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Better handling of multiple sudo processes modifying terminal settings.

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1. Lock the terminal before tcgetattr/tcsetattr
2. Don't restore terminal settings if changed by another process
3. Don't set terminal to raw mode if it is already raw
GitHub issue #312
This commit is contained in:
Todd C. Miller
2023-10-16 19:27:27 -06:00
parent 2f80865e73
commit fabb6264fc
1 changed files with 209 additions and 75 deletions
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276
lib/util/term.c
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@@ -1,7 +1,7 @@
/* /*
* SPDX-License-Identifier: ISC * SPDX-License-Identifier: ISC
* *
* Copyright (c) 2011-2015, 2017-2020 Todd C. Miller <Todd.Miller@sudo.ws> * Copyright (c) 2011-2015, 2017-2023 Todd C. Miller <Todd.Miller@sudo.ws>
* *
* Permission to use, copy, modify, and distribute this software for any * Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above * purpose with or without fee is hereby granted, provided that the above
@@ -82,12 +82,16 @@
#ifndef ECHOKE #ifndef ECHOKE
# define ECHOKE 0 # define ECHOKE 0
#endif #endif
#ifndef PENDIN
# define PENDIN 0
#endif
static struct termios oterm; /* Termios flags to copy between terminals. */
static int changed; #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. */ /* 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_eof;
@@ -129,7 +133,7 @@ tcsetattr_nobg(int fd, int flags, struct termios *tp)
sigaction(SIGTTOU, &sa, &osa); sigaction(SIGTTOU, &sa, &osa);
do { do {
rc = tcsetattr(fd, flags, tp); rc = tcsetattr(fd, flags, tp);
} while (rc != 0 && errno == EINTR && !got_sigttou); } while (rc == -1 && errno == EINTR && !got_sigttou);
sigaction(SIGTTOU, &osa, NULL); sigaction(SIGTTOU, &osa, NULL);
debug_return_int(rc); debug_return_int(rc);
@@ -142,15 +146,75 @@ tcsetattr_nobg(int fd, int flags, struct termios *tp)
bool bool
sudo_term_restore_v1(int fd, bool flush) sudo_term_restore_v1(int fd, bool flush)
{ {
const int flags = flush ? (TCSASOFT|TCSAFLUSH) : (TCSASOFT|TCSADRAIN);
struct termios term = { 0 };
bool ret = false;
debug_decl(sudo_term_restore, SUDO_DEBUG_UTIL); debug_decl(sudo_term_restore, SUDO_DEBUG_UTIL);
if (changed) { if (!changed)
const int flags = flush ? (TCSASOFT|TCSAFLUSH) : (TCSASOFT|TCSADRAIN);
if (tcsetattr_nobg(fd, flags, &oterm) != 0)
debug_return_bool(false);
changed = 0;
}
debug_return_bool(true); 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 ((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;
}
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);
} }
/* /*
@@ -160,22 +224,76 @@ sudo_term_restore_v1(int fd, bool flush)
bool bool
sudo_term_noecho_v1(int fd) sudo_term_noecho_v1(int fd)
{ {
struct termios term; struct termios term = { 0 };
bool ret = false;
debug_decl(sudo_term_noecho, SUDO_DEBUG_UTIL); debug_decl(sudo_term_noecho, SUDO_DEBUG_UTIL);
if (!changed && tcgetattr(fd, &oterm) != 0) sudo_lock_file(fd, SUDO_LOCK);
debug_return_bool(false); if (!changed && tcgetattr(fd, &orig_term) == -1) {
(void) memcpy(&term, &oterm, sizeof(term)); 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); CLR(term.c_lflag, ECHO|ECHONL);
#ifdef VSTATUS #ifdef VSTATUS
term.c_cc[VSTATUS] = _POSIX_VDISABLE; term.c_cc[VSTATUS] = _POSIX_VDISABLE;
#endif #endif
if (tcsetattr_nobg(fd, TCSASOFT|TCSADRAIN, &term) == 0) { if (tcsetattr_nobg(fd, TCSASOFT|TCSADRAIN, &term) == -1) {
changed = 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_oflag, ECHO|ECHONL|ICANON))
debug_return_bool(false);
debug_return_bool(true); 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 };
debug_decl(sudo_term_is_raw, SUDO_DEBUG_UTIL);
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); 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. * Set terminal to raw mode as modified by flags.
