fs/afs/addr_list.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Server address list management
   3  *
   4  * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/slab.h>
   9 #include <linux/ctype.h>
  10 #include <linux/dns_resolver.h>
  11 #include <linux/inet.h>
  12 #include <keys/rxrpc-type.h>
  13 #include "internal.h"
  14 #include "afs_fs.h"
  15
  16 /*
  17  * Release an address list.
  18  */
  19 void afs_put_addrlist(struct afs_addr_list *alist)
  20 {
  21         if (alist && refcount_dec_and_test(&alist->usage))
  22                 kfree_rcu(alist, rcu);
  23 }
  24
  25 /*
  26  * Allocate an address list.
  27  */
  28 struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
  29                                          unsigned short service,
  30                                          unsigned short port)
  31 {
  32         struct afs_addr_list *alist;
  33         unsigned int i;
  34
  35         _enter("%u,%u,%u", nr, service, port);
  36
  37         if (nr > AFS_MAX_ADDRESSES)
  38                 nr = AFS_MAX_ADDRESSES;
  39
  40         alist = kzalloc(struct_size(alist, addrs, nr), GFP_KERNEL);
  41         if (!alist)
  42                 return NULL;
  43
  44         refcount_set(&alist->usage, 1);
  45         alist->max_addrs = nr;
  46
  47         for (i = 0; i < nr; i++) {
  48                 struct sockaddr_rxrpc *srx = &alist->addrs[i];
  49                 srx->srx_family                 = AF_RXRPC;
  50                 srx->srx_service                = service;
  51                 srx->transport_type             = SOCK_DGRAM;
  52                 srx->transport_len              = sizeof(srx->transport.sin6);
  53                 srx->transport.sin6.sin6_family = AF_INET6;
  54                 srx->transport.sin6.sin6_port   = htons(port);
  55         }
  56
  57         return alist;
  58 }
  59
  60 /*
  61  * Parse a text string consisting of delimited addresses.
  62  */
  63 struct afs_vlserver_list *afs_parse_text_addrs(struct afs_net *net,
  64                                                const char *text, size_t len,
  65                                                char delim,
  66                                                unsigned short service,
  67                                                unsigned short port)
  68 {
  69         struct afs_vlserver_list *vllist;
  70         struct afs_addr_list *alist;
  71         const char *p, *end = text + len;
  72         const char *problem;
  73         unsigned int nr = 0;
  74         int ret = -ENOMEM;
  75
  76         _enter("%*.*s,%c", (int)len, (int)len, text, delim);
  77
  78         if (!len) {
  79                 _leave(" = -EDESTADDRREQ [empty]");
  80                 return ERR_PTR(-EDESTADDRREQ);
  81         }
  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                         problem = "nul";
  91                         goto inval;
  92                 }
  93                 if (*p == delim)
  94                         continue;
  95                 nr++;
  96                 if (*p == '[') {
  97                         p++;
  98                         if (p == end) {
  99                                 problem = "brace1";
 100                                 goto inval;
 101                         }
 102                         p = memchr(p, ']', end - p);
 103                         if (!p) {
 104                                 problem = "brace2";
 105                                 goto inval;
 106                         }
 107                         p++;
 108                         if (p >= end)
 109                                 break;
 110                 }
 111
 112                 p = memchr(p, delim, end - p);
 113                 if (!p)
 114                         break;
 115                 p++;
 116         } while (p < end);
 117
 118         _debug("%u/%u addresses", nr, AFS_MAX_ADDRESSES);
 119
 120         vllist = afs_alloc_vlserver_list(1);
 121         if (!vllist)
 122                 return ERR_PTR(-ENOMEM);
 123
 124         vllist->nr_servers = 1;
 125         vllist->servers[0].server = afs_alloc_vlserver("<dummy>", 7, AFS_VL_PORT);
 126         if (!vllist->servers[0].server)
 127                 goto error_vl;
 128
 129         alist = afs_alloc_addrlist(nr, service, AFS_VL_PORT);
 130         if (!alist)
 131                 goto error;
 132
 133         /* Extract the addresses */
 134         p = text;
 135         do {
 136                 const char *q, *stop;
 137                 unsigned int xport = port;
 138                 __be32 x[4];
 139                 int family;
 140
 141                 if (*p == delim) {
 142                         p++;
 143                         continue;
 144                 }
 145
 146                 if (*p == '[') {
 147                         p++;
 148                         q = memchr(p, ']', end - p);
