1 /* $NetBSD: vfs_init.c,v 1.67 2024/12/07 02:27:38 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 /*
34 * Copyright (c) 1989, 1993
35 * The Regents of the University of California. All rights reserved.
36 *
37 * This code is derived from software contributed
38 * to Berkeley by John Heidemann of the UCLA Ficus project.
39 *
40 * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
41 *
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions
44 * are met:
45 * 1. Redistributions of source code must retain the above copyright
46 * notice, this list of conditions and the following disclaimer.
47 * 2. Redistributions in binary form must reproduce the above copyright
48 * notice, this list of conditions and the following disclaimer in the
49 * documentation and/or other materials provided with the distribution.
50 * 3. Neither the name of the University nor the names of its contributors
51 * may be used to endorse or promote products derived from this software
52 * without specific prior written permission.
53 *
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
65 *
66 * @(#)vfs_init.c 8.5 (Berkeley) 5/11/95
67 */
68
69 #include <sys/cdefs.h>
70 __KERNEL_RCSID(0, "$NetBSD: vfs_init.c,v 1.67 2024/12/07 02:27:38 riastradh Exp $");
71
72 #include <sys/param.h>
73 #include <sys/types.h>
74
75 #include <sys/buf.h>
76 #include <sys/dirhash.h>
77 #include <sys/errno.h>
78 #include <sys/kauth.h>
79 #include <sys/kmem.h>
80 #include <sys/module.h>
81 #include <sys/mount.h>
82 #include <sys/namei.h>
83 #include <sys/sdt.h>
84 #include <sys/stat.h>
85 #include <sys/sysctl.h>
86 #include <sys/systm.h>
87 #include <sys/time.h>
88 #include <sys/ucred.h>
89 #include <sys/vnode.h>
90 #include <sys/vnode_impl.h>
91
92 #include <miscfs/deadfs/deadfs.h>
93 #include <miscfs/fifofs/fifo.h>
94 #include <miscfs/specfs/specdev.h>
95
96 /*
97 * Sigh, such primitive tools are these...
98 */
99 #if 0
100 #define DODEBUG(A) A
101 #else
102 #define DODEBUG(A) __nothing
103 #endif
104
105 SDT_PROVIDER_DEFINE(vfs);
106
107 /*
108 * These vnodeopv_descs are listed here because they are not
109 * associated with any particular file system, and thus cannot
110 * be initialized by vfs_attach().
111 */
112 const struct vnodeopv_desc * const vfs_special_vnodeopv_descs[] = {
113 &dead_vnodeop_opv_desc,
114 &fifo_vnodeop_opv_desc,
115 &spec_vnodeop_opv_desc,
116 NULL,
117 };
118
119 struct vfs_list_head vfs_list = /* vfs list */
120 LIST_HEAD_INITIALIZER(vfs_list);
121
122 static kauth_listener_t mount_listener;
123
124 /*
125 * This code doesn't work if the defn is **vnodop_defns with cc.
126 * The problem is because of the compiler sometimes putting in an
127 * extra level of indirection for arrays. It's an interesting
128 * "feature" of C.
129 */
130 typedef int (*PFI)(void *);
131
132 /*
133 * A miscellaneous routine.
134 * A generic "default" routine that just returns an error.
135 */
136 /*ARGSUSED*/
137 int
vn_default_error(void * v)138 vn_default_error(void *v)
139 {
140
141 return SET_ERROR(EOPNOTSUPP);
142 }
143
144 static struct sysctllog *vfs_sysctllog;
145
146 /*
147 * Top level filesystem related information gathering.
148 */
149 static void
sysctl_vfs_setup(void)150 sysctl_vfs_setup(void)
151 {
152
153 sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
154 CTLFLAG_PERMANENT,
155 CTLTYPE_NODE, "generic",
156 SYSCTL_DESCR("Non-specific vfs related information"),
157 NULL, 0, NULL, 0,
158 CTL_VFS, VFS_GENERIC, CTL_EOL);
159 sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
160 CTLFLAG_PERMANENT,
161 CTLTYPE_STRING, "fstypes",
162 SYSCTL_DESCR("List of file systems present"),
163 sysctl_vfs_generic_fstypes, 0, NULL, 0,
164 CTL_VFS, VFS_GENERIC, CTL_CREATE, CTL_EOL);
165 sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
166 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
167 CTLTYPE_INT, "magiclinks",
168 SYSCTL_DESCR("Whether \"magic\" symlinks are expanded"),
169 NULL, 0, &vfs_magiclinks, 0,
170 CTL_VFS, VFS_GENERIC, VFS_MAGICLINKS, CTL_EOL);
171 sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
172 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
173 CTLTYPE_INT, "timestamp_precision",
174 SYSCTL_DESCR("File timestamp precision"),
175 NULL, 0, &vfs_timestamp_precision, 0,
176 CTL_VFS, VFS_GENERIC, VFS_TIMESTAMP_PRECISION,
177 CTL_EOL);
178 }
179
180 /*
181 * vfs_init.c
182 *
183 * Allocate and fill in operations vectors.
