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curl/lib/curl_sasl_gssapi.c
Dan Fandrich 35648f2e79 curl_memory: make curl_memory.h the second-last header file loaded 
This header file must be included after all header files except
memdebug.h, as it does similar memory function redefinitions and can be
similarly affected by conflicting definitions in system or dependent
library headers.
2015-03-24 23:47:01 +01:00

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