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*/
55static int
56cttyopen(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*/
83static int
84cttyread(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*/
98static int
99cttywrite(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*/
113static int
114cttyioctl(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*/
137static int
138cttypoll(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
147static int
148cttykqfilter(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
159const 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};
173