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393 lines
13 KiB
393 lines
13 KiB
/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) 2014 - 2015, Steve Holme, <steve_holme@hotmail.com>.
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* Copyright (C) 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at http://curl.haxx.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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* RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
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*
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***************************************************************************/
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#include "curl_setup.h"
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#if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5)
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#include <curl/curl.h>
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#include "curl_sasl.h"
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#include "urldata.h"
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#include "curl_base64.h"
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#include "curl_gssapi.h"
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#include "sendf.h"
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#include "curl_printf.h"
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/* The last #include files should be: */
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#include "curl_memory.h"
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#include "memdebug.h"
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/*
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* Curl_sasl_build_gssapi_spn()
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*
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* This is used to build a SPN string in the format service@host.
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*
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* Parameters:
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*
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* serivce [in] - The service type such as www, smtp, pop or imap.
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* host [in] - The host name or realm.
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*
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* Returns a pointer to the newly allocated SPN.
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*/
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char *Curl_sasl_build_gssapi_spn(const char *service, const char *host)
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{
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/* Generate and return our SPN */
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return aprintf("%s@%s", service, host);
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}
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/*
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* Curl_sasl_create_gssapi_user_message()
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*
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* This is used to generate an already encoded GSSAPI (Kerberos V5) user token
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* message ready for sending to the recipient.
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*
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* Parameters:
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*
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* data [in] - The session handle.
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* userp [in] - The user name.
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* passdwp [in] - The user's password.
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* service [in] - The service type such as www, smtp, pop or imap.
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* mutual_auth [in] - Flag specifying whether or not mutual authentication
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* is enabled.
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* chlg64 [in] - Pointer to the optional base64 encoded challenge
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* message.
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* krb5 [in/out] - The gssapi data struct being used and modified.
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* outptr [in/out] - The address where a pointer to newly allocated memory
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* holding the result will be stored upon completion.
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* outlen [out] - The length of the output message.
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*
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* Returns CURLE_OK on success.
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*/
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CURLcode Curl_sasl_create_gssapi_user_message(struct SessionHandle *data,
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const char *userp,
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const char *passwdp,
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const char *service,
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const bool mutual_auth,
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const char *chlg64,
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struct kerberos5data *krb5,
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char **outptr, size_t *outlen)
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{
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CURLcode result = CURLE_OK;
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size_t chlglen = 0;
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unsigned char *chlg = NULL;
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OM_uint32 gss_status;
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OM_uint32 gss_major_status;
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OM_uint32 gss_minor_status;
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gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
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(void) userp;
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(void) passwdp;
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if(krb5->context == GSS_C_NO_CONTEXT) {
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/* Generate our SPN */
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char *spn = Curl_sasl_build_gssapi_spn(service,
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data->easy_conn->host.name);
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if(!spn)
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return CURLE_OUT_OF_MEMORY;
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/* Populate the SPN structure */
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spn_token.value = spn;
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spn_token.length = strlen(spn);
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/* Import the SPN */
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gss_major_status = gss_import_name(&gss_minor_status, &spn_token,
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GSS_C_NT_HOSTBASED_SERVICE, &krb5->spn);
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if(GSS_ERROR(gss_major_status)) {
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Curl_gss_log_error(data, gss_minor_status, "gss_import_name() failed: ");
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free(spn);
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return CURLE_OUT_OF_MEMORY;
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}
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free(spn);
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}
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else {
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/* Decode the base-64 encoded challenge message */
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if(strlen(chlg64) && *chlg64 != '=') {
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result = Curl_base64_decode(chlg64, &chlg, &chlglen);
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if(result)
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return result;
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}
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/* Ensure we have a valid challenge message */
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if(!chlg) {
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infof(data, "GSSAPI handshake failure (empty challenge message)\n");
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return CURLE_BAD_CONTENT_ENCODING;
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}
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/* Setup the challenge "input" security buffer */
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input_token.value = chlg;
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input_token.length = chlglen;
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}
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gss_major_status = Curl_gss_init_sec_context(data,
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&gss_minor_status,
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&krb5->context,
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krb5->spn,
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&Curl_krb5_mech_oid,
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GSS_C_NO_CHANNEL_BINDINGS,
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&input_token,
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&output_token,
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mutual_auth,
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NULL);
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free(input_token.value);
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if(GSS_ERROR(gss_major_status)) {
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if(output_token.value)
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gss_release_buffer(&gss_status, &output_token);
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Curl_gss_log_error(data, gss_minor_status,
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"gss_init_sec_context() failed: ");
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return CURLE_RECV_ERROR;
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}
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if(output_token.value && output_token.length) {
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/* Base64 encode the response */
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result = Curl_base64_encode(data, (char *) output_token.value,
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output_token.length, outptr, outlen);
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gss_release_buffer(&gss_status, &output_token);
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}
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return result;
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}
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/*
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* Curl_sasl_create_gssapi_security_message()
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*
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* This is used to generate an already encoded GSSAPI (Kerberos V5) security
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* token message ready for sending to the recipient.
