xref: /netbsd-src/sys/fs/ptyfs/ptyfs_vfsops.c (revision bdc22b2e01993381dcefeff2bc9b56ca75a4235c) 
1 /*	$NetBSD: ptyfs_vfsops.c,v 1.56 2017/02/17 08:31:24 hannken Exp $	*/
2 
3 /*
4  * Copyright (c) 1992, 1993, 1995
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software donated to Berkeley by
8  * Jan-Simon Pendry.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  */
35 
36 /*
37  * Pseudo-tty Filesystem
38  */
39 
40 #include <sys/cdefs.h>
41 __KERNEL_RCSID(0, "$NetBSD: ptyfs_vfsops.c,v 1.56 2017/02/17 08:31:24 hannken Exp $");
42 
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/sysctl.h>
46 #include <sys/conf.h>
47 #include <sys/proc.h>
48 #include <sys/vnode.h>
49 #include <sys/mount.h>
50 #include <sys/namei.h>
51 #include <sys/stat.h>
52 #include <sys/dirent.h>
53 #include <sys/malloc.h>
54 #include <sys/syslog.h>
55 #include <sys/select.h>
56 #include <sys/filedesc.h>
57 #include <sys/tty.h>
58 #include <sys/pty.h>
59 #include <sys/kauth.h>
60 #include <sys/module.h>
61 
62 #include <fs/ptyfs/ptyfs.h>
63 #include <miscfs/genfs/genfs.h>
64 #include <miscfs/specfs/specdev.h>
65 
66 MODULE(MODULE_CLASS_VFS, ptyfs, NULL);
67 
68 MALLOC_JUSTDEFINE(M_PTYFSMNT, "ptyfs mount", "ptyfs mount structures");
69 MALLOC_JUSTDEFINE(M_PTYFSTMP, "ptyfs temp", "ptyfs temporary structures");
70 
71 VFS_PROTOS(ptyfs);
72 
73 static struct sysctllog *ptyfs_sysctl_log;
74 
75 static int ptyfs__allocvp(struct mount *, struct lwp *, struct vnode **,
76     dev_t, char);
77 static int ptyfs__makename(struct mount *, struct lwp *, char *, size_t,
78     dev_t, char);
79 static void ptyfs__getvattr(struct mount *, struct lwp *, struct vattr *);
80 static int ptyfs__getmp(struct lwp *, struct mount **);
81 
82 /*
83  * ptm glue: When we mount, we make ptm point to us.
84  */
85 struct ptm_pty *ptyfs_save_ptm;
86 static int ptyfs_count;
87 
88 static TAILQ_HEAD(, ptyfsmount) ptyfs_head;
89 
90 struct ptm_pty ptm_ptyfspty = {
91 	ptyfs__allocvp,
92 	ptyfs__makename,
93 	ptyfs__getvattr,
94 	ptyfs__getmp,
95 };
96 
97 static int
98 ptyfs__getmp(struct lwp *l, struct mount **mpp)
99 {
100  	struct cwdinfo *cwdi = l->l_proc->p_cwdi;
101  	struct mount *mp;
102 	struct ptyfsmount *pmnt;
103 
104 	TAILQ_FOREACH(pmnt, &ptyfs_head, pmnt_le) {
105 		mp = pmnt->pmnt_mp;
106 		if (cwdi->cwdi_rdir == NULL)
107 			goto ok;
108 
109 		if (vn_isunder(mp->mnt_vnodecovered, cwdi->cwdi_rdir, l))
110 			goto ok;
111 	}
112  	*mpp = NULL;
113  	return EOPNOTSUPP;
114 ok:
115 	*mpp = mp;
116 	return 0;
117 }
118 
119 static const char *
120 ptyfs__getpath(struct lwp *l, const struct mount *mp)
121 {
122 #define MAXBUF (sizeof(mp->mnt_stat.f_mntonname) + 32)
123 	struct cwdinfo *cwdi = l->l_proc->p_cwdi;
124 	char *buf;
125 	const char *rv;
126 	size_t len;
127 	char *bp;
128 	int error;
129 
130 	rv = mp->mnt_stat.f_mntonname;
131 	if (cwdi->cwdi_rdir == NULL)
132 		return rv;
133 
134 	buf = malloc(MAXBUF, M_TEMP, M_WAITOK);
135 	bp = buf + MAXBUF;
136 	*--bp = '\0';
137 	error = getcwd_common(mp->mnt_vnodecovered, cwdi->cwdi_rdir, &bp,
138 	    buf, MAXBUF / 2, 0, l);
139 	if (error) {	/* Mount point is out of rdir */
140 		rv = NULL;
141 		goto out;
142 	}
143 
144 	len = strlen(bp);
145 	if (len < sizeof(mp->mnt_stat.f_mntonname))	/* XXX */
146 		rv += strlen(rv) - len;
147 out:
148 	free(buf, M_TEMP);
149 	return rv;
150 }
151 
152 static int
153 ptyfs__makename(struct mount *mp, struct lwp *l, char *tbuf, size_t bufsiz,
154     dev_t dev, char ms)
155 {
156 	size_t len;
157 	const char *np;
158 	int pty = minor(dev);
159 
160 	switch (ms) {
161 	case 'p':
162 		/* We don't provide access to the master, should we? */
163 		len = snprintf(tbuf, bufsiz, "/dev/null");
164 		break;
165 	case 't':
166 		/*
167 		 * We support traditional ptys, so we can get here,
168 		 * if pty had been opened before PTYFS was mounted,
169 		 * or was opened through /dev/ptyXX devices.
