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-rw-r--r--src/exec_pty.c1377
1 files changed, 1377 insertions, 0 deletions
diff --git a/src/exec_pty.c b/src/exec_pty.c
new file mode 100644
index 0000000..9a8ddfa
--- /dev/null
+++ b/src/exec_pty.c
@@ -0,0 +1,1377 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2009-2023 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <sys/ioctl.h>
+
+#if defined(HAVE_STDINT_H)
+# include <stdint.h>
+#elif defined(HAVE_INTTYPES_H)
+# include <inttypes.h>
+#endif
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <termios.h> /* for struct winsize on HP-UX */
+
+#include "sudo.h"
+#include "sudo_exec.h"
+#include "sudo_plugin.h"
+#include "sudo_plugin_int.h"
+
+/* Tail queue of messages to send to the monitor. */
+struct monitor_message {
+ TAILQ_ENTRY(monitor_message) entries;
+ struct command_status cstat;
+};
+TAILQ_HEAD(monitor_message_list, monitor_message);
+static struct monitor_message_list monitor_messages =
+ TAILQ_HEAD_INITIALIZER(monitor_messages);
+
+static char ptyname[PATH_MAX];
+static bool foreground, pipeline;
+static const char *utmp_user;
+
+static void sync_ttysize(struct exec_closure *ec);
+static pid_t check_foreground(struct exec_closure *ec);
+static void schedule_signal(struct exec_closure *ec, int signo);
+
+/*
+ * Cleanup hook for sudo_fatal()/sudo_fatalx()
+ */
+void
+pty_cleanup(void)
+{
+ debug_decl(cleanup, SUDO_DEBUG_EXEC);
+
+ if (ttymode != TERM_COOKED) {
+ if (!sudo_term_restore(io_fds[SFD_USERTTY], false))
+ sudo_warn("%s", U_("unable to restore terminal settings"));
+ }
+ if (utmp_user != NULL)
+ utmp_logout(ptyname, 0);
+
+ debug_return;
+}
+
+/*
+ * Allocate a pty if /dev/tty is a tty.
+ * Fills in io_fds[SFD_USERTTY], io_fds[SFD_LEADER], io_fds[SFD_FOLLOWER]
+ * and ptyname globals.
+ */
+static bool
+pty_setup(struct command_details *details, const char *tty)
+{
+ debug_decl(pty_setup, SUDO_DEBUG_EXEC);
+
+ io_fds[SFD_USERTTY] = open(_PATH_TTY, O_RDWR);
+ if (io_fds[SFD_USERTTY] == -1) {
+ sudo_debug_printf(SUDO_DEBUG_INFO, "%s: no %s, not allocating a pty",
+ __func__, _PATH_TTY);
+ debug_return_bool(false);
+ }
+
+ if (!get_pty(&io_fds[SFD_LEADER], &io_fds[SFD_FOLLOWER],
+ ptyname, sizeof(ptyname), details->cred.euid))
+ sudo_fatal("%s", U_("unable to allocate pty"));
+
+ /* Update tty name in command details (used by SELinux and AIX). */
+ details->tty = ptyname;
+
+ /* Add entry to utmp/utmpx? */
+ if (ISSET(details->flags, CD_SET_UTMP)) {
+ utmp_user =
+ details->utmp_user ? details->utmp_user : user_details.username;
+ utmp_login(tty, ptyname, io_fds[SFD_FOLLOWER], utmp_user);
+ }
+
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "%s: %s fd %d, pty leader fd %d, pty follower fd %d",
+ __func__, _PATH_TTY, io_fds[SFD_USERTTY], io_fds[SFD_LEADER],
+ io_fds[SFD_FOLLOWER]);
+
+ debug_return_bool(true);
+}
+
+/*
+ * Make the tty follower the controlling tty.
+ * This is only used by the monitor but ptyname[] is static.
+ */
+int
+pty_make_controlling(void)
+{
+ if (io_fds[SFD_FOLLOWER] != -1) {
+#ifdef TIOCSCTTY
+ if (ioctl(io_fds[SFD_FOLLOWER], TIOCSCTTY, NULL) != 0)
+ return -1;
+#else
+ /* Set controlling tty by reopening pty follower. */
+ int fd = open(ptyname, O_RDWR);
+ if (fd == -1)
+ return -1;
+ close(fd);
+#endif
+ }
+ return 0;
+}
+
+/*
+ * Check whether we are running in the foregroup.
+ * Updates the foreground global and updates the window size.
+ * Returns 0 if there is no tty, the foreground process group ID
+ * on success, or -1 on failure (tty revoked).
+ */
+static pid_t
+check_foreground(struct exec_closure *ec)
+{
+ int ret = 0;
+ debug_decl(check_foreground, SUDO_DEBUG_EXEC);
+
+ if (io_fds[SFD_USERTTY] != -1) {
+ if ((ret = tcgetpgrp(io_fds[SFD_USERTTY])) != -1) {
+ foreground = ret == ec->ppgrp;
+
+ /* Also check for window size changes. */
+ sync_ttysize(ec);
+ }
+ }
+ debug_return_int(ret);
+}
+
+/*
+ * Suspend sudo if the underlying command is suspended.
+ * Returns SIGCONT_FG if the command should be resumed in the
+ * foreground or SIGCONT_BG if it is a background process.
+ */
+static int
+suspend_sudo_pty(struct exec_closure *ec, int signo)
+{
+ char signame[SIG2STR_MAX];
+ struct sigaction sa, osa;
+ int ret = 0;
+ debug_decl(suspend_sudo_pty, SUDO_DEBUG_EXEC);
+
+ switch (signo) {
+ case SIGTTOU:
+ case SIGTTIN:
+ /*
+ * If sudo is already the foreground process, just resume the command
+ * in the foreground. If not, we'll suspend sudo and resume later.
