xref: /openbmc/linux/fs/nfsd/nfsfh.c (revision 3ab4d8b1215d61736e2a9a26bea7cc2e6b029e3d) 
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/fs.h>
14 #include <linux/unistd.h>
15 #include <linux/string.h>
16 #include <linux/stat.h>
17 #include <linux/dcache.h>
18 #include <linux/exportfs.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 /*
32  * our acceptability function.
33  * if NOSUBTREECHECK, accept anything
34  * if not, require that we can walk up to exp->ex_dentry
35  * doing some checks on the 'x' bits
36  */
37 static int nfsd_acceptable(void *expv, struct dentry *dentry)
38 {
39 	struct svc_export *exp = expv;
40 	int rv;
41 	struct dentry *tdentry;
42 	struct dentry *parent;
43 
44 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
45 		return 1;
46 
47 	tdentry = dget(dentry);
48 	while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
49 		/* make sure parents give x permission to user */
50 		int err;
51 		parent = dget_parent(tdentry);
52 		err = permission(parent->d_inode, MAY_EXEC, NULL);
53 		if (err < 0) {
54 			dput(parent);
55 			break;
56 		}
57 		dput(tdentry);
58 		tdentry = parent;
59 	}
60 	if (tdentry != exp->ex_dentry)
61 		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
62 	rv = (tdentry == exp->ex_dentry);
63 	dput(tdentry);
64 	return rv;
65 }
66 
67 /* Type check. The correct error return for type mismatches does not seem to be
68  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
69  * comment in the NFSv3 spec says this is incorrect (implementation notes for
70  * the write call).
71  */
72 static inline __be32
73 nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
74 {
75 	/* Type can be negative when creating hardlinks - not to a dir */
76 	if (type > 0 && (mode & S_IFMT) != type) {
77 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
78 			return nfserr_symlink;
79 		else if (type == S_IFDIR)
80 			return nfserr_notdir;
81 		else if ((mode & S_IFMT) == S_IFDIR)
82 			return nfserr_isdir;
83 		else
84 			return nfserr_inval;
85 	}
86 	if (type < 0 && (mode & S_IFMT) == -type) {
87 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
88 			return nfserr_symlink;
89 		else if (type == -S_IFDIR)
90 			return nfserr_isdir;
91 		else
92 			return nfserr_notdir;
93 	}
94 	return 0;
95 }
96 
97 /*
98  * Perform sanity checks on the dentry in a client's file handle.
99  *
100  * Note that the file handle dentry may need to be freed even after
101  * an error return.
102  *
103  * This is only called at the start of an nfsproc call, so fhp points to
104  * a svc_fh which is all 0 except for the over-the-wire file handle.
105  */
106 __be32
107 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
108 {
109 	struct knfsd_fh	*fh = &fhp->fh_handle;
110 	struct svc_export *exp = NULL;
111 	struct dentry	*dentry;
112 	__be32		error = 0;
113 
114 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
115 
116 	if (!fhp->fh_dentry) {
117 		__u32 *datap=NULL;
118 		__u32 tfh[3];		/* filehandle fragment for oldstyle filehandles */
119 		int fileid_type;
120 		int data_left = fh->fh_size/4;
121 
122 		error = nfserr_stale;
123 		if (rqstp->rq_vers > 2)
124 			error = nfserr_badhandle;
125 		if (rqstp->rq_vers == 4 && fh->fh_size == 0)
126 			return nfserr_nofilehandle;
127 
128 		if (fh->fh_version == 1) {
129 			int len;
130 			datap = fh->fh_auth;
131 			if (--data_left<0) goto out;
132 			switch (fh->fh_auth_type) {
133 			case 0: break;
134 			default: goto out;
135 			}
136 			len = key_len(fh->fh_fsid_type) / 4;
137 			if (len == 0) goto out;
138 			if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
139 				/* deprecated, convert to type 3 */
140 				len = key_len(FSID_ENCODE_DEV)/4;
141 				fh->fh_fsid_type = FSID_ENCODE_DEV;
142 				fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
143 				fh->fh_fsid[1] = fh->fh_fsid[2];
144 			}
145 			if ((data_left -= len)<0) goto out;
146 			exp = rqst_exp_find(rqstp, fh->fh_fsid_type, datap);
147 			datap += len;
148 		} else {
149 			dev_t xdev;
150 			ino_t xino;
151 			if (fh->fh_size != NFS_FHSIZE)
152 				goto out;
153 			/* assume old filehandle format */
154 			xdev = old_decode_dev(fh->ofh_xdev);
155 			xino = u32_to_ino_t(fh->ofh_xino);
156 			mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
157 			exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
158 		}
159 
160 		error = nfserr_stale;
161 		if (PTR_ERR(exp) == -ENOENT)
162 			goto out;
163 
164 		if (IS_ERR(exp)) {
165 			error = nfserrno(PTR_ERR(exp));
166 			goto out;
167 		}
168 
169 		/* Check if the request originated from a secure port. */
170 		error = nfserr_perm;
171 		if (!rqstp->rq_secure && EX_SECURE(exp)) {
172 			char buf[RPC_MAX_ADDRBUFLEN];
173 			printk(KERN_WARNING
174 			       "nfsd: request from insecure port %s!\n",
175 			       svc_print_addr(rqstp, buf, sizeof(buf)));
176 			goto out;
177 		}
178 
179 		/* Set user creds for this exportpoint */
180 		error = nfserrno(nfsd_setuser(rqstp, exp));
181 		if (error)
182 			goto out;
183 
184 		/*
185 		 * Look up the dentry using the NFS file handle.
