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Trond Myklebuste571cbf2009-08-19 18:12:27 -04001/*
2 * linux/fs/nfs/dns_resolve.c
3 *
4 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
5 *
6 * Resolves DNS hostnames into valid ip addresses
7 */
8
Bryan Schumakerc2e81392010-08-11 09:37:53 +01009#ifdef CONFIG_NFS_USE_KERNEL_DNS
10
Bryan Schumaker89d77c82012-07-30 16:05:25 -040011#include <linux/module.h>
Bryan Schumakerc2e81392010-08-11 09:37:53 +010012#include <linux/sunrpc/clnt.h>
Jeff Layton59766872013-02-04 12:50:00 -050013#include <linux/sunrpc/addr.h>
Bryan Schumakerc2e81392010-08-11 09:37:53 +010014#include <linux/dns_resolver.h>
Trond Myklebust17280172012-03-11 13:11:00 -040015#include "dns_resolve.h"
Bryan Schumakerc2e81392010-08-11 09:37:53 +010016
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +030017ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen,
Bryan Schumakerc2e81392010-08-11 09:37:53 +010018 struct sockaddr *sa, size_t salen)
19{
20 ssize_t ret;
21 char *ip_addr = NULL;
22 int ip_len;
23
24 ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
25 if (ip_len > 0)
Stanislav Kinsburskybc224f52012-01-26 15:11:33 +040026 ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
Bryan Schumakerc2e81392010-08-11 09:37:53 +010027 else
28 ret = -ESRCH;
29 kfree(ip_addr);
30 return ret;
31}
Bryan Schumaker89d77c82012-07-30 16:05:25 -040032EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
Bryan Schumakerc2e81392010-08-11 09:37:53 +010033
34#else
35
Bryan Schumaker89d77c82012-07-30 16:05:25 -040036#include <linux/module.h>
Trond Myklebuste571cbf2009-08-19 18:12:27 -040037#include <linux/hash.h>
38#include <linux/string.h>
39#include <linux/kmod.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090040#include <linux/slab.h>
Trond Myklebuste571cbf2009-08-19 18:12:27 -040041#include <linux/module.h>
42#include <linux/socket.h>
43#include <linux/seq_file.h>
44#include <linux/inet.h>
45#include <linux/sunrpc/clnt.h>
Jeff Layton59766872013-02-04 12:50:00 -050046#include <linux/sunrpc/addr.h>
Trond Myklebuste571cbf2009-08-19 18:12:27 -040047#include <linux/sunrpc/cache.h>
48#include <linux/sunrpc/svcauth.h>
Stanislav Kinsbursky9df69c82011-11-25 17:13:12 +030049#include <linux/sunrpc/rpc_pipe_fs.h>
Trond Myklebuste571cbf2009-08-19 18:12:27 -040050
51#include "dns_resolve.h"
52#include "cache_lib.h"
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +030053#include "netns.h"
Trond Myklebuste571cbf2009-08-19 18:12:27 -040054
55#define NFS_DNS_HASHBITS 4
56#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
57
Trond Myklebuste571cbf2009-08-19 18:12:27 -040058struct nfs_dns_ent {
59 struct cache_head h;
60
61 char *hostname;
62 size_t namelen;
63
64 struct sockaddr_storage addr;
65 size_t addrlen;
66};
67
68
Trond Myklebustebed9202010-03-02 13:06:22 -050069static void nfs_dns_ent_update(struct cache_head *cnew,
70 struct cache_head *ckey)
71{
72 struct nfs_dns_ent *new;
73 struct nfs_dns_ent *key;
74
75 new = container_of(cnew, struct nfs_dns_ent, h);
76 key = container_of(ckey, struct nfs_dns_ent, h);
77
78 memcpy(&new->addr, &key->addr, key->addrlen);
79 new->addrlen = key->addrlen;
80}
81
Trond Myklebuste571cbf2009-08-19 18:12:27 -040082static void nfs_dns_ent_init(struct cache_head *cnew,
83 struct cache_head *ckey)
84{
85 struct nfs_dns_ent *new;
86 struct nfs_dns_ent *key;
87
88 new = container_of(cnew, struct nfs_dns_ent, h);
89 key = container_of(ckey, struct nfs_dns_ent, h);
90
91 kfree(new->hostname);
92 new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
93 if (new->hostname) {
94 new->namelen = key->namelen;
