Commit | Line | Data |
---|---|---|
0a5143f2 DH |
1 | /* AFS vlserver list management. |
2 | * | |
3 | * Copyright (C) 2018 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 License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/kernel.h> | |
13 | #include <linux/slab.h> | |
14 | #include "internal.h" | |
15 | ||
16 | struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len, | |
17 | unsigned short port) | |
18 | { | |
19 | struct afs_vlserver *vlserver; | |
20 | ||
21 | vlserver = kzalloc(struct_size(vlserver, name, name_len + 1), | |
22 | GFP_KERNEL); | |
23 | if (vlserver) { | |
24 | atomic_set(&vlserver->usage, 1); | |
25 | rwlock_init(&vlserver->lock); | |
3bf0fb6f DH |
26 | init_waitqueue_head(&vlserver->probe_wq); |
27 | spin_lock_init(&vlserver->probe_lock); | |
0a5143f2 DH |
28 | vlserver->name_len = name_len; |
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 | kfree_rcu(vlserver, rcu); | |
41 | } | |
42 | ||
43 | void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver) | |
44 | { | |
45 | if (vlserver) { | |
46 | unsigned int u = atomic_dec_return(&vlserver->usage); | |
47 | //_debug("VL PUT %p{%u}", vlserver, u); | |
48 | ||
49 | if (u == 0) | |
50 | call_rcu(&vlserver->rcu, afs_vlserver_rcu); | |
51 | } | |
52 | } | |
53 | ||
54 | struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers) | |
55 | { | |
56 | struct afs_vlserver_list *vllist; | |
57 | ||
58 | vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL); | |
59 | if (vllist) { | |
60 | atomic_set(&vllist->usage, 1); | |
61 | rwlock_init(&vllist->lock); | |
62 | } | |
63 | ||
64 | return vllist; | |
65 | } | |
66 | ||
67 | void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist) | |
68 | { | |
69 | if (vllist) { | |
70 | unsigned int u = atomic_dec_return(&vllist->usage); | |
71 | ||
72 | //_debug("VLLS PUT %p{%u}", vllist, u); | |
73 | if (u == 0) { | |
74 | int i; | |
75 | ||
76 | for (i = 0; i < vllist->nr_servers; i++) { | |
77 | afs_put_vlserver(net, vllist->servers[i].server); | |
78 | } | |
79 | kfree_rcu(vllist, rcu); | |
80 | } | |
81 | } | |
82 | } | |
83 | ||
84 | static u16 afs_extract_le16(const u8 **_b) | |
85 | { | |
86 | u16 val; | |
87 | ||
88 | val = (u16)*(*_b)++ << 0; | |
89 | val |= (u16)*(*_b)++ << 8; | |
90 | return val; | |
91 | } | |
92 | ||
93 | /* | |
94 | * Build a VL server address list from a DNS queried server list. | |
95 | */ | |
96 | static struct afs_addr_list *afs_extract_vl_addrs(const u8 **_b, const u8 *end, | |
97 | u8 nr_addrs, u16 port) | |
98 | { | |
99 | struct afs_addr_list *alist; | |
100 | const u8 *b = *_b; | |
101 | int ret = -EINVAL; | |
102 | ||
103 | alist = afs_alloc_addrlist(nr_addrs, VL_SERVICE, port); | |
104 | if (!alist) | |
105 | return ERR_PTR(-ENOMEM); | |
106 | if (nr_addrs == 0) | |
107 | return alist; | |
108 | ||
109 | for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) { | |
110 | struct dns_server_list_v1_address hdr; | |
111 | __be32 x[4]; | |
112 | ||
113 | hdr.address_type = *b++; | |
114 | ||
115 | switch (hdr.address_type) { | |
116 | case DNS_ADDRESS_IS_IPV4: | |
117 | if (end - b < 4) { | |
118 | _leave(" = -EINVAL [short inet]"); | |
119 | goto error; | |
120 | } | |
121 | memcpy(x, b, 4); | |
122 | afs_merge_fs_addr4(alist, x[0], port); | |
123 | b += 4; | |
124 | break; | |
125 | ||
126 | case DNS_ADDRESS_IS_IPV6: | |
127 | if (end - b < 16) { | |
128 | _leave(" = -EINVAL [short inet6]"); | |
129 | goto error; | |
130 | } | |
131 | memcpy(x, b, 16); | |
132 | afs_merge_fs_addr6(alist, x, port); | |
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) | |
3bf0fb6f | 146 | alist->preferred = alist->nr_ipv4; |
0a5143f2 DH |
147 | |
148 | *_b = b; | |
149 | return alist; | |
150 | ||
151 | error: | |
152 | *_b = b; | |
153 | afs_put_addrlist(alist); | |
154 | return ERR_PTR(ret); | |
155 | } | |
156 | ||
157 | /* | |
158 | * Build a VL server list from a DNS queried server list. | |
159 | */ | |
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 | bs.name_len = afs_extract_le16(&b); | |
204 | bs.priority = afs_extract_le16(&b); | |
205 | bs.weight = afs_extract_le16(&b); | |
206 | bs.port = afs_extract_le16(&b); | |
207 | bs.source = *b++; | |
208 | bs.status = *b++; | |
209 | bs.protocol = *b++; | |
210 | bs.nr_addrs = *b++; | |
211 | ||
