1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * linux/fs/nfs/dns_resolve.c |
4 | * |
5 | * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com> |
6 | * |
7 | * Resolves DNS hostnames into valid ip addresses |
8 | */ |
9 | |
10 | #include <linux/module.h> |
11 | #include <linux/sunrpc/clnt.h> |
12 | #include <linux/sunrpc/addr.h> |
13 | |
14 | #include "dns_resolve.h" |
15 | |
16 | #ifdef CONFIG_NFS_USE_KERNEL_DNS |
17 | |
18 | #include <linux/dns_resolver.h> |
19 | |
20 | ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen, |
21 | struct sockaddr_storage *ss, size_t salen) |
22 | { |
23 | struct sockaddr *sa = (struct sockaddr *)ss; |
24 | ssize_t ret; |
25 | char *ip_addr = NULL; |
26 | int ip_len; |
27 | |
28 | ip_len = dns_query(net, NULL, name, namelen, NULL, &ip_addr, NULL, |
29 | false); |
30 | if (ip_len > 0) |
31 | ret = rpc_pton(net, ip_addr, ip_len, sa, salen); |
32 | else |
33 | ret = -ESRCH; |
34 | kfree(ip_addr); |
35 | return ret; |
36 | } |
37 | |
38 | #else |
39 | |
40 | #include <linux/hash.h> |
41 | #include <linux/string.h> |
42 | #include <linux/kmod.h> |
43 | #include <linux/slab.h> |
44 | #include <linux/socket.h> |
45 | #include <linux/seq_file.h> |
46 | #include <linux/inet.h> |
47 | #include <linux/sunrpc/cache.h> |
48 | #include <linux/sunrpc/svcauth.h> |
49 | #include <linux/sunrpc/rpc_pipe_fs.h> |
50 | #include <linux/nfs_fs.h> |
51 | |
52 | #include "nfs4_fs.h" |
53 | #include "cache_lib.h" |
54 | #include "netns.h" |
55 | |
56 | #define NFS_DNS_HASHBITS 4 |
57 | #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS) |
58 | |
59 | struct nfs_dns_ent { |
60 | struct cache_head h; |
61 | |
62 | char *hostname; |
63 | size_t namelen; |
64 | |
65 | struct sockaddr_storage addr; |
66 | size_t addrlen; |
67 | struct rcu_head rcu_head; |
68 | }; |
69 | |
70 | |
71 | static void nfs_dns_ent_update(struct cache_head *cnew, |
72 | struct cache_head *ckey) |
73 | { |
74 | struct nfs_dns_ent *new; |
75 | struct nfs_dns_ent *key; |
76 | |
77 | new = container_of(cnew, struct nfs_dns_ent, h); |
78 | key = container_of(ckey, struct nfs_dns_ent, h); |
79 | |
80 | memcpy(&new->addr, &key->addr, key->addrlen); |
81 | new->addrlen = key->addrlen; |
82 | } |
83 | |
84 | static void nfs_dns_ent_init(struct cache_head *cnew, |
85 | struct cache_head *ckey) |
86 | { |
87 | struct nfs_dns_ent *new; |
88 | struct nfs_dns_ent *key; |
89 | |
90 | new = container_of(cnew, struct nfs_dns_ent, h); |
91 | key = container_of(ckey, struct nfs_dns_ent, h); |
92 | |
93 | kfree(objp: new->hostname); |
94 | new->hostname = kmemdup_nul(s: key->hostname, len: key->namelen, GFP_KERNEL); |
95 | if (new->hostname) { |
96 | new->namelen = key->namelen; |
97 | nfs_dns_ent_update(cnew, ckey); |
98 | } else { |
99 | new->namelen = 0; |
100 | new->addrlen = 0; |
101 | } |
102 | } |
103 | |
104 | static void nfs_dns_ent_free_rcu(struct rcu_head *head) |
105 | { |
106 | struct nfs_dns_ent *item; |
107 | |
108 | item = container_of(head, struct nfs_dns_ent, rcu_head); |
109 | kfree(objp: item->hostname); |
110 | kfree(objp: item); |
111 | } |
112 | |
113 | static void nfs_dns_ent_put(struct kref *ref) |
114 | { |
115 | struct nfs_dns_ent *item; |
116 | |
117 | item = container_of(ref, struct nfs_dns_ent, h.ref); |
118 | call_rcu(head: &item->rcu_head, func: nfs_dns_ent_free_rcu); |
119 | } |
120 | |
121 | static struct cache_head *nfs_dns_ent_alloc(void) |
122 | { |
123 | struct nfs_dns_ent *item = kmalloc(size: sizeof(*item), GFP_KERNEL); |
124 | |
