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