From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751424AbbARWv6 (ORCPT ); Sun, 18 Jan 2015 17:51:58 -0500 Received: from zill.ext.symas.net ([69.43.206.106]:46868 "EHLO zill.ext.symas.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751098AbbARWv4 (ORCPT ); Sun, 18 Jan 2015 17:51:56 -0500 Message-ID: <54BC2F0A.8040404@symas.com> Date: Sun, 18 Jan 2015 22:09:14 +0000 From: Howard Chu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:37.0) Gecko/20100101 Firefox/37.0 SeaMonkey/2.34a1 MIME-Version: 1.0 To: Peter Hurley , Greg Kroah-Hartman CC: One Thousand Gnomes , Jiri Slaby , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [PATCH] n_tty: Remove LINEMODE support References: <1421616632-4077-1-git-send-email-peter@hurleysoftware.com> In-Reply-To: <1421616632-4077-1-git-send-email-peter@hurleysoftware.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Hurley wrote: > Commit 26df6d13406d1 ("tty: Add EXTPROC support for LINEMODE") added > the undocumented EXTPROC input processing mode, which ignores the ICANON > setting and forces pty slave input to be processed in non-canonical > mode. > > Although intended to provide a transparent mechanism for local line > edit with telnetd (and other remote shell protocols), the transparency > is limited. > > Userspace usage is abandoned; telnetd does not even compile with > LINEMODE support. readline/bash and sshd never supported this. I object to this. Code for all of the above exists and works. I use this code daily. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=585527 http://lists.gnu.org/archive/html/bug-readline/2011-01/msg00004.html https://github.com/hyc/OpenSSH-LINEMODE The lack of LINEMODE support in upstream sshd can only be considered a security hole. http://www.metzdowd.com/pipermail/cryptography/2015-January/024288.html > > Cc: Howard Chu > Signed-off-by: Peter Hurley > --- > drivers/tty/n_tty.c | 22 ++++++---------------- > drivers/tty/pty.c | 24 +----------------------- > 2 files changed, 7 insertions(+), 39 deletions(-) > > diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c > index eb9f114..5120d2b 100644 > --- a/drivers/tty/n_tty.c > +++ b/drivers/tty/n_tty.c > @@ -1562,10 +1562,6 @@ n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp, > c &= 0x7f; > if (I_IUCLC(tty) && L_IEXTEN(tty)) > c = tolower(c); > - if (L_EXTPROC(tty)) { > - put_tty_queue(c, ldata); > - continue; > - } > if (!test_bit(c, ldata->char_map)) > n_tty_receive_char_inline(tty, c); > else if (n_tty_receive_char_special(tty, c) && count) { > @@ -1613,9 +1609,9 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, > > if (ldata->real_raw) > n_tty_receive_buf_real_raw(tty, cp, fp, count); > - else if (ldata->raw || (L_EXTPROC(tty) && !preops)) > + else if (ldata->raw) > n_tty_receive_buf_raw(tty, cp, fp, count); > - else if (tty->closing && !L_EXTPROC(tty)) > + else if (tty->closing) > n_tty_receive_buf_closing(tty, cp, fp, count); > else { > if (ldata->lnext) { > @@ -1637,13 +1633,13 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, > tty->ops->flush_chars(tty); > } > > - if (ldata->icanon && !L_EXTPROC(tty)) > + if (ldata->icanon) > return; > > /* publish read_head to consumer */ > smp_store_release(&ldata->commit_head, ldata->read_head); > > - if ((read_cnt(ldata) >= ldata->minimum_to_wake) || L_EXTPROC(tty)) { > + if (read_cnt(ldata) >= ldata->minimum_to_wake) { > kill_fasync(&tty->fasync, SIGIO, POLL_IN); > if (waitqueue_active(&tty->read_wait)) > wake_up_interruptible_poll(&tty->read_wait, POLLIN); > @@ -1939,7 +1935,7 @@ static inline int input_available_p(struct tty_struct *tty, int poll) > struct n_tty_data *ldata = tty->disc_data; > int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1; > > - if (ldata->icanon && !L_EXTPROC(tty)) > + if (ldata->icanon) > return ldata->canon_head != ldata->read_tail; > else > return ldata->commit_head - ldata->read_tail >= amt; > @@ -1973,7 +1969,6 @@ static int copy_from_read_buf(struct tty_struct *tty, > struct n_tty_data *ldata = tty->disc_data; > int retval; > size_t n; > - bool is_eof; > size_t head = smp_load_acquire(&ldata->commit_head); > size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); > > @@ -1983,14 +1978,9 @@ static int copy_from_read_buf(struct tty_struct *tty, > if (n) { > retval = copy_to_user(*b, read_buf_addr(ldata, tail), n); > n -= retval; > - is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty); > tty_audit_add_data(tty, read_buf_addr(ldata, tail), n, > ldata->icanon); > smp_store_release(&ldata->read_tail, ldata->read_tail + n); > - /* Turn single EOF into zero-length read */ > - if (L_EXTPROC(tty) && ldata->icanon && is_eof && > - (head == ldata->read_tail)) > - n = 0; > *b += n; > *nr -= n; > } > @@ -2257,7 +2247,7 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, > continue; > } > > - if (ldata->icanon && !L_EXTPROC(tty)) { > + if (ldata->icanon) { > retval = canon_copy_from_read_buf(tty, &b, &nr); > if (retval == -EAGAIN) { > retval = 0; > diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c > index ee06b77..01ac182 100644 > --- a/drivers/tty/pty.c > +++ b/drivers/tty/pty.c > @@ -192,20 +192,6 @@ static int pty_get_pktmode(struct tty_struct *tty, int __user *arg) > return put_user(pktmode, arg); > } > > -/* Send a signal to the slave */ > -static int pty_signal(struct tty_struct *tty, int sig) > -{ > - struct pid *pgrp; > - > - if (tty->link) { > - pgrp = tty_get_pgrp(tty->link); > - if (pgrp) > - kill_pgrp(pgrp, sig, 1); > - put_pid(pgrp); > - } > - return 0; > -} > - > static void pty_flush_buffer(struct tty_struct *tty) > { > struct tty_struct *to = tty->link; > @@ -254,15 +240,13 @@ static void pty_set_termios(struct tty_struct *tty, > { > /* See if packet mode change of state. */ > if (tty->link && tty->link->packet) { > - int extproc = (old_termios->c_lflag & EXTPROC) | > - (tty->termios.c_lflag & EXTPROC); > int old_flow = ((old_termios->c_iflag & IXON) && > (old_termios->c_cc[VSTOP] == '\023') && > (old_termios->c_cc[VSTART] == '\021')); > int new_flow = (I_IXON(tty) && > STOP_CHAR(tty) == '\023' && > START_CHAR(tty) == '\021'); > - if ((old_flow != new_flow) || extproc) { > + if (old_flow != new_flow) { > spin_lock_irq(&tty->ctrl_lock); > if (old_flow != new_flow) { > tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); > @@ -271,8 +255,6 @@ static void pty_set_termios(struct tty_struct *tty, > else > tty->ctrl_status |= TIOCPKT_NOSTOP; > } > - if (extproc) > - tty->ctrl_status |= TIOCPKT_IOCTL; > spin_unlock_irq(&tty->ctrl_lock); > wake_up_interruptible(&tty->link->read_wait); > } > @@ -482,8 +464,6 @@ static int pty_bsd_ioctl(struct tty_struct *tty, > return pty_set_pktmode(tty, (int __user *)arg); > case TIOCGPKT: /* Get PT packet mode */ > return pty_get_pktmode(tty, (int __user *)arg); > - case TIOCSIG: /* Send signal to other side of pty */ > - return pty_signal(tty, (int) arg); > case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */ > return -EINVAL; > } > @@ -607,8 +587,6 @@ static int pty_unix98_ioctl(struct tty_struct *tty, > return pty_get_pktmode(tty, (int __user *)arg); > case TIOCGPTN: /* Get PT Number */ > return put_user(tty->index, (unsigned int __user *)arg); > - case TIOCSIG: /* Send signal to other side of pty */ > - return pty_signal(tty, (int) arg); > } > > return -ENOIOCTLCMD; > -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/