125 | if (item != NULL) { |
126 | item->hostname = NULL; |
127 | item->namelen = 0; |
128 | item->addrlen = 0; |
129 | return &item->h; |
130 | } |
131 | return NULL; |
132 | }; |
133 | |
134 | static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key) |
135 | { |
136 | return hash_str(name: key->hostname, NFS_DNS_HASHBITS); |
137 | } |
138 | |
139 | static void nfs_dns_request(struct cache_detail *cd, |
140 | struct cache_head *ch, |
141 | char **bpp, int *blen) |
142 | { |
143 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); |
144 | |
145 | qword_add(bpp, lp: blen, str: key->hostname); |
146 | (*bpp)[-1] = '\n'; |
147 | } |
148 | |
149 | static int nfs_dns_upcall(struct cache_detail *cd, |
150 | struct cache_head *ch) |
151 | { |
152 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); |
153 | |
154 | if (test_and_set_bit(nr: CACHE_PENDING, addr: &ch->flags)) |
155 | return 0; |
156 | if (!nfs_cache_upcall(cd, entry_name: key->hostname)) |
157 | return 0; |
158 | clear_bit(nr: CACHE_PENDING, addr: &ch->flags); |
159 | return sunrpc_cache_pipe_upcall_timeout(detail: cd, h: ch); |
160 | } |
161 | |
162 | static int nfs_dns_match(struct cache_head *ca, |
163 | struct cache_head *cb) |
164 | { |
165 | struct nfs_dns_ent *a; |
166 | struct nfs_dns_ent *b; |
167 | |
168 | a = container_of(ca, struct nfs_dns_ent, h); |
169 | b = container_of(cb, struct nfs_dns_ent, h); |
170 | |
171 | if (a->namelen == 0 || a->namelen != b->namelen) |
172 | return 0; |
173 | return memcmp(p: a->hostname, q: b->hostname, size: a->namelen) == 0; |
174 | } |
175 | |
176 | static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd, |
177 | struct cache_head *h) |
178 | { |
179 | struct nfs_dns_ent *item; |
180 | long ttl; |
181 | |
182 | if (h == NULL) { |
183 | seq_puts(m, s: "# ip address hostname ttl\n" ); |
184 | return 0; |
185 | } |
186 | item = container_of(h, struct nfs_dns_ent, h); |
187 | ttl = item->h.expiry_time - seconds_since_boot(); |
188 | if (ttl < 0) |
189 | ttl = 0; |
190 | |
191 | if (!test_bit(CACHE_NEGATIVE, &h->flags)) { |
192 | char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1]; |
193 | |
194 | rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf)); |
195 | seq_printf(m, fmt: "%15s " , buf); |
196 | } else |
197 | seq_puts(m, s: "<none> " ); |
198 | seq_printf(m, fmt: "%15s %ld\n" , item->hostname, ttl); |
199 | return 0; |
200 | } |
201 | |
202 | static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd, |
203 | struct nfs_dns_ent *key) |
204 | { |
205 | struct cache_head *ch; |
206 | |
207 | ch = sunrpc_cache_lookup_rcu(detail: cd, |
208 | key: &key->h, |
209 | hash: nfs_dns_hash(key)); |
210 | if (!ch) |
211 | return NULL; |
212 | return container_of(ch, struct nfs_dns_ent, h); |
213 | } |
214 | |
215 | static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd, |
216 | struct nfs_dns_ent *new, |
217 | struct nfs_dns_ent *key) |
218 | { |
219 | struct cache_head *ch; |
220 | |
221 | ch = sunrpc_cache_update(detail: cd, |
222 | new: &new->h, old: &key->h, |
223 | hash: nfs_dns_hash(key)); |
224 | if (!ch) |
225 | return NULL; |
226 | return container_of(ch, struct nfs_dns_ent, h); |
227 | } |
228 | |
229 | static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen) |
230 | { |
231 | char buf1[NFS_DNS_HOSTNAME_MAXLEN+1]; |
232 | struct nfs_dns_ent key, *item; |
233 | unsigned int ttl; |
234 | ssize_t len; |
235 | int ret = -EINVAL; |
236 | |
237 | if (buf[buflen-1] != '\n') |
238 | goto out; |
239 | buf[buflen-1] = '\0'; |
