tty_ptm.c revision 1.3
1 /* $NetBSD: tty_ptm.c,v 1.3 2004/11/24 22:19:27 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2004 The NetBSD Foundation, Inc. 5 * 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 NetBSD 18 * Foundation, Inc. and its contributors. 19 * 4. Neither the name of The NetBSD Foundation nor the names of its 20 * contributors may be used to endorse or promote products derived 21 * from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 27 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33 * POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 __KERNEL_RCSID(0, "$NetBSD: tty_ptm.c,v 1.3 2004/11/24 22:19:27 christos Exp $"); 38 39 #include "opt_ptm.h" 40 41 /* pty multiplexor driver /dev/ptm{,x} */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/ioctl.h> 46 #include <sys/proc.h> 47 #include <sys/tty.h> 48 #include <sys/stat.h> 49 #include <sys/file.h> 50 #include <sys/uio.h> 51 #include <sys/kernel.h> 52 #include <sys/vnode.h> 53 #include <sys/namei.h> 54 #include <sys/signalvar.h> 55 #include <sys/uio.h> 56 #include <sys/filedesc.h> 57 #include <sys/conf.h> 58 #include <sys/poll.h> 59 #include <sys/malloc.h> 60 #include <sys/pty.h> 61 62 #ifdef DEBUG_PTM 63 #define DPRINTF(a) printf a 64 #else 65 #define DPRINTF(a) 66 #endif 67 68 #ifdef NO_DEV_PTM 69 const struct cdevsw ptm_cdevsw = { 70 noopen, noclose, noread, nowrite, noioctl, 71 nostop, notty, nopoll, nommap, nokqfilter, D_TTY 72 }; 73 #else 74 75 static struct ptm_pty *ptm; 76 int pts_major, ptc_major; 77 78 static dev_t pty_getfree(void); 79 static int pty_alloc_master(struct proc *, int *, dev_t *); 80 static int pty_alloc_slave(struct proc *, int *, dev_t); 81 82 void ptmattach(int); 83 84 dev_type_open(ptmopen); 85 dev_type_close(ptmclose); 86 dev_type_ioctl(ptmioctl); 87 88 const struct cdevsw ptm_cdevsw = { 89 ptmopen, ptmclose, noread, nowrite, ptmioctl, 90 nullstop, notty, nopoll, nommap, nokqfilter, D_TTY 91 }; 92 93 dev_t 94 pty_makedev(char ms, int minor) 95 { 96 return makedev(ms == 't' ? pts_major : ptc_major, minor); 97 } 98 99 static dev_t 100 pty_getfree(void) 101 { 102 extern struct simplelock pt_softc_mutex; 103 int i; 104 105 simple_lock(&pt_softc_mutex); 106 for (i = 0; i < npty; i++) { 107 if (pty_isfree(i, 0)) 108 break; 109 } 110 simple_unlock(&pt_softc_mutex); 111 return pty_makedev('t', i); 112 } 113 114 /* 115 * Hacked up version of vn_open. We _only_ handle ptys and only open 116 * them with FREAD|FWRITE and never deal with creat or stuff like that. 117 * 118 * We need it because we have to fake up root credentials to open the pty. 119 */ 120 int 121 pty_vn_open(struct vnode *vp, struct proc *p) 122 { 123 struct ucred *cred; 124 int error; 125 126 if (vp->v_type != VCHR) { 127 vput(vp); 128 return EINVAL; 129 } 130 131 /* 132 * Get us a fresh cred with root privileges. 133 */ 134 cred = crget(); 135 error = VOP_OPEN(vp, FREAD|FWRITE, cred, p); 136 crfree(cred); 137 138 if (error) { 139 vput(vp); 140 return error; 141 } 142 143 vp->v_writecount++; 144 145 return 0; 146 } 147 148 static int 149 pty_alloc_master(struct proc *p, int *fd, dev_t *dev) 150 { 151 int error; 152 struct file *fp; 153 struct vnode *vp; 154 int md; 155 156 if ((error = falloc(p, &fp, fd)) != 0) { 157 DPRINTF(("falloc %d\n", error)); 158 return error; 159 } 160 retry: 161 /* Find and open a free master pty. */ 162 *dev = pty_getfree(); 163 md = minor(*dev); 164 if ((error = pty_check(md)) != 0) { 165 DPRINTF(("pty_check %d\n", error)); 166 goto bad; 167 } 168 if (ptm == NULL) { 169 error = EOPNOTSUPP; 170 goto bad; 171 } 172 if ((error = (*ptm->allocvp)(ptm, p, &vp, *dev, 'p')) != 0) 173 goto bad; 174 175 if ((error = pty_vn_open(vp, p)) != 0) { 176 /* 177 * Check if the master open failed because we lost 178 * the race to grab it. 179 */ 180 if (error != EIO) 181 goto bad; 182 error = !pty_isfree(md, 1); 183 if (error) 184 goto retry; 185 else 186 goto bad; 187 } 188 fp->f_flag = FREAD|FWRITE; 189 fp->f_type = DTYPE_VNODE; 190 fp->f_ops = &vnops; 191 fp->f_data = vp; 192 VOP_UNLOCK(vp, 0); 193 FILE_SET_MATURE(fp); 194 FILE_UNUSE(fp, p); 195 return 0; 196 bad: 197 FILE_UNUSE(fp, p); 198 fdremove(p->p_fd, *fd); 199 ffree(fp); 200 return error; 201 } 202 203 int 204 pty_grant_slave(struct proc *p, dev_t dev) 205 { 206 int error; 207 struct vnode *vp; 208 209 /* 210 * Open the slave. 