bsd/kern/tty_tty.c

   1 /*
   2  * Copyright (c) 1997-2006 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*-
  29  * Copyright (c) 1982, 1986, 1991, 1993
  30  *      The Regents of the University of California.  All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  *
  60  *      @(#)tty_tty.c   8.2 (Berkeley) 9/23/93
  61  */
  62
  63 /*
  64  * Indirect driver for controlling tty.
  65  */
  66 #include <sys/param.h>
  67 #include <sys/systm.h>
  68 #include <sys/conf.h>
  69 #include <sys/ioctl.h>
  70 #include <sys/proc_internal.h>
  71 #include <sys/tty.h>
  72 #include <sys/vnode_internal.h>
  73 #include <sys/file_internal.h>
  74 #include <sys/kauth.h>
  75
  76 /* Forward declarations for cdevsw[] entry */
  77 /* XXX we should consider making these static */
  78 int cttyopen(dev_t dev, int flag, int mode, proc_t p);
  79 int cttyread(dev_t dev, struct uio *uio, int flag);
  80 int cttywrite(dev_t dev, struct uio *uio, int flag);
  81 int cttyioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, proc_t p);
  82 int cttyselect(dev_t dev, int flag, void* wql, proc_t p);
  83 static vnode_t cttyvp(proc_t p);
  84
  85 int
  86 cttyopen(dev_t dev, int flag, __unused int mode, proc_t p)
  87 {
  88         vnode_t ttyvp = cttyvp(p);
  89         struct vfs_context context;
  90         int error;
  91
  92         if (ttyvp == NULL)
  93                 return (ENXIO);
  94
  95         context.vc_thread = current_thread();
  96         context.vc_ucred = kauth_cred_proc_ref(p);
  97
  98         /*
  99          * A little hack--this device, used by many processes,
 100          * happens to do an open on another device, which can
 101          * cause unhappiness if the second-level open blocks indefinitely
 102          * (as could be the case if the master side has hung up).  Since
 103          * we know that this driver doesn't care about the serializing
 104          * opens and closes, we can drop the lock.
 105          */
 106         devsw_unlock(dev, S_IFCHR);
 107         error = VNOP_OPEN(ttyvp, flag, &context);
 108         devsw_lock(dev, S_IFCHR);
 109
 110         vnode_put(ttyvp);
 111         kauth_cred_unref(&context.vc_ucred);
 112
 113         return (error);
 114 }
 115
 116 int
 117 cttyread(__unused dev_t dev, struct uio *uio, int flag)
 118 {
 119         vnode_t ttyvp = cttyvp(current_proc());
 120         struct vfs_context context;
 121         int error;
 122
 123         if (ttyvp == NULL)
 124                 return (EIO);
 125
 126         context.vc_thread = current_thread();
 127         context.vc_ucred = NOCRED;
 128
 129         error = VNOP_READ(ttyvp, uio, flag, &context);
 130         vnode_put(ttyvp);
 131
 132         return (error);
 133 }
 134
 135 int
 136 cttywrite(__unused dev_t dev, struct uio *uio, int flag)
 137 {
 138         vnode_t ttyvp = cttyvp(current_proc());
 139         struct vfs_context context;
 140         int error;
 141
 142         if (ttyvp == NULL)
 143                 return (EIO);
 144
 145         context.vc_thread = current_thread();
 146         context.vc_ucred = NOCRED;
 147
 148         error = VNOP_WRITE(ttyvp, uio, flag, &context);
 149         vnode_put(ttyvp);
 150
 151         return (error);
 152 }
 153
 154 int
 155 cttyioctl(__unused dev_t dev, u_long cmd, caddr_t addr, int flag, proc_t p)
 156 {
 157         vnode_t ttyvp = cttyvp(current_proc());
 158         struct vfs_context context;
 159         struct session *sessp;
 160         int error = 0;
 161
 162         if (ttyvp == NULL)
 163                 return (EIO);
 164         if (cmd == TIOCSCTTY)  { /* don't allow controlling tty to be set    */
 165                 error = EINVAL; /* to controlling tty -- infinite recursion */
 166                 goto out;
 167         }
 168         if (cmd == TIOCNOTTY) {
 169                 sessp = proc_session(p);
 170                 if (!SESS_LEADER(p, sessp)) {
 171                         OSBitAndAtomic(~((uint32_t)P_CONTROLT), &p->p_flag);
 172                         if (sessp != SESSION_NULL)
 173                                 session_rele(sessp);
 174                         error = 0;
 175                         goto out;
 176                 } else {
 177                         if (sessp != SESSION_NULL)
 178                                 session_rele(sessp);
 179                         error = EINVAL;
 180                         goto out;
 181                 }
 182         }
 183         context.vc_thread = current_thread();
 184         context.vc_ucred = NOCRED;
 185
 186         error = VNOP_IOCTL(ttyvp, cmd, addr, flag, &context);
 187 out:
 188         vnode_put(ttyvp);
 189         return (error);
 190 }
 191
 192 int
 193 cttyselect(__unused dev_t dev, int flag, void* wql, __unused proc_t p)
 194 {
 195         vnode_t ttyvp = cttyvp(current_proc());
 196         struct vfs_context context;
 197         int error;
 198
 199         context.vc_thread = current_thread();
 200         context.vc_ucred = NOCRED;
 201
 202         if (ttyvp == NULL)
 203                 return (1);     /* try operation to get EOF/failure */
 204         error = VNOP_SELECT(ttyvp, flag, FREAD|FWRITE, wql, &context);
 205         vnode_put(ttyvp);
 206         return (error);
 207 }
 208
 209 /* This returns vnode with ioref */
 210 static vnode_t
 211 cttyvp(proc_t p)
 212 {
 213         vnode_t vp;
 214         int vid;
 215         struct session *sessp;
 216
 217         sessp = proc_session(p);
 218
 219         session_lock(sessp);
 220         vp = (p->p_flag & P_CONTROLT ? sessp->s_ttyvp : NULLVP);
 221         vid = sessp->s_ttyvid;
 222         session_unlock(sessp);
 223
 224         session_rele(sessp);
 225
 226         if (vp != NULLVP) {
 227                 /* cannot get an IO reference, return NULLVP */
 228                 if (vnode_getwithvid(vp, vid) != 0)
 229                         vp = NULLVP;
 230         }
 231         return(vp);
 232 }
 233