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cifs_spnego.c
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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 ([email protected])
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/inet.h>
28 #include "cifsglob.h"
29 #include "cifs_spnego.h"
30 #include "cifs_debug.h"
31 
32 /* create a new cifs key */
33 static int
34 cifs_spnego_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
35 {
36  char *payload;
37  int ret;
38 
39  ret = -ENOMEM;
40  payload = kmalloc(prep->datalen, GFP_KERNEL);
41  if (!payload)
42  goto error;
43 
44  /* attach the data */
45  memcpy(payload, prep->data, prep->datalen);
46  key->payload.data = payload;
47  ret = 0;
48 
49 error:
50  return ret;
51 }
52 
53 static void
54 cifs_spnego_key_destroy(struct key *key)
55 {
56  kfree(key->payload.data);
57 }
58 
59 
60 /*
61  * keytype for CIFS spnego keys
62  */
63 struct key_type cifs_spnego_key_type = {
64  .name = "cifs.spnego",
65  .instantiate = cifs_spnego_key_instantiate,
66  .match = user_match,
67  .destroy = cifs_spnego_key_destroy,
68  .describe = user_describe,
69 };
70 
71 /* length of longest version string e.g. strlen("ver=0xFF") */
72 #define MAX_VER_STR_LEN 8
73 
74 /* length of longest security mechanism name, eg in future could have
75  * strlen(";sec=ntlmsspi") */
76 #define MAX_MECH_STR_LEN 13
77 
78 /* strlen of "host=" */
79 #define HOST_KEY_LEN 5
80 
81 /* strlen of ";ip4=" or ";ip6=" */
82 #define IP_KEY_LEN 5
83 
84 /* strlen of ";uid=0x" */
85 #define UID_KEY_LEN 7
86 
87 /* strlen of ";creduid=0x" */
88 #define CREDUID_KEY_LEN 11
89 
90 /* strlen of ";user=" */
91 #define USER_KEY_LEN 6
92 
93 /* strlen of ";pid=0x" */
94 #define PID_KEY_LEN 7
95 
96 /* get a key struct with a SPNEGO security blob, suitable for session setup */
97 struct key *
98 cifs_get_spnego_key(struct cifs_ses *sesInfo)
99 {
100  struct TCP_Server_Info *server = sesInfo->server;
101  struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
102  struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
103  char *description, *dp;
104  size_t desc_len;
105  struct key *spnego_key;
106  const char *hostname = server->hostname;
107 
108  /* length of fields (with semicolons): ver=0xyz ip4=ipaddress
109  host=hostname sec=mechanism uid=0xFF user=username */
110  desc_len = MAX_VER_STR_LEN +
111  HOST_KEY_LEN + strlen(hostname) +
114  UID_KEY_LEN + (sizeof(uid_t) * 2) +
115  CREDUID_KEY_LEN + (sizeof(uid_t) * 2) +
116  PID_KEY_LEN + (sizeof(pid_t) * 2) + 1;
117 
118  if (sesInfo->user_name)
119  desc_len += USER_KEY_LEN + strlen(sesInfo->user_name);
120 
121  spnego_key = ERR_PTR(-ENOMEM);
122  description = kzalloc(desc_len, GFP_KERNEL);
123  if (description == NULL)
124  goto out;
125 
126  dp = description;
127  /* start with version and hostname portion of UNC string */
128  spnego_key = ERR_PTR(-EINVAL);
129  sprintf(dp, "ver=0x%x;host=%s;", CIFS_SPNEGO_UPCALL_VERSION,
130  hostname);
131  dp = description + strlen(description);
132 
133  /* add the server address */
134  if (server->dstaddr.ss_family == AF_INET)
135  sprintf(dp, "ip4=%pI4", &sa->sin_addr);
136  else if (server->dstaddr.ss_family == AF_INET6)
137  sprintf(dp, "ip6=%pI6", &sa6->sin6_addr);
138  else
139  goto out;
140 
141  dp = description + strlen(description);
142 
143  /* for now, only sec=krb5 and sec=mskrb5 are valid */
144  if (server->sec_kerberos)
145  sprintf(dp, ";sec=krb5");
146  else if (server->sec_mskerberos)
147  sprintf(dp, ";sec=mskrb5");
148  else
149  goto out;
150 
151  dp = description + strlen(description);
152  sprintf(dp, ";uid=0x%x", sesInfo->linux_uid);
153 
154  dp = description + strlen(description);
155  sprintf(dp, ";creduid=0x%x", sesInfo->cred_uid);
156 
157  if (sesInfo->user_name) {
158  dp = description + strlen(description);
159  sprintf(dp, ";user=%s", sesInfo->user_name);
160  }
161 
162  dp = description + strlen(description);
163  sprintf(dp, ";pid=0x%x", current->pid);
164 
165  cFYI(1, "key description = %s", description);
166  spnego_key = request_key(&cifs_spnego_key_type, description, "");
167 
168 #ifdef CONFIG_CIFS_DEBUG2
169  if (cifsFYI && !IS_ERR(spnego_key)) {
170  struct cifs_spnego_msg *msg = spnego_key->payload.data;
171  cifs_dump_mem("SPNEGO reply blob:", msg->data, min(1024U,
172  msg->secblob_len + msg->sesskey_len));
173  }
174 #endif /* CONFIG_CIFS_DEBUG2 */
175 
176 out:
177  kfree(description);
178  return spnego_key;
179 }