xref: /linux/fs/nfs/mount_clnt.c (revision 44f57d78) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * In-kernel MOUNT protocol client
4  *
5  * Copyright (C) 1997, Olaf Kirch <okir@monad.swb.de>
6  */
7 
8 #include <linux/types.h>
9 #include <linux/socket.h>
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/uio.h>
13 #include <linux/net.h>
14 #include <linux/in.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/sunrpc/sched.h>
17 #include <linux/nfs_fs.h>
18 #include "internal.h"
19 
20 #define NFSDBG_FACILITY	NFSDBG_MOUNT
21 
22 /*
23  * Defined by RFC 1094, section A.3; and RFC 1813, section 5.1.4
24  */
25 #define MNTPATHLEN		(1024)
26 
27 /*
28  * XDR data type sizes
29  */
30 #define encode_dirpath_sz	(1 + XDR_QUADLEN(MNTPATHLEN))
31 #define MNT_status_sz		(1)
32 #define MNT_fhs_status_sz	(1)
33 #define MNT_fhandle_sz		XDR_QUADLEN(NFS2_FHSIZE)
34 #define MNT_fhandle3_sz		(1 + XDR_QUADLEN(NFS3_FHSIZE))
35 #define MNT_authflav3_sz	(1 + NFS_MAX_SECFLAVORS)
36 
37 /*
38  * XDR argument and result sizes
39  */
40 #define MNT_enc_dirpath_sz	encode_dirpath_sz
41 #define MNT_dec_mountres_sz	(MNT_status_sz + MNT_fhandle_sz)
42 #define MNT_dec_mountres3_sz	(MNT_status_sz + MNT_fhandle_sz + \
43 				 MNT_authflav3_sz)
44 
45 /*
46  * Defined by RFC 1094, section A.5
47  */
48 enum {
49 	MOUNTPROC_NULL		= 0,
50 	MOUNTPROC_MNT		= 1,
51 	MOUNTPROC_DUMP		= 2,
52 	MOUNTPROC_UMNT		= 3,
53 	MOUNTPROC_UMNTALL	= 4,
54 	MOUNTPROC_EXPORT	= 5,
55 };
56 
57 /*
58  * Defined by RFC 1813, section 5.2
59  */
60 enum {
61 	MOUNTPROC3_NULL		= 0,
62 	MOUNTPROC3_MNT		= 1,
63 	MOUNTPROC3_DUMP		= 2,
64 	MOUNTPROC3_UMNT		= 3,
65 	MOUNTPROC3_UMNTALL	= 4,
66 	MOUNTPROC3_EXPORT	= 5,
67 };
68 
69 static const struct rpc_program mnt_program;
70 
71 /*
72  * Defined by OpenGroup XNFS Version 3W, chapter 8
73  */
74 enum mountstat {
75 	MNT_OK			= 0,
76 	MNT_EPERM		= 1,
77 	MNT_ENOENT		= 2,
78 	MNT_EACCES		= 13,
79 	MNT_EINVAL		= 22,
80 };
81 
82 static struct {
83 	u32 status;
84 	int errno;
85 } mnt_errtbl[] = {
86 	{ .status = MNT_OK,			.errno = 0,		},
87 	{ .status = MNT_EPERM,			.errno = -EPERM,	},
88 	{ .status = MNT_ENOENT,			.errno = -ENOENT,	},
89 	{ .status = MNT_EACCES,			.errno = -EACCES,	},
90 	{ .status = MNT_EINVAL,			.errno = -EINVAL,	},
91 };
92 
93 /*
94  * Defined by RFC 1813, section 5.1.5
95  */
96 enum mountstat3 {
97 	MNT3_OK			= 0,		/* no error */
98 	MNT3ERR_PERM		= 1,		/* Not owner */
99 	MNT3ERR_NOENT		= 2,		/* No such file or directory */
100 	MNT3ERR_IO		= 5,		/* I/O error */
101 	MNT3ERR_ACCES		= 13,		/* Permission denied */
102 	MNT3ERR_NOTDIR		= 20,		/* Not a directory */
103 	MNT3ERR_INVAL		= 22,		/* Invalid argument */
104 	MNT3ERR_NAMETOOLONG	= 63,		/* Filename too long */
105 	MNT3ERR_NOTSUPP		= 10004,	/* Operation not supported */
106 	MNT3ERR_SERVERFAULT	= 10006,	/* A failure on the server */
107 };
108 
109 static struct {
110 	u32 status;