+ */
+ if (!foreground) {
+ if (check_foreground(ec) == -1) {
+ /* User's tty was revoked. */
+ break;
+ }
+ }
+ if (foreground) {
+ if (ttymode != TERM_RAW) {
+ if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
+ ttymode = TERM_RAW;
+ }
+ ret = SIGCONT_FG; /* resume command in foreground */
+ break;
+ }
+ FALLTHROUGH;
+ case SIGSTOP:
+ case SIGTSTP:
+ /* Flush any remaining output and deschedule I/O events. */
+ del_io_events(true);
+
+ /* Restore original tty mode before suspending. */
+ if (ttymode != TERM_COOKED) {
+ if (!sudo_term_restore(io_fds[SFD_USERTTY], false))
+ sudo_warn("%s", U_("unable to restore terminal settings"));
+ }
+
+ /* Log the suspend event. */
+ log_suspend(ec, signo);
+
+ if (sig2str(signo, signame) == -1)
+ (void)snprintf(signame, sizeof(signame), "%d", signo);
+
+ /* Suspend self and continue command when we resume. */
+ if (signo != SIGSTOP) {
+ memset(&sa, 0, sizeof(sa));
+ sigemptyset(&sa.sa_mask);
+ sa.sa_flags = SA_RESTART;
+ sa.sa_handler = SIG_DFL;
+ if (sudo_sigaction(signo, &sa, &osa) != 0)
+ sudo_warn(U_("unable to set handler for signal %d"), signo);
+ }
+ /*
+ * We stop sudo's process group, even if sudo is not the process
+ * group leader. If we only send the signal to sudo itself,
+ * the shell will not notice if it is not in monitor mode.
+ * This can happen when sudo is run from a shell script, for
+ * example. In this case we need to signal the shell itself.
+ * If the process group leader is no longer present, we must kill
+ * the command since there will be no one to resume us.
+ */
+ sudo_debug_printf(SUDO_DEBUG_INFO, "killpg(%d, SIG%s) [parent]",
+ (int)ec->ppgrp, signame);
+ if ((ec->ppgrp != ec->sudo_pid && kill(ec->ppgrp, 0) == -1) ||
+ killpg(ec->ppgrp, signo) == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR,
+ "no parent to suspend, terminating command.");
+ terminate_command(ec->cmnd_pid, true);
+ ec->cmnd_pid = -1;
+ break;
+ }
+
+ /* Log the resume event. */
+ log_suspend(ec, SIGCONT);
+
+ /* Check foreground/background status on resume. */
+ if (check_foreground(ec) == -1) {
+ /* User's tty was revoked. */
+ break;
+ }
+
+ /*
+ * We always resume the command in the foreground if sudo itself
+ * is the foreground process. This helps work around poorly behaved
+ * programs that catch SIGTTOU/SIGTTIN but suspend themselves with
+ * SIGSTOP. At worst, sudo will go into the background but upon
+ * resume the command will be runnable. Otherwise, we can get into
+ * a situation where the command will immediately suspend itself.
+ */
+ sudo_debug_printf(SUDO_DEBUG_INFO, "parent is in %s, ttymode %d -> %d",
+ foreground ? "foreground" : "background", ttymode,
+ foreground ? TERM_RAW : TERM_COOKED);
+
+ if (foreground) {
+ /* Foreground process, set tty to raw mode. */
+ if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
+ ttymode = TERM_RAW;
+ } else {
+ /* Background process, no access to tty. */
+ ttymode = TERM_COOKED;
+ }
+
+ if (signo != SIGSTOP) {
+ if (sudo_sigaction(signo, &osa, NULL) != 0)
+ sudo_warn(U_("unable to restore handler for signal %d"), signo);
+ }
+
+ ret = ttymode == TERM_RAW ? SIGCONT_FG : SIGCONT_BG;
+ break;
+ }
+
+ debug_return_int(ret);
+}
+
+/*
+ * SIGTTIN signal handler for read_callback that just sets a flag.
+ */
+static volatile sig_atomic_t got_sigttin;
+
+static void
+sigttin(int signo)
+{
+ got_sigttin = 1;
+}
+
+/*
+ * Read an iobuf that is ready.
+ */
+static void
+read_callback(int fd, int what, void *v)
+{
+ struct io_buffer *iob = v;
+ struct sudo_event_base *evbase = sudo_ev_get_base(iob->revent);
+ struct sigaction sa, osa;
+ int saved_errno;
+ ssize_t n;
+ debug_decl(read_callback, SUDO_DEBUG_EXEC);
+
+ /*
+ * We ignore SIGTTIN by default but we need to handle it when reading
+ * from the terminal. A signal event won't work here because the
+ * read() would be restarted, preventing the callback from running.
+ */
+ memset(&sa, 0, sizeof(sa));
+ sigemptyset(&sa.sa_mask);
+ sa.sa_handler = sigttin;
+ got_sigttin = 0;
+ sigaction(SIGTTIN, &sa, &osa);
+ n = read(fd, iob->buf + iob->len, sizeof(iob->buf) - iob->len);
+ saved_errno = errno;
+ sigaction(SIGTTIN, &osa, NULL);
+ errno = saved_errno;
+
+ switch (n) {
+ case -1:
+ if (got_sigttin) {
+ /* Schedule SIGTTIN to be forwarded to the command. */
+ schedule_signal(iob->ec, SIGTTIN);
+ }
+ if (errno == EAGAIN || errno == EINTR) {
+ /* Not an error, retry later. */
+ break;
+ }
+ /* Treat read error as fatal and close the fd. */
+ sudo_debug_printf(SUDO_DEBUG_ERROR,
+ "error reading fd %d: %s", fd, strerror(errno));
+ FALLTHROUGH;
+ case 0:
+ /* got EOF or pty has gone away */
+ if (n == 0) {
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "read EOF from fd %d", fd);
+ }
+ safe_close(fd);
+ ev_free_by_fd(evbase, fd);
+ /* If writer already consumed the buffer, close it too. */
+ if (iob->wevent != NULL && iob->off == iob->len) {
+ safe_close(sudo_ev_get_fd(iob->wevent));
+ ev_free_by_fd(evbase, sudo_ev_get_fd(iob->wevent));
+ iob->off = iob->len = 0;
+ }
+ break;
+ default:
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "read %zd bytes from fd %d", n, fd);
+ if (!iob->action(iob->buf + iob->len, n, iob)) {
+ terminate_command(iob->ec->cmnd_pid, true);
+ iob->ec->cmnd_pid = -1;
+ }
+ iob->len += n;
+ /* Disable reader if buffer is full. */
+ if (iob->len == sizeof(iob->buf))
+ sudo_ev_del(evbase, iob->revent);
+ /* Enable writer now that there is new data in the buffer. */
+ if (iob->wevent != NULL) {
+ if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+ }
+ break;
+ }
+
+ debug_return;
+}
+
+/*
+ * SIGTTOU signal handler for write_callback that just sets a flag.
