| 1 | /*- |
| 2 | * (MPSAFE) |
| 3 | * |
| 4 | * Copyright (c) 1982, 1986, 1991, 1993 |
| 5 | * The Regents of the University of California. All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * 3. All advertising materials mentioning features or use of this software |
| 16 | * must display the following acknowledgement: |
| 17 | * This product includes software developed by the University of |
| 18 | * California, Berkeley and its contributors. |
| 19 | * 4. Neither the name of the University nor the names of its contributors |
| 20 | * may be used to endorse or promote products derived from this software |
| 21 | * without specific prior written permission. |
| 22 | * |
| 23 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 24 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 25 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 26 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 27 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 28 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 29 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 30 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 31 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 32 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 33 | * SUCH DAMAGE. |
| 34 | * |
| 35 | * @(#)tty_tty.c 8.2 (Berkeley) 9/23/93 |
| 36 | * $FreeBSD: src/sys/kern/tty_tty.c,v 1.30 1999/09/25 18:24:24 phk Exp $ |
| 37 | */ |
| 38 | |
| 39 | /* |
| 40 | * Indirect driver for controlling tty. |
| 41 | */ |
| 42 | |
| 43 | #include <sys/param.h> |
| 44 | #include <sys/systm.h> |
| 45 | #include <sys/conf.h> |
| 46 | #include <sys/device.h> |
| 47 | #include <sys/lock.h> |
| 48 | #include <sys/fcntl.h> |
| 49 | #include <sys/proc.h> |
| 50 | #include <sys/ttycom.h> |
| 51 | #include <sys/vnode.h> |
| 52 | #include <sys/kernel.h> |
| 53 | #include <sys/poll.h> /* XXX: poll args used in KQ filters */ |
| 54 | #include <sys/event.h> |
| 55 | |
| 56 | static d_open_t cttyopen; |
| 57 | static d_close_t cttyclose; |
| 58 | static d_read_t cttyread; |
| 59 | static d_write_t cttywrite; |
| 60 | static d_ioctl_t cttyioctl; |
| 61 | static d_kqfilter_t cttykqfilter; |
| 62 | |
| 63 | static void cttyfilt_detach(struct knote *); |
| 64 | static int cttyfilt_read(struct knote *, long); |
| 65 | static int cttyfilt_write(struct knote *, long); |
| 66 | |
| 67 | #define CDEV_MAJOR 1 |
| 68 | static struct dev_ops ctty_ops = { |
| 69 | { "ctty", 0, D_TTY }, |
| 70 | .d_open = cttyopen, |
| 71 | .d_close = cttyclose, |
| 72 | .d_read = cttyread, |
| 73 | .d_write = cttywrite, |
| 74 | .d_ioctl = cttyioctl, |
| 75 | .d_kqfilter = cttykqfilter |
| 76 | }; |
| 77 | |
| 78 | #define cttyvp(p) (((p)->p_flags & P_CONTROLT) ? \ |
| 79 | (p)->p_session->s_ttyvp : NULL) |
| 80 | |
| 81 | /* |
| 82 | * This opens /dev/tty. Because multiple opens of /dev/tty only |
| 83 | * generate a single open to the actual tty, the file modes are |
| 84 | * locked to FREAD|FWRITE. |
| 85 | */ |
| 86 | static int |
| 87 | cttyopen(struct dev_open_args *ap) |
| 88 | { |
| 89 | struct proc *p = curproc; |
| 90 | struct vnode *ttyvp; |
| 91 | int error; |
| 92 | |
| 93 | KKASSERT(p); |
| 94 | retry: |
| 95 | if ((ttyvp = cttyvp(p)) == NULL) |
| 96 | return (ENXIO); |
| 97 | if (ttyvp->v_flag & VCTTYISOPEN) |
| 98 | return (0); |
| 99 | |
| 100 | /* |
| 101 | * Messy interlock, don't let the vnode go away while we try to |
| 102 | * lock it and check for race after we might have blocked. |
