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tty_ptm.c revision 1.25 
      1 /*	$NetBSD: tty_ptm.c,v 1.25 2008/04/28 20:24:05 martin 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 1.25 2008/04/28 20:24:05 martin Exp $");
     31 
     32 #include "opt_ptm.h"
     33 
     34 /* pty multiplexor driver /dev/ptm{,x} */
     35 
     36 #include <sys/param.h>
     37 #include <sys/systm.h>
     38 #include <sys/ioctl.h>
     39 #include <sys/proc.h>
     40 #include <sys/tty.h>
     41 #include <sys/stat.h>
     42 #include <sys/file.h>
     43 #include <sys/uio.h>
     44 #include <sys/kernel.h>
     45 #include <sys/vnode.h>
     46 #include <sys/namei.h>
     47 #include <sys/signalvar.h>
     48 #include <sys/filedesc.h>
     49 #include <sys/conf.h>
     50 #include <sys/poll.h>
     51 #include <sys/malloc.h>
     52 #include <sys/pty.h>
     53 #include <sys/kauth.h>
     54 
     55 #include <miscfs/specfs/specdev.h>
     56 
     57 #ifdef DEBUG_PTM
     58 #define DPRINTF(a)	printf a
     59 #else
     60 #define DPRINTF(a)
     61 #endif
     62 
     63 #ifdef NO_DEV_PTM
     64 const struct cdevsw ptm_cdevsw = {
     65 	noopen, noclose, noread, nowrite, noioctl,
     66 	nostop, notty, nopoll, nommap, nokqfilter, D_TTY
     67 };
     68 #else
     69 
     70 static struct ptm_pty *ptm;
     71 int pts_major, ptc_major;
     72 
     73 static dev_t pty_getfree(void);
     74 static int pty_alloc_master(struct lwp *, int *, dev_t *);
     75 static int pty_alloc_slave(struct lwp *, int *, dev_t);
     76 
     77 void ptmattach(int);
     78 
     79 dev_t
     80 pty_makedev(char ms, int minor)
     81 {
     82 	return makedev(ms == 't' ? pts_major : ptc_major, minor);
     83 }
     84 
     85 
     86 static dev_t
     87 pty_getfree(void)
     88 {
     89 	extern kmutex_t pt_softc_mutex;
     90 	int i;
     91 
     92 	mutex_enter(&pt_softc_mutex);
     93 	for (i = 0; i < npty; i++) {
     94 		if (pty_isfree(i, 0))
     95 			break;
     96 	}
     97 	mutex_exit(&pt_softc_mutex);
     98 	return pty_makedev('t', i);
     99 }
    100 
    101 /*
    102  * Hacked up version of vn_open. We _only_ handle ptys and only open
    103  * them with FREAD|FWRITE and never deal with creat or stuff like that.
    104  *
    105  * We need it because we have to fake up root credentials to open the pty.
    106  */
    107 int
    108 pty_vn_open(struct vnode *vp, struct lwp *l)
    109 {
    110 	int error;
    111 
    112 	if (vp->v_type != VCHR) {
    113 		vput(vp);
    114 		return EINVAL;
    115 	}
    116 
    117 	error = VOP_OPEN(vp, FREAD|FWRITE, lwp0.l_cred);
    118 
    119 	if (error) {
    120 		vput(vp);
    121 		return error;
    122 	}
    123 
    124 	vp->v_writecount++;
    125 
    126 	return 0;
    127 }
    128 
    129 static int
    130 pty_alloc_master(struct lwp *l, int *fd, dev_t *dev)
    131 {
    132 	int error;
    133 	struct file *fp;
    134 	struct vnode *vp;
    135 	int md;
    136 
    137 	if ((error = fd_allocfile(&fp, fd)) != 0) {
    138 		DPRINTF(("fd_allocfile %d\n", error));
    139 		return error;
    140 	}
    141 retry:
    142 	/* Find and open a free master pty. */
    143 	*dev = pty_getfree();
    144 	md = minor(*dev);
    145 	if ((error = pty_check(md)) != 0) {
    146 		DPRINTF(("pty_check %d\n", error));
    147 		goto bad;
    148 	}
    149 	if (ptm == NULL) {
    150 		DPRINTF(("no ptm\n"));
    151 		error = EOPNOTSUPP;
    152 		goto bad;
    153 	}
    154 	if ((error = (*ptm->allocvp)(ptm, l, &vp, *dev, 'p')) != 0) {
    155 		DPRINTF(("pty_allocvp %d\n", error));
    156 		goto bad;
    157 	}
    158 
    159 	if ((error = pty_vn_open(vp, l)) != 0) {
    160 		DPRINTF(("pty_vn_open %d\n", error));
    161 		/*
    162 		 * Check if the master open failed because we lost
    163 		 * the race to grab it.
