1 /*
2 * fs/cifs/cifs_spnego.c -- SPNEGO upcall management for CIFS
3 *
4 * Copyright (c) 2007 Red Hat, Inc.
5 * Author(s): Jeff Layton (jlayton@redhat.com)
6 *
7 * This library is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Lesser General Public License as published
9 * by the Free Software Foundation; either version 2.1 of the License, or
10 * (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
15 * the GNU Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public License
18 * along with this library; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21
22 #include <linux/list.h>
23 #include <linux/slab.h>
24 #include <linux/string.h>
25 #include <keys/user-type.h>
26 #include <linux/key-type.h>
27 #include <linux/keyctl.h>
28 #include <linux/inet.h>
29 #include "cifsglob.h"
30 #include "cifs_spnego.h"
31 #include "cifs_debug.h"
32 #include "cifsproto.h"
33 static const struct cred *spnego_cred;
34
35 /* create a new cifs key */
36 static int
cifs_spnego_key_instantiate(struct key * key,struct key_preparsed_payload * prep)37 cifs_spnego_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
38 {
39 char *payload;
40 int ret;
41
42 ret = -ENOMEM;
43 payload = kmemdup(prep->data, prep->datalen, GFP_KERNEL);
44 if (!payload)
45 goto error;
46
47 /* attach the data */
48 key->payload.data[0] = payload;
49 ret = 0;
50
51 error:
52 return ret;
53 }
54
55 static void
cifs_spnego_key_destroy(struct key * key)56 cifs_spnego_key_destroy(struct key *key)
57 {
58 kfree(key->payload.data[0]);
59 }
60
61
62 /*
63 * keytype for CIFS spnego keys
64 */
65 struct key_type cifs_spnego_key_type = {
66 .name = "cifs.spnego",
67 .instantiate = cifs_spnego_key_instantiate,
68 .destroy = cifs_spnego_key_destroy,
69 .describe = user_describe,
70 };
71
72 /* length of longest version string e.g. strlen("ver=0xFF") */
73 #define MAX_VER_STR_LEN 8
74
75 /* length of longest security mechanism name, eg in future could have
76 * strlen(";sec=ntlmsspi") */
77 #define MAX_MECH_STR_LEN 13
78
79 /* strlen of "host=" */
80 #define HOST_KEY_LEN 5
81
82 /* strlen of ";ip4=" or ";ip6=" */
83 #define IP_KEY_LEN 5
84
85 /* strlen of ";uid=0x" */
86 #define UID_KEY_LEN 7
87
88 /* strlen of ";creduid=0x" */
89 #define CREDUID_KEY_LEN 11
90
91 /* strlen of ";user=" */
92 #define USER_KEY_LEN 6
93
94 /* strlen of ";pid=0x" */
95 #define PID_KEY_LEN 7
96
97 /* get a key struct with a SPNEGO security blob, suitable for session setup */
98 struct key *
cifs_get_spnego_key(struct cifs_ses * sesInfo)99 cifs_get_spnego_key(struct cifs_ses *sesInfo)
100 {
101 struct TCP_Server_Info *server = cifs_ses_server(sesInfo);
102 struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
103 struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
104 char *description, *dp;
105 size_t desc_len;
106 struct key *spnego_key;
107 const char *hostname = server->hostname;
108 const struct cred *saved_cred;
109
110 /* length of fields (with semicolons): ver=0xyz ip4=ipaddress
111 host=hostname sec=mechanism uid=0xFF user=username */
112 desc_len = MAX_VER_STR_LEN +
113 HOST_KEY_LEN + strlen(hostname) +
114 IP_KEY_LEN + INET6_ADDRSTRLEN +
115 MAX_MECH_STR_LEN +
116 UID_KEY_LEN + (sizeof(uid_t) * 2) +
117 CREDUID_KEY_LEN + (sizeof(uid_t) * 2) +
118 PID_KEY_LEN + (sizeof(pid_t) * 2) + 1;
119
120 if (sesInfo->user_name)
121 desc_len += USER_KEY_LEN + strlen(sesInfo->user_name);
122
123 spnego_key = ERR_PTR(-ENOMEM);
124 description = kzalloc(desc_len, GFP_KERNEL);
125 if (description == NULL)
126 goto out;