| 103 | */ |
| 104 | vhold(ttyvp); |
| 105 | vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY); |
| 106 | if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN)) { |
| 107 | kprintf("Warning: cttyopen: race avoided\n"); |
| 108 | vn_unlock(ttyvp); |
| 109 | vdrop(ttyvp); |
| 110 | goto retry; |
| 111 | } |
| 112 | vsetflags(ttyvp, VCTTYISOPEN); |
| 113 | error = VOP_OPEN(ttyvp, FREAD|FWRITE, ap->a_cred, NULL); |
| 114 | if (error) |
| 115 | vclrflags(ttyvp, VCTTYISOPEN); |
| 116 | vn_unlock(ttyvp); |
| 117 | vdrop(ttyvp); |
| 118 | return(error); |
| 119 | } |
| 120 | |
| 121 | /* |
| 122 | * This closes /dev/tty. Because multiple opens of /dev/tty only |
| 123 | * generate a single open to the actual tty, the file modes are |
| 124 | * locked to FREAD|FWRITE. |
| 125 | */ |
| 126 | static int |
| 127 | cttyclose(struct dev_close_args *ap) |
| 128 | { |
| 129 | struct proc *p = curproc; |
| 130 | struct vnode *ttyvp; |
| 131 | int error; |
| 132 | |
| 133 | KKASSERT(p); |
| 134 | retry: |
| 135 | /* |
| 136 | * The tty may have been TIOCNOTTY'd, don't return an |
| 137 | * error on close. We just have nothing to do. |
| 138 | */ |
| 139 | if ((ttyvp = cttyvp(p)) == NULL) |
| 140 | return(0); |
| 141 | if (ttyvp->v_flag & VCTTYISOPEN) { |
| 142 | /* |
| 143 | * Avoid a nasty race if we block while getting the lock. |
| 144 | */ |
| 145 | vref(ttyvp); |
| 146 | error = vn_lock(ttyvp, LK_EXCLUSIVE | LK_RETRY); |
| 147 | if (error) { |
| 148 | vrele(ttyvp); |
| 149 | goto retry; |
| 150 | } |
| 151 | if (ttyvp != cttyvp(p) || (ttyvp->v_flag & VCTTYISOPEN) == 0) { |
| 152 | kprintf("Warning: cttyclose: race avoided\n"); |
| 153 | vn_unlock(ttyvp); |
| 154 | vrele(ttyvp); |
| 155 | goto retry; |
| 156 | } |
| 157 | vclrflags(ttyvp, VCTTYISOPEN); |
| 158 | error = VOP_CLOSE(ttyvp, FREAD|FWRITE); |
| 159 | vn_unlock(ttyvp); |
| 160 | vrele(ttyvp); |
| 161 | } else { |
| 162 | error = 0; |
| 163 | } |
| 164 | return(error); |
| 165 | } |
| 166 | |
| 167 | /* |
| 168 | * Read from the controlling terminal (/dev/tty). The tty is refed as |
| 169 | * of the cttyvp(), but the ref can get ripped out from under us if |
| 170 | * the controlling terminal is revoked while we are blocked on the lock, |
| 171 | * so use vget() instead of vn_lock(). |
| 172 | */ |
| 173 | static int |
| 174 | cttyread(struct dev_read_args *ap) |
| 175 | { |
| 176 | struct proc *p = curproc; |
| 177 | struct vnode *ttyvp; |
| 178 | int error; |
| 179 | |
| 180 | KKASSERT(p); |
| 181 | ttyvp = cttyvp(p); |
| 182 | if (ttyvp == NULL) |
| 183 | return (EIO); |
| 184 | if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) { |
| 185 | error = VOP_READ(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED); |
| 186 | vput(ttyvp); |
| 187 | } |
| 188 | return (error); |
| 189 | } |
| 190 | |
| 191 | /* |
| 192 | * Read from the controlling terminal (/dev/tty). The tty is refed as |
| 193 | * of the cttyvp(), but the ref can get ripped out from under us if |
| 194 | * the controlling terminal is revoked while we are blocked on the lock, |
| 195 | * so use vget() instead of vn_lock(). |
| 196 | */ |
| 197 | static int |
| 198 | cttywrite(struct dev_write_args *ap) |
| 199 | { |
| 200 | struct proc *p = curproc; |
| 201 | struct vnode *ttyvp; |
| 202 | int error; |
| 203 | |
| 204 | KKASSERT(p); |
| 205 | ttyvp = cttyvp(p); |
| 206 | if (ttyvp == NULL) |
| 207 | return (EIO); |