170 		 * Return it only outside chroot for more security .
171 		 */
172 		if (l->l_proc->p_cwdi->cwdi_rdir == NULL
173 		    && ptyfs_save_ptm != NULL
174 		    && ptyfs_next_active(mp, pty) != pty)
175 			return (*ptyfs_save_ptm->makename)(mp, l,
176 			    tbuf, bufsiz, dev, ms);
177 
178 		np = ptyfs__getpath(l, mp);
179 		if (np == NULL)
180 			return EOPNOTSUPP;
181 		len = snprintf(tbuf, bufsiz, "%s/%llu", np,
182 			(unsigned long long)minor(dev));
183 		break;
184 	default:
185 		return EINVAL;
186 	}
187 
188 	return len >= bufsiz ? ENOSPC : 0;
189 }
190 
191 
192 static int
193 /*ARGSUSED*/
194 ptyfs__allocvp(struct mount *mp, struct lwp *l, struct vnode **vpp,
195     dev_t dev, char ms)
196 {
197 	int error;
198 	ptyfstype type;
199 
200 	switch (ms) {
201 	case 'p':
202 		type = PTYFSptc;
203 		break;
204 	case 't':
205 		type = PTYFSpts;
206 		break;
207 	default:
208 		return EINVAL;
209 	}
210 
211 	error = ptyfs_allocvp(mp, vpp, type, minor(dev));
212 	if (error)
213 		return error;
214 	error = vn_lock(*vpp, LK_EXCLUSIVE);
215 	if (error) {
216 		vrele(*vpp);
217 		*vpp = NULL;
218 		return error;
219 	}
220 	if (type == PTYFSptc)
221 		ptyfs_set_active(mp, minor(dev));
222 	return 0;
223 }
224 
225 
226 static void
227 ptyfs__getvattr(struct mount *mp, struct lwp *l, struct vattr *vattr)
228 {
229 	struct ptyfsmount *pmnt = VFSTOPTY(mp);
230 	vattr_null(vattr);
231 	/* get real uid */
232 	vattr->va_uid = kauth_cred_getuid(l->l_cred);
233 	vattr->va_gid = pmnt->pmnt_gid;
234 	vattr->va_mode = pmnt->pmnt_mode;
235 }
236 
237 
238 void
239 ptyfs_init(void)
240 {
241 
242 	TAILQ_INIT(&ptyfs_head);
243 	malloc_type_attach(M_PTYFSMNT);
244 	malloc_type_attach(M_PTYFSTMP);
245 	ptyfs_hashinit();
246 }
247 
248 void
249 ptyfs_reinit(void)
250 {
251 
252 }
253 
254 void
255 ptyfs_done(void)
256 {
257 
258 	ptyfs_hashdone();
259 	malloc_type_detach(M_PTYFSTMP);
260 	malloc_type_detach(M_PTYFSMNT);
261 }
262 
263 #define OSIZE sizeof(struct { int f; gid_t g; mode_t m; })
264 /*
265  * Mount the Pseudo tty params filesystem
266  */
267 int
268 ptyfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
269 {
270 	struct lwp *l = curlwp;
271 	int error = 0;
272 	struct ptyfsmount *pmnt;
273 	struct ptyfs_args *args = data;
274 
275 	if (args == NULL)
276 		return EINVAL;
277 	if (*data_len != sizeof *args) {
278 		if (*data_len != OSIZE || args->version >= PTYFS_ARGSVERSION)
279 			return EINVAL;
280 	}
281 
282 	if (UIO_MX & (UIO_MX - 1)) {
283 		log(LOG_ERR, "ptyfs: invalid directory entry size");
284 		return EINVAL;
285 	}
286 
287 	if (mp->mnt_flag & MNT_GETARGS) {
288 		pmnt = VFSTOPTY(mp);
289 		if (pmnt == NULL)
290 			return EIO;
291 		args->mode = pmnt->pmnt_mode;
292 		args->gid = pmnt->pmnt_gid;
293 		if (args->version >= PTYFS_ARGSVERSION) {
294 			args->flags = pmnt->pmnt_flags;
295 			*data_len = sizeof *args;
