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tty_ptm.c revision 1.29 
      1 /*	$NetBSD: tty_ptm.c,v 1.29 2014/03/16 05:20:30 dholland 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 1.29 2014/03/16 05:20:30 dholland 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 	.d_open = noopen,
     70 	.d_close = noclose,
     71 	.d_read = noread,
     72 	.d_write = nowrite,
     73 	.d_ioctl = noioctl,
     74 	.d_stop = nostop,
     75 	.d_tty = notty,
     76 	.d_poll = nopoll,
     77 	.d_mmap = nommap,
     78 	.d_kqfilter = nokqfilter,
     79 	.d_flag = D_TTY
     80 };
     81 #else
     82 
     83 static struct ptm_pty *ptm;
     84 int pts_major, ptc_major;
     85 
     86 static dev_t pty_getfree(void);
     87 static int pty_alloc_master(struct lwp *, int *, dev_t *);
     88 static int pty_alloc_slave(struct lwp *, int *, dev_t);
     89 
     90 void ptmattach(int);
     91 
     92 dev_t
     93 pty_makedev(char ms, int minor)
     94 {
     95 	return makedev(ms == 't' ? pts_major : ptc_major, minor);
     96 }
     97 
     98 
     99 static dev_t
    100 pty_getfree(void)
    101 {
    102 	extern kmutex_t pt_softc_mutex;
    103 	int i;
    104 
    105 	mutex_enter(&pt_softc_mutex);
    106 	for (i = 0; i < npty; i++) {
    107 		if (pty_isfree(i, 0))
    108 			break;
    109 	}
    110 	mutex_exit(&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 	int error;
    124 
    125 	if (vp->v_type != VCHR) {
    126 		vput(vp);
    127 		return EINVAL;
    128 	}
    129 
    130 	error = VOP_OPEN(vp, FREAD|FWRITE, lwp0.l_cred);
    131 
    132 	if (error) {
    133 		vput(vp);
    134 		return error;
    135 	}
    136 
    137 	vp->v_writecount++;
    138 
    139 	return 0;
    140 }
    141 
    142 static int
    143 pty_alloc_master(struct lwp *l, int *fd, dev_t *dev)
    144 {
    145 	int error;
    146 	struct file *fp;
    147 	struct vnode *vp;
    148 	int md;
    149 
    150 	if ((error = fd_allocfile(&fp, fd)) != 0) {
    151 		DPRINTF(("fd_allocfile %d\n", error));
    152 		return error;
    153 	}
    154 retry:
    155 	/* Find and open a free master pty. */
    156 	*dev = pty_getfree();
    157 	md = minor(*dev);
    158 	if ((error = pty_check(md)) != 0) {
    159 		DPRINTF(("pty_check %d\n", error));
    160 		goto bad;
    161 	}
    162 	if (ptm == NULL) {
    163 		DPRINTF(("no ptm\n"));
    164 		error = EOPNOTSUPP;
    165 		goto bad;
    166 	}
    167 	if ((error = (*ptm->allocvp)(ptm, l, &vp, *dev, 'p')) != 0) {
    168 		DPRINTF(("pty_allocvp %d\n", error));
    169 		goto bad;
    170 	}
    171 
    172 	if ((error = pty_vn_open(vp, l)) != 0) {
    173 		DPRINTF(("pty_vn_open %d\n", error));
    174 		/*
    175 		 * Check if the master open failed because we lost
    176 		 * the race to grab it.
