1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/nfs/nfs4namespace.c
4 *
5 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
6 * - Modified by David Howells <dhowells@redhat.com>
7 *
8 * NFSv4 namespace
9 */
10
11 #include <linux/module.h>
12 #include <linux/dcache.h>
13 #include <linux/mount.h>
14 #include <linux/namei.h>
15 #include <linux/nfs_fs.h>
16 #include <linux/nfs_mount.h>
17 #include <linux/slab.h>
18 #include <linux/string.h>
19 #include <linux/sunrpc/clnt.h>
20 #include <linux/sunrpc/addr.h>
21 #include <linux/vfs.h>
22 #include <linux/inet.h>
23 #include "internal.h"
24 #include "nfs4_fs.h"
25 #include "nfs.h"
26 #include "dns_resolve.h"
27
28 #define NFSDBG_FACILITY NFSDBG_VFS
29
30 /*
31 * Work out the length that an NFSv4 path would render to as a standard posix
32 * path, with a leading slash but no terminating slash.
33 */
34 static ssize_t nfs4_pathname_len(const struct nfs4_pathname *pathname)
35 {
36 ssize_t len = 0;
37 int i;
38
39 for (i = 0; i < pathname->ncomponents; i++) {
40 const struct nfs4_string *component = &pathname->components[i];
41
42 if (component->len > NAME_MAX)
43 goto too_long;
44 len += 1 + component->len; /* Adding "/foo" */
45 if (len > PATH_MAX)
46 goto too_long;
47 }
48 return len;
49
50 too_long:
51 return -ENAMETOOLONG;
52 }
53
54 /*
55 * Convert the NFSv4 pathname components into a standard posix path.
56 */
57 static char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
58 unsigned short *_len)
59 {
60 ssize_t len;
61 char *buf, *p;
62 int i;
63
64 len = nfs4_pathname_len(pathname);
65 if (len < 0)
66 return ERR_PTR(len);
67 *_len = len;
68
69 p = buf = kmalloc(len + 1, GFP_KERNEL);
70 if (!buf)
71 return ERR_PTR(-ENOMEM);
72
73 for (i = 0; i < pathname->ncomponents; i++) {
74 const struct nfs4_string *component = &pathname->components[i];
75
76 *p++ = '/';
77 memcpy(p, component->data, component->len);
78 p += component->len;
79 }
80
81 *p = 0;
82 return buf;
83 }
84
85 /*
86 * return the path component of "<server>:<path>"
87 * nfspath - the "<server>:<path>" string
88 * end - one past the last char that could contain "<server>:"
89 * returns NULL on failure
90 */
91 static char *nfs_path_component(const char *nfspath, const char *end)
92 {
93 char *p;
94
95 if (*nfspath == '[') {
96 /* parse [] escaped IPv6 addrs */
97 p = strchr(nfspath, ']');
98 if (p != NULL && ++p < end && *p == ':')
99 return p + 1;
100 } else {
101 /* otherwise split on first colon */
102 p = strchr(nfspath, ':');
103 if (p != NULL && p < end)
104 return p + 1;
105 }
106 return NULL;
107 }
108
109 /*
110 * Determine the mount path as a string
111 */
112 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
113 {
114 char *limit;
115 char *path = nfs_path(&limit, dentry, buffer, buflen,
116 NFS_PATH_CANONICAL);
117 if (!IS_ERR(path)) {
118 char *path_component = nfs_path_component(path, limit);
119 if (path_component)
120 return path_component;
121 }
122 return path;
123 }
124
125 /*
126 * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
127 * believe to be the server path to this dentry
128 */
129 static int nfs4_validate_fspath(struct dentry *dentry,
130 const struct nfs4_fs_locations *locations,
131 struct nfs_fs_context *ctx)
132 {
133 const char *path;
134 char *fs_path;
135 unsigned short len;
136 char *buf;
137 int n;
138
139 buf = kmalloc(4096, GFP_KERNEL);
140 if (!buf)
141 return -ENOMEM;
142
143 path = nfs4_path(dentry, buf, 4096);
144 if (IS_ERR(path)) {
145 kfree(buf);
146 return PTR_ERR(path);
147 }
148
149 fs_path = nfs4_pathname_string(&locations->fs_path, &len);
150 if (IS_ERR(fs_path)) {
151 kfree(buf);
152 return PTR_ERR(fs_path);
153 }
154
155 n = strncmp(path, fs_path, len);
156 kfree(buf);
157 kfree(fs_path);
158 if (n != 0) {
159 dprintk("%s: path %s does not begin with fsroot %s\n",
160 __func__, path, ctx->nfs_server.export_path);
161 return -ENOENT;
162 }