+ */
+static volatile sig_atomic_t got_sigttou;
+
+static void
+sigttou(int signo)
+{
+ got_sigttou = 1;
+}
+
+/*
+ * Write an iobuf that is ready.
+ */
+static void
+write_callback(int fd, int what, void *v)
+{
+ struct io_buffer *iob = v;
+ struct sudo_event_base *evbase = sudo_ev_get_base(iob->wevent);
+ struct sigaction sa, osa;
+ int saved_errno;
+ ssize_t n;
+ debug_decl(write_callback, SUDO_DEBUG_EXEC);
+
+ /*
+ * We ignore SIGTTOU by default but we need to handle it when writing
+ * to the terminal. A signal event won't work here because the
+ * write() would be restarted, preventing the callback from running.
+ */
+ memset(&sa, 0, sizeof(sa));
+ sigemptyset(&sa.sa_mask);
+ sa.sa_handler = sigttou;
+ got_sigttou = 0;
+ sigaction(SIGTTOU, &sa, &osa);
+ n = write(fd, iob->buf + iob->off, iob->len - iob->off);
+ saved_errno = errno;
+ sigaction(SIGTTOU, &osa, NULL);
+ errno = saved_errno;
+
+ if (n == -1) {
+ switch (errno) {
+ case EPIPE:
+ case ENXIO:
+ case EIO:
+ case EBADF:
+ /* other end of pipe closed or pty revoked */
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "unable to write %d bytes to fd %d",
+ iob->len - iob->off, fd);
+ /* Close reader if there is one. */
+ if (iob->revent != NULL) {
+ safe_close(sudo_ev_get_fd(iob->revent));
+ ev_free_by_fd(evbase, sudo_ev_get_fd(iob->revent));
+ }
+ safe_close(fd);
+ ev_free_by_fd(evbase, fd);
+ break;
+ case EINTR:
+ if (got_sigttou) {
+ /* Schedule SIGTTOU to be forwarded to the command. */
+ schedule_signal(iob->ec, SIGTTOU);
+ }
+ FALLTHROUGH;
+ case EAGAIN:
+ /* Not an error, retry later. */
+ break;
+ default:
+ /* XXX - need a way to distinguish non-exec error. */
+ iob->ec->cstat->type = CMD_ERRNO;
+ iob->ec->cstat->val = errno;
+ sudo_debug_printf(SUDO_DEBUG_ERROR,
+ "error writing fd %d: %s", fd, strerror(errno));
+ sudo_ev_loopbreak(evbase);
+ break;
+ }
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "wrote %zd bytes to fd %d", n, fd);
+ iob->off += n;
+ /* Disable writer and reset the buffer if fully consumed. */
+ if (iob->off == iob->len) {
+ iob->off = iob->len = 0;
+ sudo_ev_del(evbase, iob->wevent);
+ /* Forward the EOF from reader to writer. */
+ if (iob->revent == NULL) {
+ safe_close(fd);
+ ev_free_by_fd(evbase, fd);
+ }
+ }
+ /*
+ * Enable reader if buffer is not full but avoid reading /dev/tty
+ * if not in raw mode or the command is no longer running.
+ */
+ if (iob->revent != NULL && iob->len != sizeof(iob->buf)) {
+ if (!USERTTY_EVENT(iob->revent) ||
+ (ttymode == TERM_RAW && iob->ec->cmnd_pid != -1)) {
+ if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+ }
+ }
+ }
+
+ debug_return;
+}
+
+/*
+ * We already closed the follower so reads from the leader will not block.
+ */
+static void
+pty_finish(struct exec_closure *ec, struct command_status *cstat)
+{
+ int flags;
+ debug_decl(pty_finish, SUDO_DEBUG_EXEC);
+
+ /* Flush any remaining output (the plugin already got it) and free bufs. */
+ if (io_fds[SFD_USERTTY] != -1) {
+ flags = fcntl(io_fds[SFD_USERTTY], F_GETFL, 0);
+ if (flags != -1 && ISSET(flags, O_NONBLOCK)) {
+ CLR(flags, O_NONBLOCK);
+ (void) fcntl(io_fds[SFD_USERTTY], F_SETFL, flags);
+ }
+ }
+ del_io_events(false);
+ free_io_bufs();
+
+ /* Restore terminal settings. */
+ if (ttymode != TERM_COOKED) {
+ /* Only restore the terminal if sudo is the foreground process. */
+ const pid_t tcpgrp = tcgetpgrp(io_fds[SFD_USERTTY]);
+ if (tcpgrp == ec->ppgrp) {
+ if (!sudo_term_restore(io_fds[SFD_USERTTY], false))
+ sudo_warn("%s", U_("unable to restore terminal settings"));
+ }
+ }
+
+ /* Update utmp */
+ if (utmp_user != NULL)
+ utmp_logout(ptyname, cstat->type == CMD_WSTATUS ? cstat->val : 0);
+
+ debug_return;
+}
+
+/*
+ * Send command status to the monitor (signal or window size change).
+ */
+static void
+send_command_status(struct exec_closure *ec, int type, int val)
+{
+ struct monitor_message *msg;
+ debug_decl(send_command, SUDO_DEBUG_EXEC);
+
+ if ((msg = calloc(1, sizeof(*msg))) == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ msg->cstat.type = type;
+ msg->cstat.val = val;
+ TAILQ_INSERT_TAIL(&monitor_messages, msg, entries);
+
+ if (sudo_ev_add(ec->evbase, ec->fwdchannel_event, NULL, true) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ /* Restart event loop to send the command immediately. */
+ sudo_ev_loopcontinue(ec->evbase);
+
+ debug_return;
+}
+
+/*
+ * Schedule a signal to be forwarded.
