| 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 | #ifdef CONFIG_NFS_USE_KERNEL_DNS |
| 10 | |
| 11 | #include <linux/sunrpc/clnt.h> |
| 12 | #include <linux/dns_resolver.h> |
| 13 | |
| 14 | ssize_t nfs_dns_resolve_name(char *name, size_t namelen, |
| 15 | struct sockaddr *sa, size_t salen) |
| 16 | { |
| 17 | ssize_t ret; |
| 18 | char *ip_addr = NULL; |
| 19 | int ip_len; |
| 20 | |
| 21 | ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL); |
| 22 | if (ip_len > 0) |
| 23 | ret = rpc_pton(ip_addr, ip_len, sa, salen); |
| 24 | else |
| 25 | ret = -ESRCH; |
| 26 | kfree(ip_addr); |
| 27 | return ret; |
| 28 | } |
| 29 | |
| 30 | #else |
| 31 | |
| 32 | #include <linux/hash.h> |
| 33 | #include <linux/string.h> |
| 34 | #include <linux/kmod.h> |
| 35 | #include <linux/slab.h> |
| 36 | #include <linux/module.h> |
| 37 | #include <linux/socket.h> |
| 38 | #include <linux/seq_file.h> |
| 39 | #include <linux/inet.h> |
| 40 | #include <linux/sunrpc/clnt.h> |
| 41 | #include <linux/sunrpc/cache.h> |
| 42 | #include <linux/sunrpc/svcauth.h> |
| 43 | |
| 44 | #include "dns_resolve.h" |
| 45 | #include "cache_lib.h" |
| 46 | |
| 47 | #define NFS_DNS_HASHBITS 4 |
| 48 | #define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS) |
| 49 | |
| 50 | static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE]; |
| 51 | |
| 52 | struct nfs_dns_ent { |
| 53 | struct cache_head h; |
| 54 | |
| 55 | char *hostname; |
| 56 | size_t namelen; |
| 57 | |
| 58 | struct sockaddr_storage addr; |
| 59 | size_t addrlen; |
| 60 | }; |
| 61 | |
| 62 | |
| 63 | static void nfs_dns_ent_update(struct cache_head *cnew, |
| 64 | struct cache_head *ckey) |
| 65 | { |
| 66 | struct nfs_dns_ent *new; |
| 67 | struct nfs_dns_ent *key; |
| 68 | |
| 69 | new = container_of(cnew, struct nfs_dns_ent, h); |
| 70 | key = container_of(ckey, struct nfs_dns_ent, h); |
| 71 | |
| 72 | memcpy(&new->addr, &key->addr, key->addrlen); |
| 73 | new->addrlen = key->addrlen; |
| 74 | } |
| 75 | |
| 76 | static void nfs_dns_ent_init(struct cache_head *cnew, |
| 77 | struct cache_head *ckey) |
| 78 | { |
| 79 | struct nfs_dns_ent *new; |
| 80 | struct nfs_dns_ent *key; |
| 81 | |
| 82 | new = container_of(cnew, struct nfs_dns_ent, h); |
| 83 | key = container_of(ckey, struct nfs_dns_ent, h); |
| 84 | |
| 85 | kfree(new->hostname); |
| 86 | new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL); |
| 87 | if (new->hostname) { |
| 88 | new->namelen = key->namelen; |
| 89 | nfs_dns_ent_update(cnew, ckey); |
| 90 | } else { |
| 91 | new->namelen = 0; |
| 92 | new->addrlen = 0; |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | static void nfs_dns_ent_put(struct kref *ref) |
| 97 | { |
| 98 | struct nfs_dns_ent *item; |
| 99 | |
| 100 | item = container_of(ref, struct nfs_dns_ent, h.ref); |
| 101 | kfree(item->hostname); |
| 102 | kfree(item); |
| 103 | } |
| 104 | |
| 105 | static struct cache_head *nfs_dns_ent_alloc(void) |
| 106 | { |
| 107 | struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL); |
| 108 | |
| 109 | if (item != NULL) { |
| 110 | item->hostname = NULL; |
| 111 | item->namelen = 0; |
| 112 | item->addrlen = 0; |
| 113 | return &item->h; |
| 114 | } |
| 115 | return NULL; |
| 116 | }; |
| 117 | |
| 118 | static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key) |
| 119 | { |
| 120 | return hash_str(key->hostname, NFS_DNS_HASHBITS); |
| 121 | } |
| 122 | |
| 123 | static void nfs_dns_request(struct cache_detail *cd, |
| 124 | struct cache_head *ch, |
| 125 | char **bpp, int *blen) |
| 126 | { |
| 127 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); |
| 128 | |
| 129 | qword_add(bpp, blen, key->hostname); |
