1 /* $NetBSD: ptyfs_vfsops.c,v 1.58 2020/03/16 21:20:10 pgoyette 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 1.58 2020/03/16 21:20:10 pgoyette 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 int ptyfs__allocvp(struct mount *, struct lwp *, struct vnode **,
74 dev_t, char);
75 static int ptyfs__makename(struct mount *, struct lwp *, char *, size_t,
76 dev_t, char);
77 static void ptyfs__getvattr(struct mount *, struct lwp *, struct vattr *);
78 static int ptyfs__getmp(struct lwp *, struct mount **);
79
80 /*
81 * ptm glue: When we mount, we make ptm point to us.
82 */
83 struct ptm_pty *ptyfs_save_ptm;
84 static int ptyfs_count;
85
86 static TAILQ_HEAD(, ptyfsmount) ptyfs_head;
87
88 struct ptm_pty ptm_ptyfspty = {
89 ptyfs__allocvp,
90 ptyfs__makename,
91 ptyfs__getvattr,
92 ptyfs__getmp,
93 };
94
95 static int
ptyfs__getmp(struct lwp * l,struct mount ** mpp)96 ptyfs__getmp(struct lwp *l, struct mount **mpp)
97 {
98 struct cwdinfo *cwdi = l->l_proc->p_cwdi;
99 struct mount *mp;
100 struct ptyfsmount *pmnt;
101
102 TAILQ_FOREACH(pmnt, &ptyfs_head, pmnt_le) {
103 mp = pmnt->pmnt_mp;
104 if (cwdi->cwdi_rdir == NULL)
105 goto ok;
106
107 if (vn_isunder(mp->mnt_vnodecovered, cwdi->cwdi_rdir, l))
108 goto ok;
109 }
110 *mpp = NULL;
111 return EOPNOTSUPP;
112 ok:
113 *mpp = mp;
114 return 0;
115 }
116
117 static const char *
ptyfs__getpath(struct lwp * l,const struct mount * mp)118 ptyfs__getpath(struct lwp *l, const struct mount *mp)
119 {
120 #define MAXBUF (sizeof(mp->mnt_stat.f_mntonname) + 32)
121 struct cwdinfo *cwdi = l->l_proc->p_cwdi;
122 char *buf;
123 const char *rv;
124 size_t len;
125 char *bp;
126 int error;
127
128 rv = mp->mnt_stat.f_mntonname;
129 if (cwdi->cwdi_rdir == NULL)
130 return rv;
131
132 buf = malloc(MAXBUF, M_TEMP, M_WAITOK);
133 bp = buf + MAXBUF;
134 *--bp = '\0';
135 error = getcwd_common(mp->mnt_vnodecovered, cwdi->cwdi_rdir, &bp,
136 buf, MAXBUF / 2, 0, l);
137 if (error) { /* Mount point is out of rdir */
138 rv = NULL;
139 goto out;
140 }
141
142 len = strlen(bp);
143 if (len < sizeof(mp->mnt_stat.f_mntonname)) /* XXX */
144 rv += strlen(rv) - len;
145 out:
146 free(buf, M_TEMP);
147 return rv;
148 }
149
150 static int
ptyfs__makename(struct mount * mp,struct lwp * l,char * tbuf,size_t bufsiz,dev_t dev,char ms)151 ptyfs__makename(struct mount *mp, struct lwp *l, char *tbuf, size_t bufsiz,
152 dev_t dev, char ms)
153 {
154 size_t len;
155 const char *np;
156 int pty = minor(dev);
157
158 switch (ms) {
159 case 'p':
160 /* We don't provide access to the master, should we? */
161 len = snprintf(tbuf, bufsiz, "/dev/null");
162 break;
163 case 't':
164 /*
165 * We support traditional ptys, so we can get here,
166 * if pty had been opened before PTYFS was mounted,
167 * or was opened through /dev/ptyXX devices.
168 * Return it only outside chroot for more security .
