1 /* $NetBSD: decapsulate.c,v 1.1.1.1 2011/04/13 18:14:45 elric Exp $ */
2
3 /*
4 * Copyright (c) 1997 - 2001 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include "gsskrb5_locl.h"
37
38 /*
39 * return the length of the mechanism in token or -1
40 * (which implies that the token was bad - GSS_S_DEFECTIVE_TOKEN
41 */
42
43 ssize_t
_gsskrb5_get_mech(const u_char * ptr,size_t total_len,const u_char ** mech_ret)44 _gsskrb5_get_mech (const u_char *ptr,
45 size_t total_len,
46 const u_char **mech_ret)
47 {
48 size_t len, len_len, mech_len, foo;
49 const u_char *p = ptr;
50 int e;
51
52 if (total_len < 1)
53 return -1;
54 if (*p++ != 0x60)
55 return -1;
56 e = der_get_length (p, total_len - 1, &len, &len_len);
57 if (e || 1 + len_len + len != total_len)
58 return -1;
59 p += len_len;
60 if (*p++ != 0x06)
61 return -1;
62 e = der_get_length (p, total_len - 1 - len_len - 1,
63 &mech_len, &foo);
64 if (e)
65 return -1;
66 p += foo;
67 *mech_ret = p;
68 return mech_len;
69 }
70
71 OM_uint32
_gssapi_verify_mech_header(u_char ** str,size_t total_len,gss_OID mech)72 _gssapi_verify_mech_header(u_char **str,
73 size_t total_len,
74 gss_OID mech)
75 {
76 const u_char *p;
77 ssize_t mech_len;
78
79 mech_len = _gsskrb5_get_mech (*str, total_len, &p);
80 if (mech_len < 0)
81 return GSS_S_DEFECTIVE_TOKEN;
82
83 if (mech_len != mech->length)
84 return GSS_S_BAD_MECH;
85 if (ct_memcmp(p,
86 mech->elements,
87 mech->length) != 0)
88 return GSS_S_BAD_MECH;
89 p += mech_len;
90 *str = rk_UNCONST(p);
91 return GSS_S_COMPLETE;
92 }
93
94 OM_uint32
_gsskrb5_verify_header(u_char ** str,size_t total_len,const void * type,gss_OID oid)95 _gsskrb5_verify_header(u_char **str,
96 size_t total_len,
97 const void *type,
98 gss_OID oid)
99 {
100 OM_uint32 ret;
101 size_t len;
102 u_char *p = *str;
103
104 ret = _gssapi_verify_mech_header(str, total_len, oid);
105 if (ret)
106 return ret;
107
108 len = total_len - (*str - p);
109
110 if (len < 2)
111 return GSS_S_DEFECTIVE_TOKEN;
112
113 if (ct_memcmp (*str, type, 2) != 0)
114 return GSS_S_DEFECTIVE_TOKEN;
115 *str += 2;
116
117 return 0;
118 }
119
120 /*
121 * Remove the GSS-API wrapping from `in_token' giving `out_data.
122 * Does not copy data, so just free `in_token'.
123 */
124
125 OM_uint32
_gssapi_decapsulate(OM_uint32 * minor_status,gss_buffer_t input_token_buffer,krb5_data * out_data,const gss_OID mech)126 _gssapi_decapsulate(
127 OM_uint32 *minor_status,
128 gss_buffer_t input_token_buffer,
129 krb5_data *out_data,
130 const gss_OID mech
131 )
132 {
133 u_char *p;
134 OM_uint32 ret;
135
136 p = input_token_buffer->value;
137 ret = _gssapi_verify_mech_header(&p,
138 input_token_buffer->length,
139 mech);
140 if (ret) {
141 *minor_status = 0;
142 return ret;
143 }
144
145 out_data->length = input_token_buffer->length -
146 (p - (u_char *)input_token_buffer->value);
147 out_data->data = p;
148 return GSS_S_COMPLETE;
149 }
150
151 /*
152 * Remove the GSS-API wrapping from `in_token' giving `out_data.
153 * Does not copy data, so just free `in_token'.
154 */
155
156 OM_uint32
_gsskrb5_decapsulate(OM_uint32 * minor_status,gss_buffer_t input_token_buffer,krb5_data * out_data,const void * type,gss_OID oid)157 _gsskrb5_decapsulate(OM_uint32 *minor_status,
158 gss_buffer_t input_token_buffer,
159 krb5_data *out_data,
160 const void *type,
161 gss_OID oid)
162 {
163 u_char *p;
164 OM_uint32 ret;
165
166 p = input_token_buffer->value;
167 ret = _gsskrb5_verify_header(&p,
168 input_token_buffer->length,
169 type,
170 oid);
171 if (ret) {
172 *minor_status = 0;
173 return ret;
174 }
175
176 out_data->length = input_token_buffer->length -
177 (p - (u_char *)input_token_buffer->value);
178 out_data->data = p;
179 return GSS_S_COMPLETE;
180 }
181
182 /*
183 * Verify padding of a gss wrapped message and return its length.
184 */
185
186 OM_uint32
_gssapi_verify_pad(gss_buffer_t wrapped_token,size_t datalen,size_t * padlen)187 _gssapi_verify_pad(gss_buffer_t wrapped_token,
188 size_t datalen,
189 size_t *padlen)
190 {
191 u_char *pad;
192 size_t padlength;
193 int i;
194
195 pad = (u_char *)wrapped_token->value + wrapped_token->length - 1;
196 padlength = *pad;
197
198 if (padlength > datalen)
199 return GSS_S_BAD_MECH;
200
201 for (i = padlength; i > 0 && *pad == padlength; i--, pad--)
202 ;
203 if (i != 0)
204 return GSS_S_BAD_MIC;
205
206 *padlen = padlength;
207
208 return 0;
209 }
210