xref: /linux/fs/nfsd/nfsfh.c (revision ba6e8564f459211117ce300eae2c7fdd23befe34) 
1 /*
2  * linux/fs/nfsd/nfsfh.c
3  *
4  * NFS server file handle treatment.
5  *
6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
7  * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
8  * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
9  * ... and again Southern-Winter 2001 to support export_operations
10  */
11 
12 #include <linux/slab.h>
13 #include <linux/smp_lock.h>
14 #include <linux/fs.h>
15 #include <linux/unistd.h>
16 #include <linux/string.h>
17 #include <linux/stat.h>
18 #include <linux/dcache.h>
19 #include <linux/mount.h>
20 
21 #include <linux/sunrpc/clnt.h>
22 #include <linux/sunrpc/svc.h>
23 #include <linux/nfsd/nfsd.h>
24 
25 #define NFSDDBG_FACILITY		NFSDDBG_FH
26 
27 
28 static int nfsd_nr_verified;
29 static int nfsd_nr_put;
30 
31 extern struct export_operations export_op_default;
32 
33 #define	CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
34 
35 /*
36  * our acceptability function.
37  * if NOSUBTREECHECK, accept anything
38  * if not, require that we can walk up to exp->ex_dentry
39  * doing some checks on the 'x' bits
40  */
41 static int nfsd_acceptable(void *expv, struct dentry *dentry)
42 {
43 	struct svc_export *exp = expv;
44 	int rv;
45 	struct dentry *tdentry;
46 	struct dentry *parent;
47 
48 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
49 		return 1;
50 
51 	tdentry = dget(dentry);
52 	while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
53 		/* make sure parents give x permission to user */
54 		int err;
55 		parent = dget_parent(tdentry);
56 		err = permission(parent->d_inode, MAY_EXEC, NULL);
57 		if (err < 0) {
58 			dput(parent);
59 			break;
60 		}
61 		dput(tdentry);
62 		tdentry = parent;
63 	}
64 	if (tdentry != exp->ex_dentry)
65 		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
66 	rv = (tdentry == exp->ex_dentry);
67 	dput(tdentry);
68 	return rv;
69 }
70 
71 /* Type check. The correct error return for type mismatches does not seem to be
72  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
73  * comment in the NFSv3 spec says this is incorrect (implementation notes for
74  * the write call).
75  */
76 static inline __be32
77 nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
78 {
79 	/* Type can be negative when creating hardlinks - not to a dir */
80 	if (type > 0 && (mode & S_IFMT) != type) {
81 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
82 			return nfserr_symlink;
83 		else if (type == S_IFDIR)
84 			return nfserr_notdir;
85 		else if ((mode & S_IFMT) == S_IFDIR)
86 			return nfserr_isdir;
87 		else
88 			return nfserr_inval;
89 	}
90 	if (type < 0 && (mode & S_IFMT) == -type) {
91 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
92 			return nfserr_symlink;
93 		else if (type == -S_IFDIR)
94 			return nfserr_isdir;
95 		else
96 			return nfserr_notdir;
97 	}
98 	return 0;
99 }
100 
101 /*
102  * Perform sanity checks on the dentry in a client's file handle.
103  *
104  * Note that the file handle dentry may need to be freed even after
105  * an error return.
106  *
107  * This is only called at the start of an nfsproc call, so fhp points to
108  * a svc_fh which is all 0 except for the over-the-wire file handle.
