1 /*
2 * Copyright (c) 1992, 1993, 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software donated to Berkeley by
6 * Jan-Simon Pendry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94
33 *
34 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
35 * $FreeBSD: src/sys/miscfs/nullfs/null_vfsops.c,v 1.35.2.3 2001/07/26 20:37:11 iedowse Exp $
36 * $DragonFly: src/sys/vfs/nullfs/null_vfsops.c,v 1.31 2008/09/17 21:44:25 dillon Exp $
37 */
38
39 /*
40 * Null Layer
41 * (See null_vnops.c for a description of what this does.)
42 */
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/proc.h>
48 #include <sys/malloc.h>
49 #include <sys/vnode.h>
50 #include <sys/mount.h>
51 #include <sys/namecache.h>
52 #include <sys/nlookup.h>
53 #include <sys/mountctl.h>
54 #include <sys/sysctl.h>
55 #include "null.h"
56
57 extern struct vop_ops null_vnode_vops;
58
59 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure");
60
61 SYSCTL_NODE(_vfs, OID_AUTO, nullfs, CTLFLAG_RD, 0, "NULLFS filesystem");
62
63 static int nullfs_debug;
64 TUNABLE_INT("vfs.nullfs.debug", &nullfs_debug);
65 SYSCTL_INT(_vfs_nullfs, OID_AUTO, debug, CTLFLAG_RW,
66 &nullfs_debug, 0, "nullfs debugging");
67
68 static int nullfs_root(struct mount *mp, struct vnode **vpp);
69 static int nullfs_statfs(struct mount *mp, struct statfs *sbp,
70 struct ucred *cred);
71
72 /*
73 * Mount null layer
74 */
75 static int
nullfs_mount(struct mount * mp,char * path,caddr_t data,struct ucred * cred)76 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
77 {
78 int error = 0;
79 struct null_args args;
80 struct vnode *rootvp;
81 struct null_mount *xmp;
82 size_t size;
83 struct nlookupdata nd;
84 fhandle_t fh;
85
86 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
87
88 /*
89 * Get argument
90 */
91 error = copyin(data, (caddr_t)&args, sizeof(struct null_args));
92 if (error)
93 return (error);
94
95 /*
96 * XXX: Should we process mount export info ?
97 * If not, returning zero here is enough as the actual ro/rw update is
98 * being done in sys_mount().
99 */
100 if (mp->mnt_flag & MNT_UPDATE) {
101 xmp = MOUNTTONULLMOUNT(mp);
102 error = vfs_export(mp, &xmp->export, &args.export);
103 return (error);
104 }
105
106 /*
107 * Find lower node
108 */
109 rootvp = NULL;
110 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW);
111 if (error)
112 goto fail1;
113 error = nlookup(&nd);
114 if (error)
115 goto fail2;
116 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp);
117 if (error)
118 goto fail2;
119
120 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount),
121 M_NULLFSMNT, M_WAITOK | M_ZERO);
122
123 /*
124 * Save reference to underlying FS
125 *
126 * As lite stacking enters the scene, the old way of doing this
127 * -- via the vnode -- is not good enough anymore. Use the
128 * underlying filesystem's namecache handle as our mount point
129 * root, adjusting the mount to point to us.
130 *
131 * NCF_ISMOUNTPT is normally set on the mount point, but we also
132 * want to set it on the base directory being mounted to prevent
133 * that directory from being destroyed out from under the nullfs
134 * mount.
135 *
136 * The forwarding mount pointer (xmp->nullm_vfs) must be set to
137 * the actual target filesystem. If the target filesystem was
138 * resolved via a nullfs mount nd.nl_nch.mount will be pointing
139 * to the nullfs mount structure instead of the target filesystem,
140 * which would otherwise cause the mount VOPS and VFSOPS to recurse
141 * endlessly. If we are mounting via a nullfs mount we inherit
142 * its read-only state, if set.
143 */
144 xmp->nullm_vfs = nd.nl_nch.mount;
145 if (xmp->nullm_vfs != rootvp->v_mount) {
146 if (xmp->nullm_vfs->mnt_flag & MNT_RDONLY)
147 mp->mnt_flag |= MNT_RDONLY;
148 if (xmp->nullm_vfs->mnt_flag & MNT_NOEXEC)
149 mp->mnt_flag |= MNT_NOEXEC;
150 xmp->nullm_vfs = rootvp->v_mount;
151 }
152
153 /*
154 * ncmountpt is the parent glue. When mounting a nullfs via a nullfs
155 * we retain the parent nullfs to create a unique chain tuple.
156 */
157 mp->mnt_ncmountpt = nd.nl_nch;
158 cache_changemount(&mp->mnt_ncmountpt, mp);
159 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT;
160 cache_unlock(&mp->mnt_ncmountpt);
161 cache_zero(&nd.nl_nch);
162 nlookup_done(&nd);
163
164 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops);
165
166 vn_unlock(rootvp); /* leave reference intact */
167
168 /*
169 * Keep a held reference to the root vnode.
