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 } 405