    164 		 */
    165 		if (error != EIO)
    166 			goto bad;
    167 		error = !pty_isfree(md, 1);
    168 		DPRINTF(("pty_isfree %d\n", error));
    169 		if (error)
    170 			goto retry;
    171 		else
    172 			goto bad;
    173 	}
    174 	fp->f_flag = FREAD|FWRITE;
    175 	fp->f_type = DTYPE_VNODE;
    176 	fp->f_ops = &vnops;
    177 	fp->f_data = vp;
    178 	VOP_UNLOCK(vp, 0);
    179 	fd_affix(curproc, fp, *fd);
    180 	return 0;
    181 bad:
    182 	fd_abort(curproc, fp, *fd);
    183 	return error;
    184 }
    185 
    186 int
    187 pty_grant_slave(struct lwp *l, dev_t dev)
    188 {
    189 	int error;
    190 	struct vnode *vp;
    191 
    192 	/*
    193 	 * Open the slave.
    194 	 * namei -> setattr -> unlock -> revoke -> vrele ->
    195 	 * namei -> open -> unlock
    196 	 * Three stage rocket:
    197 	 * 1. Change the owner and permissions on the slave.
    198 	 * 2. Revoke all the users of the slave.
    199 	 * 3. open the slave.
    200 	 */
    201 	if (ptm == NULL)
    202 		return EOPNOTSUPP;
    203 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    204 		return error;
    205 
    206 	if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
    207 		struct vattr vattr;
    208 		(*ptm->getvattr)(ptm, l, &vattr);
    209 		/* Do the VOP_SETATTR() as root. */
    210 		error = VOP_SETATTR(vp, &vattr, lwp0.l_cred);
    211 		if (error) {
    212 			DPRINTF(("setattr %d\n", error));
    213 			VOP_UNLOCK(vp, 0);
    214 			vrele(vp);
    215 			return error;
    216 		}
    217 	}
    218 	VOP_UNLOCK(vp, 0);
    219 	VOP_REVOKE(vp, REVOKEALL);
    220 
    221 	/*
    222 	 * The vnode is useless after the revoke, we need to get it again.
    223 	 */
    224 	vrele(vp);
    225 	return 0;
    226 }
    227 
    228 static int
    229 pty_alloc_slave(struct lwp *l, int *fd, dev_t dev)
    230 {
    231 	int error;
    232 	struct file *fp;
    233 	struct vnode *vp;
    234 
    235 	/* Grab a filedescriptor for the slave */
    236 	if ((error = fd_allocfile(&fp, fd)) != 0) {
    237 		DPRINTF(("fd_allocfile %d\n", error));
    238 		return error;
    239 	}
    240 
    241 	if (ptm == NULL) {
    242 		error = EOPNOTSUPP;
    243 		goto bad;
    244 	}
    245 
    246 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    247 		goto bad;
    248 	if ((error = pty_vn_open(vp, l)) != 0)
    249 		goto bad;
    250 
    251 	fp->f_flag = FREAD|FWRITE;
    252 	fp->f_type = DTYPE_VNODE;
    253 	fp->f_ops = &vnops;
    254 	fp->f_data = vp;
    255 	VOP_UNLOCK(vp, 0);
    256 	fd_affix(curproc, fp, *fd);
    257 	return 0;
    258 bad:
    259 	fd_abort(curproc, fp, *fd);
    260 	return error;
    261 }
    262 
    263 struct ptm_pty *
    264 pty_sethandler(struct ptm_pty *nptm)
    265 {
    266 	struct ptm_pty *optm = ptm;
    267 	ptm = nptm;
    268 	return optm;
    269 }
    270 
    271 int
    272 pty_fill_ptmget(struct lwp *l, dev_t dev, int cfd, int sfd, void *data)
    273 {
    274 	struct ptmget *ptmg = data;
    275 	int error;
    276 
    277 	if (ptm == NULL)
    278 		return EOPNOTSUPP;
    279 
