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