xref: /linux/fs/nfsd/nfsfh.c (revision c537b994505099b7197e7d3125b942ecbcc51eb6) 
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 #include <asm/pgtable.h>
21 
22 #include <linux/sunrpc/clnt.h>
23 #include <linux/sunrpc/svc.h>
24 #include <linux/nfsd/nfsd.h>
25 
26 #define NFSDDBG_FACILITY		NFSDDBG_FH
27 
28 
29 static int nfsd_nr_verified;
30 static int nfsd_nr_put;
31 
32 extern struct export_operations export_op_default;
33 
34 #define	CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
35 
36 /*
37  * our acceptability function.
38  * if NOSUBTREECHECK, accept anything
39  * if not, require that we can walk up to exp->ex_dentry
40  * doing some checks on the 'x' bits
41  */
42 static int nfsd_acceptable(void *expv, struct dentry *dentry)
43 {
44 	struct svc_export *exp = expv;
45 	int rv;
46 	struct dentry *tdentry;
47 	struct dentry *parent;
48 
49 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
50 		return 1;
51 
52 	tdentry = dget(dentry);
53 	while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
54 		/* make sure parents give x permission to user */
55 		int err;
56 		parent = dget_parent(tdentry);
57 		err = permission(parent->d_inode, MAY_EXEC, NULL);
58 		if (err < 0) {
59 			dput(parent);
60 			break;
61 		}
62 		dput(tdentry);
63 		tdentry = parent;
64 	}
65 	if (tdentry != exp->ex_dentry)
66 		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
67 	rv = (tdentry == exp->ex_dentry);
68 	dput(tdentry);
69 	return rv;
70 }
71 
72 /* Type check. The correct error return for type mismatches does not seem to be
73  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
74  * comment in the NFSv3 spec says this is incorrect (implementation notes for
75  * the write call).
76  */
77 static inline __be32
78 nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
79 {
80 	/* Type can be negative when creating hardlinks - not to a dir */
81 	if (type > 0 && (mode & S_IFMT) != type) {
82 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
83 			return nfserr_symlink;
84 		else if (type == S_IFDIR)
85 			return nfserr_notdir;
86 		else if ((mode & S_IFMT) == S_IFDIR)
87 			return nfserr_isdir;
88 		else
89 			return nfserr_inval;
90 	}
91 	if (type < 0 && (mode & S_IFMT) == -type) {
92 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
93 			return nfserr_symlink;
94 		else if (type == -S_IFDIR)
95 			return nfserr_isdir;
96 		else
97 			return nfserr_notdir;
98 	}
99 	return 0;
100 }
101 
102 /*
103  * Perform sanity checks on the dentry in a client's file handle.
104  *
105  * Note that the file handle dentry may need to be freed even after
106  * an error return.
107  *
108  * This is only called at the start of an nfsproc call, so fhp points to
109  * a svc_fh which is all 0 except for the over-the-wire file handle.
110  */
111 __be32
112 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
113 {
114 	struct knfsd_fh	*fh = &fhp->fh_handle;
115 	struct svc_export *exp = NULL;
116 	struct dentry	*dentry;
117 	__be32		error = 0;
118 
119 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
120 
121 	if (!fhp->fh_dentry) {
122 		__u32 *datap=NULL;
123 		__u32 tfh[3];		/* filehandle fragment for oldstyle filehandles */
124 		int fileid_type;
125 		int data_left = fh->fh_size/4;
126 
127 		error = nfserr_stale;
128 		if (rqstp->rq_client == NULL)
129 			goto out;
130 		if (rqstp->rq_vers > 2)
131 			error = nfserr_badhandle;
132 		if (rqstp->rq_vers == 4 && fh->fh_size == 0)
133 			return nfserr_nofilehandle;
134 
135 		if (fh->fh_version == 1) {
136 			int len;
137 			datap = fh->fh_auth;
138 			if (--data_left<0) goto out;
139 			switch (fh->fh_auth_type) {
140 			case 0: break;
141 			default: goto out;
142 			}
143 			len = key_len(fh->fh_fsid_type) / 4;
144 			if (len == 0) goto out;
145 			if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
146 				/* deprecated, convert to type 3 */
147 				len = key_len(FSID_ENCODE_DEV)/4;
148 				fh->fh_fsid_type = FSID_ENCODE_DEV;
