directory_type_to_string(type), context->directories[type].mode & 07777); + + continue; + } + } + } + + /* Lock down the access mode (we use chmod_and_chown() to make this idempotent. We don't + * specify UID/GID here, so that path_chown_recursive() can optimize things depending on the + * current UID/GID ownership.) */ + r = chmod_and_chown(pp ?: p, context->directories[type].mode, UID_INVALID, GID_INVALID); + if (r < 0) + goto fail; + + /* Skip the rest (which deals with ownership) in user mode, since ownership changes are not + * available to user code anyway */ + if (params->runtime_scope != RUNTIME_SCOPE_SYSTEM) + continue; + + /* Then, change the ownership of the whole tree, if necessary. When dynamic users are used we + * drop the suid/sgid bits, since we really don't want SUID/SGID files for dynamic UID/GID + * assignments to exist. */ + r = path_chown_recursive(pp ?: p, uid, gid, context->dynamic_user ? 01777 : 07777, AT_SYMLINK_FOLLOW); + if (r < 0) + goto fail; + } + + /* If we are not going to run in a namespace, set up the symlinks - otherwise + * they are set up later, to allow configuring empty var/run/etc. */ + if (!needs_mount_namespace) + for (size_t i = 0; i < context->directories[type].n_items; i++) { + r = create_many_symlinks(params->prefix[type], + context->directories[type].items[i].path, + context->directories[type].items[i].symlinks); + if (r < 0) + goto fail; + } + + return 0; + +fail: + *exit_status = exit_status_table[type]; + return r; +} + +#if ENABLE_SMACK +static int setup_smack( + const ExecParameters *params, + const ExecContext *context, + int executable_fd) { + int r; + + assert(params); + assert(executable_fd >= 0); + + if (context->smack_process_label) { + r = mac_smack_apply_pid(0, context->smack_process_label); + if (r < 0) + return r; + } else if (params->fallback_smack_process_label) { + _cleanup_free_ char *exec_label = NULL; + + r = mac_smack_read_fd(executable_fd, SMACK_ATTR_EXEC, &exec_label); + if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r)) + return r; + + r = mac_smack_apply_pid(0, exec_label ?: params->fallback_smack_process_label); + if (r < 0) + return r; + } + + return 0; +} +#endif + +static int compile_bind_mounts( + const ExecContext *context, + const ExecParameters *params, + BindMount **ret_bind_mounts, + size_t *ret_n_bind_mounts, + char ***ret_empty_directories) { + + _cleanup_strv_free_ char **empty_directories = NULL; + BindMount *bind_mounts = NULL; + size_t n, h = 0; + int r; + + assert(context); + assert(params); + assert(ret_bind_mounts); + assert(ret_n_bind_mounts); + assert(ret_empty_directories); + + CLEANUP_ARRAY(bind_mounts, h, bind_mount_free_many); + + n = context->n_bind_mounts; + for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) { + if (!params->prefix[t]) + continue; + + for (size_t i = 0; i < context->directories[t].n_items; i++) + n += !context->directories[t].items[i].only_create; + } + + if (n <= 0) { + *ret_bind_mounts = NULL; + *ret_n_bind_mounts = 0; + *ret_empty_directories = NULL; + return 0; + } + + bind_mounts = new(BindMount, n); + if (!bind_mounts) + return -ENOMEM; + + for (size_t i = 0; i < context->n_bind_mounts; i++) { + BindMount *item = context->bind_mounts + i; + _cleanup_free_ char *s = NULL, *d = NULL; + + s = strdup(item->source); + if (!s) + return -ENOMEM; + + d = strdup(item->destination); + if (!d) + return -ENOMEM; + + bind_mounts[h++] = (BindMount) { + .source = TAKE_PTR(s), + .destination = TAKE_PTR(d), + .read_only = item->read_only, + .recursive = item->recursive, + .ignore_enoent = item->ignore_enoent, + }; + } + + for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) { + if (!params->prefix[t]) + continue; + + if (context->directories[t].n_items == 0) + continue; + + if (exec_directory_is_private(context, t) && + !exec_context_with_rootfs(context)) { + char *private_root; + + /* So this is for a dynamic user, and we need to make sure the process can access its own + * directory. For that we overmount the usually inaccessible "private" subdirectory with a + * tmpfs that makes it accessible and is empty except for the submounts we do this for. */ + + private_root = path_join(params->prefix[t], "private"); + if (!private_root) + return -ENOMEM; + + r = strv_consume(&empty_directories, private_root); + if (r < 0) + return r; + } + + for (size_t i = 0; i < context->directories[t].n_items; i++) { + _cleanup_free_ char *s = NULL, *d = NULL; + + /* When one of the parent directories is in the list, we cannot create the symlink + * for the child directory. See also the comments in setup_exec_directory(). */ + if (context->directories[t].items[i].only_create) + continue; + + if (exec_directory_is_private(context, t)) + s = path_join(params->prefix[t], "private", context->directories[t].items[i].path); + else + s = path_join(params->prefix[t], context->directories[t].items[i].path); + if (!s) + return -ENOMEM; + + if (exec_directory_is_private(context, t) && + exec_context_with_rootfs(context)) + /* When RootDirectory= or RootImage= are set, then the symbolic link to the private + * directory is not created on the root directory. So, let's bind-mount the directory + * on the 'non-private' place. */ + d = path_join(params->prefix[t], context->directories[t].items[i].path); + else + d = strdup(s); + if (!d) + return -ENOMEM; + + bind_mounts[h++] = (BindMount) { + .source = TAKE_PTR(s), + .destination = TAKE_PTR(d), + .read_only = false, + .nosuid = context->dynamic_user, /* don't allow suid/sgid when DynamicUser= is on */ + .recursive = true, + .ignore_enoent = false, + }; + } + } + + assert(h == n); + + *ret_bind_mounts = TAKE_PTR(bind_mounts); + *ret_n_bind_mounts = n; + *ret_empty_directories = TAKE_PTR(empty_directories); + + return (int) n; +} + +/* ret_symlinks will contain a list of pairs src:dest that describes + * the symlinks to create later on. For example, the symlinks needed + * to safely give private directories to DynamicUser=1 users. */ +static int compile_symlinks( + const ExecContext *context, + const ExecParameters *params, + bool setup_os_release_symlink, + char ***ret_symlinks) { + + _cleanup_strv_free_ char **symlinks = NULL; + int r; + + assert(context); + assert(params); + assert(ret_symlinks); + + for (ExecDirectoryType dt = 0; dt < _EXEC_DIRECTORY_TYPE_MAX; dt++) { + for (size_t i = 0; i < context->directories[dt].n_items; i++) { + _cleanup_free_ char *private_path = NULL, *path = NULL; + + STRV_FOREACH(symlink, context->directories[dt].items[i].symlinks) { + _cleanup_free_ char *src_abs = NULL, *dst_abs = NULL; + + src_abs = path_join(params->prefix[dt], context->directories[dt].items[i].path); + dst_abs = path_join(params->prefix[dt], *symlink); + if (!src_abs || !dst_abs) + return -ENOMEM; + + r = strv_consume_pair(&symlinks, TAKE_PTR(src_abs), TAKE_PTR(dst_abs)); + if (r < 0) + return r; + } + + if (!exec_directory_is_private(context, dt) || + exec_context_with_rootfs(context) || + context->directories[dt].items[i].only_create) + continue; + + private_path = path_join(params->prefix[dt], "private", context->directories[dt].items[i].path); + if (!private_path) + return -ENOMEM; + + path = path_join(params->prefix[dt], context->directories[dt].items[i].path); + if (!path) + return -ENOMEM; + + r = strv_consume_pair(&symlinks, TAKE_PTR(private_path), TAKE_PTR(path)); + if (r < 0) + return r; + } + } + + /* We make the host's os-release available via a symlink, so that we can copy it atomically + * and readers will never get a half-written version. Note that, while the paths specified here are + * absolute, when they are processed in namespace.c they will be made relative automatically, i.e.: + * 'os-release -> .os-release-stage/os-release' is what will be created. */ + if (setup_os_release_symlink) { + r = strv_extend(&symlinks, "/run/host/.os-release-stage/os-release"); + if (r < 0) + return r; + + r = strv_extend(&symlinks, "/run/host/os-release"); + if (r < 0) + return r; + } + + *ret_symlinks = TAKE_PTR(symlinks); + + return 0; +} + +static bool insist_on_sandboxing( + const ExecContext *context, + const char *root_dir, + const char *root_image, + const BindMount *bind_mounts, + size_t n_bind_mounts) { + + assert(context); + assert(n_bind_mounts == 0 || bind_mounts); + + /* Checks whether we need to insist on fs namespacing. i.e. whether we have settings configured that + * would alter the view on the file system beyond making things read-only or invisible, i.e. would + * rearrange stuff in a way we cannot ignore gracefully. */ + + if (context->n_temporary_filesystems > 0) + return true; + + if (root_dir || root_image) + return true; + + if (context->n_mount_images > 0) + return true; + + if (context->dynamic_user) + return true; + + if (context->n_extension_images > 0 || !strv_isempty(context->extension_directories)) + return true; + + /* If there are any bind mounts set that don't map back onto themselves, fs namespacing becomes + * essential. */ + for (size_t i = 0; i < n_bind_mounts; i++) + if (!path_equal(bind_mounts[i].source, bind_mounts[i].destination)) + return true; + + if (context->log_namespace) + return true; + + return false; +} + +static int setup_ephemeral(const ExecContext *context, ExecRuntime *runtime) { + _cleanup_close_ int fd = -EBADF; + int r; + + if (!runtime || !runtime->ephemeral_copy) + return 0; + + r = posix_lock(runtime->ephemeral_storage_socket[0], LOCK_EX); + if (r < 0) + return log_debug_errno(r, "Failed to lock ephemeral storage socket: %m"); + + CLEANUP_POSIX_UNLOCK(runtime->ephemeral_storage_socket[0]); + + fd = receive_one_fd(runtime->ephemeral_storage_socket[0], MSG_PEEK|MSG_DONTWAIT); + if (fd >= 0) + /* We got an fd! That means ephemeral has already been set up, so nothing to do here. */ + return 0; + + if (fd != -EAGAIN) + return log_debug_errno(fd, "Failed to receive file descriptor queued on ephemeral storage socket: %m"); + + log_debug("Making ephemeral snapshot of %s to %s", + context->root_image ?: context->root_directory, runtime->ephemeral_copy); + + if (context->root_image) + fd = copy_file(context->root_image, runtime->ephemeral_copy, O_EXCL, 0600, + COPY_LOCK_BSD|COPY_REFLINK|COPY_CRTIME); + else + fd = btrfs_subvol_snapshot_at(AT_FDCWD, context->root_directory, + AT_FDCWD, runtime->ephemeral_copy, + BTRFS_SNAPSHOT_FALLBACK_COPY | + BTRFS_SNAPSHOT_FALLBACK_DIRECTORY | + BTRFS_SNAPSHOT_RECURSIVE | + BTRFS_SNAPSHOT_LOCK_BSD); + if (fd < 0) + return log_debug_errno(fd, "Failed to snapshot %s to %s: %m", + context->root_image ?: context->root_directory, runtime->ephemeral_copy); + + if (context->root_image) { + /* A root image might be subject to lots of random writes so