Trond Myklebustebed9202010-03-02 13:06:22 -050095 nfs_dns_ent_update(cnew, ckey);
Trond Myklebuste571cbf2009-08-19 18:12:27 -040096 } else {
97 new->namelen = 0;
98 new->addrlen = 0;
99 }
100}
101
102static void nfs_dns_ent_put(struct kref *ref)
103{
104 struct nfs_dns_ent *item;
105
106 item = container_of(ref, struct nfs_dns_ent, h.ref);
107 kfree(item->hostname);
108 kfree(item);
109}
110
111static struct cache_head *nfs_dns_ent_alloc(void)
112{
113 struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
114
115 if (item != NULL) {
116 item->hostname = NULL;
117 item->namelen = 0;
118 item->addrlen = 0;
119 return &item->h;
120 }
121 return NULL;
122};
123
124static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
125{
126 return hash_str(key->hostname, NFS_DNS_HASHBITS);
127}
128
129static void nfs_dns_request(struct cache_detail *cd,
130 struct cache_head *ch,
131 char **bpp, int *blen)
132{
133 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
134
135 qword_add(bpp, blen, key->hostname);
136 (*bpp)[-1] = '\n';
137}
138
139static int nfs_dns_upcall(struct cache_detail *cd,
140 struct cache_head *ch)
141{
142 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
143 int ret;
144
145 ret = nfs_cache_upcall(cd, key->hostname);
146 if (ret)
147 ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
148 return ret;
149}
150
151static int nfs_dns_match(struct cache_head *ca,
152 struct cache_head *cb)
153{
154 struct nfs_dns_ent *a;
155 struct nfs_dns_ent *b;
156
157 a = container_of(ca, struct nfs_dns_ent, h);
158 b = container_of(cb, struct nfs_dns_ent, h);
159
160 if (a->namelen == 0 || a->namelen != b->namelen)
161 return 0;
162 return memcmp(a->hostname, b->hostname, a->namelen) == 0;
163}
164
165static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
166 struct cache_head *h)
167{
168 struct nfs_dns_ent *item;
169 long ttl;
170
171 if (h == NULL) {
172 seq_puts(m, "# ip address hostname ttl\n");
173 return 0;
174 }
175 item = container_of(h, struct nfs_dns_ent, h);
NeilBrownc5b29f82010-08-12 16:55:22 +1000176 ttl = item->h.expiry_time - seconds_since_boot();
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400177 if (ttl < 0)
178 ttl = 0;
179
180 if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
181 char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
182
183 rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
184 seq_printf(m, "%15s ", buf);
185 } else
186 seq_puts(m, "<none> ");
187 seq_printf(m, "%15s %ld\n", item->hostname, ttl);
188 return 0;
189}
190
Trond Myklebust0a6566e2009-12-03 15:54:01 -0500191static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400192 struct nfs_dns_ent *key)
193{
194 struct cache_head *ch;
195
196 ch = sunrpc_cache_lookup(cd,
197 &key->h,
198 nfs_dns_hash(key));
199 if (!ch)
200 return NULL;
201 return container_of(ch, struct nfs_dns_ent, h);
202}
203
Trond Myklebust0a6566e2009-12-03 15:54:01 -0500204static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400205 struct nfs_dns_ent *new,
206 struct nfs_dns_ent *key)
207{
208 struct cache_head *ch;
209
210 ch = sunrpc_cache_update(cd,
211 &new->h, &key->h,
212 nfs_dns_hash(key));
213 if (!ch)
214 return NULL;
215 return container_of(ch, struct nfs_dns_ent, h);
216}
217
218static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
219{
220 char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
221 struct nfs_dns_ent key, *item;
NeilBrown8d96b102012-10-31 12:16:01 +1100222 unsigned int ttl;
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400223 ssize_t len;
224 int ret = -EINVAL;
225
226 if (buf[buflen-1] != '\n')
227 goto out;
228 buf[buflen-1] = '\0';
229
