fs/afs/vl_list.c

   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(struct afs_net *net,
  87                                                   const u8 **_b, const u8 *end,
  88                                                   u8 nr_addrs, u16 port)
  89 {
  90         struct afs_addr_list *alist;
  91         const u8 *b = *_b;
  92         int ret = -EINVAL;
  93
  94         alist = afs_alloc_addrlist(nr_addrs, VL_SERVICE);
  95         if (!alist)
  96                 return ERR_PTR(-ENOMEM);
  97         if (nr_addrs == 0)
  98                 return alist;
  99
 100         for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
 101                 struct dns_server_list_v1_address hdr;
 102                 __be32 x[4];
 103
 104                 hdr.address_type = *b++;
 105
 106                 switch (hdr.address_type) {
 107                 case DNS_ADDRESS_IS_IPV4:
 108                         if (end - b < 4) {
 109                                 _leave(" = -EINVAL [short inet]");
 110                                 goto error;
 111                         }
 112                         memcpy(x, b, 4);
 113                         ret = afs_merge_fs_addr4(net, alist, x[0], port);
 114                         if (ret < 0)
 115                                 goto error;
 116                         b += 4;
 117                         break;
 118
 119                 case DNS_ADDRESS_IS_IPV6:
 120                         if (end - b < 16) {
 121                                 _leave(" = -EINVAL [short inet6]");
 122                                 goto error;
 123                         }
 124                         memcpy(x, b, 16);
 125                         ret = afs_merge_fs_addr6(net, alist, x, port);
 126                         if (ret < 0)
 127                                 goto error;
 128                         b += 16;
 129                         break;
 130
 131                 default:
 132                         _leave(" = -EADDRNOTAVAIL [unknown af %u]",
 133                                hdr.address_type);
 134                         ret = -EADDRNOTAVAIL;
 135                         goto error;
 136                 }
 137         }
 138
 139         /* Start with IPv6 if available. */
 140         if (alist->nr_ipv4 < alist->nr_addrs)
 141                 alist->preferred = alist->nr_ipv4;
 142
 143         *_b = b;
 144         return alist;
 145
 146 error:
 147         *_b = b;
 148         afs_put_addrlist(alist);
 149         return ERR_PTR(ret);
 150 }
 151
 152 /*
 153  * Build a VL server list from a DNS queried server list.
 154  */
 155 struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,
 156                                                     const void *buffer,
 157                                                     size_t buffer_size)
 158 {
 159         const struct dns_server_list_v1_header *hdr = buffer;
 160         struct dns_server_list_v1_server bs;
 161         struct afs_vlserver_list *vllist, *previous;
 162         struct afs_addr_list *addrs;
 163         struct afs_vlserver *server;
 164         const u8 *b = buffer, *end = buffer + buffer_size;
 165         int ret = -ENOMEM, nr_servers, i, j;
 166
 167         _enter("");
 168
 169         /* Check that it's a server list, v1 */
 170         if (end - b < sizeof(*hdr) ||
 171             hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||
 172             hdr->hdr.version != 1) {
 173                 pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
 174                           hdr->hdr.content, hdr->hdr.version, end - b);
 175                 ret = -EDESTADDRREQ;
 176                 goto dump;
 177         }
 178
 179         nr_servers = hdr->nr_servers;
 180
 181         vllist = afs_alloc_vlserver_list(nr_servers);
 182         if (!vllist)
 183                 return ERR_PTR(-ENOMEM);
 184
 185         vllist->source = (hdr->source < NR__dns_record_source) ?
 186                 hdr->source : NR__dns_record_source;
 187         vllist->status = (hdr->status < NR__dns_lookup_status) ?