149 				fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
150 				fh->fh_fsid[1] = fh->fh_fsid[2];
151 			}
152 			if ((data_left -= len)<0) goto out;
153 			exp = exp_find(rqstp->rq_client, fh->fh_fsid_type, datap, &rqstp->rq_chandle);
154 			datap += len;
155 		} else {
156 			dev_t xdev;
157 			ino_t xino;
158 			if (fh->fh_size != NFS_FHSIZE)
159 				goto out;
160 			/* assume old filehandle format */
161 			xdev = old_decode_dev(fh->ofh_xdev);
162 			xino = u32_to_ino_t(fh->ofh_xino);
163 			mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
164 			exp = exp_find(rqstp->rq_client, FSID_DEV, tfh,
165 				       &rqstp->rq_chandle);
166 		}
167 
168 		if (IS_ERR(exp) && (PTR_ERR(exp) == -EAGAIN
169 				|| PTR_ERR(exp) == -ETIMEDOUT)) {
170 			error = nfserrno(PTR_ERR(exp));
171 			goto out;
172 		}
173 
174 		error = nfserr_stale;
175 		if (!exp || IS_ERR(exp))
176 			goto out;
177 
178 		/* Check if the request originated from a secure port. */
179 		error = nfserr_perm;
180 		if (!rqstp->rq_secure && EX_SECURE(exp)) {
181 			char buf[RPC_MAX_ADDRBUFLEN];
182 			printk(KERN_WARNING
183 			       "nfsd: request from insecure port %s!\n",
184 			       svc_print_addr(rqstp, buf, sizeof(buf)));
185 			goto out;
186 		}
187 
188 		/* Set user creds for this exportpoint */
189 		error = nfserrno(nfsd_setuser(rqstp, exp));
190 		if (error)
191 			goto out;
192 
193 		/*
194 		 * Look up the dentry using the NFS file handle.
195 		 */
196 		error = nfserr_stale;
197 		if (rqstp->rq_vers > 2)
198 			error = nfserr_badhandle;
199 
200 		if (fh->fh_version != 1) {
201 			tfh[0] = fh->ofh_ino;
202 			tfh[1] = fh->ofh_generation;
203 			tfh[2] = fh->ofh_dirino;
204 			datap = tfh;
205 			data_left = 3;
206 			if (fh->ofh_dirino == 0)
207 				fileid_type = 1;
208 			else
209 				fileid_type = 2;
210 		} else
211 			fileid_type = fh->fh_fileid_type;
212 
213 		if (fileid_type == 0)
214 			dentry = dget(exp->ex_dentry);
215 		else {
216 			struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
217 			dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
218 						     datap, data_left,
219 						     fileid_type,
220 						     nfsd_acceptable, exp);
221 		}
222 		if (dentry == NULL)
223 			goto out;
224 		if (IS_ERR(dentry)) {
225 			if (PTR_ERR(dentry) != -EINVAL)
226 				error = nfserrno(PTR_ERR(dentry));
227 			goto out;
228 		}
229 
230 		if (S_ISDIR(dentry->d_inode->i_mode) &&
231 		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
232 			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
233 			       dentry->d_parent->d_name.name, dentry->d_name.name);
234 		}
235 
236 		fhp->fh_dentry = dentry;
237 		fhp->fh_export = exp;
238 		nfsd_nr_verified++;
239 	} else {
240 		/* just rechecking permissions
241 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
242 		 */
243 		dprintk("nfsd: fh_verify - just checking\n");
244 		dentry = fhp->fh_dentry;
245 		exp = fhp->fh_export;
246 		/* Set user creds for this exportpoint; necessary even
247 		 * in the "just checking" case because this may be a
248 		 * filehandle that was created by fh_compose, and that
249 		 * is about to be used in another nfsv4 compound
250 		 * operation */
251 		error = nfserrno(nfsd_setuser(rqstp, exp));
252 		if (error)
253 			goto out;
254 	}
255 	cache_get(&exp->h);
256 
257 
258 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
259 	if (error)
260 		goto out;
261 
262 	/* Finally, check access permissions. */
263 	error = nfsd_permission(exp, dentry, access);
264 
265 	if (error) {
266 		dprintk("fh_verify: %s/%s permission failure, "
267 			"acc=%x, error=%d\n",
268 			dentry->d_parent->d_name.name,
269 			dentry->d_name.name,
270 			access, ntohl(error));
271 	}
272 out:
273 	if (exp && !IS_ERR(exp))
274 		exp_put(exp);
275 	if (error == nfserr_stale)
276 		nfsdstats.fh_stale++;
277 	return error;
278 }
279 
280 
281 /*
282  * Compose a file handle for an NFS reply.
