1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS vlserver list management.
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include "internal.h"
11
12 struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
13 unsigned short port)
14 {
15 struct afs_vlserver *vlserver;
16 static atomic_t debug_ids;
17
18 vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
19 GFP_KERNEL);
20 if (vlserver) {
21 refcount_set(&vlserver->ref, 1);
22 rwlock_init(&vlserver->lock);
23 init_waitqueue_head(&vlserver->probe_wq);
24 spin_lock_init(&vlserver->probe_lock);
25 vlserver->debug_id = atomic_inc_return(&debug_ids);
26 vlserver->rtt = UINT_MAX;
27 vlserver->name_len = name_len;
28 vlserver->service_id = VL_SERVICE;
29 vlserver->port = port;
30 memcpy(vlserver->name, name, name_len);
31 }
32 return vlserver;
33 }
34
35 static void afs_vlserver_rcu(struct rcu_head *rcu)
36 {
37 struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu);
38
39 afs_put_addrlist(rcu_access_pointer(vlserver->addresses),
40 afs_alist_trace_put_vlserver);
41 kfree_rcu(vlserver, rcu);
42 }
43
44 void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)
45 {
46 if (vlserver &&
47 refcount_dec_and_test(&vlserver->ref))
48 call_rcu(&vlserver->rcu, afs_vlserver_rcu);
49 }
50
51 struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
52 {
53 struct afs_vlserver_list *vllist;
54
55 vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);
56 if (vllist) {
57 refcount_set(&vllist->ref, 1);
58 rwlock_init(&vllist->lock);
59 }
60
61 return vllist;
62 }
63
64 void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)
65 {
66 if (vllist) {
67 if (refcount_dec_and_test(&vllist->ref)) {
68 int i;
69
70 for (i = 0; i < vllist->nr_servers; i++) {
71 afs_put_vlserver(net, vllist->servers[i].server);
72 }
73 kfree_rcu(vllist, rcu);
74 }
75 }
76 }
77
78 static u16 afs_extract_le16(const u8 **_b)
79 {
80 u16 val;
81
82 val = (u16)*(*_b)++ << 0;
83 val |= (u16)*(*_b)++ << 8;
84 return val;
85 }
86
87 /*
88 * Build a VL server address list from a DNS queried server list.
89 */
90 static struct afs_addr_list *afs_extract_vl_addrs(struct afs_net *net,
91 const u8 **_b, const u8 *end,
92 u8 nr_addrs, u16 port)
93 {
94 struct afs_addr_list *alist;
95 const u8 *b = *_b;
96 int ret = -EINVAL;
97
98 alist = afs_alloc_addrlist(nr_addrs);
99 if (!alist)
100 return ERR_PTR(-ENOMEM);
101 if (nr_addrs == 0)
102 return alist;
103
104 for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
105 struct dns_server_list_v1_address hdr;
106 __be32 x[4];
107
108 hdr.address_type = *b++;
109
110 switch (hdr.address_type) {
111 case DNS_ADDRESS_IS_IPV4:
112 if (end - b < 4) {
113 _leave(" = -EINVAL [short inet]");
114 goto error;
115 }
116 memcpy(x, b, 4);
117 ret = afs_merge_fs_addr4(net, alist, x[0], port);
118 if (ret < 0)
119 goto error;
120 b += 4;
121 break;
122
123 case DNS_ADDRESS_IS_IPV6:
124 if (end - b < 16) {
125 _leave(" = -EINVAL [short inet6]");
126 goto error;
127 }
128 memcpy(x, b, 16);
129 ret = afs_merge_fs_addr6(net, alist, x, port);
130 if (ret < 0)
131 goto error;
132 b += 16;
133 break;
134
135 default:
136 _leave(" = -EADDRNOTAVAIL [unknown af %u]",
137 hdr.address_type);
138 ret = -EADDRNOTAVAIL;
139 goto error;
140 }
141 }
142
143 /* Start with IPv6 if available. */
144 if (alist->nr_ipv4 < alist->nr_addrs)
145 alist->preferred = alist->nr_ipv4;
146
147 *_b = b;
148 return alist;
149
150 error:
151 *_b = b;
152 afs_put_addrlist(alist, afs_alist_trace_put_parse_error);
153 return ERR_PTR(ret);
154 }
155
156 /*
157 * Build a VL server list from a DNS queried server list.
158 */
159 struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,
160 const void *buffer,
161 size_t buffer_size)
162 {
163 const struct dns_server_list_v1_header *hdr = buffer;
164 struct dns_server_list_v1_server bs;
165 struct afs_vlserver_list *vllist, *previous;
166 struct afs_addr_list *addrs;
167 struct afs_vlserver *server;
168 const u8 *b = buffer, *end = buffer + buffer_size;
169 int ret = -ENOMEM, nr_servers, i, j;
170
171 _enter("");
172
173 /* Check that it's a server list, v1 */
174 if (end - b < sizeof(*hdr) ||
175 hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||
176 hdr->hdr.version != 1) {
177 pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
178 hdr->hdr.content, hdr->hdr.version, end - b);
179 ret = -EDESTADDRREQ;
180 goto dump;
181 }
182
183 nr_servers = hdr->nr_servers;
184
185 vllist = afs_alloc_vlserver_list(nr_servers);
186 if (!vllist)
187 return ERR_PTR(-ENOMEM);
188
189 vllist->source = (hdr->source < NR__dns_record_source) ?
