The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_tty.c

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    1 /*      $NetBSD: tty_tty.c,v 1.41 2020/05/23 23:42:43 ad Exp $  */
    2 
    3 /*-
    4  * Copyright (c) 1982, 1986, 1991, 1993, 1995
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of the University nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  *
   31  *      @(#)tty_tty.c   8.2 (Berkeley) 9/23/93
   32  */
   33 
   34 /*
   35  * Indirect driver for controlling tty.
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __KERNEL_RCSID(0, "$NetBSD: tty_tty.c,v 1.41 2020/05/23 23:42:43 ad Exp $");
   40 
   41 #include <sys/param.h>
   42 #include <sys/systm.h>
   43 #include <sys/ioctl.h>
   44 #include <sys/proc.h>
   45 #include <sys/tty.h>
   46 #include <sys/vnode.h>
   47 #include <sys/file.h>
   48 #include <sys/conf.h>
   49 #include <sys/kauth.h>
   50 
   51 /* XXXSMP */
   52 #define cttyvp(p) ((p)->p_lflag & PL_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
   53 
   54 /*ARGSUSED*/
   55 static int
   56 cttyopen(dev_t dev, int flag, int mode, struct lwp *l)
   57 {
   58         struct vnode *ttyvp = cttyvp(l->l_proc);
   59         int error;
   60 
   61         if (ttyvp == NULL)
   62                 return (ENXIO);
   63         vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
   64 #ifdef PARANOID
   65         /*
   66          * Since group is tty and mode is 620 on most terminal lines
   67          * and since sessions protect terminals from processes outside
   68          * your session, this check is probably no longer necessary.
   69          * Since it inhibits setuid root programs that later switch
   70          * to another user from accessing /dev/tty, we have decided
   71          * to delete this test. (mckusick 5/93)
   72          */
   73         error = VOP_ACCESS(ttyvp,
   74           (flag&FREAD ? VREAD : 0) | (flag&FWRITE ? VWRITE : 0), l->l_cred, l);
   75         if (!error)
   76 #endif /* PARANOID */
   77                 error = VOP_OPEN(ttyvp, flag, NOCRED);
   78         VOP_UNLOCK(ttyvp);
   79         return (error);
   80 }
   81 
   82 /*ARGSUSED*/
   83 static int
   84 cttyread(dev_t dev, struct uio *uio, int flag)
   85 {
   86         struct vnode *ttyvp = cttyvp(curproc);
   87         int error;
   88 
   89         if (ttyvp == NULL)
   90                 return (EIO);
   91         vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
   92         error = VOP_READ(ttyvp, uio, flag, NOCRED);
   93         VOP_UNLOCK(ttyvp);
   94         return (error);
   95 }
   96 
   97 /*ARGSUSED*/
   98 static int
   99 cttywrite(dev_t dev, struct uio *uio, int flag)
  100 {
  101         struct vnode *ttyvp = cttyvp(curproc);
  102         int error;
  103 
  104         if (ttyvp == NULL)
  105                 return (EIO);
  106         vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY);
  107         error = VOP_WRITE(ttyvp, uio, flag, NOCRED);
  108         VOP_UNLOCK(ttyvp);
  109         return (error);
  110 }
  111 
  112 /*ARGSUSED*/
  113 static int
  114 cttyioctl(dev_t dev, u_long cmd, void *addr, int flag, struct lwp *l)
  115 {
  116         struct vnode *ttyvp = cttyvp(l->l_proc);
  117         int rv;
  118 
  119         if (ttyvp == NULL)
  120                 return (EIO);
  121         if (cmd == TIOCSCTTY)           /* XXX */
  122                 return (EINVAL);
  123         if (cmd == TIOCNOTTY) {
  124                 mutex_enter(&proc_lock);
  125                 if (!SESS_LEADER(l->l_proc)) {
  126                         l->l_proc->p_lflag &= ~PL_CONTROLT;
  127                         rv = 0;
  128                 } else
  129                         rv = EINVAL;
  130                 mutex_exit(&proc_lock);
  131                 return (rv);
  132         }
  133         return (VOP_IOCTL(ttyvp, cmd, addr, flag, NOCRED));
  134 }
  135 
  136 /*ARGSUSED*/
  137 static int
  138 cttypoll(dev_t dev, int events, struct lwp *l)
  139 {
  140         struct vnode *ttyvp = cttyvp(l->l_proc);
  141 
  142         if (ttyvp == NULL)
  143                 return (seltrue(dev, events, l));
  144         return (VOP_POLL(ttyvp, events));
  145 }
  146 
  147 static int
  148 cttykqfilter(dev_t dev, struct knote *kn)
  149 {
  150         /* This is called from filt_fileattach() by the attaching process. */
  151         struct proc *p = curproc;
  152         struct vnode *ttyvp = cttyvp(p);
  153 
  154         if (ttyvp == NULL)
  155                 return (1);
  156         return (VOP_KQFILTER(ttyvp, kn));
  157 }
  158 
  159 const struct cdevsw ctty_cdevsw = {
  160         .d_open = cttyopen,
  161         .d_close = nullclose,
  162         .d_read = cttyread,
  163         .d_write = cttywrite,
  164         .d_ioctl = cttyioctl,
  165         .d_stop = nullstop,
  166         .d_tty = notty,
  167         .d_poll = cttypoll,
  168         .d_mmap = nommap,
  169         .d_kqfilter = cttykqfilter,
  170         .d_discard = nodiscard,
  171         .d_flag = D_TTY
  172 };

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