vl_list.c 8.1 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /* AFS vlserver list management.
  3. *
  4. * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
  5. * Written by David Howells (dhowells@redhat.com)
  6. */
  7. #include <linux/kernel.h>
  8. #include <linux/slab.h>
  9. #include "internal.h"
  10. struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
  11. unsigned short port)
  12. {
  13. struct afs_vlserver *vlserver;
  14. vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
  15. GFP_KERNEL);
  16. if (vlserver) {
  17. atomic_set(&vlserver->usage, 1);
  18. rwlock_init(&vlserver->lock);
  19. init_waitqueue_head(&vlserver->probe_wq);
  20. spin_lock_init(&vlserver->probe_lock);
  21. vlserver->rtt = UINT_MAX;
  22. vlserver->name_len = name_len;
  23. vlserver->port = port;
  24. memcpy(vlserver->name, name, name_len);
  25. }
  26. return vlserver;
  27. }
  28. static void afs_vlserver_rcu(struct rcu_head *rcu)
  29. {
  30. struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu);
  31. afs_put_addrlist(rcu_access_pointer(vlserver->addresses));
  32. kfree_rcu(vlserver, rcu);
  33. }
  34. void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)
  35. {
  36. if (vlserver) {
  37. unsigned int u = atomic_dec_return(&vlserver->usage);
  38. //_debug("VL PUT %p{%u}", vlserver, u);
  39. if (u == 0)
  40. call_rcu(&vlserver->rcu, afs_vlserver_rcu);
  41. }
  42. }
  43. struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
  44. {
  45. struct afs_vlserver_list *vllist;
  46. vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);
  47. if (vllist) {
  48. atomic_set(&vllist->usage, 1);
  49. rwlock_init(&vllist->lock);
  50. }
  51. return vllist;
  52. }
  53. void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)
  54. {
  55. if (vllist) {
  56. unsigned int u = atomic_dec_return(&vllist->usage);
  57. //_debug("VLLS PUT %p{%u}", vllist, u);
  58. if (u == 0) {
  59. int i;
  60. for (i = 0; i < vllist->nr_servers; i++) {
  61. afs_put_vlserver(net, vllist->servers[i].server);
  62. }
  63. kfree_rcu(vllist, rcu);
  64. }
  65. }
  66. }
  67. static u16 afs_extract_le16(const u8 **_b)
  68. {
  69. u16 val;
  70. val = (u16)*(*_b)++ << 0;
  71. val |= (u16)*(*_b)++ << 8;
  72. return val;
  73. }
  74. /*
  75. * Build a VL server address list from a DNS queried server list.
  76. */
  77. static struct afs_addr_list *afs_extract_vl_addrs(const u8 **_b, const u8 *end,
  78. u8 nr_addrs, u16 port)
  79. {
  80. struct afs_addr_list *alist;
  81. const u8 *b = *_b;
  82. int ret = -EINVAL;
  83. alist = afs_alloc_addrlist(nr_addrs, VL_SERVICE, port);
  84. if (!alist)
  85. return ERR_PTR(-ENOMEM);
  86. if (nr_addrs == 0)
  87. return alist;
  88. for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
  89. struct dns_server_list_v1_address hdr;
  90. __be32 x[4];
  91. hdr.address_type = *b++;
  92. switch (hdr.address_type) {
  93. case DNS_ADDRESS_IS_IPV4:
  94. if (end - b < 4) {
  95. _leave(" = -EINVAL [short inet]");
  96. goto error;
  97. }
  98. memcpy(x, b, 4);
  99. afs_merge_fs_addr4(alist, x[0], port);
  100. b += 4;
  101. break;
  102. case DNS_ADDRESS_IS_IPV6:
  103. if (end - b < 16) {
  104. _leave(" = -EINVAL [short inet6]");
  105. goto error;
  106. }
  107. memcpy(x, b, 16);
  108. afs_merge_fs_addr6(alist, x, port);
  109. b += 16;
  110. break;
  111. default:
  112. _leave(" = -EADDRNOTAVAIL [unknown af %u]",
  113. hdr.address_type);
  114. ret = -EADDRNOTAVAIL;
  115. goto error;
  116. }
  117. }
  118. /* Start with IPv6 if available. */
  119. if (alist->nr_ipv4 < alist->nr_addrs)
  120. alist->preferred = alist->nr_ipv4;
  121. *_b = b;
  122. return alist;
  123. error:
  124. *_b = b;
  125. afs_put_addrlist(alist);
  126. return ERR_PTR(ret);
  127. }
  128. /*
  129. * Build a VL server list from a DNS queried server list.
  130. */
  131. struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,
  132. const void *buffer,
  133. size_t buffer_size)
  134. {
  135. const struct dns_server_list_v1_header *hdr = buffer;
  136. struct dns_server_list_v1_server bs;
  137. struct afs_vlserver_list *vllist, *previous;
  138. struct afs_addr_list *addrs;
  139. struct afs_vlserver *server;
  140. const u8 *b = buffer, *end = buffer + buffer_size;
  141. int ret = -ENOMEM, nr_servers, i, j;
  142. _enter("");
  143. /* Check that it's a server list, v1 */
  144. if (end - b < sizeof(*hdr) ||
  145. hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||
  146. hdr->hdr.version != 1) {
  147. pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
  148. hdr->hdr.content, hdr->hdr.version, end - b);
  149. ret = -EDESTADDRREQ;
  150. goto dump;
  151. }
  152. nr_servers = hdr->nr_servers;
  153. vllist = afs_alloc_vlserver_list(nr_servers);
  154. if (!vllist)
  155. return ERR_PTR(-ENOMEM);
  156. vllist->source = (hdr->source < NR__dns_record_source) ?