169 */
170 if (l->l_proc->p_cwdi->cwdi_rdir == NULL
171 && ptyfs_save_ptm != NULL
172 && ptyfs_next_active(mp, pty) != pty)
173 return (*ptyfs_save_ptm->makename)(mp, l,
174 tbuf, bufsiz, dev, ms);
175
176 np = ptyfs__getpath(l, mp);
177 if (np == NULL)
178 return EOPNOTSUPP;
179 len = snprintf(tbuf, bufsiz, "%s/%llu", np,
180 (unsigned long long)minor(dev));
181 break;
182 default:
183 return EINVAL;
184 }
185
186 return len >= bufsiz ? ENOSPC : 0;
187 }
188
189
190 static int
191 /*ARGSUSED*/
ptyfs__allocvp(struct mount * mp,struct lwp * l,struct vnode ** vpp,dev_t dev,char ms)192 ptyfs__allocvp(struct mount *mp, struct lwp *l, struct vnode **vpp,
193 dev_t dev, char ms)
194 {
195 int error;
196 ptyfstype type;
197
198 switch (ms) {
199 case 'p':
200 type = PTYFSptc;
201 break;
202 case 't':
203 type = PTYFSpts;
204 break;
205 default:
206 return EINVAL;
207 }
208
209 error = ptyfs_allocvp(mp, vpp, type, minor(dev));
210 if (error)
211 return error;
212 error = vn_lock(*vpp, LK_EXCLUSIVE);
213 if (error) {
214 vrele(*vpp);
215 *vpp = NULL;
216 return error;
217 }
218 if (type == PTYFSptc)
219 ptyfs_set_active(mp, minor(dev));
220 return 0;
221 }
222
223
224 static void
ptyfs__getvattr(struct mount * mp,struct lwp * l,struct vattr * vattr)225 ptyfs__getvattr(struct mount *mp, struct lwp *l, struct vattr *vattr)
226 {
227 struct ptyfsmount *pmnt = VFSTOPTY(mp);
228 vattr_null(vattr);
229 /* get real uid */
230 vattr->va_uid = kauth_cred_getuid(l->l_cred);
231 vattr->va_gid = pmnt->pmnt_gid;
232 vattr->va_mode = pmnt->pmnt_mode;
233 }
234
235
236 void
ptyfs_init(void)237 ptyfs_init(void)
238 {
239
240 TAILQ_INIT(&ptyfs_head);
241 malloc_type_attach(M_PTYFSMNT);
242 malloc_type_attach(M_PTYFSTMP);
243 ptyfs_hashinit();
244 }
245
246 void
ptyfs_reinit(void)247 ptyfs_reinit(void)
248 {
249
250 }
251
252 void
ptyfs_done(void)253 ptyfs_done(void)
254 {
255
256 ptyfs_hashdone();
257 malloc_type_detach(M_PTYFSTMP);
258 malloc_type_detach(M_PTYFSMNT);
259 }
260
261 #define OSIZE sizeof(struct { int f; gid_t g; mode_t m; })
262 /*
263 * Mount the Pseudo tty params filesystem
264 */
265 int
ptyfs_mount(struct mount * mp,const char * path,void * data,size_t * data_len)266 ptyfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
267 {
268 struct lwp *l = curlwp;
269 int error = 0;
270 struct ptyfsmount *pmnt;
271 struct ptyfs_args *args = data;
272
273 if (args == NULL)
274 return EINVAL;
275 if (*data_len != sizeof *args) {
276 if (*data_len != OSIZE || args->version >= PTYFS_ARGSVERSION)
277 return EINVAL;
278 }
279
280 if (UIO_MX & (UIO_MX - 1)) {
281 log(LOG_ERR, "ptyfs: invalid directory entry size");
282 return EINVAL;
283 }
284
285 if (mp->mnt_flag & MNT_GETARGS) {
286 pmnt = VFSTOPTY(mp);
287 if (pmnt == NULL)
288 return EIO;
289 args->mode = pmnt->pmnt_mode;
290 args->gid = pmnt->pmnt_gid;
291 if (args->version >= PTYFS_ARGSVERSION) {
292 args->flags = pmnt->pmnt_flags;
293 *data_len = sizeof *args;
