1 /* $OpenBSD: gss-genr.c,v 1.23 2015/01/20 23:14:00 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 2001-2007 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 #ifdef GSSAPI 28 29 #include <sys/param.h> 30 31 #include <stdarg.h> 32 #include <string.h> 33 #include <limits.h> 34 35 #include "xmalloc.h" 36 #include "buffer.h" 37 #include "log.h" 38 #include "ssh2.h" 39 40 #include "ssh-gss.h" 41 42 extern u_char *session_id2; 43 extern u_int session_id2_len; 44 45 /* Check that the OID in a data stream matches that in the context */ 46 int 47 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) 48 { 49 return (ctx != NULL && ctx->oid != GSS_C_NO_OID && 50 ctx->oid->length == len && 51 memcmp(ctx->oid->elements, data, len) == 0); 52 } 53 54 /* Set the contexts OID from a data stream */ 55 void 56 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) 57 { 58 if (ctx->oid != GSS_C_NO_OID) { 59 free(ctx->oid->elements); 60 free(ctx->oid); 61 } 62 ctx->oid = xcalloc(1, sizeof(gss_OID_desc)); 63 ctx->oid->length = len; 64 ctx->oid->elements = xmalloc(len); 65 memcpy(ctx->oid->elements, data, len); 66 } 67 68 /* Set the contexts OID */ 69 void 70 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) 71 { 72 ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length); 73 } 74 75 /* All this effort to report an error ... */ 76 void 77 ssh_gssapi_error(Gssctxt *ctxt) 78 { 79 char *s; 80 81 s = ssh_gssapi_last_error(ctxt, NULL, NULL); 82 debug("%s", s); 83 free(s); 84 } 85 86 char * 87 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status, 88 OM_uint32 *minor_status) 89 { 90 OM_uint32 lmin; 91 gss_buffer_desc msg = GSS_C_EMPTY_BUFFER; 92 OM_uint32 ctx; 93 Buffer b; 94 char *ret; 95 96 buffer_init(&b); 97 98 if (major_status != NULL) 99 *major_status = ctxt->major; 100 if (minor_status != NULL) 101 *minor_status = ctxt->minor; 102 103 ctx = 0; 104 /* The GSSAPI error */ 105 do { 106 gss_display_status(&lmin, ctxt->major, 107 GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg); 108 109 buffer_append(&b, msg.value, msg.length); 110 buffer_put_char(&b, '\n'); 111 112 gss_release_buffer(&lmin, &msg); 113 } while (ctx != 0); 114 115 /* The mechanism specific error */ 116 do { 117 gss_display_status(&lmin, ctxt->minor, 118 GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg); 119 120 buffer_append(&b, msg.value, msg.length); 121 buffer_put_char(&b, '\n'); 122 123 gss_release_buffer(&lmin, &msg); 124 } while (ctx != 0); 125 126 buffer_put_char(&b, '\0'); 127 ret = xmalloc(buffer_len(&b)); 128 buffer_get(&b, ret, buffer_len(&b)); 129 buffer_free(&b); 130 return (ret); 131 } 132 133 /* 134 * Initialise our GSSAPI context. We use this opaque structure to contain all 135 * of the data which both the client and server need to persist across 136 * {accept,init}_sec_context calls, so that when we do it from the userauth 137 * stuff life is a little easier 138 */ 139 void 140 ssh_gssapi_build_ctx(Gssctxt **ctx) 141 { 142 *ctx = xcalloc(1, sizeof (Gssctxt)); 143 (*ctx)->context = GSS_C_NO_CONTEXT; 144 (*ctx)->name = GSS_C_NO_NAME; 145 (*ctx)->oid = GSS_C_NO_OID; 146 (*ctx)->creds = GSS_C_NO_CREDENTIAL; 147 (*ctx)->client = GSS_C_NO_NAME; 148 (*ctx)->client_creds = GSS_C_NO_CREDENTIAL; 149 } 150 151 /* Delete our context, providing it has been built correctly */ 152 void 153 ssh_gssapi_delete_ctx(Gssctxt **ctx) 154 { 155 OM_uint32 ms; 156 157 if ((*ctx) == NULL) 