283  *
284  * Note that when first composed, the dentry may not yet have
285  * an inode.  In this case a call to fh_update should be made
286  * before the fh goes out on the wire ...
287  */
288 static inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
289 			     __u32 *datap, int *maxsize)
290 {
291 	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
292 
293 	if (dentry == exp->ex_dentry) {
294 		*maxsize = 0;
295 		return 0;
296 	}
297 
298 	return CALL(nop,encode_fh)(dentry, datap, maxsize,
299 			  !(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
300 }
301 
302 /*
303  * for composing old style file handles
304  */
305 static inline void _fh_update_old(struct dentry *dentry,
306 				  struct svc_export *exp,
307 				  struct knfsd_fh *fh)
308 {
309 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
310 	fh->ofh_generation = dentry->d_inode->i_generation;
311 	if (S_ISDIR(dentry->d_inode->i_mode) ||
312 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
313 		fh->ofh_dirino = 0;
314 }
315 
316 __be32
317 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
318 	   struct svc_fh *ref_fh)
319 {
320 	/* ref_fh is a reference file handle.
321 	 * if it is non-null and for the same filesystem, then we should compose
322 	 * a filehandle which is of the same version, where possible.
323 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
324 	 * Then create a 32byte filehandle using nfs_fhbase_old
325 	 *
326 	 */
327 
328 	u8 version = 1;
329 	u8 fsid_type = 0;
330 	struct inode * inode = dentry->d_inode;
331 	struct dentry *parent = dentry->d_parent;
332 	__u32 *datap;
333 	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
334 	int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);
335 
336 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
337 		MAJOR(ex_dev), MINOR(ex_dev),
338 		(long) exp->ex_dentry->d_inode->i_ino,
339 		parent->d_name.name, dentry->d_name.name,
340 		(inode ? inode->i_ino : 0));
341 
342 	/* Choose filehandle version and fsid type based on
343 	 * the reference filehandle (if it is in the same export)
344 	 * or the export options.
345 	 */
346 	if (ref_fh && ref_fh->fh_export == exp) {
347 		version = ref_fh->fh_handle.fh_version;
348 		if (version == 0xca)
349 			fsid_type = FSID_DEV;
350 		else
351 			fsid_type = ref_fh->fh_handle.fh_fsid_type;
352 		/* We know this version/type works for this export
353 		 * so there is no need for further checks.
354 		 */
355 	} else if (exp->ex_uuid) {
356 		if (fhp->fh_maxsize >= 64) {
357 			if (root_export)
358 				fsid_type = FSID_UUID16;
359 			else
360 				fsid_type = FSID_UUID16_INUM;
361 		} else {
362 			if (root_export)
363 				fsid_type = FSID_UUID8;
364 			else
365 				fsid_type = FSID_UUID4_INUM;
366 		}
367 	} else if (exp->ex_flags & NFSEXP_FSID)
368 		fsid_type = FSID_NUM;
369 	else if (!old_valid_dev(ex_dev))
370 		/* for newer device numbers, we must use a newer fsid format */
371 		fsid_type = FSID_ENCODE_DEV;
372 	else
373 		fsid_type = FSID_DEV;
374 
375 	if (ref_fh == fhp)
376 		fh_put(ref_fh);
377 
378 	if (fhp->fh_locked || fhp->fh_dentry) {
379 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
380 		       parent->d_name.name, dentry->d_name.name);
381 	}
382 	if (fhp->fh_maxsize < NFS_FHSIZE)
383 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
384 		       fhp->fh_maxsize,
385 		       parent->d_name.name, dentry->d_name.name);
386 
387 	fhp->fh_dentry = dget(dentry); /* our internal copy */
388 	fhp->fh_export = exp;
389 	cache_get(&exp->h);
390 
391 	if (version == 0xca) {
392 		/* old style filehandle please */
393 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
394 		fhp->fh_handle.fh_size = NFS_FHSIZE;
395 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
396 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
397 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
398 		fhp->fh_handle.ofh_xino =
399 			ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
400 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
401 		if (inode)
402 			_fh_update_old(dentry, exp, &fhp->fh_handle);
403 	} else {
404 		int len;
405 		fhp->fh_handle.fh_version = 1;
406 		fhp->fh_handle.fh_auth_type = 0;
407 		datap = fhp->fh_handle.fh_auth+0;
408 		fhp->fh_handle.fh_fsid_type = fsid_type;
409 		mk_fsid(fsid_type, datap, ex_dev,
410 			exp->ex_dentry->d_inode->i_ino,
411 			exp->ex_fsid, exp->ex_uuid);
412 
413 		len = key_len(fsid_type);
414 		datap += len/4;
415 		fhp->fh_handle.fh_size = 4 + len;
416 
417 		if (inode) {
418 			int size = (fhp->fh_maxsize-len-4)/4;
419 			fhp->fh_handle.fh_fileid_type =
420 				_fh_update(dentry, exp, datap, &size);
421 			fhp->fh_handle.fh_size += size*4;
422 		}
423 		if (fhp->fh_handle.fh_fileid_type == 255)
424 			return nfserr_opnotsupp;
425 	}
426 
427 	nfsd_nr_verified++;
428 	return 0;
429 }
430 
431 /*
432  * Update file handle information after changing a dentry.
