Commit | Line | Data |
---|---|---|
e571cbf1 TM |
1 | /* |
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 | ||
9 | #include <linux/hash.h> | |
10 | #include <linux/string.h> | |
11 | #include <linux/kmod.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/socket.h> | |
14 | #include <linux/seq_file.h> | |
15 | #include <linux/inet.h> | |
16 | #include <linux/sunrpc/clnt.h> | |
17 | #include <linux/sunrpc/cache.h> | |
18 | #include <linux/sunrpc/svcauth.h> | |
19 | ||
20 | #include "dns_resolve.h" | |
21 | #include "cache_lib.h" | |
22 | ||
23 | #define NFS_DNS_HASHBITS 4 | |
24 | #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS) | |
25 | ||
26 | static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE]; | |
27 | ||
28 | struct nfs_dns_ent { | |
29 | struct cache_head h; | |
30 | ||
31 | char *hostname; | |
32 | size_t namelen; | |
33 | ||
34 | struct sockaddr_storage addr; | |
35 | size_t addrlen; | |
36 | }; | |
37 | ||
38 | ||
ebed9203 TM |
39 | static void nfs_dns_ent_update(struct cache_head *cnew, |
40 | struct cache_head *ckey) | |
41 | { | |
42 | struct nfs_dns_ent *new; | |
43 | struct nfs_dns_ent *key; | |
44 | ||
45 | new = container_of(cnew, struct nfs_dns_ent, h); | |
46 | key = container_of(ckey, struct nfs_dns_ent, h); | |
47 | ||
48 | memcpy(&new->addr, &key->addr, key->addrlen); | |
49 | new->addrlen = key->addrlen; | |
50 | } | |
51 | ||
e571cbf1 TM |
52 | static void nfs_dns_ent_init(struct cache_head *cnew, |
53 | struct cache_head *ckey) | |
54 | { | |
55 | struct nfs_dns_ent *new; | |
56 | struct nfs_dns_ent *key; | |
57 | ||
58 | new = container_of(cnew, struct nfs_dns_ent, h); | |
59 | key = container_of(ckey, struct nfs_dns_ent, h); | |
60 | ||
61 | kfree(new->hostname); | |
62 | new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL); | |
63 | if (new->hostname) { | |
64 | new->namelen = key->namelen; | |
ebed9203 | 65 | nfs_dns_ent_update(cnew, ckey); |
e571cbf1 TM |
66 | } else { |
67 | new->namelen = 0; | |
68 | new->addrlen = 0; | |
69 | } | |
70 | } | |
71 | ||
72 | static void nfs_dns_ent_put(struct kref *ref) | |
73 | { | |
74 | struct nfs_dns_ent *item; | |
75 | ||
76 | item = container_of(ref, struct nfs_dns_ent, h.ref); | |
77 | kfree(item->hostname); | |
78 | kfree(item); | |
79 | } | |
80 | ||
81 | static struct cache_head *nfs_dns_ent_alloc(void) | |
82 | { | |
83 | struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL); | |
84 | ||
85 | if (item != NULL) { | |
86 | item->hostname = NULL; | |
87 | item->namelen = 0; | |
88 | item->addrlen = 0; | |
89 | return &item->h; | |
90 | } | |
91 | return NULL; | |
92 | }; | |
93 | ||
94 | static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key) | |
95 | { | |
96 | return hash_str(key->hostname, NFS_DNS_HASHBITS); | |
97 | } | |
98 | ||
99 | static void nfs_dns_request(struct cache_detail *cd, | |
100 | struct cache_head *ch, | |
101 | char **bpp, int *blen) | |
102 | { | |
103 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); | |
104 | ||
105 | qword_add(bpp, blen, key->hostname); | |
106 | (*bpp)[-1] = '\n'; | |
107 | } | |
108 | ||
109 | static int nfs_dns_upcall(struct cache_detail *cd, | |
110 | struct cache_head *ch) | |
111 | { | |
112 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); | |
113 | int ret; | |
114 | ||
115 | ret = nfs_cache_upcall(cd, key->hostname); | |
116 | if (ret) | |
117 | ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request); | |
118 | return ret; | |