    177 		 */
    178 		if (error != EIO)
    179 			goto bad;
    180 		error = !pty_isfree(md, 1);
    181 		DPRINTF(("pty_isfree %d\n", error));
    182 		if (error)
    183 			goto retry;
    184 		else
    185 			goto bad;
    186 	}
    187 	fp->f_flag = FREAD|FWRITE;
    188 	fp->f_type = DTYPE_VNODE;
    189 	fp->f_ops = &vnops;
    190 	fp->f_data = vp;
    191 	VOP_UNLOCK(vp);
    192 	fd_affix(curproc, fp, *fd);
    193 	return 0;
    194 bad:
    195 	fd_abort(curproc, fp, *fd);
    196 	return error;
    197 }
    198 
    199 int
    200 pty_grant_slave(struct lwp *l, dev_t dev)
    201 {
    202 	int error;
    203 	struct vnode *vp;
    204 
    205 	/*
    206 	 * Open the slave.
    207 	 * namei -> setattr -> unlock -> revoke -> vrele ->
    208 	 * namei -> open -> unlock
    209 	 * Three stage rocket:
    210 	 * 1. Change the owner and permissions on the slave.
    211 	 * 2. Revoke all the users of the slave.
    212 	 * 3. open the slave.
    213 	 */
    214 	if (ptm == NULL)
    215 		return EOPNOTSUPP;
    216 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    217 		return error;
    218 
    219 	if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
    220 		struct vattr vattr;
    221 		(*ptm->getvattr)(ptm, l, &vattr);
    222 		/* Do the VOP_SETATTR() as root. */
    223 		error = VOP_SETATTR(vp, &vattr, lwp0.l_cred);
    224 		if (error) {
    225 			DPRINTF(("setattr %d\n", error));
    226 			VOP_UNLOCK(vp);
    227 			vrele(vp);
    228 			return error;
    229 		}
    230 	}
    231 	VOP_UNLOCK(vp);
    232 	VOP_REVOKE(vp, REVOKEALL);
    233 
    234 	/*
    235 	 * The vnode is useless after the revoke, we need to get it again.
    236 	 */
    237 	vrele(vp);
    238 	return 0;
    239 }
    240 
    241 static int
    242 pty_alloc_slave(struct lwp *l, int *fd, dev_t dev)
    243 {
    244 	int error;
    245 	struct file *fp;
    246 	struct vnode *vp;
    247 
    248 	/* Grab a filedescriptor for the slave */
    249 	if ((error = fd_allocfile(&fp, fd)) != 0) {
    250 		DPRINTF(("fd_allocfile %d\n", error));
    251 		return error;
    252 	}
    253 
    254 	if (ptm == NULL) {
    255 		error = EOPNOTSUPP;
    256 		goto bad;
    257 	}
    258 
    259 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    260 		goto bad;
    261 	if ((error = pty_vn_open(vp, l)) != 0)
    262 		goto bad;
    263 
    264 	fp->f_flag = FREAD|FWRITE;
    265 	fp->f_type = DTYPE_VNODE;
    266 	fp->f_ops = &vnops;
    267 	fp->f_data = vp;
    268 	VOP_UNLOCK(vp);
    269 	fd_affix(curproc, fp, *fd);
    270 	return 0;
    271 bad:
    272 	fd_abort(curproc, fp, *fd);
    273 	return error;
    274 }
    275 
    276 struct ptm_pty *
    277 pty_sethandler(struct ptm_pty *nptm)
    278 {
    279 	struct ptm_pty *optm = ptm;
    280 	ptm = nptm;
    281 	return optm;
    282 }
    283 
    284 int
    285 pty_fill_ptmget(struct lwp *l, dev_t dev, int cfd, int sfd, void *data)
    286 {
    287 	struct ptmget *ptmg = data;
    288 	int error;
    289 
    290 	if (ptm == NULL)
    291 		return EOPNOTSUPP;
    292 
    293 	ptmg->cfd = cfd == -1 ? minor(dev) : cfd;
    294 	ptmg->sfd = sfd == -1 ? minor(dev) : sfd;
    295 
    296 	error = (*ptm->makename)(ptm, l, ptmg->cn, sizeof(ptmg->cn), dev, 'p');
    297 	if (error)
