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(error: len); |
67 | *_len = len; |
68 | |
69 | p = buf = kmalloc(size: len + 1, GFP_KERNEL); |
70 | if (!buf) |
71 | return ERR_PTR(error: -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(p: &limit, dentry, buffer, buflen, |
116 | NFS_PATH_CANONICAL); |
117 | if (!IS_ERR(ptr: path)) { |
118 | char *path_component = nfs_path_component(nfspath: path, end: 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(size: 4096, GFP_KERNEL); |
140 | if (!buf) |
141 | return -ENOMEM; |
142 | |
143 | path = nfs4_path(dentry, buffer: buf, buflen: 4096); |
144 | if (IS_ERR(ptr: path)) { |
145 | kfree(objp: buf); |
146 | return PTR_ERR(ptr: path); |
147 | } |
148 | |
149 | fs_path = nfs4_pathname_string(pathname: &locations->fs_path, len: &len); |
150 | if (IS_ERR(ptr: fs_path)) { |
151 | kfree(objp: buf); |
152 | return PTR_ERR(ptr: fs_path); |
153 | } |
154 | |
155 | n = strncmp(path, fs_path, len); |
156 | kfree(objp: buf); |
157 | kfree(objp: 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, name: string, namelen: len, sa: ss, salen); |
178 | if (ret < 0) |
179 | ret = 0; |
180 | } |
181 | } else if (port) { |
182 | rpc_set_port(sap: 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(ptr: 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(ptr: cred)) { |
238 | rpc_shutdown_client(new); |
239 | continue; |
240 | } |
241 | put_rpccred(cred); |
242 | return new; |
243 | } |
244 | } |
245 | } |
246 | return ERR_PTR(error: -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(error: -ENOMEM); |
272 | |
273 | flavors = page_address(page); |
274 | |
275 | err = nfs4_proc_secinfo(inode, name, flavors); |
276 | if (err < 0) { |
277 | new = ERR_PTR(error: err); |
278 | goto out; |
279 | } |
280 | |
281 | new = nfs_find_best_sec(clnt, server: 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(objp: ctx->nfs_server.hostname); |
308 | ctx->nfs_server.hostname = kmalloc(size: len + 1, GFP_KERNEL); |
309 | if (!ctx->nfs_server.hostname) |
310 | return -ENOMEM; |
311 | |
312 | export_path = nfs4_pathname_string(pathname: &location->rootpath, |
313 | len: &ctx->nfs_server.export_path_len); |
314 | if (IS_ERR(ptr: export_path)) |
315 | return PTR_ERR(ptr: export_path); |
316 | |
317 | kfree(objp: ctx->nfs_server.export_path); |
318 | ctx->nfs_server.export_path = export_path; |
319 | |
320 | source = kmalloc(size: len + 1 + ctx->nfs_server.export_path_len + 1, |
321 | GFP_KERNEL); |
322 | if (!source) |
323 | return -ENOMEM; |
324 | |
325 | kfree(objp: 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(p: buf->data, IPV6_SCOPE_DELIMITER, size: buf->len)) |
331 | continue; |
332 | |
333 | ctx->nfs_server.addrlen = |
334 | nfs_parse_server_name(string: buf->data, len: buf->len, |
335 | ss: &ctx->nfs_server._address, |
336 | salen: sizeof(ctx->nfs_server._address), |
337 | net: fc->net_ns, port: 0); |
338 | if (ctx->nfs_server.addrlen == 0) |
339 | continue; |
340 | |
341 | rpc_set_port(sap: &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(dentry: 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(size: 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(dentry: 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, locations: fs_locations); |
442 | out_free_3: |
443 | kfree(objp: fs_locations->fattr); |
444 | out_free_2: |
445 | kfree(objp: 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(dentry: 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(ptr: client)) |
465 | return PTR_ERR(ptr: 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(size: 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(p: buf->data, IPV6_SCOPE_DELIMITER, size: buf->len) != NULL) |
506 | continue; |
507 | |
508 | salen = nfs_parse_server_name(string: buf->data, len: buf->len, |
509 | ss: sap, salen: sizeof(*sap), net, port: 0); |
510 | if (salen == 0) |
511 | continue; |
512 | rpc_set_port(sap: (struct sockaddr *)sap, NFS_PORT); |
513 | |
514 | error = -ENOMEM; |
515 | hostname = kmemdup_nul(s: buf->data, len: buf->len, GFP_KERNEL); |
516 | if (hostname == NULL) |
517 | break; |
518 | |
519 | error = nfs4_update_server(server, hostname, sap, salen, net); |
520 | kfree(objp: hostname); |
521 | if (error == 0) |
522 | break; |
523 | } |
524 | |
525 | kfree(objp: 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 | |