109  */
110 __be32
111 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
112 {
113 	struct knfsd_fh	*fh = &fhp->fh_handle;
114 	struct svc_export *exp = NULL;
115 	struct dentry	*dentry;
116 	__be32		error = 0;
117 
118 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
119 
120 	if (!fhp->fh_dentry) {
121 		__u32 *datap=NULL;
122 		__u32 tfh[3];		/* filehandle fragment for oldstyle filehandles */
123 		int fileid_type;
124 		int data_left = fh->fh_size/4;
125 
126 		error = nfserr_stale;
127 		if (rqstp->rq_client == NULL)
128 			goto out;
129 		if (rqstp->rq_vers > 2)
130 			error = nfserr_badhandle;
131 		if (rqstp->rq_vers == 4 && fh->fh_size == 0)
132 			return nfserr_nofilehandle;
133 
134 		if (fh->fh_version == 1) {
135 			int len;
136 			datap = fh->fh_auth;
137 			if (--data_left<0) goto out;
138 			switch (fh->fh_auth_type) {
139 			case 0: break;
140 			default: goto out;
141 			}
142 			len = key_len(fh->fh_fsid_type) / 4;
143 			if (len == 0) goto out;
144 			if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
145 				/* deprecated, convert to type 3 */
146 				len = key_len(FSID_ENCODE_DEV)/4;
147 				fh->fh_fsid_type = FSID_ENCODE_DEV;
148 				fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
149 				fh->fh_fsid[1] = fh->fh_fsid[2];
150 			}
151 			if ((data_left -= len)<0) goto out;
152 			exp = exp_find(rqstp->rq_client, fh->fh_fsid_type, datap, &rqstp->rq_chandle);
153 			datap += len;
154 		} else {
155 			dev_t xdev;
156 			ino_t xino;
157 			if (fh->fh_size != NFS_FHSIZE)
158 				goto out;
159 			/* assume old filehandle format */
160 			xdev = old_decode_dev(fh->ofh_xdev);
161 			xino = u32_to_ino_t(fh->ofh_xino);
162 			mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
163 			exp = exp_find(rqstp->rq_client, FSID_DEV, tfh,
164 				       &rqstp->rq_chandle);
165 		}
166 
167 		if (IS_ERR(exp) && (PTR_ERR(exp) == -EAGAIN
168 				|| PTR_ERR(exp) == -ETIMEDOUT)) {
169 			error = nfserrno(PTR_ERR(exp));
170 			goto out;
171 		}
172 
173 		error = nfserr_stale;
174 		if (!exp || IS_ERR(exp))
175 			goto out;
176 
177 		/* Check if the request originated from a secure port. */
178 		error = nfserr_perm;
179 		if (!rqstp->rq_secure && EX_SECURE(exp)) {
180 			char buf[RPC_MAX_ADDRBUFLEN];
181 			printk(KERN_WARNING
182 			       "nfsd: request from insecure port %s!\n",
183 			       svc_print_addr(rqstp, buf, sizeof(buf)));
184 			goto out;
185 		}
186 
187 		/* Set user creds for this exportpoint */
188 		error = nfserrno(nfsd_setuser(rqstp, exp));
189 		if (error)
190 			goto out;
191 
192 		/*
193 		 * Look up the dentry using the NFS file handle.
194 		 */
195 		error = nfserr_stale;
196 		if (rqstp->rq_vers > 2)
197 			error = nfserr_badhandle;
198 
199 		if (fh->fh_version != 1) {
200 			tfh[0] = fh->ofh_ino;
201 			tfh[1] = fh->ofh_generation;
202 			tfh[2] = fh->ofh_dirino;
203 			datap = tfh;
204 			data_left = 3;
205 			if (fh->ofh_dirino == 0)
206 				fileid_type = 1;
207 			else
208 				fileid_type = 2;
209 		} else
210 			fileid_type = fh->fh_fileid_type;
211 
212 		if (fileid_type == 0)
213 			dentry = dget(exp->ex_dentry);
214 		else {
215 			struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
216 			dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
217 						     datap, data_left,
218 						     fileid_type,
219 						     nfsd_acceptable, exp);
220 		}
221 		if (dentry == NULL)
222 			goto out;
223 		if (IS_ERR(dentry)) {
224 			if (PTR_ERR(dentry) != -EINVAL)
225 				error = nfserrno(PTR_ERR(dentry));
226 			goto out;
227 		}
228 
229 		if (S_ISDIR(dentry->d_inode->i_mode) &&
230 		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
231 			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
232 			       dentry->d_parent->d_name.name, dentry->d_name.name);
233 		}
234 
235 		fhp->fh_dentry = dentry;
236 		fhp->fh_export = exp;
237 		nfsd_nr_verified++;
238 	} else {
239 		/* just rechecking permissions
240 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
241 		 */
242 		dprintk("nfsd: fh_verify - just checking\n");
243 		dentry = fhp->fh_dentry;
244 		exp = fhp->fh_export;
245 		/* Set user creds for this exportpoint; necessary even
246 		 * in the "just checking" case because this may be a
247 		 * filehandle that was created by fh_compose, and that
248 		 * is about to be used in another nfsv4 compound
249 		 * operation */
250 		error = nfserrno(nfsd_setuser(rqstp, exp));
251 		if (error)
252 			goto out;
253 	}
254 	cache_get(&exp->h);
255 
256 
257 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
258 	if (error)
259 		goto out;
260 
261 	/* Finally, check access permissions. */
262 	error = nfsd_permission(exp, dentry, access);
263 
264 	if (error) {
265 		dprintk("fh_verify: %s/%s permission failure, "
266 			"acc=%x, error=%d\n",
267 			dentry->d_parent->d_name.name,
268 			dentry->d_name.name,
269 			access, ntohl(error));
270 	}
271 out:
272 	if (exp && !IS_ERR(exp))
273 		exp_put(exp);
274 	if (error == nfserr_stale)
275 		nfsdstats.fh_stale++;
276 	return error;
277 }
278 
279 
280 /*
281  * Compose a file handle for an NFS reply.
