FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_ptm.c
1 /* $NetBSD: tty_ptm.c,v 1.4 2004/11/30 04:25:44 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 1.4 2004/11/30 04:25:44 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
62 #ifdef DEBUG_PTM
63 #define DPRINTF(a) printf a
64 #else
65 #define DPRINTF(a)
66 #endif
67
68 #ifdef NO_DEV_PTM
69 const struct cdevsw ptm_cdevsw = {
70 noopen, noclose, noread, nowrite, noioctl,
71 nostop, notty, nopoll, nommap, nokqfilter, D_TTY
72 };
73 #else
74
75 static struct ptm_pty *ptm;
76 int pts_major, ptc_major;
77
78 static dev_t pty_getfree(void);
79 static int pty_alloc_master(struct proc *, int *, dev_t *);
80 static int pty_alloc_slave(struct proc *, int *, dev_t);
81
82 void ptmattach(int);
83
84 dev_type_open(ptmopen);
85 dev_type_close(ptmclose);
86 dev_type_ioctl(ptmioctl);
87
88 const struct cdevsw ptm_cdevsw = {
89 ptmopen, ptmclose, noread, nowrite, ptmioctl,
90 nullstop, notty, nopoll, nommap, nokqfilter, D_TTY
91 };
92
93 dev_t
94 pty_makedev(char ms, int minor)
95 {
96 return makedev(ms == 't' ? pts_major : ptc_major, minor);
97 }
98
99 static dev_t
100 pty_getfree(void)
101 {
102 extern struct simplelock pt_softc_mutex;
103 int i;
104
105 simple_lock(&pt_softc_mutex);
106 for (i = 0; i < npty; i++) {
107 if (pty_isfree(i, 0))
108 break;
109 }
110 simple_unlock(&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 proc *p)
122 {
123 struct ucred *cred;
124 int error;
125
126 if (vp->v_type != VCHR) {
127 vput(vp);
128 return EINVAL;
129 }
130
131 /*
132 * Get us a fresh cred with root privileges.
133 */
134 cred = crget();
135 error = VOP_OPEN(vp, FREAD|FWRITE, cred, p);
136 crfree(cred);
137
138 if (error) {
139 vput(vp);
140 return error;
141 }
142
143 vp->v_writecount++;
144
145 return 0;
146 }
147
148 static int
149 pty_alloc_master(struct proc *p, int *fd, dev_t *dev)
150 {
151 int error;
152 struct file *fp;
153 struct vnode *vp;
154 int md;
155
156 if ((error = falloc(p, &fp, fd)) != 0) {
157 DPRINTF(("falloc %d\n", error));
158 return error;
159 }
160 retry:
161 /* Find and open a free master pty. */
162 *dev = pty_getfree();
163 md = minor(*dev);
164 if ((error = pty_check(md)) != 0) {
165 DPRINTF(("pty_check %d\n", error));
166 goto bad;
167 }
168 if (ptm == NULL) {
169 error = EOPNOTSUPP;
170 goto bad;
171 }
172 if ((error = (*ptm->allocvp)(ptm, p, &vp, *dev, 'p')) != 0)
173 goto bad;
174
175 if ((error = pty_vn_open(vp, p)) != 0) {
176 /*
177 * Check if the master open failed because we lost
178 * the race to grab it.
179 */
180 if (error != EIO)
181 goto bad;
182 error = !pty_isfree(md, 1);
183 if (error)
184 goto retry;
185 else
186 goto bad;
187 }
188 fp->f_flag = FREAD|FWRITE;
189 fp->f_type = DTYPE_VNODE;
190 fp->f_ops = &vnops;
191 fp->f_data = vp;
192 VOP_UNLOCK(vp, 0);
193 FILE_SET_MATURE(fp);
194 FILE_UNUSE(fp, p);
195 return 0;
196 bad:
197 FILE_UNUSE(fp, p);
198 fdremove(p->p_fd, *fd);
199 ffree(fp);
200 return error;
201 }
202
203 int
204 pty_grant_slave(struct proc *p, dev_t dev)
205 {
206 int error;
207 struct vnode *vp;
208
209 /*
210 * Open the slave.
211 * namei -> setattr -> unlock -> revoke -> vrele ->
212 * namei -> open -> unlock
213 * Three stage rocket:
214 * 1. Change the owner and permissions on the slave.
215 * 2. Revoke all the users of the slave.
216 * 3. open the slave.
