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tty_ptm.c revision 1.24 
      1 /*	$NetBSD: tty_ptm.c,v 1.24 2008/03/21 21:55:00 ad 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 1.24 2008/03/21 21:55:00 ad 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/filedesc.h>
     56 #include <sys/conf.h>
     57 #include <sys/poll.h>
     58 #include <sys/malloc.h>
     59 #include <sys/pty.h>
     60 #include <sys/kauth.h>
     61 
     62 #include <miscfs/specfs/specdev.h>
     63 
     64 #ifdef DEBUG_PTM
     65 #define DPRINTF(a)	printf a
     66 #else
     67 #define DPRINTF(a)
     68 #endif
     69 
     70 #ifdef NO_DEV_PTM
     71 const struct cdevsw ptm_cdevsw = {
     72 	noopen, noclose, noread, nowrite, noioctl,
     73 	nostop, notty, nopoll, nommap, nokqfilter, D_TTY
     74 };
     75 #else
     76 
     77 static struct ptm_pty *ptm;
     78 int pts_major, ptc_major;
     79 
     80 static dev_t pty_getfree(void);
     81 static int pty_alloc_master(struct lwp *, int *, dev_t *);
     82 static int pty_alloc_slave(struct lwp *, int *, dev_t);
     83 
     84 void ptmattach(int);
     85 
     86 dev_t
     87 pty_makedev(char ms, int minor)
     88 {
     89 	return makedev(ms == 't' ? pts_major : ptc_major, minor);
     90 }
     91 
     92 
     93 static dev_t
     94 pty_getfree(void)
     95 {
     96 	extern kmutex_t pt_softc_mutex;
     97 	int i;
     98 
     99 	mutex_enter(&pt_softc_mutex);
    100 	for (i = 0; i < npty; i++) {
    101 		if (pty_isfree(i, 0))
    102 			break;
    103 	}
    104 	mutex_exit(&pt_softc_mutex);
    105 	return pty_makedev('t', i);
    106 }
    107 
    108 /*
    109  * Hacked up version of vn_open. We _only_ handle ptys and only open
    110  * them with FREAD|FWRITE and never deal with creat or stuff like that.
    111  *
    112  * We need it because we have to fake up root credentials to open the pty.
    113  */
    114 int
    115 pty_vn_open(struct vnode *vp, struct lwp *l)
    116 {
    117 	int error;
    118 
    119 	if (vp->v_type != VCHR) {
    120 		vput(vp);
    121 		return EINVAL;
    122 	}
    123 
    124 	error = VOP_OPEN(vp, FREAD|FWRITE, lwp0.l_cred);
    125 
    126 	if (error) {
    127 		vput(vp);
    128 		return error;
    129 	}
    130 
    131 	vp->v_writecount++;
    132 
    133 	return 0;
    134 }
    135 
    136 static int
    137 pty_alloc_master(struct lwp *l, int *fd, dev_t *dev)
    138 {
    139 	int error;
    140 	struct file *fp;
    141 	struct vnode *vp;
    142 	int md;
    143 
    144 	if ((error = fd_allocfile(&fp, fd)) != 0) {
    145 		DPRINTF(("fd_allocfile %d\n", error));
    146 		return error;
    147 	}
    148 retry:
    149 	/* Find and open a free master pty. */
    150 	*dev = pty_getfree();
    151 	md = minor(*dev);
    152 	if ((error = pty_check(md)) != 0) {
    153 		DPRINTF(("pty_check %d\n", error));
    154 		goto bad;
    155 	}
    156 	if (ptm == NULL) {
    157 		DPRINTF(("no ptm\n"));
    158 		error = EOPNOTSUPP;
    159 		goto bad;
    160 	}
    161 	if ((error = (*ptm->allocvp)(ptm, l, &vp, *dev, 'p')) != 0) {
    162 		DPRINTF(("pty_allocvp %d\n", error));
    163 		goto bad;
    164 	}
    165 
    166 	if ((error = pty_vn_open(vp, l)) != 0) {
    167 		DPRINTF(("pty_vn_open %d\n", error));
    168 		/*
    169 		 * Check if the master open failed because we lost
    170 		 * the race to grab it.
