branch: master
socks_gssapi.c
20159 bytesRaw
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
* Copyright (C) Markus Moeller, <markus_moeller@compuserve.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.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
#include "curl_setup.h"
#if defined(HAVE_GSSAPI) && !defined(CURL_DISABLE_PROXY)
#include "curl_gssapi.h"
#include "urldata.h"
#include "curl_trc.h"
#include "cfilters.h"
#include "connect.h"
#include "curlx/nonblock.h"
#include "socks.h"
#include "curlx/strdup.h"
#if defined(CURL_HAVE_DIAG) && defined(__APPLE__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#endif
#define MAX_GSS_LEN 1024
/*
* Helper GSS-API error functions.
*/
static int check_gss_err(struct Curl_easy *data,
OM_uint32 major_status,
OM_uint32 minor_status,
const char *function)
{
if(GSS_ERROR(major_status)) {
OM_uint32 maj_stat, min_stat;
OM_uint32 msg_ctx = 0;
gss_buffer_desc status_string = GSS_C_EMPTY_BUFFER;
struct dynbuf dbuf;
curlx_dyn_init(&dbuf, MAX_GSS_LEN);
msg_ctx = 0;
while(!msg_ctx) {
/* convert major status code (GSS-API error) to text */
maj_stat = gss_display_status(&min_stat, major_status,
GSS_C_GSS_CODE,
GSS_C_NULL_OID,
&msg_ctx, &status_string);
if(maj_stat == GSS_S_COMPLETE) {
if(curlx_dyn_addn(&dbuf, status_string.value, status_string.length))
return 1; /* error */
gss_release_buffer(&min_stat, &status_string);
break;
}
gss_release_buffer(&min_stat, &status_string);
}
if(curlx_dyn_addn(&dbuf, ".\n", 2))
return 1; /* error */
msg_ctx = 0;
while(!msg_ctx) {
/* convert minor status code (underlying routine error) to text */
maj_stat = gss_display_status(&min_stat, minor_status,
GSS_C_MECH_CODE,
GSS_C_NULL_OID,
&msg_ctx, &status_string);
if(maj_stat == GSS_S_COMPLETE) {
if(curlx_dyn_addn(&dbuf, status_string.value, status_string.length))
return 1; /* error */
gss_release_buffer(&min_stat, &status_string);
break;
}
gss_release_buffer(&min_stat, &status_string);
}
failf(data, "GSS-API error: %s failed: %s", function,
curlx_dyn_ptr(&dbuf));
curlx_dyn_free(&dbuf);
return 1;
}
return 0;
}
CURLcode Curl_SOCKS5_gssapi_negotiate(struct Curl_cfilter *cf,
struct Curl_easy *data)
{
struct connectdata *conn = cf->conn;
curl_socket_t sock = conn->sock[cf->sockindex];
CURLcode code;
size_t actualread;
size_t nwritten;
int result;
OM_uint32 gss_major_status, gss_minor_status, gss_status;
OM_uint32 gss_ret_flags;
int gss_conf_state, gss_enc;
gss_buffer_desc service = GSS_C_EMPTY_BUFFER;
gss_buffer_desc gss_send_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc gss_recv_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc gss_w_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc *gss_token = GSS_C_NO_BUFFER;
gss_name_t server = GSS_C_NO_NAME;
gss_name_t gss_client_name = GSS_C_NO_NAME;
unsigned short us_length;
unsigned char socksreq[4]; /* room for GSS-API exchange header only */
const char *serviceptr = data->set.str[STRING_PROXY_SERVICE_NAME] ?
