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(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 }