xref: /openbmc/linux/fs/nfsd/nfsfh.c (revision 22246614)
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_path.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_path.dentry)
63 		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
64 	rv = (tdentry == exp->ex_path.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 		RPC_IFDEBUG(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  * Use the given filehandle to look up the corresponding export and
117  * dentry.  On success, the results are used to set fh_export and
118  * fh_dentry.
119  */
120 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
121 {
122 	struct knfsd_fh	*fh = &fhp->fh_handle;
123 	struct fid *fid = NULL, sfid;
124 	struct svc_export *exp;
125 	struct dentry *dentry;
126 	int fileid_type;
127 	int data_left = fh->fh_size/4;
128 	__be32 error;
129 
130 	error = nfserr_stale;
131 	if (rqstp->rq_vers > 2)
132 		error = nfserr_badhandle;
133 	if (rqstp->rq_vers == 4 && fh->fh_size == 0)
134 		return nfserr_nofilehandle;
135 
136 	if (fh->fh_version == 1) {
137 		int len;
138 
139 		if (--data_left < 0)
140 			return error;
141 		if (fh->fh_auth_type != 0)
142 			return error;
143 		len = key_len(fh->fh_fsid_type) / 4;
144 		if (len == 0)
145 			return error;
146 		if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
147 			/* deprecated, convert to type 3 */
148 			len = key_len(FSID_ENCODE_DEV)/4;
149 			fh->fh_fsid_type = FSID_ENCODE_DEV;
150 			fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
151 			fh->fh_fsid[1] = fh->fh_fsid[2];
152 		}
153 		data_left -= len;
154 		if (data_left < 0)
155 			return error;
156 		exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_auth);
157 		fid = (struct fid *)(fh->fh_auth + len);
158 	} else {
159 		__u32 tfh[2];
160 		dev_t xdev;
161 		ino_t xino;
162 
163 		if (fh->fh_size != NFS_FHSIZE)
164 			return error;
165 		/* assume old filehandle format */
166 		xdev = old_decode_dev(fh->ofh_xdev);
167 		xino = u32_to_ino_t(fh->ofh_xino);
168 		mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
169 		exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
170 	}
171 
172 	error = nfserr_stale;
173 	if (PTR_ERR(exp) == -ENOENT)
174 		return error;
175 
176 	if (IS_ERR(exp))
177 		return nfserrno(PTR_ERR(exp));
178 
179 	error = nfsd_setuser_and_check_port(rqstp, exp);
180 	if (error)
181 		goto out;
182 
183 	/*
184 	 * Look up the dentry using the NFS file handle.
185 	 */
186 	error = nfserr_stale;
187 	if (rqstp->rq_vers > 2)
188 		error = nfserr_badhandle;
189 
190 	if (fh->fh_version != 1) {
191 		sfid.i32.ino = fh->ofh_ino;
192 		sfid.i32.gen = fh->ofh_generation;
193 		sfid.i32.parent_ino = fh->ofh_dirino;
194 		fid = &sfid;
195 		data_left = 3;
196 		if (fh->ofh_dirino == 0)
197 			fileid_type = FILEID_INO32_GEN;
198 		else
199 			fileid_type = FILEID_INO32_GEN_PARENT;
200 	} else
201 		fileid_type = fh->fh_fileid_type;
202 
203 	if (fileid_type == FILEID_ROOT)
204 		dentry = dget(exp->ex_path.dentry);
205 	else {
206 		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
207 				data_left, fileid_type,
208 				nfsd_acceptable, exp);
209 	}
210 	if (dentry == NULL)
211 		goto out;
212 	if (IS_ERR(dentry)) {
213 		if (PTR_ERR(dentry) != -EINVAL)
214 			error = nfserrno(PTR_ERR(dentry));
215 		goto out;
216 	}
217 
218 	if (S_ISDIR(dentry->d_inode->i_mode) &&
219 			(dentry->d_flags & DCACHE_DISCONNECTED)) {
220 		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
221 				dentry->d_parent->d_name.name, dentry->d_name.name);
222 	}
223 
224 	fhp->fh_dentry = dentry;
225 	fhp->fh_export = exp;
226 	nfsd_nr_verified++;
227 	return 0;
228 out:
229 	exp_put(exp);
230 	return error;
231 }
232 
233 /*
234  * Perform sanity checks on the dentry in a client's file handle.