data->set.str[STRING_PROXY_SERVICE_NAME] : "rcmd";
const size_t serviceptr_length = strlen(serviceptr);
gss_ctx_id_t gss_context = GSS_C_NO_CONTEXT;
/* GSS-API request looks like
* +----+------+-----+----------------+
* |VER | MTYP | LEN | TOKEN |
* +----+------+----------------------+
* | 1 | 1 | 2 | up to 2^16 - 1 |
* +----+------+-----+----------------+
*/
/* prepare service name */
if(strchr(serviceptr, '/')) {
service.length = serviceptr_length;
service.value = curlx_memdup(serviceptr, service.length);
if(!service.value)
return CURLE_OUT_OF_MEMORY;
gss_major_status = gss_import_name(&gss_minor_status, &service,
(gss_OID)GSS_C_NULL_OID, &server);
}
else {
service.value = curlx_malloc(serviceptr_length +
strlen(conn->socks_proxy.host.name) + 2);
if(!service.value)
return CURLE_OUT_OF_MEMORY;
service.length = serviceptr_length +
strlen(conn->socks_proxy.host.name) + 1;
curl_msnprintf(service.value, service.length + 1, "%s@%s",
serviceptr, conn->socks_proxy.host.name);
gss_major_status = gss_import_name(&gss_minor_status, &service,
GSS_C_NT_HOSTBASED_SERVICE, &server);
}
Curl_safefree(service.value);
service.length = 0;
if(check_gss_err(data, gss_major_status,
gss_minor_status, "gss_import_name()")) {
failf(data, "Failed to create service name.");
gss_release_name(&gss_status, &server);
return CURLE_COULDNT_CONNECT;
}
(void)curlx_nonblock(sock, FALSE);
/* As long as we need to keep sending some context info, and there is no
* errors, keep sending it... */
for(;;) {
gss_major_status = Curl_gss_init_sec_context(data,
&gss_minor_status,
&gss_context,
server,
&Curl_krb5_mech_oid,
NULL,
gss_token,
&gss_send_token,
TRUE,
&gss_ret_flags);
if(gss_token != GSS_C_NO_BUFFER) {
Curl_safefree(gss_recv_token.value);
gss_recv_token.length = 0;
}
if(check_gss_err(data, gss_major_status,
gss_minor_status, "gss_init_sec_context") ||
/* the size needs to fit in a 16-bit field */
(gss_send_token.length > 0xffff)) {
gss_release_name(&gss_status, &server);
gss_release_buffer(&gss_status, &gss_send_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
failf(data, "Failed to initial GSS-API token.");
return CURLE_COULDNT_CONNECT;
}
if(gss_send_token.length) {
socksreq[0] = 1; /* GSS-API subnegotiation version */
socksreq[1] = 1; /* authentication message type */
us_length = htons((unsigned short)gss_send_token.length);
memcpy(socksreq + 2, &us_length, sizeof(short));
code = Curl_conn_cf_send(cf->next, data, socksreq, 4, FALSE, &nwritten);
if(code || (nwritten != 4)) {
failf(data, "Failed to send GSS-API authentication request.");
gss_release_name(&gss_status, &server);
gss_release_buffer(&gss_status, &gss_send_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
code = Curl_conn_cf_send(cf->next, data,
gss_send_token.value,
gss_send_token.length, FALSE, &nwritten);
if(code || (gss_send_token.length != nwritten)) {
failf(data, "Failed to send GSS-API authentication token.");
gss_release_name(&gss_status, &server);
gss_release_buffer(&gss_status, &gss_send_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
}
gss_release_buffer(&gss_status, &gss_send_token);
if(gss_major_status != GSS_S_CONTINUE_NEEDED)
break;
/* analyse response */
/* GSS-API response looks like
* +----+------+-----+----------------+
* |VER | MTYP | LEN | TOKEN |
* +----+------+----------------------+
* | 1 | 1 | 2 | up to 2^16 - 1 |
* +----+------+-----+----------------+
*/
result = Curl_blockread_all(cf, data, (char *)socksreq, 4, &actualread);
if(result || (actualread != 4)) {
failf(data, "Failed to receive GSS-API authentication response.");
gss_release_name(&gss_status, &server);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
/* ignore the first (VER) byte */
if(socksreq[1] == 255) { /* status / message type */
failf(data, "User was rejected by the SOCKS5 server (%d %d).",
