fs/afs/addr_list.c

   1 /* Server address list management
   2  *
   3  * Copyright (C) 2017 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 Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/ctype.h>
  14 #include <linux/dns_resolver.h>
  15 #include <linux/inet.h>
  16 #include <keys/rxrpc-type.h>
  17 #include "internal.h"
  18 #include "afs_fs.h"
  19
  20 //#define AFS_MAX_ADDRESSES
  21 //      ((unsigned int)((PAGE_SIZE - sizeof(struct afs_addr_list)) /
  22 //                      sizeof(struct sockaddr_rxrpc)))
  23 #define AFS_MAX_ADDRESSES ((unsigned int)(sizeof(unsigned long) * 8))
  24
  25 /*
  26  * Release an address list.
  27  */
  28 void afs_put_addrlist(struct afs_addr_list *alist)
  29 {
  30         if (alist && refcount_dec_and_test(&alist->usage))
  31                 call_rcu(&alist->rcu, (rcu_callback_t)kfree);
  32 }
  33
  34 /*
  35  * Allocate an address list.
  36  */
  37 struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
  38                                          unsigned short service,
  39                                          unsigned short port)
  40 {
  41         struct afs_addr_list *alist;
  42         unsigned int i;
  43
  44         _enter("%u,%u,%u", nr, service, port);
  45
  46         alist = kzalloc(sizeof(*alist) + sizeof(alist->addrs[0]) * nr,
  47                         GFP_KERNEL);
  48         if (!alist)
  49                 return NULL;
  50
  51         refcount_set(&alist->usage, 1);
  52
  53         for (i = 0; i < nr; i++) {
  54                 struct sockaddr_rxrpc *srx = &alist->addrs[i];
  55                 srx->srx_family                 = AF_RXRPC;
  56                 srx->srx_service                = service;
  57                 srx->transport_type             = SOCK_DGRAM;
  58                 srx->transport_len              = sizeof(srx->transport.sin6);
  59                 srx->transport.sin6.sin6_family = AF_INET6;
  60                 srx->transport.sin6.sin6_port   = htons(port);
  61         }
  62
  63         return alist;
  64 }
  65
  66 /*
  67  * Parse a text string consisting of delimited addresses.
  68  */
  69 struct afs_addr_list *afs_parse_text_addrs(const char *text, size_t len,
  70                                            char delim,
  71                                            unsigned short service,
  72                                            unsigned short port)
  73 {
  74         struct afs_addr_list *alist;
  75         const char *p, *end = text + len;
  76         unsigned int nr = 0;
  77
  78         _enter("%*.*s,%c", (int)len, (int)len, text, delim);
  79
  80         if (!len)
  81                 return ERR_PTR(-EDESTADDRREQ);
  82
  83         if (delim == ':' && (memchr(text, ',', len) || !memchr(text, '.', len)))
  84                 delim = ',';
  85
  86         /* Count the addresses */
  87         p = text;
  88         do {
  89                 if (!*p)
  90                         return ERR_PTR(-EINVAL);
  91                 if (*p == delim)
  92                         continue;
  93                 nr++;
  94                 if (*p == '[') {
  95                         p++;
  96                         if (p == end)
  97                                 return ERR_PTR(-EINVAL);
  98                         p = memchr(p, ']', end - p);
  99                         if (!p)
 100                                 return ERR_PTR(-EINVAL);
 101                         p++;
 102                         if (p >= end)
 103                                 break;
 104                 }
 105
 106                 p = memchr(p, delim, end - p);
 107                 if (!p)
 108                         break;
 109                 p++;
 110         } while (p < end);
 111
 112         _debug("%u/%u addresses", nr, AFS_MAX_ADDRESSES);
 113         if (nr > AFS_MAX_ADDRESSES)
 114                 nr = AFS_MAX_ADDRESSES;
 115
 116         alist = afs_alloc_addrlist(nr, service, port);
 117         if (!alist)
 118                 return ERR_PTR(-ENOMEM);
 119
 120         /* Extract the addresses */
 121         p = text;
 122         do {
 123                 struct sockaddr_rxrpc *srx = &alist->addrs[alist->nr_addrs];
 124                 char tdelim = delim;
 125
 126                 if (*p == delim) {
 127                         p++;
 128                         continue;
 129                 }
 130
 131                 if (*p == '[') {
 132                         p++;
 133                         tdelim = ']';
 134                 }
 135
 136                 if (in4_pton(p, end - p,
 137                              (u8 *)&srx->transport.sin6.sin6_addr.s6_addr32[3],
 138                              tdelim, &p)) {
 139                         srx->transport.sin6.sin6_addr.s6_addr32[0] = 0;
 140                         srx->transport.sin6.sin6_addr.s6_addr32[1] = 0;
