/*

 * SPDX-License-Identifier: ISC

 *

 * Copyright (c) 2011-2015, 2017-2023 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.

 */

#include <config.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <errno.h>

#include <signal.h>

#include <termios.h>

#include <unistd.h>

#include <sudo_compat.h>

#include <sudo_debug.h>

#include <sudo_util.h>

/* TCSASOFT is a BSD extension that ignores control flags and speed. */

#ifndef TCSASOFT

# define TCSASOFT 0

#endif

/* Non-standard termios input flags */

#ifndef IUCLC

# define IUCLC    0

#endif

#ifndef IMAXBEL

# define IMAXBEL  0

#endif

#ifndef IUTF8

# define IUTF8  0

#endif

/* Non-standard termios output flags */

#ifndef OLCUC

# define OLCUC  0

#endif

#ifndef ONLCR

# define ONLCR  0

#endif

#ifndef OCRNL

# define OCRNL  0

#endif

#ifndef ONOCR

# define ONOCR  0

#endif

#ifndef ONLRET

# define ONLRET 0

#endif

/* Non-standard termios local flags */

#ifndef XCASE

# define XCASE    0

#endif

#ifndef IEXTEN

# define IEXTEN   0

#endif

#ifndef ECHOCTL

# define ECHOCTL  0

#endif

#ifndef ECHOKE

# define ECHOKE   0

#endif

/* Termios flags to copy between terminals. */

#define INPUT_FLAGS (IGNPAR|PARMRK|INPCK|ISTRIP|INLCR|IGNCR|ICRNL|IUCLC|IXON|IXANY|IXOFF|IMAXBEL|IUTF8)

#define OUTPUT_FLAGS (OPOST|OLCUC|ONLCR|OCRNL|ONOCR|ONLRET)

#define CONTROL_FLAGS (CS7|CS8|PARENB|PARODD)

#define LOCAL_FLAGS (ISIG|ICANON|XCASE|ECHO|ECHOE|ECHOK|ECHONL|NOFLSH|TOSTOP|IEXTEN|ECHOCTL|ECHOKE)

static struct termios orig_term;

static struct termios cur_term;

static bool changed;

/* tgetpass() needs to know the erase and kill chars for cbreak mode. */

sudo_dso_public int sudo_term_eof;

sudo_dso_public int sudo_term_erase;

sudo_dso_public int sudo_term_kill;

static volatile sig_atomic_t got_sigttou;

/*

 * SIGTTOU signal handler for tcsetattr_nobg() that just sets a flag.

 */

static void

sigttou(int signo)

{

    got_sigttou = 1;

}

/*

 * Like tcsetattr() but restarts on EINTR _except_ for SIGTTOU.

 * Returns 0 on success or -1 on failure, setting errno.

 * Sets got_sigttou on failure if interrupted by SIGTTOU.

 */

static int

tcsetattr_nobg(int fd, int flags, struct termios *tp)

{

    struct sigaction sa, osa;

    int rc;

    debug_decl(tcsetattr_nobg, SUDO_DEBUG_UTIL);

    /*

     * If we receive SIGTTOU from tcsetattr() it means we are

     * not in the foreground process group.

     * This should be less racy than using tcgetpgrp().

     */

    memset(&sa, 0, sizeof(sa));

    sigemptyset(&sa.sa_mask);

    sa.sa_handler = sigttou;

    got_sigttou = 0;

    sigaction(SIGTTOU, &sa, &osa);

    do {

  rc = tcsetattr(fd, flags, tp);

    } while (rc == -1 && errno == EINTR && !got_sigttou);

    sigaction(SIGTTOU, &osa, NULL);

    debug_return_int(rc);

}

/*

 * Restore saved terminal settings if we are in the foreground process group.

 * Returns true on success or false on failure.

 */

bool

sudo_term_restore_v2(int fd, int action)

{

    struct termios term = { 0 };

    bool ret = false;

    int flags;

    debug_decl(sudo_term_restore, SUDO_DEBUG_UTIL);

    switch (action) {

    case SUDO_TERM_NOW:

  flags = TCSASOFT|TCSANOW;

  break;

    case SUDO_TERM_DRAIN:

  flags = TCSASOFT|TCSADRAIN;

  break;

    case SUDO_TERM_FLUSH:

  flags = TCSASOFT|TCSAFLUSH;

  break;

    default:

  debug_return_bool(false);

    }

    if (!changed)

  debug_return_bool(true);

    sudo_lock_file(fd, SUDO_LOCK);