socksreq[0], socksreq[1]);
gss_release_name(&gss_status, &server);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
if(socksreq[1] != 1) { /* status / message type */
failf(data, "Invalid GSS-API authentication response type (%d %d).",
socksreq[0], socksreq[1]);
gss_release_name(&gss_status, &server);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
memcpy(&us_length, socksreq + 2, sizeof(short));
us_length = ntohs(us_length);
gss_recv_token.length = us_length;
gss_recv_token.value = curlx_malloc(gss_recv_token.length);
if(!gss_recv_token.value) {
failf(data,
"Could not allocate memory for GSS-API authentication "
"response token.");
gss_release_name(&gss_status, &server);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OUT_OF_MEMORY;
}
result = Curl_blockread_all(cf, data, (char *)gss_recv_token.value,
gss_recv_token.length, &actualread);
if(result || (actualread != us_length)) {
failf(data, "Failed to receive GSS-API authentication token.");
gss_release_name(&gss_status, &server);
Curl_safefree(gss_recv_token.value);
gss_recv_token.length = 0;
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
gss_token = &gss_recv_token;
}
gss_release_name(&gss_status, &server);
/* Everything is good so far, user was authenticated! */
gss_major_status = gss_inquire_context(&gss_minor_status, gss_context,
&gss_client_name, NULL, NULL, NULL,
NULL, NULL, NULL);
if(check_gss_err(data, gss_major_status,
gss_minor_status, "gss_inquire_context")) {
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
gss_release_name(&gss_status, &gss_client_name);
failf(data, "Failed to determine username.");
return CURLE_COULDNT_CONNECT;
}
gss_major_status = gss_display_name(&gss_minor_status, gss_client_name,
&gss_send_token, NULL);
if(check_gss_err(data, gss_major_status,
gss_minor_status, "gss_display_name")) {
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
gss_release_name(&gss_status, &gss_client_name);
gss_release_buffer(&gss_status, &gss_send_token);
failf(data, "Failed to determine username.");
return CURLE_COULDNT_CONNECT;
}
infof(data, "SOCKS5 server authenticated user %.*s with GSS-API.",
(int)gss_send_token.length, (const char *)gss_send_token.value);
gss_release_name(&gss_status, &gss_client_name);
gss_release_buffer(&gss_status, &gss_send_token);
/* Do encryption */
socksreq[0] = 1; /* GSS-API subnegotiation version */
socksreq[1] = 2; /* encryption message type */
gss_enc = 0; /* no data protection */
/* do confidentiality protection if supported */
if(gss_ret_flags & GSS_C_CONF_FLAG)
gss_enc = 2;
/* else do integrity protection */
else if(gss_ret_flags & GSS_C_INTEG_FLAG)
gss_enc = 1;
infof(data, "SOCKS5 server supports GSS-API %s data protection.",
(gss_enc == 0) ? "no" :
((gss_enc == 1) ? "integrity" : "confidentiality"));
/*
* Sending the encryption type in clear seems wrong. It should be
* protected with gss_seal()/gss_wrap(). See RFC1961 extract below
* The NEC reference implementations on which this is based is
* therefore at fault
*
* +------+------+------+.......................+
* + ver | mtyp | len | token |
* +------+------+------+.......................+
* + 0x01 | 0x02 | 0x02 | up to 2^16 - 1 octets |
* +------+------+------+.......................+
*
* Where:
*
* - "ver" is the protocol version number, here 1 to represent the
* first version of the SOCKS/GSS-API protocol
*
* - "mtyp" is the message type, here 2 to represent a protection
* -level negotiation message
*
* - "len" is the length of the "token" field in octets
*
* - "token" is the GSS-API encapsulated protection level
*
* The token is produced by encapsulating an octet containing the
* required protection level using gss_seal()/gss_wrap() with conf_req
* set to FALSE. The token is verified using gss_unseal()/
* gss_unwrap().