230 len = qword_get(&buf, buf1, sizeof(buf1));
231 if (len <= 0)
232 goto out;
Stanislav Kinsbursky599ec122012-01-19 18:51:04 +0400233 key.addrlen = rpc_pton(cd->net, buf1, len,
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400234 (struct sockaddr *)&key.addr,
235 sizeof(key.addr));
236
237 len = qword_get(&buf, buf1, sizeof(buf1));
238 if (len <= 0)
239 goto out;
240
241 key.hostname = buf1;
242 key.namelen = len;
243 memset(&key.h, 0, sizeof(key.h));
244
NeilBrown8d96b102012-10-31 12:16:01 +1100245 if (get_uint(&buf, &ttl) < 0)
246 goto out;
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400247 if (ttl == 0)
248 goto out;
NeilBrownc5b29f82010-08-12 16:55:22 +1000249 key.h.expiry_time = ttl + seconds_since_boot();
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400250
251 ret = -ENOMEM;
252 item = nfs_dns_lookup(cd, &key);
253 if (item == NULL)
254 goto out;
255
256 if (key.addrlen == 0)
257 set_bit(CACHE_NEGATIVE, &key.h.flags);
258
259 item = nfs_dns_update(cd, &key, item);
260 if (item == NULL)
261 goto out;
262
263 ret = 0;
264 cache_put(&item->h, cd);
265out:
266 return ret;
267}
268
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400269static int do_cache_lookup(struct cache_detail *cd,
270 struct nfs_dns_ent *key,
271 struct nfs_dns_ent **item,
272 struct nfs_cache_defer_req *dreq)
273{
274 int ret = -ENOMEM;
275
276 *item = nfs_dns_lookup(cd, key);
277 if (*item) {
278 ret = cache_check(cd, &(*item)->h, &dreq->req);
279 if (ret)
280 *item = NULL;
281 }
282 return ret;
283}
284
285static int do_cache_lookup_nowait(struct cache_detail *cd,
286 struct nfs_dns_ent *key,
287 struct nfs_dns_ent **item)
288{
289 int ret = -ENOMEM;
290
291 *item = nfs_dns_lookup(cd, key);
292 if (!*item)
293 goto out_err;
294 ret = -ETIMEDOUT;
295 if (!test_bit(CACHE_VALID, &(*item)->h.flags)
NeilBrownc5b29f82010-08-12 16:55:22 +1000296 || (*item)->h.expiry_time < seconds_since_boot()
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400297 || cd->flush_time > (*item)->h.last_refresh)
298 goto out_put;
299 ret = -ENOENT;
300 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
301 goto out_put;
302 return 0;
303out_put:
304 cache_put(&(*item)->h, cd);
305out_err:
306 *item = NULL;
307 return ret;
308}
309
310static int do_cache_lookup_wait(struct cache_detail *cd,
311 struct nfs_dns_ent *key,
312 struct nfs_dns_ent **item)
313{
314 struct nfs_cache_defer_req *dreq;
315 int ret = -ENOMEM;
316
317 dreq = nfs_cache_defer_req_alloc();
318 if (!dreq)
319 goto out;
320 ret = do_cache_lookup(cd, key, item, dreq);
321 if (ret == -EAGAIN) {
322 ret = nfs_cache_wait_for_upcall(dreq);
323 if (!ret)
324 ret = do_cache_lookup_nowait(cd, key, item);
325 }
326 nfs_cache_defer_req_put(dreq);
327out:
328 return ret;
329}
330
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300331ssize_t nfs_dns_resolve_name(struct net *net, char *name,
332 size_t namelen, struct sockaddr *sa, size_t salen)
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400333{
334 struct nfs_dns_ent key = {
335 .hostname = name,
336 .namelen = namelen,
337 };
338 struct nfs_dns_ent *item = NULL;
339 ssize_t ret;
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300340 struct nfs_net *nn = net_generic(net, nfs_net_id);
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400341
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300342 ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400343 if (ret == 0) {
344 if (salen >= item->addrlen) {
345 memcpy(sa, &item->addr, item->addrlen);
346 ret = item->addrlen;
347 } else
348 ret = -EOVERFLOW;
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300349 cache_put(&item->h, nn->nfs_dns_resolve);
