tty_ptm.c revision 1.2.2.2
1 /* $NetBSD: tty_ptm.c,v 1.2.2.2 2004/11/14 08:15:57 skrll 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 1.2.2.2 2004/11/14 08:15:57 skrll 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 lwp *, int *, dev_t *); 80 static int pty_alloc_slave(struct lwp *, 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 lwp *l) 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, l); 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 lwp *l, int *fd, dev_t *dev) 150 { 151 int error; 152 struct file *fp; 153 struct vnode *vp; 154 struct proc *p = l->l_proc; 155 int md; 156 157 if ((error = falloc(p, &fp, fd)) != 0) { 158 DPRINTF(("falloc %d\n", error)); 159 return error; 160 } 161 retry: 162 /* Find and open a free master pty. */ 163 *dev = pty_getfree(); 164 md = minor(*dev); 165 if ((error = pty_check(md)) != 0) { 166 DPRINTF(("pty_check %d\n", error)); 167 goto bad; 168 } 169 if (ptm == NULL) { 170 error = EOPNOTSUPP; 171 goto bad; 172 } 173 if ((error = (*ptm->allocvp)(ptm, l, &vp, *dev, 'p')) != 0) 174 goto bad; 175 176 if ((error = pty_vn_open(vp, l)) != 0) { 177 /* 178 * Check if the master open failed because we lost 179 * the race to grab it. 180 */ 181 if (error != EIO) 182 goto bad; 183 error = !pty_isfree(md, 1); 184 if (error) 185 goto retry; 186 else 187 goto bad; 188 } 189 fp->f_flag = FREAD|FWRITE; 190 fp->f_type = DTYPE_VNODE; 191 fp->f_ops = &vnops; 192 fp->f_data = vp; 193 VOP_UNLOCK(vp, 0); 194 FILE_SET_MATURE(fp); 195 FILE_UNUSE(fp, l); 196 return 0; 197 bad: 198 FILE_UNUSE(fp, l); 199 fdremove(p->p_fd, *fd); 200 ffree(fp); 201 return error; 202 } 203 204 int 205 pty_grant_slave(struct lwp *l, dev_t dev) 206 { 207 int error; 208 struct vnode *vp; 209 210 /* 211 * Open the slave. 212 * namei -> setattr -> unlock -> revoke -> vrele -> 213 * namei -> open -> unlock 214 * Three stage rocket: 215 * 1. Change the owner and permissions on the slave. 216 * 2. Revoke all the users of the slave. 217 * 3. open the slave. 218 */ 219 if (ptm == NULL) 220 return EOPNOTSUPP; 221 222 if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0) 223 return error; 224 225 if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) { 226 struct vattr vattr; 227 struct ucred *cred; 228 /* get real uid */ 229 VATTR_NULL(&vattr); 230 vattr.va_uid = l->l_proc->p_cred->p_ruid; 231 vattr.va_gid = _TTY_GID; 232 vattr.va_mode = S_IRUSR|S_IWUSR|S_IWGRP; 233 /* Get a fake cred to pretend we're root. */ 234 cred = crget(); 235 error = VOP_SETATTR(vp, &vattr, cred, l); 236 crfree(cred); 237 if (error) { 238 DPRINTF(("setattr %d\n", error)); 239 VOP_UNLOCK(vp, 0); 240 vrele(vp); 241 return error; 242 } 243 } 244 VOP_UNLOCK(vp, 0); 245 if (vp->v_usecount > 1 || 246 (vp->v_flag & (VALIASED | VLAYER))) 247 VOP_REVOKE(vp, REVOKEALL); 248 249 /* 250 * The vnode is useless after the revoke, we need to get it again. 