235  *
236  * Note that the file handle dentry may need to be freed even after
237  * an error return.
238  *
239  * This is only called at the start of an nfsproc call, so fhp points to
240  * a svc_fh which is all 0 except for the over-the-wire file handle.
241  */
242 __be32
243 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
244 {
245 	struct svc_export *exp;
246 	struct dentry	*dentry;
247 	__be32		error;
248 
249 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
250 
251 	if (!fhp->fh_dentry) {
252 		error = nfsd_set_fh_dentry(rqstp, fhp);
253 		if (error)
254 			goto out;
255 		dentry = fhp->fh_dentry;
256 		exp = fhp->fh_export;
257 	} else {
258 		/*
259 		 * just rechecking permissions
260 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create
261 		 * does as well)
262 		 */
263 		dprintk("nfsd: fh_verify - just checking\n");
264 		dentry = fhp->fh_dentry;
265 		exp = fhp->fh_export;
266 		/*
267 		 * Set user creds for this exportpoint; necessary even
268 		 * in the "just checking" case because this may be a
269 		 * filehandle that was created by fh_compose, and that
270 		 * is about to be used in another nfsv4 compound
271 		 * operation.
272 		 */
273 		error = nfsd_setuser_and_check_port(rqstp, exp);
274 		if (error)
275 			goto out;
276 	}
277 
278 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
279 	if (error)
280 		goto out;
281 
282 	if (!(access & MAY_LOCK)) {
283 		/*
284 		 * pseudoflavor restrictions are not enforced on NLM,
285 		 * which clients virtually always use auth_sys for,
286 		 * even while using RPCSEC_GSS for NFS.
287 		 */
288 		error = check_nfsd_access(exp, rqstp);
289 		if (error)
290 			goto out;
291 	}
292 
293 	/* Finally, check access permissions. */
294 	error = nfsd_permission(rqstp, exp, dentry, access);
295 
296 	if (error) {
297 		dprintk("fh_verify: %s/%s permission failure, "
298 			"acc=%x, error=%d\n",
299 			dentry->d_parent->d_name.name,
300 			dentry->d_name.name,
301 			access, ntohl(error));
302 	}
303 out:
304 	if (error == nfserr_stale)
305 		nfsdstats.fh_stale++;
306 	return error;
307 }
308 
309 
310 /*
311  * Compose a file handle for an NFS reply.
312  *
313  * Note that when first composed, the dentry may not yet have
314  * an inode.  In this case a call to fh_update should be made
315  * before the fh goes out on the wire ...
316  */
317 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
318 		struct dentry *dentry)
319 {
320 	if (dentry != exp->ex_path.dentry) {
321 		struct fid *fid = (struct fid *)
322 			(fhp->fh_handle.fh_auth + fhp->fh_handle.fh_size/4 - 1);
323 		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
324 		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
325 
326 		fhp->fh_handle.fh_fileid_type =
327 			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
328 		fhp->fh_handle.fh_size += maxsize * 4;
329 	} else {
330 		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
331 	}
332 }
333 
334 /*
335  * for composing old style file handles
336  */
337 static inline void _fh_update_old(struct dentry *dentry,
338 				  struct svc_export *exp,
339 				  struct knfsd_fh *fh)
340 {
341 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
342 	fh->ofh_generation = dentry->d_inode->i_generation;
343 	if (S_ISDIR(dentry->d_inode->i_mode) ||
344 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
345 		fh->ofh_dirino = 0;
346 }
347 
348 __be32
349 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
350 	   struct svc_fh *ref_fh)
351 {
352 	/* ref_fh is a reference file handle.
353 	 * if it is non-null and for the same filesystem, then we should compose
354 	 * a filehandle which is of the same version, where possible.
355 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
356 	 * Then create a 32byte filehandle using nfs_fhbase_old
357 	 *
358 	 */
359 
360 	u8 version;
361 	u8 fsid_type = 0;
362 	struct inode * inode = dentry->d_inode;
363 	struct dentry *parent = dentry->d_parent;
364 	__u32 *datap;
365 	dev_t ex_dev = exp->ex_path.dentry->d_inode->i_sb->s_dev;
366 	int root_export = (exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root);
367 
368 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
369 		MAJOR(ex_dev), MINOR(ex_dev),
370 		(long) exp->ex_path.dentry->d_inode->i_ino,
371 		parent->d_name.name, dentry->d_name.name,
372 		(inode ? inode->i_ino : 0));
373 
374 	/* Choose filehandle version and fsid type based on
375 	 * the reference filehandle (if it is in the same export)
376 	 * or the export options.