*
*/
if(data->set.socks5_gssapi_nec) {
us_length = htons((short)1);
memcpy(socksreq + 2, &us_length, sizeof(short));
}
else {
gss_send_token.length = 1;
gss_send_token.value = curlx_memdup(&gss_enc, gss_send_token.length);
if(!gss_send_token.value) {
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OUT_OF_MEMORY;
}
gss_major_status = gss_wrap(&gss_minor_status, gss_context, 0,
GSS_C_QOP_DEFAULT, &gss_send_token,
&gss_conf_state, &gss_w_token);
if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_wrap")) {
Curl_safefree(gss_send_token.value);
gss_send_token.length = 0;
gss_release_buffer(&gss_status, &gss_w_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
failf(data, "Failed to wrap GSS-API encryption value into token.");
return CURLE_COULDNT_CONNECT;
}
Curl_safefree(gss_send_token.value);
gss_send_token.length = 0;
us_length = htons((unsigned short)gss_w_token.length);
memcpy(socksreq + 2, &us_length, sizeof(short));
}
code = Curl_conn_cf_send(cf->next, data, socksreq, 4, FALSE, &nwritten);
if(code || (nwritten != 4)) {
failf(data, "Failed to send GSS-API encryption request.");
gss_release_buffer(&gss_status, &gss_w_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
if(data->set.socks5_gssapi_nec) {
memcpy(socksreq, &gss_enc, 1);
code = Curl_conn_cf_send(cf->next, data, socksreq, 1, FALSE, &nwritten);
if(code || (nwritten != 1)) {
failf(data, "Failed to send GSS-API encryption type.");
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
}
else {
code = Curl_conn_cf_send(cf->next, data, gss_w_token.value,
gss_w_token.length, FALSE, &nwritten);
if(code || (gss_w_token.length != nwritten)) {
failf(data, "Failed to send GSS-API encryption type.");
gss_release_buffer(&gss_status, &gss_w_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
gss_release_buffer(&gss_status, &gss_w_token);
}
result = Curl_blockread_all(cf, data, (char *)socksreq, 4, &actualread);
if(result || (actualread != 4)) {
failf(data, "Failed to receive GSS-API encryption response.");
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
/* ignore the first (VER) byte */
if(socksreq[1] == 255) { /* status / message type */
failf(data, "User was rejected by the SOCKS5 server (%d %d).",
socksreq[0], socksreq[1]);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
if(socksreq[1] != 2) { /* status / message type */
failf(data, "Invalid GSS-API encryption response type (%d %d).",
socksreq[0], socksreq[1]);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
memcpy(&us_length, socksreq + 2, sizeof(short));
us_length = ntohs(us_length);
gss_recv_token.length = us_length;
gss_recv_token.value = curlx_malloc(gss_recv_token.length);
if(!gss_recv_token.value) {
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OUT_OF_MEMORY;
}
result = Curl_blockread_all(cf, data, (char *)gss_recv_token.value,
gss_recv_token.length, &actualread);
if(result || (actualread != us_length)) {
failf(data, "Failed to receive GSS-API encryption type.");
Curl_safefree(gss_recv_token.value);
gss_recv_token.length = 0;
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
if(!data->set.socks5_gssapi_nec) {
gss_major_status = gss_unwrap(&gss_minor_status, gss_context,
&gss_recv_token, &gss_w_token,
0, GSS_C_QOP_DEFAULT);
if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_unwrap")) {
Curl_safefree(gss_recv_token.value);
gss_recv_token.length = 0;
gss_release_buffer(&gss_status, &gss_w_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
failf(data, "Failed to unwrap GSS-API encryption value into token.");
return CURLE_COULDNT_CONNECT;
}
Curl_safefree(gss_recv_token.value);
gss_recv_token.length = 0;
if(gss_w_token.length != 1) {
failf(data, "Invalid GSS-API encryption response length (%zu).",
gss_w_token.length);
gss_release_buffer(&gss_status, &gss_w_token);
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
memcpy(socksreq, gss_w_token.value, gss_w_token.length);
gss_release_buffer(&gss_status, &gss_w_token);
}
else {
if(gss_recv_token.length != 1) {
failf(data, "Invalid GSS-API encryption response length (%zu).",
gss_recv_token.length);
Curl_safefree(gss_recv_token.value);
gss_recv_token.length = 0;
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
Curl_safefree(gss_recv_token.value);
gss_recv_token.length = 0;
}
(void)curlx_nonblock(sock, TRUE);
infof(data, "SOCKS5 access with%s protection granted.",
(socksreq[0] == 0) ? "out GSS-API data" :
((socksreq[0] == 1) ? " GSS-API integrity" :
" GSS-API confidentiality"));
conn->socks5_gssapi_enctype = socksreq[0];
if(socksreq[0] == 0)
Curl_gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OK;
}
#if defined(CURL_HAVE_DIAG) && defined(__APPLE__)
#pragma GCC diagnostic pop
#endif
#endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */