xref: /freebsd/sys/kern/tty_tty.c (revision 380a989b3223d455375b4fae70fd0b9bdd43bafb)
1 /*-
2  * Copyright (c) 1982, 1986, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  *	@(#)tty_tty.c	8.2 (Berkeley) 9/23/93
34  * $Id: tty_tty.c,v 1.24 1998/06/07 17:11:44 dfr Exp $
35  */
36 
37 /*
38  * Indirect driver for controlling tty.
39  */
40 
41 #include "opt_devfs.h"
42 
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/conf.h>
46 #include <sys/lock.h>
47 #include <sys/proc.h>
48 #include <sys/ttycom.h>
49 #include <sys/vnode.h>
50 #include <sys/kernel.h>
51 #ifdef DEVFS
52 #include <sys/devfsext.h>
53 #endif /*DEVFS*/
54 
55 static	d_open_t	cttyopen;
56 static	d_read_t	cttyread;
57 static	d_write_t	cttywrite;
58 static	d_ioctl_t	cttyioctl;
59 static	d_poll_t	cttypoll;
60 
61 #define	CDEV_MAJOR	1
62 /* Don't make this static, since fdesc_vnops uses it. */
63 struct cdevsw	ctty_cdevsw = {
64 	cttyopen,	nullclose,	cttyread,	cttywrite,
65 	cttyioctl,	nullstop,	nullreset,	nodevtotty,
66 	cttypoll,	nommap,		NULL,		"ctty",
67 	NULL,		-1,		nodump,		nopsize,
68 	D_TTY,
69 };
70 
71 #define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
72 
73 /*ARGSUSED*/
74 static	int
75 cttyopen(dev, flag, mode, p)
76 	dev_t dev;
77 	int flag, mode;
78 	struct proc *p;
79 {
80 	struct vnode *ttyvp = cttyvp(p);
81 	int error;
82 
83 	if (ttyvp == NULL)
84 		return (ENXIO);
85 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
86 #ifdef PARANOID
87 	/*
88 	 * Since group is tty and mode is 620 on most terminal lines
89 	 * and since sessions protect terminals from processes outside
90 	 * your session, this check is probably no longer necessary.
91 	 * Since it inhibits setuid root programs that later switch
92 	 * to another user from accessing /dev/tty, we have decided
93 	 * to delete this test. (mckusick 5/93)
94 	 */
95 	error = VOP_ACCESS(ttyvp,
96 	  (flag&FREAD ? VREAD : 0) | (flag&FWRITE ? VWRITE : 0), p->p_ucred, p);
97 	if (!error)
98 #endif /* PARANOID */
99 		error = VOP_OPEN(ttyvp, flag, NOCRED, p);
100 	VOP_UNLOCK(ttyvp, 0, p);
101 	return (error);
102 }
103 
104 /*ARGSUSED*/
105 static	int
106 cttyread(dev, uio, flag)
107 	dev_t dev;
108 	struct uio *uio;
109 	int flag;
110 {
111 	struct proc *p = uio->uio_procp;
112 	register struct vnode *ttyvp = cttyvp(p);
113 	int error;
114 
115 	if (ttyvp == NULL)
116 		return (EIO);
117 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
118 	error = VOP_READ(ttyvp, uio, flag, NOCRED);
119 	VOP_UNLOCK(ttyvp, 0, p);
120 	return (error);
121 }
122 
123 /*ARGSUSED*/
124 static	int
125 cttywrite(dev, uio, flag)
126 	dev_t dev;
127 	struct uio *uio;
128 	int flag;
129 {
130 	struct proc *p = uio->uio_procp;
131 	struct vnode *ttyvp = cttyvp(uio->uio_procp);
132 	int error;
133 
134 	if (ttyvp == NULL)
135 		return (EIO);
136 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
137 	error = VOP_WRITE(ttyvp, uio, flag, NOCRED);
138 	VOP_UNLOCK(ttyvp, 0, p);
139 	return (error);
140 }
141 
142 /*ARGSUSED*/
143 static	int
144 cttyioctl(dev, cmd, addr, flag, p)
145 	dev_t dev;
146 	u_long cmd;
147 	caddr_t addr;
148 	int flag;
149 	struct proc *p;
150 {
151 	struct vnode *ttyvp = cttyvp(p);
152 
153 	if (ttyvp == NULL)
154 		return (EIO);
155 	if (cmd == TIOCSCTTY)  /* don't allow controlling tty to be set    */
156 		return EINVAL; /* to controlling tty -- infinite recursion */
157 	if (cmd == TIOCNOTTY) {
158 		if (!SESS_LEADER(p)) {
159 			p->p_flag &= ~P_CONTROLT;
160 			return (0);
161 		} else
162 			return (EINVAL);
163 	}
164 	return (VOP_IOCTL(ttyvp, cmd, addr, flag, NOCRED, p));
165 }
166 
167 /*ARGSUSED*/
168 static	int
169 cttypoll(dev, events, p)
170 	dev_t dev;
171 	int events;
172 	struct proc *p;
173 {
174 	struct vnode *ttyvp = cttyvp(p);
175 
176 	if (ttyvp == NULL)
177 		/* try operation to get EOF/failure */
178 		return (seltrue(dev, events, p));
179 	return (VOP_POLL(ttyvp, events, p->p_ucred, p));
180 }
181 
182 static	int	ctty_devsw_installed;
183 #ifdef DEVFS
184 static 	void	*ctty_devfs_token;
185 #endif
186 
187 static void ctty_drvinit __P((void *unused));
188 static void
189 ctty_drvinit(unused)
190 	void *unused;
191 {
192 	dev_t dev;
193 
194 	if( ! ctty_devsw_installed ) {
195 		dev = makedev(CDEV_MAJOR,0);
196 		cdevsw_add(&dev,&ctty_cdevsw,NULL);
197 		ctty_devsw_installed = 1;
198 #ifdef DEVFS
199 		ctty_devfs_token =
200 			devfs_add_devswf(&ctty_cdevsw, 0, DV_CHR, 0, 0,
201 					0666, "tty");
202 #endif
203     	}
204 }
205 
206 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)
207