1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2003 Poul-Henning Kamp. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 __FBSDID("$FreeBSD$"); 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/eventhandler.h> 34 #include <sys/conf.h> 35 #include <sys/kernel.h> 36 #include <sys/proc.h> 37 #include <sys/sx.h> 38 #include <sys/vnode.h> 39 40 #include <fs/devfs/devfs.h> 41 #include <fs/devfs/devfs_int.h> 42 43 static d_open_t cttyopen; 44 45 static struct cdevsw ctty_cdevsw = { 46 .d_version = D_VERSION, 47 .d_open = cttyopen, 48 .d_name = "ctty", 49 }; 50 51 static struct cdev *ctty; 52 53 static int 54 cttyopen(struct cdev *dev, int flag, int mode, struct thread *td) 55 { 56 57 return (ENXIO); 58 } 59 60 static void 61 ctty_clone(void *arg, struct ucred *cred, char *name, int namelen, 62 struct cdev **dev) 63 { 64 struct proc *p; 65 66 if (*dev != NULL) 67 return; 68 if (strcmp(name, "tty")) 69 return; 70 p = curproc; 71 sx_sunlock(&clone_drain_lock); 72 sx_slock(&proctree_lock); 73 sx_slock(&clone_drain_lock); 74 dev_lock(); 75 if (!(p->p_flag & P_CONTROLT)) 76 *dev = ctty; 77 else if (p->p_session->s_ttyvp == NULL) 78 *dev = ctty; 79 else if (p->p_session->s_ttyvp->v_type == VBAD || 80 p->p_session->s_ttyvp->v_rdev == NULL) { 81 /* e.g. s_ttyvp was revoked */ 82 *dev = ctty; 83 } else 84 *dev = p->p_session->s_ttyvp->v_rdev; 85 dev_refl(*dev); 86 dev_unlock(); 87 sx_sunlock(&proctree_lock); 88 } 89 90 static void 91 ctty_drvinit(void *unused) 92 { 93 94 EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000); 95 ctty = make_dev_credf(MAKEDEV_ETERNAL, &ctty_cdevsw, 0, NULL, UID_ROOT, 96 GID_WHEEL, 0666, "ctty"); 97 } 98 99 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL); 100