1 /* $OpenBSD: gss-genr.c,v 1.6 2005/10/13 22:24:31 stevesk Exp $ */ 2 3 /* 4 * Copyright (c) 2001-2003 Simon Wilkinson. 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 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #ifdef GSSAPI 30 31 #include "xmalloc.h" 32 #include "bufaux.h" 33 #include "log.h" 34 #include "ssh2.h" 35 36 #include "ssh-gss.h" 37 38 extern u_char *session_id2; 39 extern u_int session_id2_len; 40 41 /* Check that the OID in a data stream matches that in the context */ 42 int 43 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) 44 { 45 return (ctx != NULL && ctx->oid != GSS_C_NO_OID && 46 ctx->oid->length == len && 47 memcmp(ctx->oid->elements, data, len) == 0); 48 } 49 50 /* Set the contexts OID from a data stream */ 51 void 52 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) 53 { 54 if (ctx->oid != GSS_C_NO_OID) { 55 xfree(ctx->oid->elements); 56 xfree(ctx->oid); 57 } 58 ctx->oid = xmalloc(sizeof(gss_OID_desc)); 59 ctx->oid->length = len; 60 ctx->oid->elements = xmalloc(len); 61 memcpy(ctx->oid->elements, data, len); 62 } 63 64 /* Set the contexts OID */ 65 void 66 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) 67 { 68 ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length); 69 } 70 71 /* All this effort to report an error ... */ 72 void 73 ssh_gssapi_error(Gssctxt *ctxt) 74 { 75 debug("%s", ssh_gssapi_last_error(ctxt, NULL, NULL)); 76 } 77 78 char * 79 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status, 80 OM_uint32 *minor_status) 81 { 82 OM_uint32 lmin; 83 gss_buffer_desc msg = GSS_C_EMPTY_BUFFER; 84 OM_uint32 ctx; 85 Buffer b; 86 char *ret; 87 88 buffer_init(&b); 89 90 if (major_status != NULL) 91 *major_status = ctxt->major; 92 if (minor_status != NULL) 93 *minor_status = ctxt->minor; 94 95 ctx = 0; 96 /* The GSSAPI error */ 97 do { 98 gss_display_status(&lmin, ctxt->major, 99 GSS_C_GSS_CODE, GSS_C_NULL_OID, &ctx, &msg); 100 101 buffer_append(&b, msg.value, msg.length); 102 buffer_put_char(&b, '\n'); 103 104 gss_release_buffer(&lmin, &msg); 105 } while (ctx != 0); 106 107 /* The mechanism specific error */ 108 do { 109 gss_display_status(&lmin, ctxt->minor, 110 GSS_C_MECH_CODE, GSS_C_NULL_OID, &ctx, &msg); 111 112 buffer_append(&b, msg.value, msg.length); 113 buffer_put_char(&b, '\n'); 114 115 gss_release_buffer(&lmin, &msg); 116 } while (ctx != 0); 117 118 buffer_put_char(&b, '\0'); 119 ret = xmalloc(buffer_len(&b)); 120 buffer_get(&b, ret, buffer_len(&b)); 121 buffer_free(&b); 122 return (ret); 123 } 124 125 /* 126 * Initialise our GSSAPI context. We use this opaque structure to contain all 127 * of the data which both the client and server need to persist across 128 * {accept,init}_sec_context calls, so that when we do it from the userauth 129 * stuff life is a little easier 130 */ 131 void 132 ssh_gssapi_build_ctx(Gssctxt **ctx) 133 { 134 *ctx = xmalloc(sizeof (Gssctxt)); 135 (*ctx)->major = 0; 136 (*ctx)->minor = 0; 137 (*ctx)->context = GSS_C_NO_CONTEXT; 138 (*ctx)->name = GSS_C_NO_NAME; 139 (*ctx)->oid = GSS_C_NO_OID; 140 (*ctx)->creds = GSS_C_NO_CREDENTIAL; 141 (*ctx)->client = GSS_C_NO_NAME; 142 (*ctx)->client_creds = GSS_C_NO_CREDENTIAL; 143 } 144 145 /* Delete our context, providing it has been built correctly */ 146 void 147 ssh_gssapi_delete_ctx(Gssctxt **ctx) 148 { 149 OM_uint32 ms; 150 151 if ((*ctx) == NULL) 152 return; 153 if ((*ctx)->context != GSS_C_NO_CONTEXT) 154 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER); 155 if ((*ctx)->name != GSS_C_NO_NAME) 156 gss_release_name(&ms, &(*ctx)->name); 157 if ((*ctx)->oid != GSS_C_NO_OID) { 158 xfree((*ctx)->oid->elements); 159 xfree((*ctx)->oid); 160 (*ctx)->oid = GSS_C_NO_OID; 161 } 162 if ((*ctx)->creds != GSS_C_NO_CREDENTIAL) 163 gss_release_cred(&ms, &(*ctx)->creds); 164 if ((*ctx)->client != GSS_C_NO_NAME) 165 gss_release_name(&ms, &(*ctx)->client); 166 if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL) 167 gss_release_cred(&ms, &(*ctx)->client_creds); 168 169 xfree(*ctx); 170 *ctx = NULL; 171 } 172 173 /* 174 * Wrapper to init_sec_context 175 * Requires that the context contains: 176 * oid 177 * server name (from ssh_gssapi_import_name) 178 */ 179 OM_uint32 180 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, 181 gss_buffer_desc* send_tok, OM_uint32 *flags) 182 { 183 int deleg_flag = 0; 184 185 if (deleg_creds) { 186 deleg_flag = GSS_C_DELEG_FLAG; 187 debug("Delegating credentials"); 188 } 189 190 ctx->major = gss_init_sec_context(&ctx->minor, 191 GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, 192 GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, 193 0, NULL, recv_tok, NULL, send_tok, flags, NULL); 194 195 if (GSS_ERROR(ctx->major)) 196 ssh_gssapi_error(ctx); 197 198 return (ctx->major); 199 } 200 201 /* Create a service name for the given host */ 202 OM_uint32 203 ssh_gssapi_import_name(Gssctxt *ctx, const char *host) 204 { 205 gss_buffer_desc gssbuf; 206 207 gssbuf.length = sizeof("host@") + strlen(host); 208 gssbuf.value = xmalloc(gssbuf.length); 209 snprintf(gssbuf.value, gssbuf.length, "host@%s", host); 210 211 if ((ctx->major = gss_import_name(&ctx->minor, 212 &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name))) 213 ssh_gssapi_error(ctx); 214 215 xfree(gssbuf.value); 216 return (ctx->major); 217 } 218 219 /* Acquire credentials for a server running on the current host. 220 * Requires that the context structure contains a valid OID 221 */ 222 223 /* Returns a GSSAPI error code */ 224 OM_uint32 225 ssh_gssapi_acquire_cred(Gssctxt *ctx) 226 { 227 OM_uint32 status; 228 char lname[MAXHOSTNAMELEN]; 229 gss_OID_set oidset; 230 231 gss_create_empty_oid_set(&status, &oidset); 232 gss_add_oid_set_member(&status, ctx->oid, &oidset); 233 234 if (gethostname(lname, MAXHOSTNAMELEN)) 235 return (-1); 236 237 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) 238 return (ctx->major); 239 240 if ((ctx->major = gss_acquire_cred(&ctx->minor, 241 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL))) 242 ssh_gssapi_error(ctx); 243 244 gss_release_oid_set(&status, &oidset); 245 return (ctx->major); 246 } 247 248 OM_uint32 249 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) 250 { 251 if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, 252 GSS_C_QOP_DEFAULT, buffer, hash))) 253 ssh_gssapi_error(ctx); 254 255 return (ctx->major); 256 } 257 258 void 259 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service, 260 const char *context) 261 { 262 buffer_init(b); 263 buffer_put_string(b, session_id2, session_id2_len); 264 buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST); 265 buffer_put_cstring(b, user); 266 buffer_put_cstring(b, service); 267 buffer_put_cstring(b, context); 268 } 269 270 OM_uint32 271 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) 272 { 273 if (*ctx) 274 ssh_gssapi_delete_ctx(ctx); 275 ssh_gssapi_build_ctx(ctx); 276 ssh_gssapi_set_oid(*ctx, oid); 277 return (ssh_gssapi_acquire_cred(*ctx)); 278 } 279 280 #endif /* GSSAPI */ 281