1 /* $OpenBSD: gss-genr.c,v 1.4 2005/07/17 07:17:55 djm 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 "compat.h" 34 #include "log.h" 35 #include "monitor_wrap.h" 36 #include "ssh2.h" 37 38 #include "ssh-gss.h" 39 40 extern u_char *session_id2; 41 extern u_int session_id2_len; 42 43 /* Check that the OID in a data stream matches that in the context */ 44 int 45 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) 46 { 47 return (ctx != NULL && ctx->oid != GSS_C_NO_OID && 48 ctx->oid->length == len && 49 memcmp(ctx->oid->elements, data, len) == 0); 50 } 51 52 /* Set the contexts OID from a data stream */ 53 void 54 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) 55 { 56 if (ctx->oid != GSS_C_NO_OID) { 57 xfree(ctx->oid->elements); 58 xfree(ctx->oid); 59 } 60 ctx->oid = xmalloc(sizeof(gss_OID_desc)); 61 ctx->oid->length = len; 62 ctx->oid->elements = xmalloc(len); 63 memcpy(ctx->oid->elements, data, len); 64 } 65 66 /* Set the contexts OID */ 67 void 68 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) 69 { 70 ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length); 71 } 72 73 /* All this effort to report an error ... */ 74 void 75 ssh_gssapi_error(Gssctxt *ctxt) 76 { 77 debug("%s", ssh_gssapi_last_error(ctxt, NULL, NULL)); 78 } 79 80 char * 81 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status, 82 OM_uint32 *minor_status) 83 { 84 OM_uint32 lmin; 85 gss_buffer_desc msg = GSS_C_EMPTY_BUFFER; 86 OM_uint32 ctx; 87 Buffer b; 88 char *ret; 89 90 buffer_init(&b); 91 92 if (major_status != NULL) 93 *major_status = ctxt->major; 94 if (minor_status != NULL) 95 *minor_status = ctxt->minor; 96 97 ctx = 0; 98 /* The GSSAPI error */ 99 do { 100 gss_display_status(&lmin, ctxt->major, 101 GSS_C_GSS_CODE, GSS_C_NULL_OID, &ctx, &msg); 102 103 buffer_append(&b, msg.value, msg.length); 104 buffer_put_char(&b, '\n'); 105 106 gss_release_buffer(&lmin, &msg); 107 } while (ctx != 0); 108 109 /* The mechanism specific error */ 110 do { 111 gss_display_status(&lmin, ctxt->minor, 112 GSS_C_MECH_CODE, GSS_C_NULL_OID, &ctx, &msg); 113 114 buffer_append(&b, msg.value, msg.length); 115 buffer_put_char(&b, '\n'); 116 117 gss_release_buffer(&lmin, &msg); 118 } while (ctx != 0); 119 120 buffer_put_char(&b, '\0'); 121 ret = xmalloc(buffer_len(&b)); 122 buffer_get(&b, ret, buffer_len(&b)); 123 buffer_free(&b); 124 return (ret); 125 } 126 127 /* 128 * Initialise our GSSAPI context. We use this opaque structure to contain all 129 * of the data which both the client and server need to persist across 130 * {accept,init}_sec_context calls, so that when we do it from the userauth 131 * stuff life is a little easier 132 */ 133 void 134 ssh_gssapi_build_ctx(Gssctxt **ctx) 135 { 136 *ctx = xmalloc(sizeof (Gssctxt)); 137 (*ctx)->major = 0; 138 (*ctx)->minor = 0; 139 (*ctx)->context = GSS_C_NO_CONTEXT; 140 (*ctx)->name = GSS_C_NO_NAME; 141 (*ctx)->oid = GSS_C_NO_OID; 142 (*ctx)->creds = GSS_C_NO_CREDENTIAL; 143 (*ctx)->client = GSS_C_NO_NAME; 144 (*ctx)->client_creds = GSS_C_NO_CREDENTIAL; 145 } 146 147 /* Delete our context, providing it has been built correctly */ 148 void 149 ssh_gssapi_delete_ctx(Gssctxt **ctx) 150 { 151 OM_uint32 ms; 152 153 if ((*ctx) == NULL) 154 return; 155 if ((*ctx)->context != GSS_C_NO_CONTEXT) 156 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER); 157 if ((*ctx)->name != GSS_C_NO_NAME) 158 gss_release_name(&ms, &(*ctx)->name); 