294 } else {
295 *data_len = OSIZE;
296 }
297 return 0;
298 }
299
300 #if 0
301 /* Don't allow more than one mount */
302 if (ptyfs_count)
303 return EBUSY;
304 #endif
305
306 if (mp->mnt_flag & MNT_UPDATE)
307 return EOPNOTSUPP;
308
309 if (args->version > PTYFS_ARGSVERSION)
310 return EINVAL;
311
312 pmnt = malloc(sizeof(struct ptyfsmount), M_PTYFSMNT, M_WAITOK);
313
314 mp->mnt_data = pmnt;
315 mutex_init(&pmnt->pmnt_lock, MUTEX_DEFAULT, IPL_NONE);
316 pmnt->pmnt_gid = args->gid;
317 pmnt->pmnt_mode = args->mode;
318 if (args->version >= PTYFS_ARGSVERSION)
319 pmnt->pmnt_flags = args->flags;
320 else
321 pmnt->pmnt_flags = 0;
322 pmnt->pmnt_bitmap_size = 0;
323 pmnt->pmnt_bitmap = NULL;
324 mp->mnt_flag |= MNT_LOCAL;
325 vfs_getnewfsid(mp);
326
327 if ((error = set_statvfs_info(path, UIO_USERSPACE, "ptyfs",
328 UIO_SYSSPACE, mp->mnt_op->vfs_name, mp, l)) != 0) {
329 free(pmnt, M_PTYFSMNT);
330 return error;
331 }
332
333 pmnt->pmnt_mp = mp;
334 TAILQ_INSERT_TAIL(&ptyfs_head, pmnt, pmnt_le);
335 if (ptyfs_count++ == 0) {
336 /* Point pty access to us */
337 ptyfs_save_ptm = pty_sethandler(&ptm_ptyfspty);
338 }
339 return 0;
340 }
341
342 /*ARGSUSED*/
343 int
ptyfs_start(struct mount * mp,int flags)344 ptyfs_start(struct mount *mp, int flags)
345 {
346 return 0;
347 }
348
349 /*ARGSUSED*/
350 int
ptyfs_unmount(struct mount * mp,int mntflags)351 ptyfs_unmount(struct mount *mp, int mntflags)
352 {
353 int error;
354 int flags = 0;
355 struct ptyfsmount *pmnt;
356
357 if (mntflags & MNT_FORCE)
358 flags |= FORCECLOSE;
359
360 if ((error = vflush(mp, 0, flags)) != 0)
361 return error;
362
363 ptyfs_count--;
364 if (ptyfs_count == 0) {
365 /* Restore where pty access was pointing */
366 (void)pty_sethandler(ptyfs_save_ptm);
367 ptyfs_save_ptm = NULL;
368 }
369 TAILQ_FOREACH(pmnt, &ptyfs_head, pmnt_le) {
370 if (pmnt->pmnt_mp == mp) {
371 TAILQ_REMOVE(&ptyfs_head, pmnt, pmnt_le);
372 break;
373 }
374 }
375
376 /*
377 * Finally, throw away the ptyfsmount structure
378 */
379 if (pmnt->pmnt_bitmap_size > 0)
380 kmem_free(pmnt->pmnt_bitmap, pmnt->pmnt_bitmap_size);
381 mutex_destroy(&pmnt->pmnt_lock);
382 free(mp->mnt_data, M_PTYFSMNT);
383 mp->mnt_data = NULL;
384
385 return 0;
386 }
387
388 int
ptyfs_root(struct mount * mp,int lktype,struct vnode ** vpp)389 ptyfs_root(struct mount *mp, int lktype, struct vnode **vpp)
390 {
391 int error;
392
393 /* setup "." */
394 error = ptyfs_allocvp(mp, vpp, PTYFSroot, 0);
395 if (error)
396 return error;
397 error = vn_lock(*vpp, lktype);
398 if (error) {
399 vrele(*vpp);
400 *vpp = NULL;
401 return error;
402 }
403 return 0;
404 }
405
406 /*ARGSUSED*/
407 int
ptyfs_sync(struct mount * mp,int waitfor,kauth_cred_t uc)408 ptyfs_sync(struct mount *mp, int waitfor,
409 kauth_cred_t uc)
410 {
411 return 0;
412 }
413
414 /*
415 * Initialize this vnode / ptynode pair.
416 * Only for the slave side of a pty, caller assures
417 * no other thread will try to load this node.
