xref: /linux/fs/nfsd/nfsfh.c (revision 643d1f7fe3aa12c8bdea6fa5b4ba874ff6dd601d) 
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/sunrpc/svcauth_gss.h>
24 #include <linux/nfsd/nfsd.h>
25 #include "auth.h"
26 
27 #define NFSDDBG_FACILITY		NFSDDBG_FH
28 
29 
30 static int nfsd_nr_verified;
31 static int nfsd_nr_put;
32 
33 /*
34  * our acceptability function.
35  * if NOSUBTREECHECK, accept anything
36  * if not, require that we can walk up to exp->ex_dentry
37  * doing some checks on the 'x' bits
38  */
39 static int nfsd_acceptable(void *expv, struct dentry *dentry)
40 {
41 	struct svc_export *exp = expv;
42 	int rv;
43 	struct dentry *tdentry;
44 	struct dentry *parent;
45 
46 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
47 		return 1;
48 
49 	tdentry = dget(dentry);
50 	while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
51 		/* make sure parents give x permission to user */
52 		int err;
53 		parent = dget_parent(tdentry);
54 		err = permission(parent->d_inode, MAY_EXEC, NULL);
55 		if (err < 0) {
56 			dput(parent);
57 			break;
58 		}
59 		dput(tdentry);
60 		tdentry = parent;
61 	}
62 	if (tdentry != exp->ex_dentry)
63 		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
64 	rv = (tdentry == exp->ex_dentry);
65 	dput(tdentry);
66 	return rv;
67 }
68 
69 /* Type check. The correct error return for type mismatches does not seem to be
70  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
71  * comment in the NFSv3 spec says this is incorrect (implementation notes for
72  * the write call).
73  */
74 static inline __be32
75 nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
76 {
77 	/* Type can be negative when creating hardlinks - not to a dir */
78 	if (type > 0 && (mode & S_IFMT) != type) {
79 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
80 			return nfserr_symlink;
81 		else if (type == S_IFDIR)
82 			return nfserr_notdir;
83 		else if ((mode & S_IFMT) == S_IFDIR)
84 			return nfserr_isdir;
85 		else
86 			return nfserr_inval;
87 	}
88 	if (type < 0 && (mode & S_IFMT) == -type) {
89 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
90 			return nfserr_symlink;
91 		else if (type == -S_IFDIR)
92 			return nfserr_isdir;
93 		else
94 			return nfserr_notdir;
95 	}
96 	return 0;
97 }
98 
99 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
100 					  struct svc_export *exp)
101 {
102 	/* Check if the request originated from a secure port. */
103 	if (!rqstp->rq_secure && EX_SECURE(exp)) {
104 		char buf[RPC_MAX_ADDRBUFLEN];
105 		dprintk(KERN_WARNING
106 		       "nfsd: request from insecure port %s!\n",
107 		       svc_print_addr(rqstp, buf, sizeof(buf)));
108 		return nfserr_perm;
109 	}
110 
111 	/* Set user creds for this exportpoint */
112 	return nfserrno(nfsd_setuser(rqstp, exp));
113 }
114 
115 /*
116  * Perform sanity checks on the dentry in a client's file handle.
117  *
118  * Note that the file handle dentry may need to be freed even after
119  * an error return.
120  *
121  * This is only called at the start of an nfsproc call, so fhp points to
122  * a svc_fh which is all 0 except for the over-the-wire file handle.
123  */
124 __be32
125 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
126 {
127 	struct knfsd_fh	*fh = &fhp->fh_handle;
128 	struct svc_export *exp = NULL;
129 	struct dentry	*dentry;
130 	__be32		error = 0;
131 
132 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
133 
134 	if (!fhp->fh_dentry) {
135 		struct fid *fid = NULL, sfid;
136 		int fileid_type;
137 		int data_left = fh->fh_size/4;
138 
139 		error = nfserr_stale;
140 		if (rqstp->rq_vers > 2)
141 			error = nfserr_badhandle;
142 		if (rqstp->rq_vers == 4 && fh->fh_size == 0)
143 			return nfserr_nofilehandle;
144 
145 		if (fh->fh_version == 1) {
146 			int len;
147 			if (--data_left<0) goto out;
148 			switch (fh->fh_auth_type) {
149 			case 0: break;
150 			default: goto out;
151 			}
152 			len = key_len(fh->fh_fsid_type) / 4;
153 			if (len == 0) goto out;
154 			if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
155 				/* deprecated, convert to type 3 */
156 				len = key_len(FSID_ENCODE_DEV)/4;
157 				fh->fh_fsid_type = FSID_ENCODE_DEV;
158 				fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
159 				fh->fh_fsid[1] = fh->fh_fsid[2];
160 			}
161 			if ((data_left -= len)<0) goto out;
162 			exp = rqst_exp_find(rqstp, fh->fh_fsid_type,
163 					    fh->fh_auth);
164 			fid = (struct fid *)(fh->fh_auth + len);
165 		} else {
166 			__u32 tfh[2];
167 			dev_t xdev;
168 			ino_t xino;
169 			if (fh->fh_size != NFS_FHSIZE)
170 				goto out;
171 			/* assume old filehandle format */
172 			xdev = old_decode_dev(fh->ofh_xdev);
173 			xino = u32_to_ino_t(fh->ofh_xino);
174 			mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
175 			exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
176 		}
177 
178 		error = nfserr_stale;
179 		if (PTR_ERR(exp) == -ENOENT)
180 			goto out;
181 
182 		if (IS_ERR(exp)) {
183 			error = nfserrno(PTR_ERR(exp));
184 			goto out;
185 		}
186 
187 		error = nfsd_setuser_and_check_port(rqstp, exp);
188 		if (error)
189 			goto out;
190 
191 		/*
192 		 * Look up the dentry using the NFS file handle.
