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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
0a5143f2 DH |
2 | /* AFS vlserver list management. |
3 | * | |
4 | * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
0a5143f2 DH |
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 | ||
17 | vlserver = kzalloc(struct_size(vlserver, name, name_len + 1), | |
18 | GFP_KERNEL); | |
19 | if (vlserver) { | |
c56f9ec8 | 20 | refcount_set(&vlserver->ref, 1); |
0a5143f2 | 21 | rwlock_init(&vlserver->lock); |
3bf0fb6f DH |
22 | init_waitqueue_head(&vlserver->probe_wq); |
23 | spin_lock_init(&vlserver->probe_lock); | |
b95b3094 | 24 | vlserver->rtt = UINT_MAX; |
0a5143f2 DH |
25 | vlserver->name_len = name_len; |
26 | vlserver->port = port; | |
27 | memcpy(vlserver->name, name, name_len); | |
28 | } | |
29 | return vlserver; | |
30 | } | |
31 | ||
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 | ||
40 | void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver) | |
41 | { | |
c56f9ec8 DH |
42 | if (vlserver && |
43 | refcount_dec_and_test(&vlserver->ref)) | |
44 | call_rcu(&vlserver->rcu, afs_vlserver_rcu); | |
0a5143f2 DH |
45 | } |
46 | ||
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) { | |
c56f9ec8 | 53 | refcount_set(&vllist->ref, 1); |
0a5143f2 DH |
54 | rwlock_init(&vllist->lock); |
55 | } | |
56 | ||
57 | return vllist; | |
58 | } | |
59 | ||
60 | void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist) | |
61 | { | |
62 | if (vllist) { | |
c56f9ec8 | 63 | if (refcount_dec_and_test(&vllist->ref)) { |
0a5143f2 DH |
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 | ||
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 | */ | |
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) | |
3bf0fb6f | 136 | alist->preferred = alist->nr_ipv4; |
0a5143f2 DH |
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 | */ | |
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 | ||
ca1cbbdc | 225 | /* See if we can update an old server record */ |
0a5143f2 | 226 | server = NULL; |
ca1cbbdc DH |
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; | |
0a5143f2 DH |
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); | |
62860da7 PM |
276 | old = rcu_replace_pointer(server->addresses, old, |
277 | lockdep_is_held(&server->lock)); | |
0a5143f2 DH |
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 | ||
3bf0fb6f DH |
300 | clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags); |
301 | ||
0a5143f2 DH |
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 | } |