+ */
+static void
+schedule_signal(struct exec_closure *ec, int signo)
+{
+ char signame[SIG2STR_MAX];
+ debug_decl(schedule_signal, SUDO_DEBUG_EXEC);
+
+ if (signo == 0)
+ debug_return;
+
+ if (signo == SIGCONT_FG)
+ strlcpy(signame, "CONT_FG", sizeof(signame));
+ else if (signo == SIGCONT_BG)
+ strlcpy(signame, "CONT_BG", sizeof(signame));
+ else if (sig2str(signo, signame) == -1)
+ (void)snprintf(signame, sizeof(signame), "%d", signo);
+ sudo_debug_printf(SUDO_DEBUG_DIAG, "scheduled SIG%s for command", signame);
+
+ send_command_status(ec, CMD_SIGNO, signo);
+
+ debug_return;
+}
+
+/*
+ * Free any remaining monitor messages in the queue.
+ */
+static void
+flush_monitor_messages(void)
+{
+ struct monitor_message *msg;
+ debug_decl(flush_monitor_messages, SUDO_DEBUG_EXEC);
+
+ while ((msg = TAILQ_FIRST(&monitor_messages)) != NULL) {
+ TAILQ_REMOVE(&monitor_messages, msg, entries);
+ free(msg);
+ }
+
+ debug_return;
+}
+
+static void
+backchannel_cb(int fd, int what, void *v)
+{
+ struct exec_closure *ec = v;
+ struct command_status cstat;
+ ssize_t nread;
+ debug_decl(backchannel_cb, SUDO_DEBUG_EXEC);
+
+ /*
+ * Read command status from the monitor.
+ * Note that the backchannel is a *blocking* socket.
+ */
+ nread = recv(fd, &cstat, sizeof(cstat), MSG_WAITALL);
+ switch (nread) {
+ case -1:
+ switch (errno) {
+ case EINTR:
+ case EAGAIN:
+ /* Nothing ready. */
+ break;
+ default:
+ if (ec->cstat->val == CMD_INVALID) {
+ ec->cstat->type = CMD_ERRNO;
+ ec->cstat->val = errno;
+ sudo_debug_printf(SUDO_DEBUG_ERROR,
+ "%s: failed to read command status: %s",
+ __func__, strerror(errno));
+ sudo_ev_loopbreak(ec->evbase);
+ }
+ break;
+ }
+ break;
+ case 0:
+ /* EOF, monitor exited or was killed. */
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "EOF on backchannel, monitor dead?");
+ if (ec->cstat->type == CMD_INVALID) {
+ /* XXX - need new CMD_ type for monitor errors. */
+ ec->cstat->type = CMD_ERRNO;
+ ec->cstat->val = ECONNRESET;
+ }
+ sudo_ev_loopexit(ec->evbase);
+ break;
+ case sizeof(cstat):
+ /* Check command status. */
+ switch (cstat.type) {
+ case CMD_PID:
+ ec->cmnd_pid = cstat.val;
+ sudo_debug_printf(SUDO_DEBUG_INFO, "executed %s, pid %d",
+ ec->details->command, (int)ec->cmnd_pid);
+ if (ISSET(ec->details->flags, CD_USE_PTRACE)) {
+ /* Try to seize control of the command using ptrace(2). */
+ int rc = exec_ptrace_seize(ec->cmnd_pid);
+ if (rc == 0) {
+ /* There is another tracer present. */
+ CLR(ec->details->flags, CD_INTERCEPT|CD_LOG_SUBCMDS|CD_USE_PTRACE);
+ } else if (rc == -1) {
+ if (ec->cstat->type == CMD_INVALID) {
+ ec->cstat->type = CMD_ERRNO;
+ ec->cstat->val = errno;
+ }
+ sudo_ev_loopbreak(ec->evbase);
+ }
+ }
+ break;
+ case CMD_WSTATUS:
+ if (WIFSTOPPED(cstat.val)) {
+ int signo;
+
+ /* Suspend parent and tell monitor how to resume on return. */
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "command stopped, suspending parent");
+ signo = suspend_sudo_pty(ec, WSTOPSIG(cstat.val));
+ schedule_signal(ec, signo);
+ /* Re-enable I/O events */
+ add_io_events(ec->evbase);
+ } else {
+ /* Command exited or was killed, either way we are done. */
+ sudo_debug_printf(SUDO_DEBUG_INFO, "command exited or was killed");
+ sudo_ev_loopexit(ec->evbase);
+ *ec->cstat = cstat;
+ }
+ break;
+ case CMD_ERRNO:
+ /* Monitor was unable to execute command or broken pipe. */
+ sudo_debug_printf(SUDO_DEBUG_INFO, "errno from monitor: %s",
+ strerror(cstat.val));
+ sudo_ev_loopbreak(ec->evbase);
+ *ec->cstat = cstat;
+ break;
+ }
+ /* Keep reading command status messages until EAGAIN or EOF. */
+ break;
+ default:
+ /* Short read, should not happen. */
+ if (ec->cstat->val == CMD_INVALID) {
+ ec->cstat->type = CMD_ERRNO;
+ ec->cstat->val = EIO;
+ sudo_debug_printf(SUDO_DEBUG_ERROR,
+ "%s: failed to read command status: short read", __func__);
+ sudo_ev_loopbreak(ec->evbase);
+ }
+ break;
+ }
+ debug_return;
+}
+
+/*
+ * Handle changes to the monitors's status (SIGCHLD).
+ */
+static void
+handle_sigchld_pty(struct exec_closure *ec)
+{
+ int n, status;
+ pid_t pid;
+ debug_decl(handle_sigchld_pty, SUDO_DEBUG_EXEC);
+
+ /* There may be multiple children in intercept mode. */
+ for (;;) {
+ do {
+ pid = waitpid(-1, &status, __WALL|WUNTRACED|WNOHANG);
+ } while (pid == -1 && errno == EINTR);
+ switch (pid) {
+ case -1:
+ if (errno != ECHILD) {
+ sudo_warn(U_("%s: %s"), __func__, "waitpid");
+ debug_return;
+ }
+ FALLTHROUGH;
+ case 0:
+ /* Nothing left to wait for. */
+ debug_return;
+ }
+
+ if (WIFEXITED(status)) {
+ sudo_debug_printf(SUDO_DEBUG_INFO, "%s: process %d exited: %d",
+ __func__, (int)pid, WEXITSTATUS(status));
+ if (pid == ec->monitor_pid)
+ ec->monitor_pid = -1;
+ } else if (WIFSIGNALED(status)) {
+ char signame[SIG2STR_MAX];
+
+ if (sig2str(WTERMSIG(status), signame) == -1)
+ (void)snprintf(signame, sizeof(signame), "%d", WTERMSIG(status));
+ sudo_debug_printf(SUDO_DEBUG_INFO, "%s: process %d killed, SIG%s",
+ __func__, (int)pid, signame);
+ if (pid == ec->monitor_pid)
+ ec->monitor_pid = -1;
+ } else if (WIFSTOPPED(status)) {
+ if (pid != ec->monitor_pid) {
+ if (ISSET(ec->details->flags, CD_USE_PTRACE))
+ exec_ptrace_stopped(pid, status, ec->intercept);
+ continue;
+ }
+
+ /*
+ * If the monitor dies we get notified via backchannel_cb().