    /* Avoid changing term settings if changed out from under us. */

    if (tcgetattr(fd, &term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcgetattr(%d)", __func__, fd);

  goto unlock;

    }

    if ((term.c_iflag & INPUT_FLAGS) != (cur_term.c_iflag & INPUT_FLAGS)) {

  sudo_debug_printf(SUDO_DEBUG_INFO, "%s: not restoring terminal, "

      "c_iflag changed; 0x%x, expected 0x%x", __func__,

      (unsigned int)term.c_iflag, (unsigned int)cur_term.c_iflag);

  /* Not an error. */

  ret = true;

  goto unlock;

    }

    if ((term.c_oflag & OUTPUT_FLAGS) != (cur_term.c_oflag & OUTPUT_FLAGS)) {

  sudo_debug_printf(SUDO_DEBUG_INFO, "%s: not restoring terminal, "

      "c_oflag changed; 0x%x, expected 0x%x", __func__,

      (unsigned int)term.c_oflag, (unsigned int)cur_term.c_oflag);

  /* Not an error. */

  ret = true;

  goto unlock;

    }

#if !TCSASOFT

    /* Only systems without TCSASOFT make changes to c_cflag. */

    if ((term.c_cflag & CONTROL_FLAGS) != (cur_term.c_cflag & CONTROL_FLAGS)) {

  sudo_debug_printf(SUDO_DEBUG_INFO, "%s: not restoring terminal, "

      "c_cflag changed; 0x%x, expected 0x%x", __func__,

      (unsigned int)term.c_cflag, (unsigned int)cur_term.c_cflag);

  /* Not an error. */

  ret = true;

  goto unlock;

    }

#endif

    if ((term.c_lflag & LOCAL_FLAGS) != (cur_term.c_lflag & LOCAL_FLAGS)) {

  sudo_debug_printf(SUDO_DEBUG_INFO, "%s: not restoring terminal, "

      "c_lflag changed; 0x%x, expected 0x%x", __func__,

      (unsigned int)term.c_lflag, (unsigned int)cur_term.c_lflag);

  /* Not an error. */

  ret = true;

  goto unlock;

    }

    if (memcmp(term.c_cc, cur_term.c_cc, sizeof(term.c_cc)) != 0) {

  sudo_debug_printf(SUDO_DEBUG_INFO,

      "%s: not restoring terminal, c_cc[] changed", __func__);

  /* Not an error. */

  ret = true;

  goto unlock;

    }

    if (tcsetattr_nobg(fd, flags, &orig_term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcsetattr(%d)", __func__, fd);

  goto unlock;

    }

    cur_term = orig_term;

    changed = false;

    ret = true;

unlock:

    sudo_lock_file(fd, SUDO_UNLOCK);

    debug_return_bool(ret);

}

bool

sudo_term_restore_v1(int fd, bool flush)

{

    return sudo_term_restore_v2(fd, flush ? SUDO_TERM_FLUSH : SUDO_TERM_DRAIN);

}

/*

 * Disable terminal echo.

 * Returns true on success or false on failure.

 */

bool

sudo_term_noecho_v1(int fd)

{

    struct termios term = { 0 };

    bool ret = false;

    struct stat sb;

    debug_decl(sudo_term_noecho, SUDO_DEBUG_UTIL);

    /* Avoid calling ioctl on non-device to prevent CVE-2023-2002. */

    if (fstat(fd, &sb) != 0 || !S_ISCHR(sb.st_mode))

  debug_return_bool(false);

    sudo_lock_file(fd, SUDO_LOCK);

    if (!changed && tcgetattr(fd, &orig_term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcgetattr(%d)", __func__, fd);

  goto unlock;

    }

    term = orig_term;

    CLR(term.c_lflag, ECHO|ECHONL);

#ifdef VSTATUS

    term.c_cc[VSTATUS] = _POSIX_VDISABLE;

#endif

    if (tcsetattr_nobg(fd, TCSASOFT|TCSAFLUSH, &term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcsetattr(%d)", __func__, fd);

  goto unlock;

    }

    cur_term = term;

    changed = true;

    ret = true;

unlock:

    sudo_lock_file(fd, SUDO_UNLOCK);

    debug_return_bool(ret);

}

/*

 * Returns true if term is in raw mode, else false.

