Home | History | Annotate | Line # | Download | only in kern
tty_ptm.c revision 1.12 
      1 /*	$NetBSD: tty_ptm.c,v 1.12 2006/09/22 15:15:56 christos 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 1.12 2006/09/22 15:15:56 christos 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 #include <sys/kauth.h>
     62 
     63 #ifdef DEBUG_PTM
     64 #define DPRINTF(a)	printf a
     65 #else
     66 #define DPRINTF(a)
     67 #endif
     68 
     69 #ifdef NO_DEV_PTM
     70 const struct cdevsw ptm_cdevsw = {
     71 	noopen, noclose, noread, nowrite, noioctl,
     72 	nostop, notty, nopoll, nommap, nokqfilter, D_TTY
     73 };
     74 #else
     75 
     76 static struct ptm_pty *ptm;
     77 int pts_major, ptc_major;
     78 
     79 static dev_t pty_getfree(void);
     80 static int pty_alloc_master(struct lwp *, int *, dev_t *);
     81 static int pty_alloc_slave(struct lwp *, int *, dev_t);
     82 
     83 void ptmattach(int);
     84 
     85 dev_t
     86 pty_makedev(char ms, int minor)
     87 {
     88 	return makedev(ms == 't' ? pts_major : ptc_major, minor);
     89 }
     90 
     91 
     92 static dev_t
     93 pty_getfree(void)
     94 {
     95 	extern struct simplelock pt_softc_mutex;
     96 	int i;
     97 
     98 	simple_lock(&pt_softc_mutex);
     99 	for (i = 0; i < npty; i++) {
    100 		if (pty_isfree(i, 0))
    101 			break;
    102 	}
    103 	simple_unlock(&pt_softc_mutex);
    104 	return pty_makedev('t', i);
    105 }
    106 
    107 /*
    108  * Hacked up version of vn_open. We _only_ handle ptys and only open
    109  * them with FREAD|FWRITE and never deal with creat or stuff like that.
    110  *
    111  * We need it because we have to fake up root credentials to open the pty.
    112  */
    113 int
    114 pty_vn_open(struct vnode *vp, struct lwp *l)
    115 {
    116 	int error;
    117 
    118 	if (vp->v_type != VCHR) {
    119 		vput(vp);
    120 		return EINVAL;
    121 	}
    122 
    123 	error = VOP_OPEN(vp, FREAD|FWRITE, lwp0.l_cred, l);
    124 
    125 	if (error) {
    126 		vput(vp);
    127 		return error;
    128 	}
    129 
    130 	vp->v_writecount++;
    131 
    132 	return 0;
    133 }
    134 
    135 static int
    136 pty_alloc_master(struct lwp *l, int *fd, dev_t *dev)
    137 {
    138 	int error;
    139 	struct file *fp;
    140 	struct vnode *vp;
    141 	int md;
    142 
    143 	if ((error = falloc(l, &fp, fd)) != 0) {
    144 		DPRINTF(("falloc %d\n", error));
    145 		return error;
    146 	}
    147 retry:
    148 	/* Find and open a free master pty. */
    149 	*dev = pty_getfree();
    150 	md = minor(*dev);
    151 	if ((error = pty_check(md)) != 0) {
    152 		DPRINTF(("pty_check %d\n", error));
    153 		goto bad;
    154 	}
    155 	if (ptm == NULL) {
    156 		error = EOPNOTSUPP;
    157 		goto bad;
    158 	}
    159 	if ((error = (*ptm->allocvp)(ptm, l, &vp, *dev, 'p')) != 0)
    160 		goto bad;
    161 
    162 	if ((error = pty_vn_open(vp, l)) != 0) {
    163 		/*
    164 		 * Check if the master open failed because we lost
    165 		 * the race to grab it.
    166 		 */
    167 		if (error != EIO)
    168 			goto bad;
    169 		error = !pty_isfree(md, 1);
    170 		if (error)
    171 			goto retry;
    172 		else
    173 			goto bad;
    174 	}
    175 	fp->f_flag = FREAD|FWRITE;
    176 	fp->f_type = DTYPE_VNODE;
    177 	fp->f_ops = &vnops;
    178 	fp->f_data = vp;
    179 	VOP_UNLOCK(vp, 0);
    180 	FILE_SET_MATURE(fp);
    181 	FILE_UNUSE(fp, l);
    182 	return 0;
    183 bad:
    184 	FILE_UNUSE(fp, l);
    185 	fdremove(l->l_proc->p_fd, *fd);
    186 	ffree(fp);
    187 	return error;
    188 }
    189 
    190 int
    191 pty_grant_slave(struct lwp *l, dev_t dev)
    192 {
    193 	int error;
    194 	struct vnode *vp;
    195 
    196 	/*
    197 	 * Open the slave.
    198 	 * namei -> setattr -> unlock -> revoke -> vrele ->
    199 	 * namei -> open -> unlock
    200 	 * Three stage rocket:
    201 	 * 1. Change the owner and permissions on the slave.
    202 	 * 2. Revoke all the users of the slave.
    203 	 * 3. open the slave.