 141                         srx->transport.sin6.sin6_addr.s6_addr32[2] = htonl(0xffff);
 142                 } else if (in6_pton(p, end - p,
 143                                     srx->transport.sin6.sin6_addr.s6_addr,
 144                                     tdelim, &p)) {
 145                         /* Nothing to do */
 146                 } else {
 147                         goto bad_address;
 148                 }
 149
 150                 if (tdelim == ']') {
 151                         if (p == end || *p != ']')
 152                                 goto bad_address;
 153                         p++;
 154                 }
 155
 156                 if (p < end) {
 157                         if (*p == '+') {
 158                                 /* Port number specification "+1234" */
 159                                 unsigned int xport = 0;
 160                                 p++;
 161                                 if (p >= end || !isdigit(*p))
 162                                         goto bad_address;
 163                                 do {
 164                                         xport *= 10;
 165                                         xport += *p - '0';
 166                                         if (xport > 65535)
 167                                                 goto bad_address;
 168                                         p++;
 169                                 } while (p < end && isdigit(*p));
 170                                 srx->transport.sin6.sin6_port = htons(xport);
 171                         } else if (*p == delim) {
 172                                 p++;
 173                         } else {
 174                                 goto bad_address;
 175                         }
 176                 }
 177
 178                 alist->nr_addrs++;
 179         } while (p < end && alist->nr_addrs < AFS_MAX_ADDRESSES);
 180
 181         _leave(" = [nr %u]", alist->nr_addrs);
 182         return alist;
 183
 184 bad_address:
 185         kfree(alist);
 186         return ERR_PTR(-EINVAL);
 187 }
 188
 189 /*
 190  * Compare old and new address lists to see if there's been any change.
 191  * - How to do this in better than O(Nlog(N)) time?
 192  *   - We don't really want to sort the address list, but would rather take the
 193  *     list as we got it so as not to undo record rotation by the DNS server.
 194  */
 195 #if 0
 196 static int afs_cmp_addr_list(const struct afs_addr_list *a1,
 197                              const struct afs_addr_list *a2)
 198 {
 199 }
 200 #endif
 201
 202 /*
 203  * Perform a DNS query for VL servers and build a up an address list.
 204  */
 205 struct afs_addr_list *afs_dns_query(struct afs_cell *cell, time64_t *_expiry)
 206 {
 207         struct afs_addr_list *alist;
 208         char *vllist = NULL;
 209         int ret;
 210
 211         _enter("%s", cell->name);
 212
 213         ret = dns_query("afsdb", cell->name, cell->name_len,
 214                         "ipv4", &vllist, _expiry);
 215         if (ret < 0)
 216                 return ERR_PTR(ret);
 217
 218         alist = afs_parse_text_addrs(vllist, strlen(vllist), ',',
 219                                      VL_SERVICE, AFS_VL_PORT);
 220         if (IS_ERR(alist)) {
 221                 kfree(vllist);
 222                 if (alist != ERR_PTR(-ENOMEM))
 223                         pr_err("Failed to parse DNS data\n");
 224                 return alist;
 225         }
 226
 227         kfree(vllist);
 228         return alist;
 229 }
 230
 231 /*
 232  * Merge an IPv4 entry into a fileserver address list.
 233  */
 234 void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
 235 {
 236         struct sockaddr_in6 *a;
 237         __be16 xport = htons(port);
 238         int i;
 239
 240         for (i = 0; i < alist->nr_ipv4; i++) {
 241                 a = &alist->addrs[i].transport.sin6;
 242                 if (xdr == a->sin6_addr.s6_addr32[3] &&
 243                     xport == a->sin6_port)
 244                         return;
 245                 if (xdr == a->sin6_addr.s6_addr32[3] &&
 246                     xport < a->sin6_port)
 247                         break;
 248                 if (xdr < a->sin6_addr.s6_addr32[3])
 249                         break;
 250         }
 251
 252         if (i < alist->nr_addrs)
 253                 memmove(alist->addrs + i + 1,
 254                         alist->addrs + i,
 255                         sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
 256
 257         a = &alist->addrs[i].transport.sin6;
 258         a->sin6_port              = xport;
 259         a->sin6_addr.s6_addr32[0] = 0;
 260         a->sin6_addr.s6_addr32[1] = 0;
 261         a->sin6_addr.s6_addr32[2] = htonl(0xffff);
 262         a->sin6_addr.s6_addr32[3] = xdr;
 263         alist->nr_ipv4++;
 264         alist->nr_addrs++;
 265 }
 266
 267 /*
 268  * Merge an IPv6 entry into a fileserver address list.