let's try to disable COW on it + * which tends to not perform well in combination with lots of random writes. + * + * Note: btrfs actually isn't impressed by us setting the flag after making the reflink'ed + * copy, but we at least want to make the intention clear. + */ + r = chattr_fd(fd, FS_NOCOW_FL, FS_NOCOW_FL, NULL); + if (r < 0) + log_debug_errno(fd, "Failed to disable copy-on-write for %s, ignoring: %m", runtime->ephemeral_copy); + } + + r = send_one_fd(runtime->ephemeral_storage_socket[1], fd, MSG_DONTWAIT); + if (r < 0) + return log_debug_errno(r, "Failed to queue file descriptor on ephemeral storage socket: %m"); + + return 1; +} + +static int verity_settings_prepare( + VeritySettings *verity, + const char *root_image, + const void *root_hash, + size_t root_hash_size, + const char *root_hash_path, + const void *root_hash_sig, + size_t root_hash_sig_size, + const char *root_hash_sig_path, + const char *verity_data_path) { + + int r; + + assert(verity); + + if (root_hash) { + void *d; + + d = memdup(root_hash, root_hash_size); + if (!d) + return -ENOMEM; + + free_and_replace(verity->root_hash, d); + verity->root_hash_size = root_hash_size; + verity->designator = PARTITION_ROOT; + } + + if (root_hash_sig) { + void *d; + + d = memdup(root_hash_sig, root_hash_sig_size); + if (!d) + return -ENOMEM; + + free_and_replace(verity->root_hash_sig, d); + verity->root_hash_sig_size = root_hash_sig_size; + verity->designator = PARTITION_ROOT; + } + + if (verity_data_path) { + r = free_and_strdup(&verity->data_path, verity_data_path); + if (r < 0) + return r; + } + + r = verity_settings_load( + verity, + root_image, + root_hash_path, + root_hash_sig_path); + if (r < 0) + return log_debug_errno(r, "Failed to load root hash: %m"); + + return 0; +} + +static int apply_mount_namespace( + ExecCommandFlags command_flags, + const ExecContext *context, + const ExecParameters *params, + ExecRuntime *runtime, + const char *memory_pressure_path, + char **error_path) { + + _cleanup_(verity_settings_done) VeritySettings verity = VERITY_SETTINGS_DEFAULT; + _cleanup_strv_free_ char **empty_directories = NULL, **symlinks = NULL, + **read_write_paths_cleanup = NULL; + _cleanup_free_ char *creds_path = NULL, *incoming_dir = NULL, *propagate_dir = NULL, + *extension_dir = NULL, *host_os_release_stage = NULL; + const char *root_dir = NULL, *root_image = NULL, *tmp_dir = NULL, *var_tmp_dir = NULL; + char **read_write_paths; + bool needs_sandboxing, setup_os_release_symlink; + BindMount *bind_mounts = NULL; + size_t n_bind_mounts = 0; + int r; + + assert(context); + + CLEANUP_ARRAY(bind_mounts, n_bind_mounts, bind_mount_free_many); + + if (params->flags & EXEC_APPLY_CHROOT) { + r = setup_ephemeral(context, runtime); + if (r < 0) + return r; + + if (context->root_image) + root_image = (runtime ? runtime->ephemeral_copy : NULL) ?: context->root_image; + else + root_dir = (runtime ? runtime->ephemeral_copy : NULL) ?: context->root_directory; + } + + r = compile_bind_mounts(context, params, &bind_mounts, &n_bind_mounts, &empty_directories); + if (r < 0) + return r; + + /* We need to make the pressure path writable even if /sys/fs/cgroups is made read-only, as the + * service will need to write to it in order to start the notifications. */ + if (context->protect_control_groups && memory_pressure_path && !streq(memory_pressure_path, "/dev/null")) { + read_write_paths_cleanup = strv_copy(context->read_write_paths); + if (!read_write_paths_cleanup) + return -ENOMEM; + + r = strv_extend(&read_write_paths_cleanup, memory_pressure_path); + if (r < 0) + return r; + + read_write_paths = read_write_paths_cleanup; + } else + read_write_paths = context->read_write_paths; + + needs_sandboxing = (params->flags & EXEC_APPLY_SANDBOXING) && !(command_flags & EXEC_COMMAND_FULLY_PRIVILEGED); + if (needs_sandboxing) { + /* The runtime struct only contains the parent of the private /tmp, which is non-accessible + * to world users. Inside of it there's a /tmp that is sticky, and that's the one we want to + * use here. This does not apply when we are using /run/systemd/empty as fallback. */ + + if (context->private_tmp && runtime && runtime->shared) { + if (streq_ptr(runtime->shared->tmp_dir, RUN_SYSTEMD_EMPTY)) + tmp_dir = runtime->shared->tmp_dir; + else if (runtime->shared->tmp_dir) + tmp_dir = strjoina(runtime->shared->tmp_dir, "/tmp"); + + if (streq_ptr(runtime->shared->var_tmp_dir, RUN_SYSTEMD_EMPTY)) + var_tmp_dir = runtime->shared->var_tmp_dir; + else if (runtime->shared->var_tmp_dir) + var_tmp_dir = strjoina(runtime->shared->var_tmp_dir, "/tmp"); + } + } + + /* Symlinks (exec dirs, os-release) are set up after other mounts, before they are made read-only. */ + setup_os_release_symlink = needs_sandboxing && exec_context_get_effective_mount_apivfs(context) && (root_dir || root_image); + r = compile_symlinks(context, params, setup_os_release_symlink, &symlinks); + if (r < 0) + return r; + + if (context->mount_propagation_flag == MS_SHARED) + log_exec_debug(context, + params, + "shared mount propagation hidden by other fs namespacing unit settings: ignoring"); + + if (FLAGS_SET(params->flags, EXEC_WRITE_CREDENTIALS)) { + r = exec_context_get_credential_directory(context, params, params->unit_id, &creds_path); + if (r < 0) + return r; + } + + if (params->runtime_scope == RUNTIME_SCOPE_SYSTEM) { + propagate_dir = path_join("/run/systemd/propagate/", params->unit_id); + if (!propagate_dir) + return -ENOMEM; + + incoming_dir = strdup("/run/systemd/incoming"); + if (!incoming_dir) + return -ENOMEM; + + extension_dir = strdup("/run/systemd/unit-extensions"); + if (!extension_dir) + return -ENOMEM; + + /* If running under a different root filesystem, propagate the host's os-release. We make a + * copy rather than just bind mounting it, so that it can be updated on soft-reboot. */ + if (setup_os_release_symlink) { + host_os_release_stage = strdup("/run/systemd/propagate/.os-release-stage"); + if (!host_os_release_stage) + return -ENOMEM; + } + } else { + assert(params->runtime_scope == RUNTIME_SCOPE_USER); + + if (asprintf(&extension_dir, "/run/user/" UID_FMT "/systemd/unit-extensions", geteuid()) < 0) + return -ENOMEM; + + if (setup_os_release_symlink) { + if (asprintf(&host_os_release_stage, + "/run/user/" UID_FMT "/systemd/propagate/.os-release-stage", + geteuid()) < 0) + return -ENOMEM; + } + } + + if (root_image) { + r = verity_settings_prepare( + &verity, + root_image, + context->root_hash, context->root_hash_size, context->root_hash_path, + context->root_hash_sig, context->root_hash_sig_size, context->root_hash_sig_path, + context->root_verity); + if (r < 0) + return r; + } + + NamespaceParameters parameters = { + .runtime_scope = params->runtime_scope, + + .root_directory = root_dir, + .root_image = root_image, + .root_image_options = context->root_image_options, + .root_image_policy = context->root_image_policy ?: &image_policy_service, + + .read_write_paths = read_write_paths, + .read_only_paths = needs_sandboxing ? context->read_only_paths : NULL, + .inaccessible_paths = needs_sandboxing ? context->inaccessible_paths : NULL, + + .exec_paths = needs_sandboxing ? context->exec_paths : NULL, + .no_exec_paths = needs_sandboxing ? context->no_exec_paths : NULL, + + .empty_directories = empty_directories, + .symlinks = symlinks, + + .bind_mounts = bind_mounts, + .n_bind_mounts = n_bind_mounts, + + .temporary_filesystems = context->temporary_filesystems, + .n_temporary_filesystems = context->n_temporary_filesystems, + + .mount_images = context->mount_images, + .n_mount_images = context->n_mount_images, + .mount_image_policy = context->mount_image_policy ?: &image_policy_service, + + .tmp_dir = tmp_dir, + .var_tmp_dir = var_tmp_dir, + + .creds_path = creds_path, + .log_namespace = context->log_namespace, + .mount_propagation_flag = context->mount_propagation_flag, + + .verity = &verity, + + .extension_images = context->extension_images, + .n_extension_images = context->n_extension_images, + .extension_image_policy = context->extension_image_policy ?: &image_policy_sysext, + .extension_directories = context->extension_directories, + + .propagate_dir = propagate_dir, + .incoming_dir = incoming_dir, + .extension_dir = extension_dir, + .notify_socket = root_dir || root_image ? params->notify_socket : NULL, + .host_os_release_stage = host_os_release_stage, + + /* If DynamicUser=no and RootDirectory= is set then lets pass a relaxed sandbox info, + * otherwise enforce it, don't ignore protected paths and fail if we are enable to apply the + * sandbox inside the mount namespace. */ + .ignore_protect_paths = !needs_sandboxing && !context->dynamic_user && root_dir, + + .protect_control_groups = needs_sandboxing && context->protect_control_groups, + .protect_kernel_tunables = needs_sandboxing && context->protect_kernel_tunables, + .protect_kernel_modules = needs_sandboxing && context->protect_kernel_modules, + .protect_kernel_logs = needs_sandboxing && context->protect_kernel_logs, + .protect_hostname = needs_sandboxing && context->protect_hostname, + + .private_dev = needs_sandboxing && context->private_devices, + .private_network = needs_sandboxing && exec_needs_network_namespace(context), + .private_ipc = needs_sandboxing && exec_needs_ipc_namespace(context), + + .mount_apivfs = needs_sandboxing && exec_context_get_effective_mount_apivfs(context), + + /* If NNP is on, we can turn on MS_NOSUID, since it won't have any effect anymore. */ + .mount_nosuid = needs_sandboxing && context->no_new_privileges && !mac_selinux_use(), + + .protect_home = needs_sandboxing ? context->protect_home : false, + .protect_system = needs_sandboxing ? context->protect_system : false, + .protect_proc = needs_sandboxing ? context->protect_proc : false, + .proc_subset = needs_sandboxing ? context->proc_subset : false, + }; + + r = setup_namespace(¶meters, error_path); + /* If we couldn't set up the namespace this is probably due to a missing capability. setup_namespace() reports + * that with a special, recognizable error ENOANO. In this case, silently proceed, but only if exclusively + * sandboxing options were used, i.e. nothing such as RootDirectory= or BindMount= that would result in a + * completely different execution environment. */ + if (r == -ENOANO) { + if (insist_on_sandboxing( + context, + root_dir, root_image, + bind_mounts, + n_bind_mounts)) + return log_exec_debug_errno(context, + params, + SYNTHETIC_ERRNO(EOPNOTSUPP), + "Failed to set up namespace, and refusing to continue since " + "the selected namespacing options alter mount environment non-trivially.