190 hdr->source : NR__dns_record_source;
191 vllist->status = (hdr->status < NR__dns_lookup_status) ?
192 hdr->status : NR__dns_lookup_status;
193
194 read_lock(&cell->vl_servers_lock);
195 previous = afs_get_vlserverlist(
196 rcu_dereference_protected(cell->vl_servers,
197 lockdep_is_held(&cell->vl_servers_lock)));
198 read_unlock(&cell->vl_servers_lock);
199
200 b += sizeof(*hdr);
201 while (end - b >= sizeof(bs)) {
202 bs.name_len = afs_extract_le16(&b);
203 bs.priority = afs_extract_le16(&b);
204 bs.weight = afs_extract_le16(&b);
205 bs.port = afs_extract_le16(&b);
206 bs.source = *b++;
207 bs.status = *b++;
208 bs.protocol = *b++;
209 bs.nr_addrs = *b++;
210
211 _debug("extract %u %u %u %u %u %u %*.*s",
212 bs.name_len, bs.priority, bs.weight,
213 bs.port, bs.protocol, bs.nr_addrs,
214 bs.name_len, bs.name_len, b);
215
216 if (end - b < bs.name_len)
217 break;
218
219 ret = -EPROTONOSUPPORT;
220 if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
221 bs.protocol = DNS_SERVER_PROTOCOL_UDP;
222 } else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
223 _leave(" = [proto %u]", bs.protocol);
224 goto error;
225 }
226
227 if (bs.port == 0)
228 bs.port = AFS_VL_PORT;
229 if (bs.source > NR__dns_record_source)
230 bs.source = NR__dns_record_source;
231 if (bs.status > NR__dns_lookup_status)
232 bs.status = NR__dns_lookup_status;
233
234 /* See if we can update an old server record */
235 server = NULL;
236 for (i = 0; i < previous->nr_servers; i++) {
237 struct afs_vlserver *p = previous->servers[i].server;
238
239 if (p->name_len == bs.name_len &&
240 p->port == bs.port &&
241 strncasecmp(b, p->name, bs.name_len) == 0) {
242 server = afs_get_vlserver(p);
243 break;
244 }
245 }
246
247 if (!server) {
248 ret = -ENOMEM;
249 server = afs_alloc_vlserver(b, bs.name_len, bs.port);
250 if (!server)
251 goto error;
252 }
253
254 b += bs.name_len;
255
256 /* Extract the addresses - note that we can't skip this as we
257 * have to advance the payload pointer.
258 */
259 addrs = afs_extract_vl_addrs(cell->net, &b, end, bs.nr_addrs, bs.port);
260 if (IS_ERR(addrs)) {
261 ret = PTR_ERR(addrs);
262 goto error_2;
263 }
264
265 if (vllist->nr_servers >= nr_servers) {
266 _debug("skip %u >= %u", vllist->nr_servers, nr_servers);
267 afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);
268 afs_put_vlserver(cell->net, server);
269 continue;
270 }
271
272 addrs->source = bs.source;
273 addrs->status = bs.status;
274
275 if (addrs->nr_addrs == 0) {
276 afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);
277 if (!rcu_access_pointer(server->addresses)) {
278 afs_put_vlserver(cell->net, server);
279 continue;
280 }
281 } else {
282 struct afs_addr_list *old = addrs;
283
284 write_lock(&server->lock);
285 old = rcu_replace_pointer(server->addresses, old,
286 lockdep_is_held(&server->lock));
287 write_unlock(&server->lock);
288 afs_put_addrlist(old, afs_alist_trace_put_vlserver_old);
289 }
290
291
292 /* TODO: Might want to check for duplicates */
293
294 /* Insertion-sort by priority and weight */
295 for (j = 0; j < vllist->nr_servers; j++) {
296 if (bs.priority < vllist->servers[j].priority)
297 break; /* Lower preferable */
298 if (bs.priority == vllist->servers[j].priority &&
299 bs.weight > vllist->servers[j].weight)
300 break; /* Higher preferable */
301 }
302
303 if (j < vllist->nr_servers) {
304 memmove(vllist->servers + j + 1,
305 vllist->servers + j,
306 (vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));
307 }
308
309 clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
310
311 vllist->servers[j].priority = bs.priority;
312 vllist->servers[j].weight = bs.weight;
313 vllist->servers[j].server = server;
314 vllist->nr_servers++;
315 }
316
317 if (b != end) {
318 _debug("parse error %zd", b - end);
319 goto error;
320 }
321
322 afs_put_vlserverlist(cell->net, previous);
323 _leave(" = ok [%u]", vllist->nr_servers);
324 return vllist;
325
326 error_2:
327 afs_put_vlserver(cell->net, server);
328 error:
329 afs_put_vlserverlist(cell->net, vllist);
330 afs_put_vlserverlist(cell->net, previous);
331 dump:
332 if (ret != -ENOMEM) {
333 printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);
334 print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);
335 }
336 return ERR_PTR(ret);
337 }
338
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