111 	int errno;
112 } mnt3_errtbl[] = {
113 	{ .status = MNT3_OK,			.errno = 0,		},
114 	{ .status = MNT3ERR_PERM,		.errno = -EPERM,	},
115 	{ .status = MNT3ERR_NOENT,		.errno = -ENOENT,	},
116 	{ .status = MNT3ERR_IO,			.errno = -EIO,		},
117 	{ .status = MNT3ERR_ACCES,		.errno = -EACCES,	},
118 	{ .status = MNT3ERR_NOTDIR,		.errno = -ENOTDIR,	},
119 	{ .status = MNT3ERR_INVAL,		.errno = -EINVAL,	},
120 	{ .status = MNT3ERR_NAMETOOLONG,	.errno = -ENAMETOOLONG,	},
121 	{ .status = MNT3ERR_NOTSUPP,		.errno = -ENOTSUPP,	},
122 	{ .status = MNT3ERR_SERVERFAULT,	.errno = -EREMOTEIO,	},
123 };
124 
125 struct mountres {
126 	int errno;
127 	struct nfs_fh *fh;
128 	unsigned int *auth_count;
129 	rpc_authflavor_t *auth_flavors;
130 };
131 
132 struct mnt_fhstatus {
133 	u32 status;
134 	struct nfs_fh *fh;
135 };
136 
137 /**
138  * nfs_mount - Obtain an NFS file handle for the given host and path
139  * @info: pointer to mount request arguments
140  *
141  * Uses default timeout parameters specified by underlying transport. On
142  * successful return, the auth_flavs list and auth_flav_len will be populated
143  * with the list from the server or a faked-up list if the server didn't
144  * provide one.
145  */
146 int nfs_mount(struct nfs_mount_request *info)
147 {
148 	struct mountres	result = {
149 		.fh		= info->fh,
150 		.auth_count	= info->auth_flav_len,
151 		.auth_flavors	= info->auth_flavs,
152 	};
153 	struct rpc_message msg	= {
154 		.rpc_argp	= info->dirpath,
155 		.rpc_resp	= &result,
156 	};
157 	struct rpc_create_args args = {
158 		.net		= info->net,
159 		.protocol	= info->protocol,
160 		.address	= info->sap,
161 		.addrsize	= info->salen,
162 		.servername	= info->hostname,
163 		.program	= &mnt_program,
164 		.version	= info->version,
165 		.authflavor	= RPC_AUTH_UNIX,
166 		.cred		= current_cred(),
167 	};
168 	struct rpc_clnt		*mnt_clnt;
169 	int			status;
170 
171 	dprintk("NFS: sending MNT request for %s:%s\n",
172 		(info->hostname ? info->hostname : "server"),
173 			info->dirpath);
174 
175 	if (strlen(info->dirpath) > MNTPATHLEN)
176 		return -ENAMETOOLONG;
177 
178 	if (info->noresvport)
179 		args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
180 
181 	mnt_clnt = rpc_create(&args);
182 	if (IS_ERR(mnt_clnt))
183 		goto out_clnt_err;
184 
185 	if (info->version == NFS_MNT3_VERSION)
186 		msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC3_MNT];
187 	else
188 		msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC_MNT];
189 
190 	status = rpc_call_sync(mnt_clnt, &msg, RPC_TASK_SOFT|RPC_TASK_TIMEOUT);
191 	rpc_shutdown_client(mnt_clnt);
192 
193 	if (status < 0)
194 		goto out_call_err;
195 	if (result.errno != 0)
196 		goto out_mnt_err;
197 
198 	dprintk("NFS: MNT request succeeded\n");
199 	status = 0;
200 
201 	/*
202 	 * If the server didn't provide a flavor list, allow the
203 	 * client to try any flavor.