217 */
218 if (ptm == NULL)
219 return EOPNOTSUPP;
220
221 if ((error = (*ptm->allocvp)(ptm, p, &vp, dev, 't')) != 0)
222 return error;
223
224 if ((vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
225 struct vattr vattr;
226 struct ucred *cred;
227 (*ptm->getvattr)(ptm, p, &vattr);
228 /* Get a fake cred to pretend we're root. */
229 cred = crget();
230 error = VOP_SETATTR(vp, &vattr, cred, p);
231 crfree(cred);
232 if (error) {
233 DPRINTF(("setattr %d\n", error));
234 VOP_UNLOCK(vp, 0);
235 vrele(vp);
236 return error;
237 }
238 }
239 VOP_UNLOCK(vp, 0);
240 if (vp->v_usecount > 1 ||
241 (vp->v_flag & (VALIASED | VLAYER)))
242 VOP_REVOKE(vp, REVOKEALL);
243
244 /*
245 * The vnode is useless after the revoke, we need to get it again.
246 */
247 vrele(vp);
248 return 0;
249 }
250
251 static int
252 pty_alloc_slave(struct proc *p, int *fd, dev_t dev)
253 {
254 int error;
255 struct file *fp;
256 struct vnode *vp;
257
258 /* Grab a filedescriptor for the slave */
259 if ((error = falloc(p, &fp, fd)) != 0) {
260 DPRINTF(("falloc %d\n", error));
261 return error;
262 }
263
264 if (ptm == NULL) {
265 error = EOPNOTSUPP;
266 goto bad;
267 }
268
269 if ((error = (*ptm->allocvp)(ptm, p, &vp, dev, 't')) != 0)
270 goto bad;
271 if ((error = pty_vn_open(vp, p)) != 0)
272 goto bad;
273
274 fp->f_flag = FREAD|FWRITE;
275 fp->f_type = DTYPE_VNODE;
276 fp->f_ops = &vnops;
277 fp->f_data = vp;
278 VOP_UNLOCK(vp, 0);
279 FILE_SET_MATURE(fp);
280 FILE_UNUSE(fp, p);
281 return 0;
282 bad:
283 FILE_UNUSE(fp, p);
284 fdremove(p->p_fd, *fd);
285 ffree(fp);
286 return error;
287 }
288
289 struct ptm_pty *
290 pty_sethandler(struct ptm_pty *nptm)
291 {
292 struct ptm_pty *optm = ptm;
293 ptm = nptm;
294 return optm;
295 }
296
297 int
298 pty_fill_ptmget(dev_t dev, int cfd, int sfd, void *data)
299 {
300 struct ptmget *ptmg = data;
301 int error;
302
303 if (ptm == NULL)
304 return EOPNOTSUPP;
305
306 ptmg->cfd = cfd == -1 ? minor(dev) : cfd;
307 ptmg->sfd = sfd == -1 ? minor(dev) : sfd;
308
309 error = (*ptm->makename)(ptm, ptmg->cn, sizeof(ptmg->cn), dev, 'p');
310 if (error)
311 return error;
312
313 return (*ptm->makename)(ptm, ptmg->sn, sizeof(ptmg->sn), dev, 't');
314 }
315
316 void
317 /*ARGSUSED*/
318 ptmattach(int n)
319 {
320 extern const struct cdevsw pts_cdevsw, ptc_cdevsw;
321 /* find the major and minor of the pty devices */
322 if ((pts_major = cdevsw_lookup_major(&pts_cdevsw)) == -1)
323 panic("ptmattach: Can't find pty slave in cdevsw");
324 if ((ptc_major = cdevsw_lookup_major(&ptc_cdevsw)) == -1)
325 panic("ptmattach: Can't find pty master in cdevsw");
326 #ifdef COMPAT_BSDPTY
327 ptm = &ptm_bsdpty;
328 #endif
329 }
330
331 int
332 /*ARGSUSED*/
333 ptmopen(dev_t dev, int flag, int mode, struct proc *p)
334 {
335 int error;
336 int fd;
337
338 switch(minor(dev)) {
339 case 0: /* /dev/ptmx */
340 if ((error = pty_alloc_master(p, &fd, &dev)) != 0)
341 return error;
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 int
352 /*ARGSUSED*/
353 ptmclose(dev_t dev, int flag, int mode, struct proc *p)
354 {
355 return (0);
356 }
357
358 int
359 /*ARGSUSED*/
360 ptmioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p)
361 {
362 int error;
363 dev_t newdev;
364 int cfd, sfd;
365 struct file *fp;
366
367 error = 0;
368 switch (cmd) {
369 case TIOCPTMGET:
370 if ((error = pty_alloc_master(p, &cfd, &newdev)) != 0)
371 return error;
372
373 if ((error = pty_grant_slave(p, newdev)) != 0)
374 goto bad;
375
376 if ((error = pty_alloc_slave(p, &sfd, newdev)) != 0)
377 goto bad;
378
379 /* now, put the indices and names into struct ptmget */
380 return pty_fill_ptmget(newdev, cfd, sfd, data);
381 default:
382 DPRINTF(("ptmioctl EINVAL\n"));
383 return EINVAL;
384 }
385 bad:
386 fp = fd_getfile(p->p_fd, cfd);
387 fdremove(p->p_fd, cfd);
388 ffree(fp);
389 return error;
390 }
391 #endif
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