fs/afs/vl_list.c

   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 }