204 	 */
205 	if (info->version != NFS_MNT3_VERSION || *info->auth_flav_len == 0) {
206 		dprintk("NFS: Faking up auth_flavs list\n");
207 		info->auth_flavs[0] = RPC_AUTH_NULL;
208 		*info->auth_flav_len = 1;
209 	}
210 out:
211 	return status;
212 
213 out_clnt_err:
214 	status = PTR_ERR(mnt_clnt);
215 	dprintk("NFS: failed to create MNT RPC client, status=%d\n", status);
216 	goto out;
217 
218 out_call_err:
219 	dprintk("NFS: MNT request failed, status=%d\n", status);
220 	goto out;
221 
222 out_mnt_err:
223 	dprintk("NFS: MNT server returned result %d\n", result.errno);
224 	status = result.errno;
225 	goto out;
226 }
227 
228 /**
229  * nfs_umount - Notify a server that we have unmounted this export
230  * @info: pointer to umount request arguments
231  *
232  * MOUNTPROC_UMNT is advisory, so we set a short timeout, and always
233  * use UDP.
234  */
235 void nfs_umount(const struct nfs_mount_request *info)
236 {
237 	static const struct rpc_timeout nfs_umnt_timeout = {
238 		.to_initval = 1 * HZ,
239 		.to_maxval = 3 * HZ,
240 		.to_retries = 2,
241 	};
242 	struct rpc_create_args args = {
243 		.net		= info->net,
244 		.protocol	= IPPROTO_UDP,
245 		.address	= info->sap,
246 		.addrsize	= info->salen,
247 		.timeout	= &nfs_umnt_timeout,
248 		.servername	= info->hostname,
249 		.program	= &mnt_program,
250 		.version	= info->version,
251 		.authflavor	= RPC_AUTH_UNIX,
252 		.flags		= RPC_CLNT_CREATE_NOPING,
253 		.cred		= current_cred(),
254 	};
255 	struct rpc_message msg	= {
256 		.rpc_argp	= info->dirpath,
257 	};
258 	struct rpc_clnt *clnt;
259 	int status;
260 
261 	if (strlen(info->dirpath) > MNTPATHLEN)
262 		return;
263 
264 	if (info->noresvport)
265 		args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
266 
267 	clnt = rpc_create(&args);
268 	if (IS_ERR(clnt))
269 		goto out_clnt_err;
270 
271 	dprintk("NFS: sending UMNT request for %s:%s\n",
272 		(info->hostname ? info->hostname : "server"), info->dirpath);
273 
274 	if (info->version == NFS_MNT3_VERSION)
275 		msg.rpc_proc = &clnt->cl_procinfo[MOUNTPROC3_UMNT];
276 	else
277 		msg.rpc_proc = &clnt->cl_procinfo[MOUNTPROC_UMNT];
278 
279 	status = rpc_call_sync(clnt, &msg, 0);
280 	rpc_shutdown_client(clnt);
281 
282 	if (unlikely(status < 0))
283 		goto out_call_err;
284 
285 	return;
286 
287 out_clnt_err:
288 	dprintk("NFS: failed to create UMNT RPC client, status=%ld\n",
289 			PTR_ERR(clnt));
290 	return;
291 
292 out_call_err:
293 	dprintk("NFS: UMNT request failed, status=%d\n", status);
294 }
295 
296 /*
297  * XDR encode/decode functions for MOUNT
298  */
299 
300 static void encode_mntdirpath(struct xdr_stream *xdr, const char *pathname)
301 {
302 	const u32 pathname_len = strlen(pathname);
303 	__be32 *p;
304 
305 	p = xdr_reserve_space(xdr, 4 + pathname_len);
306 	xdr_encode_opaque(p, pathname, pathname_len);
307 }
308 
309 static void mnt_xdr_enc_dirpath(struct rpc_rqst *req, struct xdr_stream *xdr,
310 				const void *dirpath)
311 {
312 	encode_mntdirpath(xdr, dirpath);
313 }
314 
315 /*
316  * RFC 1094: "A non-zero status indicates some sort of error.  In this
317  * case, the status is a UNIX error number."  This can be problematic
318  * if the server and client use different errno values for the same
319  * error.