 269  */
 270 void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
 271 {
 272         struct sockaddr_in6 *a;
 273         __be16 xport = htons(port);
 274         int i, diff;
 275
 276         for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
 277                 a = &alist->addrs[i].transport.sin6;
 278                 diff = memcmp(xdr, &a->sin6_addr, 16);
 279                 if (diff == 0 &&
 280                     xport == a->sin6_port)
 281                         return;
 282                 if (diff == 0 &&
 283                     xport < a->sin6_port)
 284                         break;
 285                 if (diff < 0)
 286                         break;
 287         }
 288
 289         if (i < alist->nr_addrs)
 290                 memmove(alist->addrs + i + 1,
 291                         alist->addrs + i,
 292                         sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
 293
 294         a = &alist->addrs[i].transport.sin6;
 295         a->sin6_port              = xport;
 296         a->sin6_addr.s6_addr32[0] = xdr[0];
 297         a->sin6_addr.s6_addr32[1] = xdr[1];
 298         a->sin6_addr.s6_addr32[2] = xdr[2];
 299         a->sin6_addr.s6_addr32[3] = xdr[3];
 300         alist->nr_addrs++;
 301 }
 302
 303 /*
 304  * Get an address to try.
 305  */
 306 bool afs_iterate_addresses(struct afs_addr_cursor *ac)
 307 {
 308         _enter("%hu+%hd", ac->start, (short)ac->index);
 309
 310         if (!ac->alist)
 311                 return false;
 312
 313         if (ac->begun) {
 314                 ac->index++;
 315                 if (ac->index == ac->alist->nr_addrs)
 316                         ac->index = 0;
 317
 318                 if (ac->index == ac->start) {
 319                         ac->error = -EDESTADDRREQ;
 320                         return false;
 321                 }
 322         }
 323
 324         ac->begun = true;
 325         ac->responded = false;
 326         ac->addr = &ac->alist->addrs[ac->index];
 327         return true;
 328 }
 329
 330 /*
 331  * Release an address list cursor.
 332  */
 333 int afs_end_cursor(struct afs_addr_cursor *ac)
 334 {
 335         if (ac->responded && ac->index != ac->start)
 336                 WRITE_ONCE(ac->alist->index, ac->index);
 337
 338         afs_put_addrlist(ac->alist);
 339         ac->alist = NULL;
 340         return ac->error;
 341 }
 342
 343 /*
 344  * Set the address cursor for iterating over VL servers.
 345  */
 346 int afs_set_vl_cursor(struct afs_addr_cursor *ac, struct afs_cell *cell)
 347 {
 348         struct afs_addr_list *alist;
 349         int ret;
 350
 351         if (!rcu_access_pointer(cell->vl_addrs)) {
 352                 ret = wait_on_bit(&cell->flags, AFS_CELL_FL_NO_LOOKUP_YET,
 353                                   TASK_INTERRUPTIBLE);
 354                 if (ret < 0)
 355                         return ret;
 356
 357                 if (!rcu_access_pointer(cell->vl_addrs) &&
 358                     ktime_get_real_seconds() < cell->dns_expiry)
 359                         return cell->error;
 360         }
 361
 362         read_lock(&cell->vl_addrs_lock);
 363         alist = rcu_dereference_protected(cell->vl_addrs,
 364                                           lockdep_is_held(&cell->vl_addrs_lock));
 365         if (alist->nr_addrs > 0)
 366                 afs_get_addrlist(alist);
 367         else
 368                 alist = NULL;
 369         read_unlock(&cell->vl_addrs_lock);
 370
 371         if (!alist)
 372                 return -EDESTADDRREQ;
 373
 374         ac->alist = alist;
 375         ac->addr = NULL;
 376         ac->start = READ_ONCE(alist->index);
 377         ac->index = ac->start;
 378         ac->error = 0;
 379         ac->begun = false;
 380         return 0;
 381 }