163
164 return 0;
165 }
166
167 size_t nfs_parse_server_name(char *string, size_t len, struct sockaddr_storage *ss,
168 size_t salen, struct net *net, int port)
169 {
170 struct sockaddr *sa = (struct sockaddr *)ss;
171 ssize_t ret;
172
173 ret = rpc_pton(net, string, len, sa, salen);
174 if (ret == 0) {
175 ret = rpc_uaddr2sockaddr(net, string, len, sa, salen);
176 if (ret == 0) {
177 ret = nfs_dns_resolve_name(net, string, len, ss, salen);
178 if (ret < 0)
179 ret = 0;
180 }
181 } else if (port) {
182 rpc_set_port(sa, port);
183 }
184 return ret;
185 }
186
187 /**
188 * nfs_find_best_sec - Find a security mechanism supported locally
189 * @clnt: pointer to rpc_clnt
190 * @server: NFS server struct
191 * @flavors: List of security tuples returned by SECINFO procedure
192 *
193 * Return an rpc client that uses the first security mechanism in
194 * "flavors" that is locally supported. The "flavors" array
195 * is searched in the order returned from the server, per RFC 3530
196 * recommendation and each flavor is checked for membership in the
197 * sec= mount option list if it exists.
198 *
199 * Return -EPERM if no matching flavor is found in the array.
200 *
201 * Please call rpc_shutdown_client() when you are done with this rpc client.
202 *
203 */
204 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
205 struct nfs_server *server,
206 struct nfs4_secinfo_flavors *flavors)
207 {
208 rpc_authflavor_t pflavor;
209 struct nfs4_secinfo4 *secinfo;
210 unsigned int i;
211
212 for (i = 0; i < flavors->num_flavors; i++) {
213 secinfo = &flavors->flavors[i];
214
215 switch (secinfo->flavor) {
216 case RPC_AUTH_NULL:
217 case RPC_AUTH_UNIX:
218 case RPC_AUTH_GSS:
219 pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
220 &secinfo->flavor_info);
221 /* does the pseudoflavor match a sec= mount opt? */
222 if (pflavor != RPC_AUTH_MAXFLAVOR &&
223 nfs_auth_info_match(&server->auth_info, pflavor)) {
224 struct rpc_clnt *new;
225 struct rpc_cred *cred;
226
227 /* Cloning creates an rpc_auth for the flavor */
228 new = rpc_clone_client_set_auth(clnt, pflavor);
229 if (IS_ERR(new))
230 continue;
231 /**
232 * Check that the user actually can use the
233 * flavor. This is mostly for RPC_AUTH_GSS
234 * where cr_init obtains a gss context
235 */
236 cred = rpcauth_lookupcred(new->cl_auth, 0);
237 if (IS_ERR(cred)) {
238 rpc_shutdown_client(new);
239 continue;
240 }
241 put_rpccred(cred);
242 return new;
243 }
244 }
245 }
246 return ERR_PTR(-EPERM);
247 }
248
249 /**
250 * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
251 * return an rpc_clnt that uses the best available security flavor with
252 * respect to the secinfo flavor list and the sec= mount options.
253 *
254 * @clnt: RPC client to clone
255 * @inode: directory inode
256 * @name: lookup name
257 *
258 * Please call rpc_shutdown_client() when you are done with this rpc client.
259 */
260 struct rpc_clnt *
261 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
262 const struct qstr *name)
263 {
264 struct page *page;
265 struct nfs4_secinfo_flavors *flavors;
266 struct rpc_clnt *new;
267 int err;
268
269 page = alloc_page(GFP_KERNEL);
270 if (!page)
271 return ERR_PTR(-ENOMEM);
272
273 flavors = page_address(page);
274
275 err = nfs4_proc_secinfo(inode, name, flavors);
276 if (err < 0) {
277 new = ERR_PTR(err);
278 goto out;
279 }
280
281 new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
282
283 out:
284 put_page(page);
285 return new;
286 }
287
288 static int try_location(struct fs_context *fc,
289 const struct nfs4_fs_location *location)
290 {
291 struct nfs_fs_context *ctx = nfs_fc2context(fc);
292 unsigned int len, s;
293 char *export_path, *source, *p;
294 int ret = -ENOENT;
295
296 /* Allocate a buffer big enough to hold any of the hostnames plus a
297 * terminating char and also a buffer big enough to hold the hostname
298 * plus a colon plus the path.