377 	 */
378  retry:
379 	version = 1;
380 	if (ref_fh && ref_fh->fh_export == exp) {
381 		version = ref_fh->fh_handle.fh_version;
382 		fsid_type = ref_fh->fh_handle.fh_fsid_type;
383 
384 		if (ref_fh == fhp)
385 			fh_put(ref_fh);
386 		ref_fh = NULL;
387 
388 		switch (version) {
389 		case 0xca:
390 			fsid_type = FSID_DEV;
391 			break;
392 		case 1:
393 			break;
394 		default:
395 			goto retry;
396 		}
397 
398 		/* Need to check that this type works for this
399 		 * export point.  As the fsid -> filesystem mapping
400 		 * was guided by user-space, there is no guarantee
401 		 * that the filesystem actually supports that fsid
402 		 * type. If it doesn't we loop around again without
403 		 * ref_fh set.
404 		 */
405 		switch(fsid_type) {
406 		case FSID_DEV:
407 			if (!old_valid_dev(ex_dev))
408 				goto retry;
409 			/* FALL THROUGH */
410 		case FSID_MAJOR_MINOR:
411 		case FSID_ENCODE_DEV:
412 			if (!(exp->ex_path.dentry->d_inode->i_sb->s_type->fs_flags
413 			      & FS_REQUIRES_DEV))
414 				goto retry;
415 			break;
416 		case FSID_NUM:
417 			if (! (exp->ex_flags & NFSEXP_FSID))
418 				goto retry;
419 			break;
420 		case FSID_UUID8:
421 		case FSID_UUID16:
422 			if (!root_export)
423 				goto retry;
424 			/* fall through */
425 		case FSID_UUID4_INUM:
426 		case FSID_UUID16_INUM:
427 			if (exp->ex_uuid == NULL)
428 				goto retry;
429 			break;
430 		}
431 	} else if (exp->ex_uuid) {
432 		if (fhp->fh_maxsize >= 64) {
433 			if (root_export)
434 				fsid_type = FSID_UUID16;
435 			else
436 				fsid_type = FSID_UUID16_INUM;
437 		} else {
438 			if (root_export)
439 				fsid_type = FSID_UUID8;
440 			else
441 				fsid_type = FSID_UUID4_INUM;
442 		}
443 	} else if (exp->ex_flags & NFSEXP_FSID)
444 		fsid_type = FSID_NUM;
445 	else if (!old_valid_dev(ex_dev))
446 		/* for newer device numbers, we must use a newer fsid format */
447 		fsid_type = FSID_ENCODE_DEV;
448 	else
449 		fsid_type = FSID_DEV;
450 
451 	if (ref_fh == fhp)
452 		fh_put(ref_fh);
453 
454 	if (fhp->fh_locked || fhp->fh_dentry) {
455 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
456 		       parent->d_name.name, dentry->d_name.name);
457 	}
458 	if (fhp->fh_maxsize < NFS_FHSIZE)
459 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
460 		       fhp->fh_maxsize,
461 		       parent->d_name.name, dentry->d_name.name);
462 
463 	fhp->fh_dentry = dget(dentry); /* our internal copy */
464 	fhp->fh_export = exp;
465 	cache_get(&exp->h);
466 
467 	if (version == 0xca) {
468 		/* old style filehandle please */
469 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
470 		fhp->fh_handle.fh_size = NFS_FHSIZE;
471 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
472 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
473 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
474 		fhp->fh_handle.ofh_xino =
475 			ino_t_to_u32(exp->ex_path.dentry->d_inode->i_ino);
476 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
477 		if (inode)
478 			_fh_update_old(dentry, exp, &fhp->fh_handle);
479 	} else {
480 		int len;
481 		fhp->fh_handle.fh_version = 1;
482 		fhp->fh_handle.fh_auth_type = 0;
483 		datap = fhp->fh_handle.fh_auth+0;
484 		fhp->fh_handle.fh_fsid_type = fsid_type;
485 		mk_fsid(fsid_type, datap, ex_dev,
486 			exp->ex_path.dentry->d_inode->i_ino,
487 			exp->ex_fsid, exp->ex_uuid);
488 
489 		len = key_len(fsid_type);
490 		datap += len/4;
491 		fhp->fh_handle.fh_size = 4 + len;
492 
493 		if (inode)
494 			_fh_update(fhp, exp, dentry);
495 		if (fhp->fh_handle.fh_fileid_type == 255)
496 			return nfserr_opnotsupp;
497 	}
498 
499 	nfsd_nr_verified++;
500 	return 0;
501 }
502 
503 /*
504  * Update file handle information after changing a dentry.