\n" + "Bind mounts: %zu, temporary filesystems: %zu, root directory: %s, root image: %s, dynamic user: %s", + n_bind_mounts, + context->n_temporary_filesystems, + yes_no(root_dir), + yes_no(root_image), + yes_no(context->dynamic_user)); + + log_exec_debug(context, params, "Failed to set up namespace, assuming containerized execution and ignoring."); + return 0; + } + + return r; +} + +static int apply_working_directory( + const ExecContext *context, + const ExecParameters *params, + ExecRuntime *runtime, + const char *home, + int *exit_status) { + + const char *d, *wd; + + assert(context); + assert(exit_status); + + if (context->working_directory_home) { + + if (!home) { + *exit_status = EXIT_CHDIR; + return -ENXIO; + } + + wd = home; + + } else + wd = empty_to_root(context->working_directory); + + if (params->flags & EXEC_APPLY_CHROOT) + d = wd; + else + d = prefix_roota((runtime ? runtime->ephemeral_copy : NULL) ?: context->root_directory, wd); + + if (chdir(d) < 0 && !context->working_directory_missing_ok) { + *exit_status = EXIT_CHDIR; + return -errno; + } + + return 0; +} + +static int apply_root_directory( + const ExecContext *context, + const ExecParameters *params, + ExecRuntime *runtime, + const bool needs_mount_ns, + int *exit_status) { + + assert(context); + assert(exit_status); + + if (params->flags & EXEC_APPLY_CHROOT) + if (!needs_mount_ns && context->root_directory) + if (chroot((runtime ? runtime->ephemeral_copy : NULL) ?: context->root_directory) < 0) { + *exit_status = EXIT_CHROOT; + return -errno; + } + + return 0; +} + +static int setup_keyring( + const ExecContext *context, + const ExecParameters *p, + uid_t uid, gid_t gid) { + + key_serial_t keyring; + int r = 0; + uid_t saved_uid; + gid_t saved_gid; + + assert(context); + assert(p); + + /* Let's set up a new per-service "session" kernel keyring for each system service. This has the benefit that + * each service runs with its own keyring shared among all processes of the service, but with no hook-up beyond + * that scope, and in particular no link to the per-UID keyring. If we don't do this the keyring will be + * automatically created on-demand and then linked to the per-UID keyring, by the kernel. The kernel's built-in + * on-demand behaviour is very appropriate for login users, but probably not so much for system services, where + * UIDs are not necessarily specific to a service but reused (at least in the case of UID 0). */ + + if (context->keyring_mode == EXEC_KEYRING_INHERIT) + return 0; + + /* Acquiring a reference to the user keyring is nasty. We briefly change identity in order to get things set up + * properly by the kernel. If we don't do that then we can't create it atomically, and that sucks for parallel + * execution. This mimics what pam_keyinit does, too. Setting up session keyring, to be owned by the right user + * & group is just as nasty as acquiring a reference to the user keyring. */ + + saved_uid = getuid(); + saved_gid = getgid(); + + if (gid_is_valid(gid) && gid != saved_gid) { + if (setregid(gid, -1) < 0) + return log_exec_error_errno(context, + p, + errno, + "Failed to change GID for user keyring: %m"); + } + + if (uid_is_valid(uid) && uid != saved_uid) { + if (setreuid(uid, -1) < 0) { + r = log_exec_error_errno(context, + p, + errno, + "Failed to change UID for user keyring: %m"); + goto out; + } + } + + keyring = keyctl(KEYCTL_JOIN_SESSION_KEYRING, 0, 0, 0, 0); + if (keyring == -1) { + if (errno == ENOSYS) + log_exec_debug_errno(context, + p, + errno, + "Kernel keyring not supported, ignoring."); + else if (ERRNO_IS_PRIVILEGE(errno)) + log_exec_debug_errno(context, + p, + errno, + "Kernel keyring access prohibited, ignoring."); + else if (errno == EDQUOT) + log_exec_debug_errno(context, + p, + errno, + "Out of kernel keyrings to allocate, ignoring."); + else + r = log_exec_error_errno(context, + p, + errno, + "Setting up kernel keyring failed: %m"); + + goto out; + } + + /* When requested link the user keyring into the session keyring. */ + if (context->keyring_mode == EXEC_KEYRING_SHARED) { + + if (keyctl(KEYCTL_LINK, + KEY_SPEC_USER_KEYRING, + KEY_SPEC_SESSION_KEYRING, 0, 0) < 0) { + r = log_exec_error_errno(context, + p, + errno, + "Failed to link user keyring into session keyring: %m"); + goto out; + } + } + + /* Restore uid/gid back */ + if (uid_is_valid(uid) && uid != saved_uid) { + if (setreuid(saved_uid, -1) < 0) { + r = log_exec_error_errno(context, + p, + errno, + "Failed to change UID back for user keyring: %m"); + goto out; + } + } + + if (gid_is_valid(gid) && gid != saved_gid) { + if (setregid(saved_gid, -1) < 0) + return log_exec_error_errno(context, + p, + errno, + "Failed to change GID back for user keyring: %m"); + } + + /* Populate they keyring with the invocation ID by default, as original saved_uid. */ + if (!sd_id128_is_null(p->invocation_id)) { + key_serial_t key; + + key = add_key("user", + "invocation_id", + &p->invocation_id, + sizeof(p->invocation_id), + KEY_SPEC_SESSION_KEYRING); + if (key == -1) + log_exec_debug_errno(context, + p, + errno, + "Failed to add invocation ID to keyring, ignoring: %m"); + else { + if (keyctl(KEYCTL_SETPERM, key, + KEY_POS_VIEW|KEY_POS_READ|KEY_POS_SEARCH| + KEY_USR_VIEW|KEY_USR_READ|KEY_USR_SEARCH, 0, 0) < 0) + r = log_exec_error_errno(context, + p, + errno, + "Failed to restrict invocation ID permission: %m"); + } + } + +out: + /* Revert back uid & gid for the last time, and exit */ + /* no extra logging, as only the first already reported error matters */ + if (getuid() != saved_uid) + (void) setreuid(saved_uid, -1); + + if (getgid() != saved_gid) + (void) setregid(saved_gid, -1); + + return r; +} + +static void append_socket_pair(int *array, size_t *n, const int pair[static 2]) { + assert(array); + assert(n); + assert(pair); + + if (pair[0] >= 0) + array[(*n)++] = pair[0]; + if (pair[1] >= 0) + array[(*n)++] = pair[1]; +} + +static int close_remaining_fds( + const ExecParameters *params, + const ExecRuntime *runtime, + int socket_fd, + const int *fds, size_t n_fds) { + + size_t n_dont_close = 0; + int dont_close[n_fds + 14]; + + assert(params); + + if (params->stdin_fd >= 0) + dont_close[n_dont_close++] = params->stdin_fd; + if (params->stdout_fd >= 0) + dont_close[n_dont_close++] = params->stdout_fd; + if (params->stderr_fd >= 0) + dont_close[n_dont_close++] = params->stderr_fd; + + if (socket_fd >= 0) + dont_close[n_dont_close++] = socket_fd; + if (n_fds > 0) { + memcpy(dont_close + n_dont_close, fds, sizeof(int) * n_fds); + n_dont_close += n_fds; + } + + if (runtime) + append_socket_pair(dont_close, &n_dont_close, runtime->ephemeral_storage_socket); + + if (runtime && runtime->shared) { + append_socket_pair(dont_close, &n_dont_close, runtime->shared->netns_storage_socket); + append_socket_pair(dont_close, &n_dont_close, runtime->shared->ipcns_storage_socket); + } + + if (runtime && runtime->dynamic_creds) { + if (runtime->dynamic_creds->user) + append_socket_pair(dont_close, &n_dont_close, runtime->dynamic_creds->user->storage_socket); + if (runtime->dynamic_creds->group) + append_socket_pair(dont_close, &n_dont_close, runtime->dynamic_creds->group->storage_socket); + } + + if (params->user_lookup_fd >= 0) + dont_close[n_dont_close++] = params->user_lookup_fd; + + return close_all_fds(dont_close, n_dont_close); +} + +static int send_user_lookup( + const char *unit_id, + int user_lookup_fd, + uid_t uid, + gid_t gid) { + + assert(unit_id); + + /* Send the resolved UID/GID to PID 1 after we learnt it. We send a single datagram, containing the UID/GID + * data as well as the unit name. Note that we suppress sending this if no user/group to resolve was + * specified. */ + + if (user_lookup_fd < 0) + return 0; + + if (!uid_is_valid(uid) && !gid_is_valid(gid)) + return 0; + + if (writev(user_lookup_fd, + (struct iovec[]) { + IOVEC_MAKE(&uid, sizeof(uid)), + IOVEC_MAKE(&gid, sizeof(gid)), + IOVEC_MAKE_STRING(unit_id) }, 3) < 0) + return -errno; + + return 0; +} + +static int acquire_home(const ExecContext *c, uid_t uid, const char** home, char **buf) { + int r; + + assert(c); + assert(home); + assert(buf); + + /* If WorkingDirectory=~ is set, try to acquire a usable home directory. */ + + if (*home) + return 0; + + if (!c->working_directory_home) + return 0; + + r = get_home_dir(buf); + if (r < 0) + return r; + + *home = *buf; + return 1; +} + +static int compile_suggested_paths(const ExecContext *c, const ExecParameters *p, char ***ret) { + _cleanup_strv_free_ char ** list = NULL; + int r; + + assert(c); + assert(p); + assert(ret); + + assert(c->dynamic_user); + + /* Compile a list of paths that it might make sense to read the owning UID from to use as initial candidate for + * dynamic UID allocation, in order to save us from doing costly recursive chown()s of the special + * directories. */ + + for (ExecDirectoryType t = 0; t < _EXEC_DIRECTORY_TYPE_MAX; t++) { + if (t == EXEC_DIRECTORY_CONFIGURATION) + continue; + + if (!p->prefix[t]) + continue; + + for (size_t i = 0; i < c->directories[t].n_items; i++) { + char *e; + + if (exec_directory_is_private(c, t)) + e = path_join(p->prefix[t], "private", c->directories[t].items[i].path); + else + e = path_join(p->prefix[t], c->directories[t].items[i].path); + if (!e) + return -ENOMEM; + + r = strv_consume(&list, e); + if (r < 0) + return r; + } + } + + *ret = TAKE_PTR(list); + + return 0; +} + +static int exec_context_cpu_affinity_from_numa(const ExecContext *c, CPUSet *ret) { + _cleanup_(cpu_set_reset) CPUSet s = {}; + int r; + + assert(c); + assert(ret); + + if (!c->numa_policy.nodes.set) { + log_debug("Can't derive CPU affinity mask from NUMA mask because NUMA mask is not set, ignoring"); + return 0; + } + + r = numa_to_cpu_set(&c->numa_policy, &s); + if (r < 0) + return r; + + cpu_set_reset(ret); + + return cpu_set_add_all(ret, &s); +} + +static int add_shifted_fd(int *fds, size_t fds_size, size_t *n_fds, int *fd) { + int r; + + assert(fds); + assert(n_fds); + assert(*n_fds < fds_size); + assert(fd); + + if (*fd < 0) + return 0; + + if (*fd < 3 + (int) *n_fds) { + /* Let's move the fd up, so that it's outside of the fd range we will use to store + * the fds we pass to the process (or which are closed only during execve). */ + + r = fcntl(*fd, F_DUPFD_CLOEXEC, 3 + (int) *n_fds); + if (r < 0) + return -errno; + + close_and_replace(*fd, r); + } + + fds[(*n_fds)++] = *fd; + return 1; +} + +static int connect_unix_harder(const ExecContext *c, const ExecParameters *p, const OpenFile *of, int ofd) { + union sockaddr_union addr = { + .un.sun_family = AF_UNIX, + }; + socklen_t sa_len; + static const int socket_types[] = { SOCK_DGRAM, SOCK_STREAM, SOCK_SEQPACKET }; + int r; + + assert(c); + assert(p); + assert(of); + assert(ofd >= 0); + + r = sockaddr_un_set_path(&addr.un, FORMAT_PROC_FD_PATH(ofd)); + if (r < 0) + return log_exec_error_errno(c, p, r, "Failed to set sockaddr for %s: %m", of->path); + + sa_len = r; + + for (size_t i = 0; i < ELEMENTSOF(socket_types); i++) { + _cleanup_close_ int fd = -EBADF; + + fd = socket(AF_UNIX, socket_types[i] | SOCK_CLOEXEC, 0); + if (fd < 0) + return log_exec_error_errno(c, + p, + errno, + "Failed to create socket for %s: %m", + of->path); + + r = RET_NERRNO(connect(fd, &addr.sa, sa_len)); + if (r == -EPROTOTYPE) + continue; + if (r < 0) + return log_exec_error_errno(c, + p, + r, + "Failed to connect socket for %s: %m", + of->path); + + return TAKE_FD(fd); + } + + return log_exec_error_errno(c, + p, + SYNTHETIC_ERRNO(EPROTOTYPE), "Failed to connect socket for \"%s\".", + of->path); +} + +static int get_open_file_fd(const ExecContext *c, const ExecParameters *p, const OpenFile *of) { + struct stat st; + _cleanup_close_ int fd = -EBADF, ofd = -EBADF; + + assert(c); + assert(p); + assert(of); + + ofd = open(of->path, O_PATH | O_CLOEXEC); + if (ofd < 0) + return log_exec_error_errno(c, p, errno, "Could not open \"%s\": %m", of->path); + + if (fstat(ofd, &st) < 0) + return log_exec_error_errno(c, p, errno, "Failed to stat %s: %m", of->path); + + if (S_ISSOCK(st.st_mode)) { + fd = connect_unix_harder(c, p, of, ofd); + if (fd < 0) + return fd; + + if (FLAGS_SET(of->flags, OPENFILE_READ_ONLY) && shutdown(fd, SHUT_WR) < 0) + return log_exec_error_errno(c, p, errno, "Failed to shutdown send for socket %s: %m", + of->path); + + log_exec_debug(c, p, "socket %s opened (fd=%d)", of->path, fd); + } else { + int flags = FLAGS_SET(of->flags, OPENFILE_READ_ONLY) ? O_RDONLY : O_RDWR; + if (FLAGS_SET(of->flags, OPENFILE_APPEND)) + flags |= O_APPEND; + else if (FLAGS_SET(of->flags, OPENFILE_TRUNCATE)) + flags |= O_TRUNC; + + fd = fd_reopen(ofd, flags | O_CLOEXEC); + if (fd < 0) + return log_exec_error_errno(c, p, fd, "Failed to open file %s: %m", of->path); + + log_exec_debug(c, p, "file %s opened (fd=%d)", of->path, fd); + } + + return TAKE_FD(fd); +} + +static int collect_open_file_fds(const ExecContext *c, ExecParameters *p, size_t *n_fds) { + int r; + + assert(c); + assert(p); + assert(n_fds); + + LIST_FOREACH(open_files, of, p->open_files) { + _cleanup_close_ int fd = -EBADF; + + fd = get_open_file_fd(c, p, of); + if (fd < 0) { + if (FLAGS_SET(of->flags, OPENFILE_GRACEFUL)) { + log_exec_debug_errno(c, p, fd, "Failed to get OpenFile= file descriptor for %s, ignoring: %m", of->path); + continue; + } + + return fd; + } + + if (!GREEDY_REALLOC(p->fds, *n_fds + 1)) + return -ENOMEM; + + r = strv_extend(&p->fd_names, of->fdname); + if (r < 0) + return r; + + p->fds[*n_fds] = TAKE_FD(fd); + + (*n_fds)++; + } + + return 0; +} + +static void log_command_line( + const ExecContext *context, + const ExecParameters *params, + const char *msg, + const char *executable, + char **argv) { + + assert(context); + assert(params); + assert(msg); + assert(executable); + + if (!DEBUG_LOGGING) + return; + + _cleanup_free_ char *cmdline = quote_command_line(argv, SHELL_ESCAPE_EMPTY); + + log_exec_struct(context, params, LOG_DEBUG, + "EXECUTABLE=%s", executable, + LOG_EXEC_MESSAGE(params, "%s: %s", msg, strnull(cmdline)), + LOG_EXEC_INVOCATION_ID(params)); +} + +static bool exec_context_need_unprivileged_private_users( + const ExecContext *context, + const ExecParameters *params) { + + assert(context); + assert(params); + + /* These options require PrivateUsers= when used in user units, as we need to be in a user namespace + * to have permission to enable them when not running as root. If we have effective CAP_SYS_ADMIN + * (system manager) then we have privileges and don't need this. */ + if (params->runtime_scope != RUNTIME_SCOPE_USER) + return false; + + return context->private_users || + context->private_tmp || + context->private_devices || + context->private_network || + context->network_namespace_path || + context->private_ipc || + context->ipc_namespace_path || + context->private_mounts > 0 || + context->mount_apivfs || + context->n_bind_mounts > 0 || + context->n_temporary_filesystems > 0 || + context->root_directory || + !strv_isempty(context->extension_directories) || + context->protect_system != PROTECT_SYSTEM_NO || + context->protect_home != PROTECT_HOME_NO || + context->protect_kernel_tunables || + context->protect_kernel_modules || + context->protect_kernel_logs || + context->protect_control_groups || + context->protect_clock || + context->protect_hostname || + !strv_isempty(context->read_write_paths) || + !strv_isempty(context->read_only_paths) || + !strv_isempty(context->inaccessible_paths) || + !strv_isempty(context->exec_paths) || + !strv_isempty(context->no_exec_paths); +} + +static bool exec_context_shall_confirm_spawn(const ExecContext *context) { + assert(context); + + if (confirm_spawn_disabled()) + return false; + + /* For some reasons units remaining in the same process group + * as PID 1 fail to acquire the console even if it's not used + * by any process. So skip the confirmation question for them. */ + return !context->same_pgrp; +} + +static int exec_context_named_iofds( + const ExecContext *c, + const ExecParameters *p, + int named_iofds[static 3]) { + + size_t targets; + const char* stdio_fdname[3]; + size_t n_fds; + + assert(c); + assert(p); + assert(named_iofds); + + targets = (c->std_input == EXEC_INPUT_NAMED_FD) + + (c->std_output == EXEC_OUTPUT_NAMED_FD) + + (c->std_error == EXEC_OUTPUT_NAMED_FD); + + for (size_t i = 0; i < 3; i++) + stdio_fdname[i] = exec_context_fdname(c, i); + + n_fds = p->n_storage_fds + p->n_socket_fds; + + for (size_t i = 0; i < n_fds && targets > 0; i++) + if (named_iofds[STDIN_FILENO] < 0 && + c->std_input == EXEC_INPUT_NAMED_FD && + stdio_fdname[STDIN_FILENO] && + streq(p->fd_names[i], stdio_fdname[STDIN_FILENO])) { + + named_iofds[STDIN_FILENO] = p->fds[i]; + targets--; + + } else if (named_iofds[STDOUT_FILENO] < 0 && + c->std_output == EXEC_OUTPUT_NAMED_FD && + stdio_fdname[STDOUT_FILENO] && + streq(p->fd_names[i], stdio_fdname[STDOUT_FILENO])) { + + named_iofds[STDOUT_FILENO] = p->fds[i]; + targets--; + + } else if (named_iofds[STDERR_FILENO] < 0 && + c->std_error == EXEC_OUTPUT_NAMED_FD && + stdio_fdname[STDERR_FILENO] && + streq(p->fd_names[i], stdio_fdname[STDERR_FILENO])) { + + named_iofds[STDERR_FILENO] = p->fds[i]; + targets--; + } + + return targets == 0 ? 0 : -ENOENT; +} + +static void exec_shared_runtime_close(ExecSharedRuntime *shared) { + if (!shared) + return; + + safe_close_pair(shared->netns_storage_socket); + safe_close_pair(shared->ipcns_storage_socket); +} + +static void exec_runtime_close(ExecRuntime *rt) { + if (!rt) + return; + + safe_close_pair(rt->ephemeral_storage_socket); + + exec_shared_runtime_close(rt->shared); + dynamic_creds_close(rt->dynamic_creds); +} + +static void exec_params_close(ExecParameters *p) { + if (!p) + return; + + p->stdin_fd = safe_close(p->stdin_fd); + p->stdout_fd = safe_close(p->stdout_fd); + p->stderr_fd = safe_close(p->stderr_fd); +} + +int exec_invoke( + const ExecCommand *command, + const ExecContext *context, + ExecParameters *params, + ExecRuntime *runtime, + const CGroupContext *cgroup_context, + int *exit_status) { + + _cleanup_strv_free_ char **our_env = NULL, **pass_env = NULL, **joined_exec_search_path = NULL, **accum_env = NULL, **replaced_argv = NULL; + int r, ngids = 0; + _cleanup_free_ gid_t *supplementary_gids = NULL; + const char *username = NULL, *groupname = NULL; + _cleanup_free_ char *home_buffer = NULL, *memory_pressure_path = NULL; + const char *home = NULL, *shell = NULL; + char **final_argv = NULL; + dev_t journal_stream_dev = 0; + ino_t journal_stream_ino = 0; + bool userns_set_up = false; + bool needs_sandboxing, /* Do we need to set up full sandboxing? (i.e. all namespacing, all MAC stuff, caps, yadda yadda */ + needs_setuid, /* Do we need to do the actual setresuid()/setresgid() calls? */ + needs_mount_namespace, /* Do we need to set up a mount namespace for this kernel? */ + needs_ambient_hack; /* Do we need to apply the ambient capabilities hack? */ + bool keep_seccomp_privileges = false; +#if HAVE_SELINUX + _cleanup_free_ char *mac_selinux_context_net = NULL; + bool use_selinux = false; +#endif +#if ENABLE_SMACK + bool use_smack = false; +#endif +#if HAVE_APPARMOR + bool use_apparmor = false; +#endif +#if HAVE_SECCOMP + uint64_t saved_bset = 0; +#endif + uid_t saved_uid = getuid(); + gid_t saved_gid = getgid(); + uid_t uid = UID_INVALID; + gid_t gid = GID_INVALID; + size_t n_fds, /* fds to pass to the child */ + n_keep_fds; /* total number of fds not to close */ + int secure_bits; + _cleanup_free_ gid_t *gids_after_pam = NULL; + int ngids_after_pam = 0; + + int socket_fd = -EBADF, named_iofds[3] = EBADF_TRIPLET; + size_t n_storage_fds, n_socket_fds; + + assert(command); + assert(context); + assert(params); + assert(exit_status); + + if (context->log_level_max >= 0) + log_set_max_level(context->log_level_max); + + /* Explicitly test for CVE-2021-4034 inspired invocations */ + if (!command->path || strv_isempty(command->argv)) { + *exit_status = EXIT_EXEC; + return log_exec_error_errno( + context, + params, + SYNTHETIC_ERRNO(EINVAL), + "Invalid command line arguments."); + } + + LOG_CONTEXT_PUSH_EXEC(context, params); + + if (context->std_input == EXEC_INPUT_SOCKET || + context->std_output == EXEC_OUTPUT_SOCKET || + context->std_error == EXEC_OUTPUT_SOCKET) { + + if (params->n_socket_fds > 1) + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EINVAL), "Got more than one socket."); + + if (params->n_socket_fds == 0) + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EINVAL), "Got no socket."); + + socket_fd = params->fds[0]; + n_storage_fds = n_socket_fds = 0; + } else { + n_socket_fds = params->n_socket_fds; + n_storage_fds = params->n_storage_fds; + } + n_fds = n_socket_fds + n_storage_fds; + + r = exec_context_named_iofds(context, params, named_iofds); + if (r < 0) + return log_exec_error_errno(context, params, r, "Failed to load a named file descriptor: %m"); + + rename_process_from_path(command->path); + + /* We reset exactly these signals, since they are the only ones we set to SIG_IGN in the main + * daemon. All others we leave untouched because we set them to SIG_DFL or a valid handler initially, + * both of which will be demoted to SIG_DFL. */ + (void) default_signals(SIGNALS_CRASH_HANDLER, + SIGNALS_IGNORE); + + if (context->ignore_sigpipe) + (void) ignore_signals(SIGPIPE); + + r = reset_signal_mask(); + if (r < 0) { + *exit_status = EXIT_SIGNAL_MASK; + return log_exec_error_errno(context, params, r, "Failed to set process signal mask: %m"); + } + + if (params->idle_pipe) + do_idle_pipe_dance(params->idle_pipe); + + /* Close fds we don't need very early to make sure we don't block init reexecution because it cannot bind its + * sockets. Among the fds we close are the logging fds, and we want to keep them closed, so that we don't have + * any fds open we don't really want open during the transition. In order to make logging work, we switch the + * log subsystem into open_when_needed mode, so that it reopens the logs on every single log call. */ + + log_forget_fds(); + log_set_open_when_needed(true); + log_settle_target(); + + /* In case anything used libc syslog(), close this here, too */ + closelog(); + + r = collect_open_file_fds(context, params, &n_fds); + if (r < 0) { + *exit_status = EXIT_FDS; + return log_exec_error_errno(context, params, r, "Failed to get OpenFile= file descriptors: %m"); + } + + int keep_fds[n_fds + 3]; + memcpy_safe(keep_fds, params->fds, n_fds * sizeof(int)); + n_keep_fds = n_fds; + + r = add_shifted_fd(keep_fds, ELEMENTSOF(keep_fds), &n_keep_fds, ¶ms->exec_fd); + if (r < 0) { + *exit_status = EXIT_FDS; + return log_exec_error_errno(context, params, r, "Failed to collect shifted fd: %m"); + } + +#if HAVE_LIBBPF + r = add_shifted_fd(keep_fds, ELEMENTSOF(keep_fds), &n_keep_fds, ¶ms->bpf_outer_map_fd); + if (r < 0) { + *exit_status = EXIT_FDS; + return log_exec_error_errno(context, params, r, "Failed to collect shifted fd: %m"); + } +#endif + + r = close_remaining_fds(params, runtime, socket_fd, keep_fds, n_keep_fds); + if (r < 0) { + *exit_status = EXIT_FDS; + return log_exec_error_errno(context, params, r, "Failed to close unwanted file descriptors: %m"); + } + + if (!context->same_pgrp && + setsid() < 0) { + *exit_status = EXIT_SETSID; + return log_exec_error_errno(context, params, errno, "Failed to create new process session: %m"); + } + + exec_context_tty_reset(context, params); + + if (params->shall_confirm_spawn && exec_context_shall_confirm_spawn(context)) { + _cleanup_free_ char *cmdline = NULL; + + cmdline = quote_command_line(command->argv, SHELL_ESCAPE_EMPTY); + if (!cmdline) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + + r = ask_for_confirmation(context, params, cmdline); + if (r != CONFIRM_EXECUTE) { + if (r == CONFIRM_PRETEND_SUCCESS) { + *exit_status = EXIT_SUCCESS; + return 0; + } + + *exit_status = EXIT_CONFIRM; + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(ECANCELED), + "Execution cancelled by the user"); + } + } + + /* We are about to invoke NSS and PAM modules. Let's tell them what we are doing here, maybe they care. This is + * used by nss-resolve to disable itself when we are about to start systemd-resolved, to avoid deadlocks. Note + * that these env vars do not survive the execve(), which means they really only apply to the PAM and NSS + * invocations themselves. Also note that while we'll only invoke NSS modules involved in user management they + * might internally call into other NSS modules that are involved in hostname resolution, we never know. */ + if (setenv("SYSTEMD_ACTIVATION_UNIT", params->unit_id, true) != 0 || + setenv("SYSTEMD_ACTIVATION_SCOPE", runtime_scope_to_string(params->runtime_scope), true) != 0) { + *exit_status = EXIT_MEMORY; + return log_exec_error_errno(context, params, errno, "Failed to update environment: %m"); + } + + if (context->dynamic_user && runtime && runtime->dynamic_creds) { + _cleanup_strv_free_ char **suggested_paths = NULL; + + /* On top of that, make sure we bypass our own NSS module nss-systemd comprehensively for any NSS + * checks, if DynamicUser=1 is used, as we shouldn't create a feedback loop with ourselves here. */ + if (putenv((char*) "SYSTEMD_NSS_DYNAMIC_BYPASS=1") != 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, errno, "Failed to update environment: %m"); + } + + r = compile_suggested_paths(context, params, &suggested_paths); + if (r < 0) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + + r = dynamic_creds_realize(runtime->dynamic_creds, suggested_paths, &uid, &gid); + if (r < 0) { + *exit_status = EXIT_USER; + if (r == -EILSEQ) + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EOPNOTSUPP), + "Failed to update dynamic user credentials: User or group with specified name already exists."); + return log_exec_error_errno(context, params, r, "Failed to update dynamic user credentials: %m"); + } + + if (!uid_is_valid(uid)) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(ESRCH), "UID validation failed for \""UID_FMT"\"", uid); + } + + if (!gid_is_valid(gid)) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(ESRCH), "GID validation failed for \""GID_FMT"\"", gid); + } + + if (runtime->dynamic_creds->user) + username = runtime->dynamic_creds->user->name; + + } else { + if (context->user) { + r = get_fixed_user(context->user, &username, &uid, &gid, &home, &shell); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to determine user credentials: %m"); + } + } + + if (context->group) { + r = get_fixed_group(context->group, &groupname, &gid); + if (r < 0) { + *exit_status = EXIT_GROUP; + return log_exec_error_errno(context, params, r, "Failed to determine group credentials: %m"); + } + } + } + + /* Initialize user supplementary groups and get SupplementaryGroups= ones */ + r = get_supplementary_groups(context, username, groupname, gid, + &supplementary_gids, &ngids); + if (r < 0) { + *exit_status = EXIT_GROUP; + return log_exec_error_errno(context, params, r, "Failed to determine supplementary groups: %m"); + } + + r = send_user_lookup(params->unit_id, params->user_lookup_fd, uid, gid); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to send user credentials to PID1: %m"); + } + + params->user_lookup_fd = safe_close(params->user_lookup_fd); + + r = acquire_home(context, uid, &home, &home_buffer); + if (r < 0) { + *exit_status = EXIT_CHDIR; + return log_exec_error_errno(context, params, r, "Failed to determine $HOME for user: %m"); + } + + /* If a socket is connected to STDIN/STDOUT/STDERR, we must drop O_NONBLOCK */ + if (socket_fd >= 0) + (void) fd_nonblock(socket_fd, false); + + /* Journald will try to look-up our cgroup in order to populate _SYSTEMD_CGROUP and _SYSTEMD_UNIT fields. + * Hence we need to migrate to the target cgroup from init.scope before connecting to journald */ + if (params->cgroup_path) { + _cleanup_free_ char *p = NULL; + + r = exec_params_get_cgroup_path(params, cgroup_context, &p); + if (r < 0) { + *exit_status = EXIT_CGROUP; + return log_exec_error_errno(context, params, r, "Failed to acquire cgroup path: %m"); + } + + r = cg_attach_everywhere(params->cgroup_supported, p, 0, NULL, NULL); + if (r == -EUCLEAN) { + *exit_status = EXIT_CGROUP; + return log_exec_error_errno(context, params, r, "Failed to attach process to cgroup %s " + "because the cgroup or one of its parents or " + "siblings is in the threaded mode: %m", p); + } + if (r < 0) { + *exit_status = EXIT_CGROUP; + return log_exec_error_errno(context, params, r, "Failed to attach to cgroup %s: %m", p); + } + } + + if (context->network_namespace_path && runtime && runtime->shared && runtime->shared->netns_storage_socket[0] >= 0) { + r = open_shareable_ns_path(runtime->shared->netns_storage_socket, context->network_namespace_path, CLONE_NEWNET); + if (r < 0) { + *exit_status = EXIT_NETWORK; + return log_exec_error_errno(context, params, r, "Failed to open network namespace path %s: %m", context->network_namespace_path); + } + } + + if (context->ipc_namespace_path && runtime && runtime->shared && runtime->shared->ipcns_storage_socket[0] >= 0) { + r = open_shareable_ns_path(runtime->shared->ipcns_storage_socket, context->ipc_namespace_path, CLONE_NEWIPC); + if (r < 0) { + *exit_status = EXIT_NAMESPACE; + return log_exec_error_errno(context, params, r, "Failed to open IPC namespace path %s: %m", context->ipc_namespace_path); + } + } + + r = setup_input(context, params, socket_fd, named_iofds); + if (r < 0) { + *exit_status = EXIT_STDIN; + return log_exec_error_errno(context, params, r, "Failed to set up standard input: %m"); + } + + r = setup_output(context, params, STDOUT_FILENO, socket_fd, named_iofds, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino); + if (r < 0) { + *exit_status = EXIT_STDOUT; + return log_exec_error_errno(context, params, r, "Failed to set up standard output: %m"); + } + + r = setup_output(context, params, STDERR_FILENO, socket_fd, named_iofds, basename(command->path), uid, gid, &journal_stream_dev, &journal_stream_ino); + if (r < 0) { + *exit_status = EXIT_STDERR; + return log_exec_error_errno(context, params, r, "Failed to set up standard error output: %m"); + } + + if (context->oom_score_adjust_set) { + /* When we can't make this change due to EPERM, then let's silently skip over it. User + * namespaces prohibit write access to this file, and we shouldn't trip up over that. */ + r = set_oom_score_adjust(context->oom_score_adjust); + if (ERRNO_IS_NEG_PRIVILEGE(r)) + log_exec_debug_errno(context, params, r, + "Failed to adjust OOM setting, assuming containerized execution, ignoring: %m"); + else if (r < 0) { + *exit_status = EXIT_OOM_ADJUST; + return log_exec_error_errno(context, params, r, "Failed to adjust OOM setting: %m"); + } + } + + if (context->coredump_filter_set) { + r = set_coredump_filter(context->coredump_filter); + if (ERRNO_IS_NEG_PRIVILEGE(r)) + log_exec_debug_errno(context, params, r, "Failed to adjust coredump_filter, ignoring: %m"); + else if (r < 0) { + *exit_status = EXIT_LIMITS; + return log_exec_error_errno(context, params, r, "Failed to adjust coredump_filter: %m"); + } + } + + if (context->nice_set) { + r = setpriority_closest(context->nice); + if (r < 0) { + *exit_status = EXIT_NICE; + return log_exec_error_errno(context, params, r, "Failed to set up process scheduling priority (nice level): %m"); + } + } + + if (context->cpu_sched_set) { + struct sched_param param = { + .sched_priority = context->cpu_sched_priority, + }; + + r = sched_setscheduler(0, + context->cpu_sched_policy | + (context->cpu_sched_reset_on_fork ? + SCHED_RESET_ON_FORK : 0), + ¶m); + if (r < 0) { + *exit_status = EXIT_SETSCHEDULER; + return log_exec_error_errno(context, params, errno, "Failed to set up CPU scheduling: %m"); + } + } + + if (context->cpu_affinity_from_numa || context->cpu_set.set) { + _cleanup_(cpu_set_reset) CPUSet converted_cpu_set = {}; + const CPUSet *cpu_set; + + if (context->cpu_affinity_from_numa) { + r = exec_context_cpu_affinity_from_numa(context, &converted_cpu_set); + if (r < 0) { + *exit_status = EXIT_CPUAFFINITY; + return log_exec_error_errno(context, params, r, "Failed to derive CPU affinity mask from NUMA mask: %m"); + } + + cpu_set = &converted_cpu_set; + } else + cpu_set = &context->cpu_set; + + if (sched_setaffinity(0, cpu_set->allocated, cpu_set->set) < 0) { + *exit_status = EXIT_CPUAFFINITY; + return log_exec_error_errno(context, params, errno, "Failed to set up CPU affinity: %m"); + } + } + + if (mpol_is_valid(numa_policy_get_type(&context->numa_policy))) { + r = apply_numa_policy(&context->numa_policy); + if (ERRNO_IS_NEG_NOT_SUPPORTED(r)) + log_exec_debug_errno(context, params, r, "NUMA support not available, ignoring."); + else if (r < 0) { + *exit_status = EXIT_NUMA_POLICY; + return log_exec_error_errno(context, params, r, "Failed to set NUMA memory policy: %m"); + } + } + + if (context->ioprio_set) + if (ioprio_set(IOPRIO_WHO_PROCESS, 0, context->ioprio) < 0) { + *exit_status = EXIT_IOPRIO; + return log_exec_error_errno(context, params, errno, "Failed to set up IO scheduling priority: %m"); + } + + if (context->timer_slack_nsec != NSEC_INFINITY) + if (prctl(PR_SET_TIMERSLACK, context->timer_slack_nsec) < 0) { + *exit_status = EXIT_TIMERSLACK; + return log_exec_error_errno(context, params, errno, "Failed to set up timer slack: %m"); + } + + if (context->personality != PERSONALITY_INVALID) { + r = safe_personality(context->personality); + if (r < 0) { + *exit_status = EXIT_PERSONALITY; + return log_exec_error_errno(context, params, r, "Failed to set up execution domain (personality): %m"); + } + } + +#if ENABLE_UTMP + if (context->utmp_id) { + _cleanup_free_ char *username_alloc = NULL; + + if (!username && context->utmp_mode == EXEC_UTMP_USER) { + username_alloc = uid_to_name(uid_is_valid(uid) ? uid : saved_uid); + if (!username_alloc) { + *exit_status = EXIT_USER; + return log_oom(); + } + } + + const char *line = context->tty_path ? + (path_startswith(context->tty_path, "/dev/") ?: context->tty_path) : + NULL; + utmp_put_init_process(context->utmp_id, getpid_cached(), getsid(0), + line, + context->utmp_mode == EXEC_UTMP_INIT ? INIT_PROCESS : + context->utmp_mode == EXEC_UTMP_LOGIN ? LOGIN_PROCESS : + USER_PROCESS, + username ?: username_alloc); + } +#endif + + if (uid_is_valid(uid)) { + r = chown_terminal(STDIN_FILENO, uid); + if (r < 0) { + *exit_status = EXIT_STDIN; + return log_exec_error_errno(context, params, r, "Failed to change ownership of terminal: %m"); + } + } + + if (params->cgroup_path) { + /* If delegation is enabled we'll pass ownership of the cgroup to the user of the new process. On cgroup v1 + * this is only about systemd's own hierarchy, i.e. not the controller hierarchies, simply because that's not + * safe. On cgroup v2 there's only one hierarchy anyway, and delegation is safe there, hence in that case only + * touch a single hierarchy too. */ + + if (params->flags & EXEC_CGROUP_DELEGATE) { + _cleanup_free_ char *p = NULL; + + r = cg_set_access(SYSTEMD_CGROUP_CONTROLLER, params->cgroup_path, uid, gid); + if (r < 0) { + *exit_status = EXIT_CGROUP; + return log_exec_error_errno(context, params, r, "Failed to adjust control group access: %m"); + } + + r = exec_params_get_cgroup_path(params, cgroup_context, &p); + if (r < 0) { + *exit_status = EXIT_CGROUP; + return log_exec_error_errno(context, params, r, "Failed to acquire cgroup path: %m"); + } + if (r > 0) { + r = cg_set_access_recursive(SYSTEMD_CGROUP_CONTROLLER, p, uid, gid); + if (r < 0) { + *exit_status = EXIT_CGROUP; + return log_exec_error_errno(context, params, r, "Failed to adjust control subgroup access: %m"); + } + } + } + + if (cgroup_context && cg_unified() > 0 && is_pressure_supported() > 0) { + if (cgroup_context_want_memory_pressure(cgroup_context)) { + r = cg_get_path("memory", params->cgroup_path, "memory.pressure", &memory_pressure_path); + if (r < 0) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + + r = chmod_and_chown(memory_pressure_path, 0644, uid, gid); + if (r < 0) { + log_exec_full_errno(context, params, r == -ENOENT || ERRNO_IS_PRIVILEGE(r) ? LOG_DEBUG : LOG_WARNING, r, + "Failed to adjust ownership of '%s', ignoring: %m", memory_pressure_path); + memory_pressure_path = mfree(memory_pressure_path); + } + } else if (cgroup_context->memory_pressure_watch == CGROUP_PRESSURE_WATCH_OFF) { + memory_pressure_path = strdup("/dev/null"); /* /dev/null is explicit indicator for turning of memory pressure watch */ + if (!memory_pressure_path) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + } + } + } + + needs_mount_namespace = exec_needs_mount_namespace(context, params, runtime); + + for (ExecDirectoryType dt = 0; dt < _EXEC_DIRECTORY_TYPE_MAX; dt++) { + r = setup_exec_directory(context, params, uid, gid, dt, needs_mount_namespace, exit_status); + if (r < 0) + return log_exec_error_errno(context, params, r, "Failed to set up special execution directory in %s: %m", params->prefix[dt]); + } + + if (FLAGS_SET(params->flags, EXEC_WRITE_CREDENTIALS)) { + r = exec_setup_credentials(context, params, params->unit_id, uid, gid); + if (r < 0) { + *exit_status = EXIT_CREDENTIALS; + return log_exec_error_errno(context, params, r, "Failed to set up credentials: %m"); + } + } + + r = build_environment( + context, + params, + cgroup_context, + n_fds, + home, + username, + shell, + journal_stream_dev, + journal_stream_ino, + memory_pressure_path, + &our_env); + if (r < 0) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + + r = build_pass_environment(context, &pass_env); + if (r < 0) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + + /* The $PATH variable is set to the default path in params->environment. However, this is overridden + * if user-specified fields have $PATH set. The intention is to also override $PATH if the unit does + * not specify PATH but the unit has ExecSearchPath. */ + if (!strv_isempty(context->exec_search_path)) { + _cleanup_free_ char *joined = NULL; + + joined = strv_join(context->exec_search_path, ":"); + if (!joined) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + + r = strv_env_assign(&joined_exec_search_path, "PATH", joined); + if (r < 0) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + } + + accum_env = strv_env_merge(params->environment, + our_env, + joined_exec_search_path, + pass_env, + context->environment, + params->files_env); + if (!accum_env) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + accum_env = strv_env_clean(accum_env); + + (void) umask(context->umask); + + r = setup_keyring(context, params, uid, gid); + if (r < 0) { + *exit_status = EXIT_KEYRING; + return log_exec_error_errno(context, params, r, "Failed to set up kernel keyring: %m"); + } + + /* We need sandboxing if the caller asked us to apply it and the command isn't explicitly excepted + * from it. */ + needs_sandboxing = (params->flags & EXEC_APPLY_SANDBOXING) && !(command->flags & EXEC_COMMAND_FULLY_PRIVILEGED); + + /* We need the ambient capability hack, if the caller asked us to apply it and the command is marked + * for it, and the kernel doesn't actually support ambient caps. */ + needs_ambient_hack = (params->flags & EXEC_APPLY_SANDBOXING) && (command->flags & EXEC_COMMAND_AMBIENT_MAGIC) && !ambient_capabilities_supported(); + + /* We need setresuid() if the caller asked us to apply sandboxing and the command isn't explicitly + * excepted from either whole sandboxing or just setresuid() itself, and the ambient hack is not + * desired. */ + if (needs_ambient_hack) + needs_setuid = false; + else + needs_setuid = (params->flags & EXEC_APPLY_SANDBOXING) && !(command->flags & (EXEC_COMMAND_FULLY_PRIVILEGED|EXEC_COMMAND_NO_SETUID)); + + uint64_t capability_ambient_set = context->capability_ambient_set; + + if (needs_sandboxing) { + /* MAC enablement checks need to be done before a new mount ns is created, as they rely on + * /sys being present. The actual MAC context application will happen later, as late as + * possible, to avoid impacting our own code paths. */ + +#if HAVE_SELINUX + use_selinux = mac_selinux_use(); +#endif +#if ENABLE_SMACK + use_smack = mac_smack_use(); +#endif +#if HAVE_APPARMOR + use_apparmor = mac_apparmor_use(); +#endif + } + + if (needs_sandboxing) { + int which_failed; + + /* Let's set the resource limits before we call into PAM, so that pam_limits wins over what + * is set here. (See below.) */ + + r = setrlimit_closest_all((const struct rlimit* const *) context->rlimit, &which_failed); + if (r < 0) { + *exit_status = EXIT_LIMITS; + return log_exec_error_errno(context, params, r, "Failed to adjust resource limit RLIMIT_%s: %m", rlimit_to_string(which_failed)); + } + } + + if (needs_setuid && context->pam_name && username) { + /* Let's call into PAM after we set up our own idea of resource limits so that pam_limits + * wins here. (See above.) */ + + /* All fds passed in the fds array will be closed in the pam child process. */ + r = setup_pam(context->pam_name, username, uid, gid, context->tty_path, &accum_env, params->fds, n_fds); + if (r < 0) { + *exit_status = EXIT_PAM; + return log_exec_error_errno(context, params, r, "Failed to set up PAM session: %m"); + } + + if (ambient_capabilities_supported()) { + uint64_t ambient_after_pam; + + /* PAM modules might have set some ambient caps. Query them here and merge them into + * the caps we want to set in the end, so that we don't end up unsetting them. */ + r = capability_get_ambient(&ambient_after_pam); + if (r < 0) { + *exit_status = EXIT_CAPABILITIES; + return log_exec_error_errno(context, params, r, "Failed to query ambient caps: %m"); + } + + capability_ambient_set |= ambient_after_pam; + } + + ngids_after_pam = getgroups_alloc(&gids_after_pam); + if (ngids_after_pam < 0) { + *exit_status = EXIT_GROUP; + return log_exec_error_errno(context, params, ngids_after_pam, "Failed to obtain groups after setting up PAM: %m"); + } + } + + if (needs_sandboxing && exec_context_need_unprivileged_private_users(context, params)) { + /* If we're unprivileged, set up the user namespace first to enable use of the other namespaces. + * Users with CAP_SYS_ADMIN can set up user namespaces last because they will be able to + * set up all of the other namespaces (i.e. network, mount, UTS) without a user namespace. */ + + r = setup_private_users(saved_uid, saved_gid, uid, gid); + /* If it was requested explicitly and we can't set it up, fail early. Otherwise, continue and let + * the actual requested operations fail (or silently continue). */ + if (r < 0 && context->private_users) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to set up user namespacing for unprivileged user: %m"); + } + if (r < 0) + log_exec_info_errno(context, params, r, "Failed to set up user namespacing for unprivileged user, ignoring: %m"); + else + userns_set_up = true; + } + + if (exec_needs_network_namespace(context) && runtime && runtime->shared && runtime->shared->netns_storage_socket[0] >= 0) { + + /* Try to enable network namespacing if network namespacing is available and we have + * CAP_NET_ADMIN. We need CAP_NET_ADMIN to be able to configure the loopback device in the + * new network namespace. And if we don't have that, then we could only create a network + * namespace without the ability to set up "lo". Hence gracefully skip things then. */ + if (ns_type_supported(NAMESPACE_NET) && have_effective_cap(CAP_NET_ADMIN) > 0) { + r = setup_shareable_ns(runtime->shared->netns_storage_socket, CLONE_NEWNET); + if (ERRNO_IS_NEG_PRIVILEGE(r)) + log_exec_notice_errno(context, params, r, + "PrivateNetwork=yes is configured, but network namespace setup not permitted, proceeding without: %m"); + else if (r < 0) { + *exit_status = EXIT_NETWORK; + return log_exec_error_errno(context, params, r, "Failed to set up network namespacing: %m"); + } + } else if (context->network_namespace_path) { + *exit_status = EXIT_NETWORK; + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EOPNOTSUPP), + "NetworkNamespacePath= is not supported, refusing."); + } else + log_exec_notice(context, params, "PrivateNetwork=yes is configured, but the kernel does not support or we lack privileges for network namespace, proceeding without."); + } + + if (exec_needs_ipc_namespace(context) && runtime && runtime->shared && runtime->shared->ipcns_storage_socket[0] >= 0) { + + if (ns_type_supported(NAMESPACE_IPC)) { + r = setup_shareable_ns(runtime->shared->ipcns_storage_socket, CLONE_NEWIPC); + if (r == -EPERM) + log_exec_warning_errno(context, params, r, + "PrivateIPC=yes is configured, but IPC namespace setup failed, ignoring: %m"); + else if (r < 0) { + *exit_status = EXIT_NAMESPACE; + return log_exec_error_errno(context, params, r, "Failed to set up IPC namespacing: %m"); + } + } else if (context->ipc_namespace_path) { + *exit_status = EXIT_NAMESPACE; + return log_exec_error_errno(context, params, SYNTHETIC_ERRNO(EOPNOTSUPP), + "IPCNamespacePath= is not supported, refusing."); + } else + log_exec_warning(context, params, "PrivateIPC=yes is configured, but the kernel does not support IPC namespaces, ignoring."); + } + + if (needs_mount_namespace) { + _cleanup_free_ char *error_path = NULL; + + r = apply_mount_namespace(command->flags, context, params, runtime, memory_pressure_path, &error_path); + if (r < 0) { + *exit_status = EXIT_NAMESPACE; + return log_exec_error_errno(context, params, r, "Failed to set up mount namespacing%s%s: %m", + error_path ? ": " : "", strempty(error_path)); + } + } + + if (needs_sandboxing) { + r = apply_protect_hostname(context, params, exit_status); + if (r < 0) + return r; + } + + if (context->memory_ksm >= 0) + if (prctl(PR_SET_MEMORY_MERGE, context->memory_ksm) < 0) { + if (ERRNO_IS_NOT_SUPPORTED(errno)) + log_exec_debug_errno(context, + params, + errno, + "KSM support not available, ignoring."); + else { + *exit_status = EXIT_KSM; + return log_exec_error_errno(context, params, errno, "Failed to set KSM: %m"); + } + } + + /* Drop groups as early as possible. + * This needs to be done after PrivateDevices=yes setup as device nodes should be owned by the host's root. + * For non-root in a userns, devices will be owned by the user/group before the group change, and nobody. */ + if (needs_setuid) { + _cleanup_free_ gid_t *gids_to_enforce = NULL; + int ngids_to_enforce = 0; + + ngids_to_enforce = merge_gid_lists(supplementary_gids, + ngids, + gids_after_pam, + ngids_after_pam, + &gids_to_enforce); + if (ngids_to_enforce < 0) { + *exit_status = EXIT_GROUP; + return log_exec_error_errno(context, params, + ngids_to_enforce, + "Failed to merge group lists. Group membership might be incorrect: %m"); + } + + r = enforce_groups(gid, gids_to_enforce, ngids_to_enforce); + if (r < 0) { + *exit_status = EXIT_GROUP; + return log_exec_error_errno(context, params, r, "Changing group credentials failed: %m"); + } + } + + /* If the user namespace was not set up above, try to do it now. + * It's preferred to set up the user namespace later (after all other namespaces) so as not to be + * restricted by rules pertaining to combining user namespaces with other namespaces (e.g. in the + * case of mount namespaces being less privileged when the mount point list is copied from a + * different user namespace). */ + + if (needs_sandboxing && context->private_users && !userns_set_up) { + r = setup_private_users(saved_uid, saved_gid, uid, gid); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to set up user namespacing: %m"); + } + } + + /* Now that the mount namespace has been set up and privileges adjusted, let's look for the thing we + * shall execute. */ + + _cleanup_free_ char *executable = NULL; + _cleanup_close_ int executable_fd = -EBADF; + r = find_executable_full(command->path, /* root= */ NULL, context->exec_search_path, false, &executable, &executable_fd); + if (r < 0) { + if (r != -ENOMEM && (command->flags & EXEC_COMMAND_IGNORE_FAILURE)) { + log_exec_struct_errno(context, params, LOG_INFO, r, + "MESSAGE_ID=" SD_MESSAGE_SPAWN_FAILED_STR, + LOG_EXEC_INVOCATION_ID(params), + LOG_EXEC_MESSAGE(params, + "Executable %s missing, skipping: %m", + command->path), + "EXECUTABLE=%s", command->path); + *exit_status = EXIT_SUCCESS; + return 0; + } + + *exit_status = EXIT_EXEC; + return log_exec_struct_errno(context, params, LOG_INFO, r, + "MESSAGE_ID=" SD_MESSAGE_SPAWN_FAILED_STR, + LOG_EXEC_INVOCATION_ID(params), + LOG_EXEC_MESSAGE(params, + "Failed to locate executable %s: %m", + command->path), + "EXECUTABLE=%s", command->path); + } + + r = add_shifted_fd(keep_fds, ELEMENTSOF(keep_fds), &n_keep_fds, &executable_fd); + if (r < 0) { + *exit_status = EXIT_FDS; + return log_exec_error_errno(context, params, r, "Failed to collect shifted fd: %m"); + } + +#if HAVE_SELINUX + if (needs_sandboxing && use_selinux && params->selinux_context_net) { + int fd = -EBADF; + + if (socket_fd >= 0) + fd = socket_fd; + else if (params->n_socket_fds == 1) + /* If stdin is not connected to a socket but we are triggered by exactly one socket unit then we + * use context from that fd to compute the label. */ + fd = params->fds[0]; + + if (fd >= 0) { + r = mac_selinux_get_child_mls_label(fd, executable, context->selinux_context, &mac_selinux_context_net); + if (r < 0) { + if (!context->selinux_context_ignore) { + *exit_status = EXIT_SELINUX_CONTEXT; + return log_exec_error_errno(context, + params, + r, + "Failed to determine SELinux context: %m"); + } + log_exec_debug_errno(context, + params, + r, + "Failed to determine SELinux context, ignoring: %m"); + } + } + } +#endif + + /* We repeat the fd closing here, to make sure that nothing is leaked from the PAM modules. Note that + * we are more aggressive this time, since we don't need socket_fd and the netns and ipcns fds any + * more. We do keep exec_fd however, if we have it, since we need to keep it open until the final + * execve(). But first, close the remaining sockets in the context objects. */ + + exec_runtime_close(runtime); + exec_params_close(params); + + r = close_all_fds(keep_fds, n_keep_fds); + if (r >= 0) + r = shift_fds(params->fds, n_fds); + if (r >= 0) + r = flag_fds(params->fds, n_socket_fds, n_fds, context->non_blocking); + if (r < 0) { + *exit_status = EXIT_FDS; + return log_exec_error_errno(context, params, r, "Failed to adjust passed file descriptors: %m"); + } + + /* At this point, the fds we want to pass to the program are all ready and set up, with O_CLOEXEC turned off + * and at the right fd numbers. The are no other fds open, with one exception: the exec_fd if it is defined, + * and it has O_CLOEXEC set, after all we want it to be closed by the execve(), so that our parent knows we + * came this far. */ + + secure_bits = context->secure_bits; + + if (needs_sandboxing) { + uint64_t bset; + + /* Set the RTPRIO resource limit to 0, but only if nothing else was explicitly requested. + * (Note this is placed after the general resource limit initialization, see above, in order + * to take precedence.) */ + if (context->restrict_realtime && !context->rlimit[RLIMIT_RTPRIO]) { + if (setrlimit(RLIMIT_RTPRIO, &RLIMIT_MAKE_CONST(0)) < 0) { + *exit_status = EXIT_LIMITS; + return log_exec_error_errno(context, params, errno, "Failed to adjust RLIMIT_RTPRIO resource limit: %m"); + } + } + +#if ENABLE_SMACK + /* LSM Smack needs the capability CAP_MAC_ADMIN to change the current execution security context of the + * process. This is the latest place before dropping capabilities. Other MAC context are set later. */ + if (use_smack && context->smack_process_label) { + r = setup_smack(params, context, executable_fd); + if (r < 0 && !context->smack_process_label_ignore) { + *exit_status = EXIT_SMACK_PROCESS_LABEL; + return log_exec_error_errno(context, params, r, "Failed to set SMACK process label: %m"); + } + } +#endif + + bset = context->capability_bounding_set; + /* If the ambient caps hack is enabled (which means the kernel can't do them, and the user asked for + * our magic fallback), then let's add some extra caps, so that the service can drop privs of its own, + * instead of us doing that */ + if (needs_ambient_hack) + bset |= (UINT64_C(1) << CAP_SETPCAP) | + (UINT64_C(1) << CAP_SETUID) | + (UINT64_C(1) << CAP_SETGID); + +#if HAVE_SECCOMP + /* If the service has any form of a seccomp filter and it allows dropping privileges, we'll + * keep the needed privileges to apply it even if we're not root. */ + if (needs_setuid && + uid_is_valid(uid) && + context_has_seccomp(context) && + seccomp_allows_drop_privileges(context)) { + keep_seccomp_privileges = true; + + if (prctl(PR_SET_KEEPCAPS, 1) < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, errno, "Failed to enable keep capabilities flag: %m"); + } + + /* Save the current bounding set so we can restore it after applying the seccomp + * filter */ + saved_bset = bset; + bset |= (UINT64_C(1) << CAP_SYS_ADMIN) | + (UINT64_C(1) << CAP_SETPCAP); + } +#endif + + if (!cap_test_all(bset)) { + r = capability_bounding_set_drop(bset, /* right_now= */ false); + if (r < 0) { + *exit_status = EXIT_CAPABILITIES; + return log_exec_error_errno(context, params, r, "Failed to drop capabilities: %m"); + } + } + + /* Ambient capabilities are cleared during setresuid() (in enforce_user()) even with + * keep-caps set. + * + * To be able to raise the ambient capabilities after setresuid() they have to be added to + * the inherited set and keep caps has to be set (done in enforce_user()). After setresuid() + * the ambient capabilities can be raised as they are present in the permitted and + * inhertiable set. However it is possible that someone wants to set ambient capabilities + * without