282  *
283  * Note that when first composed, the dentry may not yet have
284  * an inode.  In this case a call to fh_update should be made
285  * before the fh goes out on the wire ...
286  */
287 static inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
288 			     __u32 *datap, int *maxsize)
289 {
290 	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
291 
292 	if (dentry == exp->ex_dentry) {
293 		*maxsize = 0;
294 		return 0;
295 	}
296 
297 	return CALL(nop,encode_fh)(dentry, datap, maxsize,
298 			  !(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
299 }
300 
301 /*
302  * for composing old style file handles
303  */
304 static inline void _fh_update_old(struct dentry *dentry,
305 				  struct svc_export *exp,
306 				  struct knfsd_fh *fh)
307 {
308 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
309 	fh->ofh_generation = dentry->d_inode->i_generation;
310 	if (S_ISDIR(dentry->d_inode->i_mode) ||
311 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
312 		fh->ofh_dirino = 0;
313 }
314 
315 __be32
316 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
317 	   struct svc_fh *ref_fh)
318 {
319 	/* ref_fh is a reference file handle.
320 	 * if it is non-null and for the same filesystem, then we should compose
321 	 * a filehandle which is of the same version, where possible.
322 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
323 	 * Then create a 32byte filehandle using nfs_fhbase_old
324 	 *
325 	 */
326 
327 	u8 version = 1;
328 	u8 fsid_type = 0;
329 	struct inode * inode = dentry->d_inode;
330 	struct dentry *parent = dentry->d_parent;
331 	__u32 *datap;
332 	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
333 	int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);
334 
335 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
336 		MAJOR(ex_dev), MINOR(ex_dev),
337 		(long) exp->ex_dentry->d_inode->i_ino,
338 		parent->d_name.name, dentry->d_name.name,
339 		(inode ? inode->i_ino : 0));
340 
341 	/* Choose filehandle version and fsid type based on
342 	 * the reference filehandle (if it is in the same export)
343 	 * or the export options.
344 	 */
345 	if (ref_fh && ref_fh->fh_export == exp) {
346 		version = ref_fh->fh_handle.fh_version;
347 		if (version == 0xca)
348 			fsid_type = FSID_DEV;
349 		else
350 			fsid_type = ref_fh->fh_handle.fh_fsid_type;
351 		/* We know this version/type works for this export
352 		 * so there is no need for further checks.
353 		 */
354 	} else if (exp->ex_uuid) {
355 		if (fhp->fh_maxsize >= 64) {
356 			if (root_export)
357 				fsid_type = FSID_UUID16;
358 			else
359 				fsid_type = FSID_UUID16_INUM;
360 		} else {
361 			if (root_export)
362 				fsid_type = FSID_UUID8;
363 			else
364 				fsid_type = FSID_UUID4_INUM;
365 		}
366 	} else if (exp->ex_flags & NFSEXP_FSID)
367 		fsid_type = FSID_NUM;
368 	else if (!old_valid_dev(ex_dev))
369 		/* for newer device numbers, we must use a newer fsid format */
370 		fsid_type = FSID_ENCODE_DEV;
371 	else
372 		fsid_type = FSID_DEV;
373 
374 	if (ref_fh == fhp)
375 		fh_put(ref_fh);
376 
377 	if (fhp->fh_locked || fhp->fh_dentry) {
378 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
379 		       parent->d_name.name, dentry->d_name.name);
380 	}
381 	if (fhp->fh_maxsize < NFS_FHSIZE)
382 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
383 		       fhp->fh_maxsize,
384 		       parent->d_name.name, dentry->d_name.name);
385 
386 	fhp->fh_dentry = dget(dentry); /* our internal copy */
387 	fhp->fh_export = exp;
388 	cache_get(&exp->h);
389 
390 	if (version == 0xca) {
391 		/* old style filehandle please */
392 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
393 		fhp->fh_handle.fh_size = NFS_FHSIZE;
394 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
395 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
396 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
397 		fhp->fh_handle.ofh_xino =
398 			ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
399 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
400 		if (inode)
401 			_fh_update_old(dentry, exp, &fhp->fh_handle);
402 	} else {
403 		int len;
404 		fhp->fh_handle.fh_version = 1;
405 		fhp->fh_handle.fh_auth_type = 0;
406 		datap = fhp->fh_handle.fh_auth+0;
407 		fhp->fh_handle.fh_fsid_type = fsid_type;
408 		mk_fsid(fsid_type, datap, ex_dev,
409 			exp->ex_dentry->d_inode->i_ino,
410 			exp->ex_fsid, exp->ex_uuid);
411 
412 		len = key_len(fsid_type);
413 		datap += len/4;
414 		fhp->fh_handle.fh_size = 4 + len;
415 
416 		if (inode) {
417 			int size = (fhp->fh_maxsize-len-4)/4;
418 			fhp->fh_handle.fh_fileid_type =
419 				_fh_update(dentry, exp, datap, &size);
420 			fhp->fh_handle.fh_size += size*4;
421 		}
422 		if (fhp->fh_handle.fh_fileid_type == 255)
423 			return nfserr_opnotsupp;
424 	}
425 
426 	nfsd_nr_verified++;
427 	return 0;
428 }
429 
430 /*
431  * Update file handle information after changing a dentry.