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*
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* Parameters:
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*
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* data [in] - The session handle.
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* chlg64 [in] - Pointer to the optional base64 encoded challenge message.
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* krb5 [in/out] - The gssapi data struct being used and modified.
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* outptr [in/out] - The address where a pointer to newly allocated memory
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* holding the result will be stored upon completion.
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* outlen [out] - The length of the output message.
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*
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* Returns CURLE_OK on success.
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*/
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CURLcode Curl_sasl_create_gssapi_security_message(struct SessionHandle *data,
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const char *chlg64,
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struct kerberos5data *krb5,
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char **outptr,
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size_t *outlen)
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{
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CURLcode result = CURLE_OK;
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size_t chlglen = 0;
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size_t messagelen = 0;
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unsigned char *chlg = NULL;
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unsigned char *message = NULL;
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OM_uint32 gss_status;
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OM_uint32 gss_major_status;
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OM_uint32 gss_minor_status;
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gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
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unsigned int indata = 0;
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unsigned int outdata = 0;
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gss_qop_t qop = GSS_C_QOP_DEFAULT;
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unsigned int sec_layer = 0;
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unsigned int max_size = 0;
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gss_name_t username = GSS_C_NO_NAME;
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gss_buffer_desc username_token;
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/* Decode the base-64 encoded input message */
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if(strlen(chlg64) && *chlg64 != '=') {
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result = Curl_base64_decode(chlg64, &chlg, &chlglen);
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if(result)
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return result;
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}
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/* Ensure we have a valid challenge message */
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if(!chlg) {
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infof(data, "GSSAPI handshake failure (empty security message)\n");
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return CURLE_BAD_CONTENT_ENCODING;
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}
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/* Get the fully qualified username back from the context */
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gss_major_status = gss_inquire_context(&gss_minor_status, krb5->context,
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&username, NULL, NULL, NULL, NULL,
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NULL, NULL);
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if(GSS_ERROR(gss_major_status)) {
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Curl_gss_log_error(data, gss_minor_status,
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"gss_inquire_context() failed: ");
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free(chlg);
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return CURLE_OUT_OF_MEMORY;
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}
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/* Convert the username from internal format to a displayable token */
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gss_major_status = gss_display_name(&gss_minor_status, username,
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&username_token, NULL);
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if(GSS_ERROR(gss_major_status)) {
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Curl_gss_log_error(data, gss_minor_status, "gss_display_name() failed: ");
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free(chlg);
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return CURLE_OUT_OF_MEMORY;
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}
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/* Setup the challenge "input" security buffer */
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input_token.value = chlg;
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input_token.length = chlglen;
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/* Decrypt the inbound challenge and obtain the qop */
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gss_major_status = gss_unwrap(&gss_minor_status, krb5->context, &input_token,
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&output_token, NULL, &qop);
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if(GSS_ERROR(gss_major_status)) {
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Curl_gss_log_error(data, gss_minor_status, "gss_unwrap() failed: ");
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gss_release_buffer(&gss_status, &username_token);
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free(chlg);
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return CURLE_BAD_CONTENT_ENCODING;
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}
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/* Not 4 octets long so fail as per RFC4752 Section 3.1 */
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if(output_token.length != 4) {
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infof(data, "GSSAPI handshake failure (invalid security data)\n");
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gss_release_buffer(&gss_status, &username_token);
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free(chlg);
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return CURLE_BAD_CONTENT_ENCODING;
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}
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/* Copy the data out and free the challenge as it is not required anymore */
