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When copying terminal settings from one tty to another only copy a

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subset of the flags.  Sudo now copies the same set of flags that
OpenSSH uses, which should be safe.
This commit is contained in:
Todd C. Miller
2017-06-15 12:59:46 -06:00
parent f5b60ef749
commit c77c5d026a
1 changed files with 73 additions and 8 deletions
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81
lib/util/term.c
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2011-2015 Todd C. Miller <Todd.Miller@courtesan.com>
* Copyright (c) 2011-2015, 2017 Todd C. Miller <Todd.Miller@courtesan.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@@ -34,17 +34,54 @@
#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
#ifndef ECHONL
# define ECHONL 0
/* 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 IUCLC
# define IUCLC 0
#ifndef ECHOCTL
# define ECHOCTL 0
#endif
#ifndef ECHOKE
# define ECHOKE 0
#endif
#ifndef PENDIN
# define PENDIN 0
#endif
#ifndef _POSIX_VDISABLE
@@ -202,19 +239,47 @@ sudo_term_cbreak_v1(int fd)
debug_return_bool(false);
}
/* 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|PENDIN)
/*
* 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;
struct termios tt_src, tt_dst;
speed_t speed;
int i;
debug_decl(sudo_term_copy, SUDO_DEBUG_UTIL)
if (tcgetattr(src, &tt) != 0)
if (tcgetattr(src, &tt_src) != 0 || tcgetattr(dst, &tt_dst) != 0)
debug_return_bool(false);
if (tcsetattr_nobg(dst, TCSASOFT|TCSAFLUSH, &tt) == 0)
/* Copy select input, output, control and local flags. */
tt_dst.c_iflag |= (tt_src.c_iflag & INPUT_FLAGS);
tt_dst.c_oflag |= (tt_src.c_oflag & OUTPUT_FLAGS);
tt_dst.c_cflag |= (tt_src.c_cflag & CONTROL_FLAGS);
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) == 0)
debug_return_bool(true);
debug_return_bool(false);
}