xref: /linux/fs/nfsd/nfsfh.c (revision 14b42963f64b98ab61fa9723c03d71aa5ef4f862) 
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 		/*
191 		 * Look up the dentry using the NFS file handle.
192 		 */
193 		error = nfserr_stale;
194 		if (rqstp->rq_vers > 2)
195 			error = nfserr_badhandle;
196 
197 		if (fh->fh_version != 1) {
198 			tfh[0] = fh->ofh_ino;
199 			tfh[1] = fh->ofh_generation;
200 			tfh[2] = fh->ofh_dirino;
201 			datap = tfh;
202 			data_left = 3;
203 			if (fh->ofh_dirino == 0)
204 				fileid_type = 1;
205 			else
206 				fileid_type = 2;
207 		} else
208 			fileid_type = fh->fh_fileid_type;
209 
210 		if (fileid_type == 0)
211 			dentry = dget(exp->ex_dentry);
212 		else {
213 			struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
214 			dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
215 						     datap, data_left,
216 						     fileid_type,
217 						     nfsd_acceptable, exp);
218 		}
219 		if (dentry == NULL)
220 			goto out;
221 		if (IS_ERR(dentry)) {
222 			if (PTR_ERR(dentry) != -EINVAL)
223 				error = nfserrno(PTR_ERR(dentry));
224 			goto out;
225 		}
226 #ifdef NFSD_PARANOIA
227 		if (S_ISDIR(dentry->d_inode->i_mode) &&
228 		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
229 			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
230 			       dentry->d_parent->d_name.name, dentry->d_name.name);
231 		}
232 #endif
233 
234 		fhp->fh_dentry = dentry;
235 		fhp->fh_export = exp;
236 		nfsd_nr_verified++;
237 	} else {
238 		/* just rechecking permissions
239 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
240 		 */
241 		dprintk("nfsd: fh_verify - just checking\n");
242 		dentry = fhp->fh_dentry;
243 		exp = fhp->fh_export;
244 	}
245 	cache_get(&exp->h);
246 
247 	/* Set user creds for this exportpoint; necessary even in the "just
248 	 * checking" case because this may be a filehandle that was created by
249 	 * fh_compose, and that 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 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
256 	if (error)
257 		goto out;
258 
259 	/* Finally, check access permissions. */
260 	error = nfsd_permission(exp, dentry, access);
261 
262 #ifdef NFSD_PARANOIA_EXTREME
263 	if (error) {
264 		printk("fh_verify: %s/%s permission failure, acc=%x, error=%d\n",
265 		       dentry->d_parent->d_name.name, dentry->d_name.name, access, (error >> 24));
266 	}
267 #endif
268 out:
269 	if (exp && !IS_ERR(exp))
270 		exp_put(exp);
271 	if (error == nfserr_stale)
272 		nfsdstats.fh_stale++;
273 	return error;
274 }
275 
276 
277 /*
278  * Compose a file handle for an NFS reply.
279  *
280  * Note that when first composed, the dentry may not yet have
281  * an inode.  In this case a call to fh_update should be made
282  * before the fh goes out on the wire ...
283  */
284 static inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
285 			     __u32 *datap, int *maxsize)
286 {
287 	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
288 
289 	if (dentry == exp->ex_dentry) {
290 		*maxsize = 0;
291 		return 0;
292 	}
293 
294 	return CALL(nop,encode_fh)(dentry, datap, maxsize,
295 			  !(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
296 }
297 
298 /*
299  * for composing old style file handles
300  */
301 static inline void _fh_update_old(struct dentry *dentry,
302 				  struct svc_export *exp,
303 				  struct knfsd_fh *fh)
304 {
305 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
306 	fh->ofh_generation = dentry->d_inode->i_generation;
307 	if (S_ISDIR(dentry->d_inode->i_mode) ||
308 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
309 		fh->ofh_dirino = 0;
310 }
311 
312 int
313 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry, struct svc_fh *ref_fh)
314 {
315 	/* ref_fh is a reference file handle.
