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curl/lib/vauth/krb5_sspi.c
Patrick Monnerat 19ea52da4d
vauth: factor base64 conversions out of authentication procedures 
Input challenges and returned messages are now in binary.
Conversions from/to base64 are performed by callers (currently curl_sasl.c
and http_ntlm.c).

Closes #6654
2021-04-22 09:06:07 +02:00

483 lines
16 KiB
C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2014 - 2021, Steve Holme, <steve_holme@hotmail.com>.
*
* 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 https://curl.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(USE_WINDOWS_SSPI) && defined(USE_KERBEROS5)
#include <curl/curl.h>
#include "vauth/vauth.h"
#include "urldata.h"
#include "warnless.h"
#include "curl_multibyte.h"
#include "sendf.h"
/* The last #include files should be: */
#include "curl_memory.h"
#include "memdebug.h"
/*
* Curl_auth_is_gssapi_supported()
*
* This is used to evaluate if GSSAPI (Kerberos V5) is supported.
*
* Parameters: None
*
* Returns TRUE if Kerberos V5 is supported by Windows SSPI.
*/
bool Curl_auth_is_gssapi_supported(void)
{
PSecPkgInfo SecurityPackage;
SECURITY_STATUS status;
/* Query the security package for Kerberos */
status = s_pSecFn->QuerySecurityPackageInfo((TCHAR *)
TEXT(SP_NAME_KERBEROS),
&SecurityPackage);
/* Release the package buffer as it is not required anymore */
if(status == SEC_E_OK) {
s_pSecFn->FreeContextBuffer(SecurityPackage);
}
return (status == SEC_E_OK ? TRUE : FALSE);
}
/*
* Curl_auth_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 in the format User or Domain\User.
* passwdp [in] - The user's password.
* service [in] - The service type such as http, smtp, pop or imap.
* host [in] - The host name.
* mutual_auth [in] - Flag specifying whether or not mutual authentication
* is enabled.
* chlg [in] - Optional challenge message.
* krb5 [in/out] - The Kerberos 5 data struct being used and modified.
* out [out] - The result storage.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data,
const char *userp,
const char *passwdp,
const char *service,
const char *host,
const bool mutual_auth,
const struct bufref *chlg,
struct kerberos5data *krb5,
struct bufref *out)
{
CURLcode result = CURLE_OK;
CtxtHandle context;
PSecPkgInfo SecurityPackage;
SecBuffer chlg_buf;
SecBuffer resp_buf;
SecBufferDesc chlg_desc;
SecBufferDesc resp_desc;
SECURITY_STATUS status;
unsigned long attrs;
TimeStamp expiry; /* For Windows 9x compatibility of SSPI calls */
if(!krb5->spn) {
/* Generate our SPN */
krb5->spn = Curl_auth_build_spn(service, host, NULL);
if(!krb5->spn)
return CURLE_OUT_OF_MEMORY;
}
if(!krb5->output_token) {
/* Query the security package for Kerberos */
status = s_pSecFn->QuerySecurityPackageInfo((TCHAR *)
TEXT(SP_NAME_KERBEROS),
&SecurityPackage);
if(status != SEC_E_OK) {
failf(data, "SSPI: couldn't get auth info");
return CURLE_AUTH_ERROR;
}
krb5->token_max = SecurityPackage->cbMaxToken;
/* Release the package buffer as it is not required anymore */
s_pSecFn->FreeContextBuffer(SecurityPackage);
/* Allocate our response buffer */
krb5->output_token = malloc(krb5->token_max);
if(!krb5->output_token)
return CURLE_OUT_OF_MEMORY;
}
if(!krb5->credentials) {
/* Do we have credentials to use or are we using single sign-on? */
if(userp && *userp) {
/* Populate our identity structure */
result = Curl_create_sspi_identity(userp, passwdp, &krb5->identity);
if(result)
return result;
/* Allow proper cleanup of the identity structure */
krb5->p_identity = &krb5->identity;
}
else
/* Use the current Windows user */
krb5->p_identity = NULL;
/* Allocate our credentials handle */
krb5->credentials = calloc(1, sizeof(CredHandle));
if(!krb5->credentials)
return CURLE_OUT_OF_MEMORY;
/* Acquire our credentials handle */
status = s_pSecFn->AcquireCredentialsHandle(NULL,
(TCHAR *)
TEXT(SP_NAME_KERBEROS),
SECPKG_CRED_OUTBOUND, NULL,
krb5->p_identity, NULL, NULL,
krb5->credentials, &expiry);
if(status != SEC_E_OK)
return CURLE_LOGIN_DENIED;
/* Allocate our new context handle */
krb5->context = calloc(1, sizeof(CtxtHandle));
if(!krb5->context)
return CURLE_OUT_OF_MEMORY;
}
if(chlg) {
if(!Curl_bufref_len(chlg)) {
infof(data, "GSSAPI handshake failure (empty challenge message)\n");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Setup the challenge "input" security buffer */
chlg_desc.ulVersion = SECBUFFER_VERSION;
chlg_desc.cBuffers = 1;
chlg_desc.pBuffers = &chlg_buf;
chlg_buf.BufferType = SECBUFFER_TOKEN;
chlg_buf.pvBuffer = (void *) Curl_bufref_ptr(chlg);
chlg_buf.cbBuffer = curlx_uztoul(Curl_bufref_len(chlg));
}
/* Setup the response "output" security buffer */
resp_desc.ulVersion = SECBUFFER_VERSION;
resp_desc.cBuffers = 1;
resp_desc.pBuffers = &resp_buf;
resp_buf.BufferType = SECBUFFER_TOKEN;
resp_buf.pvBuffer = krb5->output_token;
resp_buf.cbBuffer = curlx_uztoul(krb5->token_max);
/* Generate our challenge-response message */
status = s_pSecFn->InitializeSecurityContext(krb5->credentials,
chlg ? krb5->context : NULL,
krb5->spn,
(mutual_auth ?
