xref: /freebsd/sys/kern/tty_tty.c (revision 7f3dea244c40159a41ab22da77a434d7c5b5e85a)
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 1.27 1999/05/31 11:27:41 phk Exp $
35  */
36 
37 /*
38  * Indirect driver for controlling tty.
39  */
40 
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/conf.h>
44 #include <sys/lock.h>
45 #include <sys/proc.h>
46 #include <sys/ttycom.h>
47 #include <sys/vnode.h>
48 #include <sys/kernel.h>
49 
50 static	d_open_t	cttyopen;
51 static	d_read_t	cttyread;
52 static	d_write_t	cttywrite;
53 static	d_ioctl_t	cttyioctl;
54 static	d_poll_t	cttypoll;
55 
56 #define	CDEV_MAJOR	1
57 /* Don't make this static, since fdesc_vnops uses it. */
58 struct cdevsw ctty_cdevsw = {
59 	/* open */	cttyopen,
60 	/* close */	nullclose,
61 	/* read */	cttyread,
62 	/* write */	cttywrite,
63 	/* ioctl */	cttyioctl,
64 	/* stop */	nostop,
65 	/* reset */	noreset,
66 	/* devtotty */	nodevtotty,
67 	/* poll */	cttypoll,
68 	/* mmap */	nommap,
69 	/* strategy */	nostrategy,
70 	/* name */	"ctty",
71 	/* parms */	noparms,
72 	/* maj */	CDEV_MAJOR,
73 	/* dump */	nodump,
74 	/* psize */	nopsize,
75 	/* flags */	D_TTY,
76 	/* maxio */	0,
77 	/* bmaj */	-1
78 };
79 
80 #define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
81 
82 /*ARGSUSED*/
83 static	int
84 cttyopen(dev, flag, mode, p)
85 	dev_t dev;
86 	int flag, mode;
87 	struct proc *p;
88 {
89 	struct vnode *ttyvp = cttyvp(p);
90 	int error;
91 
92 	if (ttyvp == NULL)
93 		return (ENXIO);
94 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
95 #ifdef PARANOID
96 	/*
97 	 * Since group is tty and mode is 620 on most terminal lines
98 	 * and since sessions protect terminals from processes outside
99 	 * your session, this check is probably no longer necessary.
100 	 * Since it inhibits setuid root programs that later switch
101 	 * to another user from accessing /dev/tty, we have decided
102 	 * to delete this test. (mckusick 5/93)
103 	 */
104 	error = VOP_ACCESS(ttyvp,
105 	  (flag&FREAD ? VREAD : 0) | (flag&FWRITE ? VWRITE : 0), p->p_ucred, p);
106 	if (!error)
107 #endif /* PARANOID */
108 		error = VOP_OPEN(ttyvp, flag, NOCRED, p);
109 	VOP_UNLOCK(ttyvp, 0, p);
110 	return (error);
111 }
112 
113 /*ARGSUSED*/
114 static	int
115 cttyread(dev, uio, flag)
116 	dev_t dev;
117 	struct uio *uio;
118 	int flag;
119 {
120 	struct proc *p = uio->uio_procp;
121 	register struct vnode *ttyvp = cttyvp(p);
122 	int error;
123 
124 	if (ttyvp == NULL)
125 		return (EIO);
126 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
127 	error = VOP_READ(ttyvp, uio, flag, NOCRED);
128 	VOP_UNLOCK(ttyvp, 0, p);
129 	return (error);
130 }
131 
132 /*ARGSUSED*/
133 static	int
134 cttywrite(dev, uio, flag)
135 	dev_t dev;
136 	struct uio *uio;
137 	int flag;
138 {
139 	struct proc *p = uio->uio_procp;
140 	struct vnode *ttyvp = cttyvp(uio->uio_procp);
141 	int error;
142 
143 	if (ttyvp == NULL)
144 		return (EIO);
145 	vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY, p);
146 	error = VOP_WRITE(ttyvp, uio, flag, NOCRED);
147 	VOP_UNLOCK(ttyvp, 0, p);
148 	return (error);
149 }
150 
151 /*ARGSUSED*/
152 static	int
153 cttyioctl(dev, cmd, addr, flag, p)
154 	dev_t dev;
155 	u_long cmd;
156 	caddr_t addr;
157 	int flag;
158 	struct proc *p;
159 {
160 	struct vnode *ttyvp = cttyvp(p);
161 
162 	if (ttyvp == NULL)
163 		return (EIO);
164 	if (cmd == TIOCSCTTY)  /* don't allow controlling tty to be set    */
165 		return EINVAL; /* to controlling tty -- infinite recursion */
166 	if (cmd == TIOCNOTTY) {
167 		if (!SESS_LEADER(p)) {
168 			p->p_flag &= ~P_CONTROLT;
169 			return (0);
170 		} else
171 			return (EINVAL);
172 	}
173 	return (VOP_IOCTL(ttyvp, cmd, addr, flag, NOCRED, p));
174 }
175 
176 /*ARGSUSED*/
177 static	int
178 cttypoll(dev, events, p)
179 	dev_t dev;
180 	int events;
181 	struct proc *p;
182 {
183 	struct vnode *ttyvp = cttyvp(p);
184 
185 	if (ttyvp == NULL)
186 		/* try operation to get EOF/failure */
187 		return (seltrue(dev, events, p));
188 	return (VOP_POLL(ttyvp, events, p->p_ucred, p));
189 }
190 
191 static void ctty_drvinit __P((void *unused));
192 static void
193 ctty_drvinit(unused)
194 	void *unused;
195 {
196 
197 	make_dev(&ctty_cdevsw, 0, 0, 0, 0666, "tty");
198 }
199 
200 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL)
201