| 130 | (*bpp)[-1] = '\n'; |
| 131 | } |
| 132 | |
| 133 | static int nfs_dns_upcall(struct cache_detail *cd, |
| 134 | struct cache_head *ch) |
| 135 | { |
| 136 | struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); |
| 137 | int ret; |
| 138 | |
| 139 | ret = nfs_cache_upcall(cd, key->hostname); |
| 140 | if (ret) |
| 141 | ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request); |
| 142 | return ret; |
| 143 | } |
| 144 | |
| 145 | static int nfs_dns_match(struct cache_head *ca, |
| 146 | struct cache_head *cb) |
| 147 | { |
| 148 | struct nfs_dns_ent *a; |
| 149 | struct nfs_dns_ent *b; |
| 150 | |
| 151 | a = container_of(ca, struct nfs_dns_ent, h); |
| 152 | b = container_of(cb, struct nfs_dns_ent, h); |
| 153 | |
| 154 | if (a->namelen == 0 || a->namelen != b->namelen) |
| 155 | return 0; |
| 156 | return memcmp(a->hostname, b->hostname, a->namelen) == 0; |
| 157 | } |
| 158 | |
| 159 | static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd, |
| 160 | struct cache_head *h) |
| 161 | { |
| 162 | struct nfs_dns_ent *item; |
| 163 | long ttl; |
| 164 | |
| 165 | if (h == NULL) { |
| 166 | seq_puts(m, "# ip address hostname ttl\n"); |
| 167 | return 0; |
| 168 | } |
| 169 | item = container_of(h, struct nfs_dns_ent, h); |
| 170 | ttl = item->h.expiry_time - seconds_since_boot(); |
| 171 | if (ttl < 0) |
| 172 | ttl = 0; |
| 173 | |
| 174 | if (!test_bit(CACHE_NEGATIVE, &h->flags)) { |
| 175 | char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1]; |
| 176 | |
| 177 | rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf)); |
| 178 | seq_printf(m, "%15s ", buf); |
| 179 | } else |
| 180 | seq_puts(m, "<none> "); |
| 181 | seq_printf(m, "%15s %ld\n", item->hostname, ttl); |
| 182 | return 0; |
| 183 | } |
| 184 | |
| 185 | static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd, |
| 186 | struct nfs_dns_ent *key) |
| 187 | { |
| 188 | struct cache_head *ch; |
| 189 | |
| 190 | ch = sunrpc_cache_lookup(cd, |
| 191 | &key->h, |
| 192 | nfs_dns_hash(key)); |
| 193 | if (!ch) |
| 194 | return NULL; |
| 195 | return container_of(ch, struct nfs_dns_ent, h); |
| 196 | } |
| 197 | |
| 198 | static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd, |
| 199 | struct nfs_dns_ent *new, |
| 200 | struct nfs_dns_ent *key) |
| 201 | { |
| 202 | struct cache_head *ch; |
| 203 | |
| 204 | ch = sunrpc_cache_update(cd, |
| 205 | &new->h, &key->h, |
| 206 | nfs_dns_hash(key)); |
| 207 | if (!ch) |
| 208 | return NULL; |
| 209 | return container_of(ch, struct nfs_dns_ent, h); |
| 210 | } |
| 211 | |
| 212 | static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen) |
| 213 | { |
| 214 | char buf1[NFS_DNS_HOSTNAME_MAXLEN+1]; |
| 215 | struct nfs_dns_ent key, *item; |
| 216 | unsigned long ttl; |
| 217 | ssize_t len; |
| 218 | int ret = -EINVAL; |
| 219 | |
| 220 | if (buf[buflen-1] != '\n') |
| 221 | goto out; |
| 222 | buf[buflen-1] = '\0'; |
| 223 | |
| 224 | len = qword_get(&buf, buf1, sizeof(buf1)); |
| 225 | if (len <= 0) |
| 226 | goto out; |
| 227 | key.addrlen = rpc_pton(buf1, len, |
| 228 | (struct sockaddr *)&key.addr, |
| 229 | sizeof(key.addr)); |
| 230 | |
| 231 | len = qword_get(&buf, buf1, sizeof(buf1)); |
| 232 | if (len <= 0) |
| 233 | goto out; |
| 234 | |
| 235 | key.hostname = buf1; |
| 236 | key.namelen = len; |
| 237 | memset(&key.h, 0, sizeof(key.h)); |
| 238 | |
| 239 | ttl = get_expiry(&buf); |
| 240 | if (ttl == 0) |
| 241 | goto out; |
| 242 | key.h.expiry_time = ttl + seconds_since_boot(); |
| 243 | |
| 244 | ret = -ENOMEM; |
| 245 | item = nfs_dns_lookup(cd, &key); |
| 246 | if (item == NULL) |
| 247 | goto out; |
| 248 | |
| 249 | if (key.addrlen == 0) |