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memcpy(&indata, output_token.value, 4);
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gss_release_buffer(&gss_status, &output_token);
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free(chlg);
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/* Extract the security layer */
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sec_layer = indata & 0x000000FF;
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if(!(sec_layer & GSSAUTH_P_NONE)) {
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infof(data, "GSSAPI handshake failure (invalid security layer)\n");
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gss_release_buffer(&gss_status, &username_token);
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return CURLE_BAD_CONTENT_ENCODING;
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}
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/* Extract the maximum message size the server can receive */
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max_size = ntohl(indata & 0xFFFFFF00);
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if(max_size > 0) {
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/* The server has told us it supports a maximum receive buffer, however, as
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we don't require one unless we are encrypting data, we tell the server
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our receive buffer is zero. */
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max_size = 0;
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}
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/* Allocate our message */
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messagelen = sizeof(outdata) + username_token.length + 1;
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message = malloc(messagelen);
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if(!message) {
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gss_release_buffer(&gss_status, &username_token);
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return CURLE_OUT_OF_MEMORY;
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}
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/* Populate the message with the security layer, client supported receive
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message size and authorization identity including the 0x00 based
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terminator. Note: Dispite RFC4752 Section 3.1 stating "The authorization
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identity is not terminated with the zero-valued (%x00) octet." it seems
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necessary to include it. */
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outdata = htonl(max_size) | sec_layer;
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memcpy(message, &outdata, sizeof(outdata));
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memcpy(message + sizeof(outdata), username_token.value,
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username_token.length);
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message[messagelen - 1] = '\0';
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/* Free the username token as it is not required anymore */
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gss_release_buffer(&gss_status, &username_token);
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/* Setup the "authentication data" security buffer */
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input_token.value = message;
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input_token.length = messagelen;
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/* Encrypt the data */
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gss_major_status = gss_wrap(&gss_minor_status, krb5->context, 0,
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GSS_C_QOP_DEFAULT, &input_token, NULL,
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&output_token);
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if(GSS_ERROR(gss_major_status)) {
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Curl_gss_log_error(data, gss_minor_status, "gss_wrap() failed: ");
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free(message);
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return CURLE_OUT_OF_MEMORY;
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}
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/* Base64 encode the response */
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result = Curl_base64_encode(data, (char *) output_token.value,
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output_token.length, outptr, outlen);
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/* Free the output buffer */
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gss_release_buffer(&gss_status, &output_token);
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/* Free the message buffer */
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free(message);
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return result;
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}
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/*
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* Curl_sasl_gssapi_cleanup()
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*
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* This is used to clean up the gssapi specific data.
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*
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* Parameters:
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*
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* krb5 [in/out] - The kerberos 5 data struct being cleaned up.
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*
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*/
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void Curl_sasl_gssapi_cleanup(struct kerberos5data *krb5)
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{
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OM_uint32 minor_status;
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/* Free our security context */
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if(krb5->context != GSS_C_NO_CONTEXT) {
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gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER);
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krb5->context = GSS_C_NO_CONTEXT;
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}
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/* Free the SPN */
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if(krb5->spn != GSS_C_NO_NAME) {
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gss_release_name(&minor_status, &krb5->spn);
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krb5->spn = GSS_C_NO_NAME;
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}
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}
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#endif /* HAVE_GSSAPI && USE_KERBEROS5 */
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