119 | } | |
120 | ||
121 | static int nfs_dns_match(struct cache_head *ca, | |
122 | struct cache_head *cb) | |
123 | { | |
124 | struct nfs_dns_ent *a; | |
125 | struct nfs_dns_ent *b; | |
126 | ||
127 | a = container_of(ca, struct nfs_dns_ent, h); | |
128 | b = container_of(cb, struct nfs_dns_ent, h); | |
129 | ||
130 | if (a->namelen == 0 || a->namelen != b->namelen) | |
131 | return 0; | |
132 | return memcmp(a->hostname, b->hostname, a->namelen) == 0; | |
133 | } | |
134 | ||
135 | static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd, | |
136 | struct cache_head *h) | |
137 | { | |
138 | struct nfs_dns_ent *item; | |
139 | long ttl; | |
140 | ||
141 | if (h == NULL) { | |
142 | seq_puts(m, "# ip address hostname ttl\n"); | |
143 | return 0; | |
144 | } | |
145 | item = container_of(h, struct nfs_dns_ent, h); | |
146 | ttl = (long)item->h.expiry_time - (long)get_seconds(); | |
147 | if (ttl < 0) | |
148 | ttl = 0; | |
149 | ||
150 | if (!test_bit(CACHE_NEGATIVE, &h->flags)) { | |
151 | char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1]; | |
152 | ||
153 | rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf)); | |
154 | seq_printf(m, "%15s ", buf); | |
155 | } else | |
156 | seq_puts(m, "<none> "); | |
157 | seq_printf(m, "%15s %ld\n", item->hostname, ttl); | |
158 | return 0; | |
159 | } | |
160 | ||
0a6566ec | 161 | static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd, |
e571cbf1 TM |
162 | struct nfs_dns_ent *key) |
163 | { | |
164 | struct cache_head *ch; | |
165 | ||
166 | ch = sunrpc_cache_lookup(cd, | |
167 | &key->h, | |
168 | nfs_dns_hash(key)); | |
169 | if (!ch) | |
170 | return NULL; | |
171 | return container_of(ch, struct nfs_dns_ent, h); | |
172 | } | |
173 | ||
0a6566ec | 174 | static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd, |
e571cbf1 TM |
175 | struct nfs_dns_ent *new, |
176 | struct nfs_dns_ent *key) | |
177 | { | |
178 | struct cache_head *ch; | |
179 | ||
180 | ch = sunrpc_cache_update(cd, | |
181 | &new->h, &key->h, | |
182 | nfs_dns_hash(key)); | |
183 | if (!ch) | |
184 | return NULL; | |
185 | return container_of(ch, struct nfs_dns_ent, h); | |
186 | } | |
187 | ||
188 | static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen) | |
189 | { | |
190 | char buf1[NFS_DNS_HOSTNAME_MAXLEN+1]; | |
191 | struct nfs_dns_ent key, *item; | |
192 | unsigned long ttl; | |
193 | ssize_t len; | |
194 | int ret = -EINVAL; | |
195 | ||
196 | if (buf[buflen-1] != '\n') | |
197 | goto out; | |
198 | buf[buflen-1] = '\0'; | |
199 | ||
200 | len = qword_get(&buf, buf1, sizeof(buf1)); | |
201 | if (len <= 0) | |
202 | goto out; | |
203 | key.addrlen = rpc_pton(buf1, len, | |
204 | (struct sockaddr *)&key.addr, | |
205 | sizeof(key.addr)); | |
206 | ||
207 | len = qword_get(&buf, buf1, sizeof(buf1)); | |
208 | if (len <= 0) | |
209 | goto out; | |
210 | ||
211 | key.hostname = buf1; | |
212 | key.namelen = len; | |
213 | memset(&key.h, 0, sizeof(key.h)); | |
214 | ||
215 | ttl = get_expiry(&buf); | |
216 | if (ttl == 0) | |
217 | goto out; | |
218 | key.h.expiry_time = ttl + get_seconds(); | |
219 | ||
220 | ret = -ENOMEM; | |
221 | item = nfs_dns_lookup(cd, &key); | |
222 | if (item == NULL) | |
223 | goto out; | |
224 | ||
225 | if (key.addrlen == 0) | |
226 | set_bit(CACHE_NEGATIVE, &key.h.flags); | |
227 | ||
228 | item = nfs_dns_update(cd, &key, item); | |
229 | if (item == NULL) | |
230 | goto out; | |
231 | ||
232 | ret = 0; | |
233 | cache_put(&item->h, cd); | |
