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Diffstat (limited to '')
| -rw-r--r-- | src/exec_pty.c | 1452 |
1 files changed, 1452 insertions, 0 deletions
diff --git a/src/exec_pty.c b/src/exec_pty.c new file mode 100644 index 0000000..1b4bc0e --- /dev/null +++ b/src/exec_pty.c @@ -0,0 +1,1452 @@ +/* + * 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 unsigned int term_raw_flags; +static struct exec_closure pty_ec; + +static void sync_ttysize(struct exec_closure *ec); +static void schedule_signal(struct exec_closure *ec, int signo); + +/* + * Allocate a pty if /dev/tty is a tty. + * Fills in io_fds[SFD_USERTTY], io_fds[SFD_LEADER] and io_fds[SFD_FOLLOWER]. + * Returns the dyamically allocated pty name on success, NULL on failure. + */ +static char * +pty_setup(struct command_details *details) +{ + char *ptyname = NULL; + 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_ptr(NULL); + } + + ptyname = get_pty(&io_fds[SFD_LEADER], &io_fds[SFD_FOLLOWER], + details->cred.euid); + if (ptyname == NULL) + sudo_fatal("%s", U_("unable to allocate pty")); + + /* Add entry to utmp/utmpx? */ + if (ISSET(details->flags, CD_SET_UTMP)) + utmp_login(details->tty, ptyname, io_fds[SFD_FOLLOWER], details->utmp_user); + + /* Update tty name in command details (used by monitor, SELinux, AIX). */ + details->tty = ptyname; + + 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_str(ptyname); +} + +/* + * Restore user's terminal settings and update utmp, as needed. + */ +static void +pty_cleanup(struct exec_closure *ec, int wstatus) +{ + debug_decl(pty_cleanup, SUDO_DEBUG_EXEC); + + /* Restore terminal settings. */ + if (ec->term_raw) { + /* 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")); + ec->term_raw = false; + } + } + + /* Update utmp */ + if (ISSET(ec->details->flags, CD_SET_UTMP) && ec->ptyname != NULL) + utmp_logout(ec->ptyname, wstatus); + + debug_return; +} + +/* + * Cleanup hook for sudo_fatal()/sudo_fatalx() + */ +static void +pty_cleanup_hook(void) +{ + pty_cleanup(&pty_ec, 0); +} + +/* + * Check whether sudo is running in the foreground. + * Updates the foreground flag in the closure. + * 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) { + ec->foreground = ret == ec->ppgrp; + } + } + debug_return_int(ret); +} + +/* + * Restore the terminal when sudo is resumed in response to SIGCONT. + */ +static bool +resume_terminal(struct exec_closure *ec) +{ + debug_decl(resume_terminal, SUDO_DEBUG_EXEC); + + if (check_foreground(ec) == -1) { + /* User's tty was revoked. */ + debug_return_bool(false); + } + + /* Update the pty settings based on the user's terminal. */ + if (!sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_LEADER])) { + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO, + "%s: unable to copy terminal settings to pty", __func__); + debug_return_bool(false); + } + sync_ttysize(ec); + + sudo_debug_printf(SUDO_DEBUG_INFO, "parent is in %s (%s -> %s)", + ec->foreground ? "foreground" : "background", + ec->term_raw ? "raw" : "cooked", + ec->foreground ? "raw" : "cooked"); + + if (ec->foreground) { + /* Foreground process, set tty to raw mode. */ + ec->term_raw = sudo_term_raw(io_fds[SFD_USERTTY], term_raw_flags); + } else { + /* Background process, no access to tty. */ + ec->term_raw = false; + } + + debug_return_bool(true); +} + +/* + * 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, saved_sigcont; + int ret = 0; + debug_decl(suspend_sudo_pty, SUDO_DEBUG_EXEC); + + /* + * Ignore SIGCONT when we suspend to avoid calling resume_terminal() + * multiple times. + */ + memset(&sa, 0, sizeof(sa)); + sigemptyset(&sa.sa_mask); + sa.sa_flags = SA_RESTART; + sa.sa_handler = SIG_DFL; + if (sudo_sigaction(SIGCONT, &sa, &saved_sigcont) != 0) + sudo_warn("%s", U_("unable to set handler for SIGCONT")); + + if (sig2str(signo, signame) == -1) + (void)snprintf(signame, sizeof(signame), "%d", signo); + + 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 (!ec->foreground) { + if (check_foreground(ec) == -1) { + /* User's tty was revoked. */ + break; + } + } + if (ec->foreground) { + sudo_debug_printf(SUDO_DEBUG_INFO, + "%s: command received SIG%s, parent running in the foregound", + __func__, signame); + if (!ec->term_raw) { + if (sudo_term_raw(io_fds[SFD_USERTTY], term_raw_flags)) + ec->term_raw = true; + } + ret = SIGCONT_FG; /* resume command in foreground */ + break; + } + FALLTHROUGH; + case SIGSTOP: + case SIGTSTP: + default: + /* Flush any remaining output and deschedule I/O events. */ + del_io_events(true); + + /* Restore original tty mode before suspending. */ + if (ec->term_raw) { + if (!sudo_term_restore(io_fds[SFD_USERTTY], false)) + sudo_warn("%s", U_("unable to restore terminal settings")); + ec->term_raw = false; + } + + /* Log the suspend event. */ + log_suspend(ec, signo); + + /* Suspend self and continue command when we resume. */ + if (signo != SIGSTOP) { + if (sudo_sigaction(signo, &sa, &osa) != 0) + sudo_warn(U_("unable to set handler for SIG%s"), signame); + } + + /* + * 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, "%s: killpg(%d, SIG%s) [parent]", + __func__, (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, + "%s: no parent to suspend, terminating command.", __func__); + terminate_command(ec->cmnd_pid, true); + ec->cmnd_pid = -1; + } + + if (signo != SIGSTOP) { + if (sudo_sigaction(signo, &osa, NULL) != 0) + sudo_warn(U_("unable to restore handler for SIG%s"), signame); + } + + /* If we failed to suspend, the command is no longer running. */ + if (ec->cmnd_pid == -1) + break; + + /* Log the resume event. */ + log_suspend(ec, SIGCONT); + + /* Update the pty's terminal settings and restore /dev/tty settings. */ + if (!resume_terminal(ec)) + break; + + /* + * We always resume the command in the foreground if sudo itself + * is the foreground process (and we were able to set /dev/tty to + * raw mode). 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. + */ + ret = ec->term_raw ? SIGCONT_FG : SIGCONT_BG; + break; + } + + if (sudo_sigaction(SIGCONT, &saved_sigcont, NULL) != 0) + sudo_warn("%s", U_("unable to restore handler for SIGCONT")); + + 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, (unsigned int)n, iob)) { + terminate_command(iob->ec->cmnd_pid, true); + iob->ec->cmnd_pid = -1; + } + iob->len += (unsigned int)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 %u 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 of %u bytes to fd %d", n, iob->len - iob->off, fd); + iob->off += (unsigned int)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) || + (iob->ec->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 and update utmp. */ + pty_cleanup(ec, cstat->type == CMD_WSTATUS ? cstat->val : 0); + + debug_return; +} + +/* + * Send command status to the monitor (currently just signal forwarding). + */ +static void +send_command_status(struct exec_closure *ec, int type, int val) +{ + struct monitor_message *msg; + debug_decl(send_command_status, 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) +{ + debug_decl(schedule_signal, SUDO_DEBUG_EXEC); + + if (signo == 0) + debug_return; + + if (sudo_debug_needed(SUDO_DEBUG_DIAG)) { + char signame[SIG2STR_MAX]; + 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); + } 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)) { + if (sudo_debug_needed(SUDO_DEBUG_INFO)) { + 