186 		 */
187 		error = nfserr_stale;
188 		if (rqstp->rq_vers > 2)
189 			error = nfserr_badhandle;
190 
191 		if (fh->fh_version != 1) {
192 			tfh[0] = fh->ofh_ino;
193 			tfh[1] = fh->ofh_generation;
194 			tfh[2] = fh->ofh_dirino;
195 			datap = tfh;
196 			data_left = 3;
197 			if (fh->ofh_dirino == 0)
198 				fileid_type = 1;
199 			else
200 				fileid_type = 2;
201 		} else
202 			fileid_type = fh->fh_fileid_type;
203 
204 		if (fileid_type == 0)
205 			dentry = dget(exp->ex_dentry);
206 		else {
207 			dentry = exportfs_decode_fh(exp->ex_mnt, datap,
208 					data_left, fileid_type,
209 					nfsd_acceptable, exp);
210 		}
211 		if (dentry == NULL)
212 			goto out;
213 		if (IS_ERR(dentry)) {
214 			if (PTR_ERR(dentry) != -EINVAL)
215 				error = nfserrno(PTR_ERR(dentry));
216 			goto out;
217 		}
218 
219 		if (S_ISDIR(dentry->d_inode->i_mode) &&
220 		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
221 			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
222 			       dentry->d_parent->d_name.name, dentry->d_name.name);
223 		}
224 
225 		fhp->fh_dentry = dentry;
226 		fhp->fh_export = exp;
227 		nfsd_nr_verified++;
228 	} else {
229 		/* just rechecking permissions
230 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
231 		 */
232 		dprintk("nfsd: fh_verify - just checking\n");
233 		dentry = fhp->fh_dentry;
234 		exp = fhp->fh_export;
235 		/* Set user creds for this exportpoint; necessary even
236 		 * in the "just checking" case because this may be a
237 		 * filehandle that was created by fh_compose, and that
238 		 * is about to be used in another nfsv4 compound
239 		 * operation */
240 		error = nfserrno(nfsd_setuser(rqstp, exp));
241 		if (error)
242 			goto out;
243 	}
244 	cache_get(&exp->h);
245 
246 
247 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
248 	if (error)
249 		goto out;
250 
251 	/* Finally, check access permissions. */
252 	error = nfsd_permission(exp, dentry, access);
253 
254 	if (error) {
255 		dprintk("fh_verify: %s/%s permission failure, "
256 			"acc=%x, error=%d\n",
257 			dentry->d_parent->d_name.name,
258 			dentry->d_name.name,
259 			access, ntohl(error));
260 	}
261 out:
262 	if (exp && !IS_ERR(exp))
263 		exp_put(exp);
264 	if (error == nfserr_stale)
265 		nfsdstats.fh_stale++;
266 	return error;
267 }
268 
269 
270 /*
271  * Compose a file handle for an NFS reply.
272  *
273  * Note that when first composed, the dentry may not yet have
274  * an inode.  In this case a call to fh_update should be made
275  * before the fh goes out on the wire ...
276  */
277 static inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
278 			     __u32 *datap, int *maxsize)
279 {
280 	if (dentry == exp->ex_dentry) {
281 		*maxsize = 0;
282 		return 0;
283 	}
284 
285 	return exportfs_encode_fh(dentry, datap, maxsize,
286 			  !(exp->ex_flags & NFSEXP_NOSUBTREECHECK));
287 }
288 
289 /*
290  * for composing old style file handles
291  */
292 static inline void _fh_update_old(struct dentry *dentry,
293 				  struct svc_export *exp,
294 				  struct knfsd_fh *fh)
295 {
296 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
297 	fh->ofh_generation = dentry->d_inode->i_generation;
298 	if (S_ISDIR(dentry->d_inode->i_mode) ||
299 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
300 		fh->ofh_dirino = 0;
301 }
302 
303 __be32
304 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
305 	   struct svc_fh *ref_fh)
306 {
307 	/* ref_fh is a reference file handle.