    171 		 */
    172 		if (error != EIO)
    173 			goto bad;
    174 		error = !pty_isfree(md, 1);
    175 		DPRINTF(("pty_isfree %d\n", error));
    176 		if (error)
    177 			goto retry;
    178 		else
    179 			goto bad;
    180 	}
    181 	fp->f_flag = FREAD|FWRITE;
    182 	fp->f_type = DTYPE_VNODE;
    183 	fp->f_ops = &vnops;
    184 	fp->f_data = vp;
    185 	VOP_UNLOCK(vp, 0);
    186 	fd_affix(curproc, fp, *fd);
    187 	return 0;
    188 bad:
    189 	fd_abort(curproc, fp, *fd);
    190 	return error;
    191 }
    192 
    193 int
    194 pty_grant_slave(struct lwp *l, dev_t dev)
    195 {
    196 	int error;
    197 	struct vnode *vp;
    198 
    199 	/*
    200 	 * Open the slave.
    201 	 * namei -> setattr -> unlock -> revoke -> vrele ->
    202 	 * namei -> open -> unlock
    203 	 * Three stage rocket:
    204 	 * 1. Change the owner and permissions on the slave.
    205 	 * 2. Revoke all the users of the slave.
    206 	 * 3. open the slave.
    207 	 */
    208 	if (ptm == NULL)
    209 		return EOPNOTSUPP;
    210 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    211 		return error;
    212 
    213 	if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
    214 		struct vattr vattr;
    215 		(*ptm->getvattr)(ptm, l, &vattr);
    216 		/* Do the VOP_SETATTR() as root. */
    217 		error = VOP_SETATTR(vp, &vattr, lwp0.l_cred);
    218 		if (error) {
    219 			DPRINTF(("setattr %d\n", error));
    220 			VOP_UNLOCK(vp, 0);
    221 			vrele(vp);
    222 			return error;
    223 		}
    224 	}
    225 	VOP_UNLOCK(vp, 0);
    226 	VOP_REVOKE(vp, REVOKEALL);
    227 
    228 	/*
    229 	 * The vnode is useless after the revoke, we need to get it again.
    230 	 */
    231 	vrele(vp);
    232 	return 0;
    233 }
    234 
    235 static int
    236 pty_alloc_slave(struct lwp *l, int *fd, dev_t dev)
    237 {
    238 	int error;
    239 	struct file *fp;
    240 	struct vnode *vp;
    241 
    242 	/* Grab a filedescriptor for the slave */
    243 	if ((error = fd_allocfile(&fp, fd)) != 0) {
    244 		DPRINTF(("fd_allocfile %d\n", error));
    245 		return error;
    246 	}
    247 
    248 	if (ptm == NULL) {
    249 		error = EOPNOTSUPP;
    250 		goto bad;
    251 	}
    252 
    253 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    254 		goto bad;
    255 	if ((error = pty_vn_open(vp, l)) != 0)
    256 		goto bad;
    257 
    258 	fp->f_flag = FREAD|FWRITE;
    259 	fp->f_type = DTYPE_VNODE;
    260 	fp->f_ops = &vnops;
    261 	fp->f_data = vp;
    262 	VOP_UNLOCK(vp, 0);
    263 	fd_affix(curproc, fp, *fd);
    264 	return 0;
    265 bad:
    266 	fd_abort(curproc, fp, *fd);
    267 	return error;
    268 }
    269 
    270 struct ptm_pty *
    271 pty_sethandler(struct ptm_pty *nptm)
    272 {
    273 	struct ptm_pty *optm = ptm;
    274 	ptm = nptm;
    275 	return optm;
    276 }
    277 
    278 int
    279 pty_fill_ptmget(struct lwp *l, dev_t dev, int cfd, int sfd, void *data)
    280 {
    281 	struct ptmget *ptmg = data;
    282 	int error;
    283 
    284 	if (ptm == NULL)
    285 		return EOPNOTSUPP;
    286 
