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