1 /* $NetBSD: tty_ptm.c,v 1.28 2012/10/19 16:55:22 apb 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 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: tty_ptm.c,v 1.28 2012/10/19 16:55:22 apb Exp $"); 31 32 #include "opt_compat_netbsd.h" 33 #include "opt_ptm.h" 34 35 /* pty multiplexor driver /dev/ptm{,x} */ 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/ioctl.h> 40 #include <sys/proc.h> 41 #include <sys/tty.h> 42 #include <sys/stat.h> 43 #include <sys/file.h> 44 #include <sys/uio.h> 45 #include <sys/kernel.h> 46 #include <sys/vnode.h> 47 #include <sys/namei.h> 48 #include <sys/signalvar.h> 49 #include <sys/filedesc.h> 50 #include <sys/conf.h> 51 #include <sys/poll.h> 52 #include <sys/pty.h> 53 #include <sys/kauth.h> 54 55 #include <miscfs/specfs/specdev.h> 56 57 #ifdef COMPAT_60 58 #include <compat/sys/ttycom.h> 59 #endif /* COMPAT_60 */ 60 61 #ifdef DEBUG_PTM 62 #define DPRINTF(a) printf a 63 #else 64 #define DPRINTF(a) 65 #endif 66 67 #ifdef NO_DEV_PTM 68 const struct cdevsw ptm_cdevsw = { 69 noopen, noclose, noread, nowrite, noioctl, 70 nostop, notty, nopoll, nommap, nokqfilter, D_TTY 71 }; 72 #else 73 74 static struct ptm_pty *ptm; 75 int pts_major, ptc_major; 76 77 static dev_t pty_getfree(void); 78 static int pty_alloc_master(struct lwp *, int *, dev_t *); 79 static int pty_alloc_slave(struct lwp *, int *, dev_t); 80 81 void ptmattach(int); 82 83 dev_t 84 pty_makedev(char ms, int minor) 85 { 86 return makedev(ms == 't' ? pts_major : ptc_major, minor); 87 } 88 89 90 static dev_t 91 pty_getfree(void) 92 { 93 extern kmutex_t pt_softc_mutex; 94 int i; 95 96 mutex_enter(&pt_softc_mutex); 97 for (i = 0; i < npty; i++) { 98 if (pty_isfree(i, 0)) 99 break; 100 } 101 mutex_exit(&pt_softc_mutex); 102 return pty_makedev('t', i); 103 } 104 105 /* 106 * Hacked up version of vn_open. We _only_ handle ptys and only open 107 * them with FREAD|FWRITE and never deal with creat or stuff like that. 108 * 109 * We need it because we have to fake up root credentials to open the pty. 110 */ 111 int 112 pty_vn_open(struct vnode *vp, struct lwp *l) 113 { 114 int error; 115 116 if (vp->v_type != VCHR) { 117 vput(vp); 118 return EINVAL; 119 } 120 121 error = VOP_OPEN(vp, FREAD|FWRITE, lwp0.l_cred); 122 123 if (error) { 124 vput(vp); 125 return error; 126 } 127 128 vp->v_writecount++; 129 130 return 0; 131 } 132 133 static int 134 pty_alloc_master(struct lwp *l, int *fd, dev_t *dev) 135 { 136 int error; 137 struct file *fp; 138 struct vnode *vp; 139 int md; 140 141 if ((error = fd_allocfile(&fp, fd)) != 0) { 142 DPRINTF(("fd_allocfile %d\n", error)); 143 return error; 144 } 145 retry: 146 /* Find and open a free master pty. */ 147 *dev = pty_getfree(); 148 md = minor(*dev); 149 if ((error = pty_check(md)) != 0) { 150 DPRINTF(("pty_check %d\n", error)); 151 goto bad; 152 } 153 if (ptm == NULL) { 154 DPRINTF(("no ptm\n")); 155 error = EOPNOTSUPP; 156 goto bad; 157 } 158 if ((error = (*ptm->allocvp)(ptm, l, &vp, *dev, 'p')) != 0) { 159 DPRINTF(("pty_allocvp %d\n", error)); 160 goto bad; 161 } 162 163 if ((error = pty_vn_open(vp, l)) != 0) { 164 DPRINTF(("pty_vn_open %d\n", error)); 165 /* 166 * Check if the master open failed because we lost 167 * the race to grab it. 168 */ 169 if (error != EIO) 170 goto bad; 171 error = !pty_isfree(md, 1); 172 DPRINTF(("pty_isfree %d\n", error)); 173 if (error) 174 goto retry; 175 else 176 goto bad; 177 } 178 fp->f_flag = FREAD|FWRITE; 179 fp->f_type = DTYPE_VNODE; 180 fp->f_ops = &vnops; 181 fp->f_data = vp; 182 VOP_UNLOCK(vp); 183 fd_affix(curproc, fp, *fd); 184 return 0; 185 bad: 186 fd_abort(curproc, fp, *fd); 187 return error; 188 } 189 190 int 191 pty_grant_slave(struct lwp *l, dev_t dev) 192 { 193 int error; 194 struct vnode *vp; 195 196 /* 197 * Open the slave. 198 * namei -> setattr -> unlock -> revoke -> vrele -> 199 * namei -> open -> unlock 200 * Three stage rocket: 201 * 1. Change the owner and permissions on the slave. 202 * 2. Revoke all the users of the slave. 203 * 3. open the slave. 