1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Portions of this software were developed under sponsorship from Snow
8 * B.V., the Netherlands.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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
32 #include <sys/param.h>
33 #include <sys/conf.h>
34 #include <sys/eventhandler.h>
35 #include <sys/fcntl.h>
36 #include <sys/kernel.h>
37 #include <sys/module.h>
38 #include <sys/proc.h>
39 #include <sys/sysctl.h>
40 #include <sys/syslog.h>
41 #include <sys/systm.h>
42 #include <sys/tty.h>
43
44 /*
45 * This driver implements a BSD-style compatibility naming scheme for
46 * the pts(4) driver. We just call into pts(4) to create the actual PTY.
47 * To make sure we don't use the same PTY multiple times, we abuse
48 * si_drv1 inside the cdev to mark whether the PTY is in use.
49 *
50 * It also implements a /dev/ptmx device node, which is useful for Linux
51 * binary emulation.
52 */
53
54 static unsigned pty_warningcnt = 1;
55 SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW,
56 &pty_warningcnt, 0,
57 "Warnings that will be triggered upon legacy PTY allocation");
58
59 static int
ptydev_fdopen(struct cdev * dev,int fflags,struct thread * td,struct file * fp)60 ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp)
61 {
62 int error;
63 char name[6]; /* "ttyXX" */
64
65 if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1))
66 return (EBUSY);
67
68 /* Generate device name and create PTY. */
69 strlcpy(name, devtoname(dev), sizeof(name));
70 name[0] = 't';
71
72 error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name);
73 if (error != 0) {
74 destroy_dev_sched(dev);
75 return (error);
76 }
77
78 /* Raise a warning when a legacy PTY has been allocated. */
79 counted_warning(&pty_warningcnt, "is using legacy pty devices");
80
81 return (0);
82 }
83
84 static struct cdevsw ptydev_cdevsw = {
85 .d_version = D_VERSION,
86 .d_fdopen = ptydev_fdopen,
87 .d_name = "ptydev",
88 };
89
90 static void
pty_clone(void * arg,struct ucred * cr,char * name,int namelen,struct cdev ** dev)91 pty_clone(void *arg, struct ucred *cr, char *name, int namelen,
92 struct cdev **dev)
93 {
94 struct make_dev_args mda;
95 int error;
96
97 /* Cloning is already satisfied. */
98 if (*dev != NULL)
99 return;
100
101 /* Only catch /dev/ptyXX. */
102 if (namelen != 5 || bcmp(name, "pty", 3) != 0)
103 return;
104
105 /* Only catch /dev/pty[l-sL-S]X. */
106 if (!(name[3] >= 'l' && name[3] <= 's') &&
107 !(name[3] >= 'L' && name[3] <= 'S'))
108 return;
109
110 /* Only catch /dev/pty[l-sL-S][0-9a-v]. */
111 if (!(name[4] >= '0' && name[4] <= '9') &&
112 !(name[4] >= 'a' && name[4] <= 'v'))
113 return;
114
115 /* Create the controller device node. */
116 make_dev_args_init(&mda);
117 mda.mda_flags = MAKEDEV_CHECKNAME | MAKEDEV_REF;
118 mda.mda_devsw = &ptydev_cdevsw;
119 mda.mda_uid = UID_ROOT;
120 mda.mda_gid = GID_WHEEL;
121 mda.mda_mode = 0666;
122 error = make_dev_s(&mda, dev, "%s", name);
123 if (error != 0)
124 *dev = NULL;
125 }
126
127 static int
ptmx_fdopen(struct cdev * dev __unused,int fflags,struct thread * td,struct file * fp)128 ptmx_fdopen(struct cdev *dev __unused, int fflags, struct thread *td,
129 struct file *fp)
130 {
131
132 return (pts_alloc(fflags & (FREAD|FWRITE), td, fp));
133 }
134
135 static struct cdevsw ptmx_cdevsw = {
136 .d_version = D_VERSION,
137 .d_fdopen = ptmx_fdopen,
138 .d_name = "ptmx",
139 };
140
141 static int
pty_modevent(module_t mod,int type,void * data)142 pty_modevent(module_t mod, int type, void *data)
143 {
144
145 switch(type) {
146 case MOD_LOAD:
147 EVENTHANDLER_REGISTER(dev_clone, pty_clone, 0, 1000);
148 make_dev_credf(MAKEDEV_ETERNAL_KLD, &ptmx_cdevsw, 0, NULL,
149 UID_ROOT, GID_WHEEL, 0666, "ptmx");
150 break;
151 case MOD_SHUTDOWN:
152 break;
153 case MOD_UNLOAD:
154 /* XXX: No unloading support yet. */
155 return (EBUSY);
156 default:
157 return (EOPNOTSUPP);
158 }
159
160 return (0);
161 }
162
163 DEV_MODULE(pty, pty_modevent, NULL);
164