    287 	ptmg->cfd = cfd == -1 ? minor(dev) : cfd;
    288 	ptmg->sfd = sfd == -1 ? minor(dev) : sfd;
    289 
    290 	error = (*ptm->makename)(ptm, l, ptmg->cn, sizeof(ptmg->cn), dev, 'p');
    291 	if (error)
    292 		return error;
    293 
    294 	return (*ptm->makename)(ptm, l, ptmg->sn, sizeof(ptmg->sn), dev, 't');
    295 }
    296 
    297 void
    298 /*ARGSUSED*/
    299 ptmattach(int n)
    300 {
    301 	extern const struct cdevsw pts_cdevsw, ptc_cdevsw;
    302 	/* find the major and minor of the pty devices */
    303 	if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1)
    304 		panic("ptmattach: Can't find pty slave in cdevsw");
    305 	if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1)
    306 		panic("ptmattach: Can't find pty master in cdevsw");
    307 #ifdef COMPAT_BSDPTY
    308 	ptm = &ptm_bsdpty;
    309 #endif
    310 }
    311 
    312 static int
    313 /*ARGSUSED*/
    314 ptmopen(dev_t dev, int flag, int mode, struct lwp *l)
    315 {
    316 	int error;
    317 	int fd;
    318 	dev_t ttydev;
    319 
    320 	switch(minor(dev)) {
    321 	case 0:		/* /dev/ptmx */
    322 	case 2:		/* /emul/linux/dev/ptmx */
    323 		if ((error = pty_alloc_master(l, &fd, &ttydev)) != 0)
    324 			return error;
    325 		if (minor(dev) == 2) {
    326 			/*
    327 			 * Linux ptyfs grants the pty right here.
    328 			 * Handle this case here, instead of writing
    329 			 * a new linux module.
    330 			 */
    331 			if ((error = pty_grant_slave(l, ttydev)) != 0) {
    332 				file_t *fp = fd_getfile(fd);
    333 				if (fp != NULL) {
    334 					fd_close(fd);
    335 				}
    336 				return error;
    337 			}
    338 		}
    339 		curlwp->l_dupfd = fd;
    340 		return EMOVEFD;
    341 	case 1:		/* /dev/ptm */
    342 		return 0;
    343 	default:
    344 		return ENODEV;
    345 	}
    346 }
    347 
    348 static int
    349 /*ARGSUSED*/
    350 ptmclose(dev_t dev, int flag, int mode, struct lwp *l)
    351 {
    352 
    353 	return (0);
    354 }
    355 
    356 static int
    357 /*ARGSUSED*/
    358 ptmioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    359 {
    360 	int error;
    361 	dev_t newdev;
    362 	int cfd, sfd;
    363 	file_t *fp;
    364 
    365 	error = 0;
    366 	switch (cmd) {
    367 	case TIOCPTMGET:
    368 		if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0)
    369 			return error;
    370 
    371 		if ((error = pty_grant_slave(l, newdev)) != 0)
    372 			goto bad;
    373 
    374 		if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0)
    375 			goto bad;
    376 
    377 		/* now, put the indices and names into struct ptmget */
    378 		return pty_fill_ptmget(l, newdev, cfd, sfd, data);
    379 	default:
    380 		DPRINTF(("ptmioctl EINVAL\n"));
    381 		return EINVAL;
    382 	}
    383  bad:
    384 	fp = fd_getfile(cfd);
    385 	if (fp != NULL) {
    386 		fd_close(cfd);
    387 	}
    388 	return error;
    389 }
    390 
    391 const struct cdevsw ptm_cdevsw = {
    392 	ptmopen, ptmclose, noread, nowrite, ptmioctl,
    393 	nullstop, notty, nopoll, nommap, nokqfilter, D_TTY
    394 };
    395 #endif
    396