234 | out: | |
235 | return ret; | |
236 | } | |
237 | ||
238 | static struct cache_detail nfs_dns_resolve = { | |
239 | .owner = THIS_MODULE, | |
240 | .hash_size = NFS_DNS_HASHTBL_SIZE, | |
241 | .hash_table = nfs_dns_table, | |
242 | .name = "dns_resolve", | |
243 | .cache_put = nfs_dns_ent_put, | |
244 | .cache_upcall = nfs_dns_upcall, | |
245 | .cache_parse = nfs_dns_parse, | |
246 | .cache_show = nfs_dns_show, | |
247 | .match = nfs_dns_match, | |
248 | .init = nfs_dns_ent_init, | |
ebed9203 | 249 | .update = nfs_dns_ent_update, |
e571cbf1 TM |
250 | .alloc = nfs_dns_ent_alloc, |
251 | }; | |
252 | ||
253 | static int do_cache_lookup(struct cache_detail *cd, | |
254 | struct nfs_dns_ent *key, | |
255 | struct nfs_dns_ent **item, | |
256 | struct nfs_cache_defer_req *dreq) | |
257 | { | |
258 | int ret = -ENOMEM; | |
259 | ||
260 | *item = nfs_dns_lookup(cd, key); | |
261 | if (*item) { | |
262 | ret = cache_check(cd, &(*item)->h, &dreq->req); | |
263 | if (ret) | |
264 | *item = NULL; | |
265 | } | |
266 | return ret; | |
267 | } | |
268 | ||
269 | static int do_cache_lookup_nowait(struct cache_detail *cd, | |
270 | struct nfs_dns_ent *key, | |
271 | struct nfs_dns_ent **item) | |
272 | { | |
273 | int ret = -ENOMEM; | |
274 | ||
275 | *item = nfs_dns_lookup(cd, key); | |
276 | if (!*item) | |
277 | goto out_err; | |
278 | ret = -ETIMEDOUT; | |
279 | if (!test_bit(CACHE_VALID, &(*item)->h.flags) | |
280 | || (*item)->h.expiry_time < get_seconds() | |
281 | || cd->flush_time > (*item)->h.last_refresh) | |
282 | goto out_put; | |
283 | ret = -ENOENT; | |
284 | if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags)) | |
285 | goto out_put; | |
286 | return 0; | |
287 | out_put: | |
288 | cache_put(&(*item)->h, cd); | |
289 | out_err: | |
290 | *item = NULL; | |
291 | return ret; | |
292 | } | |
293 | ||
294 | static int do_cache_lookup_wait(struct cache_detail *cd, | |
295 | struct nfs_dns_ent *key, | |
296 | struct nfs_dns_ent **item) | |
297 | { | |
298 | struct nfs_cache_defer_req *dreq; | |
299 | int ret = -ENOMEM; | |
300 | ||
301 | dreq = nfs_cache_defer_req_alloc(); | |
302 | if (!dreq) | |
303 | goto out; | |
304 | ret = do_cache_lookup(cd, key, item, dreq); | |
305 | if (ret == -EAGAIN) { | |
306 | ret = nfs_cache_wait_for_upcall(dreq); | |
307 | if (!ret) | |
308 | ret = do_cache_lookup_nowait(cd, key, item); | |
309 | } | |
310 | nfs_cache_defer_req_put(dreq); | |
311 | out: | |
312 | return ret; | |
313 | } | |
314 | ||
315 | ssize_t nfs_dns_resolve_name(char *name, size_t namelen, | |
316 | struct sockaddr *sa, size_t salen) | |
317 | { | |
318 | struct nfs_dns_ent key = { | |
319 | .hostname = name, | |
320 | .namelen = namelen, | |
321 | }; | |
322 | struct nfs_dns_ent *item = NULL; | |
323 | ssize_t ret; | |
324 | ||
325 | ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item); | |
326 | if (ret == 0) { | |
327 | if (salen >= item->addrlen) { | |
328 | memcpy(sa, &item->addr, item->addrlen); | |
329 | ret = item->addrlen; | |
330 | } else | |
331 | ret = -EOVERFLOW; | |
332 | cache_put(&item->h, &nfs_dns_resolve); | |
333 | } else if (ret == -ENOENT) | |
334 | ret = -ESRCH; | |
335 | return ret; | |
336 | } | |
337 | ||
338 | int nfs_dns_resolver_init(void) | |
339 | { | |
340 | return nfs_cache_register(&nfs_dns_resolve); | |
341 | } | |
342 | ||
343 | void nfs_dns_resolver_destroy(void) | |
344 | { | |
345 | nfs_cache_unregister(&nfs_dns_resolve); | |
346 | } | |
347 |