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197c183f SF |
1 | /* |
2 | * fs/cifs/dns_resolve.c | |
3 | * | |
4 | * Copyright (c) 2007 Igor Mammedov | |
5 | * Author(s): Igor Mammedov (niallain@gmail.com) | |
6 | * Steve French (sfrench@us.ibm.com) | |
7 | * | |
8 | * Contains the CIFS DFS upcall routines used for hostname to | |
9 | * IP address translation. | |
10 | * | |
11 | * This library is free software; you can redistribute it and/or modify | |
12 | * it under the terms of the GNU Lesser General Public License as published | |
13 | * by the Free Software Foundation; either version 2.1 of the License, or | |
14 | * (at your option) any later version. | |
15 | * | |
16 | * This library is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See | |
19 | * the GNU Lesser General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU Lesser General Public License | |
22 | * along with this library; if not, write to the Free Software | |
23 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
24 | */ | |
25 | ||
26 | #include <keys/user-type.h> | |
27 | #include "dns_resolve.h" | |
28 | #include "cifsglob.h" | |
29 | #include "cifsproto.h" | |
30 | #include "cifs_debug.h" | |
31 | ||
32 | static int dns_resolver_instantiate(struct key *key, const void *data, | |
33 | size_t datalen) | |
34 | { | |
35 | int rc = 0; | |
36 | char *ip; | |
37 | ||
38 | ip = kmalloc(datalen+1, GFP_KERNEL); | |
39 | if (!ip) | |
40 | return -ENOMEM; | |
41 | ||
42 | memcpy(ip, data, datalen); | |
43 | ip[datalen] = '\0'; | |
44 | ||
45 | rcu_assign_pointer(key->payload.data, ip); | |
46 | ||
47 | return rc; | |
48 | } | |
49 | ||
50 | struct key_type key_type_dns_resolver = { | |
51 | .name = "dns_resolver", | |
52 | .def_datalen = sizeof(struct in_addr), | |
53 | .describe = user_describe, | |
54 | .instantiate = dns_resolver_instantiate, | |
55 | .match = user_match, | |
56 | }; | |
57 | ||
d09e860c SF |
58 | /* Checks if supplied name is IP address |
59 | * returns: | |
60 | * 1 - name is IP | |
61 | * 0 - name is not IP | |
62 | */ | |
63 | static int is_ip(const char *name) | |
64 | { | |
65 | int rc; | |
66 | struct sockaddr_in sin_server; | |
67 | struct sockaddr_in6 sin_server6; | |
68 | ||
69 | rc = cifs_inet_pton(AF_INET, name, | |
70 | &sin_server.sin_addr.s_addr); | |
71 | ||
72 | if (rc <= 0) { | |
73 | /* not ipv4 address, try ipv6 */ | |
74 | rc = cifs_inet_pton(AF_INET6, name, | |
75 | &sin_server6.sin6_addr.in6_u); | |
76 | if (rc > 0) | |
77 | return 1; | |
78 | } else { | |
79 | return 1; | |
80 | } | |
81 | /* we failed translating address */ | |
82 | return 0; | |
83 | } | |
197c183f SF |
84 | |
85 | /* Resolves server name to ip address. | |
86 | * input: | |
87 | * unc - server UNC | |
88 | * output: | |
89 | * *ip_addr - pointer to server ip, caller responcible for freeing it. | |
90 | * return 0 on success | |
91 | */ | |
92 | int | |
366781c1 SF |
93 | dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) |
94 | { | |
197c183f | 95 | int rc = -EAGAIN; |
d09e860c | 96 | struct key *rkey = ERR_PTR(-EAGAIN); |
197c183f | 97 | char *name; |
d09e860c | 98 | char *data = NULL; |
197c183f SF |
99 | int len; |
100 | ||
366781c1 | 101 | if (!ip_addr || !unc) |
197c183f SF |
102 | return -EINVAL; |
103 | ||
104 | /* search for server name delimiter */ | |
105 | len = strlen(unc); | |
106 | if (len < 3) { | |
55f78e17 | 107 | cFYI(1, ("%s: unc is too short: %s", __func__, unc)); |
197c183f SF |
108 | return -EINVAL; |
109 | } | |
110 | len -= 2; | |
111 | name = memchr(unc+2, '\\', len); | |
112 | if (!name) { | |
113 | cFYI(1, ("%s: probably server name is whole unc: %s", | |
55f78e17 | 114 | __func__, unc)); |
197c183f SF |
115 | } else { |
116 | len = (name - unc) - 2/* leading // */; | |
117 | } | |
118 | ||
119 | name = kmalloc(len+1, GFP_KERNEL); | |
120 | if (!name) { | |
121 | rc = -ENOMEM; | |
122 | return rc; | |
123 | } | |
124 | memcpy(name, unc+2, len); | |
125 | name[len] = 0; | |
126 | ||
d09e860c SF |
127 | if (is_ip(name)) { |
128 | cFYI(1, ("%s: it is IP, skipping dns upcall: %s", | |
129 | __func__, name)); | |
130 | data = name; | |
131 | goto skip_upcall; | |
132 | } | |
133 | ||
197c183f SF |
134 | rkey = request_key(&key_type_dns_resolver, name, ""); |
135 | if (!IS_ERR(rkey)) { | |
d09e860c | 136 | data = rkey->payload.data; |
d09e860c SF |
137 | } else { |
138 | cERROR(1, ("%s: unable to resolve: %s", __func__, name)); | |
139 | goto out; | |
140 | } | |
141 | ||
142 | skip_upcall: | |
143 | if (data) { | |
144 | len = strlen(data); | |
145 | *ip_addr = kmalloc(len+1, GFP_KERNEL); | |
146 | if (*ip_addr) { | |
147 | memcpy(*ip_addr, data, len); | |
148 | (*ip_addr)[len] = '\0'; | |
5651ced3 IM |
149 | if (!IS_ERR(rkey)) |
150 | cFYI(1, ("%s: resolved: %s to %s", __func__, | |
151 | name, | |
152 | *ip_addr | |
153 | )); | |
197c183f SF |
154 | rc = 0; |
155 | } else { | |
156 | rc = -ENOMEM; | |
157 | } | |
d09e860c SF |
158 | if (!IS_ERR(rkey)) |
159 | key_put(rkey); | |
197c183f SF |
160 | } |
161 | ||
d09e860c | 162 | out: |
197c183f SF |
163 | kfree(name); |
164 | return rc; | |
165 | } | |
166 | ||
167 |