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400350 } else if (ret == -ENOENT)
351 ret = -ESRCH;
352 return ret;
353}
Bryan Schumaker89d77c82012-07-30 16:05:25 -0400354EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400355
Stanislav Kinsbursky483479c2013-02-04 14:02:35 +0300356static struct cache_detail nfs_dns_resolve_template = {
357 .owner = THIS_MODULE,
358 .hash_size = NFS_DNS_HASHTBL_SIZE,
359 .name = "dns_resolve",
360 .cache_put = nfs_dns_ent_put,
361 .cache_upcall = nfs_dns_upcall,
362 .cache_parse = nfs_dns_parse,
363 .cache_show = nfs_dns_show,
364 .match = nfs_dns_match,
365 .init = nfs_dns_ent_init,
366 .update = nfs_dns_ent_update,
367 .alloc = nfs_dns_ent_alloc,
368};
369
370
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300371int nfs_dns_resolver_cache_init(struct net *net)
372{
Stanislav Kinsbursky483479c2013-02-04 14:02:35 +0300373 int err;
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300374 struct nfs_net *nn = net_generic(net, nfs_net_id);
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300375
Stanislav Kinsbursky483479c2013-02-04 14:02:35 +0300376 nn->nfs_dns_resolve = cache_create_net(&nfs_dns_resolve_template, net);
377 if (IS_ERR(nn->nfs_dns_resolve))
378 return PTR_ERR(nn->nfs_dns_resolve);
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300379
Stanislav Kinsbursky483479c2013-02-04 14:02:35 +0300380 nfs_cache_init(nn->nfs_dns_resolve);
381 err = nfs_cache_register_net(net, nn->nfs_dns_resolve);
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300382 if (err)
383 goto err_reg;
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300384 return 0;
385
386err_reg:
Stanislav Kinsbursky483479c2013-02-04 14:02:35 +0300387 nfs_cache_destroy(nn->nfs_dns_resolve);
388 cache_destroy_net(nn->nfs_dns_resolve, net);
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300389 return err;
390}
391
392void nfs_dns_resolver_cache_destroy(struct net *net)
393{
394 struct nfs_net *nn = net_generic(net, nfs_net_id);
395 struct cache_detail *cd = nn->nfs_dns_resolve;
396
397 nfs_cache_unregister_net(net, cd);
398 nfs_cache_destroy(cd);
Stanislav Kinsbursky483479c2013-02-04 14:02:35 +0300399 cache_destroy_net(nn->nfs_dns_resolve, net);
Stanislav Kinsbursky1b340d02011-11-25 17:13:04 +0300400}
401
Stanislav Kinsbursky9df69c82011-11-25 17:13:12 +0300402static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
403 void *ptr)
404{
405 struct super_block *sb = ptr;
406 struct net *net = sb->s_fs_info;
407 struct nfs_net *nn = net_generic(net, nfs_net_id);
408 struct cache_detail *cd = nn->nfs_dns_resolve;
409 int ret = 0;
410
411 if (cd == NULL)
412 return 0;
413
414 if (!try_module_get(THIS_MODULE))
415 return 0;
416
417 switch (event) {
418 case RPC_PIPEFS_MOUNT:
419 ret = nfs_cache_register_sb(sb, cd);
420 break;
421 case RPC_PIPEFS_UMOUNT:
422 nfs_cache_unregister_sb(sb, cd);
423 break;
424 default:
425 ret = -ENOTSUPP;
426 break;
427 }
428 module_put(THIS_MODULE);
429 return ret;
430}
431
432static struct notifier_block nfs_dns_resolver_block = {
433 .notifier_call = rpc_pipefs_event,
434};
435
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400436int nfs_dns_resolver_init(void)
437{
Stanislav Kinsbursky9df69c82011-11-25 17:13:12 +0300438 return rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400439}
440
441void nfs_dns_resolver_destroy(void)
442{
Stanislav Kinsbursky9df69c82011-11-25 17:13:12 +0300443 rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
Trond Myklebuste571cbf2009-08-19 18:12:27 -0400444}
Bryan Schumakerc2e81392010-08-11 09:37:53 +0100445#endif