@@ -184,28 +302,48 @@ sudo_term_noecho_v1(int fd)
bool bool
sudo_term_raw_v1(int fd, unsigned int flags) sudo_term_raw_v1(int fd, unsigned int flags)
{ {
struct termios term; struct termios term = { 0 };
bool ret = false;
tcflag_t oflag; tcflag_t oflag;
debug_decl(sudo_term_raw, SUDO_DEBUG_UTIL); debug_decl(sudo_term_raw, SUDO_DEBUG_UTIL);
if (!changed && tcgetattr(fd, &oterm) != 0) sudo_lock_file(fd, SUDO_LOCK);
debug_return_bool(false); if (!changed && tcgetattr(fd, &orig_term) == -1) {
(void) memcpy(&term, &oterm, sizeof(term)); 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 * Set terminal to raw mode but optionally enable terminal signals
* and/or preserve output flags. * and/or preserve output flags.
*/ */
term = orig_term;
oflag = term.c_oflag; oflag = term.c_oflag;
cfmakeraw(&term); cfmakeraw(&term);
if (ISSET(flags, SUDO_TERM_ISIG)) if (ISSET(flags, SUDO_TERM_ISIG))
SET(term.c_lflag, ISIG); SET(term.c_lflag, ISIG);
if (ISSET(flags, SUDO_TERM_OFLAG)) if (ISSET(flags, SUDO_TERM_OFLAG))
term.c_oflag = oflag; term.c_oflag = oflag;
if (tcsetattr_nobg(fd, TCSASOFT|TCSADRAIN, &term) == 0) { if (tcsetattr_nobg(fd, TCSASOFT|TCSADRAIN, &term) == -1) {
changed = 1; sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
debug_return_bool(true); "%s: tcsetattr(%d)", __func__, fd);
goto unlock;
} }
debug_return_bool(false); cur_term = term;
changed = true;
ret = true;
unlock:
sudo_lock_file(fd, SUDO_UNLOCK);
debug_return_bool(ret);
} }
/* /*
@@ -215,13 +353,19 @@ sudo_term_raw_v1(int fd, unsigned int flags)
bool bool
sudo_term_cbreak_v1(int fd) sudo_term_cbreak_v1(int fd)
{ {
struct termios term; struct termios term = { 0 };
bool ret = false;
debug_decl(sudo_term_cbreak, SUDO_DEBUG_UTIL); debug_decl(sudo_term_cbreak, SUDO_DEBUG_UTIL);
if (!changed && tcgetattr(fd, &oterm) != 0) sudo_lock_file(fd, SUDO_LOCK);
debug_return_bool(false); if (!changed && tcgetattr(fd, &orig_term) == -1) {
(void) memcpy(&term, &oterm, sizeof(term)); sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: tcgetattr(%d)", __func__, fd);
goto unlock;
}
/* Set terminal to half-cooked mode */ /* Set terminal to half-cooked mode */
term = orig_term;
term.c_cc[VMIN] = 1; term.c_cc[VMIN] = 1;
term.c_cc[VTIME] = 0; term.c_cc[VTIME] = 0;
/* cppcheck-suppress redundantAssignment */ /* cppcheck-suppress redundantAssignment */
@@ -231,21 +375,22 @@ sudo_term_cbreak_v1(int fd)
#ifdef VSTATUS #ifdef VSTATUS
term.c_cc[VSTATUS] = _POSIX_VDISABLE; term.c_cc[VSTATUS] = _POSIX_VDISABLE;
#endif #endif
if (tcsetattr_nobg(fd, TCSASOFT|TCSADRAIN, &term) == 0) { if (tcsetattr_nobg(fd, TCSASOFT|TCSADRAIN, &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_eof = term.c_cc[VEOF];