 149                 } else {
 150                         for (q = p; q < end; q++)
 151                                 if (*q == '+' || *q == delim)
 152                                         break;
 153                 }
 154
 155                 if (in4_pton(p, q - p, (u8 *)&x[0], -1, &stop)) {
 156                         family = AF_INET;
 157                 } else if (in6_pton(p, q - p, (u8 *)x, -1, &stop)) {
 158                         family = AF_INET6;
 159                 } else {
 160                         problem = "family";
 161                         goto bad_address;
 162                 }
 163
 164                 p = q;
 165                 if (stop != p) {
 166                         problem = "nostop";
 167                         goto bad_address;
 168                 }
 169
 170                 if (q < end && *q == ']')
 171                         p++;
 172
 173                 if (p < end) {
 174                         if (*p == '+') {
 175                                 /* Port number specification "+1234" */
 176                                 xport = 0;
 177                                 p++;
 178                                 if (p >= end || !isdigit(*p)) {
 179                                         problem = "port";
 180                                         goto bad_address;
 181                                 }
 182                                 do {
 183                                         xport *= 10;
 184                                         xport += *p - '0';
 185                                         if (xport > 65535) {
 186                                                 problem = "pval";
 187                                                 goto bad_address;
 188                                         }
 189                                         p++;
 190                                 } while (p < end && isdigit(*p));
 191                         } else if (*p == delim) {
 192                                 p++;
 193                         } else {
 194                                 problem = "weird";
 195                                 goto bad_address;
 196                         }
 197                 }
 198
 199                 if (family == AF_INET)
 200                         afs_merge_fs_addr4(alist, x[0], xport);
 201                 else
 202                         afs_merge_fs_addr6(alist, x, xport);
 203
 204         } while (p < end);
 205
 206         rcu_assign_pointer(vllist->servers[0].server->addresses, alist);
 207         _leave(" = [nr %u]", alist->nr_addrs);
 208         return vllist;
 209
 210 inval:
 211         _leave(" = -EINVAL [%s %zu %*.*s]",
 212                problem, p - text, (int)len, (int)len, text);
 213         return ERR_PTR(-EINVAL);
 214 bad_address:
 215         _leave(" = -EINVAL [%s %zu %*.*s]",
 216                problem, p - text, (int)len, (int)len, text);
 217         ret = -EINVAL;
 218 error:
 219         afs_put_addrlist(alist);
 220 error_vl:
 221         afs_put_vlserverlist(net, vllist);
 222         return ERR_PTR(ret);
 223 }
 224
 225 /*
 226  * Compare old and new address lists to see if there's been any change.
 227  * - How to do this in better than O(Nlog(N)) time?
 228  *   - We don't really want to sort the address list, but would rather take the
 229  *     list as we got it so as not to undo record rotation by the DNS server.
 230  */
 231 #if 0
 232 static int afs_cmp_addr_list(const struct afs_addr_list *a1,
 233                              const struct afs_addr_list *a2)
 234 {
 235 }
 236 #endif
 237
 238 /*
 239  * Perform a DNS query for VL servers and build a up an address list.
 240  */
 241 struct afs_vlserver_list *afs_dns_query(struct afs_cell *cell, time64_t *_expiry)
 242 {
 243         struct afs_vlserver_list *vllist;
 244         char *result = NULL;
 245         int ret;
 246
 247         _enter("%s", cell->name);
 248
 249         ret = dns_query(cell->net->net, "afsdb", cell->name, cell->name_len,
 250                         "srv=1", &result, _expiry, true);
 251         if (ret < 0) {
 252                 _leave(" = %d [dns]", ret);
 253                 return ERR_PTR(ret);
 254         }
 255
 256         if (*_expiry == 0)
 257                 *_expiry = ktime_get_real_seconds() + 60;
 258
 259         if (ret > 1 && result[0] == 0)
 260                 vllist = afs_extract_vlserver_list(cell, result, ret);
 261         else
 262                 vllist = afs_parse_text_addrs(cell->net, result, ret, ',',
 263                                               VL_SERVICE, AFS_VL_PORT);
 264         kfree(result);
 265         if (IS_ERR(vllist) && vllist != ERR_PTR(-ENOMEM))
 266                 pr_err("Failed to parse DNS data %ld\n", PTR_ERR(vllist));
 267
 268         return vllist;
 269 }
 270
 271 /*
 272  * Merge an IPv4 entry into a fileserver address list.
