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 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 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 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 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