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); + } 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; + debug_decl(signal_cb_pty, SUDO_DEBUG_EXEC); + + if (ec->monitor_pid == -1) + debug_return; + + if (sudo_debug_needed(SUDO_DEBUG_DIAG)) { + char signame[SIG2STR_MAX]; + 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 SIGCONT: + resume_terminal(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; + 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 (sudo_debug_needed(SUDO_DEBUG_INFO)) { + char signame[SIG2STR_MAX]; + 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; + 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, const struct user_details *user_details, + struct sudo_event_base *evbase, 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 = evbase; + + /* 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->sigcont_event = sudo_ev_alloc(SIGCONT, + SUDO_EV_SIGINFO, signal_cb_pty, ec); + if (ec->sigcont_event == NULL) + sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory")); + if (sudo_ev_add(ec->evbase, ec->sigcont_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, + const struct user_details *user_details, struct sudo_event_base *evbase, + struct command_status *cstat) +{ + int io_pipe[3][2] = { { -1, -1 }, { -1, -1 }, { -1, -1 } }; + bool interpose[3] = { false, false, false }; + struct stat sb, tty_sbuf, *tty_sb = NULL; + int sv[2], intercept_sv[2] = { -1, -1 }; + struct exec_closure *ec = &pty_ec; + struct plugin_container *plugin; + int evloop_retries = -1; + bool cmnd_foreground; + sigset_t set, oset; + struct sigaction sa; + pid_t ppgrp, sudo_pid; + debug_decl(exec_pty, SUDO_DEBUG_EXEC); + + /* + * Allocate a pty if sudo is running in a terminal. + */ + ec->ptyname = pty_setup(details); + if (ec->ptyname == NULL) + debug_return_bool(false); + + /* Register cleanup function */ + sudo_fatal_callback_register(pty_cleanup_hook); + + /* + * 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. + */ + 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); + } + + /* 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); + + /* Are we the foreground process? */ + ec->foreground = tcgetpgrp(io_fds[SFD_USERTTY]) == ppgrp; + sudo_debug_printf(SUDO_DEBUG_INFO, "sudo is running in the %s", + ec->foreground ? "foreground" : "background"); + } + + /* + * If stdin, stdout or stderr is not the user's tty and logging is + * enabled, use a pipe to interpose ourselves instead of using the + * pty fd. We always use a pipe for stdin when in background mode. + */ + if (user_details->tty != NULL && stat(user_details->tty, &tty_sbuf) != -1) + tty_sb = &tty_sbuf; + + if (!fd_matches_tty(STDIN_FILENO, tty_sb, &sb)) { + if (!interpose[STDIN_FILENO]) { + /* Not logging stdin, do not interpose. */ + sudo_debug_printf(SUDO_DEBUG_INFO, + "stdin not user's tty, not logging"); + if (S_ISFIFO(sb.st_mode)) + SET(details->flags, CD_EXEC_BG); + 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 user's tty, creating a pipe"); + SET(details->flags, CD_EXEC_BG); + 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); + io_fds[SFD_STDIN] = io_pipe[STDIN_FILENO][0]; + } + + if (ec->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); + } + } else if (ISSET(details->flags, CD_BACKGROUND)) { + /* + * Running in background (sudo -b), no access to terminal input. + * In non-pty mode, the command runs in an orphaned process + * group and reads from the controlling terminal fail with EIO. + * We cannot do the same while running in a pty but if we set + * stdin to a half-closed pipe, reads from it will get EOF. + */ + sudo_debug_printf(SUDO_DEBUG_INFO, + "terminal input not available, creating empty