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1// SPDX-License-Identifier: GPL-2.0-or-later2/* 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 12struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,13 unsigned short port)14{15 struct afs_vlserver *vlserver;16 static atomic_t debug_ids;17 18 vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),19 GFP_KERNEL);20 if (vlserver) {21 refcount_set(&vlserver->ref, 1);22 rwlock_init(&vlserver->lock);23 init_waitqueue_head(&vlserver->probe_wq);24 spin_lock_init(&vlserver->probe_lock);25 vlserver->debug_id = atomic_inc_return(&debug_ids);26 vlserver->rtt = UINT_MAX;27 vlserver->name_len = name_len;28 vlserver->service_id = VL_SERVICE;29 vlserver->port = port;30 memcpy(vlserver->name, name, name_len);31 }32 return vlserver;33}34 35static 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 afs_alist_trace_put_vlserver);41 kfree_rcu(vlserver, rcu);42}43 44void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)45{46 if (vlserver &&47 refcount_dec_and_test(&vlserver->ref))48 call_rcu(&vlserver->rcu, afs_vlserver_rcu);49}50 51struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)52{53 struct afs_vlserver_list *vllist;54 55 vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);56 if (vllist) {57 refcount_set(&vllist->ref, 1);58 rwlock_init(&vllist->lock);59 }60 61 return vllist;62}63 64void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)65{66 if (vllist) {67 if (refcount_dec_and_test(&vllist->ref)) {68 int i;69 70 for (i = 0; i < vllist->nr_servers; i++) {71 afs_put_vlserver(net, vllist->servers[i].server);72 }73 kfree_rcu(vllist, rcu);74 }75 }76}77 78static u16 afs_extract_le16(const u8 **_b)79{80 u16 val;81 82 val = (u16)*(*_b)++ << 0;83 val |= (u16)*(*_b)++ << 8;84 return val;85}86 87/*88 * Build a VL server address list from a DNS queried server list.89 */90static struct afs_addr_list *afs_extract_vl_addrs(struct afs_net *net,91 const u8 **_b, const u8 *end,92 u8 nr_addrs, u16 port)93{94 struct afs_addr_list *alist;95 const u8 *b = *_b;96 int ret = -EINVAL;97 98 alist = afs_alloc_addrlist(nr_addrs);99 if (!alist)100 return ERR_PTR(-ENOMEM);101 if (nr_addrs == 0)102 return alist;103 104 for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {105 struct dns_server_list_v1_address hdr;106 __be32 x[4];107 108 hdr.address_type = *b++;109 110 switch (hdr.address_type) {111 case DNS_ADDRESS_IS_IPV4:112 if (end - b < 4) {113 _leave(" = -EINVAL [short inet]");114 goto error;115 }116 memcpy(x, b, 4);117 ret = afs_merge_fs_addr4(net, alist, x[0], port);118 if (ret < 0)119 goto error;120 b += 4;121 break;122 123 case DNS_ADDRESS_IS_IPV6:124 if (end - b < 16) {125 _leave(" = -EINVAL [short inet6]");126 goto error;127 }128 memcpy(x, b, 16);129 ret = afs_merge_fs_addr6(net, alist, x, port);130 if (ret < 0)131 goto error;132 b += 16;133 break;134 135 default:136 _leave(" = -EADDRNOTAVAIL [unknown af %u]",137 hdr.address_type);138 ret = -EADDRNOTAVAIL;139 goto error;140 }141 }142 143 /* Start with IPv6 if available. */144 if (alist->nr_ipv4 < alist->nr_addrs)145 alist->preferred = alist->nr_ipv4;146 147 *_b = b;148 return alist;149 150error:151 *_b = b;152 afs_put_addrlist(alist, afs_alist_trace_put_parse_error);153 return ERR_PTR(ret);154}155 156/*157 * Build a VL server list from a DNS queried server list.158 */159struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,160 const void *buffer,161 size_t buffer_size)162{163 const struct dns_server_list_v1_header *hdr = buffer;164 struct dns_server_list_v1_server bs;165 struct afs_vlserver_list *vllist, *previous;166 struct afs_addr_list *addrs;167 struct afs_vlserver *server;168 const u8 *b = buffer, *end = buffer + buffer_size;169 int ret = -ENOMEM, nr_servers, i, j;170 171 _enter("");172 173 /* Check that it's a server list, v1 */174 if (end - b < sizeof(*hdr) ||175 hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||176 hdr->hdr.version != 1) {177 pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",178 hdr->hdr.content, hdr->hdr.version, end - b);179 ret = -EDESTADDRREQ;180 goto dump;181 }182 183 nr_servers = hdr->nr_servers;184 185 vllist = afs_alloc_vlserver_list(nr_servers);186 if (!vllist)187 return ERR_PTR(-ENOMEM);188 