320  *
321  * However, the OpenGroup XNFS spec provides a simple mapping that is
322  * independent of local errno values on the server and the client.
323  */
324 static int decode_status(struct xdr_stream *xdr, struct mountres *res)
325 {
326 	unsigned int i;
327 	u32 status;
328 	__be32 *p;
329 
330 	p = xdr_inline_decode(xdr, 4);
331 	if (unlikely(p == NULL))
332 		return -EIO;
333 	status = be32_to_cpup(p);
334 
335 	for (i = 0; i < ARRAY_SIZE(mnt_errtbl); i++) {
336 		if (mnt_errtbl[i].status == status) {
337 			res->errno = mnt_errtbl[i].errno;
338 			return 0;
339 		}
340 	}
341 
342 	dprintk("NFS: unrecognized MNT status code: %u\n", status);
343 	res->errno = -EACCES;
344 	return 0;
345 }
346 
347 static int decode_fhandle(struct xdr_stream *xdr, struct mountres *res)
348 {
349 	struct nfs_fh *fh = res->fh;
350 	__be32 *p;
351 
352 	p = xdr_inline_decode(xdr, NFS2_FHSIZE);
353 	if (unlikely(p == NULL))
354 		return -EIO;
355 
356 	fh->size = NFS2_FHSIZE;
357 	memcpy(fh->data, p, NFS2_FHSIZE);
358 	return 0;
359 }
360 
361 static int mnt_xdr_dec_mountres(struct rpc_rqst *req,
362 				struct xdr_stream *xdr,
363 				void *data)
364 {
365 	struct mountres *res = data;
366 	int status;
367 
368 	status = decode_status(xdr, res);
369 	if (unlikely(status != 0 || res->errno != 0))
370 		return status;
371 	return decode_fhandle(xdr, res);
372 }
373 
374 static int decode_fhs_status(struct xdr_stream *xdr, struct mountres *res)
375 {
376 	unsigned int i;
377 	u32 status;
378 	__be32 *p;
379 
380 	p = xdr_inline_decode(xdr, 4);
381 	if (unlikely(p == NULL))
382 		return -EIO;
383 	status = be32_to_cpup(p);
384 
385 	for (i = 0; i < ARRAY_SIZE(mnt3_errtbl); i++) {
386 		if (mnt3_errtbl[i].status == status) {
387 			res->errno = mnt3_errtbl[i].errno;
388 			return 0;
389 		}
390 	}
391 
392 	dprintk("NFS: unrecognized MNT3 status code: %u\n", status);
393 	res->errno = -EACCES;
394 	return 0;
395 }
396 
397 static int decode_fhandle3(struct xdr_stream *xdr, struct mountres *res)
398 {
399 	struct nfs_fh *fh = res->fh;
400 	u32 size;
401 	__be32 *p;
402 
403 	p = xdr_inline_decode(xdr, 4);
404 	if (unlikely(p == NULL))
405 		return -EIO;
406 
407 	size = be32_to_cpup(p);
408 	if (size > NFS3_FHSIZE || size == 0)
409 		return -EIO;
410 
411 	p = xdr_inline_decode(xdr, size);
412 	if (unlikely(p == NULL))
413 		return -EIO;
414 
415 	fh->size = size;
416 	memcpy(fh->data, p, size);
417 	return 0;
418 }
419 
420 static int decode_auth_flavors(struct xdr_stream *xdr, struct mountres *res)
421 {
422 	rpc_authflavor_t *flavors = res->auth_flavors;
423 	unsigned int *count = res->auth_count;
424 	u32 entries, i;
425 	__be32 *p;
426 
427 	if (*count == 0)
428 		return 0;
429 
430 	p = xdr_inline_decode(xdr, 4);
431 	if (unlikely(p == NULL))
432 		return -EIO;
433 	entries = be32_to_cpup(p);
434 	dprintk("NFS: received %u auth flavors\n", entries);
