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
afs_alloc_vlserver(const char * name,size_t name_len,unsigned short port)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_flex(*vlserver, name, name_len + 1);
19 if (vlserver) {
20 refcount_set(&vlserver->ref, 1);
21 rwlock_init(&vlserver->lock);
22 init_waitqueue_head(&vlserver->probe_wq);
23 spin_lock_init(&vlserver->probe_lock);
24 vlserver->debug_id = atomic_inc_return(&debug_ids);
25 vlserver->rtt = UINT_MAX;
26 vlserver->name_len = name_len;
27 vlserver->service_id = VL_SERVICE;
28 vlserver->port = port;
29 memcpy(vlserver->name, name, name_len);
30 }
31 return vlserver;
32 }
33
afs_vlserver_rcu(struct rcu_head * rcu)34 static void afs_vlserver_rcu(struct rcu_head *rcu)
35 {
36 struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu);
37
38 afs_put_addrlist(rcu_access_pointer(vlserver->addresses),
39 afs_alist_trace_put_vlserver);
40 kfree_rcu(vlserver, rcu);
41 }
42
afs_put_vlserver(struct afs_net * net,struct afs_vlserver * vlserver)43 void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)
44 {
45 if (vlserver &&
46 refcount_dec_and_test(&vlserver->ref))
47 call_rcu(&vlserver->rcu, afs_vlserver_rcu);
48 }
49
afs_alloc_vlserver_list(unsigned int nr_servers)50 struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
51 {
52 struct afs_vlserver_list *vllist;
53
54 vllist = kzalloc_flex(*vllist, servers, nr_servers);
55 if (vllist) {
56 refcount_set(&vllist->ref, 1);
57 rwlock_init(&vllist->lock);
58 }
59
60 return vllist;
61 }
62
afs_put_vlserverlist(struct afs_net * net,struct afs_vlserver_list * vllist)63 void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)
64 {
65 if (vllist) {
66 if (refcount_dec_and_test(&vllist->ref)) {
67 int i;
68
69 for (i = 0; i < vllist->nr_servers; i++) {
70 afs_put_vlserver(net, vllist->servers[i].server);
71 }
72 kfree_rcu(vllist, rcu);
73 }
74 }
75 }
76
afs_extract_le16(const u8 ** _b)77 static u16 afs_extract_le16(const u8 **_b)
78 {
79 u16 val;
80
81 val = (u16)*(*_b)++ << 0;
82 val |= (u16)*(*_b)++ << 8;
83 return val;
84 }
85
86 /*
87 * Build a VL server address list from a DNS queried server list.
88 */
afs_extract_vl_addrs(struct afs_net * net,const u8 ** _b,const u8 * end,u8 nr_addrs,u16 port)89 static struct afs_addr_list *afs_extract_vl_addrs(struct afs_net *net,
90 const u8 **_b, const u8 *end,
91 u8 nr_addrs, u16 port)
92 {
93 struct afs_addr_list *alist;
94 const u8 *b = *_b;
95 int ret;
96
97 alist = afs_alloc_addrlist(nr_addrs);
98 if (!alist)
99 return ERR_PTR(-ENOMEM);
100 if (nr_addrs == 0)
101 return alist;
102
103 for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
104 struct dns_server_list_v1_address hdr;
105 __be32 x[4];
106
107 hdr.address_type = *b++;
108
109 switch (hdr.address_type) {
110 case DNS_ADDRESS_IS_IPV4:
111 if (end - b < 4) {
112 _leave(" = -EINVAL [short inet]");
113 ret = -EINVAL;
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 ret = -EINVAL;
127 goto error;
128 }
129 memcpy(x, b, 16);
130 ret = afs_merge_fs_addr6(net, alist, x, port);
131 if (ret < 0)
132 goto error;
133 b += 16;
134 break;
135
136 default:
137 _leave(" = -EADDRNOTAVAIL [unknown af %u]",
138 hdr.address_type);
139 ret = -EADDRNOTAVAIL;
140 goto error;
141 }
142 }
143
144 /* Start with IPv6 if available. */
145 if (alist->nr_ipv4 < alist->nr_addrs)
146 alist->preferred = alist->nr_ipv4;
147
148 *_b = b;
149 return alist;
150
151 error:
152 *_b = b;
153 afs_put_addrlist(alist, afs_alist_trace_put_parse_error);
154 return ERR_PTR(ret);
155 }
156
157 /*
158 * Build a VL server list from a DNS queried server list.
159 */
afs_extract_vlserver_list(struct afs_cell * cell,const void * buffer,size_t buffer_size)160 struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,
161 const void *buffer,
162 size_t buffer_size)
163 {
164 const struct dns_server_list_v1_header *hdr = buffer;
165 struct dns_server_list_v1_server bs;
166 struct afs_vlserver_list *vllist, *previous;
167 struct afs_addr_list *addrs;
168 struct afs_vlserver *server;
169 const u8 *b = buffer, *end = buffer + buffer_size;
170 int ret = -ENOMEM, nr_servers, i, j;
171
172 _enter("");
173
174 /* Check that it's a server list, v1 */
175 if (end - b < sizeof(*hdr) ||
176 hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||
177 hdr->hdr.version != 1) {
178 pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
179 hdr->hdr.content, hdr->hdr.version, end - b);
180 ret = -EDESTADDRREQ;
181 goto dump;
182 }
183
184 nr_servers = hdr->nr_servers;
185
186 vllist = afs_alloc_vlserver_list(nr_servers);
187 if (!vllist)
188 return ERR_PTR(-ENOMEM);
189
190 vllist->source = (hdr->source < NR__dns_record_source) ?