| 208 | if ((error = vget(ttyvp, LK_EXCLUSIVE | LK_RETRY)) == 0) { |
| 209 | error = VOP_WRITE(ttyvp, ap->a_uio, ap->a_ioflag, NOCRED); |
| 210 | vput(ttyvp); |
| 211 | } |
| 212 | return (error); |
| 213 | } |
| 214 | |
| 215 | /*ARGSUSED*/ |
| 216 | static int |
| 217 | cttyioctl(struct dev_ioctl_args *ap) |
| 218 | { |
| 219 | struct vnode *ttyvp; |
| 220 | struct proc *p = curproc; |
| 221 | |
| 222 | KKASSERT(p); |
| 223 | lwkt_gettoken(&p->p_token); |
| 224 | lwkt_gettoken(&proc_token); |
| 225 | ttyvp = cttyvp(p); |
| 226 | if (ttyvp == NULL) { |
| 227 | lwkt_reltoken(&proc_token); |
| 228 | lwkt_reltoken(&p->p_token); |
| 229 | return (EIO); |
| 230 | } |
| 231 | /* |
| 232 | * Don't allow controlling tty to be set to the controlling tty |
| 233 | * (infinite recursion). |
| 234 | */ |
| 235 | if (ap->a_cmd == TIOCSCTTY) { |
| 236 | lwkt_reltoken(&proc_token); |
| 237 | lwkt_reltoken(&p->p_token); |
| 238 | return EINVAL; |
| 239 | } |
| 240 | if (ap->a_cmd == TIOCNOTTY) { |
| 241 | if (!SESS_LEADER(p)) { |
| 242 | p->p_flags &= ~P_CONTROLT; |
| 243 | lwkt_reltoken(&proc_token); |
| 244 | lwkt_reltoken(&p->p_token); |
| 245 | return (0); |
| 246 | } else { |
| 247 | lwkt_reltoken(&proc_token); |
| 248 | lwkt_reltoken(&p->p_token); |
| 249 | return (EINVAL); |
| 250 | } |
| 251 | } |
| 252 | lwkt_reltoken(&proc_token); |
| 253 | lwkt_reltoken(&p->p_token); |
| 254 | |
| 255 | return (VOP_IOCTL(ttyvp, ap->a_cmd, ap->a_data, ap->a_fflag, |
| 256 | ap->a_cred, ap->a_sysmsg)); |
| 257 | } |
| 258 | |
| 259 | static struct filterops cttyfiltops_read = |
| 260 | { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_read }; |
| 261 | static struct filterops cttyfiltops_write = |
| 262 | { FILTEROP_ISFD, NULL, cttyfilt_detach, cttyfilt_write }; |
| 263 | |
| 264 | static int |
| 265 | cttykqfilter(struct dev_kqfilter_args *ap) |
| 266 | { |
| 267 | cdev_t dev = ap->a_head.a_dev; |
| 268 | struct proc *p = curproc; |
| 269 | struct knote *kn = ap->a_kn; |
| 270 | struct vnode *ttyvp; |
| 271 | |
| 272 | KKASSERT(p); |
| 273 | ttyvp = cttyvp(p); |
| 274 | |
| 275 | if (ttyvp != NULL) |
| 276 | return (VOP_KQFILTER(ttyvp, kn)); |
| 277 | |
| 278 | ap->a_result = 0; |
| 279 | |
| 280 | switch (kn->kn_filter) { |
| 281 | case EVFILT_READ: |
| 282 | kn->kn_fop = &cttyfiltops_read; |
| 283 | kn->kn_hook = (caddr_t)dev; |
| 284 | break; |
| 285 | case EVFILT_WRITE: |
| 286 | kn->kn_fop = &cttyfiltops_write; |
| 287 | kn->kn_hook = (caddr_t)dev; |
| 288 | break; |
| 289 | default: |
| 290 | ap->a_result = EOPNOTSUPP; |
| 291 | return (0); |
| 292 | } |
| 293 | |
| 294 | return (0); |
| 295 | } |
| 296 | |
| 297 | static void |
| 298 | cttyfilt_detach(struct knote *kn) {} |
| 299 | |
| 300 | static int |
| 301 | cttyfilt_read(struct knote *kn, long hint) |
| 302 | { |
| 303 | cdev_t dev = (cdev_t)kn->kn_hook; |
| 304 | |
| 305 | if (seltrue(dev, POLLIN | POLLRDNORM)) |
| 306 | return (1); |
| 307 | |
| 308 | return (0); |
| 309 | } |
| 310 | |
| 311 | static int |
| 312 | cttyfilt_write(struct knote *kn, long hint) |
| 313 | { |
| 314 | cdev_t dev = (cdev_t)kn->kn_hook; |
| 315 | |
| 316 | if (seltrue(dev, POLLOUT | POLLWRNORM)) |
| 317 | return (1); |
| 318 | |
| 319 | return (0); |
| 320 | } |
| 321 | |
| 322 | static void |
| 323 | ctty_drvinit(void *unused __unused) |
| 324 | { |
| 325 | make_dev(&ctty_ops, 0, 0, 0, 0666, "tty"); |
| 326 | } |
| 327 | |
| 328 | SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,ctty_drvinit,NULL) |