204 */ 205 if (ptm == NULL) 206 return EOPNOTSUPP; 207 if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0) 208 return error; 209 210 if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) { 211 struct vattr vattr; 212 (*ptm->getvattr)(ptm, l, &vattr); 213 /* Do the VOP_SETATTR() as root. */ 214 error = VOP_SETATTR(vp, &vattr, lwp0.l_cred); 215 if (error) { 216 DPRINTF(("setattr %d\n", error)); 217 VOP_UNLOCK(vp); 218 vrele(vp); 219 return error; 220 } 221 } 222 VOP_UNLOCK(vp); 223 VOP_REVOKE(vp, REVOKEALL); 224 225 /* 226 * The vnode is useless after the revoke, we need to get it again. 227 */ 228 vrele(vp); 229 return 0; 230 } 231 232 static int 233 pty_alloc_slave(struct lwp *l, int *fd, dev_t dev) 234 { 235 int error; 236 struct file *fp; 237 struct vnode *vp; 238 239 /* Grab a filedescriptor for the slave */ 240 if ((error = fd_allocfile(&fp, fd)) != 0) { 241 DPRINTF(("fd_allocfile %d\n", error)); 242 return error; 243 } 244 245 if (ptm == NULL) { 246 error = EOPNOTSUPP; 247 goto bad; 248 } 249 250 if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0) 251 goto bad; 252 if ((error = pty_vn_open(vp, l)) != 0) 253 goto bad; 254 255 fp->f_flag = FREAD|FWRITE; 256 fp->f_type = DTYPE_VNODE; 257 fp->f_ops = &vnops; 258 fp->f_data = vp; 259 VOP_UNLOCK(vp); 260 fd_affix(curproc, fp, *fd); 261 return 0; 262 bad: 263 fd_abort(curproc, fp, *fd); 264 return error; 265 } 266 267 struct ptm_pty * 268 pty_sethandler(struct ptm_pty *nptm) 269 { 270 struct ptm_pty *optm = ptm; 271 ptm = nptm; 272 return optm; 273 } 274 275 int 276 pty_fill_ptmget(struct lwp *l, dev_t dev, int cfd, int sfd, void *data) 277 { 278 struct ptmget *ptmg = data; 279 int error; 280 281 if (ptm == NULL) 282 return EOPNOTSUPP; 283 284 ptmg->cfd = cfd == -1 ? minor(dev) : cfd; 285 ptmg->sfd = sfd == -1 ? minor(dev) : sfd; 286 287 error = (*ptm->makename)(ptm, l, ptmg->cn, sizeof(ptmg->cn), dev, 'p'); 288 if (error) 289 return error; 290 291 return (*ptm->makename)(ptm, l, ptmg->sn, sizeof(ptmg->sn), dev, 't'); 292 } 293 294 void 295 /*ARGSUSED*/ 296 ptmattach(int n) 297 { 298 extern const struct cdevsw pts_cdevsw, ptc_cdevsw; 299 /* find the major and minor of the pty devices */ 300 if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1) 301 panic("ptmattach: Can't find pty slave in cdevsw"); 302 if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1) 303 panic("ptmattach: Can't find pty master in cdevsw"); 304 #ifdef COMPAT_BSDPTY 305 ptm = &ptm_bsdpty; 306 #endif 307 } 308 309 static int 310 /*ARGSUSED*/ 311 ptmopen(dev_t dev, int flag, int mode, struct lwp *l) 312 { 313 int error; 314 int fd; 315 dev_t ttydev; 316 317 switch(minor(dev)) { 318 case 0: /* /dev/ptmx */ 319 case 2: /* /emul/linux/dev/ptmx */ 320 if ((error = pty_alloc_master(l, &fd, &ttydev)) != 0) 321 return error; 322 if (minor(dev) == 2) { 323 /* 324 * Linux ptyfs grants the pty right here. 325 * Handle this case here, instead of writing 326 * a new linux module. 327 */ 328 if ((error = pty_grant_slave(l, ttydev)) != 0) { 329 file_t *fp = fd_getfile(fd); 330 if (fp != NULL) { 331 fd_close(fd); 332 } 333 return error; 334 } 335 } 336 curlwp->l_dupfd = fd; 337 return EMOVEFD; 338 case 1: /* /dev/ptm */ 339 return 0; 340 default: 341 return ENODEV; 342 } 343 } 344 345 static int 346 /*ARGSUSED*/ 347 ptmclose(dev_t dev, int flag, int mode, struct lwp *l) 348 { 349 350 return (0); 351 } 352 353 static int 354 /*ARGSUSED*/ 355 ptmioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l) 356 { 357 int error; 358 dev_t newdev; 359 int cfd, sfd; 360 file_t *fp; 361 362 error = 0; 363 switch (cmd) { 364 case TIOCPTMGET: 365 if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0) 366 return error; 367 368 if ((error = pty_grant_slave(l, newdev)) != 0) 369 goto bad; 370 371 if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0) 372 goto bad; 373 374 /* now, put the indices and names into struct ptmget */ 375 return pty_fill_ptmget(l, newdev, cfd, sfd, data); 376 default: 377 #ifdef COMPAT_60 378 error = compat_60_ptmioctl(dev, cmd, data, flag, l); 379 if (error != EPASSTHROUGH) 380 return error; 381 #endif /* COMPAT_60 */ 382 DPRINTF(("ptmioctl EINVAL\n")); 383 return EINVAL; 384 } 385 bad: 386 fp = fd_getfile(cfd); 387 if (fp != NULL) { 388 fd_close(cfd); 389 } 390 return error; 391 } 392 393 const struct cdevsw ptm_cdevsw = { 394 ptmopen, ptmclose, noread, nowrite, ptmioctl, 395 nullstop, notty, nopoll, nommap, nokqfilter, D_TTY 396 }; 397 #endif 398