xref: /kernel/linux/linux-5.10/fs/afs/addr_list.c (revision 8c2ecf20) 
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 */
19void 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 */
28struct 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 */
63struct 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
210inval:
211	_leave(" = -EINVAL [%s %zu %*.*s]",
212	       problem, p - text, (int)len, (int)len, text);
213	return ERR_PTR(-EINVAL);
214bad_address:
215	_leave(" = -EINVAL [%s %zu %*.*s]",
216	       problem, p - text, (int)len, (int)len, text);
217	ret = -EINVAL;
218error:
219	afs_put_addrlist(alist);
220error_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
232static 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 */
241struct 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 */
274void 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 */
315void 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 */
354bool 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
379selected:
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 */
389int 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