505  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
506  */
507 __be32
508 fh_update(struct svc_fh *fhp)
509 {
510 	struct dentry *dentry;
511 
512 	if (!fhp->fh_dentry)
513 		goto out_bad;
514 
515 	dentry = fhp->fh_dentry;
516 	if (!dentry->d_inode)
517 		goto out_negative;
518 	if (fhp->fh_handle.fh_version != 1) {
519 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
520 	} else {
521 		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
522 			goto out;
523 
524 		_fh_update(fhp, fhp->fh_export, dentry);
525 		if (fhp->fh_handle.fh_fileid_type == 255)
526 			return nfserr_opnotsupp;
527 	}
528 out:
529 	return 0;
530 
531 out_bad:
532 	printk(KERN_ERR "fh_update: fh not verified!\n");
533 	goto out;
534 out_negative:
535 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
536 		dentry->d_parent->d_name.name, dentry->d_name.name);
537 	goto out;
538 }
539 
540 /*
541  * Release a file handle.
542  */
543 void
544 fh_put(struct svc_fh *fhp)
545 {
546 	struct dentry * dentry = fhp->fh_dentry;
547 	struct svc_export * exp = fhp->fh_export;
548 	if (dentry) {
549 		fh_unlock(fhp);
550 		fhp->fh_dentry = NULL;
551 		dput(dentry);
552 #ifdef CONFIG_NFSD_V3
553 		fhp->fh_pre_saved = 0;
554 		fhp->fh_post_saved = 0;
555 #endif
556 		nfsd_nr_put++;
557 	}
558 	if (exp) {
559 		cache_put(&exp->h, &svc_export_cache);
560 		fhp->fh_export = NULL;
561 	}
562 	return;
563 }
564 
565 /*
566  * Shorthand for dprintk()'s
567  */
568 char * SVCFH_fmt(struct svc_fh *fhp)
569 {
570 	struct knfsd_fh *fh = &fhp->fh_handle;
571 
572 	static char buf[80];
573 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
574 		fh->fh_size,
575 		fh->fh_base.fh_pad[0],
576 		fh->fh_base.fh_pad[1],
577 		fh->fh_base.fh_pad[2],
578 		fh->fh_base.fh_pad[3],
579 		fh->fh_base.fh_pad[4],
580 		fh->fh_base.fh_pad[5]);
581 	return buf;
582 }
583 
584 enum fsid_source fsid_source(struct svc_fh *fhp)
585 {
586 	if (fhp->fh_handle.fh_version != 1)
587 		return FSIDSOURCE_DEV;
588 	switch(fhp->fh_handle.fh_fsid_type) {
589 	case FSID_DEV:
590 	case FSID_ENCODE_DEV:
591 	case FSID_MAJOR_MINOR:
592 		if (fhp->fh_export->ex_path.dentry->d_inode->i_sb->s_type->fs_flags
593 		    & FS_REQUIRES_DEV)
594 			return FSIDSOURCE_DEV;
595 		break;
596 	case FSID_NUM:
597 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
598 			return FSIDSOURCE_FSID;
599 		break;
600 	default:
601 		break;
602 	}
603 	/* either a UUID type filehandle, or the filehandle doesn't
604 	 * match the export.
605 	 */
606 	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
607 		return FSIDSOURCE_FSID;
608 	if (fhp->fh_export->ex_uuid)
609 		return FSIDSOURCE_UUID;
610 	return FSIDSOURCE_DEV;
611 }
612