418 */
419 int
ptyfs_loadvnode(struct mount * mp,struct vnode * vp,const void * key,size_t key_len,const void ** new_key)420 ptyfs_loadvnode(struct mount *mp, struct vnode *vp,
421 const void *key, size_t key_len, const void **new_key)
422 {
423 struct ptyfskey pkey;
424 struct ptyfsnode *ptyfs;
425
426 KASSERT(key_len == sizeof(pkey));
427 memcpy(&pkey, key, key_len);
428
429 ptyfs = ptyfs_get_node(pkey.ptk_type, pkey.ptk_pty);
430 KASSERT(memcmp(&ptyfs->ptyfs_key, &pkey, sizeof(pkey)) == 0);
431
432 switch (pkey.ptk_type) {
433 case PTYFSroot: /* /pts = dr-xr-xr-x */
434 vp->v_type = VDIR;
435 vp->v_vflag = VV_ROOT;
436 break;
437
438 case PTYFSpts: /* /pts/N = cxxxxxxxxx */
439 case PTYFSptc: /* controlling side = cxxxxxxxxx */
440 vp->v_type = VCHR;
441 spec_node_init(vp, PTYFS_MAKEDEV(ptyfs));
442 break;
443 default:
444 panic("ptyfs_loadvnode");
445 }
446
447 vp->v_tag = VT_PTYFS;
448 vp->v_op = ptyfs_vnodeop_p;
449 vp->v_data = ptyfs;
450 uvm_vnp_setsize(vp, 0);
451 *new_key = &ptyfs->ptyfs_key;
452 return 0;
453 }
454
455 /*
456 * Kernfs flat namespace lookup.
457 * Currently unsupported.
458 */
459 /*ARGSUSED*/
460 int
ptyfs_vget(struct mount * mp,ino_t ino,int lktype,struct vnode ** vpp)461 ptyfs_vget(struct mount *mp, ino_t ino, int lktype,
462 struct vnode **vpp)
463 {
464 return EOPNOTSUPP;
465 }
466
467 extern const struct vnodeopv_desc ptyfs_vnodeop_opv_desc;
468
469 const struct vnodeopv_desc * const ptyfs_vnodeopv_descs[] = {
470 &ptyfs_vnodeop_opv_desc,
471 NULL,
472 };
473
474 struct vfsops ptyfs_vfsops = {
475 .vfs_name = MOUNT_PTYFS,
476 .vfs_min_mount_data = sizeof (struct ptyfs_args),
477 .vfs_mount = ptyfs_mount,
478 .vfs_start = ptyfs_start,
479 .vfs_unmount = ptyfs_unmount,
480 .vfs_root = ptyfs_root,
481 .vfs_quotactl = (void *)eopnotsupp,
482 .vfs_statvfs = genfs_statvfs,
483 .vfs_sync = ptyfs_sync,
484 .vfs_vget = ptyfs_vget,
485 .vfs_loadvnode = ptyfs_loadvnode,
486 .vfs_fhtovp = (void *)eopnotsupp,
487 .vfs_vptofh = (void *)eopnotsupp,
488 .vfs_init = ptyfs_init,
489 .vfs_reinit = ptyfs_reinit,
490 .vfs_done = ptyfs_done,
491 .vfs_snapshot = (void *)eopnotsupp,
492 .vfs_extattrctl = (void *)eopnotsupp,
493 .vfs_suspendctl = genfs_suspendctl,
494 .vfs_renamelock_enter = genfs_renamelock_enter,
495 .vfs_renamelock_exit = genfs_renamelock_exit,
496 .vfs_fsync = (void *)eopnotsupp,
497 .vfs_opv_descs = ptyfs_vnodeopv_descs
498 };
499
500 SYSCTL_SETUP(ptyfs_sysctl_setup, "ptyfs sysctl")
501 {
502
503 sysctl_createv(clog, 0, NULL, NULL,
504 CTLFLAG_PERMANENT,
505 CTLTYPE_NODE, "ptyfs",
506 SYSCTL_DESCR("Pty file system"),
507 NULL, 0, NULL, 0,
508 CTL_VFS, 23, CTL_EOL);
509 /*
510 * XXX the "23" above could be dynamic, thereby eliminating
511 * one more instance of the "number to vfs" mapping problem,
512 * but "23" is the order as taken from sys/mount.h
513 */
514 }
515
516 static int
ptyfs_modcmd(modcmd_t cmd,void * arg)517 ptyfs_modcmd(modcmd_t cmd, void *arg)
518 {
519 int error;
520
521 switch (cmd) {
522 case MODULE_CMD_INIT:
523 error = vfs_attach(&ptyfs_vfsops);
524 if (error != 0)
525 break;
526 break;
527 case MODULE_CMD_FINI:
528 error = vfs_detach(&ptyfs_vfsops);
529 if (error != 0)
530 break;
531 break;
532 default:
533 error = ENOTTY;
534 break;
535 }
536
537 return (error);
538 }
539