193 		 */
194 		error = nfserr_stale;
195 		if (rqstp->rq_vers > 2)
196 			error = nfserr_badhandle;
197 
198 		if (fh->fh_version != 1) {
199 			sfid.i32.ino = fh->ofh_ino;
200 			sfid.i32.gen = fh->ofh_generation;
201 			sfid.i32.parent_ino = fh->ofh_dirino;
202 			fid = &sfid;
203 			data_left = 3;
204 			if (fh->ofh_dirino == 0)
205 				fileid_type = FILEID_INO32_GEN;
206 			else
207 				fileid_type = FILEID_INO32_GEN_PARENT;
208 		} else
209 			fileid_type = fh->fh_fileid_type;
210 
211 		if (fileid_type == FILEID_ROOT)
212 			dentry = dget(exp->ex_dentry);
213 		else {
214 			dentry = exportfs_decode_fh(exp->ex_mnt, fid,
215 					data_left, fileid_type,
216 					nfsd_acceptable, exp);
217 		}
218 		if (dentry == NULL)
219 			goto out;
220 		if (IS_ERR(dentry)) {
221 			if (PTR_ERR(dentry) != -EINVAL)
222 				error = nfserrno(PTR_ERR(dentry));
223 			goto out;
224 		}
225 
226 		if (S_ISDIR(dentry->d_inode->i_mode) &&
227 		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
228 			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
229 			       dentry->d_parent->d_name.name, dentry->d_name.name);
230 		}
231 
232 		fhp->fh_dentry = dentry;
233 		fhp->fh_export = exp;
234 		nfsd_nr_verified++;
235 	} else {
236 		/*
237 		 * just rechecking permissions
238 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create
239 		 * does as well)
240 		 */
241 		dprintk("nfsd: fh_verify - just checking\n");
242 		dentry = fhp->fh_dentry;
243 		exp = fhp->fh_export;
244 		/*
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 		 */
251 		error = nfsd_setuser_and_check_port(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 	if (!(access & MAY_LOCK)) {
263 		/*
264 		 * pseudoflavor restrictions are not enforced on NLM,
265 		 * which clients virtually always use auth_sys for,
266 		 * even while using RPCSEC_GSS for NFS.
267 		 */
268 		error = check_nfsd_access(exp, rqstp);
269 		if (error)
270 			goto out;
271 	}
272 
273 	/* Finally, check access permissions. */
274 	error = nfsd_permission(rqstp, exp, dentry, access);
275 
276 	if (error) {
277 		dprintk("fh_verify: %s/%s permission failure, "
278 			"acc=%x, error=%d\n",
279 			dentry->d_parent->d_name.name,
280 			dentry->d_name.name,
281 			access, ntohl(error));
282 	}
283 out:
284 	if (exp && !IS_ERR(exp))
285 		exp_put(exp);
286 	if (error == nfserr_stale)
287 		nfsdstats.fh_stale++;
288 	return error;
289 }
290 
291 
292 /*
293  * Compose a file handle for an NFS reply.
294  *
295  * Note that when first composed, the dentry may not yet have
296  * an inode.  In this case a call to fh_update should be made
297  * before the fh goes out on the wire ...