  157. hdr->source : NR__dns_record_source;
  158. vllist->status = (hdr->status < NR__dns_lookup_status) ?
  159. hdr->status : NR__dns_lookup_status;
  160. read_lock(&cell->vl_servers_lock);
  161. previous = afs_get_vlserverlist(
  162. rcu_dereference_protected(cell->vl_servers,
  163. lockdep_is_held(&cell->vl_servers_lock)));
  164. read_unlock(&cell->vl_servers_lock);
  165. b += sizeof(*hdr);
  166. while (end - b >= sizeof(bs)) {
  167. bs.name_len = afs_extract_le16(&b);
  168. bs.priority = afs_extract_le16(&b);
  169. bs.weight = afs_extract_le16(&b);
  170. bs.port = afs_extract_le16(&b);
  171. bs.source = *b++;
  172. bs.status = *b++;
  173. bs.protocol = *b++;
  174. bs.nr_addrs = *b++;
  175. _debug("extract %u %u %u %u %u %u %*.*s",
  176. bs.name_len, bs.priority, bs.weight,
  177. bs.port, bs.protocol, bs.nr_addrs,
  178. bs.name_len, bs.name_len, b);
  179. if (end - b < bs.name_len)
  180. break;
  181. ret = -EPROTONOSUPPORT;
  182. if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
  183. bs.protocol = DNS_SERVER_PROTOCOL_UDP;
  184. } else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
  185. _leave(" = [proto %u]", bs.protocol);
  186. goto error;
  187. }
  188. if (bs.port == 0)
  189. bs.port = AFS_VL_PORT;
  190. if (bs.source > NR__dns_record_source)
  191. bs.source = NR__dns_record_source;
  192. if (bs.status > NR__dns_lookup_status)
  193. bs.status = NR__dns_lookup_status;
  194. /* See if we can update an old server record */
  195. server = NULL;
  196. for (i = 0; i < previous->nr_servers; i++) {
  197. struct afs_vlserver *p = previous->servers[i].server;
  198. if (p->name_len == bs.name_len &&
  199. p->port == bs.port &&
  200. strncasecmp(b, p->name, bs.name_len) == 0) {
  201. server = afs_get_vlserver(p);
  202. break;
  203. }
  204. }
  205. if (!server) {
  206. ret = -ENOMEM;
  207. server = afs_alloc_vlserver(b, bs.name_len, bs.port);
  208. if (!server)
  209. goto error;
  210. }
  211. b += bs.name_len;
  212. /* Extract the addresses - note that we can't skip this as we
  213. * have to advance the payload pointer.
  214. */
  215. addrs = afs_extract_vl_addrs(&b, end, bs.nr_addrs, bs.port);
  216. if (IS_ERR(addrs)) {
  217. ret = PTR_ERR(addrs);
  218. goto error_2;
  219. }
  220. if (vllist->nr_servers >= nr_servers) {
  221. _debug("skip %u >= %u", vllist->nr_servers, nr_servers);
  222. afs_put_addrlist(addrs);
  223. afs_put_vlserver(cell->net, server);
  224. continue;
  225. }
  226. addrs->source = bs.source;
  227. addrs->status = bs.status;
  228. if (addrs->nr_addrs == 0) {
  229. afs_put_addrlist(addrs);
  230. if (!rcu_access_pointer(server->addresses)) {
  231. afs_put_vlserver(cell->net, server);
  232. continue;
  233. }
  234. } else {
  235. struct afs_addr_list *old = addrs;
  236. write_lock(&server->lock);
  237. old = rcu_replace_pointer(server->addresses, old,
  238. lockdep_is_held(&server->lock));
  239. write_unlock(&server->lock);
  240. afs_put_addrlist(old);
  241. }
  242. /* TODO: Might want to check for duplicates */
  243. /* Insertion-sort by priority and weight */
  244. for (j = 0; j < vllist->nr_servers; j++) {
  245. if (bs.priority < vllist->servers[j].priority)
  246. break; /* Lower preferable */
  247. if (bs.priority == vllist->servers[j].priority &&
  248. bs.weight > vllist->servers[j].weight)
  249. break; /* Higher preferable */
  250. }
  251. if (j < vllist->nr_servers) {
  252. memmove(vllist->servers + j + 1,
  253. vllist->servers + j,
  254. (vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));
  255. }
  256. clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
  257. vllist->servers[j].priority = bs.priority;
  258. vllist->servers[j].weight = bs.weight;
  259. vllist->servers[j].server = server;
  260. vllist->nr_servers++;
  261. }
  262. if (b != end) {
  263. _debug("parse error %zd", b - end);
  264. goto error;
  265. }
  266. afs_put_vlserverlist(cell->net, previous);
  267. _leave(" = ok [%u]", vllist->nr_servers);
  268. return vllist;
  269. error_2:
  270. afs_put_vlserver(cell->net, server);
  271. error:
  272. afs_put_vlserverlist(cell->net, vllist);
  273. afs_put_vlserverlist(cell->net, previous);
  274. dump:
  275. if (ret != -ENOMEM) {
  276. printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);
  277. print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);
  278. }
  279. return ERR_PTR(ret);
  280. }