184 *
185 * An undocumented feature of this approach to defining operations is that
186 * there can be multiple entries in vfs_opv_descs for the same operations
187 * vector. This allows third parties to extend the set of operations
188 * supported by another layer in a binary compatibile way. For example,
189 * assume that NFS needed to be modified to support Ficus. NFS has an entry
190 * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
191 * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
192 * listing those new operations Ficus adds to NFS, all without modifying the
193 * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
194 * that is a(whole)nother story.) This is a feature.
195 */
196
197 /*
198 * Init the vector, if it needs it.
199 * Also handle backwards compatibility.
200 */
201 static void
vfs_opv_init_explicit(const struct vnodeopv_desc * vfs_opv_desc)202 vfs_opv_init_explicit(const struct vnodeopv_desc *vfs_opv_desc)
203 {
204 int (**opv_desc_vector)(void *);
205 const struct vnodeopv_entry_desc *opve_descp;
206
207 opv_desc_vector = *(vfs_opv_desc->opv_desc_vector_p);
208
209 for (opve_descp = vfs_opv_desc->opv_desc_ops;
210 opve_descp->opve_op;
211 opve_descp++) {
212 /*
213 * Sanity check: is this operation listed
214 * in the list of operations? We check this
215 * by seeing if its offset is zero. Since
216 * the default routine should always be listed
217 * first, it should be the only one with a zero
218 * offset. Any other operation with a zero
219 * offset is probably not listed in
220 * vfs_op_descs, and so is probably an error.
221 *
222 * A panic here means the layer programmer
223 * has committed the all-too common bug
224 * of adding a new operation to the layer's
225 * list of vnode operations but
226 * not adding the operation to the system-wide
227 * list of supported operations.
228 */
229 if (opve_descp->opve_op->vdesc_offset == 0 &&
230 opve_descp->opve_op->vdesc_offset != VOFFSET(vop_default))
231 {
232 printf("operation %s not listed in %s.\n",
233 opve_descp->opve_op->vdesc_name, "vfs_op_descs");
234 panic("vfs_opv_init: bad operation");
235 }
236
237 /*
238 * Fill in this entry.
239 */
240 opv_desc_vector[opve_descp->opve_op->vdesc_offset] =
241 opve_descp->opve_impl;
242 }
243 }
244
245 static void
vfs_opv_init_default(const struct vnodeopv_desc * vfs_opv_desc)246 vfs_opv_init_default(const struct vnodeopv_desc *vfs_opv_desc)
247 {
248 int j;
249 int (**opv_desc_vector)(void *);
250
251 opv_desc_vector = *(vfs_opv_desc->opv_desc_vector_p);
252
253 /*
254 * Force every operations vector to have a default routine.
255 */
256 if (opv_desc_vector[VOFFSET(vop_default)] == NULL)
257 panic("vfs_opv_init: operation vector without vop_default");
258
259 for (j = 0; j < VNODE_OPS_COUNT; j++) {
260 if (opv_desc_vector[j] == NULL) {
261 opv_desc_vector[j] =
262 opv_desc_vector[VOFFSET(vop_default)];
263 }
264 }
265 }
266
267 void
vfs_opv_init(const struct vnodeopv_desc * const * vopvdpp)268 vfs_opv_init(const struct vnodeopv_desc * const *vopvdpp)
269 {
270 int (**opv_desc_vector)(void *);
271 int i;
272
273 /*
274 * Allocate the vectors.
275 */
276 for (i = 0; vopvdpp[i] != NULL; i++) {
277 opv_desc_vector =
278 kmem_alloc(VNODE_OPS_COUNT * sizeof(PFI), KM_SLEEP);
279 memset(opv_desc_vector, 0, VNODE_OPS_COUNT * sizeof(PFI));
280 *(vopvdpp[i]->opv_desc_vector_p) = opv_desc_vector;
281 DODEBUG(printf("vector at %p allocated\n",
282 opv_desc_vector_p));
283 }
284
285 /*
286 * ...and fill them in.
