1 /* AFS vlserver list management. 2 * 3 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/kernel.h> 13 #include <linux/slab.h> 14 #include "internal.h" 15 16 struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len, 17 unsigned short port) 18 { 19 struct afs_vlserver *vlserver; 20 21 vlserver = kzalloc(struct_size(vlserver, name, name_len + 1), 22 GFP_KERNEL); 23 if (vlserver) { 24 atomic_set(&vlserver->usage, 1); 25 rwlock_init(&vlserver->lock); 26 init_waitqueue_head(&vlserver->probe_wq); 27 spin_lock_init(&vlserver->probe_lock); 28 vlserver->name_len = name_len; 29 vlserver->port = port; 30 memcpy(vlserver->name, name, name_len); 31 } 32 return vlserver; 33 } 34 35 static void afs_vlserver_rcu(struct rcu_head *rcu) 36 { 37 struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu); 38 39 afs_put_addrlist(rcu_access_pointer(vlserver->addresses)); 40 kfree_rcu(vlserver, rcu); 41 } 42 43 void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver) 44 { 45 if (vlserver) { 46 unsigned int u = atomic_dec_return(&vlserver->usage); 47 //_debug("VL PUT %p{%u}", vlserver, u); 48 49 if (u == 0) 50 call_rcu(&vlserver->rcu, afs_vlserver_rcu); 51 } 52 } 53 54 struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers) 55 { 56 struct afs_vlserver_list *vllist; 57 58 vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL); 59 if (vllist) { 60 atomic_set(&vllist->usage, 1); 61 rwlock_init(&vllist->lock); 62 } 63 64 return vllist; 65 } 66 67 void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist) 68 { 69 if (vllist) { 70 unsigned int u = atomic_dec_return(&vllist->usage); 71 72 //_debug("VLLS PUT %p{%u}", vllist, u); 73 if (u == 0) { 74 int i; 75 76 for (i = 0; i < vllist->nr_servers; i++) { 77 afs_put_vlserver(net, vllist->servers[i].server); 78 } 79 kfree_rcu(vllist, rcu); 80 } 81 } 82 } 83 84 static u16 afs_extract_le16(const u8 **_b) 85 { 86 u16 val; 87 88 val = (u16)*(*_b)++ << 0; 89 val |= (u16)*(*_b)++ << 8; 90 return val; 91 } 92 93 /* 94 * Build a VL server address list from a DNS queried server list. 95 */ 96 static struct afs_addr_list *afs_extract_vl_addrs(const u8 **_b, const u8 *end, 97 u8 nr_addrs, u16 port) 98 { 99 struct afs_addr_list *alist; 100 const u8 *b = *_b; 101 int ret = -EINVAL; 102 103 alist = afs_alloc_addrlist(nr_addrs, VL_SERVICE, port); 104 if (!alist) 105 return ERR_PTR(-ENOMEM); 106 if (nr_addrs == 0) 107 return alist; 108 109 for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) { 110 struct dns_server_list_v1_address hdr; 111 __be32 x[4]; 112 113 hdr.address_type = *b++; 114 115 switch (hdr.address_type) { 116 case DNS_ADDRESS_IS_IPV4: 117 if (end - b < 4) { 118 _leave(" = -EINVAL [short inet]"); 119 goto error; 120 } 121 memcpy(x, b, 4); 122 afs_merge_fs_addr4(alist, x[0], port); 123 b += 4; 124 break; 125 126 case DNS_ADDRESS_IS_IPV6: 127 if (end - b < 16) { 128 _leave(" = -EINVAL [short inet6]"); 129 goto error; 130 } 131 memcpy(x, b, 16); 132 afs_merge_fs_addr6(alist, x, port); 133 b += 16; 134 break; 135 136 default: 137 _leave(" = -EADDRNOTAVAIL [unknown af %u]", 138 hdr.address_type); 139 ret = -EADDRNOTAVAIL; 140 goto error; 141 } 142 } 143 144 /* Start with IPv6 if available. */ 145 if (alist->nr_ipv4 < alist->nr_addrs) 146 alist->preferred = alist->nr_ipv4; 147 148 *_b = b; 149 return alist; 150 151 error: 152 *_b = b; 153 afs_put_addrlist(alist); 154 return ERR_PTR(ret); 155 } 156 157 /* 158 * Build a VL server list from a DNS queried server list. 159 */ 160 struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell, 161 const void *buffer, 162 size_t buffer_size) 163 { 164 const struct dns_server_list_v1_header *hdr = buffer; 165 struct dns_server_list_v1_server bs; 166 struct afs_vlserver_list *vllist, *previous; 167 struct afs_addr_list *addrs; 168 struct afs_vlserver *server; 169 const u8 *b = buffer, *end = buffer + buffer_size; 170 int ret = -ENOMEM, nr_servers, i, j; 171 172 _enter(""); 173 174 /* Check that it's a server list, v1 */ 175 if (end - b < sizeof(*hdr) || 176 hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST || 177 hdr->hdr.version != 1) { 178 pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n", 179 hdr->hdr.content, hdr->hdr.version, end - b); 180 ret = -EDESTADDRREQ; 181 goto dump; 182 } 183 184 nr_servers = hdr->nr_servers; 185 186 vllist = afs_alloc_vlserver_list(nr_servers); 187 if (!vllist) 188 return ERR_PTR(-ENOMEM); 189 190 vllist->source = (hdr->source < NR__dns_record_source) ? 