159 if ((*ctx)->oid != GSS_C_NO_OID) { 160 xfree((*ctx)->oid->elements); 161 xfree((*ctx)->oid); 162 (*ctx)->oid = GSS_C_NO_OID; 163 } 164 if ((*ctx)->creds != GSS_C_NO_CREDENTIAL) 165 gss_release_cred(&ms, &(*ctx)->creds); 166 if ((*ctx)->client != GSS_C_NO_NAME) 167 gss_release_name(&ms, &(*ctx)->client); 168 if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL) 169 gss_release_cred(&ms, &(*ctx)->client_creds); 170 171 xfree(*ctx); 172 *ctx = NULL; 173 } 174 175 /* 176 * Wrapper to init_sec_context 177 * Requires that the context contains: 178 * oid 179 * server name (from ssh_gssapi_import_name) 180 */ 181 OM_uint32 182 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, 183 gss_buffer_desc* send_tok, OM_uint32 *flags) 184 { 185 int deleg_flag = 0; 186 187 if (deleg_creds) { 188 deleg_flag = GSS_C_DELEG_FLAG; 189 debug("Delegating credentials"); 190 } 191 192 ctx->major = gss_init_sec_context(&ctx->minor, 193 GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, 194 GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, 195 0, NULL, recv_tok, NULL, send_tok, flags, NULL); 196 197 if (GSS_ERROR(ctx->major)) 198 ssh_gssapi_error(ctx); 199 200 return (ctx->major); 201 } 202 203 /* Create a service name for the given host */ 204 OM_uint32 205 ssh_gssapi_import_name(Gssctxt *ctx, const char *host) 206 { 207 gss_buffer_desc gssbuf; 208 209 gssbuf.length = sizeof("host@") + strlen(host); 210 gssbuf.value = xmalloc(gssbuf.length); 211 snprintf(gssbuf.value, gssbuf.length, "host@%s", host); 212 213 if ((ctx->major = gss_import_name(&ctx->minor, 214 &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name))) 215 ssh_gssapi_error(ctx); 216 217 xfree(gssbuf.value); 218 return (ctx->major); 219 } 220 221 /* Acquire credentials for a server running on the current host. 222 * Requires that the context structure contains a valid OID 223 */ 224 225 /* Returns a GSSAPI error code */ 226 OM_uint32 227 ssh_gssapi_acquire_cred(Gssctxt *ctx) 228 { 229 OM_uint32 status; 230 char lname[MAXHOSTNAMELEN]; 231 gss_OID_set oidset; 232 233 gss_create_empty_oid_set(&status, &oidset); 234 gss_add_oid_set_member(&status, ctx->oid, &oidset); 235 236 if (gethostname(lname, MAXHOSTNAMELEN)) 237 return (-1); 238 239 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) 240 return (ctx->major); 241 242 if ((ctx->major = gss_acquire_cred(&ctx->minor, 243 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL))) 244 ssh_gssapi_error(ctx); 245 246 gss_release_oid_set(&status, &oidset); 247 return (ctx->major); 248 } 249 250 OM_uint32 251 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) 252 { 253 if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, 254 GSS_C_QOP_DEFAULT, buffer, hash))) 255 ssh_gssapi_error(ctx); 256 257 return (ctx->major); 258 } 259 260 void 261 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service, 262 const char *context) 263 { 264 buffer_init(b); 265 buffer_put_string(b, session_id2, session_id2_len); 266 buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST); 267 buffer_put_cstring(b, user); 268 buffer_put_cstring(b, service); 269 buffer_put_cstring(b, context); 270 } 271 272 OM_uint32 273 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) { 274 if (*ctx) 275 ssh_gssapi_delete_ctx(ctx); 276 ssh_gssapi_build_ctx(ctx); 277 ssh_gssapi_set_oid(*ctx, oid); 278 return (ssh_gssapi_acquire_cred(*ctx)); 279 } 280 281 #endif /* GSSAPI */ 282