 273  */
 274 void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
 275 {
 276         struct sockaddr_rxrpc *srx;
 277         u32 addr = ntohl(xdr);
 278         int i;
 279
 280         if (alist->nr_addrs >= alist->max_addrs)
 281                 return;
 282
 283         for (i = 0; i < alist->nr_ipv4; i++) {
 284                 struct sockaddr_in *a = &alist->addrs[i].transport.sin;
 285                 u32 a_addr = ntohl(a->sin_addr.s_addr);
 286                 u16 a_port = ntohs(a->sin_port);
 287
 288                 if (addr == a_addr && port == a_port)
 289                         return;
 290                 if (addr == a_addr && port < a_port)
 291                         break;
 292                 if (addr < a_addr)
 293                         break;
 294         }
 295
 296         if (i < alist->nr_addrs)
 297                 memmove(alist->addrs + i + 1,
 298                         alist->addrs + i,
 299                         sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
 300
 301         srx = &alist->addrs[i];
 302         srx->srx_family = AF_RXRPC;
 303         srx->transport_type = SOCK_DGRAM;
 304         srx->transport_len = sizeof(srx->transport.sin);
 305         srx->transport.sin.sin_family = AF_INET;
 306         srx->transport.sin.sin_port = htons(port);
 307         srx->transport.sin.sin_addr.s_addr = xdr;
 308         alist->nr_ipv4++;
 309         alist->nr_addrs++;
 310 }
 311
 312 /*
 313  * Merge an IPv6 entry into a fileserver address list.
 314  */
 315 void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
 316 {
 317         struct sockaddr_rxrpc *srx;
 318         int i, diff;
 319
 320         if (alist->nr_addrs >= alist->max_addrs)
 321                 return;
 322
 323         for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
 324                 struct sockaddr_in6 *a = &alist->addrs[i].transport.sin6;
 325                 u16 a_port = ntohs(a->sin6_port);
 326
 327                 diff = memcmp(xdr, &a->sin6_addr, 16);
 328                 if (diff == 0 && port == a_port)
 329                         return;
 330                 if (diff == 0 && port < a_port)
 331                         break;
 332                 if (diff < 0)
 333                         break;
 334         }
 335
 336         if (i < alist->nr_addrs)
 337                 memmove(alist->addrs + i + 1,
 338                         alist->addrs + i,
 339                         sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
 340
 341         srx = &alist->addrs[i];
 342         srx->srx_family = AF_RXRPC;
 343         srx->transport_type = SOCK_DGRAM;
 344         srx->transport_len = sizeof(srx->transport.sin6);
 345         srx->transport.sin6.sin6_family = AF_INET6;
 346         srx->transport.sin6.sin6_port = htons(port);
 347         memcpy(&srx->transport.sin6.sin6_addr, xdr, 16);
 348         alist->nr_addrs++;
 349 }
 350
 351 /*
 352  * Get an address to try.
 353  */
 354 bool afs_iterate_addresses(struct afs_addr_cursor *ac)
 355 {
 356         unsigned long set, failed;
 357         int index;
 358
 359         if (!ac->alist)
 360                 return false;
 361
 362         set = ac->alist->responded;
 363         failed = ac->alist->failed;
 364         _enter("%lx-%lx-%lx,%d", set, failed, ac->tried, ac->index);
 365
 366         ac->nr_iterations++;
 367
 368         set &= ~(failed | ac->tried);
 369
 370         if (!set)
 371                 return false;
 372
 373         index = READ_ONCE(ac->alist->preferred);
 374         if (test_bit(index, &set))
 375                 goto selected;
 376
 377         index = __ffs(set);
 378
 379 selected:
 380         ac->index = index;
 381         set_bit(index, &ac->tried);
 382         ac->responded = false;
 383         return true;
 384 }
 385
 386 /*
 387  * Release an address list cursor.
 388  */
 389 int afs_end_cursor(struct afs_addr_cursor *ac)
 390 {
 391         struct afs_addr_list *alist;
 392
 393         alist = ac->alist;
 394         if (alist) {
 395                 if (ac->responded &&
 396                     ac->index != alist->preferred &&
 397                     test_bit(ac->alist->preferred, &ac->tried))
 398                         WRITE_ONCE(alist->preferred, ac->index);
 399                 afs_put_addrlist(alist);
 400                 ac->alist = NULL;
 401         }
 402
 403         return ac->error;
 404 }