xref: /openbmc/linux/fs/afs/addr_list.c (revision bc05aa6e)
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 	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 	}
343 
344 	ac->addr = NULL;
345 	ac->alist = NULL;
346 	ac->begun = false;
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 }
389