 */

static bool

sudo_term_is_raw_int(struct termios *term)

{

    debug_decl(sudo_term_is_raw_int, SUDO_DEBUG_UTIL);

    if (term->c_cc[VMIN] != 1 || term->c_cc[VTIME] != 0)

  debug_return_bool(false);

    if (ISSET(term->c_oflag, OPOST))

  debug_return_bool(false);

    if (ISSET(term->c_lflag, ECHO|ECHONL|ICANON))

  debug_return_bool(false);

    debug_return_bool(true);

}

/*

 * Returns true if fd refers to a tty in raw mode, else false.

 */

bool

sudo_term_is_raw_v1(int fd)

{

    struct termios term = { 0 };

    struct stat sb;

    debug_decl(sudo_term_is_raw, SUDO_DEBUG_UTIL);

    /* Avoid calling ioctl on non-device to prevent CVE-2023-2002. */

    if (fstat(fd, &sb) != 0 || !S_ISCHR(sb.st_mode))

  debug_return_bool(false);

    sudo_lock_file(fd, SUDO_LOCK);

    if (tcgetattr(fd, &term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcgetattr(%d)", __func__, fd);

  sudo_lock_file(fd, SUDO_UNLOCK);

  debug_return_bool(false);

    }

    sudo_lock_file(fd, SUDO_UNLOCK);

    debug_return_bool(sudo_term_is_raw_int(&term));

}

/*

 * Set terminal to raw mode as modified by flags.

 * Returns true on success or false on failure.

 */

bool

sudo_term_raw_v1(int fd, unsigned int flags)

{

    struct termios term = { 0 };

    bool ret = false;

    struct stat sb;

    tcflag_t oflag;

    debug_decl(sudo_term_raw, SUDO_DEBUG_UTIL);

    /* Avoid calling ioctl on non-device to prevent CVE-2023-2002. */

    if (fstat(fd, &sb) != 0 || !S_ISCHR(sb.st_mode))

  debug_return_bool(false);

    sudo_lock_file(fd, SUDO_LOCK);

    if (!changed && tcgetattr(fd, &orig_term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcgetattr(%d)", __func__, fd);

  goto unlock;

    }

    if (sudo_term_is_raw_int(&term)) {

  sudo_debug_printf(SUDO_DEBUG_INFO, "%s: fd %d already in raw mode",

      __func__, fd);

  ret = true;

  goto unlock;

    }

    /*

     * Set terminal to raw mode but optionally enable terminal signals

     * and/or preserve output flags.

     */

    term = orig_term;

    oflag = term.c_oflag;

    cfmakeraw(&term);

    if (ISSET(flags, SUDO_TERM_ISIG))

  SET(term.c_lflag, ISIG);

    if (ISSET(flags, SUDO_TERM_OFLAG))

  term.c_oflag = oflag;

    if (tcsetattr_nobg(fd, TCSASOFT|TCSADRAIN, &term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcsetattr(%d)", __func__, fd);

  goto unlock;

    }

    cur_term = term;

    changed = true;

    ret = true;

unlock:

    sudo_lock_file(fd, SUDO_UNLOCK);

    debug_return_bool(ret);

}

/*

 * Set terminal to cbreak mode.

 * Returns true on success or false on failure.

 */

bool

sudo_term_cbreak_v3(int fd, int action)

{

    struct termios term = { 0 };

    bool ret = false;

    struct stat sb;

    int flags;

    debug_decl(sudo_term_cbreak, SUDO_DEBUG_UTIL);

    switch (action) {

    case SUDO_TERM_NOW:

  flags = TCSASOFT|TCSANOW;

  break;

    case SUDO_TERM_DRAIN:

  flags = TCSASOFT|TCSADRAIN;

  break;

    case SUDO_TERM_FLUSH:

  flags = TCSASOFT|TCSAFLUSH;

  break;

    default:

  debug_return_bool(false);

    }

    /* Avoid calling ioctl on non-device to prevent CVE-2023-2002. */

    if (fstat(fd, &sb) != 0 || !S_ISCHR(sb.st_mode))

  debug_return_bool(false);

    sudo_lock_file(fd, SUDO_LOCK);

    if (!changed && tcgetattr(fd, &orig_term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcgetattr(%d)", __func__, fd);

  goto unlock;

    }

    /* Set terminal to half-cooked mode */

    term = orig_term;

    term.c_cc[VMIN] = 1;

    term.c_cc[VTIME] = 0;

    /* cppcheck-suppress redundantAssignment */

    CLR(term.c_lflag, ECHO | ECHONL | ICANON | IEXTEN);

    /* cppcheck-suppress redundantAssignment */

    SET(term.c_lflag, ISIG);