251 */ 252 vrele(vp); 253 return 0; 254 } 255 256 static int 257 pty_alloc_slave(struct lwp *l, int *fd, dev_t dev) 258 { 259 int error; 260 struct file *fp; 261 struct vnode *vp; 262 struct proc *p = l->l_proc; 263 264 /* Grab a filedescriptor for the slave */ 265 if ((error = falloc(p, &fp, fd)) != 0) { 266 DPRINTF(("falloc %d\n", error)); 267 return error; 268 } 269 270 if (ptm == NULL) { 271 error = EOPNOTSUPP; 272 goto bad; 273 } 274 275 if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0) 276 goto bad; 277 if ((error = pty_vn_open(vp, l)) != 0) 278 goto bad; 279 280 fp->f_flag = FREAD|FWRITE; 281 fp->f_type = DTYPE_VNODE; 282 fp->f_ops = &vnops; 283 fp->f_data = vp; 284 VOP_UNLOCK(vp, 0); 285 FILE_SET_MATURE(fp); 286 FILE_UNUSE(fp, l); 287 return 0; 288 bad: 289 FILE_UNUSE(fp, l); 290 fdremove(p->p_fd, *fd); 291 ffree(fp); 292 return error; 293 } 294 295 struct ptm_pty * 296 pty_sethandler(struct ptm_pty *nptm) 297 { 298 struct ptm_pty *optm = ptm; 299 ptm = nptm; 300 return optm; 301 } 302 303 int 304 pty_fill_ptmget(dev_t dev, int cfd, int sfd, void *data) 305 { 306 struct ptmget *ptmg = data; 307 int error; 308 309 if (ptm == NULL) 310 return EOPNOTSUPP; 311 312 ptmg->cfd = cfd == -1 ? minor(dev) : cfd; 313 ptmg->sfd = sfd == -1 ? minor(dev) : sfd; 314 315 error = (*ptm->makename)(ptm, ptmg->cn, sizeof(ptmg->cn), dev, 'p'); 316 if (error) 317 return error; 318 319 return (*ptm->makename)(ptm, ptmg->sn, sizeof(ptmg->sn), dev, 't'); 320 } 321 322 void 323 /*ARGSUSED*/ 324 ptmattach(int n) 325 { 326 extern const struct cdevsw pts_cdevsw, ptc_cdevsw; 327 /* find the major and minor of the pty devices */ 328 if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1) 329 panic("ptmattach: Can't find pty slave in cdevsw"); 330 if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1) 331 panic("ptmattach: Can't find pty master in cdevsw"); 332 #ifdef COMPAT_BSDPTY 333 ptm = &ptm_bsdpty; 334 #endif 335 } 336 337 int 338 /*ARGSUSED*/ 339 ptmopen(dev_t dev, int flag, int mode, struct lwp *l) 340 { 341 int error; 342 int fd; 343 344 switch(minor(dev)) { 345 case 0: /* /dev/ptmx */ 346 if ((error = pty_alloc_master(l, &fd, &dev)) != 0) 347 return error; 348 curlwp->l_dupfd = fd; 349 return ENXIO; 350 case 1: /* /dev/ptm */ 351 return 0; 352 default: 353 return ENODEV; 354 } 355 } 356 357 int 358 /*ARGSUSED*/ 359 ptmclose(dev_t dev, int flag, int mode, struct lwp *l) 360 { 361 return (0); 362 } 363 364 int 365 /*ARGSUSED*/ 366 ptmioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct lwp *l) 367 { 368 int error; 369 dev_t newdev; 370 int cfd, sfd; 371 struct file *fp; 372 struct proc *p = l->l_proc; 373 374 error = 0; 375 switch (cmd) { 376 case TIOCPTMGET: 377 if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0) 378 return error; 379 380 if ((error = pty_grant_slave(l, newdev)) != 0) 381 goto bad; 382 383 if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0) 384 goto bad; 385 386 /* now, put the indices and names into struct ptmget */ 387 return pty_fill_ptmget(newdev, cfd, sfd, data); 388 default: 389 DPRINTF(("ptmioctl EINVAL\n")); 390 return EINVAL; 391 } 392 bad: 393 fp = fd_getfile(p->p_fd, cfd); 394 fdremove(p->p_fd, cfd); 395 ffree(fp); 396 return error; 397 } 398 #endif 399
Indexes created Thu Oct 02 14:10:14 GMT 2025