299 */
300 len = 0;
301 for (s = 0; s < location->nservers; s++) {
302 const struct nfs4_string *buf = &location->servers[s];
303 if (buf->len > len)
304 len = buf->len;
305 }
306
307 kfree(ctx->nfs_server.hostname);
308 ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL);
309 if (!ctx->nfs_server.hostname)
310 return -ENOMEM;
311
312 export_path = nfs4_pathname_string(&location->rootpath,
313 &ctx->nfs_server.export_path_len);
314 if (IS_ERR(export_path))
315 return PTR_ERR(export_path);
316
317 kfree(ctx->nfs_server.export_path);
318 ctx->nfs_server.export_path = export_path;
319
320 source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1,
321 GFP_KERNEL);
322 if (!source)
323 return -ENOMEM;
324
325 kfree(fc->source);
326 fc->source = source;
327 for (s = 0; s < location->nservers; s++) {
328 const struct nfs4_string *buf = &location->servers[s];
329
330 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
331 continue;
332
333 ctx->nfs_server.addrlen =
334 nfs_parse_server_name(buf->data, buf->len,
335 &ctx->nfs_server._address,
336 sizeof(ctx->nfs_server._address),
337 fc->net_ns, 0);
338 if (ctx->nfs_server.addrlen == 0)
339 continue;
340
341 rpc_set_port(&ctx->nfs_server.address, NFS_PORT);
342
343 memcpy(ctx->nfs_server.hostname, buf->data, buf->len);
344 ctx->nfs_server.hostname[buf->len] = '\0';
345
346 p = source;
347 memcpy(p, buf->data, buf->len);
348 p += buf->len;
349 *p++ = ':';
350 memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len);
351 p += ctx->nfs_server.export_path_len;
352 *p = 0;
353
354 ret = nfs4_get_referral_tree(fc);
355 if (ret == 0)
356 return 0;
357 }
358
359 return ret;
360 }
361
362 /**
363 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
364 * @fc: pointer to struct nfs_fs_context
365 * @locations: array of NFSv4 server location information
366 *
367 */
368 static int nfs_follow_referral(struct fs_context *fc,
369 const struct nfs4_fs_locations *locations)
370 {
371 struct nfs_fs_context *ctx = nfs_fc2context(fc);
372 int loc, error;
373
374 if (locations == NULL || locations->nlocations <= 0)
375 return -ENOENT;
376
377 dprintk("%s: referral at %pd2\n", __func__, ctx->clone_data.dentry);
378
379 /* Ensure fs path is a prefix of current dentry path */
380 error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx);
381 if (error < 0)
382 return error;
383
384 error = -ENOENT;
385 for (loc = 0; loc < locations->nlocations; loc++) {
386 const struct nfs4_fs_location *location = &locations->locations[loc];
387
388 if (location == NULL || location->nservers <= 0 ||
389 location->rootpath.ncomponents == 0)
390 continue;
391
392 error = try_location(fc, location);
393 if (error == 0)
394 return 0;
395 }
396
397 return error;
398 }
399
400 /*
401 * nfs_do_refmount - handle crossing a referral on server
402 * @dentry - dentry of referral
403 *
404 */
405 static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client)
406 {
407 struct nfs_fs_context *ctx = nfs_fc2context(fc);
408 struct dentry *dentry, *parent;
409 struct nfs4_fs_locations *fs_locations = NULL;
410 struct page *page;
411 int err = -ENOMEM;
412
413 /* BUG_ON(IS_ROOT(dentry)); */
414 page = alloc_page(GFP_KERNEL);
415 if (!page)
416 return -ENOMEM;
417
418 fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
419 if (!fs_locations)
420 goto out_free;
421 fs_locations->fattr = nfs_alloc_fattr();
422 if (!fs_locations->fattr)
423 goto out_free_2;
424
425 /* Get locations */
426 dentry = ctx->clone_data.dentry;
427 parent = dget_parent(dentry);
428 dprintk("%s: getting locations for %pd2\n",
429 __func__, dentry);
430
431 err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
432 dput(parent);
433 if (err != 0)
434 goto out_free_3;
435
436 err = -ENOENT;
437 if (fs_locations->nlocations <= 0 ||