191 hdr->source : NR__dns_record_source;
192 vllist->status = (hdr->status < NR__dns_lookup_status) ?
193 hdr->status : NR__dns_lookup_status;
194
195 read_lock(&cell->vl_servers_lock);
196 previous = afs_get_vlserverlist(
197 rcu_dereference_protected(cell->vl_servers,
198 lockdep_is_held(&cell->vl_servers_lock)));
199 read_unlock(&cell->vl_servers_lock);
200
201 b += sizeof(*hdr);
202 while (end - b >= sizeof(bs)) {
203 int nlen;
204
205 bs.name_len = afs_extract_le16(&b);
206 bs.priority = afs_extract_le16(&b);
207 bs.weight = afs_extract_le16(&b);
208 bs.port = afs_extract_le16(&b);
209 bs.source = *b++;
210 bs.status = *b++;
211 bs.protocol = *b++;
212 bs.nr_addrs = *b++;
213
214 nlen = min3(bs.name_len, end - b, 255);
215
216 _debug("extract %u %u %u %u %u %u %*.*s",
217 bs.name_len, bs.priority, bs.weight,
218 bs.port, bs.protocol, bs.nr_addrs,
219 bs.name_len, nlen, b);
220
221 if (end - b < bs.name_len)
222 break;
223
224 ret = -EPROTONOSUPPORT;
225 if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
226 bs.protocol = DNS_SERVER_PROTOCOL_UDP;
227 } else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
228 _leave(" = [proto %u]", bs.protocol);
229 goto error;
230 }
231
232 if (bs.port == 0)
233 bs.port = AFS_VL_PORT;
234 if (bs.source > NR__dns_record_source)
235 bs.source = NR__dns_record_source;
236 if (bs.status > NR__dns_lookup_status)
237 bs.status = NR__dns_lookup_status;
238
239 /* See if we can update an old server record */
240 server = NULL;
241 for (i = 0; i < previous->nr_servers; i++) {
242 struct afs_vlserver *p = previous->servers[i].server;
243
244 if (p->name_len == bs.name_len &&
245 p->port == bs.port &&
246 strncasecmp(b, p->name, bs.name_len) == 0) {
247 server = afs_get_vlserver(p);
248 break;
249 }
250 }
251
252 if (!server) {
253 ret = -ENOMEM;
254 server = afs_alloc_vlserver(b, bs.name_len, bs.port);
255 if (!server)
256 goto error;
257 }
258
259 b += bs.name_len;
260
261 /* Extract the addresses - note that we can't skip this as we
262 * have to advance the payload pointer.
263 */
264 addrs = afs_extract_vl_addrs(cell->net, &b, end, bs.nr_addrs, bs.port);
265 if (IS_ERR(addrs)) {
266 ret = PTR_ERR(addrs);
267 goto error_2;
268 }
269
270 if (vllist->nr_servers >= nr_servers) {
271 _debug("skip %u >= %u", vllist->nr_servers, nr_servers);
272 afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);
273 afs_put_vlserver(cell->net, server);
274 continue;
275 }
276
277 addrs->source = bs.source;
278 addrs->status = bs.status;
279
280 if (addrs->nr_addrs == 0) {
281 afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);
282 if (!rcu_access_pointer(server->addresses)) {
283 afs_put_vlserver(cell->net, server);
284 continue;
285 }
286 } else {
287 struct afs_addr_list *old = addrs;
288
289 write_lock(&server->lock);
290 old = rcu_replace_pointer(server->addresses, old,
291 lockdep_is_held(&server->lock));
292 write_unlock(&server->lock);
293 afs_put_addrlist(old, afs_alist_trace_put_vlserver_old);
294 }
295
296 /* Check for duplicates in the server list */
297 for (j = 0; j < vllist->nr_servers; j++) {
298 struct afs_vlserver *s = vllist->servers[j].server;
299
300 if (s->name_len == server->name_len &&
301 s->port == server->port &&
302 strncasecmp(s->name, server->name, server->name_len) == 0) {
303 afs_put_vlserver(cell->net, server);
304 server = NULL;
305 break;
306 }
307 }
308 if (!server)
309 continue;
310
311 /* Insertion-sort by priority and weight */
312 for (j = 0; j < vllist->nr_servers; j++) {
313 if (bs.priority < vllist->servers[j].priority)
314 break; /* Lower preferable */
315 if (bs.priority == vllist->servers[j].priority &&
316 bs.weight > vllist->servers[j].weight)
317 break; /* Higher preferable */
318 }
319
320 if (j < vllist->nr_servers) {
321 memmove(vllist->servers + j + 1,
322 vllist->servers + j,
323 (vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));
324 }
325
326 clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
327
328 vllist->servers[j].priority = bs.priority;
329 vllist->servers[j].weight = bs.weight;
330 vllist->servers[j].server = server;
331 vllist->nr_servers++;
332 }
333
334 if (b != end) {
335 _debug("parse error %zd", b - end);
336 goto error;
337 }
338
339 afs_put_vlserverlist(cell->net, previous);
340 _leave(" = ok [%u]", vllist->nr_servers);
341 return vllist;
342
343 error_2:
344 afs_put_vlserver(cell->net, server);
345 error:
346 afs_put_vlserverlist(cell->net, vllist);
347 afs_put_vlserverlist(cell->net, previous);
348 dump:
349 if (ret != -ENOMEM) {
350 printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);
351 print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);
352 }
353 return ERR_PTR(ret);
354 }
355