1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/conf.h> 37 #include <sys/eventhandler.h> 38 #include <sys/fcntl.h> 39 #include <sys/kernel.h> 40 #include <sys/module.h> 41 #include <sys/proc.h> 42 #include <sys/sysctl.h> 43 #include <sys/syslog.h> 44 #include <sys/systm.h> 45 #include <sys/tty.h> 46 47 /* 48 * This driver implements a BSD-style compatibility naming scheme for 49 * the pts(4) driver. We just call into pts(4) to create the actual PTY. 50 * To make sure we don't use the same PTY multiple times, we abuse 51 * si_drv1 inside the cdev to mark whether the PTY is in use. 52 * 53 * It also implements a /dev/ptmx device node, which is useful for Linux 54 * binary emulation. 55 */ 56 57 static unsigned pty_warningcnt = 1; 58 SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW, 59 &pty_warningcnt, 0, 60 "Warnings that will be triggered upon legacy PTY allocation"); 61 62 static int 63 ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp) 64 { 65 int error; 66 char name[6]; /* "ttyXX" */ 67 68 if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1)) 69 return (EBUSY); 70 71 /* Generate device name and create PTY. */ 72 strlcpy(name, devtoname(dev), sizeof(name)); 73 name[0] = 't'; 74 75 error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name); 76 if (error != 0) { 77 destroy_dev_sched(dev); 78 return (error); 79 } 80 81 /* Raise a warning when a legacy PTY has been allocated. */ 82 counted_warning(&pty_warningcnt, "is using legacy pty devices"); 83 84 return (0); 85 } 86 87 static struct cdevsw ptydev_cdevsw = { 88 .d_version = D_VERSION, 89 .d_fdopen = ptydev_fdopen, 90 .d_name = "ptydev", 91 }; 92 93 static void 94 pty_clone(void *arg, struct ucred *cr, char *name, int namelen, 95 struct cdev **dev) 96 { 97 struct make_dev_args mda; 98 int error; 99 100 /* Cloning is already satisfied. */ 101 if (*dev != NULL) 102 return; 103 104 /* Only catch /dev/ptyXX. */ 105 if (namelen != 5 || bcmp(name, "pty", 3) != 0) 106 return; 107 108 /* Only catch /dev/pty[l-sL-S]X. */ 109 if (!(name[3] >= 'l' && name[3] <= 's') && 110 !(name[3] >= 'L' && name[3] <= 'S')) 111 return; 112 113 /* Only catch /dev/pty[l-sL-S][0-9a-v]. */ 114 if (!(name[4] >= '0' && name[4] <= '9') && 115 !(name[4] >= 'a' && name[4] <= 'v')) 116 return; 117 118 /* Create the controller device node. */ 119 make_dev_args_init(&mda); 120 mda.mda_flags = MAKEDEV_CHECKNAME | MAKEDEV_REF; 121 mda.mda_devsw = &ptydev_cdevsw; 122 mda.mda_uid = UID_ROOT; 123 mda.mda_gid = GID_WHEEL; 124 mda.mda_mode = 0666; 125 error = make_dev_s(&mda, dev, "%s", name); 126 if (error != 0) 127 *dev = NULL; 128 } 129 130 static int 131 ptmx_fdopen(struct cdev *dev __unused, int fflags, struct thread *td, 132 struct file *fp) 133 { 134 135 return (pts_alloc(fflags & (FREAD|FWRITE), td, fp)); 136 } 137 138 static struct cdevsw ptmx_cdevsw = { 139 .d_version = D_VERSION, 140 .d_fdopen = ptmx_fdopen, 141 .d_name = "ptmx", 142 }; 143 144 static int 145 pty_modevent(module_t mod, int type, void *data) 146 { 147 148 switch(type) { 149 case MOD_LOAD: 150 EVENTHANDLER_REGISTER(dev_clone, pty_clone, 0, 1000); 151 make_dev_credf(MAKEDEV_ETERNAL_KLD, &ptmx_cdevsw, 0, NULL, 152 UID_ROOT, GID_WHEEL, 0666, "ptmx"); 153 break; 154 case MOD_SHUTDOWN: 155 break; 156 case MOD_UNLOAD: 157 /* XXX: No unloading support yet. */ 158 return (EBUSY); 159 default: 160 return (EOPNOTSUPP); 161 } 162 163 return (0); 164 } 165 166 DEV_MODULE(pty, pty_modevent, NULL); 167