xref: /linux/fs/nfsd/nfsfh.c (revision 6e8331ac6973435b1e7604c30f2ad394035b46e1) 
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/sched.h>
13 #include <linux/slab.h>
14 #include <linux/smp_lock.h>
15 #include <linux/fs.h>
16 #include <linux/unistd.h>
17 #include <linux/string.h>
18 #include <linux/stat.h>
19 #include <linux/dcache.h>
20 #include <linux/mount.h>
21 #include <asm/pgtable.h>
22 
23 #include <linux/sunrpc/svc.h>
24 #include <linux/nfsd/nfsd.h>
25 
26 #define NFSDDBG_FACILITY		NFSDDBG_FH
27 #define NFSD_PARANOIA 1
28 /* #define NFSD_DEBUG_VERBOSE 1 */
29 
30 
31 static int nfsd_nr_verified;
32 static int nfsd_nr_put;
33 
34 extern struct export_operations export_op_default;
35 
36 #define	CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
37 
38 /*
39  * our acceptability function.
40  * if NOSUBTREECHECK, accept anything
41  * if not, require that we can walk up to exp->ex_dentry
42  * doing some checks on the 'x' bits
43  */
44 static int nfsd_acceptable(void *expv, struct dentry *dentry)
45 {
46 	struct svc_export *exp = expv;
47 	int rv;
48 	struct dentry *tdentry;
49 	struct dentry *parent;
50 
51 	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
52 		return 1;
53 
54 	tdentry = dget(dentry);
55 	while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
56 		/* make sure parents give x permission to user */
57 		int err;
58 		parent = dget_parent(tdentry);
59 		err = permission(parent->d_inode, MAY_EXEC, NULL);
60 		if (err < 0) {
61 			dput(parent);
62 			break;
63 		}
64 		dput(tdentry);
65 		tdentry = parent;
66 	}
67 	if (tdentry != exp->ex_dentry)
68 		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
69 	rv = (tdentry == exp->ex_dentry);
70 	dput(tdentry);
71 	return rv;
72 }
73 
74 /* Type check. The correct error return for type mismatches does not seem to be
75  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
76  * comment in the NFSv3 spec says this is incorrect (implementation notes for
77  * the write call).
78  */
79 static inline int
80 nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
81 {
82 	/* Type can be negative when creating hardlinks - not to a dir */
83 	if (type > 0 && (mode & S_IFMT) != type) {
84 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
85 			return nfserr_symlink;
86 		else if (type == S_IFDIR)
87 			return nfserr_notdir;
88 		else if ((mode & S_IFMT) == S_IFDIR)
89 			return nfserr_isdir;
90 		else
91 			return nfserr_inval;
92 	}
93 	if (type < 0 && (mode & S_IFMT) == -type) {
94 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
95 			return nfserr_symlink;
96 		else if (type == -S_IFDIR)
97 			return nfserr_isdir;
98 		else
99 			return nfserr_notdir;
100 	}
101 	return 0;
102 }
103 
104 /*
105  * Perform sanity checks on the dentry in a client's file handle.
106  *
107  * Note that the file handle dentry may need to be freed even after
108  * an error return.
109  *
110  * This is only called at the start of an nfsproc call, so fhp points to
111  * a svc_fh which is all 0 except for the over-the-wire file handle.