432  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
433  */
434 __be32
435 fh_update(struct svc_fh *fhp)
436 {
437 	struct dentry *dentry;
438 	__u32 *datap;
439 
440 	if (!fhp->fh_dentry)
441 		goto out_bad;
442 
443 	dentry = fhp->fh_dentry;
444 	if (!dentry->d_inode)
445 		goto out_negative;
446 	if (fhp->fh_handle.fh_version != 1) {
447 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
448 	} else {
449 		int size;
450 		if (fhp->fh_handle.fh_fileid_type != 0)
451 			goto out;
452 		datap = fhp->fh_handle.fh_auth+
453 			fhp->fh_handle.fh_size/4 -1;
454 		size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
455 		fhp->fh_handle.fh_fileid_type =
456 			_fh_update(dentry, fhp->fh_export, datap, &size);
457 		fhp->fh_handle.fh_size += size*4;
458 		if (fhp->fh_handle.fh_fileid_type == 255)
459 			return nfserr_opnotsupp;
460 	}
461 out:
462 	return 0;
463 
464 out_bad:
465 	printk(KERN_ERR "fh_update: fh not verified!\n");
466 	goto out;
467 out_negative:
468 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
469 		dentry->d_parent->d_name.name, dentry->d_name.name);
470 	goto out;
471 }
472 
473 /*
474  * Release a file handle.
475  */
476 void
477 fh_put(struct svc_fh *fhp)
478 {
479 	struct dentry * dentry = fhp->fh_dentry;
480 	struct svc_export * exp = fhp->fh_export;
481 	if (dentry) {
482 		fh_unlock(fhp);
483 		fhp->fh_dentry = NULL;
484 		dput(dentry);
485 #ifdef CONFIG_NFSD_V3
486 		fhp->fh_pre_saved = 0;
487 		fhp->fh_post_saved = 0;
488 #endif
489 		nfsd_nr_put++;
490 	}
491 	if (exp) {
492 		cache_put(&exp->h, &svc_export_cache);
493 		fhp->fh_export = NULL;
494 	}
495 	return;
496 }
497 
498 /*
499  * Shorthand for dprintk()'s
500  */
501 char * SVCFH_fmt(struct svc_fh *fhp)
502 {
503 	struct knfsd_fh *fh = &fhp->fh_handle;
504 
505 	static char buf[80];
506 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
507 		fh->fh_size,
508 		fh->fh_base.fh_pad[0],
509 		fh->fh_base.fh_pad[1],
510 		fh->fh_base.fh_pad[2],
511 		fh->fh_base.fh_pad[3],
512 		fh->fh_base.fh_pad[4],
513 		fh->fh_base.fh_pad[5]);
514 	return buf;
515 }
516 
517 enum fsid_source fsid_source(struct svc_fh *fhp)
518 {
519 	if (fhp->fh_handle.fh_version != 1)
520 		return FSIDSOURCE_DEV;
521 	switch(fhp->fh_handle.fh_fsid_type) {
522 	case FSID_DEV:
523 	case FSID_ENCODE_DEV:
524 	case FSID_MAJOR_MINOR:
525 		return FSIDSOURCE_DEV;
526 	case FSID_NUM:
527 		return FSIDSOURCE_FSID;
528 	default:
529 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
530 			return FSIDSOURCE_FSID;
531 		else
532 			return FSIDSOURCE_UUID;
533 	}
534 }
535