1 /*- 2 * Copyright (c) 1982, 1986, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)tty_tty.c 8.2 (Berkeley) 9/23/93 34 * $FreeBSD: src/sys/kern/tty_tty.c,v 1.30 1999/09/25 18:24:24 phk Exp $ 35 * $DragonFly: src/sys/kern/tty_tty.c,v 1.19 2007/07/03 17:22:14 dillon Exp $ 36 */ 37 38 /* 39 * Indirect driver for controlling tty. 40 */ 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/conf.h> 45 #include <sys/device.h> 46 #include <sys/lock.h> 47 #include <sys/fcntl.h> 48 #include <sys/proc.h> 49 #include <sys/ttycom.h> 50 #include <sys/vnode.h> 51 #include <sys/kernel.h> 52 53 static d_open_t cttyopen; 54 static d_close_t cttyclose; 55 static d_read_t cttyread; 56 static d_write_t cttywrite; 57 static d_ioctl_t cttyioctl; 58 static d_poll_t cttypoll; 59 60 #define CDEV_MAJOR 1 61 /* Don't make this static, since fdesc_vnops uses it. */ 62 struct dev_ops ctty_ops = { 63 { "ctty", CDEV_MAJOR, D_TTY }, 64 .d_open = cttyopen, 65 .d_close = cttyclose, 66 .d_read = cttyread, 67 .d_write = cttywrite, 68 .d_ioctl = cttyioctl, 69 .d_poll = cttypoll, 70 }; 71 72 #define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL) 73 74 /* 75 * This opens /dev/tty. Because multiple opens of /dev/tty only 76 * generate a single open to the actual tty, the file modes are 77 * locked to FREAD|FWRITE. 78 */ 79 static int 80 cttyopen(struct dev_open_args *ap) 81 { 82 struct proc *p = curproc; 83 struct vnode *ttyvp; 84 int error; 85 86 KKASSERT(p); 87 retry: 88 if ((ttyvp = cttyvp(p)) == NULL) 89 return (ENXIO); 90 if (ttyvp->v_flag & VCTTYISOPEN) 91 return (0); 92 93 /* 94 * Messy interlock, don't let the vnode go away while we try to 95 * lock it and check for race after we might have blocked. 96 */ 97 vhold(ttyvp); 98 vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY); 99 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN)) { 100 kprintf("Warning: cttyopen: race avoided\n"); 101 vn_unlock(ttyvp); 102 vdrop(ttyvp); 103 goto retry; 104 } 105 vsetflags(ttyvp, VCTTYISOPEN); 106 error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL); 107 if (error) 108 vclrflags(ttyvp, VCTTYISOPEN); 109 vn_unlock(ttyvp); 110 vdrop(ttyvp); 111 return(error); 112 } 113 114 /* 115 * This closes /dev/tty. Because multiple opens of /dev/tty only 116 * generate a single open to the actual tty, the file modes are 117 * locked to FREAD|FWRITE. 118 */ 119 static int 120 cttyclose(struct dev_close_args *ap) 121 { 122 struct proc *p = curproc; 123 struct vnode *ttyvp; 124 int error; 125 126 KKASSERT(p); 127 retry: 128 /* 129 * The tty may have been TIOCNOTTY'd, don't return an 130 * error on close. We just have nothing to do. 131 */ 132 if ((ttyvp = cttyvp(p)) == NULL) 133 return(0); 134 if (ttyvp->v_flag & VCTTYISOPEN) { 135 /* 136 * Avoid a nasty race if we block while getting the lock. 137 */ 138 vref(ttyvp); 139 error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY); 140 if (error) { 141 vrele(ttyvp); 142 goto retry; 143 } 144 if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN) == 0) { 145 kprintf("Warning: cttyclose: race avoided\n"); 146 vn_unlock(ttyvp); 147 vrele(ttyvp); 148 goto retry; 149 } 150 vclrflags(ttyvp, VCTTYISOPEN); 151 error = VOP_CLOSE(ttyvp, FREAD|FWRITE); 152 vn_unlock(ttyvp); 153 vrele(ttyvp); 154 } else { 155 error = 0; 156 } 157 return(error); 158 } 159 160 /* 161 * Read from the controlling terminal (/dev/tty). The tty is refed as 162 * of the cttyvp(), but the ref can get ripped out from under us if 163 * the controlling terminal is revoked while we are blocked on the lock, 164 * so use vget() instead of vn_lock(). 165 */ 166 static int 167 cttyread(struct dev_read_args *ap) 168 { 169 struct proc *p = curproc; 170 struct vnode *ttyvp; 171 int error; 172 173 KKASSERT(p); 174 ttyvp = cttyvp(p); 175 if (ttyvp == NULL) 176 return (EIO); 177 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) { 178 error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED); 179 vput(ttyvp); 180 } 181 return (error); 182 } 183 184 /* 185 * Read from the controlling terminal (/dev/tty). The tty is refed as 186 * of the cttyvp(), but the ref can get ripped out from under us if 187 * the controlling terminal is revoked while we are blocked on the lock, 188 * so use vget() instead of vn_lock(). 189 */ 190 static int 191 cttywrite(struct dev_write_args *ap) 192 { 193 struct proc *p = curproc; 194 struct vnode *ttyvp; 195 int error; 196 197 KKASSERT(p); 198 ttyvp = cttyvp(p); 199 if (ttyvp == NULL) 200 return (EIO); 201 if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) { 202 error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED); 203 vput(ttyvp); 204 } 205 return (error); 206 } 207 208 /*ARGSUSED*/ 209 static int 210 cttyioctl(struct dev_ioctl_args *ap) 211 { 212 struct vnode *ttyvp; 213 struct proc *p = curproc; 214 215 KKASSERT(p); 216 ttyvp = cttyvp(p); 217 if (ttyvp == NULL) 218 return (EIO); 219 /* 220 * Don't allow controlling tty to be set to the controlling tty 221 * (infinite recursion). 222 */ 223 if (ap->a_cmd == TIOCSCTTY) 224 return EINVAL; 225 if (ap->a_cmd == TIOCNOTTY) { 226 if (!SESS_LEADER(p)) { 227 p->p_flag &= ~P_CONTROLT; 228 return (0); 229 } else { 230 return (EINVAL); 231 } 232 } 233 return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag, ap->a_cred)); 234 } 235 236 /*ARGSUSED*/ 237 static int 238 cttypoll(struct dev_poll_args *ap) 239 { 240 cdev_t dev = ap->a_head.a_dev; 241 struct vnode *ttyvp; 242 struct proc *p = curproc; 243 244 KKASSERT(p); 245 ttyvp = cttyvp(p); 246 /* 247 * try operation to get EOF/failure 248 */ 249 if (ttyvp == NULL) 250 ap->a_events = seltrue(dev, ap->a_events); 251 else 252 ap->a_events = VOP_POLL(ttyvp, ap->a_events, p->p_ucred); 253 return(0); 254 } 255 256 static void 257 ctty_drvinit(void *unused __unused) 258 { 259 dev_ops_add(&ctty_ops, 0, 0); 260 make_dev(&ctty_ops, 0, 0, 0, 0666, "tty"); 261 } 262 263 SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL) 264