127
128 dp = description;
129 /* start with version and hostname portion of UNC string */
130 spnego_key = ERR_PTR(-EINVAL);
131 sprintf(dp, "ver=0x%x;host=%s;", CIFS_SPNEGO_UPCALL_VERSION,
132 hostname);
133 dp = description + strlen(description);
134
135 /* add the server address */
136 if (server->dstaddr.ss_family == AF_INET)
137 sprintf(dp, "ip4=%pI4", &sa->sin_addr);
138 else if (server->dstaddr.ss_family == AF_INET6)
139 sprintf(dp, "ip6=%pI6", &sa6->sin6_addr);
140 else
141 goto out;
142
143 dp = description + strlen(description);
144
145 /* for now, only sec=krb5 and sec=mskrb5 are valid */
146 if (server->sec_kerberos)
147 sprintf(dp, ";sec=krb5");
148 else if (server->sec_mskerberos)
149 sprintf(dp, ";sec=mskrb5");
150 else {
151 cifs_dbg(VFS, "unknown or missing server auth type, use krb5\n");
152 sprintf(dp, ";sec=krb5");
153 }
154
155 dp = description + strlen(description);
156 sprintf(dp, ";uid=0x%x",
157 from_kuid_munged(&init_user_ns, sesInfo->linux_uid));
158
159 dp = description + strlen(description);
160 sprintf(dp, ";creduid=0x%x",
161 from_kuid_munged(&init_user_ns, sesInfo->cred_uid));
162
163 if (sesInfo->user_name) {
164 dp = description + strlen(description);
165 sprintf(dp, ";user=%s", sesInfo->user_name);
166 }
167
168 dp = description + strlen(description);
169 sprintf(dp, ";pid=0x%x", current->pid);
170
171 cifs_dbg(FYI, "key description = %s\n", description);
172 saved_cred = override_creds(spnego_cred);
173 spnego_key = request_key(&cifs_spnego_key_type, description, "");
174 revert_creds(saved_cred);
175
176 #ifdef CONFIG_CIFS_DEBUG2
177 if (cifsFYI && !IS_ERR(spnego_key)) {
178 struct cifs_spnego_msg *msg = spnego_key->payload.data[0];
179 cifs_dump_mem("SPNEGO reply blob:", msg->data, min(1024U,
180 msg->secblob_len + msg->sesskey_len));
181 }
182 #endif /* CONFIG_CIFS_DEBUG2 */
183
184 out:
185 kfree(description);
186 return spnego_key;
187 }
188
189 int
init_cifs_spnego(void)190 init_cifs_spnego(void)
191 {
192 struct cred *cred;
193 struct key *keyring;
194 int ret;
195
196 cifs_dbg(FYI, "Registering the %s key type\n",
197 cifs_spnego_key_type.name);
198
199 /*
200 * Create an override credential set with special thread keyring for
201 * spnego upcalls.
202 */
203
204 cred = prepare_kernel_cred(NULL);
205 if (!cred)
206 return -ENOMEM;
207
208 keyring = keyring_alloc(".cifs_spnego",
209 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
210 (KEY_POS_ALL & ~KEY_POS_SETATTR) |
211 KEY_USR_VIEW | KEY_USR_READ,
212 KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
213 if (IS_ERR(keyring)) {
214 ret = PTR_ERR(keyring);
215 goto failed_put_cred;
216 }
217
218 ret = register_key_type(&cifs_spnego_key_type);
219 if (ret < 0)
220 goto failed_put_key;
221
222 /*
223 * instruct request_key() to use this special keyring as a cache for
224 * the results it looks up
225 */
226 set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
227 cred->thread_keyring = keyring;
228 cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
229 spnego_cred = cred;
230
231 cifs_dbg(FYI, "cifs spnego keyring: %d\n", key_serial(keyring));
232 return 0;
233
234 failed_put_key:
235 key_put(keyring);
236 failed_put_cred:
237 put_cred(cred);
238 return ret;
239 }
240
241 void
exit_cifs_spnego(void)242 exit_cifs_spnego(void)
243 {
244 key_revoke(spnego_cred->thread_keyring);
245 unregister_key_type(&cifs_spnego_key_type);
246 put_cred(spnego_cred);
247 cifs_dbg(FYI, "Unregistered %s key type\n", cifs_spnego_key_type.name);
248 }
249