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 if (total_len < 1 + len_len + 1) 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 (mech_len > total_len) 86 return GSS_S_BAD_MECH; 87 if (p - *str > total_len - mech_len) 88 return GSS_S_BAD_MECH; 89 if (ct_memcmp(p, 90 mech->elements, 91 mech->length) != 0) 92 return GSS_S_BAD_MECH; 93 p += mech_len; 94 *str = rk_UNCONST(p); 95 return GSS_S_COMPLETE; 96 } 97 98 OM_uint32 99 _gsskrb5_verify_header(u_char **str, 100 size_t total_len, 101 const void *type, 102 gss_OID oid) 103 { 104 OM_uint32 ret; 105 size_t len; 106 u_char *p = *str; 107 108 ret = _gssapi_verify_mech_header(str, total_len, oid); 109 if (ret) 110 return ret; 111 112 len = total_len - (*str - p); 113 114 if (len < 2) 115 return GSS_S_DEFECTIVE_TOKEN; 116 117 if (ct_memcmp (*str, type, 2) != 0) 118 return GSS_S_DEFECTIVE_TOKEN; 119 *str += 2; 120 121 return 0; 122 } 123 124 /* 125 * Remove the GSS-API wrapping from `in_token' giving `out_data. 126 * Does not copy data, so just free `in_token'. 127 */ 128 129 OM_uint32 130 _gssapi_decapsulate( 131 OM_uint32 *minor_status, 132 gss_buffer_t input_token_buffer, 133 krb5_data *out_data, 134 const gss_OID mech 135 ) 136 { 137 u_char *p; 138 OM_uint32 ret; 139 140 p = input_token_buffer->value; 141 ret = _gssapi_verify_mech_header(&p, 142 input_token_buffer->length, 143 mech); 144 if (ret) { 145 *minor_status = 0; 146 return ret; 147 } 148 149 out_data->length = input_token_buffer->length - 150 (p - (u_char *)input_token_buffer->value); 151 out_data->data = p; 152 return GSS_S_COMPLETE; 153 } 154 155 /* 156 * Remove the GSS-API wrapping from `in_token' giving `out_data. 157 * Does not copy data, so just free `in_token'. 158 */ 159 160 OM_uint32 161 _gsskrb5_decapsulate(OM_uint32 *minor_status, 162 gss_buffer_t input_token_buffer, 163 krb5_data *out_data, 164 const void *type, 165 gss_OID oid) 166 { 167 u_char *p; 168 OM_uint32 ret; 169 170 p = input_token_buffer->value; 171 ret = _gsskrb5_verify_header(&p, 172 input_token_buffer->length, 173 type, 174 oid); 175 if (ret) { 176 *minor_status = 0; 177 return ret; 178 } 179 180 out_data->length = input_token_buffer->length - 181 (p - (u_char *)input_token_buffer->value); 182 out_data->data = p; 183 return GSS_S_COMPLETE; 184 } 185 186 /* 187 * Verify padding of a gss wrapped message and return its length. 188 */ 189 190 OM_uint32 191 _gssapi_verify_pad(gss_buffer_t wrapped_token, 192 size_t datalen, 193 size_t *padlen) 194 { 195 u_char *pad; 196 size_t padlength; 197 int i; 198 199 pad = (u_char *)wrapped_token->value + wrapped_token->length; 200 padlength = pad[-1]; 201 202 if (padlength > datalen) 203 return GSS_S_BAD_MECH; 204 205 for (i = padlength; i > 0 && *--pad == padlength; i--) 206 ; 207 if (i != 0) 208 return GSS_S_BAD_MIC; 209 210 *padlen = padlength; 211 212 return 0; 213 } 214