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/*
* SPDX-FileCopyrightText: 2014 Daniel Vrátil <dvratil@redhat.com>
* (c) 2016 - 2018 Daniel Vrátil <dvratil@kde.org>
*
* SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
*/
/**
* This is a very simple and single-purpose implementation of XOAUTH2 protocol
* for SASL used by KDE's KIMAP and IMAP resource in order to support OAuth
* Gmail authentication.
*
* This plugin does not even have a server-side part, and the client-side makes
* assumptions about it's use related to how KIMAP's LoginJob is implemented,
* so it's unsuitable for general-purpose use.
*
* The plugin is called libkdexoauth2.so to avoid conflict in case anyone ever
* writes a proper XOAUTH2 plugin for SASL.
*/
#include <config.h>
#include <stdio.h>
#include <string.h>
#include <sasl/sasl.h>
#include <sasl/saslplug.h>
#include <sasl/saslutil.h>
#include "plugin_common.h"
typedef struct client_context {
char *out_buf;
unsigned out_buf_len;
} client_context_t;
static int xoauth2_client_mech_new(void *glob_context, sasl_client_params_t *params, void **conn_context)
{
client_context_t *context;
/* Q_UNUSED */
(void)glob_context;
/* holds state are in */
context = params->utils->malloc(sizeof(client_context_t));
if (context == NULL) {
MEMERROR(params->utils);
return SASL_NOMEM;
}
memset(context, 0, sizeof(client_context_t));
*conn_context = context;
return SASL_OK;
}
static int xoauth2_client_mech_step(void *conn_context,
sasl_client_params_t *params,
const char *serverin,
unsigned serverinlen,
sasl_interact_t **prompt_need,
const char **clientout,
unsigned *clientoutlen,
sasl_out_params_t *oparams)
{
client_context_t *context = (client_context_t *)conn_context;
const sasl_utils_t *utils = params->utils;
const char *authid = NULL;
const char *token = NULL;
int auth_result = SASL_OK;
int token_result = SASL_OK;
int result;
*clientout = NULL;
*clientoutlen = 0;
/* Q_UNUSED */
(void)serverin;
(void)serverinlen;
if (params->props.min_ssf > params->external_ssf) {
SETERROR(params->utils, "SSF requested of XOAUTH2 plugin");
return SASL_TOOWEAK;
}
/* try to get the authid */
if (oparams->authid == NULL) {
fprintf(stderr, "[SASL-XOAUTH2] - Requesting authID!\n");
auth_result = _plug_get_authid(utils, &authid, prompt_need);
if ((auth_result != SASL_OK) && (auth_result != SASL_INTERACT)) {
fprintf(stderr, "[SASL-XOAUTH2] - _plug_get_authid FAILED!\n");
return auth_result;
}
}
/* try to get oauth token */
if (token == NULL) {
fprintf(stderr, "[SASL-XOAUTH2] - Requesting token!\n");
/* We don't use _plug_get_password because we don't really care much about
safety of the OAuth token */
token_result = _plug_get_simple(utils, SASL_CB_PASS, 1, &token, prompt_need);
if ((token_result != SASL_OK) && (token_result != SASL_INTERACT)) {
fprintf(stderr, "[SASL-XOAUTH2] - _plug_get_simple FAILED!\n");
return token_result;
}
}
/* free prompts we got */
if (prompt_need && *prompt_need) {
utils->free(*prompt_need);
*prompt_need = NULL;
}
/* if there are prompts not filled in */
if ((auth_result == SASL_INTERACT) || (token_result == SASL_INTERACT)) {
/* make the prompt list */
fprintf(stderr, "[SASL-XOAUTH2] - filling prompts!\n");
result = _plug_make_prompts(utils,
prompt_need,
NULL,
NULL,
auth_result == SASL_INTERACT ? "Please enter your authentication name" : NULL,
NULL,
token_result == SASL_INTERACT ? "Please enter OAuth token" : NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
NULL);
if (result != SASL_OK) {
fprintf(stderr, "[SASL-XOAUTH2] - filling prompts failed FAILED!\n");
return result;
}
return SASL_INTERACT;
}
/* FIXME: Fail if username is missing too? */
if (!token) {
PARAMERROR(params->utils);
return SASL_BADPARAM;
}
result = params->canon_user(utils->conn, authid, 0, SASL_CU_AUTHID | SASL_CU_AUTHZID, oparams);
if (result != SASL_OK) {
fprintf(stderr, "[SASL-XOAUTH2] - canon user FAILED!\n");
return result;
}
/* https://developers.google.com/gmail/xoauth2_protocol#the_sasl_xoauth2_mechanism */
*clientoutlen = 5 /* user=*/
+ ((authid && *authid) ? strlen(authid) : 0) /* %s */
+ 1 /* \001 */
+ 12 /* auth=Bearer{space} */
+ ((token && *token) ? strlen(token) : 0) /* %s */
+ 2; /* \001\001 */
/* remember the extra NUL on the end for stupid clients */
result = _plug_buf_alloc(params->utils, &(context->out_buf), &(context->out_buf_len), *clientoutlen + 1);
if (result != SASL_OK) {
fprintf(stderr, "[SASL-XOAUTH2] - _plug_buf_alloc FAILED!\n");
return result;
}
snprintf(context->out_buf, context->out_buf_len, "user=%s\1auth=Bearer %s\1\1", authid, token);
*clientout = context->out_buf;
/* set oparams */
oparams->doneflag = 1;
oparams->mech_ssf = 0;
oparams->maxoutbuf = 0;
oparams->encode_context = NULL;
oparams->encode = NULL;
oparams->decode_context = NULL;
oparams->decode = NULL;
oparams->param_version = 0;
return SASL_OK;
}
static void xoauth2_client_mech_dispose(void *conn_context, const sasl_utils_t *utils)
{
client_context_t *context = (client_context_t *)conn_context;
if (!context) {
return;
}
if (context->out_buf) {
utils->free(context->out_buf);
}
utils->free(context);
}
static sasl_client_plug_t xoauth2_client_plugins[] = {{
"XOAUTH2", /* mech_name */
0, /* max_ssf */
SASL_SEC_NOANONYMOUS | SASL_SEC_PASS_CREDENTIALS, /* security_flags */
SASL_FEAT_WANT_CLIENT_FIRST | SASL_FEAT_ALLOWS_PROXY, /* features */
NULL, /* required_prompts */
NULL, /* glob_context */
&xoauth2_client_mech_new, /* mech_new */
&xoauth2_client_mech_step, /* mech_step */
&xoauth2_client_mech_dispose, /* mech_dispose */
NULL, /* mech_free */
NULL, /* idle */
NULL, /* spare */
NULL /* spare */
}};
int xoauth2_client_plug_init(sasl_utils_t *utils, int maxversion, int *out_version, sasl_client_plug_t **pluglist, int *plugcount)
{
if (maxversion < SASL_CLIENT_PLUG_VERSION) {
SETERROR(utils, "XOAUTH2 version mismatch");
return SASL_BADVERS;
}
*out_version = SASL_CLIENT_PLUG_VERSION;
*pluglist = xoauth2_client_plugins;
*plugcount = 1;
return SASL_OK;
}
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