1/*	$NetBSD$	*/
2
3/*
4 * Copyright (c) 1997 - 2001 Kungliga Tekniska H��gskolan
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
43ssize_t
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
71OM_uint32
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
94OM_uint32
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
125OM_uint32
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
156OM_uint32
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
186OM_uint32
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