+ * If it was stopped, we should stop too (the command keeps
+ * running in its pty) and continue it when we come back.
+ */
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "monitor stopped, suspending sudo");
+ n = suspend_sudo_pty(ec, WSTOPSIG(status));
+ kill(pid, SIGCONT);
+ schedule_signal(ec, n);
+ /* Re-enable I/O events */
+ add_io_events(ec->evbase);
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_WARN,
+ "%s: unexpected wait status 0x%x for process (%d)",
+ __func__, status, (int)pid);
+ }
+ }
+}
+
+/* Signal callback */
+static void
+signal_cb_pty(int signo, int what, void *v)
+{
+ struct sudo_ev_siginfo_container *sc = v;
+ struct exec_closure *ec = sc->closure;
+ char signame[SIG2STR_MAX];
+ debug_decl(signal_cb_pty, SUDO_DEBUG_EXEC);
+
+ if (ec->monitor_pid == -1)
+ debug_return;
+
+ if (sig2str(signo, signame) == -1)
+ (void)snprintf(signame, sizeof(signame), "%d", signo);
+ sudo_debug_printf(SUDO_DEBUG_DIAG,
+ "%s: evbase %p, monitor: %d, signo %s(%d), cstat %p", __func__,
+ ec->evbase, (int)ec->monitor_pid, signame, signo, ec->cstat);
+
+ switch (signo) {
+ case SIGCHLD:
+ handle_sigchld_pty(ec);
+ break;
+ case SIGWINCH:
+ sync_ttysize(ec);
+ break;
+ default:
+ /*
+ * Do not forward signals sent by the command itself or a member of the
+ * command's process group (but only when either sudo or the command is
+ * the process group leader). We don't want the command to indirectly
+ * kill itself. For example, this can happen with some versions of
+ * reboot that call kill(-1, SIGTERM) to kill all other processes.
+ */
+ if (USER_SIGNALED(sc->siginfo) && sc->siginfo->si_pid != 0) {
+ pid_t si_pgrp;
+
+ if (sc->siginfo->si_pid == ec->cmnd_pid)
+ debug_return;
+ si_pgrp = getpgid(sc->siginfo->si_pid);
+ if (si_pgrp != -1) {
+ if (si_pgrp == ec->cmnd_pid || si_pgrp == ec->sudo_pid)
+ debug_return;
+ }
+ }
+ /* Schedule signal to be forwarded to the command. */
+ schedule_signal(ec, signo);
+ break;
+ }
+
+ debug_return;
+}
+
+/*
+ * Forward signals in monitor_messages to the monitor so it can
+ * deliver them to the command.
+ */
+static void
+fwdchannel_cb(int sock, int what, void *v)
+{
+ struct exec_closure *ec = v;
+ char signame[SIG2STR_MAX];
+ struct monitor_message *msg;
+ ssize_t nsent;
+ debug_decl(fwdchannel_cb, SUDO_DEBUG_EXEC);
+
+ while ((msg = TAILQ_FIRST(&monitor_messages)) != NULL) {
+ switch (msg->cstat.type) {
+ case CMD_SIGNO:
+ if (msg->cstat.val == SIGCONT_FG)
+ strlcpy(signame, "CONT_FG", sizeof(signame));
+ else if (msg->cstat.val == SIGCONT_BG)
+ strlcpy(signame, "CONT_BG", sizeof(signame));
+ else if (sig2str(msg->cstat.val, signame) == -1)
+ (void)snprintf(signame, sizeof(signame), "%d", msg->cstat.val);
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "sending SIG%s to monitor over backchannel", signame);
+ break;
+ case CMD_TTYWINCH:
+ sudo_debug_printf(SUDO_DEBUG_INFO, "sending window size change "
+ "to monitor over backchannelL %d x %d",
+ msg->cstat.val & 0xffff, (msg->cstat.val >> 16) & 0xffff);
+ break;
+ default:
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "sending cstat type %d, value %d to monitor over backchannel",
+ msg->cstat.type, msg->cstat.val);
+ break;
+ }
+ TAILQ_REMOVE(&monitor_messages, msg, entries);
+ nsent = send(sock, &msg->cstat, sizeof(msg->cstat), 0);
+ if (nsent != sizeof(msg->cstat)) {
+ if (errno == EPIPE) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR,
+ "broken pipe writing to monitor over backchannel");
+ /* Other end of socket gone, empty out monitor_messages. */
+ free(msg);
+ flush_monitor_messages();
+ /* XXX - need new CMD_ type for monitor errors. */
+ ec->cstat->type = CMD_ERRNO;
+ ec->cstat->val = errno;
+ sudo_ev_loopbreak(ec->evbase);
+ }
+ break;
+ }
+ free(msg);
+ }
+}
+
+/*
+ * Fill in the exec closure and setup initial exec events.
+ * Allocates events for the signal pipe and backchannel.
+ * Forwarded signals on the backchannel are enabled on demand.