sudo_term_erase = term.c_cc[VERASE]; sudo_term_erase = term.c_cc[VERASE];
sudo_term_kill = term.c_cc[VKILL]; sudo_term_kill = term.c_cc[VKILL];
changed = 1; cur_term = term;
debug_return_bool(true); changed = true;
} ret = true;
debug_return_bool(false);
}
/* Termios flags to copy between terminals. */ unlock:
#define INPUT_FLAGS (IGNPAR|PARMRK|INPCK|ISTRIP|INLCR|IGNCR|ICRNL|IUCLC|IXON|IXANY|IXOFF|IMAXBEL|IUTF8) sudo_lock_file(fd, SUDO_UNLOCK);
#define OUTPUT_FLAGS (OPOST|OLCUC|ONLCR|OCRNL|ONOCR|ONLRET) debug_return_bool(ret);
#define CONTROL_FLAGS (CS7|CS8|PARENB|PARODD) }
#define LOCAL_FLAGS (ISIG|ICANON|XCASE|ECHO|ECHOE|ECHOK|ECHONL|NOFLSH|TOSTOP|IEXTEN|ECHOCTL|ECHOKE|PENDIN)
/* /*
* Copy terminal settings from one descriptor to another. * Copy terminal settings from one descriptor to another.
@@ -260,10 +405,16 @@ sudo_term_copy_v1(int src, int dst)
struct winsize wsize; struct winsize wsize;
speed_t speed; speed_t speed;
unsigned int i; unsigned int i;
bool ret = false;
debug_decl(sudo_term_copy, SUDO_DEBUG_UTIL); debug_decl(sudo_term_copy, SUDO_DEBUG_UTIL);
if (tcgetattr(src, &tt_src) != 0 || tcgetattr(dst, &tt_dst) != 0) sudo_lock_file(src, SUDO_LOCK);
debug_return_bool(false); 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. */ /* Clear select input, output, control and local flags. */
CLR(tt_dst.c_iflag, INPUT_FLAGS); CLR(tt_dst.c_iflag, INPUT_FLAGS);
@@ -288,35 +439,18 @@ sudo_term_copy_v1(int src, int dst)
speed = cfgetispeed(&tt_src); speed = cfgetispeed(&tt_src);
cfsetispeed(&tt_dst, speed); cfsetispeed(&tt_dst, speed);
if (tcsetattr_nobg(dst, TCSASOFT|TCSAFLUSH, &tt_dst) == -1) if (tcsetattr_nobg(dst, TCSASOFT|TCSAFLUSH, &tt_dst) == -1) {
debug_return_bool(false); sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: tcsetattr(%d)", __func__, dst);
goto unlock;
}
ret = true;
if (ioctl(src, TIOCGWINSZ, &wsize) == 0) if (ioctl(src, TIOCGWINSZ, &wsize) == 0)
(void)ioctl(dst, IOCTL_REQ_CAST TIOCSWINSZ, &wsize); (void)ioctl(dst, IOCTL_REQ_CAST TIOCSWINSZ, &wsize);
debug_return_bool(true); unlock:
} sudo_lock_file(dst, SUDO_UNLOCK);
sudo_lock_file(src, SUDO_UNLOCK);
/* debug_return_bool(ret);
* Returns true if fd refers to a tty in raw mode, else false.
*/
bool
sudo_term_is_raw_v1(int fd)
{
struct termios term;
debug_decl(sudo_term_is_raw, SUDO_DEBUG_UTIL);
if (tcgetattr(fd, &term) != 0)
debug_return_bool(false);
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_oflag, ECHO|ECHONL|ICANON))
debug_return_bool(false);
debug_return_bool(true);
} }