189 vllist->source = (hdr->source < NR__dns_record_source) ?190 hdr->source : NR__dns_record_source;191 vllist->status = (hdr->status < NR__dns_lookup_status) ?192 hdr->status : NR__dns_lookup_status;193 194 read_lock(&cell->vl_servers_lock);195 previous = afs_get_vlserverlist(196 rcu_dereference_protected(cell->vl_servers,197 lockdep_is_held(&cell->vl_servers_lock)));198 read_unlock(&cell->vl_servers_lock);199 200 b += sizeof(*hdr);201 while (end - b >= sizeof(bs)) {202 bs.name_len = afs_extract_le16(&b);203 bs.priority = afs_extract_le16(&b);204 bs.weight = afs_extract_le16(&b);205 bs.port = afs_extract_le16(&b);206 bs.source = *b++;207 bs.status = *b++;208 bs.protocol = *b++;209 bs.nr_addrs = *b++;210 211 _debug("extract %u %u %u %u %u %u %*.*s",212 bs.name_len, bs.priority, bs.weight,213 bs.port, bs.protocol, bs.nr_addrs,214 bs.name_len, bs.name_len, b);215 216 if (end - b < bs.name_len)217 break;218 219 ret = -EPROTONOSUPPORT;220 if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {221 bs.protocol = DNS_SERVER_PROTOCOL_UDP;222 } else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {223 _leave(" = [proto %u]", bs.protocol);224 goto error;225 }226 227 if (bs.port == 0)228 bs.port = AFS_VL_PORT;229 if (bs.source > NR__dns_record_source)230 bs.source = NR__dns_record_source;231 if (bs.status > NR__dns_lookup_status)232 bs.status = NR__dns_lookup_status;233 234 /* See if we can update an old server record */235 server = NULL;236 for (i = 0; i < previous->nr_servers; i++) {237 struct afs_vlserver *p = previous->servers[i].server;238 239 if (p->name_len == bs.name_len &&240 p->port == bs.port &&241 strncasecmp(b, p->name, bs.name_len) == 0) {242 server = afs_get_vlserver(p);243 break;244 }245 }246 247 if (!server) {248 ret = -ENOMEM;249 server = afs_alloc_vlserver(b, bs.name_len, bs.port);250 if (!server)251 goto error;252 }253 254 b += bs.name_len;255 256 /* Extract the addresses - note that we can't skip this as we257 * have to advance the payload pointer.258 */259 addrs = afs_extract_vl_addrs(cell->net, &b, end, bs.nr_addrs, bs.port);260 if (IS_ERR(addrs)) {261 ret = PTR_ERR(addrs);262 goto error_2;263 }264 265 if (vllist->nr_servers >= nr_servers) {266 _debug("skip %u >= %u", vllist->nr_servers, nr_servers);267 afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);268 afs_put_vlserver(cell->net, server);269 continue;270 }271 272 addrs->source = bs.source;273 addrs->status = bs.status;274 275 if (addrs->nr_addrs == 0) {276 afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);277 if (!rcu_access_pointer(server->addresses)) {278 afs_put_vlserver(cell->net, server);279 continue;280 }281 } else {282 struct afs_addr_list *old = addrs;283 284 write_lock(&server->lock);285 old = rcu_replace_pointer(server->addresses, old,286 lockdep_is_held(&server->lock));287 write_unlock(&server->lock);288 afs_put_addrlist(old, afs_alist_trace_put_vlserver_old);289 }290 291 292 /* TODO: Might want to check for duplicates */293 294 /* Insertion-sort by priority and weight */295 for (j = 0; j < vllist->nr_servers; j++) {296 if (bs.priority < vllist->servers[j].priority)297 break; /* Lower preferable */298 if (bs.priority == vllist->servers[j].priority &&299 bs.weight > vllist->servers[j].weight)300 break; /* Higher preferable */301 }302 303 if (j < vllist->nr_servers) {304 memmove(vllist->servers + j + 1,305 vllist->servers + j,306 (vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));307 }308 309 clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);310 311 vllist->servers[j].priority = bs.priority;312 vllist->servers[j].weight = bs.weight;313 vllist->servers[j].server = server;314 vllist->nr_servers++;315 }316 317 if (b != end) {318 _debug("parse error %zd", b - end);319 goto error;320 }321 322 afs_put_vlserverlist(cell->net, previous);323 _leave(" = ok [%u]", vllist->nr_servers);324 return vllist;325 326error_2:327 afs_put_vlserver(cell->net, server);328error:329 afs_put_vlserverlist(cell->net, vllist);330 afs_put_vlserverlist(cell->net, previous);331dump:332 if (ret != -ENOMEM) {333 printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);334 print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);335 }336 return ERR_PTR(ret);337}338