+ */
+static void
+fill_exec_closure(struct exec_closure *ec, struct command_status *cstat,
+ struct command_details *details, pid_t sudo_pid, pid_t ppgrp,
+ int backchannel)
+{
+ debug_decl(fill_exec_closure, SUDO_DEBUG_EXEC);
+
+ /* Fill in the non-event part of the closure. */
+ ec->sudo_pid = sudo_pid;
+ ec->ppgrp = ppgrp;
+ ec->cmnd_pid = -1;
+ ec->cstat = cstat;
+ ec->details = details;
+ ec->rows = user_details.ts_rows;
+ ec->cols = user_details.ts_cols;
+
+ /* Reset cstat for running the command. */
+ cstat->type = CMD_INVALID;
+ cstat->val = 0;
+
+ /* Setup event base and events. */
+ ec->evbase = details->evbase;
+ details->evbase = NULL;
+
+ /* Event for command status via backchannel. */
+ ec->backchannel_event = sudo_ev_alloc(backchannel,
+ SUDO_EV_READ|SUDO_EV_PERSIST, backchannel_cb, ec);
+ if (ec->backchannel_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->backchannel_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+ sudo_debug_printf(SUDO_DEBUG_INFO, "backchannel fd %d\n", backchannel);
+
+ /* Events for local signals. */
+ ec->sigint_event = sudo_ev_alloc(SIGINT,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigint_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigint_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigquit_event = sudo_ev_alloc(SIGQUIT,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigquit_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigquit_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigtstp_event = sudo_ev_alloc(SIGTSTP,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigtstp_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigtstp_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigterm_event = sudo_ev_alloc(SIGTERM,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigterm_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigterm_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sighup_event = sudo_ev_alloc(SIGHUP,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sighup_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sighup_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigalrm_event = sudo_ev_alloc(SIGALRM,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigalrm_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigalrm_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigusr1_event = sudo_ev_alloc(SIGUSR1,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigusr1_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigusr1_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigusr2_event = sudo_ev_alloc(SIGUSR2,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigusr2_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigusr2_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigchld_event = sudo_ev_alloc(SIGCHLD,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigchld_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigchld_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ ec->sigwinch_event = sudo_ev_alloc(SIGWINCH,
+ SUDO_EV_SIGINFO, signal_cb_pty, ec);
+ if (ec->sigwinch_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ if (sudo_ev_add(ec->evbase, ec->sigwinch_event, NULL, false) == -1)
+ sudo_fatal("%s", U_("unable to add event to queue"));
+
+ /* The signal forwarding event gets added on demand. */
+ ec->fwdchannel_event = sudo_ev_alloc(backchannel,
+ SUDO_EV_WRITE, fwdchannel_cb, ec);
+ if (ec->fwdchannel_event == NULL)
+ sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+
+ /* Set the default event base. */
+ sudo_ev_base_setdef(ec->evbase);
+
+ debug_return;
+}
+
+/*
+ * Execute a command in a pty, potentially with I/O logging, and
+ * wait for it to finish.
+ * This is a little bit tricky due to how POSIX job control works and
+ * we fact that we have two different controlling terminals to deal with.
+ */
+bool
+exec_pty(struct command_details *details, struct command_status *cstat)
+{
+ int io_pipe[3][2] = { { -1, -1 }, { -1, -1 }, { -1, -1 } };
+ bool interpose[3] = { false, false, false };
+ int sv[2], intercept_sv[2] = { -1, -1 };
+ struct exec_closure ec = { 0 };
+ struct plugin_container *plugin;
+ int evloop_retries = -1;
+ sigset_t set, oset;
+ struct sigaction sa;
+ struct stat sb;
+ pid_t ppgrp, sudo_pid;
+ debug_decl(exec_pty, SUDO_DEBUG_EXEC);
+
+ /*
+ * Allocate a pty if sudo is running in a terminal.
+ */
+ if (!pty_setup(details, user_details.tty))
+ debug_return_bool(false);
+
+ /*
+ * We communicate with the monitor over a bi-directional pair of sockets.
+ * Parent sends signal info to monitor and monitor sends back wait status.
+ */
+ if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1 ||
+ fcntl(sv[0], F_SETFD, FD_CLOEXEC) == -1 ||
+ fcntl(sv[1], F_SETFD, FD_CLOEXEC) == -1)
+ sudo_fatal("%s", U_("unable to create sockets"));
+
+ if (ISSET(details->flags, CD_INTERCEPT|CD_LOG_SUBCMDS)) {
+ if (!ISSET(details->flags, CD_USE_PTRACE)) {
+ /*
+ * Allocate a socketpair for communicating with sudo_intercept.so.
+ * This must be inherited across exec, hence no FD_CLOEXEC.
+ */
+ if (socketpair(PF_UNIX, SOCK_STREAM, 0, intercept_sv) == -1)
+ sudo_fatal("%s", U_("unable to create sockets"));
+ }
+ }
+
+ /*
+ * We don't want to receive SIGTTIN/SIGTTOU.
+ * XXX - this affects tcsetattr() and tcsetpgrp() too.
+ */
+ memset(&sa, 0, sizeof(sa));
+ sigemptyset(&sa.sa_mask);
+ sa.sa_flags = SA_RESTART;
+ sa.sa_handler = SIG_IGN;
+ if (sudo_sigaction(SIGTTIN, &sa, NULL) != 0)
+ sudo_warn(U_("unable to set handler for signal %d"), SIGTTIN);
+ if (sudo_sigaction(SIGTTOU, &sa, NULL) != 0)
+ sudo_warn(U_("unable to set handler for signal %d"), SIGTTOU);
+
+ /*
+ * The policy plugin's session init must be run before we fork
+ * or certain pam modules won't be able to track their state.
+ */
+ if (policy_init_session(details) != true)
+ sudo_fatalx("%s", U_("policy plugin failed session initialization"));
+
+ /*
+ * Child will run the command in the pty, parent will pass data
+ * to and from pty.
+ */
+ init_ttyblock();
+ ppgrp = getpgrp(); /* parent's pgrp, so child can signal us */
+ sudo_pid = getpid();
+
+ /* Determine whether any of std{in,out,err} should be logged. */
+ TAILQ_FOREACH(plugin, &io_plugins, entries) {
+ if (plugin->u.io->log_stdin)
+ interpose[STDIN_FILENO] = true;
+ if (plugin->u.io->log_stdout)
+ interpose[STDOUT_FILENO] = true;
+ if (plugin->u.io->log_stderr)
+ interpose[STDERR_FILENO] = true;
+ }
+
+ /*
+ * Setup stdin/stdout/stderr for command, to be duped after forking.
+ * In background mode there is no stdin.