pipe"); + SET(details->flags, CD_EXEC_BG); + if (pipe2(io_pipe[STDIN_FILENO], O_CLOEXEC) != 0) + sudo_fatal("%s", U_("unable to create pipe")); + io_fds[SFD_STDIN] = io_pipe[STDIN_FILENO][0]; + close(io_pipe[STDIN_FILENO][1]); + io_pipe[STDIN_FILENO][1] = -1; + } + if (!fd_matches_tty(STDOUT_FILENO, tty_sb, &sb)) { + if (!interpose[STDOUT_FILENO]) { + /* Not logging stdout, do not interpose. */ + sudo_debug_printf(SUDO_DEBUG_INFO, + "stdout not user's tty, not logging"); + if (S_ISFIFO(sb.st_mode)) { + SET(details->flags, CD_EXEC_BG); + term_raw_flags = SUDO_TERM_OFLAG; + } + 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 user's tty, creating a pipe"); + SET(details->flags, CD_EXEC_BG); + term_raw_flags = SUDO_TERM_OFLAG; + 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); + io_fds[SFD_STDOUT] = io_pipe[STDOUT_FILENO][1]; + } + } + if (!fd_matches_tty(STDERR_FILENO, tty_sb, &sb)) { + if (!interpose[STDERR_FILENO]) { + /* Not logging stderr, do not interpose. */ + sudo_debug_printf(SUDO_DEBUG_INFO, + "stderr not user's tty, not logging"); + io_fds[SFD_STDERR] = dup(STDERR_FILENO); + if (io_fds[SFD_STDERR] == -1) + sudo_fatal("dup"); + } else { + sudo_debug_printf(SUDO_DEBUG_INFO, + "stderr /dev/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); + io_fds[SFD_STDERR] = io_pipe[STDERR_FILENO][1]; + } + } + + /* + * Copy terminal settings from user tty -> pty. If sudo is a + * background process, we'll re-init the pty when foregrounded. + */ + if (!sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_LEADER])) { + sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO, + "%s: unable to copy terminal settings to pty", __func__); + ec->foreground = false; + } + /* Start in raw mode unless the command will run in the background. */ + cmnd_foreground = ec->foreground && !ISSET(details->flags, CD_EXEC_BG); + if (cmnd_foreground) { + if (sudo_term_raw(io_fds[SFD_USERTTY], 0)) + ec->term_raw = true; + } + + sudo_debug_printf(SUDO_DEBUG_INFO, + "%s: follower: %d, stdin: %d, stdout: %d, stderr: %d", __func__, + io_fds[SFD_FOLLOWER], io_fds[SFD_STDIN], io_fds[SFD_STDOUT], + io_fds[SFD_STDERR]); + + /* + * 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]); + + /* Only run the cleanup hook in the parent. */ + sudo_fatal_callback_deregister(pty_cleanup_hook); + + /* + * If stdin/stdout is not the user's tty, start the 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, cmnd_foreground, 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); + /* NOTREACHED */ + } + + /* + * 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; + if (send(sv[0], cstat, sizeof(*cstat), 0) == -1) + 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, user_details, evbase, + 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); + 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); + + /* De-register cleanup hook, the pty is going away. */ + sudo_fatal_callback_deregister(pty_cleanup_hook); + + /* 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); +} + +/* + * Propagate tty size change to pty being used by the command, pass + * new window size to I/O plugins and deliver SIGWINCH to the command. + */ +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) { + sudo_debug_printf(SUDO_DEBUG_INFO, "%s: %d x %d -> %hd x %hd", + __func__, ec->rows, ec->cols, wsize.ws_row, wsize.ws_col); + + /* Log window change event. */ + log_winchange(ec, wsize.ws_row, wsize.ws_col); + + /* Update pty window size and send command SIGWINCH. */ + (void)ioctl(io_fds[SFD_LEADER], IOCTL_REQ_CAST TIOCSWINSZ, &wsize); + killpg(ec->cmnd_pid, SIGWINCH); + + /* Update rows/cols. */ + ec->rows = wsize.ws_row; + ec->cols = wsize.ws_col; + } + } + + debug_return; +} |