112  */
113 u32
114 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
115 {
116 	struct knfsd_fh	*fh = &fhp->fh_handle;
117 	struct svc_export *exp = NULL;
118 	struct dentry	*dentry;
119 	u32		error = 0;
120 
121 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
122 
123 	/* keep this filehandle for possible reference  when encoding attributes */
124 	rqstp->rq_reffh = fh;
125 
126 	if (!fhp->fh_dentry) {
127 		__u32 *datap=NULL;
128 		__u32 tfh[3];		/* filehandle fragment for oldstyle filehandles */
129 		int fileid_type;
130 		int data_left = fh->fh_size/4;
131 
132 		error = nfserr_stale;
133 		if (rqstp->rq_client == NULL)
134 			goto out;
135 		if (rqstp->rq_vers > 2)
136 			error = nfserr_badhandle;
137 		if (rqstp->rq_vers == 4 && fh->fh_size == 0)
138 			return nfserr_nofilehandle;
139 
140 		if (fh->fh_version == 1) {
141 			int len;
142 			datap = fh->fh_auth;
143 			if (--data_left<0) goto out;
144 			switch (fh->fh_auth_type) {
145 			case 0: break;
146 			default: goto out;
147 			}
148 			len = key_len(fh->fh_fsid_type) / 4;
149 			if (len == 0) goto out;
150 			if  (fh->fh_fsid_type == 2) {
151 				/* deprecated, convert to type 3 */
152 				len = 3;
153 				fh->fh_fsid_type = 3;
154 				fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
155 				fh->fh_fsid[1] = fh->fh_fsid[2];
156 			}
157 			if ((data_left -= len)<0) goto out;
158 			exp = exp_find(rqstp->rq_client, fh->fh_fsid_type, datap, &rqstp->rq_chandle);
159 			datap += len;
160 		} else {
161 			dev_t xdev;
162 			ino_t xino;
163 			if (fh->fh_size != NFS_FHSIZE)
164 				goto out;
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_v0(tfh, xdev, xino);
169 			exp = exp_find(rqstp->rq_client, 0, tfh, &rqstp->rq_chandle);
170 		}
171 
172 		error = nfserr_dropit;
173 		if (IS_ERR(exp) && PTR_ERR(exp) == -EAGAIN)
174 			goto out;
175 
176 		error = nfserr_stale;
177 		if (!exp || IS_ERR(exp))
178 			goto out;
179 
180 		/* Check if the request originated from a secure port. */
181 		error = nfserr_perm;
182 		if (!rqstp->rq_secure && EX_SECURE(exp)) {
183 			printk(KERN_WARNING
184 			       "nfsd: request from insecure port (%u.%u.%u.%u:%d)!\n",
185 			       NIPQUAD(rqstp->rq_addr.sin_addr.s_addr),
186 			       ntohs(rqstp->rq_addr.sin_port));
187 			goto out;
188 		}
189 
190 		/* Set user creds for this exportpoint */
191 		error = nfserrno(nfsd_setuser(rqstp, exp));
192 		if (error)
193 			goto out;
194 
195 		/*
196 		 * Look up the dentry using the NFS file handle.
197 		 */
198 		error = nfserr_stale;
199 		if (rqstp->rq_vers > 2)
200 			error = nfserr_badhandle;
201 
202 		if (fh->fh_version != 1) {
203 			tfh[0] = fh->ofh_ino;
204 			tfh[1] = fh->ofh_generation;
205 			tfh[2] = fh->ofh_dirino;
206 			datap = tfh;
207 			data_left = 3;
208 			if (fh->ofh_dirino == 0)
209 				fileid_type = 1;
210 			else
211 				fileid_type = 2;
212 		} else
213 			fileid_type = fh->fh_fileid_type;
214 
215 		if (fileid_type == 0)
216 			dentry = dget(exp->ex_dentry);
217 		else {
218 			struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
219 			dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
220 						     datap, data_left,
221 						     fileid_type,
222 						     nfsd_acceptable, exp);
223 		}
224 		if (dentry == NULL)
225 			goto out;
226 		if (IS_ERR(dentry)) {
227 			if (PTR_ERR(dentry) != -EINVAL)
228 				error = nfserrno(PTR_ERR(dentry));
229 			goto out;
230 		}
231 #ifdef NFSD_PARANOIA
232 		if (S_ISDIR(dentry->d_inode->i_mode) &&
233 		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
234 			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
235 			       dentry->d_parent->d_name.name, dentry->d_name.name);
236 		}
237 #endif
238 
239 		fhp->fh_dentry = dentry;
240 		fhp->fh_export = exp;
241 		nfsd_nr_verified++;
242 	} else {
243 		/* just rechecking permissions
244 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
245 		 */
246 		dprintk("nfsd: fh_verify - just checking\n");
247 		dentry = fhp->fh_dentry;
248 		exp = fhp->fh_export;
249 		/* Set user creds for this exportpoint; necessary even
250 		 * in the "just checking" case because this may be a
251 		 * filehandle that was created by fh_compose, and that
252 		 * is about to be used in another nfsv4 compound
253 		 * operation */
254 		error = nfserrno(nfsd_setuser(rqstp, exp));
255 		if (error)
256 			goto out;
257 	}
258 	cache_get(&exp->h);
259 
260 
261 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
262 	if (error)
263 		goto out;
264 
265 	/* Finally, check access permissions. */
266 	error = nfsd_permission(exp, dentry, access);
267 
268 #ifdef NFSD_PARANOIA_EXTREME
269 	if (error) {
270 		printk("fh_verify: %s/%s permission failure, acc=%x, error=%d\n",
271 		       dentry->d_parent->d_name.name, dentry->d_name.name, access, (error >> 24));
272 	}
273 #endif
274 out:
275 	if (exp && !IS_ERR(exp))
276 		exp_put(exp);
277 	if (error == nfserr_stale)
278 		nfsdstats.fh_stale++;
279 	return error;
280 }
281 
282 
283 /*
284  * Compose a file handle for an NFS reply.