+ */
+ if (!ISSET(details->flags, CD_BACKGROUND))
+ io_fds[SFD_STDIN] = io_fds[SFD_FOLLOWER];
+ io_fds[SFD_STDOUT] = io_fds[SFD_FOLLOWER];
+ io_fds[SFD_STDERR] = io_fds[SFD_FOLLOWER];
+
+ if (io_fds[SFD_USERTTY] != -1) {
+ /* Read from /dev/tty, write to pty leader */
+ if (!ISSET(details->flags, CD_BACKGROUND)) {
+ io_buf_new(io_fds[SFD_USERTTY], io_fds[SFD_LEADER],
+ log_ttyin, read_callback, write_callback, &ec, &iobufs);
+ }
+
+ /* Read from pty leader, write to /dev/tty */
+ io_buf_new(io_fds[SFD_LEADER], io_fds[SFD_USERTTY],
+ log_ttyout, read_callback, write_callback, &ec, &iobufs);
+
+ /* Are we the foreground process? */
+ foreground = tcgetpgrp(io_fds[SFD_USERTTY]) == ppgrp;
+ sudo_debug_printf(SUDO_DEBUG_INFO, "sudo is running in the %s",
+ foreground ? "foreground" : "background");
+ }
+
+ /*
+ * If stdin, stdout or stderr is not a tty and logging is enabled,
+ * use a pipe to interpose ourselves instead of using the pty fd.
+ */
+ if (io_fds[SFD_STDIN] == -1 || !isatty(STDIN_FILENO)) {
+ if (!interpose[STDIN_FILENO]) {
+ /* Not logging stdin, do not interpose. */
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "stdin not a tty, not logging");
+ if (fstat(STDIN_FILENO, &sb) == 0 && S_ISFIFO(sb.st_mode))
+ pipeline = true;
+ io_fds[SFD_STDIN] = dup(STDIN_FILENO);
+ if (io_fds[SFD_STDIN] == -1)
+ sudo_fatal("dup");
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "stdin not a tty, creating a pipe");
+ pipeline = true;
+ if (pipe2(io_pipe[STDIN_FILENO], O_CLOEXEC) != 0)
+ sudo_fatal("%s", U_("unable to create pipe"));
+ io_buf_new(STDIN_FILENO, io_pipe[STDIN_FILENO][1],
+ log_stdin, read_callback, write_callback, &ec, &iobufs);
+ io_fds[SFD_STDIN] = io_pipe[STDIN_FILENO][0];
+ }
+
+ if (foreground && ppgrp != sudo_pid) {
+ /*
+ * If sudo is not the process group leader and stdin is not
+ * a tty we may be running as a background job via a shell
+ * script. Start the command in the background to avoid
+ * changing the terminal mode from a background process.
+ */
+ SET(details->flags, CD_EXEC_BG);
+ }
+ }
+ if (io_fds[SFD_STDOUT] == -1 || !isatty(STDOUT_FILENO)) {
+ if (!interpose[STDOUT_FILENO]) {
+ /* Not logging stdout, do not interpose. */
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "stdout not a tty, not logging");
+ if (fstat(STDOUT_FILENO, &sb) == 0 && S_ISFIFO(sb.st_mode))
+ pipeline = true;
+ io_fds[SFD_STDOUT] = dup(STDOUT_FILENO);
+ if (io_fds[SFD_STDOUT] == -1)
+ sudo_fatal("dup");
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "stdout not a tty, creating a pipe");
+ pipeline = true;
+ if (pipe2(io_pipe[STDOUT_FILENO], O_CLOEXEC) != 0)
+ sudo_fatal("%s", U_("unable to create pipe"));
+ io_buf_new(io_pipe[STDOUT_FILENO][0], STDOUT_FILENO,
+ log_stdout, read_callback, write_callback, &ec, &iobufs);
+ io_fds[SFD_STDOUT] = io_pipe[STDOUT_FILENO][1];
+ }
+ }
+ if (io_fds[SFD_STDERR] == -1 || !isatty(STDERR_FILENO)) {
+ if (!interpose[STDERR_FILENO]) {
+ /* Not logging stderr, do not interpose. */
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "stderr not a tty, not logging");
+ if (fstat(STDERR_FILENO, &sb) == 0 && S_ISFIFO(sb.st_mode))
+ pipeline = true;
+ io_fds[SFD_STDERR] = dup(STDERR_FILENO);
+ if (io_fds[SFD_STDERR] == -1)
+ sudo_fatal("dup");
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_INFO,
+ "stderr not a tty, creating a pipe");
+ if (pipe2(io_pipe[STDERR_FILENO], O_CLOEXEC) != 0)
+ sudo_fatal("%s", U_("unable to create pipe"));
+ io_buf_new(io_pipe[STDERR_FILENO][0], STDERR_FILENO,
+ log_stderr, read_callback, write_callback, &ec, &iobufs);
+ io_fds[SFD_STDERR] = io_pipe[STDERR_FILENO][1];
+ }
+ }
+
+ if (foreground) {
+ /* Copy terminal attrs from user tty -> pty follower. */
+ if (!sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_FOLLOWER])) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to copy terminal settings to pty", __func__);
+ foreground = false;
+ } else {
+ /* Start in raw mode unless part of a pipeline or backgrounded. */
+ if (!pipeline && !ISSET(details->flags, CD_EXEC_BG)) {
+ if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
+ ttymode = TERM_RAW;
+ }
+ }
+ }
+
+ /*
+ * Block signals until we have our handlers setup in the parent so
+ * we don't miss SIGCHLD if the command exits immediately.
+ */
+ sigfillset(&set);
+ sigprocmask(SIG_BLOCK, &set, &oset);
+
+ /* Check for early termination or suspend signals before we fork. */
+ if (sudo_terminated(cstat)) {
+ sigprocmask(SIG_SETMASK, &oset, NULL);
+ debug_return_bool(true);
+ }
+
+ ec.monitor_pid = sudo_debug_fork();
+ switch (ec.monitor_pid) {
+ case -1:
+ sudo_fatal("%s", U_("unable to fork"));
+ break;
+ case 0:
+ /* child */
+ close(sv[0]);
+ if (intercept_sv[0] != -1)
+ close(intercept_sv[0]);
+ /* Close the other end of the stdin/stdout/stderr pipes and exec. */
+ if (io_pipe[STDIN_FILENO][1] != -1)
+ close(io_pipe[STDIN_FILENO][1]);
+ if (io_pipe[STDOUT_FILENO][0] != -1)
+ close(io_pipe[STDOUT_FILENO][0]);
+ if (io_pipe[STDERR_FILENO][0] != -1)
+ close(io_pipe[STDERR_FILENO][0]);
+ /*
+ * If stdin/stdout is not a tty, start command in the background
+ * since it might be part of a pipeline that reads from /dev/tty.