316 	 * if it is non-null and for the same filesystem, then we should compose
317 	 * a filehandle which is of the same version, where possible.
318 	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
319 	 * Then create a 32byte filehandle using nfs_fhbase_old
320 	 *
321 	 */
322 
323 	u8 ref_fh_version = 0;
324 	u8 ref_fh_fsid_type = 0;
325 	struct inode * inode = dentry->d_inode;
326 	struct dentry *parent = dentry->d_parent;
327 	__u32 *datap;
328 	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
329 
330 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
331 		MAJOR(ex_dev), MINOR(ex_dev),
332 		(long) exp->ex_dentry->d_inode->i_ino,
333 		parent->d_name.name, dentry->d_name.name,
334 		(inode ? inode->i_ino : 0));
335 
336 	if (ref_fh && ref_fh->fh_export == exp) {
337 		ref_fh_version = ref_fh->fh_handle.fh_version;
338 		if (ref_fh_version == 0xca)
339 			ref_fh_fsid_type = 0;
340 		else
341 			ref_fh_fsid_type = ref_fh->fh_handle.fh_fsid_type;
342 		if (ref_fh_fsid_type > 3)
343 			ref_fh_fsid_type = 0;
344 
345 		/* make sure ref_fh type works for given export */
346 		if (ref_fh_fsid_type == 1 &&
347 		    !(exp->ex_flags & NFSEXP_FSID)) {
348 			/* if we don't have an fsid, we cannot provide one... */
349 			ref_fh_fsid_type = 0;
350 		}
351 	} else if (exp->ex_flags & NFSEXP_FSID)
352 		ref_fh_fsid_type = 1;
353 
354 	if (!old_valid_dev(ex_dev) && ref_fh_fsid_type == 0) {
355 		/* for newer device numbers, we must use a newer fsid format */
356 		ref_fh_version = 1;
357 		ref_fh_fsid_type = 3;
358 	}
359 	if (old_valid_dev(ex_dev) &&
360 	    (ref_fh_fsid_type == 2 || ref_fh_fsid_type == 3))
361 		/* must use type1 for smaller device numbers */
362 		ref_fh_fsid_type = 0;
363 
364 	if (ref_fh == fhp)
365 		fh_put(ref_fh);
366 
367 	if (fhp->fh_locked || fhp->fh_dentry) {
368 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
369 			parent->d_name.name, dentry->d_name.name);
370 	}
371 	if (fhp->fh_maxsize < NFS_FHSIZE)
372 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
373 		       fhp->fh_maxsize, parent->d_name.name, dentry->d_name.name);
374 
375 	fhp->fh_dentry = dget(dentry); /* our internal copy */
376 	fhp->fh_export = exp;
377 	cache_get(&exp->h);
378 
379 	if (ref_fh_version == 0xca) {
380 		/* old style filehandle please */
381 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
382 		fhp->fh_handle.fh_size = NFS_FHSIZE;
383 		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
384 		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
385 		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
386 		fhp->fh_handle.ofh_xino = ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
387 		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
388 		if (inode)
389 			_fh_update_old(dentry, exp, &fhp->fh_handle);
390 	} else {
391 		int len;
392 		fhp->fh_handle.fh_version = 1;
393 		fhp->fh_handle.fh_auth_type = 0;
394 		datap = fhp->fh_handle.fh_auth+0;
395 		fhp->fh_handle.fh_fsid_type = ref_fh_fsid_type;
396 		switch (ref_fh_fsid_type) {
397 			case 0:
398 				/*
399 				 * fsid_type 0:
400 				 * 2byte major, 2byte minor, 4byte inode
401 				 */
402 				mk_fsid_v0(datap, ex_dev,