285  *
286  * Note that when first composed, the dentry may not yet have
287  * an inode.  In this case a call to fh_update should be made
288  * before the fh goes out on the wire ...
289  */
290 static inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
291 			     __u32 *datap, int *maxsize)
292 {
293 	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
294 
295 	if (dentry == exp->ex_dentry) {
296 		*maxsize = 0;
297 		return 0;
298 	}
299 
300 	return CALL(nop,encode_fh)(dentry, datap, maxsize,
301 			  !(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
302 }
303 
304 /*
305  * for composing old style file handles
306  */
307 static inline void _fh_update_old(struct dentry *dentry,
308 				  struct svc_export *exp,
309 				  struct knfsd_fh *fh)
310 {
311 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
312 	fh->ofh_generation = dentry->d_inode->i_generation;
313 	if (S_ISDIR(dentry->d_inode->i_mode) ||
314 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
315 		fh->ofh_dirino = 0;
316 }
317 
318 int
319 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry, struct svc_fh *ref_fh)
320 {
321 	/* ref_fh is a reference file handle.
322 	 * if it is non-null and for the same filesystem, then we should compose
323 	 * a filehandle which is of the same version, where possible.
324 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
325 	 * Then create a 32byte filehandle using nfs_fhbase_old
326 	 *
327 	 */
328 
329 	u8 ref_fh_version = 0;
330 	u8 ref_fh_fsid_type = 0;
331 	struct inode * inode = dentry->d_inode;
332 	struct dentry *parent = dentry->d_parent;
333 	__u32 *datap;
334 	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
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 	if (ref_fh && ref_fh->fh_export == exp) {
343 		ref_fh_version = ref_fh->fh_handle.fh_version;
344 		if (ref_fh_version == 0xca)
345 			ref_fh_fsid_type = 0;
346 		else
347 			ref_fh_fsid_type = ref_fh->fh_handle.fh_fsid_type;
348 		if (ref_fh_fsid_type > 3)
349 			ref_fh_fsid_type = 0;
350 
351 		/* make sure ref_fh type works for given export */
352 		if (ref_fh_fsid_type == 1 &&
353 		    !(exp->ex_flags & NFSEXP_FSID)) {
354 			/* if we don't have an fsid, we cannot provide one... */
355 			ref_fh_fsid_type = 0;
356 		}
357 	} else if (exp->ex_flags & NFSEXP_FSID)
358 		ref_fh_fsid_type = 1;
359 
360 	if (!old_valid_dev(ex_dev) && ref_fh_fsid_type == 0) {
361 		/* for newer device numbers, we must use a newer fsid format */
362 		ref_fh_version = 1;
363 		ref_fh_fsid_type = 3;
364 	}
365 	if (old_valid_dev(ex_dev) &&
366 	    (ref_fh_fsid_type == 2 || ref_fh_fsid_type == 3))
367 		/* must use type1 for smaller device numbers */
368 		ref_fh_fsid_type = 0;
369 
370 	if (ref_fh == fhp)
371 		fh_put(ref_fh);
372 
373 	if (fhp->fh_locked || fhp->fh_dentry) {
374 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
375 			parent->d_name.name, dentry->d_name.name);
376 	}
377 	if (fhp->fh_maxsize < NFS_FHSIZE)
378 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
379 		       fhp->fh_maxsize, parent->d_name.name, dentry->d_name.name);
380 
381 	fhp->fh_dentry = dget(dentry); /* our internal copy */
382 	fhp->fh_export = exp;
383 	cache_get(&exp->h);
384 
385 	if (ref_fh_version == 0xca) {
386 		/* old style filehandle please */
387 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
388 		fhp->fh_handle.fh_size = NFS_FHSIZE;
389 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
390 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
391 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
392 		fhp->fh_handle.ofh_xino = ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