298  */
299 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
300 		struct dentry *dentry)
301 {
302 	if (dentry != exp->ex_dentry) {
303 		struct fid *fid = (struct fid *)
304 			(fhp->fh_handle.fh_auth + fhp->fh_handle.fh_size/4 - 1);
305 		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
306 		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
307 
308 		fhp->fh_handle.fh_fileid_type =
309 			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
310 		fhp->fh_handle.fh_size += maxsize * 4;
311 	} else {
312 		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
313 	}
314 }
315 
316 /*
317  * for composing old style file handles
318  */
319 static inline void _fh_update_old(struct dentry *dentry,
320 				  struct svc_export *exp,
321 				  struct knfsd_fh *fh)
322 {
323 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
324 	fh->ofh_generation = dentry->d_inode->i_generation;
325 	if (S_ISDIR(dentry->d_inode->i_mode) ||
326 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
327 		fh->ofh_dirino = 0;
328 }
329 
330 __be32
331 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
332 	   struct svc_fh *ref_fh)
333 {
334 	/* ref_fh is a reference file handle.
335 	 * if it is non-null and for the same filesystem, then we should compose
336 	 * a filehandle which is of the same version, where possible.
337 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
338 	 * Then create a 32byte filehandle using nfs_fhbase_old
339 	 *
340 	 */
341 
342 	u8 version;
343 	u8 fsid_type = 0;
344 	struct inode * inode = dentry->d_inode;
345 	struct dentry *parent = dentry->d_parent;
346 	__u32 *datap;
347 	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
348 	int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);
349 
350 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
351 		MAJOR(ex_dev), MINOR(ex_dev),
352 		(long) exp->ex_dentry->d_inode->i_ino,
353 		parent->d_name.name, dentry->d_name.name,
354 		(inode ? inode->i_ino : 0));
355 
356 	/* Choose filehandle version and fsid type based on
357 	 * the reference filehandle (if it is in the same export)
358 	 * or the export options.
359 	 */
360  retry:
361 	version = 1;
362 	if (ref_fh && ref_fh->fh_export == exp) {
363 		version = ref_fh->fh_handle.fh_version;
364 		fsid_type = ref_fh->fh_handle.fh_fsid_type;
365 
366 		if (ref_fh == fhp)
367 			fh_put(ref_fh);
368 		ref_fh = NULL;
369 
370 		switch (version) {
371 		case 0xca:
372 			fsid_type = FSID_DEV;
373 			break;
374 		case 1:
375 			break;
376 		default:
377 			goto retry;
378 		}
379 
380 		/* Need to check that this type works for this
381 		 * export point.  As the fsid -> filesystem mapping
382 		 * was guided by user-space, there is no guarantee
383 		 * that the filesystem actually supports that fsid
384 		 * type. If it doesn't we loop around again without
385 		 * ref_fh set.
386 		 */
387 		switch(fsid_type) {
388 		case FSID_DEV:
389 			if (!old_valid_dev(ex_dev))
390 				goto retry;
391 			/* FALL THROUGH */
392 		case FSID_MAJOR_MINOR:
393 		case FSID_ENCODE_DEV:
394 			if (!(exp->ex_dentry->d_inode->i_sb->s_type->fs_flags
395 			      & FS_REQUIRES_DEV))
396 				goto retry;
397 			break;
398 		case FSID_NUM:
399 			if (! (exp->ex_flags & NFSEXP_FSID))
400 				goto retry;
401 			break;
402 		case FSID_UUID8:
403 		case FSID_UUID16:
404 			if (!root_export)
405 				goto retry;
406 			/* fall through */
407 		case FSID_UUID4_INUM:
408 		case FSID_UUID16_INUM:
409 			if (exp->ex_uuid == NULL)
410 				goto retry;
411 			break;
412 		}
413 	} else if (exp->ex_uuid) {
414 		if (fhp->fh_maxsize >= 64) {
415 			if (root_export)
416 				fsid_type = FSID_UUID16;
417 			else
418 				fsid_type = FSID_UUID16_INUM;
419 		} else {
420 			if (root_export)
421 				fsid_type = FSID_UUID8;
422 			else
423 				fsid_type = FSID_UUID4_INUM;
424 		}
425 	} else if (exp->ex_flags & NFSEXP_FSID)
426 		fsid_type = FSID_NUM;
427 	else if (!old_valid_dev(ex_dev))
428 		/* for newer device numbers, we must use a newer fsid format */
429 		fsid_type = FSID_ENCODE_DEV;
430 	else
431 		fsid_type = FSID_DEV;
432 
433 	if (ref_fh == fhp)
434 		fh_put(ref_fh);
435 
436 	if (fhp->fh_locked || fhp->fh_dentry) {
437 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
438 		       parent->d_name.name, dentry->d_name.name);
439 	}
440 	if (fhp->fh_maxsize < NFS_FHSIZE)
441 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
442 		       fhp->fh_maxsize,
443 		       parent->d_name.name, dentry->d_name.name);
444 
445 	fhp->fh_dentry = dget(dentry); /* our internal copy */
446 	fhp->fh_export = exp;
447 	cache_get(&exp->h);
448 
449 	if (version == 0xca) {
450 		/* old style filehandle please */
451 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
452 		fhp->fh_handle.fh_size = NFS_FHSIZE;
453 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
454 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
455 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
456 		fhp->fh_handle.ofh_xino =
457 			ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
458 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
459 		if (inode)
460 			_fh_update_old(dentry, exp, &fhp->fh_handle);
461 	} else {
462 		int len;
463 		fhp->fh_handle.fh_version = 1;
464 		fhp->fh_handle.fh_auth_type = 0;
465 		datap = fhp->fh_handle.fh_auth+0;
466 		fhp->fh_handle.fh_fsid_type = fsid_type;
467 		mk_fsid(fsid_type, datap, ex_dev,
468 			exp->ex_dentry->d_inode->i_ino,
469 			exp->ex_fsid, exp->ex_uuid);
470 
471 		len = key_len(fsid_type);
472 		datap += len/4;
473 		fhp->fh_handle.fh_size = 4 + len;
474 
475 		if (inode)
476 			_fh_update(fhp, exp, dentry);
477 		if (fhp->fh_handle.fh_fileid_type == 255)
478 			return nfserr_opnotsupp;
479 	}
480 
481 	nfsd_nr_verified++;
482 	return 0;
483 }
484 
485 /*
486  * Update file handle information after changing a dentry.
