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8b2a464c DH |
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 | ||
bf99a53c DH |
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)) | |
8b2a464c DH |
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 | ||
d2ddc776 DH |
231 | /* |
232 | * Merge an IPv4 entry into a fileserver address list. | |
233 | */ | |
bf99a53c | 234 | void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port) |
d2ddc776 DH |
235 | { |
236 | struct sockaddr_in6 *a; | |
bf99a53c | 237 | __be16 xport = htons(port); |
d2ddc776 DH |
238 | int i; |
239 | ||
240 | for (i = 0; i < alist->nr_ipv4; i++) { | |
241 | a = &alist->addrs[i].transport.sin6; | |
bf99a53c DH |
242 | if (xdr == a->sin6_addr.s6_addr32[3] && |
243 | xport == a->sin6_port) | |
d2ddc776 | 244 | return; |
bf99a53c DH |
245 | if (xdr == a->sin6_addr.s6_addr32[3] && |
246 | xport < a->sin6_port) | |
247 | break; | |
d2ddc776 DH |
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; | |
bf99a53c | 258 | a->sin6_port = xport; |
d2ddc776 DH |
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 | ||
bf99a53c DH |
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 | ||
8b2a464c DH |
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 | { | |
61b3c8ca DH |
335 | struct afs_addr_list *alist; |
336 | ||
337 | alist = ac->alist; | |
338 | if (alist) { | |
339 | if (ac->responded && ac->index != ac->start) | |
340 | WRITE_ONCE(alist->index, ac->index); | |
341 | afs_put_addrlist(alist); | |
342 | } | |
8b2a464c | 343 | |
61b3c8ca | 344 | ac->addr = NULL; |
8b2a464c | 345 | ac->alist = NULL; |
61b3c8ca | 346 | ac->begun = false; |
8b2a464c DH |
347 | return ac->error; |
348 | } | |
349 | ||
350 | /* | |
351 | * Set the address cursor for iterating over VL servers. | |
352 | */ | |
353 | int afs_set_vl_cursor(struct afs_addr_cursor *ac, struct afs_cell *cell) | |
354 | { | |
355 | struct afs_addr_list *alist; | |
356 | int ret; | |
357 | ||
358 | if (!rcu_access_pointer(cell->vl_addrs)) { | |
359 | ret = wait_on_bit(&cell->flags, AFS_CELL_FL_NO_LOOKUP_YET, | |
360 | TASK_INTERRUPTIBLE); | |
361 | if (ret < 0) | |
362 | return ret; | |
363 | ||
364 | if (!rcu_access_pointer(cell->vl_addrs) && | |
365 | ktime_get_real_seconds() < cell->dns_expiry) | |
366 | return cell->error; | |
367 | } | |
368 | ||
369 | read_lock(&cell->vl_addrs_lock); | |
370 | alist = rcu_dereference_protected(cell->vl_addrs, | |
371 | lockdep_is_held(&cell->vl_addrs_lock)); | |
372 | if (alist->nr_addrs > 0) | |
373 | afs_get_addrlist(alist); | |
374 | else | |
375 | alist = NULL; | |
376 | read_unlock(&cell->vl_addrs_lock); | |
377 | ||
378 | if (!alist) | |
379 | return -EDESTADDRREQ; | |
380 | ||
381 | ac->alist = alist; | |
382 | ac->addr = NULL; | |
383 | ac->start = READ_ONCE(alist->index); | |
384 | ac->index = ac->start; | |
385 | ac->error = 0; | |
386 | ac->begun = false; | |
387 | return 0; | |
388 | } |