438 fs_locations->fs_path.ncomponents <= 0)
439 goto out_free_3;
440
441 err = nfs_follow_referral(fc, fs_locations);
442 out_free_3:
443 kfree(fs_locations->fattr);
444 out_free_2:
445 kfree(fs_locations);
446 out_free:
447 __free_page(page);
448 return err;
449 }
450
451 int nfs4_submount(struct fs_context *fc, struct nfs_server *server)
452 {
453 struct nfs_fs_context *ctx = nfs_fc2context(fc);
454 struct dentry *dentry = ctx->clone_data.dentry;
455 struct dentry *parent = dget_parent(dentry);
456 struct inode *dir = d_inode(parent);
457 struct rpc_clnt *client;
458 int ret;
459
460 /* Look it up again to get its attributes and sec flavor */
461 client = nfs4_proc_lookup_mountpoint(dir, dentry, ctx->mntfh,
462 ctx->clone_data.fattr);
463 dput(parent);
464 if (IS_ERR(client))
465 return PTR_ERR(client);
466
467 ctx->selected_flavor = client->cl_auth->au_flavor;
468 if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
469 ret = nfs_do_refmount(fc, client);
470 } else {
471 ret = nfs_do_submount(fc);
472 }
473
474 rpc_shutdown_client(client);
475 return ret;
476 }
477
478 /*
479 * Try one location from the fs_locations array.
480 *
481 * Returns zero on success, or a negative errno value.
482 */
483 static int nfs4_try_replacing_one_location(struct nfs_server *server,
484 char *page, char *page2,
485 const struct nfs4_fs_location *location)
486 {
487 struct net *net = rpc_net_ns(server->client);
488 struct sockaddr_storage *sap;
489 unsigned int s;
490 size_t salen;
491 int error;
492
493 sap = kmalloc(sizeof(*sap), GFP_KERNEL);
494 if (sap == NULL)
495 return -ENOMEM;
496
497 error = -ENOENT;
498 for (s = 0; s < location->nservers; s++) {
499 const struct nfs4_string *buf = &location->servers[s];
500 char *hostname;
501
502 if (buf->len <= 0 || buf->len > PAGE_SIZE)
503 continue;
504
505 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
506 continue;
507
508 salen = nfs_parse_server_name(buf->data, buf->len,
509 sap, sizeof(*sap), net, 0);
510 if (salen == 0)
511 continue;
512 rpc_set_port((struct sockaddr *)sap, NFS_PORT);
513
514 error = -ENOMEM;
515 hostname = kmemdup_nul(buf->data, buf->len, GFP_KERNEL);
516 if (hostname == NULL)
517 break;
518
519 error = nfs4_update_server(server, hostname, sap, salen, net);
520 kfree(hostname);
521 if (error == 0)
522 break;
523 }
524
525 kfree(sap);
526 return error;
527 }
528
529 /**
530 * nfs4_replace_transport - set up transport to destination server
531 *
532 * @server: export being migrated
533 * @locations: fs_locations array
534 *
535 * Returns zero on success, or a negative errno value.
536 *
537 * The client tries all the entries in the "locations" array, in the
538 * order returned by the server, until one works or the end of the
539 * array is reached.
540 */
541 int nfs4_replace_transport(struct nfs_server *server,
542 const struct nfs4_fs_locations *locations)
543 {
544 char *page = NULL, *page2 = NULL;
545 int loc, error;
546
547 error = -ENOENT;
548 if (locations == NULL || locations->nlocations <= 0)
549 goto out;
550
551 error = -ENOMEM;
552 page = (char *) __get_free_page(GFP_USER);
553 if (!page)
554 goto out;
555 page2 = (char *) __get_free_page(GFP_USER);
556 if (!page2)
557 goto out;
558
559 for (loc = 0; loc < locations->nlocations; loc++) {
560 const struct nfs4_fs_location *location =
561 &locations->locations[loc];
562
563 if (location == NULL || location->nservers <= 0 ||
564 location->rootpath.ncomponents == 0)
565 continue;
566
567 error = nfs4_try_replacing_one_location(server, page,
568 page2, location);
569 if (error == 0)
570 break;
571 }
572
573 out:
574 free_page((unsigned long)page);
575 free_page((unsigned long)page2);
576 return error;
577 }
578
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