435 	if (entries > NFS_MAX_SECFLAVORS)
436 		entries = NFS_MAX_SECFLAVORS;
437 
438 	p = xdr_inline_decode(xdr, 4 * entries);
439 	if (unlikely(p == NULL))
440 		return -EIO;
441 
442 	if (entries > *count)
443 		entries = *count;
444 
445 	for (i = 0; i < entries; i++) {
446 		flavors[i] = be32_to_cpup(p++);
447 		dprintk("NFS:   auth flavor[%u]: %d\n", i, flavors[i]);
448 	}
449 	*count = i;
450 
451 	return 0;
452 }
453 
454 static int mnt_xdr_dec_mountres3(struct rpc_rqst *req,
455 				 struct xdr_stream *xdr,
456 				 void *data)
457 {
458 	struct mountres *res = data;
459 	int status;
460 
461 	status = decode_fhs_status(xdr, res);
462 	if (unlikely(status != 0 || res->errno != 0))
463 		return status;
464 	status = decode_fhandle3(xdr, res);
465 	if (unlikely(status != 0)) {
466 		res->errno = -EBADHANDLE;
467 		return 0;
468 	}
469 	return decode_auth_flavors(xdr, res);
470 }
471 
472 static const struct rpc_procinfo mnt_procedures[] = {
473 	[MOUNTPROC_MNT] = {
474 		.p_proc		= MOUNTPROC_MNT,
475 		.p_encode	= mnt_xdr_enc_dirpath,
476 		.p_decode	= mnt_xdr_dec_mountres,
477 		.p_arglen	= MNT_enc_dirpath_sz,
478 		.p_replen	= MNT_dec_mountres_sz,
479 		.p_statidx	= MOUNTPROC_MNT,
480 		.p_name		= "MOUNT",
481 	},
482 	[MOUNTPROC_UMNT] = {
483 		.p_proc		= MOUNTPROC_UMNT,
484 		.p_encode	= mnt_xdr_enc_dirpath,
485 		.p_arglen	= MNT_enc_dirpath_sz,
486 		.p_statidx	= MOUNTPROC_UMNT,
487 		.p_name		= "UMOUNT",
488 	},
489 };
490 
491 static const struct rpc_procinfo mnt3_procedures[] = {
492 	[MOUNTPROC3_MNT] = {
493 		.p_proc		= MOUNTPROC3_MNT,
494 		.p_encode	= mnt_xdr_enc_dirpath,
495 		.p_decode	= mnt_xdr_dec_mountres3,
496 		.p_arglen	= MNT_enc_dirpath_sz,
497 		.p_replen	= MNT_dec_mountres3_sz,
498 		.p_statidx	= MOUNTPROC3_MNT,
499 		.p_name		= "MOUNT",
500 	},
501 	[MOUNTPROC3_UMNT] = {
502 		.p_proc		= MOUNTPROC3_UMNT,
503 		.p_encode	= mnt_xdr_enc_dirpath,
504 		.p_arglen	= MNT_enc_dirpath_sz,
505 		.p_statidx	= MOUNTPROC3_UMNT,
506 		.p_name		= "UMOUNT",
507 	},
508 };
509 
510 static unsigned int mnt_counts[ARRAY_SIZE(mnt_procedures)];
511 static const struct rpc_version mnt_version1 = {
512 	.number		= 1,
513 	.nrprocs	= ARRAY_SIZE(mnt_procedures),
514 	.procs		= mnt_procedures,
515 	.counts		= mnt_counts,
516 };
517 
518 static unsigned int mnt3_counts[ARRAY_SIZE(mnt3_procedures)];
519 static const struct rpc_version mnt_version3 = {
520 	.number		= 3,
521 	.nrprocs	= ARRAY_SIZE(mnt3_procedures),
522 	.procs		= mnt3_procedures,
523 	.counts		= mnt3_counts,
524 };
525 
526 static const struct rpc_version *mnt_version[] = {
527 	NULL,
528 	&mnt_version1,
529 	NULL,
530 	&mnt_version3,
531 };
532 
533 static struct rpc_stat mnt_stats;
534 
535 static const struct rpc_program mnt_program = {
536 	.name		= "mount",
537 	.number		= NFS_MNT_PROGRAM,
538 	.nrvers		= ARRAY_SIZE(mnt_version),
539 	.version	= mnt_version,
540 	.stats		= &mnt_stats,
541 };
542