191 hdr->source : NR__dns_record_source; 192 vllist->status = (hdr->status < NR__dns_lookup_status) ? 193 hdr->status : NR__dns_lookup_status; 194 195 read_lock(&cell->vl_servers_lock); 196 previous = afs_get_vlserverlist( 197 rcu_dereference_protected(cell->vl_servers, 198 lockdep_is_held(&cell->vl_servers_lock))); 199 read_unlock(&cell->vl_servers_lock); 200 201 b += sizeof(*hdr); 202 while (end - b >= sizeof(bs)) { 203 bs.name_len = afs_extract_le16(&b); 204 bs.priority = afs_extract_le16(&b); 205 bs.weight = afs_extract_le16(&b); 206 bs.port = afs_extract_le16(&b); 207 bs.source = *b++; 208 bs.status = *b++; 209 bs.protocol = *b++; 210 bs.nr_addrs = *b++; 211 212 _debug("extract %u %u %u %u %u %u %*.*s", 213 bs.name_len, bs.priority, bs.weight, 214 bs.port, bs.protocol, bs.nr_addrs, 215 bs.name_len, bs.name_len, b); 216 217 if (end - b < bs.name_len) 218 break; 219 220 ret = -EPROTONOSUPPORT; 221 if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) { 222 bs.protocol = DNS_SERVER_PROTOCOL_UDP; 223 } else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) { 224 _leave(" = [proto %u]", bs.protocol); 225 goto error; 226 } 227 228 if (bs.port == 0) 229 bs.port = AFS_VL_PORT; 230 if (bs.source > NR__dns_record_source) 231 bs.source = NR__dns_record_source; 232 if (bs.status > NR__dns_lookup_status) 233 bs.status = NR__dns_lookup_status; 234 235 server = NULL; 236 if (previous) { 237 /* See if we can update an old server record */ 238 for (i = 0; i < previous->nr_servers; i++) { 239 struct afs_vlserver *p = previous->servers[i].server; 240 241 if (p->name_len == bs.name_len && 242 p->port == bs.port && 243 strncasecmp(b, p->name, bs.name_len) == 0) { 244 server = afs_get_vlserver(p); 245 break; 246 } 247 } 248 } 249 250 if (!server) { 251 ret = -ENOMEM; 252 server = afs_alloc_vlserver(b, bs.name_len, bs.port); 253 if (!server) 254 goto error; 255 } 256 257 b += bs.name_len; 258 259 /* Extract the addresses - note that we can't skip this as we 260 * have to advance the payload pointer. 261 */ 262 addrs = afs_extract_vl_addrs(&b, end, bs.nr_addrs, bs.port); 263 if (IS_ERR(addrs)) { 264 ret = PTR_ERR(addrs); 265 goto error_2; 266 } 267 268 if (vllist->nr_servers >= nr_servers) { 269 _debug("skip %u >= %u", vllist->nr_servers, nr_servers); 270 afs_put_addrlist(addrs); 271 afs_put_vlserver(cell->net, server); 272 continue; 273 } 274 275 addrs->source = bs.source; 276 addrs->status = bs.status; 277 278 if (addrs->nr_addrs == 0) { 279 afs_put_addrlist(addrs); 280 if (!rcu_access_pointer(server->addresses)) { 281 afs_put_vlserver(cell->net, server); 282 continue; 283 } 284 } else { 285 struct afs_addr_list *old = addrs; 286 287 write_lock(&server->lock); 288 rcu_swap_protected(server->addresses, old, 289 lockdep_is_held(&server->lock)); 290 write_unlock(&server->lock); 291 afs_put_addrlist(old); 292 } 293 294 295 /* TODO: Might want to check for duplicates */ 296 297 /* Insertion-sort by priority and weight */ 298 for (j = 0; j < vllist->nr_servers; j++) { 299 if (bs.priority < vllist->servers[j].priority) 300 break; /* Lower preferable */ 301 if (bs.priority == vllist->servers[j].priority && 302 bs.weight > vllist->servers[j].weight) 303 break; /* Higher preferable */ 304 } 305 306 if (j < vllist->nr_servers) { 307 memmove(vllist->servers + j + 1, 308 vllist->servers + j, 309 (vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry)); 310 } 311 312 clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags); 313 314 vllist->servers[j].priority = bs.priority; 315 vllist->servers[j].weight = bs.weight; 316 vllist->servers[j].server = server; 317 vllist->nr_servers++; 318 } 319 320 if (b != end) { 321 _debug("parse error %zd", b - end); 322 goto error; 323 } 324 325 afs_put_vlserverlist(cell->net, previous); 326 _leave(" = ok [%u]", vllist->nr_servers); 327 return vllist; 328 329 error_2: 330 afs_put_vlserver(cell->net, server); 331 error: 332 afs_put_vlserverlist(cell->net, vllist); 333 afs_put_vlserverlist(cell->net, previous); 334 dump: 335 if (ret != -ENOMEM) { 336 printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer); 337 print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size); 338 } 339 return ERR_PTR(ret); 340 } 341