+ * In this case, we rely on the command receiving SIGTTOU or SIGTTIN
+ * when it needs access to the controlling tty.
+ */
+ exec_monitor(details, &oset, foreground && !pipeline, sv[1],
+ intercept_sv[1]);
+ cstat->type = CMD_ERRNO;
+ cstat->val = errno;
+ if (send(sv[1], cstat, sizeof(*cstat), 0) == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to send status to parent", __func__);
+ }
+ _exit(EXIT_FAILURE);
+ }
+
+ /*
+ * We close the pty follower so only the monitor and command have a
+ * reference to it. This ensures that we can don't block reading
+ * from the leader when the command and monitor have exited.
+ */
+ if (io_fds[SFD_FOLLOWER] != -1) {
+ close(io_fds[SFD_FOLLOWER]);
+ io_fds[SFD_FOLLOWER] = -1;
+ }
+
+ /* Tell the monitor to continue now that the follower is closed. */
+ cstat->type = CMD_SIGNO;
+ cstat->val = 0;
+ while (send(sv[0], cstat, sizeof(*cstat), 0) == -1) {
+ if (errno != EINTR && errno != EAGAIN)
+ sudo_fatal("%s", U_("unable to send message to monitor process"));
+ }
+
+ /* Close the other end of the stdin/stdout/stderr pipes and socketpair. */
+ if (io_pipe[STDIN_FILENO][0] != -1)
+ close(io_pipe[STDIN_FILENO][0]);
+ if (io_pipe[STDOUT_FILENO][1] != -1)
+ close(io_pipe[STDOUT_FILENO][1]);
+ if (io_pipe[STDERR_FILENO][1] != -1)
+ close(io_pipe[STDERR_FILENO][1]);
+ close(sv[1]);
+
+ /* No longer need execfd. */
+ if (details->execfd != -1) {
+ close(details->execfd);
+ details->execfd = -1;
+ }
+
+ /* Set command timeout if specified. */
+ if (ISSET(details->flags, CD_SET_TIMEOUT))
+ alarm(details->timeout);
+
+ /*
+ * Fill in exec closure, allocate event base, signal events and
+ * the backchannel event.
+ */
+ fill_exec_closure(&ec, cstat, details, sudo_pid, ppgrp, sv[0]);
+
+ /* Create event and closure for intercept mode. */
+ if (ISSET(details->flags, CD_INTERCEPT|CD_LOG_SUBCMDS)) {
+ ec.intercept = intercept_setup(intercept_sv[0], ec.evbase, details);
+ if (ec.intercept == NULL)
+ terminate_command(ec.cmnd_pid, true);
+ }
+
+ /* Restore signal mask now that signal handlers are setup. */
+ sigprocmask(SIG_SETMASK, &oset, NULL);
+
+ /*
+ * I/O logging must be in the C locale for floating point numbers
+ * to be logged consistently.
+ */
+ setlocale(LC_ALL, "C");
+
+ /*
+ * In the event loop we pass input from user tty to leader
+ * and pass output from leader to stdout and IO plugin.
+ * Try to recover on ENXIO, it means the tty was revoked.
+ */
+ add_io_events(ec.evbase);
+ do {
+ if (sudo_ev_dispatch(ec.evbase) == -1)
+ sudo_warn("%s", U_("error in event loop"));
+ if (sudo_ev_got_break(ec.evbase)) {
+ /* error from callback or monitor died */
+ sudo_debug_printf(SUDO_DEBUG_ERROR, "event loop exited prematurely");
+ /* XXX: no good way to know if we should terminate the command. */
+ if (cstat->val == CMD_INVALID && ec.cmnd_pid != -1) {
+ /* no status message, kill command */
+ terminate_command(ec.cmnd_pid, true);
+ ec.cmnd_pid = -1;
+ /* TODO: need way to pass an error to the sudo front end */
+ cstat->type = CMD_WSTATUS;
+ cstat->val = W_EXITCODE(1, SIGKILL);
+ }
+ } else if (!sudo_ev_got_exit(ec.evbase)) {
+ switch (errno) {
+ case ENXIO:
+ case EIO:
+ case EBADF:
+ /* /dev/tty was revoked, remove tty events and retry (once) */
+ if (evloop_retries == -1 && io_fds[SFD_USERTTY] != -1) {
+ ev_free_by_fd(ec.evbase, io_fds[SFD_USERTTY]);
+ evloop_retries = 1;
+ }
+ break;
+ }
+ }
+ } while (evloop_retries-- > 0);
+
+ /* Flush any remaining output, free I/O bufs and events, do logout. */
+ pty_finish(&ec, cstat);
+
+ /* Free things up. */
+ free_exec_closure(&ec);
+
+ debug_return_bool(true);
+}
+
+/*
+ * Check for tty size changes.
+ * Passes the new window size to the I/O plugin and to the monitor.
+ */
+static void
+sync_ttysize(struct exec_closure *ec)
+{
+ struct winsize wsize;
+ debug_decl(sync_ttysize, SUDO_DEBUG_EXEC);
+
+ if (ioctl(io_fds[SFD_USERTTY], TIOCGWINSZ, &wsize) == 0) {
+ if (wsize.ws_row != ec->rows || wsize.ws_col != ec->cols) {
+ const unsigned int wsize_packed = (wsize.ws_row & 0xffff) |
+ ((wsize.ws_col & 0xffff) << 16);
+
+ /* Log window change event. */
+ log_winchange(ec, wsize.ws_row, wsize.ws_col);
+
+ /* Send window change event to monitor process. */
+ send_command_status(ec, CMD_TTYWINCH, wsize_packed);
+
+ /* Update rows/cols. */
+ ec->rows = wsize.ws_row;
+ ec->cols = wsize.ws_col;
+ }
+ }
+
+ debug_return;
+}