    204 	 */
    205 	if (ptm == NULL)
    206 		return EOPNOTSUPP;
    207 
    208 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    209 		return error;
    210 
    211 	if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
    212 		struct vattr vattr;
    213 		(*ptm->getvattr)(ptm, l, &vattr);
    214 		/* Do the VOP_SETATTR() as root. */
    215 		error = VOP_SETATTR(vp, &vattr, lwp0.l_cred, l);
    216 		if (error) {
    217 			DPRINTF(("setattr %d\n", error));
    218 			VOP_UNLOCK(vp, 0);
    219 			vrele(vp);
    220 			return error;
    221 		}
    222 	}
    223 	VOP_UNLOCK(vp, 0);
    224 	if (vp->v_usecount > 1 ||
    225 	    (vp->v_flag & (VALIASED | VLAYER)))
    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 = falloc(l, &fp, fd)) != 0) {
    244 		DPRINTF(("falloc %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 	FILE_SET_MATURE(fp);
    264 	FILE_UNUSE(fp, l);
    265 	return 0;
    266 bad:
    267 	FILE_UNUSE(fp, l);
    268 	fdremove(l->l_proc->p_fd, *fd);
    269 	ffree(fp);
    270 	return error;
    271 }
    272 
    273 struct ptm_pty *
    274 pty_sethandler(struct ptm_pty *nptm)
    275 {
    276 	struct ptm_pty *optm = ptm;
    277 	ptm = nptm;
    278 	return optm;
    279 }
    280 
    281 int
    282 pty_fill_ptmget(struct lwp *l, dev_t dev, int cfd, int sfd, void *data)
    283 {
    284 	struct ptmget *ptmg = data;
    285 	int error;
    286 
    287 	if (ptm == NULL)
    288 		return EOPNOTSUPP;
    289 
    290 	ptmg->cfd = cfd == -1 ? minor(dev) : cfd;
    291 	ptmg->sfd = sfd == -1 ? minor(dev) : sfd;
    292 
    293 	error = (*ptm->makename)(ptm, l, ptmg->cn, sizeof(ptmg->cn), dev, 'p');
    294 	if (error)
    295 		return error;
    296 
    297 	return (*ptm->makename)(ptm, l, ptmg->sn, sizeof(ptmg->sn), dev, 't');
    298 }
    299 
    300 void
    301 /*ARGSUSED*/
    302 ptmattach(int n)
    303 {
    304 	extern const struct cdevsw pts_cdevsw, ptc_cdevsw;
    305 	/* find the major and minor of the pty devices */
    306 	if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1)
    307 		panic("ptmattach: Can't find pty slave in cdevsw");
    308 	if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1)
    309 		panic("ptmattach: Can't find pty master in cdevsw");
    310 #ifdef COMPAT_BSDPTY
    311 	ptm = &ptm_bsdpty;
    312 #endif
    313 }
    314 
    315 static int
    316 /*ARGSUSED*/
    317 ptmopen(dev_t dev, int flag, int mode, struct lwp *l)
    318 {
    319 	int error;
    320 	int fd;
    321 
    322 	switch(minor(dev)) {
    323 	case 0:		/* /dev/ptmx */
    324 	case 2:		/* /emul/linux/dev/ptmx */
    325 		if ((error = pty_alloc_master(l, &fd, &dev)) != 0)
    326 			return error;
    327 		if (minor(dev) == 2) {
    328 			/*
    329 			 * Linux ptyfs grants the pty right here.
    330 			 * Handle this case here, instead of writing
    331 			 * a new linux module.
    332 			 */
    333 			if ((error = pty_grant_slave(l, dev)) != 0) {
    334 				struct file *fp =
    335 				    fd_getfile(l->l_proc->p_fd, fd);
    336 				FILE_UNUSE(fp, l);
    337 				fdremove(l->l_proc->p_fd, fd);
    338 				ffree(fp);
    339 				return error;
    340 			}
    341 		}
    342 		curlwp->l_dupfd = fd;
    343 		return EMOVEFD;
    344 	case 1:		/* /dev/ptm */
    345 		return 0;
    346 	default:
    347 		return ENODEV;
    348 	}
    349 }
    350 
    351 static int
    352 /*ARGSUSED*/
    353 ptmclose(dev_t dev, int flag, int mode, struct lwp *l)
    354 {
    355 	return (0);
    356 }
    357 
    358 static int
    359 /*ARGSUSED*/
    360 ptmioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct lwp *l)
    361 {
    362 	int error;
    363 	dev_t newdev;
    364 	int cfd, sfd;
    365 	struct file *fp;
    366 	struct proc *p = l->l_proc;
    367 
    368 	error = 0;
    369 	switch (cmd) {
    370 	case TIOCPTMGET:
    371 		if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0)
    372 			return error;
    373 
    374 		if ((error = pty_grant_slave(l, newdev)) != 0)
    375 			goto bad;
    376 
    377 		if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0)
    378 			goto bad;
    379 
    380 		/* now, put the indices and names into struct ptmget */
    381 		return pty_fill_ptmget(l, newdev, cfd, sfd, data);
    382 	default:
    383 		DPRINTF(("ptmioctl EINVAL\n"));
    384 		return EINVAL;
    385 	}
    386 bad:
    387 	fp = fd_getfile(p->p_fd, cfd);
    388 	FILE_UNUSE(fp, l);
    389 	fdremove(p->p_fd, cfd);
    390 	ffree(fp);
    391 	return error;
    392 }
    393 
    394 const struct cdevsw ptm_cdevsw = {
    395 	ptmopen, ptmclose, noread, nowrite, ptmioctl,
    396 	nullstop, notty, nopoll, nommap, nokqfilter, D_TTY
    397 };
    398 #endif
    399