393 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
394 		if (inode)
395 			_fh_update_old(dentry, exp, &fhp->fh_handle);
396 	} else {
397 		int len;
398 		fhp->fh_handle.fh_version = 1;
399 		fhp->fh_handle.fh_auth_type = 0;
400 		datap = fhp->fh_handle.fh_auth+0;
401 		fhp->fh_handle.fh_fsid_type = ref_fh_fsid_type;
402 		switch (ref_fh_fsid_type) {
403 			case 0:
404 				/*
405 				 * fsid_type 0:
406 				 * 2byte major, 2byte minor, 4byte inode
407 				 */
408 				mk_fsid_v0(datap, ex_dev,
409 					exp->ex_dentry->d_inode->i_ino);
410 				break;
411 			case 1:
412 				/* fsid_type 1 == 4 bytes filesystem id */
413 				mk_fsid_v1(datap, exp->ex_fsid);
414 				break;
415 			case 2:
416 				/*
417 				 * fsid_type 2:
418 				 * 4byte major, 4byte minor, 4byte inode
419 				 */
420 				mk_fsid_v2(datap, ex_dev,
421 					exp->ex_dentry->d_inode->i_ino);
422 				break;
423 			case 3:
424 				/*
425 				 * fsid_type 3:
426 				 * 4byte devicenumber, 4byte inode
427 				 */
428 				mk_fsid_v3(datap, ex_dev,
429 					exp->ex_dentry->d_inode->i_ino);
430 				break;
431 		}
432 		len = key_len(ref_fh_fsid_type);
433 		datap += len/4;
434 		fhp->fh_handle.fh_size = 4 + len;
435 
436 		if (inode) {
437 			int size = (fhp->fh_maxsize-len-4)/4;
438 			fhp->fh_handle.fh_fileid_type =
439 				_fh_update(dentry, exp, datap, &size);
440 			fhp->fh_handle.fh_size += size*4;
441 		}
442 		if (fhp->fh_handle.fh_fileid_type == 255)
443 			return nfserr_opnotsupp;
444 	}
445 
446 	nfsd_nr_verified++;
447 	return 0;
448 }
449 
450 /*
451  * Update file handle information after changing a dentry.
452  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
453  */
454 int
455 fh_update(struct svc_fh *fhp)
456 {
457 	struct dentry *dentry;
458 	__u32 *datap;
459 
460 	if (!fhp->fh_dentry)
461 		goto out_bad;
462 
463 	dentry = fhp->fh_dentry;
464 	if (!dentry->d_inode)
465 		goto out_negative;
466 	if (fhp->fh_handle.fh_version != 1) {
467 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
468 	} else {
469 		int size;
470 		if (fhp->fh_handle.fh_fileid_type != 0)
471 			goto out;
472 		datap = fhp->fh_handle.fh_auth+
473 			fhp->fh_handle.fh_size/4 -1;
474 		size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
475 		fhp->fh_handle.fh_fileid_type =
476 			_fh_update(dentry, fhp->fh_export, datap, &size);
477 		fhp->fh_handle.fh_size += size*4;
478 		if (fhp->fh_handle.fh_fileid_type == 255)
479 			return nfserr_opnotsupp;
480 	}
481 out:
482 	return 0;
483 
484 out_bad:
485 	printk(KERN_ERR "fh_update: fh not verified!\n");
486 	goto out;
487 out_negative:
488 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
489 		dentry->d_parent->d_name.name, dentry->d_name.name);
490 	goto out;
491 }
492 
493 /*
494  * Release a file handle.
495  */
496 void
497 fh_put(struct svc_fh *fhp)
498 {
499 	struct dentry * dentry = fhp->fh_dentry;
500 	struct svc_export * exp = fhp->fh_export;
501 	if (dentry) {
502 		fh_unlock(fhp);
503 		fhp->fh_dentry = NULL;
504 		dput(dentry);
505 #ifdef CONFIG_NFSD_V3
506 		fhp->fh_pre_saved = 0;
507 		fhp->fh_post_saved = 0;
508 #endif
509 		nfsd_nr_put++;
510 	}
511 	if (exp) {
512 		cache_put(&exp->h, &svc_export_cache);
513 		fhp->fh_export = NULL;
514 	}
515 	return;
516 }
517 
518 /*
519  * Shorthand for dprintk()'s
520  */
521 char * SVCFH_fmt(struct svc_fh *fhp)
522 {
523 	struct knfsd_fh *fh = &fhp->fh_handle;
524 
525 	static char buf[80];
526 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
527 		fh->fh_size,
528 		fh->fh_base.fh_pad[0],
529 		fh->fh_base.fh_pad[1],
530 		fh->fh_base.fh_pad[2],
531 		fh->fh_base.fh_pad[3],
532 		fh->fh_base.fh_pad[4],
533 		fh->fh_base.fh_pad[5]);
534 	return buf;
535 }
536