296 		} else {
297 			*data_len = OSIZE;
298 		}
299 		return 0;
300 	}
301 
302 #if 0
303 	/* Don't allow more than one mount */
304 	if (ptyfs_count)
305 		return EBUSY;
306 #endif
307 
308 	if (mp->mnt_flag & MNT_UPDATE)
309 		return EOPNOTSUPP;
310 
311 	if (args->version > PTYFS_ARGSVERSION)
312 		return EINVAL;
313 
314 	pmnt = malloc(sizeof(struct ptyfsmount), M_PTYFSMNT, M_WAITOK);
315 
316 	mp->mnt_data = pmnt;
317 	mutex_init(&pmnt->pmnt_lock, MUTEX_DEFAULT, IPL_NONE);
318 	pmnt->pmnt_gid = args->gid;
319 	pmnt->pmnt_mode = args->mode;
320 	if (args->version >= PTYFS_ARGSVERSION)
321 		pmnt->pmnt_flags = args->flags;
322 	else
323 		pmnt->pmnt_flags = 0;
324 	pmnt->pmnt_bitmap_size = 0;
325 	pmnt->pmnt_bitmap = NULL;
326 	mp->mnt_flag |= MNT_LOCAL;
327 	vfs_getnewfsid(mp);
328 
329 	if ((error = set_statvfs_info(path, UIO_USERSPACE, "ptyfs",
330 	    UIO_SYSSPACE, mp->mnt_op->vfs_name, mp, l)) != 0) {
331 		free(pmnt, M_PTYFSMNT);
332 		return error;
333 	}
334 
335 	pmnt->pmnt_mp = mp;
336 	TAILQ_INSERT_TAIL(&ptyfs_head, pmnt, pmnt_le);
337 	if (ptyfs_count++ == 0) {
338 		/* Point pty access to us */
339 		ptyfs_save_ptm = pty_sethandler(&ptm_ptyfspty);
340 	}
341 	return 0;
342 }
343 
344 /*ARGSUSED*/
345 int
346 ptyfs_start(struct mount *mp, int flags)
347 {
348 	return 0;
349 }
350 
351 /*ARGSUSED*/
352 int
353 ptyfs_unmount(struct mount *mp, int mntflags)
354 {
355 	int error;
356 	int flags = 0;
357 	struct ptyfsmount *pmnt;
358 
359 	if (mntflags & MNT_FORCE)
360 		flags |= FORCECLOSE;
361 
362 	if ((error = vflush(mp, 0, flags)) != 0)
363 		return error;
364 
365 	ptyfs_count--;
366 	if (ptyfs_count == 0) {
367 		/* Restore where pty access was pointing */
368 		(void)pty_sethandler(ptyfs_save_ptm);
369 		ptyfs_save_ptm = NULL;
370 	}
371 	TAILQ_FOREACH(pmnt, &ptyfs_head, pmnt_le) {
372 		if (pmnt->pmnt_mp == mp) {
373 			TAILQ_REMOVE(&ptyfs_head, pmnt, pmnt_le);
374 			break;
375 		}
376  	}
377 
378 	/*
379 	 * Finally, throw away the ptyfsmount structure
380 	 */
381 	if (pmnt->pmnt_bitmap_size > 0)
382 		kmem_free(pmnt->pmnt_bitmap, pmnt->pmnt_bitmap_size);
383 	mutex_destroy(&pmnt->pmnt_lock);
384 	free(mp->mnt_data, M_PTYFSMNT);
385 	mp->mnt_data = NULL;
386 
387 	return 0;
388 }
389 
390 int
391 ptyfs_root(struct mount *mp, struct vnode **vpp)
392 {
393 	int error;
394 
395 	/* setup "." */
396 	error = ptyfs_allocvp(mp, vpp, PTYFSroot, 0);
397 	if (error)
398 		return error;
399 	error = vn_lock(*vpp, LK_EXCLUSIVE);
400 	if (error) {
401 		vrele(*vpp);
402 		*vpp = NULL;
403 		return error;
404 	}
405 	return 0;
406 }
407 
408 /*ARGSUSED*/
409 int
410 ptyfs_sync(struct mount *mp, int waitfor,
411     kauth_cred_t uc)
412 {
413 	return 0;
414 }
415 
416 /*
417  * Initialize this vnode / ptynode pair.
418  * Only for the slave side of a pty, caller assures
419  * no other thread will try to load this node.