287 */
288 for (i = 0; vopvdpp[i] != NULL; i++)
289 vfs_opv_init_explicit(vopvdpp[i]);
290
291 /*
292 * Finally, go back and replace unfilled routines
293 * with their default.
294 */
295 for (i = 0; vopvdpp[i] != NULL; i++)
296 vfs_opv_init_default(vopvdpp[i]);
297 }
298
299 void
vfs_opv_free(const struct vnodeopv_desc * const * vopvdpp)300 vfs_opv_free(const struct vnodeopv_desc * const *vopvdpp)
301 {
302 int i;
303
304 /*
305 * Free the vectors allocated in vfs_opv_init().
306 */
307 for (i = 0; vopvdpp[i] != NULL; i++) {
308 kmem_free(*(vopvdpp[i]->opv_desc_vector_p),
309 VNODE_OPS_COUNT * sizeof(PFI));
310 *(vopvdpp[i]->opv_desc_vector_p) = NULL;
311 }
312 }
313
314 #ifdef DEBUG
315 static void
vfs_op_check(void)316 vfs_op_check(void)
317 {
318 int i;
319
320 DODEBUG(printf("Vnode_interface_init.\n"));
321
322 /*
323 * Check offset of each op.
324 */
325 for (i = 0; vfs_op_descs[i]; i++) {
326 if (vfs_op_descs[i]->vdesc_offset != i)
327 panic("vfs_op_check: vfs_op_desc[] offset mismatch");
328 }
329
330 if (i != VNODE_OPS_COUNT) {
331 panic("vfs_op_check: vnode ops count mismatch (%d != %d)",
332 i, VNODE_OPS_COUNT);
333 }
334
335 DODEBUG(printf ("vfs_opv_numops=%d\n", VNODE_OPS_COUNT));
336 }
337 #endif /* DEBUG */
338
339 /*
340 * Common routine to check if an unprivileged mount is allowed.
341 *
342 * We export just this part (i.e., without the access control) so that if a
343 * secmodel wants to implement finer grained user mounts it can do so without
344 * copying too much code. More elaborate policies (i.e., specific users allowed
345 * to also create devices and/or introduce set-id binaries, or export
346 * file-systems) will require a different implementation.
347 *
348 * This routine is intended to be called from listener context, and as such
349 * does not take credentials as an argument.
350 */
351 int
usermount_common_policy(struct mount * mp,u_long flags)352 usermount_common_policy(struct mount *mp, u_long flags)
353 {
354
355 /* No exporting if unprivileged. */
356 if (flags & MNT_EXPORTED)
357 return SET_ERROR(EPERM);
358
359 /* Must have 'nosuid' and 'nodev'. */
360 if ((flags & MNT_NODEV) == 0 || (flags & MNT_NOSUID) == 0)
361 return SET_ERROR(EPERM);
362
363 /* Retain 'noexec'. */
364 if ((mp->mnt_flag & MNT_NOEXEC) && (flags & MNT_NOEXEC) == 0)
365 return SET_ERROR(EPERM);
366
367 return 0;
368 }
369
370 static int
mount_listener_cb(kauth_cred_t cred,kauth_action_t action,void * cookie,void * arg0,void * arg1,void * arg2,void * arg3)371 mount_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
372 void *arg0, void *arg1, void *arg2, void *arg3)
373 {
374 int result;
375 enum kauth_system_req req;
376
377 result = KAUTH_RESULT_DEFER;
378 req = (enum kauth_system_req)(uintptr_t)(uintptr_t)arg0;
379
380 if (action != KAUTH_SYSTEM_MOUNT)
381 return result;
382
383 if (req == KAUTH_REQ_SYSTEM_MOUNT_GET)
384 result = KAUTH_RESULT_ALLOW;
385 else if (req == KAUTH_REQ_SYSTEM_MOUNT_DEVICE) {
386 vnode_t *devvp = arg2;
387 accmode_t accmode = (accmode_t)(unsigned long)arg3;
388 int error;
389
390 error = VOP_ACCESS(devvp, accmode, cred);
391 if (!error)
392 result = KAUTH_RESULT_ALLOW;
393 }
394
395 return result;
396 }
397
398 /*
399 * Initialize the vnode structures and initialize each file system type.