170 * It is vrele'd in nullfs_unmount.
171 */
172 xmp->nullm_rootvp = rootvp;
173 /*
174 * XXX What's the proper safety condition for querying
175 * the underlying mount? Is this flag tuning necessary
176 * at all?
177 */
178 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL)
179 mp->mnt_flag |= MNT_LOCAL;
180 mp->mnt_data = (qaddr_t) xmp;
181
182 /*
183 * Mount path
184 */
185 copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, &size);
186
187 /*
188 * Try to create a unique but non-random fsid for the nullfs to
189 * allow it to be exported via NFS. Use a combination of the
190 * FH for the nullfs root in the underlying filesystem and a
191 * CRC of the null mount path.
192 *
193 * Use val[1] so as not to interfere with the generally unique
194 * val[0].
195 */
196 bzero(&fh, sizeof(fh));
197 fh.fh_fsid = rootvp->v_mount->mnt_stat.f_fsid;
198
199 if (VFS_VPTOFH(rootvp, &fh.fh_fid) == 0) {
200 if (nullfs_debug)
201 kprintf("(A)");
202 vfs_setfsid(mp, &fh.fh_fsid);
203 } else {
204 if (nullfs_debug)
205 kprintf("(B)");
206 vfs_getnewfsid(mp);
207 }
208 fh.fh_fsid.val[1] ^= crc32(mp->mnt_stat.f_mntfromname, size);
209
210 if (nullfs_debug) {
211 kprintf("NULLFS FSID %08x.%08x -> %08x.%08x (%*.*s)\n",
212 rootvp->v_mount->mnt_stat.f_fsid.val[0],
213 rootvp->v_mount->mnt_stat.f_fsid.val[1],
214 fh.fh_fsid.val[0],
215 fh.fh_fsid.val[1],
216 (int)size, (int)size, mp->mnt_stat.f_mntfromname);
217 }
218
219 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
220 nullfs_statfs(mp, &mp->mnt_stat, cred);
221 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
222 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname);
223
224 bzero(mp->mnt_stat.f_mntonname, MNAMELEN);
225 if (path != NULL) {
226 (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1,
227 &size);
228 }
229
230 /*
231 * Set NCALIASED so unmount won't complain about namecache refs
232 * still existing.
233 *
234 * All NULLFS operations are MPSAFE, though it will be short-lived
235 * if the underlying filesystem is not.
236 *
237 * NOTE: There is no syncer thread for nullfs (flagged in vfsops)
238 */
239 mp->mnt_kern_flag |= MNTK_NCALIASED | MNTK_ALL_MPSAFE;
240
241 return (0);
242 fail2:
243 nlookup_done(&nd);
244 fail1:
245 return (error);
246 }
247
248 /*
249 * Free reference to null layer
250 */
251 static int
nullfs_unmount(struct mount * mp,int mntflags)252 nullfs_unmount(struct mount *mp, int mntflags)
253 {
254 struct null_mount *xmp;
255
256 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
257
258 /*
259 * Throw away the null_mount structure
260 */
261 xmp = (void *)mp->mnt_data;
262 mp->mnt_data = 0;
263 if (xmp->nullm_rootvp) {
264 vrele(xmp->nullm_rootvp);
265 xmp->nullm_rootvp = NULL;
266 }
267 kfree(xmp, M_NULLFSMNT);
268 return 0;
269 }
270
271 static int
nullfs_root(struct mount * mp,struct vnode ** vpp)272 nullfs_root(struct mount *mp, struct vnode **vpp)
273 {
274 struct vnode *vp;
275 int error;
276
277 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp,
278 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
279
280 /*
281 * Return locked reference to root.