ISC_REQ_MUTUAL_AUTH : 0),
0, SECURITY_NATIVE_DREP,
chlg ? &chlg_desc : NULL, 0,
&context,
&resp_desc, &attrs,
&expiry);
if(status == SEC_E_INSUFFICIENT_MEMORY)
return CURLE_OUT_OF_MEMORY;
if(status != SEC_E_OK && status != SEC_I_CONTINUE_NEEDED)
return CURLE_AUTH_ERROR;
if(memcmp(&context, krb5->context, sizeof(context))) {
s_pSecFn->DeleteSecurityContext(krb5->context);
memcpy(krb5->context, &context, sizeof(context));
}
if(resp_buf.cbBuffer) {
result = Curl_bufref_memdup(out, resp_buf.pvBuffer, resp_buf.cbBuffer);
}
else if(mutual_auth)
Curl_bufref_set(out, "", 0, NULL);
else
Curl_bufref_set(out, NULL, 0, NULL);
return result;
}
/*
* Curl_auth_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.
* chlg [in] - The optional challenge message.
* krb5 [in/out] - The Kerberos 5 data struct being used and modified.
* out [out] - The result storage.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_auth_create_gssapi_security_message(struct Curl_easy *data,
const struct bufref *chlg,
struct kerberos5data *krb5,
struct bufref *out)
{
size_t offset = 0;
size_t messagelen = 0;
size_t appdatalen = 0;
unsigned char *trailer = NULL;
unsigned char *message = NULL;
unsigned char *padding = NULL;
unsigned char *appdata = NULL;
SecBuffer input_buf[2];
SecBuffer wrap_buf[3];
SecBufferDesc input_desc;
SecBufferDesc wrap_desc;
unsigned long indata = 0;
unsigned long outdata = 0;
unsigned long qop = 0;
unsigned long sec_layer = 0;
unsigned long max_size = 0;
SecPkgContext_Sizes sizes;
SecPkgCredentials_Names names;
SECURITY_STATUS status;
char *user_name;
/* Ensure we have a valid challenge message */
if(!Curl_bufref_len(chlg)) {
infof(data, "GSSAPI handshake failure (empty security message)\n");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Get our response size information */
status = s_pSecFn->QueryContextAttributes(krb5->context,
SECPKG_ATTR_SIZES,
&sizes);
if(status == SEC_E_INSUFFICIENT_MEMORY)
return CURLE_OUT_OF_MEMORY;
if(status != SEC_E_OK)
return CURLE_AUTH_ERROR;
/* Get the fully qualified username back from the context */
status = s_pSecFn->QueryCredentialsAttributes(krb5->credentials,
SECPKG_CRED_ATTR_NAMES,
&names);
if(status == SEC_E_INSUFFICIENT_MEMORY)
return CURLE_OUT_OF_MEMORY;
if(status != SEC_E_OK)
return CURLE_AUTH_ERROR;
/* Setup the "input" security buffer */
input_desc.ulVersion = SECBUFFER_VERSION;
input_desc.cBuffers = 2;
input_desc.pBuffers = input_buf;
input_buf[0].BufferType = SECBUFFER_STREAM;
input_buf[0].pvBuffer = (void *) Curl_bufref_ptr(chlg);
input_buf[0].cbBuffer = curlx_uztoul(Curl_bufref_len(chlg));
input_buf[1].BufferType = SECBUFFER_DATA;
input_buf[1].pvBuffer = NULL;
input_buf[1].cbBuffer = 0;
/* Decrypt the inbound challenge and obtain the qop */
status = s_pSecFn->DecryptMessage(krb5->context, &input_desc, 0, &qop);
if(status != SEC_E_OK) {
infof(data, "GSSAPI handshake failure (empty security message)\n");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Not 4 octets long so fail as per RFC4752 Section 3.1 */
if(input_buf[1].cbBuffer != 4) {
infof(data, "GSSAPI handshake failure (invalid security data)\n");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Copy the data out and free the challenge as it is not required anymore */
memcpy(&indata, input_buf[1].pvBuffer, 4);
s_pSecFn->FreeContextBuffer(input_buf[1].pvBuffer);
/* Extract the security layer */
sec_layer = indata & 0x000000FF;