    298 		return error;
    299 
    300 	return (*ptm->makename)(ptm, l, ptmg->sn, sizeof(ptmg->sn), dev, 't');
    301 }
    302 
    303 void
    304 /*ARGSUSED*/
    305 ptmattach(int n)
    306 {
    307 	extern const struct cdevsw pts_cdevsw, ptc_cdevsw;
    308 	/* find the major and minor of the pty devices */
    309 	if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1)
    310 		panic("ptmattach: Can't find pty slave in cdevsw");
    311 	if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1)
    312 		panic("ptmattach: Can't find pty master in cdevsw");
    313 #ifdef COMPAT_BSDPTY
    314 	ptm = &ptm_bsdpty;
    315 #endif
    316 }
    317 
    318 static int
    319 /*ARGSUSED*/
    320 ptmopen(dev_t dev, int flag, int mode, struct lwp *l)
    321 {
    322 	int error;
    323 	int fd;
    324 	dev_t ttydev;
    325 
    326 	switch(minor(dev)) {
    327 	case 0:		/* /dev/ptmx */
    328 	case 2:		/* /emul/linux/dev/ptmx */
    329 		if ((error = pty_alloc_master(l, &fd, &ttydev)) != 0)
    330 			return error;
    331 		if (minor(dev) == 2) {
    332 			/*
    333 			 * Linux ptyfs grants the pty right here.
    334 			 * Handle this case here, instead of writing
    335 			 * a new linux module.
    336 			 */
    337 			if ((error = pty_grant_slave(l, ttydev)) != 0) {
    338 				file_t *fp = fd_getfile(fd);
    339 				if (fp != NULL) {
    340 					fd_close(fd);
    341 				}
    342 				return error;
    343 			}
    344 		}
    345 		curlwp->l_dupfd = fd;
    346 		return EMOVEFD;
    347 	case 1:		/* /dev/ptm */
    348 		return 0;
    349 	default:
    350 		return ENODEV;
    351 	}
    352 }
    353 
    354 static int
    355 /*ARGSUSED*/
    356 ptmclose(dev_t dev, int flag, int mode, struct lwp *l)
    357 {
    358 
    359 	return (0);
    360 }
    361 
    362 static int
    363 /*ARGSUSED*/
    364 ptmioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    365 {
    366 	int error;
    367 	dev_t newdev;
    368 	int cfd, sfd;
    369 	file_t *fp;
    370 
    371 	error = 0;
    372 	switch (cmd) {
    373 	case TIOCPTMGET:
    374 		if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0)
    375 			return error;
    376 
    377 		if ((error = pty_grant_slave(l, newdev)) != 0)
    378 			goto bad;
    379 
    380 		if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0)
    381 			goto bad;
    382 
    383 		/* now, put the indices and names into struct ptmget */
    384 		return pty_fill_ptmget(l, newdev, cfd, sfd, data);
    385 	default:
    386 #ifdef COMPAT_60
    387 		error = compat_60_ptmioctl(dev, cmd, data, flag, l);
    388 		if (error != EPASSTHROUGH)
    389 			return error;
    390 #endif /* COMPAT_60 */
    391 		DPRINTF(("ptmioctl EINVAL\n"));
    392 		return EINVAL;
    393 	}
    394  bad:
    395 	fp = fd_getfile(cfd);
    396 	if (fp != NULL) {
    397 		fd_close(cfd);
    398 	}
    399 	return error;
    400 }
    401 
    402 const struct cdevsw ptm_cdevsw = {
    403 	.d_open = ptmopen,
    404 	.d_close = ptmclose,
    405 	.d_read = noread,
    406 	.d_write = nowrite,
    407 	.d_ioctl = ptmioctl,
    408 	.d_stop = nullstop,
    409 	.d_tty = notty,
    410 	.d_poll = nopoll,
    411 	.d_mmap = nommap,
    412 	.d_kqfilter = nokqfilter,
    413 	.d_flag = D_TTY
    414 };
    415 #endif
    416