420  */
421 int
422 ptyfs_loadvnode(struct mount *mp, struct vnode *vp,
423     const void *key, size_t key_len, const void **new_key)
424 {
425 	struct ptyfskey pkey;
426 	struct ptyfsnode *ptyfs;
427 
428 	KASSERT(key_len == sizeof(pkey));
429 	memcpy(&pkey, key, key_len);
430 
431 	ptyfs = ptyfs_get_node(pkey.ptk_type, pkey.ptk_pty);
432 	KASSERT(memcmp(&ptyfs->ptyfs_key, &pkey, sizeof(pkey)) == 0);
433 
434 	switch (pkey.ptk_type) {
435 	case PTYFSroot:	/* /pts = dr-xr-xr-x */
436 		vp->v_type = VDIR;
437 		vp->v_vflag = VV_ROOT;
438 		break;
439 
440 	case PTYFSpts:	/* /pts/N = cxxxxxxxxx */
441 	case PTYFSptc:	/* controlling side = cxxxxxxxxx */
442 		vp->v_type = VCHR;
443 		spec_node_init(vp, PTYFS_MAKEDEV(ptyfs));
444 		break;
445 	default:
446 		panic("ptyfs_loadvnode");
447 	}
448 
449 	vp->v_tag = VT_PTYFS;
450 	vp->v_op = ptyfs_vnodeop_p;
451 	vp->v_data = ptyfs;
452 	uvm_vnp_setsize(vp, 0);
453 	*new_key = &ptyfs->ptyfs_key;
454 	return 0;
455 }
456 
457 /*
458  * Kernfs flat namespace lookup.
459  * Currently unsupported.
460  */
461 /*ARGSUSED*/
462 int
463 ptyfs_vget(struct mount *mp, ino_t ino,
464     struct vnode **vpp)
465 {
466 	return EOPNOTSUPP;
467 }
468 
469 extern const struct vnodeopv_desc ptyfs_vnodeop_opv_desc;
470 
471 const struct vnodeopv_desc * const ptyfs_vnodeopv_descs[] = {
472 	&ptyfs_vnodeop_opv_desc,
473 	NULL,
474 };
475 
476 struct vfsops ptyfs_vfsops = {
477 	.vfs_name = MOUNT_PTYFS,
478 	.vfs_min_mount_data = sizeof (struct ptyfs_args),
479 	.vfs_mount = ptyfs_mount,
480 	.vfs_start = ptyfs_start,
481 	.vfs_unmount = ptyfs_unmount,
482 	.vfs_root = ptyfs_root,
483 	.vfs_quotactl = (void *)eopnotsupp,
484 	.vfs_statvfs = genfs_statvfs,
485 	.vfs_sync = ptyfs_sync,
486 	.vfs_vget = ptyfs_vget,
487 	.vfs_loadvnode = ptyfs_loadvnode,
488 	.vfs_fhtovp = (void *)eopnotsupp,
489 	.vfs_vptofh = (void *)eopnotsupp,
490 	.vfs_init = ptyfs_init,
491 	.vfs_reinit = ptyfs_reinit,
492 	.vfs_done = ptyfs_done,
493 	.vfs_snapshot = (void *)eopnotsupp,
494 	.vfs_extattrctl = (void *)eopnotsupp,
495 	.vfs_suspendctl = genfs_suspendctl,
496 	.vfs_renamelock_enter = genfs_renamelock_enter,
497 	.vfs_renamelock_exit = genfs_renamelock_exit,
498 	.vfs_fsync = (void *)eopnotsupp,
499 	.vfs_opv_descs = ptyfs_vnodeopv_descs
500 };
501 
502 static int
503 ptyfs_modcmd(modcmd_t cmd, void *arg)
504 {
505 	int error;
506 
507 	switch (cmd) {
508 	case MODULE_CMD_INIT:
509 		error = vfs_attach(&ptyfs_vfsops);
510 		if (error != 0)
511 			break;
512 		sysctl_createv(&ptyfs_sysctl_log, 0, NULL, NULL,
513 			       CTLFLAG_PERMANENT,
514 			       CTLTYPE_NODE, "ptyfs",
515 			       SYSCTL_DESCR("Pty file system"),
516 			       NULL, 0, NULL, 0,
517 			       CTL_VFS, 23, CTL_EOL);
518 		/*
519 		 * XXX the "23" above could be dynamic, thereby eliminating
520 		 * one more instance of the "number to vfs" mapping problem,
521 		 * but "23" is the order as taken from sys/mount.h
522 		 */
523 		break;
524 	case MODULE_CMD_FINI:
525 		error = vfs_detach(&ptyfs_vfsops);
526 		if (error != 0)
527 			break;
528 		sysctl_teardown(&ptyfs_sysctl_log);
529 		break;
530 	default:
531 		error = ENOTTY;
532 		break;
533 	}
534 
535 	return (error);
536 }
537