curl/lib/vauth/krb5_gssapi.c
Daniel Stenberg 625f2c1644
lib: include files using known path
by including headers using "../[header]" when done from C files in
subdirectories, we do not need to specify the lib source dir as an
include path and we reduce the risk of header name collisions with
headers in the SDK using the same file names.

Idea-by: Kai Pastor

Ref: #16949
Closes #16991
2025-04-08 17:00:00 +02:00

334 lines
11 KiB
C

/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Steve Holme, <steve_holme@hotmail.com>.
* Copyright (C) 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 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.
*
* SPDX-License-Identifier: curl
*
* RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
*
***************************************************************************/
#include "../curl_setup.h"
#if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5)
#include <curl/curl.h>
#include "vauth.h"
#include "../curl_sasl.h"
#include "../urldata.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"
#if defined(__GNUC__) && defined(__APPLE__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#endif
/*
* 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 the GSS-API library.
*/
bool Curl_auth_is_gssapi_supported(void)
{
return TRUE;
}
/*
* 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 username.
* passwdp [in] - The user's password.
* service [in] - The service type such as http, smtp, pop or imap.
* host [in[ - The hostname.
* 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;
OM_uint32 major_status;
OM_uint32 minor_status;
OM_uint32 unused_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->spn) {
/* Generate our SPN */
char *spn = Curl_auth_build_spn(service, NULL, host);
if(!spn)
return CURLE_OUT_OF_MEMORY;
/* Populate the SPN structure */
spn_token.value = spn;
spn_token.length = strlen(spn);
/* Import the SPN */
major_status = gss_import_name(&minor_status, &spn_token,
GSS_C_NT_HOSTBASED_SERVICE, &krb5->spn);
if(GSS_ERROR(major_status)) {
Curl_gss_log_error(data, "gss_import_name() failed: ",
major_status, minor_status);
free(spn);
return CURLE_AUTH_ERROR;
}
free(spn);
}
if(chlg) {
if(!Curl_bufref_len(chlg)) {
infof(data, "GSSAPI handshake failure (empty challenge message)");
return CURLE_BAD_CONTENT_ENCODING;
}
input_token.value = CURL_UNCONST(Curl_bufref_ptr(chlg));
input_token.length = Curl_bufref_len(chlg);
}
major_status = Curl_gss_init_sec_context(data,
&minor_status,
&krb5->context,
krb5->spn,
&Curl_krb5_mech_oid,
GSS_C_NO_CHANNEL_BINDINGS,
&input_token,
&output_token,
mutual_auth,
NULL);
if(GSS_ERROR(major_status)) {
if(output_token.value)
gss_release_buffer(&unused_status, &output_token);
Curl_gss_log_error(data, "gss_init_sec_context() failed: ",
major_status, minor_status);
return CURLE_AUTH_ERROR;
}
if(output_token.value && output_token.length) {
result = Curl_bufref_memdup(out, output_token.value, output_token.length);
gss_release_buffer(&unused_status, &output_token);
}
else
Curl_bufref_set(out, mutual_auth ? "": 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.
* authzid [in] - The authorization identity if some.
* 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_security_message(struct Curl_easy *data,
const char *authzid,
const struct bufref *chlg,
struct kerberos5data *krb5,
struct bufref *out)
{
CURLcode result = CURLE_OK;
size_t messagelen = 0;
unsigned char *message = NULL;
OM_uint32 major_status;
OM_uint32 minor_status;
OM_uint32 unused_status;
gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
unsigned char *indata;
gss_qop_t qop = GSS_C_QOP_DEFAULT;
unsigned int sec_layer = 0;
unsigned int max_size = 0;
/* Ensure we have a valid challenge message */
if(!Curl_bufref_len(chlg)) {
infof(data, "GSSAPI handshake failure (empty security message)");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Setup the challenge "input" security buffer */
input_token.value = CURL_UNCONST(Curl_bufref_ptr(chlg));
input_token.length = Curl_bufref_len(chlg);
/* Decrypt the inbound challenge and obtain the qop */
major_status = gss_unwrap(&minor_status, krb5->context, &input_token,
&output_token, NULL, &qop);
if(GSS_ERROR(major_status)) {
Curl_gss_log_error(data, "gss_unwrap() failed: ",
major_status, minor_status);
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)");
return CURLE_BAD_CONTENT_ENCODING;
}
/* Extract the security layer and the maximum message size */
indata = output_token.value;
sec_layer = indata[0];
max_size = ((unsigned int)indata[1] << 16) |
((unsigned int)indata[2] << 8) | indata[3];
/* Free the challenge as it is not required anymore */
gss_release_buffer(&unused_status, &output_token);
/* Process the security layer */
if(!(sec_layer & GSSAUTH_P_NONE)) {
infof(data, "GSSAPI handshake failure (invalid security layer)");
return CURLE_BAD_CONTENT_ENCODING;
}
sec_layer &= GSSAUTH_P_NONE; /* We do not support a security layer */
/* Process the maximum message size the server can receive */
if(max_size > 0) {
/* The server has told us it supports a maximum receive buffer, however, as
we do not require one unless we are encrypting data, we tell the server
our receive buffer is zero. */
max_size = 0;
}
/* Allocate our message */
messagelen = 4;
if(authzid)
messagelen += strlen(authzid);
message = malloc(messagelen);
if(!message)
return CURLE_OUT_OF_MEMORY;
/* Populate the message with the security layer and client supported receive
message size. */
message[0] = sec_layer & 0xFF;
message[1] = (max_size >> 16) & 0xFF;
message[2] = (max_size >> 8) & 0xFF;
message[3] = max_size & 0xFF;
/* If given, append the authorization identity. */
if(authzid && *authzid)
memcpy(message + 4, authzid, messagelen - 4);
/* Setup the "authentication data" security buffer */
input_token.value = message;
input_token.length = messagelen;
/* Encrypt the data */
major_status = gss_wrap(&minor_status, krb5->context, 0,
GSS_C_QOP_DEFAULT, &input_token, NULL,
&output_token);
if(GSS_ERROR(major_status)) {
Curl_gss_log_error(data, "gss_wrap() failed: ",
major_status, minor_status);
free(message);
return CURLE_AUTH_ERROR;
}
/* Return the response. */
result = Curl_bufref_memdup(out, output_token.value, output_token.length);
/* Free the output buffer */
gss_release_buffer(&unused_status, &output_token);
/* Free the message buffer */
free(message);
return result;
}
/*
* 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)
{
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;
}
}
#if defined(__GNUC__) && defined(__APPLE__)
#pragma GCC diagnostic pop
#endif
#endif /* HAVE_GSSAPI && USE_KERBEROS5 */