#ifdef VSTATUS

    term.c_cc[VSTATUS] = _POSIX_VDISABLE;

#endif

    if (tcsetattr_nobg(fd, flags, &term) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcsetattr(%d)", __func__, fd);

  goto unlock;

    }

    sudo_term_eof = term.c_cc[VEOF];

    sudo_term_erase = term.c_cc[VERASE];

    sudo_term_kill = term.c_cc[VKILL];

    cur_term = term;

    changed = true;

    ret = true;

unlock:

    sudo_lock_file(fd, SUDO_UNLOCK);

    debug_return_bool(ret);

}

bool

sudo_term_cbreak_v2(int fd, bool flush)

{

    return sudo_term_cbreak_v3(fd, flush ? SUDO_TERM_FLUSH : SUDO_TERM_DRAIN);

}

bool

sudo_term_cbreak_v1(int fd)

{

    return sudo_term_cbreak_v2(fd, false);

}

/*

 * Copy terminal settings from one descriptor to another.

 * We cannot simply copy the struct termios as src and dst may be

 * different terminal types (pseudo-tty vs. console or glass tty).

 * Returns true on success or false on failure.

 */

bool

sudo_term_copy_v1(int src, int dst)

{

    struct termios tt_src, tt_dst;

    struct winsize wsize;

    speed_t speed;

    unsigned int i;

    bool ret = false;

    debug_decl(sudo_term_copy, SUDO_DEBUG_UTIL);

    sudo_lock_file(src, SUDO_LOCK);

    sudo_lock_file(dst, SUDO_LOCK);

    if (tcgetattr(src, &tt_src) == -1 || tcgetattr(dst, &tt_dst) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcgetattr", __func__);

  goto unlock;

    }

    /* Clear select input, output, control and local flags. */

    CLR(tt_dst.c_iflag, INPUT_FLAGS);

    CLR(tt_dst.c_oflag, OUTPUT_FLAGS);

    CLR(tt_dst.c_cflag, CONTROL_FLAGS);

    CLR(tt_dst.c_lflag, LOCAL_FLAGS);

    /* Copy select input, output, control and local flags. */

    SET(tt_dst.c_iflag, (tt_src.c_iflag & INPUT_FLAGS));

    SET(tt_dst.c_oflag, (tt_src.c_oflag & OUTPUT_FLAGS));

    SET(tt_dst.c_cflag, (tt_src.c_cflag & CONTROL_FLAGS));

    SET(tt_dst.c_lflag, (tt_src.c_lflag & LOCAL_FLAGS));

    /* Copy special chars from src verbatim. */

    for (i = 0; i < NCCS; i++)

  tt_dst.c_cc[i] = tt_src.c_cc[i];

    /* Copy speed from src (zero output speed closes the connection). */

    if ((speed = cfgetospeed(&tt_src)) == B0)

  speed = B38400;

    cfsetospeed(&tt_dst, speed);

    speed = cfgetispeed(&tt_src);

    cfsetispeed(&tt_dst, speed);

    if (tcsetattr_nobg(dst, TCSASOFT|TCSAFLUSH, &tt_dst) == -1) {

  sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

      "%s: tcsetattr(%d)", __func__, dst);

  goto unlock;

    }

    ret = true;

    if (ioctl(src, TIOCGWINSZ, &wsize) == 0)

  (void)ioctl(dst, IOCTL_REQ_CAST TIOCSWINSZ, &wsize);

unlock:

    sudo_lock_file(dst, SUDO_UNLOCK);

    sudo_lock_file(src, SUDO_UNLOCK);

    debug_return_bool(ret);

}

/*

 * Like isatty(3) but stats the fd and stores the result in sb.

 * Only calls isatty(3) if fd is a character special device.

 * Returns true if a tty, else returns false and sets errno.

 * This is mitigation for CVE-2023-2002.

 */

bool

sudo_isatty_v1(int fd, struct stat *sbp)

{

    bool ret = false;

    struct stat sb;

    debug_decl(sudo_isatty, SUDO_DEBUG_EXEC);

    if (sbp == NULL)

  sbp = &sb;

    if (fstat(fd, sbp) == 0) {

        if (!S_ISCHR(sbp->st_mode)) {

            errno = ENOTTY;

        } else {

            ret = isatty(fd) == 1;

        }

    } else if (sbp != &sb) {

        /* Always initialize sbp. */

        memset(sbp, 0, sizeof(*sbp));

    }

    debug_return_bool(ret);

}