tty_ptm.c revision 1.2.2.3
1 /* $NetBSD: tty_ptm.c,v 1.2.2.3 2004/11/29 07:24:51 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 1.2.2.3 2004/11/29 07:24:51 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 (*ptm->getvattr)(ptm, l->l_proc, &vattr); 229 /* Get a fake cred to pretend we're root. */ 230 cred = crget(); 231 error = VOP_SETATTR(vp, &vattr, cred, l); 232 crfree(cred); 233 if (error) { 234 DPRINTF(("setattr %d\n", error)); 235 VOP_UNLOCK(vp, 0); 236 vrele(vp); 237 return error; 238 } 239 } 240 VOP_UNLOCK(vp, 0); 241 if (vp->v_usecount > 1 || 242 (vp->v_flag & (VALIASED | VLAYER))) 243 VOP_REVOKE(vp, REVOKEALL); 244 245 /* 246 * The vnode is useless after the revoke, we need to get it again. 247 */ 248 vrele(vp); 249 return 0; 250 } 251 252 static int 253 pty_alloc_slave(struct lwp *l, int *fd, dev_t dev) 254 { 255 int error; 256 struct file *fp; 257 struct vnode *vp; 258 struct proc *p = l->l_proc; 259 260 /* Grab a filedescriptor for the slave */ 261 if ((error = falloc(p, &fp, fd)) != 0) { 262 DPRINTF(("falloc %d\n", error)); 263 return error; 264 } 265 266 if (ptm == NULL) { 267 error = EOPNOTSUPP; 268 goto bad; 269 } 270 271 if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0) 272 goto bad; 273 if ((error = pty_vn_open(vp, l)) != 0) 274 goto bad; 275 276 fp->f_flag = FREAD|FWRITE; 277 fp->f_type = DTYPE_VNODE; 278 fp->f_ops = &vnops; 279 fp->f_data = vp; 280 VOP_UNLOCK(vp, 0); 281 FILE_SET_MATURE(fp); 282 FILE_UNUSE(fp, l); 283 return 0; 284 bad: 285 FILE_UNUSE(fp, l); 286 fdremove(p->p_fd, *fd); 287 ffree(fp); 288 return error; 289 } 290 291 struct ptm_pty * 292 pty_sethandler(struct ptm_pty *nptm) 293 { 294 struct ptm_pty *optm = ptm; 295 ptm = nptm; 296 return optm; 297 } 298 299 int 300 pty_fill_ptmget(dev_t dev, int cfd, int sfd, void *data) 301 { 302 struct ptmget *ptmg = data; 303 int error; 304 305 if (ptm == NULL) 306 return EOPNOTSUPP; 307 308 ptmg->cfd = cfd == -1 ? minor(dev) : cfd; 309 ptmg->sfd = sfd == -1 ? minor(dev) : sfd; 310 311 error = (*ptm->makename)(ptm, ptmg->cn, sizeof(ptmg->cn), dev, 'p'); 312 if (error) 313 return error; 314 315 return (*ptm->makename)(ptm, ptmg->sn, sizeof(ptmg->sn), dev, 't'); 316 } 317 318 void 319 /*ARGSUSED*/ 320 ptmattach(int n) 321 { 322 extern const struct cdevsw pts_cdevsw, ptc_cdevsw; 323 /* find the major and minor of the pty devices */ 324 if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1) 325 panic("ptmattach: Can't find pty slave in cdevsw"); 326 if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1) 327 panic("ptmattach: Can't find pty master in cdevsw"); 328 #ifdef COMPAT_BSDPTY 329 ptm = &ptm_bsdpty; 330 #endif 331 } 332 333 int 334 /*ARGSUSED*/ 335 ptmopen(dev_t dev, int flag, int mode, struct lwp *l) 336 { 337 int error; 338 int fd; 339 340 switch(minor(dev)) { 341 case 0: /* /dev/ptmx */ 342 if ((error = pty_alloc_master(l, &fd, &dev)) != 0) 343 return error; 344 curlwp->l_dupfd = fd; 345 return ENXIO; 346 case 1: /* /dev/ptm */ 347 return 0; 348 default: 349 return ENODEV; 350 } 351 } 352 353 int 354 /*ARGSUSED*/ 355 ptmclose(dev_t dev, int flag, int mode, struct lwp *l) 356 { 357 return (0); 358 } 359 360 int 361 /*ARGSUSED*/ 362 ptmioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct lwp *l) 363 { 364 int error; 365 dev_t newdev; 366 int cfd, sfd; 367 struct file *fp; 368 struct proc *p = l->l_proc; 369 370 error = 0; 371 switch (cmd) { 372 case TIOCPTMGET: 373 if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0) 374 return error; 375 376 if ((error = pty_grant_slave(l, newdev)) != 0) 377 goto bad; 378 379 if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0) 380 goto bad; 381 382 /* now, put the indices and names into struct ptmget */ 383 return pty_fill_ptmget(newdev, cfd, sfd, data); 384 default: 385 DPRINTF(("ptmioctl EINVAL\n")); 386 return EINVAL; 387 } 388 bad: 389 fp = fd_getfile(p->p_fd, cfd); 390 fdremove(p->p_fd, cfd); 391 ffree(fp); 392 return error; 393 } 394 #endif 395
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