212 | _debug("extract %u %u %u %u %u %u %*.*s", | |
213 | bs.name_len, bs.priority, bs.weight, | |
214 | bs.port, bs.protocol, bs.nr_addrs, | |
215 | bs.name_len, bs.name_len, b); | |
216 | ||
217 | if (end - b < bs.name_len) | |
218 | break; | |
219 | ||
220 | ret = -EPROTONOSUPPORT; | |
221 | if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) { | |
222 | bs.protocol = DNS_SERVER_PROTOCOL_UDP; | |
223 | } else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) { | |
224 | _leave(" = [proto %u]", bs.protocol); | |
225 | goto error; | |
226 | } | |
227 | ||
228 | if (bs.port == 0) | |
229 | bs.port = AFS_VL_PORT; | |
230 | if (bs.source > NR__dns_record_source) | |
231 | bs.source = NR__dns_record_source; | |
232 | if (bs.status > NR__dns_lookup_status) | |
233 | bs.status = NR__dns_lookup_status; | |
234 | ||
235 | server = NULL; | |
236 | if (previous) { | |
237 | /* See if we can update an old server record */ | |
238 | for (i = 0; i < previous->nr_servers; i++) { | |
239 | struct afs_vlserver *p = previous->servers[i].server; | |
240 | ||
241 | if (p->name_len == bs.name_len && | |
242 | p->port == bs.port && | |
243 | strncasecmp(b, p->name, bs.name_len) == 0) { | |
244 | server = afs_get_vlserver(p); | |
245 | break; | |
246 | } | |
247 | } | |
248 | } | |
249 | ||
250 | if (!server) { | |
251 | ret = -ENOMEM; | |
252 | server = afs_alloc_vlserver(b, bs.name_len, bs.port); | |
253 | if (!server) | |
254 | goto error; | |
255 | } | |
256 | ||
257 | b += bs.name_len; | |
258 | ||
259 | /* Extract the addresses - note that we can't skip this as we | |
260 | * have to advance the payload pointer. | |
261 | */ | |
262 | addrs = afs_extract_vl_addrs(&b, end, bs.nr_addrs, bs.port); | |
263 | if (IS_ERR(addrs)) { | |
264 | ret = PTR_ERR(addrs); | |
265 | goto error_2; | |
266 | } | |
267 | ||
268 | if (vllist->nr_servers >= nr_servers) { | |
269 | _debug("skip %u >= %u", vllist->nr_servers, nr_servers); | |
270 | afs_put_addrlist(addrs); | |
271 | afs_put_vlserver(cell->net, server); | |
272 | continue; | |
273 | } | |
274 | ||
275 | addrs->source = bs.source; | |
276 | addrs->status = bs.status; | |
277 | ||
278 | if (addrs->nr_addrs == 0) { | |
279 | afs_put_addrlist(addrs); | |
280 | if (!rcu_access_pointer(server->addresses)) { | |
281 | afs_put_vlserver(cell->net, server); | |
282 | continue; | |
283 | } | |
284 | } else { | |
285 | struct afs_addr_list *old = addrs; | |
286 | ||
287 | write_lock(&server->lock); | |
288 | rcu_swap_protected(server->addresses, old, | |
289 | lockdep_is_held(&server->lock)); | |
290 | write_unlock(&server->lock); | |
291 | afs_put_addrlist(old); | |
292 | } | |
293 | ||
294 | ||
295 | /* TODO: Might want to check for duplicates */ | |
296 | ||
297 | /* Insertion-sort by priority and weight */ | |
298 | for (j = 0; j < vllist->nr_servers; j++) { | |
299 | if (bs.priority < vllist->servers[j].priority) | |
300 | break; /* Lower preferable */ | |
301 | if (bs.priority == vllist->servers[j].priority && | |
302 | bs.weight > vllist->servers[j].weight) | |
303 | break; /* Higher preferable */ | |
304 | } | |
305 | ||
306 | if (j < vllist->nr_servers) { | |
307 | memmove(vllist->servers + j + 1, | |
308 | vllist->servers + j, | |
309 | (vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry)); | |
310 | } | |
311 | ||
3bf0fb6f DH |
312 | clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags); |
313 | ||
0a5143f2 DH |
314 | vllist->servers[j].priority = bs.priority; |
315 | vllist->servers[j].weight = bs.weight; | |
316 | vllist->servers[j].server = server; | |
317 | vllist->nr_servers++; | |
318 | } | |
319 | ||
320 | if (b != end) { | |
321 | _debug("parse error %zd", b - end); | |
322 | goto error; | |
323 | } | |
324 | ||
325 | afs_put_vlserverlist(cell->net, previous); | |
326 | _leave(" = ok [%u]", vllist->nr_servers); | |
327 | return vllist; | |
328 | ||
329 | error_2: | |
330 | afs_put_vlserver(cell->net, server); | |
331 | error: | |
332 | afs_put_vlserverlist(cell->net, vllist); | |
333 | afs_put_vlserverlist(cell->net, previous); | |
334 | dump: | |
335 | if (ret != -ENOMEM) { | |
336 | printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer); | |
337 | print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size); | |
338 | } | |
339 | return ERR_PTR(ret); | |
340 | } |