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tty_ptm.c revision 1.16 
      1 /*	$NetBSD: tty_ptm.c,v 1.16 2006/12/27 18:45:30 alc 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 1.16 2006/12/27 18:45:30 alc 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 		DPRINTF(("no ptm\n"));
    157 		error = EOPNOTSUPP;
    158 		goto bad;
    159 	}
    160 	if ((error = (*ptm->allocvp)(ptm, l, &vp, *dev, 'p')) != 0) {
    161 		DPRINTF(("pty_allocvp %d\n", error));
    162 		goto bad;
    163 	}
    164 
    165 	if ((error = pty_vn_open(vp, l)) != 0) {
    166 		DPRINTF(("pty_vn_open %d\n", error));
    167 		/*
    168 		 * Check if the master open failed because we lost
    169 		 * the race to grab it.
    170 		 */
    171 		if (error != EIO)
    172 			goto bad;
    173 		error = !pty_isfree(md, 1);
    174 		DPRINTF(("pty_isfree %d\n", error));
    175 		if (error)
    176 			goto retry;
    177 		else
    178 			goto bad;
    179 	}
    180 	fp->f_flag = FREAD|FWRITE;
    181 	fp->f_type = DTYPE_VNODE;
    182 	fp->f_ops = &vnops;
    183 	fp->f_data = vp;
    184 	VOP_UNLOCK(vp, 0);
    185 	FILE_SET_MATURE(fp);
    186 	FILE_UNUSE(fp, l);
    187 	return 0;
    188 bad:
    189 	FILE_UNUSE(fp, l);
    190 	fdremove(l->l_proc->p_fd, *fd);
    191 	ffree(fp);
    192 	return error;
    193 }
    194 
    195 int
    196 pty_grant_slave(struct lwp *l, dev_t dev)
    197 {
    198 	int error;
    199 	struct vnode *vp;
    200 
    201 	/*
    202 	 * Open the slave.
    203 	 * namei -> setattr -> unlock -> revoke -> vrele ->
    204 	 * namei -> open -> unlock
    205 	 * Three stage rocket:
    206 	 * 1. Change the owner and permissions on the slave.
    207 	 * 2. Revoke all the users of the slave.
    208 	 * 3. open the slave.
    209 	 */
    210 	if (ptm == NULL)
    211 		return EOPNOTSUPP;
    212 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    213 		return error;
    214 
    215 	if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
    216 		struct vattr vattr;
    217 		(*ptm->getvattr)(ptm, l, &vattr);
    218 		/* Do the VOP_SETATTR() as root. */
    219 		error = VOP_SETATTR(vp, &vattr, lwp0.l_cred, l);
    220 		if (error) {
    221 			DPRINTF(("setattr %d\n", error));
    222 			VOP_UNLOCK(vp, 0);
    223 			vrele(vp);
    224 			return error;
    225 		}
    226 	}
    227 	VOP_UNLOCK(vp, 0);
    228 	if (vp->v_usecount > 1 ||
    229 	    (vp->v_flag & (VALIASED | VLAYER)))
    230 		VOP_REVOKE(vp, REVOKEALL);
    231 
    232 	/*
    233 	 * The vnode is useless after the revoke, we need to get it again.
    234 	 */
    235 	vrele(vp);
    236 	return 0;
    237 }
    238 
    239 static int
    240 pty_alloc_slave(struct lwp *l, int *fd, dev_t dev)
    241 {
    242 	int error;
    243 	struct file *fp;
    244 	struct vnode *vp;
    245 
    246 	/* Grab a filedescriptor for the slave */
    247 	if ((error = falloc(l, &fp, fd)) != 0) {
    248 		DPRINTF(("falloc %d\n", error));
    249 		return error;
    250 	}
    251 
    252 	if (ptm == NULL) {
    253 		error = EOPNOTSUPP;
    254 		goto bad;
    255 	}
    256 
    257 	if ((error = (*ptm->allocvp)(ptm, l, &vp, dev, 't')) != 0)
    258 		goto bad;
    259 	if ((error = pty_vn_open(vp, l)) != 0)
    260 		goto bad;
    261 
    262 	fp->f_flag = FREAD|FWRITE;
    263 	fp->f_type = DTYPE_VNODE;
    264 	fp->f_ops = &vnops;
    265 	fp->f_data = vp;
    266 	VOP_UNLOCK(vp, 0);
    267 	FILE_SET_MATURE(fp);
    268 	FILE_UNUSE(fp, l);
    269 	return 0;
    270 bad:
    271 	FILE_UNUSE(fp, l);
    272 	fdremove(l->l_proc->p_fd, *fd);
    273 	ffree(fp);
    274 	return error;
    275 }
    276 
    277 struct ptm_pty *
    278 pty_sethandler(struct ptm_pty *nptm)