308 	 * if it is non-null and for the same filesystem, then we should compose
309 	 * a filehandle which is of the same version, where possible.
310 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
311 	 * Then create a 32byte filehandle using nfs_fhbase_old
312 	 *
313 	 */
314 
315 	u8 version;
316 	u8 fsid_type = 0;
317 	struct inode * inode = dentry->d_inode;
318 	struct dentry *parent = dentry->d_parent;
319 	__u32 *datap;
320 	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
321 	int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);
322 
323 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
324 		MAJOR(ex_dev), MINOR(ex_dev),
325 		(long) exp->ex_dentry->d_inode->i_ino,
326 		parent->d_name.name, dentry->d_name.name,
327 		(inode ? inode->i_ino : 0));
328 
329 	/* Choose filehandle version and fsid type based on
330 	 * the reference filehandle (if it is in the same export)
331 	 * or the export options.
332 	 */
333  retry:
334 	version = 1;
335 	if (ref_fh && ref_fh->fh_export == exp) {
336 		version = ref_fh->fh_handle.fh_version;
337 		fsid_type = ref_fh->fh_handle.fh_fsid_type;
338 
339 		if (ref_fh == fhp)
340 			fh_put(ref_fh);
341 		ref_fh = NULL;
342 
343 		switch (version) {
344 		case 0xca:
345 			fsid_type = FSID_DEV;
346 			break;
347 		case 1:
348 			break;
349 		default:
350 			goto retry;
351 		}
352 
353 		/* Need to check that this type works for this
354 		 * export point.  As the fsid -> filesystem mapping
355 		 * was guided by user-space, there is no guarantee
356 		 * that the filesystem actually supports that fsid
357 		 * type. If it doesn't we loop around again without
358 		 * ref_fh set.
359 		 */
360 		switch(fsid_type) {
361 		case FSID_DEV:
362 			if (!old_valid_dev(ex_dev))
363 				goto retry;
364 			/* FALL THROUGH */
365 		case FSID_MAJOR_MINOR:
366 		case FSID_ENCODE_DEV:
367 			if (!(exp->ex_dentry->d_inode->i_sb->s_type->fs_flags
368 			      & FS_REQUIRES_DEV))
369 				goto retry;
370 			break;
371 		case FSID_NUM:
372 			if (! (exp->ex_flags & NFSEXP_FSID))
373 				goto retry;
374 			break;
375 		case FSID_UUID8:
376 		case FSID_UUID16:
377 			if (!root_export)
378 				goto retry;
379 			/* fall through */
380 		case FSID_UUID4_INUM:
381 		case FSID_UUID16_INUM:
382 			if (exp->ex_uuid == NULL)
383 				goto retry;
384 			break;
385 		}
386 	} else if (exp->ex_uuid) {
387 		if (fhp->fh_maxsize >= 64) {
388 			if (root_export)
389 				fsid_type = FSID_UUID16;
390 			else
391 				fsid_type = FSID_UUID16_INUM;
392 		} else {
393 			if (root_export)
394 				fsid_type = FSID_UUID8;
395 			else
396 				fsid_type = FSID_UUID4_INUM;
397 		}
398 	} else if (exp->ex_flags & NFSEXP_FSID)
399 		fsid_type = FSID_NUM;
400 	else if (!old_valid_dev(ex_dev))
401 		/* for newer device numbers, we must use a newer fsid format */
402 		fsid_type = FSID_ENCODE_DEV;
403 	else
404 		fsid_type = FSID_DEV;
405 
406 	if (ref_fh == fhp)
407 		fh_put(ref_fh);
408 
409 	if (fhp->fh_locked || fhp->fh_dentry) {
410 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
411 		       parent->d_name.name, dentry->d_name.name);
412 	}
413 	if (fhp->fh_maxsize < NFS_FHSIZE)
414 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
415 		       fhp->fh_maxsize,
416 		       parent->d_name.name, dentry->d_name.name);
417 
418 	fhp->fh_dentry = dget(dentry); /* our internal copy */
419 	fhp->fh_export = exp;
420 	cache_get(&exp->h);
421 
422 	if (version == 0xca) {
423 		/* old style filehandle please */
424 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
425 		fhp->fh_handle.fh_size = NFS_FHSIZE;
426 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
427 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
428 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
429 		fhp->fh_handle.ofh_xino =
430 			ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
431 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
432 		if (inode)
433 			_fh_update_old(dentry, exp, &fhp->fh_handle);
434 	} else {
435 		int len;
436 		fhp->fh_handle.fh_version = 1;
437 		fhp->fh_handle.fh_auth_type = 0;
438 		datap = fhp->fh_handle.fh_auth+0;
439 		fhp->fh_handle.fh_fsid_type = fsid_type;
440 		mk_fsid(fsid_type, datap, ex_dev,
441 			exp->ex_dentry->d_inode->i_ino,
442 			exp->ex_fsid, exp->ex_uuid);
443 
444 		len = key_len(fsid_type);
445 		datap += len/4;
446 		fhp->fh_handle.fh_size = 4 + len;
447 
448 		if (inode) {
449 			int size = (fhp->fh_maxsize-len-4)/4;
450 			fhp->fh_handle.fh_fileid_type =
451 				_fh_update(dentry, exp, datap, &size);
452 			fhp->fh_handle.fh_size += size*4;
453 		}
454 		if (fhp->fh_handle.fh_fileid_type == 255)
455 			return nfserr_opnotsupp;
456 	}
457 
458 	nfsd_nr_verified++;
459 	return 0;
460 }
461 
462 /*
463  * Update file handle information after changing a dentry.