changing the user, so we also set the ambient capabilities here. + * + * The requested ambient capabilities are raised in the inheritable set if the second + * argument is true. */ + if (!needs_ambient_hack) { + r = capability_ambient_set_apply(capability_ambient_set, /* also_inherit= */ true); + if (r < 0) { + *exit_status = EXIT_CAPABILITIES; + return log_exec_error_errno(context, params, r, "Failed to apply ambient capabilities (before UID change): %m"); + } + } + } + + /* chroot to root directory first, before we lose the ability to chroot */ + r = apply_root_directory(context, params, runtime, needs_mount_namespace, exit_status); + if (r < 0) + return log_exec_error_errno(context, params, r, "Chrooting to the requested root directory failed: %m"); + + if (needs_setuid) { + if (uid_is_valid(uid)) { + r = enforce_user(context, uid, capability_ambient_set); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to change UID to " UID_FMT ": %m", uid); + } + + if (keep_seccomp_privileges) { + if (!FLAGS_SET(capability_ambient_set, (UINT64_C(1) << CAP_SETUID))) { + r = drop_capability(CAP_SETUID); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to drop CAP_SETUID: %m"); + } + } + + r = keep_capability(CAP_SYS_ADMIN); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to keep CAP_SYS_ADMIN: %m"); + } + + r = keep_capability(CAP_SETPCAP); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to keep CAP_SETPCAP: %m"); + } + } + + if (!needs_ambient_hack && capability_ambient_set != 0) { + + /* Raise the ambient capabilities after user change. */ + r = capability_ambient_set_apply(capability_ambient_set, /* also_inherit= */ false); + if (r < 0) { + *exit_status = EXIT_CAPABILITIES; + return log_exec_error_errno(context, params, r, "Failed to apply ambient capabilities (after UID change): %m"); + } + } + } + } + + /* Apply working directory here, because the working directory might be on NFS and only the user running + * this service might have the correct privilege to change to the working directory */ + r = apply_working_directory(context, params, runtime, home, exit_status); + if (r < 0) + return log_exec_error_errno(context, params, r, "Changing to the requested working directory failed: %m"); + + if (needs_sandboxing) { + /* Apply other MAC contexts late, but before seccomp syscall filtering, as those should really be last to + * influence our own codepaths as little as possible. Moreover, applying MAC contexts usually requires + * syscalls that are subject to seccomp filtering, hence should probably be applied before the syscalls + * are restricted. */ + +#if HAVE_SELINUX + if (use_selinux) { + char *exec_context = mac_selinux_context_net ?: context->selinux_context; + + if (exec_context) { + r = setexeccon(exec_context); + if (r < 0) { + if (!context->selinux_context_ignore) { + *exit_status = EXIT_SELINUX_CONTEXT; + return log_exec_error_errno(context, params, r, "Failed to change SELinux context to %s: %m", exec_context); + } + log_exec_debug_errno(context, + params, + r, + "Failed to change SELinux context to %s, ignoring: %m", + exec_context); + } + } + } +#endif + +#if HAVE_APPARMOR + if (use_apparmor && context->apparmor_profile) { + r = aa_change_onexec(context->apparmor_profile); + if (r < 0 && !context->apparmor_profile_ignore) { + *exit_status = EXIT_APPARMOR_PROFILE; + return log_exec_error_errno(context, + params, + errno, + "Failed to prepare AppArmor profile change to %s: %m", + context->apparmor_profile); + } + } +#endif + + /* PR_GET_SECUREBITS is not privileged, while PR_SET_SECUREBITS is. So to suppress potential + * EPERMs we'll try not to call PR_SET_SECUREBITS unless necessary. Setting securebits + * requires CAP_SETPCAP. */ + if (prctl(PR_GET_SECUREBITS) != secure_bits) { + /* CAP_SETPCAP is required to set securebits. This capability is raised into the + * effective set here. + * + * The effective set is overwritten during execve() with the following values: + * + * - ambient set (for non-root processes) + * + * - (inheritable | bounding) set for root processes) + * + * Hence there is no security impact to raise it in the effective set before execve + */ + r = capability_gain_cap_setpcap(/* return_caps= */ NULL); + if (r < 0) { + *exit_status = EXIT_CAPABILITIES; + return log_exec_error_errno(context, params, r, "Failed to gain CAP_SETPCAP for setting secure bits"); + } + if (prctl(PR_SET_SECUREBITS, secure_bits) < 0) { + *exit_status = EXIT_SECUREBITS; + return log_exec_error_errno(context, params, errno, "Failed to set process secure bits: %m"); + } + } + + if (context_has_no_new_privileges(context)) + if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) { + *exit_status = EXIT_NO_NEW_PRIVILEGES; + return log_exec_error_errno(context, params, errno, "Failed to disable new privileges: %m"); + } + +#if HAVE_SECCOMP + r = apply_address_families(context, params); + if (r < 0) { + *exit_status = EXIT_ADDRESS_FAMILIES; + return log_exec_error_errno(context, params, r, "Failed to restrict address families: %m"); + } + + r = apply_memory_deny_write_execute(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to disable writing to executable memory: %m"); + } + + r = apply_restrict_realtime(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply realtime restrictions: %m"); + } + + r = apply_restrict_suid_sgid(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply SUID/SGID restrictions: %m"); + } + + r = apply_restrict_namespaces(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply namespace restrictions: %m"); + } + + r = apply_protect_sysctl(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply sysctl restrictions: %m"); + } + + r = apply_protect_kernel_modules(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply module loading restrictions: %m"); + } + + r = apply_protect_kernel_logs(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply kernel log restrictions: %m"); + } + + r = apply_protect_clock(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply clock restrictions: %m"); + } + + r = apply_private_devices(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to set up private devices: %m"); + } + + r = apply_syscall_archs(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply syscall architecture restrictions: %m"); + } + + r = apply_lock_personality(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to lock personalities: %m"); + } + + r = apply_syscall_log(context, params); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply system call log filters: %m"); + } +#endif + +#if HAVE_LIBBPF + r = apply_restrict_filesystems(context, params); + if (r < 0) { + *exit_status = EXIT_BPF; + return log_exec_error_errno(context, params, r, "Failed to restrict filesystems: %m"); + } +#endif + +#if HAVE_SECCOMP + /* This really should remain as close to the execve() as possible, to make sure our own code is affected + * by the filter as little as possible. */ + r = apply_syscall_filter(context, params, needs_ambient_hack); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return log_exec_error_errno(context, params, r, "Failed to apply system call filters: %m"); + } + + if (keep_seccomp_privileges) { + /* Restore the capability bounding set with what's expected from the service + the + * ambient capabilities hack */ + if (!cap_test_all(saved_bset)) { + r = capability_bounding_set_drop(saved_bset, /* right_now= */ false); + if (r < 0) { + *exit_status = EXIT_CAPABILITIES; + return log_exec_error_errno(context, params, r, "Failed to drop bset capabilities: %m"); + } + } + + /* Only drop CAP_SYS_ADMIN if it's not in the bounding set, otherwise we'll break + * applications that use it. */ + if (!FLAGS_SET(saved_bset, (UINT64_C(1) << CAP_SYS_ADMIN))) { + r = drop_capability(CAP_SYS_ADMIN); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to drop CAP_SYS_ADMIN: %m"); + } + } + + /* Only drop CAP_SETPCAP if it's not in the bounding set, otherwise we'll break + * applications that use it. */ + if (!FLAGS_SET(saved_bset, (UINT64_C(1) << CAP_SETPCAP))) { + r = drop_capability(CAP_SETPCAP); + if (r < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, r, "Failed to drop CAP_SETPCAP: %m"); + } + } + + if (prctl(PR_SET_KEEPCAPS, 0) < 0) { + *exit_status = EXIT_USER; + return log_exec_error_errno(context, params, errno, "Failed to drop keep capabilities flag: %m"); + } + } +#endif + + } + + if (!strv_isempty(context->unset_environment)) { + char **ee = NULL; + + ee = strv_env_delete(accum_env, 1, context->unset_environment); + if (!ee) { + *exit_status = EXIT_MEMORY; + return log_oom(); + } + + strv_free_and_replace(accum_env, ee); + } + + if (!FLAGS_SET(command->flags, EXEC_COMMAND_NO_ENV_EXPAND)) { + _cleanup_strv_free_ char **unset_variables = NULL, **bad_variables = NULL; + + r = replace_env_argv(command->argv, accum_env, &replaced_argv, &unset_variables, &bad_variables); + if (r < 0) { + *exit_status = EXIT_MEMORY; + return log_exec_error_errno(context, + params, + r, + "Failed to replace environment variables: %m"); + } + final_argv = replaced_argv; + + if (!strv_isempty(unset_variables)) { + _cleanup_free_ char *ju = strv_join(unset_variables, ", "); + log_exec_warning(context, + params, + "Referenced but unset environment variable evaluates to an empty string: %s", + strna(ju)); + } + + if (!strv_isempty(bad_variables)) { + _cleanup_free_ char *jb = strv_join(bad_variables, ", "); + log_exec_warning(context, + params, + "Invalid environment variable name evaluates to an empty string: %s", + strna(jb)); + } + } else + final_argv = command->argv; + + log_command_line(context, params, "Executing", executable, final_argv); + + if (params->exec_fd >= 0) { + uint8_t hot = 1; + + /* We have finished with all our initializations. Let's now let the manager know that. From this point + * on, if the manager sees POLLHUP on the exec_fd, then execve() was successful. */ + + if (write(params->exec_fd, &hot, sizeof(hot)) < 0) { + *exit_status = EXIT_EXEC; + return log_exec_error_errno(context, params, errno, "Failed to enable exec_fd: %m"); + } + } + + r = fexecve_or_execve(executable_fd, executable, final_argv, accum_env); + + if (params->exec_fd >= 0) { + uint8_t hot = 0; + + /* The execve() failed. This means the exec_fd is still open. Which means we need to tell the manager + * that POLLHUP on it no longer means execve() succeeded. */ + + if (write(params->exec_fd, &hot, sizeof(hot)) < 0) { + *exit_status = EXIT_EXEC; + return log_exec_error_errno(context, params, errno, "Failed to disable exec_fd: %m"); + } + } + + *exit_status = EXIT_EXEC; + return log_exec_error_errno(context, params, r, "Failed to execute %s: %m", executable); +} |