1 /* 2 * Copyright (c) 1997 - 2001 Kungliga Tekniska H�gskolan 3 * (Royal Institute of Technology, Stockholm, Sweden). 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * 3. Neither the name of the Institute nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include "krb5/gsskrb5_locl.h" 35 36 RCSID("$Id: decapsulate.c 18334 2006-10-07 22:16:04Z lha $"); 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 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 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 (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 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 (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 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 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 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