    279 {
    280 	struct ptm_pty *optm = ptm;
    281 	ptm = nptm;
    282 	return optm;
    283 }
    284 
    285 int
    286 pty_fill_ptmget(struct lwp *l, dev_t dev, int cfd, int sfd, void *data)
    287 {
    288 	struct ptmget *ptmg = data;
    289 	int error;
    290 
    291 	if (ptm == NULL)
    292 		return EOPNOTSUPP;
    293 
    294 	ptmg->cfd = cfd == -1 ? minor(dev) : cfd;
    295 	ptmg->sfd = sfd == -1 ? minor(dev) : sfd;
    296 
    297 	error = (*ptm->makename)(ptm, l, ptmg->cn, sizeof(ptmg->cn), dev, 'p');
    298 	if (error)
    299 		return error;
    300 
    301 	return (*ptm->makename)(ptm, l, ptmg->sn, sizeof(ptmg->sn), dev, 't');
    302 }
    303 
    304 void
    305 /*ARGSUSED*/
    306 ptmattach(int n)
    307 {
    308 	extern const struct cdevsw pts_cdevsw, ptc_cdevsw;
    309 	/* find the major and minor of the pty devices */
    310 	if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1)
    311 		panic("ptmattach: Can't find pty slave in cdevsw");
    312 	if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1)
    313 		panic("ptmattach: Can't find pty master in cdevsw");
    314 #ifdef COMPAT_BSDPTY
    315 	ptm = &ptm_bsdpty;
    316 #endif
    317 }
    318 
    319 static int
    320 /*ARGSUSED*/
    321 ptmopen(dev_t dev, int flag, int mode, struct lwp *l)
    322 {
    323 	int error;
    324 	int fd;
    325 	dev_t ttydev;
    326 
    327 	switch(minor(dev)) {
    328 	case 0:		/* /dev/ptmx */
    329 	case 2:		/* /emul/linux/dev/ptmx */
    330 		if ((error = pty_alloc_master(l, &fd, &ttydev)) != 0)
    331 			return error;
    332 		if (minor(dev) == 2) {
    333 			/*
    334 			 * Linux ptyfs grants the pty right here.
    335 			 * Handle this case here, instead of writing
    336 			 * a new linux module.
    337 			 */
    338 			if ((error = pty_grant_slave(l, ttydev)) != 0) {
    339 				struct file *fp =
    340 				    fd_getfile(l->l_proc->p_fd, fd);
    341 				if (fp != NULL) {
    342 					FILE_UNUSE(fp, l);
    343 					fdremove(l->l_proc->p_fd, fd);
    344 					ffree(fp);
    345 				}
    346 				return error;
    347 			}
    348 		}
    349 		curlwp->l_dupfd = fd;
    350 		return EMOVEFD;
    351 	case 1:		/* /dev/ptm */
    352 		return 0;
    353 	default:
    354 		return ENODEV;
    355 	}
    356 }
    357 
    358 static int
    359 /*ARGSUSED*/
    360 ptmclose(dev_t dev, int flag, int mode, struct lwp *l)
    361 {
    362 
    363 	return (0);
    364 }
    365 
    366 static int
    367 /*ARGSUSED*/
    368 ptmioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct lwp *l)
    369 {
    370 	int error;
    371 	dev_t newdev;
    372 	int cfd, sfd;
    373 	struct file *fp;
    374 	struct proc *p = l->l_proc;
    375 
    376 	error = 0;
    377 	switch (cmd) {
    378 	case TIOCPTMGET:
    379 		if ((error = pty_alloc_master(l, &cfd, &newdev)) != 0)
    380 			return error;
    381 
    382 		if ((error = pty_grant_slave(l, newdev)) != 0)
    383 			goto bad;
    384 
    385 		if ((error = pty_alloc_slave(l, &sfd, newdev)) != 0)
    386 			goto bad;
    387 
    388 		/* now, put the indices and names into struct ptmget */
    389 		return pty_fill_ptmget(l, newdev, cfd, sfd, data);
    390 	default:
    391 		DPRINTF(("ptmioctl EINVAL\n"));
    392 		return EINVAL;
    393 	}
    394 bad:
    395 	fp = fd_getfile(p->p_fd, cfd);
    396 	if (fp != NULL) {
    397 		FILE_UNUSE(fp, l);
    398 		fdremove(p->p_fd, cfd);
    399 		ffree(fp);
    400 	}
    401 	return error;
    402 }
    403 
    404 const struct cdevsw ptm_cdevsw = {
    405 	ptmopen, ptmclose, noread, nowrite, ptmioctl,
    406 	nullstop, notty, nopoll, nommap, nokqfilter, D_TTY
    407 };
    408 #endif
    409