if(!(sec_layer & KERB_WRAP_NO_ENCRYPT)) {
infof(data, "GSSAPI handshake failure (invalid security layer)\n");
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 the trailer */
trailer = malloc(sizes.cbSecurityTrailer);
if(!trailer)
return CURLE_OUT_OF_MEMORY;
/* Convert the user name to UTF8 when operating with Unicode */
user_name = curlx_convert_tchar_to_UTF8(names.sUserName);
if(!user_name) {
free(trailer);
return CURLE_OUT_OF_MEMORY;
}
/* Allocate our message */
messagelen = sizeof(outdata) + strlen(user_name) + 1;
message = malloc(messagelen);
if(!message) {
free(trailer);
curlx_unicodefree(user_name);
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: Despite 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));
strcpy((char *) message + sizeof(outdata), user_name);
curlx_unicodefree(user_name);
/* Allocate the padding */
padding = malloc(sizes.cbBlockSize);
if(!padding) {
free(message);
free(trailer);
return CURLE_OUT_OF_MEMORY;
}
/* Setup the "authentication data" security buffer */
wrap_desc.ulVersion = SECBUFFER_VERSION;
wrap_desc.cBuffers = 3;
wrap_desc.pBuffers = wrap_buf;
wrap_buf[0].BufferType = SECBUFFER_TOKEN;
wrap_buf[0].pvBuffer = trailer;
wrap_buf[0].cbBuffer = sizes.cbSecurityTrailer;
wrap_buf[1].BufferType = SECBUFFER_DATA;
wrap_buf[1].pvBuffer = message;
wrap_buf[1].cbBuffer = curlx_uztoul(messagelen);
wrap_buf[2].BufferType = SECBUFFER_PADDING;
wrap_buf[2].pvBuffer = padding;
wrap_buf[2].cbBuffer = sizes.cbBlockSize;
/* Encrypt the data */
status = s_pSecFn->EncryptMessage(krb5->context, KERB_WRAP_NO_ENCRYPT,
&wrap_desc, 0);
if(status != SEC_E_OK) {
free(padding);
free(message);
free(trailer);
if(status == SEC_E_INSUFFICIENT_MEMORY)
return CURLE_OUT_OF_MEMORY;
return CURLE_AUTH_ERROR;
}
/* Allocate the encryption (wrap) buffer */
appdatalen = wrap_buf[0].cbBuffer + wrap_buf[1].cbBuffer +
wrap_buf[2].cbBuffer;
appdata = malloc(appdatalen);
if(!appdata) {
free(padding);
free(message);
free(trailer);
return CURLE_OUT_OF_MEMORY;
}
/* Populate the encryption buffer */
memcpy(appdata, wrap_buf[0].pvBuffer, wrap_buf[0].cbBuffer);
offset += wrap_buf[0].cbBuffer;
memcpy(appdata + offset, wrap_buf[1].pvBuffer, wrap_buf[1].cbBuffer);
offset += wrap_buf[1].cbBuffer;
memcpy(appdata + offset, wrap_buf[2].pvBuffer, wrap_buf[2].cbBuffer);
/* Free all of our local buffers */
free(padding);
free(message);
free(trailer);
/* Return the response. */
Curl_bufref_set(out, appdata, appdatalen, curl_free);
return CURLE_OK;
}
/*
* Curl_auth_cleanup_gssapi()
*
* This is used to clean up the GSSAPI (Kerberos V5) specific data.
*
* Parameters:
*
* krb5 [in/out] - The Kerberos 5 data struct being cleaned up.
*
*/
void Curl_auth_cleanup_gssapi(struct kerberos5data *krb5)
{
/* Free our security context */
if(krb5->context) {
s_pSecFn->DeleteSecurityContext(krb5->context);
free(krb5->context);
krb5->context = NULL;
}
/* Free our credentials handle */
if(krb5->credentials) {
s_pSecFn->FreeCredentialsHandle(krb5->credentials);
free(krb5->credentials);
krb5->credentials = NULL;
}
/* Free our identity */
Curl_sspi_free_identity(krb5->p_identity);
krb5->p_identity = NULL;
/* Free the SPN and output token */
Curl_safefree(krb5->spn);
Curl_safefree(krb5->output_token);
/* Reset any variables */
krb5->token_max = 0;
}
#endif /* USE_WINDOWS_SSPI && USE_KERBEROS5*/
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