403 					exp->ex_dentry->d_inode->i_ino);
404 				break;
405 			case 1:
406 				/* fsid_type 1 == 4 bytes filesystem id */
407 				mk_fsid_v1(datap, exp->ex_fsid);
408 				break;
409 			case 2:
410 				/*
411 				 * fsid_type 2:
412 				 * 4byte major, 4byte minor, 4byte inode
413 				 */
414 				mk_fsid_v2(datap, ex_dev,
415 					exp->ex_dentry->d_inode->i_ino);
416 				break;
417 			case 3:
418 				/*
419 				 * fsid_type 3:
420 				 * 4byte devicenumber, 4byte inode
421 				 */
422 				mk_fsid_v3(datap, ex_dev,
423 					exp->ex_dentry->d_inode->i_ino);
424 				break;
425 		}
426 		len = key_len(ref_fh_fsid_type);
427 		datap += len/4;
428 		fhp->fh_handle.fh_size = 4 + len;
429 
430 		if (inode) {
431 			int size = (fhp->fh_maxsize-len-4)/4;
432 			fhp->fh_handle.fh_fileid_type =
433 				_fh_update(dentry, exp, datap, &size);
434 			fhp->fh_handle.fh_size += size*4;
435 		}
436 		if (fhp->fh_handle.fh_fileid_type == 255)
437 			return nfserr_opnotsupp;
438 	}
439 
440 	nfsd_nr_verified++;
441 	return 0;
442 }
443 
444 /*
445  * Update file handle information after changing a dentry.
446  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
447  */
448 int
449 fh_update(struct svc_fh *fhp)
450 {
451 	struct dentry *dentry;
452 	__u32 *datap;
453 
454 	if (!fhp->fh_dentry)
455 		goto out_bad;
456 
457 	dentry = fhp->fh_dentry;
458 	if (!dentry->d_inode)
459 		goto out_negative;
460 	if (fhp->fh_handle.fh_version != 1) {
461 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
462 	} else {
463 		int size;
464 		if (fhp->fh_handle.fh_fileid_type != 0)
465 			goto out;
466 		datap = fhp->fh_handle.fh_auth+
467 			fhp->fh_handle.fh_size/4 -1;
468 		size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
469 		fhp->fh_handle.fh_fileid_type =
470 			_fh_update(dentry, fhp->fh_export, datap, &size);
471 		fhp->fh_handle.fh_size += size*4;
472 		if (fhp->fh_handle.fh_fileid_type == 255)
473 			return nfserr_opnotsupp;
474 	}
475 out:
476 	return 0;
477 
478 out_bad:
479 	printk(KERN_ERR "fh_update: fh not verified!\n");
480 	goto out;
481 out_negative:
482 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
483 		dentry->d_parent->d_name.name, dentry->d_name.name);
484 	goto out;
485 }
486 
487 /*
488  * Release a file handle.
489  */
490 void
491 fh_put(struct svc_fh *fhp)
492 {
493 	struct dentry * dentry = fhp->fh_dentry;
494 	struct svc_export * exp = fhp->fh_export;
495 	if (dentry) {
496 		fh_unlock(fhp);
497 		fhp->fh_dentry = NULL;
498 		dput(dentry);
499 #ifdef CONFIG_NFSD_V3
500 		fhp->fh_pre_saved = 0;
501 		fhp->fh_post_saved = 0;
502 #endif
503 		nfsd_nr_put++;
504 	}
505 	if (exp) {
506 		cache_put(&exp->h, &svc_export_cache);
507 		fhp->fh_export = NULL;
508 	}
509 	return;
510 }
511 
512 /*
513  * Shorthand for dprintk()'s
514  */
515 char * SVCFH_fmt(struct svc_fh *fhp)
516 {
517 	struct knfsd_fh *fh = &fhp->fh_handle;
518 
519 	static char buf[80];
520 	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
521 		fh->fh_size,
522 		fh->fh_base.fh_pad[0],
523 		fh->fh_base.fh_pad[1],
524 		fh->fh_base.fh_pad[2],
525 		fh->fh_base.fh_pad[3],
526 		fh->fh_base.fh_pad[4],
527 		fh->fh_base.fh_pad[5]);
528 	return buf;
529 }
530