 188                 hdr->status : NR__dns_lookup_status;
 189
 190         read_lock(&cell->vl_servers_lock);
 191         previous = afs_get_vlserverlist(
 192                 rcu_dereference_protected(cell->vl_servers,
 193                                           lockdep_is_held(&cell->vl_servers_lock)));
 194         read_unlock(&cell->vl_servers_lock);
 195
 196         b += sizeof(*hdr);
 197         while (end - b >= sizeof(bs)) {
 198                 bs.name_len     = afs_extract_le16(&b);
 199                 bs.priority     = afs_extract_le16(&b);
 200                 bs.weight       = afs_extract_le16(&b);
 201                 bs.port         = afs_extract_le16(&b);
 202                 bs.source       = *b++;
 203                 bs.status       = *b++;
 204                 bs.protocol     = *b++;
 205                 bs.nr_addrs     = *b++;
 206
 207                 _debug("extract %u %u %u %u %u %u %*.*s",
 208                        bs.name_len, bs.priority, bs.weight,
 209                        bs.port, bs.protocol, bs.nr_addrs,
 210                        bs.name_len, bs.name_len, b);
 211
 212                 if (end - b < bs.name_len)
 213                         break;
 214
 215                 ret = -EPROTONOSUPPORT;
 216                 if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
 217                         bs.protocol = DNS_SERVER_PROTOCOL_UDP;
 218                 } else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
 219                         _leave(" = [proto %u]", bs.protocol);
 220                         goto error;
 221                 }
 222
 223                 if (bs.port == 0)
 224                         bs.port = AFS_VL_PORT;
 225                 if (bs.source > NR__dns_record_source)
 226                         bs.source = NR__dns_record_source;
 227                 if (bs.status > NR__dns_lookup_status)
 228                         bs.status = NR__dns_lookup_status;
 229
 230                 /* See if we can update an old server record */
 231                 server = NULL;
 232                 for (i = 0; i < previous->nr_servers; i++) {
 233                         struct afs_vlserver *p = previous->servers[i].server;
 234
 235                         if (p->name_len == bs.name_len &&
 236                             p->port == bs.port &&
 237                             strncasecmp(b, p->name, bs.name_len) == 0) {
 238                                 server = afs_get_vlserver(p);
 239                                 break;
 240                         }
 241                 }
 242
 243                 if (!server) {
 244                         ret = -ENOMEM;
 245                         server = afs_alloc_vlserver(b, bs.name_len, bs.port);
 246                         if (!server)
 247                                 goto error;
 248                 }
 249
 250                 b += bs.name_len;
 251
 252                 /* Extract the addresses - note that we can't skip this as we
 253                  * have to advance the payload pointer.
 254                  */
 255                 addrs = afs_extract_vl_addrs(cell->net, &b, end, bs.nr_addrs, bs.port);
 256                 if (IS_ERR(addrs)) {
 257                         ret = PTR_ERR(addrs);
 258                         goto error_2;
 259                 }
 260
 261                 if (vllist->nr_servers >= nr_servers) {
 262                         _debug("skip %u >= %u", vllist->nr_servers, nr_servers);
 263                         afs_put_addrlist(addrs);
 264                         afs_put_vlserver(cell->net, server);
 265                         continue;
 266                 }
 267
 268                 addrs->source = bs.source;
 269                 addrs->status = bs.status;
 270
 271                 if (addrs->nr_addrs == 0) {
 272                         afs_put_addrlist(addrs);
 273                         if (!rcu_access_pointer(server->addresses)) {
 274                                 afs_put_vlserver(cell->net, server);
 275                                 continue;
 276                         }
 277                 } else {
 278                         struct afs_addr_list *old = addrs;
 279
 280                         write_lock(&server->lock);
 281                         old = rcu_replace_pointer(server->addresses, old,
 282                                                   lockdep_is_held(&server->lock));
 283                         write_unlock(&server->lock);
 284                         afs_put_addrlist(old);
 285                 }
 286
 287
 288                 /* TODO: Might want to check for duplicates */
 289
 290                 /* Insertion-sort by priority and weight */
 291                 for (j = 0; j < vllist->nr_servers; j++) {
 292                         if (bs.priority < vllist->servers[j].priority)
 293                                 break; /* Lower preferable */
 294                         if (bs.priority == vllist->servers[j].priority &&
 295                             bs.weight > vllist->servers[j].weight)
 296                                 break; /* Higher preferable */
 297                 }
 298
 299                 if (j < vllist->nr_servers) {
 300                         memmove(vllist->servers + j + 1,
 301                                 vllist->servers + j,
 302                                 (vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));
 303                 }
 304
 305                 clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
 306
 307                 vllist->servers[j].priority = bs.priority;
 308                 vllist->servers[j].weight = bs.weight;
 309                 vllist->servers[j].server = server;
 310                 vllist->nr_servers++;
 311         }
 312
 313         if (b != end) {
 314                 _debug("parse error %zd", b - end);
 315                 goto error;
 316         }
 317
 318         afs_put_vlserverlist(cell->net, previous);
 319         _leave(" = ok [%u]", vllist->nr_servers);
 320         return vllist;
 321
 322 error_2:
 323         afs_put_vlserver(cell->net, server);
 324 error:
 325         afs_put_vlserverlist(cell->net, vllist);
 326         afs_put_vlserverlist(cell->net, previous);
 327 dump:
 328         if (ret != -ENOMEM) {
 329                 printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);
 330                 print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);
 331         }
 332         return ERR_PTR(ret);
 333 }