240 | |
241 | len = qword_get(bpp: &buf, dest: buf1, bufsize: sizeof(buf1)); |
242 | if (len <= 0) |
243 | goto out; |
244 | key.addrlen = rpc_pton(cd->net, buf1, len, |
245 | (struct sockaddr *)&key.addr, |
246 | sizeof(key.addr)); |
247 | |
248 | len = qword_get(bpp: &buf, dest: buf1, bufsize: sizeof(buf1)); |
249 | if (len <= 0) |
250 | goto out; |
251 | |
252 | key.hostname = buf1; |
253 | key.namelen = len; |
254 | memset(&key.h, 0, sizeof(key.h)); |
255 | |
256 | if (get_uint(bpp: &buf, anint: &ttl) < 0) |
257 | goto out; |
258 | if (ttl == 0) |
259 | goto out; |
260 | key.h.expiry_time = ttl + seconds_since_boot(); |
261 | |
262 | ret = -ENOMEM; |
263 | item = nfs_dns_lookup(cd, key: &key); |
264 | if (item == NULL) |
265 | goto out; |
266 | |
267 | if (key.addrlen == 0) |
268 | set_bit(nr: CACHE_NEGATIVE, addr: &key.h.flags); |
269 | |
270 | item = nfs_dns_update(cd, new: &key, key: item); |
271 | if (item == NULL) |
272 | goto out; |
273 | |
274 | ret = 0; |
275 | cache_put(h: &item->h, cd); |
276 | out: |
277 | return ret; |
278 | } |
279 | |
280 | static int do_cache_lookup(struct cache_detail *cd, |
281 | struct nfs_dns_ent *key, |
282 | struct nfs_dns_ent **item, |
283 | struct nfs_cache_defer_req *dreq) |
284 | { |
285 | int ret = -ENOMEM; |
286 | |
287 | *item = nfs_dns_lookup(cd, key); |
288 | if (*item) { |
289 | ret = cache_check(detail: cd, h: &(*item)->h, rqstp: &dreq->req); |
290 | if (ret) |
291 | *item = NULL; |
292 | } |
293 | return ret; |
294 | } |
295 | |
296 | static int do_cache_lookup_nowait(struct cache_detail *cd, |
297 | struct nfs_dns_ent *key, |
298 | struct nfs_dns_ent **item) |
299 | { |
300 | int ret = -ENOMEM; |
301 | |
302 | *item = nfs_dns_lookup(cd, key); |
303 | if (!*item) |
304 | goto out_err; |
305 | ret = -ETIMEDOUT; |
306 | if (!test_bit(CACHE_VALID, &(*item)->h.flags) |
307 | || (*item)->h.expiry_time < seconds_since_boot() |
308 | || cd->flush_time > (*item)->h.last_refresh) |
309 | goto out_put; |
310 | ret = -ENOENT; |
311 | if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags)) |
312 | goto out_put; |
313 | return 0; |
314 | out_put: |
315 | cache_put(h: &(*item)->h, cd); |
316 | out_err: |
317 | *item = NULL; |
318 | return ret; |
319 | } |
320 | |
321 | static int do_cache_lookup_wait(struct cache_detail *cd, |
322 | struct nfs_dns_ent *key, |
323 | struct nfs_dns_ent **item) |
324 | { |
325 | struct nfs_cache_defer_req *dreq; |
326 | int ret = -ENOMEM; |
327 | |
328 | dreq = nfs_cache_defer_req_alloc(); |
329 | if (!dreq) |
330 | goto out; |
331 | ret = do_cache_lookup(cd, key, item, dreq); |
332 | if (ret == -EAGAIN) { |
333 | ret = nfs_cache_wait_for_upcall(dreq); |
334 | if (!ret) |
335 | ret = do_cache_lookup_nowait(cd, key, item); |
336 | } |
337 | nfs_cache_defer_req_put(dreq); |
338 | out: |
339 | return ret; |
340 | } |
341 | |
342 | ssize_t nfs_dns_resolve_name(struct net *net, char *name, |
343 | size_t namelen, struct sockaddr_storage *ss, size_t salen) |
344 | { |
345 | struct nfs_dns_ent key = { |
346 | .hostname = name, |
347 | .namelen = namelen, |
348 | }; |
349 | struct nfs_dns_ent *item = NULL; |
350 | ssize_t ret; |
351 | struct nfs_net *nn = net_generic(net, id: nfs_net_id); |
352 | |
353 | ret = do_cache_lookup_wait(cd: nn->nfs_dns_resolve, key: &key, item: &item); |
354 | if (ret == 0) { |
355 | if (salen >= item->addrlen) { |
356 | memcpy(ss, &item->addr, item->addrlen); |
357 | ret = item->addrlen; |
358 | } else |
359 | ret = -EOVERFLOW; |