158 return; 159 if ((*ctx)->context != GSS_C_NO_CONTEXT) 160 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER); 161 if ((*ctx)->name != GSS_C_NO_NAME) 162 gss_release_name(&ms, &(*ctx)->name); 163 if ((*ctx)->oid != GSS_C_NO_OID) { 164 free((*ctx)->oid->elements); 165 free((*ctx)->oid); 166 (*ctx)->oid = GSS_C_NO_OID; 167 } 168 if ((*ctx)->creds != GSS_C_NO_CREDENTIAL) 169 gss_release_cred(&ms, &(*ctx)->creds); 170 if ((*ctx)->client != GSS_C_NO_NAME) 171 gss_release_name(&ms, &(*ctx)->client); 172 if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL) 173 gss_release_cred(&ms, &(*ctx)->client_creds); 174 175 free(*ctx); 176 *ctx = NULL; 177 } 178 179 /* 180 * Wrapper to init_sec_context 181 * Requires that the context contains: 182 * oid 183 * server name (from ssh_gssapi_import_name) 184 */ 185 OM_uint32 186 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, 187 gss_buffer_desc* send_tok, OM_uint32 *flags) 188 { 189 int deleg_flag = 0; 190 191 if (deleg_creds) { 192 deleg_flag = GSS_C_DELEG_FLAG; 193 debug("Delegating credentials"); 194 } 195 196 ctx->major = gss_init_sec_context(&ctx->minor, 197 GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, 198 GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, 199 0, NULL, recv_tok, NULL, send_tok, flags, NULL); 200 201 if (GSS_ERROR(ctx->major)) 202 ssh_gssapi_error(ctx); 203 204 return (ctx->major); 205 } 206 207 /* Create a service name for the given host */ 208 OM_uint32 209 ssh_gssapi_import_name(Gssctxt *ctx, const char *host) 210 { 211 gss_buffer_desc gssbuf; 212 char *val; 213 214 xasprintf(&val, "host@%s", host); 215 gssbuf.value = val; 216 gssbuf.length = strlen(gssbuf.value); 217 218 if ((ctx->major = gss_import_name(&ctx->minor, 219 &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name))) 220 ssh_gssapi_error(ctx); 221 222 free(gssbuf.value); 223 return (ctx->major); 224 } 225 226 OM_uint32 227 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) 228 { 229 if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, 230 GSS_C_QOP_DEFAULT, buffer, hash))) 231 ssh_gssapi_error(ctx); 232 233 return (ctx->major); 234 } 235 236 void 237 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service, 238 const char *context) 239 { 240 buffer_init(b); 241 buffer_put_string(b, session_id2, session_id2_len); 242 buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST); 243 buffer_put_cstring(b, user); 244 buffer_put_cstring(b, service); 245 buffer_put_cstring(b, context); 246 } 247 248 int 249 ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) 250 { 251 gss_buffer_desc token = GSS_C_EMPTY_BUFFER; 252 OM_uint32 major, minor; 253 gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"}; 254 255 /* RFC 4462 says we MUST NOT do SPNEGO */ 256 if (oid->length == spnego_oid.length && 257 (memcmp(oid->elements, spnego_oid.elements, oid->length) == 0)) 258 return 0; /* false */ 259 260 ssh_gssapi_build_ctx(ctx); 261 ssh_gssapi_set_oid(*ctx, oid); 262 major = ssh_gssapi_import_name(*ctx, host); 263 if (!GSS_ERROR(major)) { 264 major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, 265 NULL); 266 gss_release_buffer(&minor, &token); 267 if ((*ctx)->context != GSS_C_NO_CONTEXT) 268 gss_delete_sec_context(&minor, &(*ctx)->context, 269 GSS_C_NO_BUFFER); 270 } 271 272 if (GSS_ERROR(major)) 273 ssh_gssapi_delete_ctx(ctx); 274 275 return (!GSS_ERROR(major)); 276 } 277 278 #endif /* GSSAPI */ 279