464  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
465  */
466 __be32
467 fh_update(struct svc_fh *fhp)
468 {
469 	struct dentry *dentry;
470 	__u32 *datap;
471 
472 	if (!fhp->fh_dentry)
473 		goto out_bad;
474 
475 	dentry = fhp->fh_dentry;
476 	if (!dentry->d_inode)
477 		goto out_negative;
478 	if (fhp->fh_handle.fh_version != 1) {
479 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
480 	} else {
481 		int size;
482 		if (fhp->fh_handle.fh_fileid_type != 0)
483 			goto out;
484 		datap = fhp->fh_handle.fh_auth+
485 			fhp->fh_handle.fh_size/4 -1;
486 		size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
487 		fhp->fh_handle.fh_fileid_type =
488 			_fh_update(dentry, fhp->fh_export, datap, &size);
489 		fhp->fh_handle.fh_size += size*4;
490 		if (fhp->fh_handle.fh_fileid_type == 255)
491 			return nfserr_opnotsupp;
492 	}
493 out:
494 	return 0;
495 
496 out_bad:
497 	printk(KERN_ERR "fh_update: fh not verified!\n");
498 	goto out;
499 out_negative:
500 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
501 		dentry->d_parent->d_name.name, dentry->d_name.name);
502 	goto out;
503 }
504 
505 /*
506  * Release a file handle.
507  */
508 void
509 fh_put(struct svc_fh *fhp)
510 {
511 	struct dentry * dentry = fhp->fh_dentry;
512 	struct svc_export * exp = fhp->fh_export;
513 	if (dentry) {
514 		fh_unlock(fhp);
515 		fhp->fh_dentry = NULL;
516 		dput(dentry);
517 #ifdef CONFIG_NFSD_V3
518 		fhp->fh_pre_saved = 0;
519 		fhp->fh_post_saved = 0;
520 #endif
521 		nfsd_nr_put++;
522 	}
523 	if (exp) {
524 		cache_put(&exp->h, &svc_export_cache);
525 		fhp->fh_export = NULL;
526 	}
527 	return;
528 }
529 
530 /*
531  * Shorthand for dprintk()'s
532  */
533 char * SVCFH_fmt(struct svc_fh *fhp)
534 {
535 	struct knfsd_fh *fh = &fhp->fh_handle;
536 
537 	static char buf[80];
538 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
539 		fh->fh_size,
540 		fh->fh_base.fh_pad[0],
541 		fh->fh_base.fh_pad[1],
542 		fh->fh_base.fh_pad[2],
543 		fh->fh_base.fh_pad[3],
544 		fh->fh_base.fh_pad[4],
545 		fh->fh_base.fh_pad[5]);
546 	return buf;
547 }
548 
549 enum fsid_source fsid_source(struct svc_fh *fhp)
550 {
551 	if (fhp->fh_handle.fh_version != 1)
552 		return FSIDSOURCE_DEV;
553 	switch(fhp->fh_handle.fh_fsid_type) {
554 	case FSID_DEV:
555 	case FSID_ENCODE_DEV:
556 	case FSID_MAJOR_MINOR:
557 		return FSIDSOURCE_DEV;
558 	case FSID_NUM:
559 		return FSIDSOURCE_FSID;
560 	default:
561 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
562 			return FSIDSOURCE_FSID;
563 		else
564 			return FSIDSOURCE_UUID;
565 	}
566 }
567