360 | cache_put(h: &item->h, cd: nn->nfs_dns_resolve); |
361 | } else if (ret == -ENOENT) |
362 | ret = -ESRCH; |
363 | return ret; |
364 | } |
365 | |
366 | static struct cache_detail nfs_dns_resolve_template = { |
367 | .owner = THIS_MODULE, |
368 | .hash_size = NFS_DNS_HASHTBL_SIZE, |
369 | .name = "dns_resolve" , |
370 | .cache_put = nfs_dns_ent_put, |
371 | .cache_upcall = nfs_dns_upcall, |
372 | .cache_request = nfs_dns_request, |
373 | .cache_parse = nfs_dns_parse, |
374 | .cache_show = nfs_dns_show, |
375 | .match = nfs_dns_match, |
376 | .init = nfs_dns_ent_init, |
377 | .update = nfs_dns_ent_update, |
378 | .alloc = nfs_dns_ent_alloc, |
379 | }; |
380 | |
381 | |
382 | int nfs_dns_resolver_cache_init(struct net *net) |
383 | { |
384 | int err; |
385 | struct nfs_net *nn = net_generic(net, id: nfs_net_id); |
386 | |
387 | nn->nfs_dns_resolve = cache_create_net(tmpl: &nfs_dns_resolve_template, net); |
388 | if (IS_ERR(ptr: nn->nfs_dns_resolve)) |
389 | return PTR_ERR(ptr: nn->nfs_dns_resolve); |
390 | |
391 | err = nfs_cache_register_net(net, cd: nn->nfs_dns_resolve); |
392 | if (err) |
393 | goto err_reg; |
394 | return 0; |
395 | |
396 | err_reg: |
397 | cache_destroy_net(cd: nn->nfs_dns_resolve, net); |
398 | return err; |
399 | } |
400 | |
401 | void nfs_dns_resolver_cache_destroy(struct net *net) |
402 | { |
403 | struct nfs_net *nn = net_generic(net, id: nfs_net_id); |
404 | |
405 | nfs_cache_unregister_net(net, cd: nn->nfs_dns_resolve); |
406 | cache_destroy_net(cd: nn->nfs_dns_resolve, net); |
407 | } |
408 | |
409 | static int nfs4_dns_net_init(struct net *net) |
410 | { |
411 | return nfs_dns_resolver_cache_init(net); |
412 | } |
413 | |
414 | static void nfs4_dns_net_exit(struct net *net) |
415 | { |
416 | nfs_dns_resolver_cache_destroy(net); |
417 | } |
418 | |
419 | static struct pernet_operations nfs4_dns_resolver_ops = { |
420 | .init = nfs4_dns_net_init, |
421 | .exit = nfs4_dns_net_exit, |
422 | }; |
423 | |
424 | static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event, |
425 | void *ptr) |
426 | { |
427 | struct super_block *sb = ptr; |
428 | struct net *net = sb->s_fs_info; |
429 | struct nfs_net *nn = net_generic(net, id: nfs_net_id); |
430 | struct cache_detail *cd = nn->nfs_dns_resolve; |
431 | int ret = 0; |
432 | |
433 | if (cd == NULL) |
434 | return 0; |
435 | |
436 | if (!try_module_get(THIS_MODULE)) |
437 | return 0; |
438 | |
439 | switch (event) { |
440 | case RPC_PIPEFS_MOUNT: |
441 | ret = nfs_cache_register_sb(sb, cd); |
442 | break; |
443 | case RPC_PIPEFS_UMOUNT: |
444 | nfs_cache_unregister_sb(sb, cd); |
445 | break; |
446 | default: |
447 | ret = -ENOTSUPP; |
448 | break; |
449 | } |
450 | module_put(THIS_MODULE); |
451 | return ret; |
452 | } |
453 | |
454 | static struct notifier_block nfs_dns_resolver_block = { |
455 | .notifier_call = rpc_pipefs_event, |
456 | }; |
457 | |
458 | int nfs_dns_resolver_init(void) |
459 | { |
460 | int err; |
461 | |
462 | err = register_pernet_subsys(&nfs4_dns_resolver_ops); |
463 | if (err < 0) |
464 | goto out; |
465 | err = rpc_pipefs_notifier_register(&nfs_dns_resolver_block); |
466 | if (err < 0) |
467 | goto out1; |
468 | return 0; |
469 | out1: |
470 | unregister_pernet_subsys(&nfs4_dns_resolver_ops); |
471 | out: |
472 | return err; |
473 | } |
474 | |
475 | void nfs_dns_resolver_destroy(void) |
476 | { |
477 | rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block); |
478 | unregister_pernet_subsys(&nfs4_dns_resolver_ops); |
479 | } |
480 | #endif |
481 | |