433  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
434  */
435 __be32
436 fh_update(struct svc_fh *fhp)
437 {
438 	struct dentry *dentry;
439 	__u32 *datap;
440 
441 	if (!fhp->fh_dentry)
442 		goto out_bad;
443 
444 	dentry = fhp->fh_dentry;
445 	if (!dentry->d_inode)
446 		goto out_negative;
447 	if (fhp->fh_handle.fh_version != 1) {
448 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
449 	} else {
450 		int size;
451 		if (fhp->fh_handle.fh_fileid_type != 0)
452 			goto out;
453 		datap = fhp->fh_handle.fh_auth+
454 			fhp->fh_handle.fh_size/4 -1;
455 		size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
456 		fhp->fh_handle.fh_fileid_type =
457 			_fh_update(dentry, fhp->fh_export, datap, &size);
458 		fhp->fh_handle.fh_size += size*4;
459 		if (fhp->fh_handle.fh_fileid_type == 255)
460 			return nfserr_opnotsupp;
461 	}
462 out:
463 	return 0;
464 
465 out_bad:
466 	printk(KERN_ERR "fh_update: fh not verified!\n");
467 	goto out;
468 out_negative:
469 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
470 		dentry->d_parent->d_name.name, dentry->d_name.name);
471 	goto out;
472 }
473 
474 /*
475  * Release a file handle.
476  */
477 void
478 fh_put(struct svc_fh *fhp)
479 {
480 	struct dentry * dentry = fhp->fh_dentry;
481 	struct svc_export * exp = fhp->fh_export;
482 	if (dentry) {
483 		fh_unlock(fhp);
484 		fhp->fh_dentry = NULL;
485 		dput(dentry);
486 #ifdef CONFIG_NFSD_V3
487 		fhp->fh_pre_saved = 0;
488 		fhp->fh_post_saved = 0;
489 #endif
490 		nfsd_nr_put++;
491 	}
492 	if (exp) {
493 		cache_put(&exp->h, &svc_export_cache);
494 		fhp->fh_export = NULL;
495 	}
496 	return;
497 }
498 
499 /*
500  * Shorthand for dprintk()'s
501  */
502 char * SVCFH_fmt(struct svc_fh *fhp)
503 {
504 	struct knfsd_fh *fh = &fhp->fh_handle;
505 
506 	static char buf[80];
507 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
508 		fh->fh_size,
509 		fh->fh_base.fh_pad[0],
510 		fh->fh_base.fh_pad[1],
511 		fh->fh_base.fh_pad[2],
512 		fh->fh_base.fh_pad[3],
513 		fh->fh_base.fh_pad[4],
514 		fh->fh_base.fh_pad[5]);
515 	return buf;
516 }
517 
518 enum fsid_source fsid_source(struct svc_fh *fhp)
519 {
520 	if (fhp->fh_handle.fh_version != 1)
521 		return FSIDSOURCE_DEV;
522 	switch(fhp->fh_handle.fh_fsid_type) {
523 	case FSID_DEV:
524 	case FSID_ENCODE_DEV:
525 	case FSID_MAJOR_MINOR:
526 		return FSIDSOURCE_DEV;
527 	case FSID_NUM:
528 		return FSIDSOURCE_FSID;
529 	default:
530 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
531 			return FSIDSOURCE_FSID;
532 		else
533 			return FSIDSOURCE_UUID;
534 	}
535 }
536