211 * namei -> setattr -> unlock -> revoke -> vrele -> 212 * namei -> open -> unlock 213 * Three stage rocket: 214 * 1. Change the owner and permissions on the slave. 215 * 2. Revoke all the users of the slave. 216 * 3. open the slave. 217 */ 218 if (ptm == NULL) 219 return EOPNOTSUPP; 220 221 if ((error = (*ptm->allocvp)(ptm, p, &vp, dev, 't')) != 0) 222 return error; 223 224 if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) { 225 struct vattr vattr; 226 struct ucred *cred; 227 (*ptm->getvattr)(ptm, p, &vattr); 228 /* Get a fake cred to pretend we're root. */ 229 cred = crget(); 230 error = VOP_SETATTR(vp, &vattr, cred, p); 231 crfree(cred); 232 if (error) { 233 DPRINTF(("setattr %d\n", error)); 234 VOP_UNLOCK(vp, 0); 235 vrele(vp); 236 return error; 237 } 238 } 239 VOP_UNLOCK(vp, 0); 240 if (vp->v_usecount > 1 || 241 (vp->v_flag & (VALIASED | VLAYER))) 242 VOP_REVOKE(vp, REVOKEALL); 243 244 /* 245 * The vnode is useless after the revoke, we need to get it again. 246 */ 247 vrele(vp); 248 return 0; 249 } 250 251 static int 252 pty_alloc_slave(struct proc *p, int *fd, dev_t dev) 253 { 254 int error; 255 struct file *fp; 256 struct vnode *vp; 257 258 /* Grab a filedescriptor for the slave */ 259 if ((error = falloc(p, &fp, fd)) != 0) { 260 DPRINTF(("falloc %d\n", error)); 261 return error; 262 } 263 264 if (ptm == NULL) { 265 error = EOPNOTSUPP; 266 goto bad; 267 } 268 269 if ((error = (*ptm->allocvp)(ptm, p, &vp, dev, 't')) != 0) 270 goto bad; 271 if ((error = pty_vn_open(vp, p)) != 0) 272 goto bad; 273 274 fp->f_flag = FREAD|FWRITE; 275 fp->f_type = DTYPE_VNODE; 276 fp->f_ops = &vnops; 277 fp->f_data = vp; 278 VOP_UNLOCK(vp, 0); 279 FILE_SET_MATURE(fp); 280 FILE_UNUSE(fp, p); 281 return 0; 282 bad: 283 FILE_UNUSE(fp, p); 284 fdremove(p->p_fd, *fd); 285 ffree(fp); 286 return error; 287 } 288 289 struct ptm_pty * 290 pty_sethandler(struct ptm_pty *nptm) 291 { 292 struct ptm_pty *optm = ptm; 293 ptm = nptm; 294 return optm; 295 } 296 297 int 298 pty_fill_ptmget(dev_t dev, int cfd, int sfd, void *data) 299 { 300 struct ptmget *ptmg = data; 301 int error; 302 303 if (ptm == NULL) 304 return EOPNOTSUPP; 305 306 ptmg->cfd = cfd == -1 ? minor(dev) : cfd; 307 ptmg->sfd = sfd == -1 ? minor(dev) : sfd; 308 309 error = (*ptm->makename)(ptm, ptmg->cn, sizeof(ptmg->cn), dev, 'p'); 310 if (error) 311 return error; 312 313 return (*ptm->makename)(ptm, ptmg->sn, sizeof(ptmg->sn), dev, 't'); 314 } 315 316 void 317 /*ARGSUSED*/ 318 ptmattach(int n) 319 { 320 extern const struct cdevsw pts_cdevsw, ptc_cdevsw; 321 /* find the major and minor of the pty devices */ 322 if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1) 323 panic("ptmattach: Can't find pty slave in cdevsw"); 324 if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1) 325 panic("ptmattach: Can't find pty master in cdevsw"); 326 #ifdef COMPAT_BSDPTY 327 ptm = &ptm_bsdpty; 328 #endif 329 } 330 331 int 332 /*ARGSUSED*/ 333 ptmopen(dev_t dev, int flag, int mode, struct proc *p) 334 { 335 int error; 336 int fd; 337 338 switch(minor(dev)) { 339 case 0: /* /dev/ptmx */ 340 if ((error = pty_alloc_master(p, &fd, &dev)) != 0) 341 return error; 342 curlwp->l_dupfd = fd; 343 return ENXIO; 344 case 1: /* /dev/ptm */ 345 return 0; 346 default: 347 return ENODEV; 348 } 349 } 350 351 int 352 /*ARGSUSED*/ 353 ptmclose(dev_t dev, int flag, int mode, struct proc *p) 354 { 355 return (0); 356 } 357 358 int 359 /*ARGSUSED*/ 360 ptmioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p) 361 { 362 int error; 363 dev_t newdev; 364 int cfd, sfd; 365 struct file *fp; 366 367 error = 0; 368 switch (cmd) { 369 case TIOCPTMGET: 370 if ((error = pty_alloc_master(p, &cfd, &newdev)) != 0) 371 return error; 372 373 if ((error = pty_grant_slave(p, newdev)) != 0) 374 goto bad; 375 376 if ((error = pty_alloc_slave(p, &sfd, newdev)) != 0) 377 goto bad; 378 379 /* now, put the indices and names into struct ptmget */ 380 return pty_fill_ptmget(newdev, cfd, sfd, data); 381 default: 382 DPRINTF(("ptmioctl EINVAL\n")); 383 return EINVAL; 384 } 385 bad: 386 fp = fd_getfile(p->p_fd, cfd); 387 fdremove(p->p_fd, cfd); 388 ffree(fp); 389 return error; 390 } 391 #endif 392
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