| 250 | set_bit(CACHE_NEGATIVE, &key.h.flags); |
| 251 | |
| 252 | item = nfs_dns_update(cd, &key, item); |
| 253 | if (item == NULL) |
| 254 | goto out; |
| 255 | |
| 256 | ret = 0; |
| 257 | cache_put(&item->h, cd); |
| 258 | out: |
| 259 | return ret; |
| 260 | } |
| 261 | |
| 262 | static struct cache_detail nfs_dns_resolve = { |
| 263 | .owner = THIS_MODULE, |
| 264 | .hash_size = NFS_DNS_HASHTBL_SIZE, |
| 265 | .hash_table = nfs_dns_table, |
| 266 | .name = "dns_resolve", |
| 267 | .cache_put = nfs_dns_ent_put, |
| 268 | .cache_upcall = nfs_dns_upcall, |
| 269 | .cache_parse = nfs_dns_parse, |
| 270 | .cache_show = nfs_dns_show, |
| 271 | .match = nfs_dns_match, |
| 272 | .init = nfs_dns_ent_init, |
| 273 | .update = nfs_dns_ent_update, |
| 274 | .alloc = nfs_dns_ent_alloc, |
| 275 | }; |
| 276 | |
| 277 | static int do_cache_lookup(struct cache_detail *cd, |
| 278 | struct nfs_dns_ent *key, |
| 279 | struct nfs_dns_ent **item, |
| 280 | struct nfs_cache_defer_req *dreq) |
| 281 | { |
| 282 | int ret = -ENOMEM; |
| 283 | |
| 284 | *item = nfs_dns_lookup(cd, key); |
| 285 | if (*item) { |
| 286 | ret = cache_check(cd, &(*item)->h, &dreq->req); |
| 287 | if (ret) |
| 288 | *item = NULL; |
| 289 | } |
| 290 | return ret; |
| 291 | } |
| 292 | |
| 293 | static int do_cache_lookup_nowait(struct cache_detail *cd, |
| 294 | struct nfs_dns_ent *key, |
| 295 | struct nfs_dns_ent **item) |
| 296 | { |
| 297 | int ret = -ENOMEM; |
| 298 | |
| 299 | *item = nfs_dns_lookup(cd, key); |
| 300 | if (!*item) |
| 301 | goto out_err; |
| 302 | ret = -ETIMEDOUT; |
| 303 | if (!test_bit(CACHE_VALID, &(*item)->h.flags) |
| 304 | || (*item)->h.expiry_time < seconds_since_boot() |
| 305 | || cd->flush_time > (*item)->h.last_refresh) |
| 306 | goto out_put; |
| 307 | ret = -ENOENT; |
| 308 | if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags)) |
| 309 | goto out_put; |
| 310 | return 0; |
| 311 | out_put: |
| 312 | cache_put(&(*item)->h, cd); |
| 313 | out_err: |
| 314 | *item = NULL; |
| 315 | return ret; |
| 316 | } |
| 317 | |
| 318 | static int do_cache_lookup_wait(struct cache_detail *cd, |
| 319 | struct nfs_dns_ent *key, |
| 320 | struct nfs_dns_ent **item) |
| 321 | { |
| 322 | struct nfs_cache_defer_req *dreq; |
| 323 | int ret = -ENOMEM; |
| 324 | |
| 325 | dreq = nfs_cache_defer_req_alloc(); |
| 326 | if (!dreq) |
| 327 | goto out; |
| 328 | ret = do_cache_lookup(cd, key, item, dreq); |
| 329 | if (ret == -EAGAIN) { |
| 330 | ret = nfs_cache_wait_for_upcall(dreq); |
| 331 | if (!ret) |
| 332 | ret = do_cache_lookup_nowait(cd, key, item); |
| 333 | } |
| 334 | nfs_cache_defer_req_put(dreq); |
| 335 | out: |
| 336 | return ret; |
| 337 | } |
| 338 | |
| 339 | ssize_t nfs_dns_resolve_name(char *name, size_t namelen, |
| 340 | struct sockaddr *sa, size_t salen) |
| 341 | { |
| 342 | struct nfs_dns_ent key = { |
| 343 | .hostname = name, |
| 344 | .namelen = namelen, |
| 345 | }; |
| 346 | struct nfs_dns_ent *item = NULL; |
| 347 | ssize_t ret; |
| 348 | |
| 349 | ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item); |
| 350 | if (ret == 0) { |
| 351 | if (salen >= item->addrlen) { |
| 352 | memcpy(sa, &item->addr, item->addrlen); |
| 353 | ret = item->addrlen; |
| 354 | } else |
| 355 | ret = -EOVERFLOW; |
| 356 | cache_put(&item->h, &nfs_dns_resolve); |
| 357 | } else if (ret == -ENOENT) |
| 358 | ret = -ESRCH; |
| 359 | return ret; |
| 360 | } |
| 361 | |
| 362 | int nfs_dns_resolver_init(void) |
| 363 | { |
| 364 | return nfs_cache_register(&nfs_dns_resolve); |
| 365 | } |
| 366 | |
| 367 | void nfs_dns_resolver_destroy(void) |
| 368 | { |
| 369 | nfs_cache_unregister(&nfs_dns_resolve); |
| 370 | } |
| 371 | |
| 372 | #endif |