282 */
283 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
284 error = vget(vp, LK_EXCLUSIVE | LK_RETRY);
285 if (error == 0)
286 *vpp = vp;
287 return (error);
288 }
289
290 static int
nullfs_quotactl(struct mount * mp,int cmd,uid_t uid,caddr_t arg,struct ucred * cred)291 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg,
292 struct ucred *cred)
293 {
294 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred);
295 }
296
297 static int
nullfs_statfs(struct mount * mp,struct statfs * sbp,struct ucred * cred)298 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
299 {
300 int error;
301 struct statfs mstat;
302
303 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp,
304 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp);
305
306 bzero(&mstat, sizeof(mstat));
307
308 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred);
309 if (error)
310 return (error);
311
312 /* now copy across the "interesting" information and fake the rest */
313 sbp->f_type = mstat.f_type;
314 sbp->f_flags = mstat.f_flags;
315 sbp->f_bsize = mstat.f_bsize;
316 sbp->f_iosize = mstat.f_iosize;
317 sbp->f_blocks = mstat.f_blocks;
318 sbp->f_bfree = mstat.f_bfree;
319 sbp->f_bavail = mstat.f_bavail;
320 sbp->f_files = mstat.f_files;
321 sbp->f_ffree = mstat.f_ffree;
322 if (sbp != &mp->mnt_stat) {
323 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
324 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
325 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
326 }
327 return (0);
328 }
329
330 /*
331 * Implement NFS export tracking
332 */
333 static int
nullfs_checkexp(struct mount * mp,struct sockaddr * nam,int * extflagsp,struct ucred ** credanonp)334 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
335 struct ucred **credanonp)
336 {
337 struct null_mount *xmp = (void *)mp->mnt_data;
338 struct netcred *np;
339 int error;
340
341 np = vfs_export_lookup(mp, &xmp->export, nam);
342 if (np) {
343 *extflagsp = np->netc_exflags;
344 *credanonp = &np->netc_anon;
345 error = 0;
346 } else {
347 error = EACCES;
348 }
349 return(error);
350 #if 0
351 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam,
352 extflagsp, credanonp);
353 #endif
354 }
355
356 int
nullfs_export(struct mount * mp,int op,const struct export_args * export)357 nullfs_export(struct mount *mp, int op, const struct export_args *export)
358 {
359 struct null_mount *xmp = (void *)mp->mnt_data;
360 int error;
361
362 switch(op) {
363 case MOUNTCTL_SET_EXPORT:
364 error = vfs_export(mp, &xmp->export, export);
365 break;
366 default:
367 error = EOPNOTSUPP;
368 break;
369 }
370 return(error);
371 }
372
373 /*
374 * Pass through file handle conversion functions.
375 */
376 static int
nullfs_vptofh(struct vnode * vp,struct fid * fhp)377 nullfs_vptofh(struct vnode *vp, struct fid *fhp)
378 {
379 return VFS_VPTOFH(vp, fhp);
380 }
381
382 /*
383 * Pass through file handle conversion functions.
384 *
385 * NOTE: currently only HAMMER uses rootvp. HAMMER uses rootvp only
386 * to enforce PFS isolation.
387 */
388 static int
nullfs_fhtovp(struct mount * mp,struct vnode * rootvp,struct fid * fhp,struct vnode ** vpp)389 nullfs_fhtovp(struct mount *mp, struct vnode *rootvp,
390 struct fid *fhp, struct vnode **vpp)
391 {
392 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
393
394 return VFS_FHTOVP(xmp->nullm_vfs, xmp->nullm_rootvp, fhp, vpp);
395 }
396
397 static int
nullfs_extattrctl(struct mount * mp,int cmd,struct vnode * vp,int attrnamespace,const char * attrname,struct ucred * cred)398 nullfs_extattrctl(struct mount *mp, int cmd, struct vnode *vp,
399 int attrnamespace, const char *attrname, struct ucred *cred)
400 {
401 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd,
402 vp, attrnamespace, attrname, cred);
403 }
404
405 static void
nullfs_ncpgen_set(struct mount * mp,struct namecache * ncp)406 nullfs_ncpgen_set(struct mount *mp, struct namecache *ncp)
407 {
408 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
409
410 VFS_NCPGEN_SET(xmp->nullm_vfs, ncp);
411 }
412
413
414 static int
nullfs_ncpgen_test(struct mount * mp,struct namecache * ncp)415 nullfs_ncpgen_test(struct mount *mp, struct namecache *ncp)
416 {
417 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
418
419 return VFS_NCPGEN_TEST(xmp->nullm_vfs, ncp);
420 }
421
422 static int
nullfs_modifying(struct mount * mp)423 nullfs_modifying(struct mount *mp)
424 {
425 struct null_mount *xmp = MOUNTTONULLMOUNT(mp);
426 int error;
427
428 if (mp->mnt_flag & MNT_RDONLY)
429 error = EROFS;
430 else if (xmp->nullm_vfs)
431 error = VFS_MODIFYING(xmp->nullm_vfs);
432 else
433 error = 0;
434 return error;
435 }
436
437 static struct vfsops null_vfsops = {
438 .vfs_flags = VFSOPSF_NOSYNCERTHR,
439 .vfs_mount = nullfs_mount,
440 .vfs_unmount = nullfs_unmount,
441 .vfs_root = nullfs_root,
442 .vfs_quotactl = nullfs_quotactl,
443 .vfs_statfs = nullfs_statfs,
444 .vfs_extattrctl = nullfs_extattrctl,
445 .vfs_fhtovp = nullfs_fhtovp,
446 .vfs_vptofh = nullfs_vptofh,
447 .vfs_ncpgen_set = nullfs_ncpgen_set,
448 .vfs_ncpgen_test = nullfs_ncpgen_test,
449 .vfs_checkexp = nullfs_checkexp,
450 .vfs_modifying = nullfs_modifying
451 };
452
453 VFS_SET(null_vfsops, null, VFCF_LOOPBACK | VFCF_MPSAFE);
454 MODULE_VERSION(null, 1);
455