    280 	ptmg->cfd = cfd == -1 ? minor(dev) : cfd;
    281 	ptmg->sfd = sfd == -1 ? minor(dev) : sfd;
    282 
    283 	error = (*ptm->makename)(ptm, l, ptmg->cn, sizeof(ptmg->cn), dev, 'p');
    284 	if (error)
    285 		return error;
    286 
    287 	return (*ptm->makename)(ptm, l, ptmg->sn, sizeof(ptmg->sn), dev, 't');
    288 }
    289 
    290 void
    291 /*ARGSUSED*/
    292 ptmattach(int n)
    293 {
    294 	extern const struct cdevsw pts_cdevsw, ptc_cdevsw;
    295 	/* find the major and minor of the pty devices */
    296 	if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1)
    297 		panic("ptmattach: Can't find pty slave in cdevsw");
    298 	if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1)
    299 		panic("ptmattach: Can't find pty master in cdevsw");
    300 #ifdef COMPAT_BSDPTY
    301 	ptm = &ptm_bsdpty;
    302 #endif
    303 }
    304 
    305 static int
    306 /*ARGSUSED*/
    307 ptmopen(dev_t dev, int flag, int mode, struct lwp *l)
    308 {
    309 	int error;
    310 	int fd;
    311 	dev_t ttydev;
    312 
    313 	switch(minor(dev)) {
    314 	case 0:		/* /dev/ptmx */
    315 	case 2:		/* /emul/linux/dev/ptmx */
    316 		if ((error = pty_alloc_master(l, &fd, &ttydev)) != 0)
    317 			return error;
    318 		if (minor(dev) == 2) {
    319 			/*
    320 			 * Linux ptyfs grants the pty right here.
    321 			 * Handle this case here, instead of writing
    322 			 * a new linux module.
    323 			 */
    324 			if ((error = pty_grant_slave(l, ttydev)) != 0) {
    325 				file_t *fp = fd_getfile(fd);
    326 				if (fp != NULL) {
    327 					fd_close(fd);
    328 				}
    329 				return error;
    330 			}
    331 		}
    332 		curlwp->l_dupfd = fd;
    333 		return EMOVEFD;
    334 	case 1:		/* /dev/ptm */
    335 		return 0;
    336 	default:
    337 		return ENODEV;
    338 	}
    339 }
    340 
    341 static int
    342 /*ARGSUSED*/
    343 ptmclose(dev_t dev, int flag, int mode, struct lwp *l)
    344 {
    345 
    346 	return (0);
    347 }
    348 
    349 static int
    350 /*ARGSUSED*/
    351 ptmioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    352 {
    353 	int error;
    354 	dev_t newdev;
    355 	int cfd, sfd;
    356 	file_t *fp;
    357 
    358 	error = 0;
    359 	switch (cmd) {
    360 	case TIOCPTMGET:
    361 		if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0)
    362 			return error;
    363 
    364 		if ((error = pty_grant_slave(l, newdev)) != 0)
    365 			goto bad;
    366 
    367 		if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0)
    368 			goto bad;
    369 
    370 		/* now, put the indices and names into struct ptmget */
    371 		return pty_fill_ptmget(l, newdev, cfd, sfd, data);
    372 	default:
    373 		DPRINTF(("ptmioctl EINVAL\n"));
    374 		return EINVAL;
    375 	}
    376  bad:
    377 	fp = fd_getfile(cfd);
    378 	if (fp != NULL) {
    379 		fd_close(cfd);
    380 	}
    381 	return error;
    382 }
    383 
    384 const struct cdevsw ptm_cdevsw = {
    385 	ptmopen, ptmclose, noread, nowrite, ptmioctl,
    386 	nullstop, notty, nopoll, nommap, nokqfilter, D_TTY
    387 };
    388 #endif
    389