400 */
401 void
vfsinit(void)402 vfsinit(void)
403 {
404
405 /*
406 * Attach sysctl nodes
407 */
408 sysctl_vfs_setup();
409
410 /*
411 * Initialize the vnode table
412 */
413 vntblinit();
414
415 /*
416 * Initialize the vnode name cache
417 */
418 nchinit();
419
420 #ifdef DEBUG
421 /*
422 * Check the list of vnode operations.
423 */
424 vfs_op_check();
425 #endif
426
427 /*
428 * Initialize the special vnode operations.
429 */
430 vfs_opv_init(vfs_special_vnodeopv_descs);
431
432 /*
433 * Initialise generic dirhash.
434 */
435 dirhash_init();
436
437 /*
438 * Initialise VFS hooks.
439 */
440 vfs_hooks_init();
441
442 mount_listener = kauth_listen_scope(KAUTH_SCOPE_SYSTEM,
443 mount_listener_cb, NULL);
444
445 /*
446 * Establish each file system which was statically
447 * included in the kernel.
448 */
449 module_init_class(MODULE_CLASS_VFS);
450
451 /*
452 * Initialize EVFILT_FS for kqueue.
453 */
454 vfs_evfilt_fs_init();
455 }
456
457 /*
458 * Drop a reference to a file system type.
459 */
460 void
vfs_delref(struct vfsops * vfs)461 vfs_delref(struct vfsops *vfs)
462 {
463
464 mutex_enter(&vfs_list_lock);
465 vfs->vfs_refcount--;
466 mutex_exit(&vfs_list_lock);
467 }
468
469 /*
470 * Establish a file system and initialize it.
471 */
472 int
vfs_attach(struct vfsops * vfs)473 vfs_attach(struct vfsops *vfs)
474 {
475 struct vfsops *v;
476 int error = 0;
477
478 mutex_enter(&vfs_list_lock);
479
480 /*
481 * Make sure this file system doesn't already exist.
482 */
483 LIST_FOREACH(v, &vfs_list, vfs_list) {
484 if (strcmp(vfs->vfs_name, v->vfs_name) == 0) {
485 error = SET_ERROR(EEXIST);
486 goto out;
487 }
488 }
489
490 /*
491 * Initialize the vnode operations for this file system.
492 */
493 vfs_opv_init(vfs->vfs_opv_descs);
494
495 /*
496 * Now initialize the file system itself.
497 */
498 (*vfs->vfs_init)();
499
500 /*
501 * ...and link it into the kernel's list.
502 */
503 LIST_INSERT_HEAD(&vfs_list, vfs, vfs_list);
504
505 /*
506 * Sanity: make sure the reference count is 0.
507 */
508 vfs->vfs_refcount = 0;
509 out:
510 mutex_exit(&vfs_list_lock);
511 return error;
512 }
513
514 /*
515 * Remove a file system from the kernel.
516 */
517 int
vfs_detach(struct vfsops * vfs)518 vfs_detach(struct vfsops *vfs)
519 {
520 struct vfsops *v;
521 int error = 0;
522
523 mutex_enter(&vfs_list_lock);
524
525 /*
526 * Make sure no one is using the filesystem.
527 */
528 if (vfs->vfs_refcount != 0) {
529 error = SET_ERROR(EBUSY);
530 goto out;
531 }
532
533 /*
534 * ...and remove it from the kernel's list.
535 */
536 LIST_FOREACH(v, &vfs_list, vfs_list) {
537 if (v == vfs) {
538 LIST_REMOVE(v, vfs_list);
539 break;
540 }
541 }
542
543 if (v == NULL) {
544 error = SET_ERROR(ESRCH);
545 goto out;
546 }
547
548 /*
549 * Now run the file system-specific cleanups.
550 */
551 (*vfs->vfs_done)();
552
553 /*
554 * Free the vnode operations vector.
555 */
556 vfs_opv_free(vfs->vfs_opv_descs);
557 out:
558 mutex_exit(&vfs_list_lock);
559 return error;
560 }
561
562 void
vfs_reinit(void)563 vfs_reinit(void)
564 {
565 struct vfsops *vfs;
566
567 mutex_enter(&vfs_list_lock);
568 LIST_FOREACH(vfs, &vfs_list, vfs_list) {
569 if (vfs->vfs_reinit) {
570 vfs->vfs_refcount++;
571 mutex_exit(&vfs_list_lock);
572 (*vfs->vfs_reinit)();
573 mutex_enter(&vfs_list_lock);
574 vfs->vfs_refcount--;
575 }
576 }
577 mutex_exit(&vfs_list_lock);
578 }
579