1 /* 2 * Copyright (c) 1997 - 2001 Kungliga Tekniska Högskolan 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 "gsskrb5_locl.h" 35 36 /* 37 * return the length of the mechanism in token or -1 38 * (which implies that the token was bad - GSS_S_DEFECTIVE_TOKEN 39 */ 40 41 ssize_t 42 _gsskrb5_get_mech (const u_char *ptr, 43 size_t total_len, 44 const u_char **mech_ret) 45 { 46 size_t len, len_len, mech_len, foo; 47 const u_char *p = ptr; 48 int e; 49 50 if (total_len < 1) 51 return -1; 52 if (*p++ != 0x60) 53 return -1; 54 e = der_get_length (p, total_len - 1, &len, &len_len); 55 if (e || 1 + len_len + len != total_len) 56 return -1; 57 p += len_len; 58 if (*p++ != 0x06) 59 return -1; 60 e = der_get_length (p, total_len - 1 - len_len - 1, 61 &mech_len, &foo); 62 if (e) 63 return -1; 64 p += foo; 65 *mech_ret = p; 66 return mech_len; 67 } 68 69 OM_uint32 70 _gssapi_verify_mech_header(u_char **str, 71 size_t total_len, 72 gss_OID mech) 73 { 74 const u_char *p; 75 ssize_t mech_len; 76 77 mech_len = _gsskrb5_get_mech (*str, total_len, &p); 78 if (mech_len < 0) 79 return GSS_S_DEFECTIVE_TOKEN; 80 81 if (mech_len != mech->length) 82 return GSS_S_BAD_MECH; 83 if (ct_memcmp(p, 84 mech->elements, 85 mech->length) != 0) 86 return GSS_S_BAD_MECH; 87 p += mech_len; 88 *str = rk_UNCONST(p); 89 return GSS_S_COMPLETE; 90 } 91 92 OM_uint32 93 _gsskrb5_verify_header(u_char **str, 94 size_t total_len, 95 const void *type, 96 gss_OID oid) 97 { 98 OM_uint32 ret; 99 size_t len; 100 u_char *p = *str; 101 102 ret = _gssapi_verify_mech_header(str, total_len, oid); 103 if (ret) 104 return ret; 105 106 len = total_len - (*str - p); 107 108 if (len < 2) 109 return GSS_S_DEFECTIVE_TOKEN; 110 111 if (ct_memcmp (*str, type, 2) != 0) 112 return GSS_S_DEFECTIVE_TOKEN; 113 *str += 2; 114 115 return 0; 116 } 117 118 /* 119 * Remove the GSS-API wrapping from `in_token' giving `out_data. 120 * Does not copy data, so just free `in_token'. 121 */ 122 123 OM_uint32 124 _gssapi_decapsulate( 125 OM_uint32 *minor_status, 126 gss_buffer_t input_token_buffer, 127 krb5_data *out_data, 128 const gss_OID mech 129 ) 130 { 131 u_char *p; 132 OM_uint32 ret; 133 134 p = input_token_buffer->value; 135 ret = _gssapi_verify_mech_header(&p, 136 input_token_buffer->length, 137 mech); 138 if (ret) { 139 *minor_status = 0; 140 return ret; 141 } 142 143 out_data->length = input_token_buffer->length - 144 (p - (u_char *)input_token_buffer->value); 145 out_data->data = p; 146 return GSS_S_COMPLETE; 147 } 148 149 /* 150 * Remove the GSS-API wrapping from `in_token' giving `out_data. 151 * Does not copy data, so just free `in_token'. 152 */ 153 154 OM_uint32 155 _gsskrb5_decapsulate(OM_uint32 *minor_status, 156 gss_buffer_t input_token_buffer, 157 krb5_data *out_data, 158 const void *type, 159 gss_OID oid) 160 { 161 u_char *p; 162 OM_uint32 ret; 163 164 p = input_token_buffer->value; 165 ret = _gsskrb5_verify_header(&p, 166 input_token_buffer->length, 167 type, 168 oid); 169 if (ret) { 170 *minor_status = 0; 171 return ret; 172 } 173 174 out_data->length = input_token_buffer->length - 175 (p - (u_char *)input_token_buffer->value); 176 out_data->data = p; 177 return GSS_S_COMPLETE; 178 } 179 180 /* 181 * Verify padding of a gss wrapped message and return its length. 182 */ 183 184 OM_uint32 185 _gssapi_verify_pad(gss_buffer_t wrapped_token, 186 size_t datalen, 187 size_t *padlen) 188 { 189 u_char *pad; 190 size_t padlength; 191 int i; 192 193 pad = (u_char *)wrapped_token->value + wrapped_token->length - 1; 194 padlength = *pad; 195 196 if (padlength > datalen) 197 return GSS_S_BAD_MECH; 198 199 for (i = padlength; i > 0 && *pad == padlength; i--, pad--) 200 ; 201 if (i != 0) 202 return GSS_S_BAD_MIC; 203 204 *padlen = padlength; 205 206 return 0; 207 } 208