487  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
488  */
489 __be32
490 fh_update(struct svc_fh *fhp)
491 {
492 	struct dentry *dentry;
493 
494 	if (!fhp->fh_dentry)
495 		goto out_bad;
496 
497 	dentry = fhp->fh_dentry;
498 	if (!dentry->d_inode)
499 		goto out_negative;
500 	if (fhp->fh_handle.fh_version != 1) {
501 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
502 	} else {
503 		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
504 			goto out;
505 
506 		_fh_update(fhp, fhp->fh_export, dentry);
507 		if (fhp->fh_handle.fh_fileid_type == 255)
508 			return nfserr_opnotsupp;
509 	}
510 out:
511 	return 0;
512 
513 out_bad:
514 	printk(KERN_ERR "fh_update: fh not verified!\n");
515 	goto out;
516 out_negative:
517 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
518 		dentry->d_parent->d_name.name, dentry->d_name.name);
519 	goto out;
520 }
521 
522 /*
523  * Release a file handle.
524  */
525 void
526 fh_put(struct svc_fh *fhp)
527 {
528 	struct dentry * dentry = fhp->fh_dentry;
529 	struct svc_export * exp = fhp->fh_export;
530 	if (dentry) {
531 		fh_unlock(fhp);
532 		fhp->fh_dentry = NULL;
533 		dput(dentry);
534 #ifdef CONFIG_NFSD_V3
535 		fhp->fh_pre_saved = 0;
536 		fhp->fh_post_saved = 0;
537 #endif
538 		nfsd_nr_put++;
539 	}
540 	if (exp) {
541 		cache_put(&exp->h, &svc_export_cache);
542 		fhp->fh_export = NULL;
543 	}
544 	return;
545 }
546 
547 /*
548  * Shorthand for dprintk()'s
549  */
550 char * SVCFH_fmt(struct svc_fh *fhp)
551 {
552 	struct knfsd_fh *fh = &fhp->fh_handle;
553 
554 	static char buf[80];
555 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
556 		fh->fh_size,
557 		fh->fh_base.fh_pad[0],
558 		fh->fh_base.fh_pad[1],
559 		fh->fh_base.fh_pad[2],
560 		fh->fh_base.fh_pad[3],
561 		fh->fh_base.fh_pad[4],
562 		fh->fh_base.fh_pad[5]);
563 	return buf;
564 }
565 
566 enum fsid_source fsid_source(struct svc_fh *fhp)
567 {
568 	if (fhp->fh_handle.fh_version != 1)
569 		return FSIDSOURCE_DEV;
570 	switch(fhp->fh_handle.fh_fsid_type) {
571 	case FSID_DEV:
572 	case FSID_ENCODE_DEV:
573 	case FSID_MAJOR_MINOR:
574 		if (fhp->fh_export->ex_dentry->d_inode->i_sb->s_type->fs_flags
575 		    & FS_REQUIRES_DEV)
576 			return FSIDSOURCE_DEV;
577 		break;
578 	case FSID_NUM:
579 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
580 			return FSIDSOURCE_FSID;
581 		break;
582 	default:
583 		break;
584 	}
585 	/* either a UUID type filehandle, or the filehandle doesn't
586 	 * match the export.
587 	 */
588 	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
589 		return FSIDSOURCE_FSID;
590 	if (fhp->fh_export->ex_uuid)
591 		return FSIDSOURCE_UUID;
592 	return FSIDSOURCE_DEV;
593 }
594