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f1d915ea49
curl/lib/socks_gssapi.c
Daniel Stenberg dcd6f81025
snprintf: renamed and we now only use msnprintf() 
The function does not return the same value as snprintf() normally does,
so readers may be mislead into thinking the code works differently than
it actually does. A different function name makes this easier to detect.

Reported-by: Tomas Hoger
Assisted-by: Daniel Gustafsson
Fixes #3296
Closes #3297
2018-11-23 08:26:51 +01:00

528 lines
20 KiB
C
Raw Blame History

/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2009, Markus Moeller, <markus_moeller@compuserve.com>
* Copyright (C) 2012 - 2018, 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.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.
*
***************************************************************************/
#include "curl_setup.h"
#if defined(HAVE_GSSAPI) && !defined(CURL_DISABLE_PROXY)
#include "curl_gssapi.h"
#include "urldata.h"
#include "sendf.h"
#include "connect.h"
#include "timeval.h"
#include "socks.h"
#include "warnless.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
static gss_ctx_id_t gss_context = GSS_C_NO_CONTEXT;
/*
* 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;
char buf[1024];
size_t len;
len = 0;
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(sizeof(buf) > len + status_string.length + 1) {
strcpy(buf + len, (char *) status_string.value);
len += status_string.length;
}
gss_release_buffer(&min_stat, &status_string);
break;
}
gss_release_buffer(&min_stat, &status_string);
}
if(sizeof(buf) > len + 3) {
strcpy(buf + len, ".\n");
len += 2;
}
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(sizeof(buf) > len + status_string.length)
strcpy(buf + len, (char *) status_string.value);
gss_release_buffer(&min_stat, &status_string);
break;
}
gss_release_buffer(&min_stat, &status_string);
}
failf(data, "GSS-API error: %s failed:\n%s", function, buf);
return 1;
}
return 0;
}
CURLcode Curl_SOCKS5_gssapi_negotiate(int sockindex,
struct connectdata *conn)
{
struct Curl_easy *data = conn->data;
curl_socket_t sock = conn->sock[sockindex];
CURLcode code;
ssize_t actualread;
ssize_t written;
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;
char *user = NULL;
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-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 = malloc(service.length);
if(!service.value)
return CURLE_OUT_OF_MEMORY;
memcpy(service.value, serviceptr, service.length);
gss_major_status = gss_import_name(&gss_minor_status, &service,
(gss_OID) GSS_C_NULL_OID, &server);
}
else {
service.value = 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;
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);
}
gss_release_buffer(&gss_status, &service); /* clear allocated memory */
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;
}
/* As long as we need to keep sending some context info, and there's 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)
gss_release_buffer(&gss_status, &gss_recv_token);
if(check_gss_err(data, gss_major_status,
gss_minor_status, "gss_init_sec_context")) {
gss_release_name(&gss_status, &server);
gss_release_buffer(&gss_status, &gss_recv_token);
gss_release_buffer(&gss_status, &gss_send_token);
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 != 0) {
socksreq[0] = 1; /* GSS-API subnegotiation version */
socksreq[1] = 1; /* authentication message type */
us_length = htons((short)gss_send_token.length);
memcpy(socksreq + 2, &us_length, sizeof(short));
code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
if(code || (4 != written)) {
failf(data, "Failed to send GSS-API authentication request.");
gss_release_name(&gss_status, &server);
gss_release_buffer(&gss_status, &gss_recv_token);
gss_release_buffer(&gss_status, &gss_send_token);
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
code = Curl_write_plain(conn, sock, (char *)gss_send_token.value,
gss_send_token.length, &written);
if(code || ((ssize_t)gss_send_token.length != written)) {
failf(data, "Failed to send GSS-API authentication token.");
gss_release_name(&gss_status, &server);
gss_release_buffer(&gss_status, &gss_recv_token);
gss_release_buffer(&gss_status, &gss_send_token);
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
}
gss_release_buffer(&gss_status, &gss_send_token);
gss_release_buffer(&gss_status, &gss_recv_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(conn, sock, (char *)socksreq, 4, &actualread);
if(result || (actualread != 4)) {
failf(data, "Failed to receive GSS-API authentication response.");
gss_release_name(&gss_status, &server);
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);
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
if(socksreq[1] != 1) { /* status / messgae type */
failf(data, "Invalid GSS-API authentication response type (%d %d).",
socksreq[0], socksreq[1]);
gss_release_name(&gss_status, &server);
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 = malloc(us_length);
if(!gss_recv_token.value) {
failf(data,
"Could not allocate memory for GSS-API authentication "
"response token.");
gss_release_name(&gss_status, &server);
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OUT_OF_MEMORY;
}
result = Curl_blockread_all(conn, sock, (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);
gss_release_buffer(&gss_status, &gss_recv_token);
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")) {
gss_delete_sec_context(&gss_status, &gss_context, NULL);
gss_release_name(&gss_status, &gss_client_name);
failf(data, "Failed to determine user name.");
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")) {
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 user name.");
return CURLE_COULDNT_CONNECT;
}
user = malloc(gss_send_token.length + 1);
if(!user) {
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);
return CURLE_OUT_OF_MEMORY;
}
memcpy(user, gss_send_token.value, gss_send_token.length);
user[gss_send_token.length] = '\0';
gss_release_name(&gss_status, &gss_client_name);
gss_release_buffer(&gss_status, &gss_send_token);
infof(data, "SOCKS5 server authencticated user %s with GSS-API.\n",user);
free(user);
user = NULL;
/* 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.\n",
(gss_enc == 0)?"no":((gss_enc==1)?"integrity":"confidentiality"));
/* force for the moment to no data protection */
gss_enc = 0;
/*
* 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 = malloc(1);
if(!gss_send_token.value) {
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OUT_OF_MEMORY;
}
memcpy(gss_send_token.value, &gss_enc, 1);
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")) {
gss_release_buffer(&gss_status, &gss_send_token);
gss_release_buffer(&gss_status, &gss_w_token);
gss_delete_sec_context(&gss_status, &gss_context, NULL);
failf(data, "Failed to wrap GSS-API encryption value into token.");
return CURLE_COULDNT_CONNECT;
}
gss_release_buffer(&gss_status, &gss_send_token);
us_length = htons((short)gss_w_token.length);
memcpy(socksreq + 2, &us_length, sizeof(short));
}
code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
if(code || (4 != written)) {
failf(data, "Failed to send GSS-API encryption request.");
gss_release_buffer(&gss_status, &gss_w_token);
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_write_plain(conn, sock, socksreq, 1, &written);
if(code || ( 1 != written)) {
failf(data, "Failed to send GSS-API encryption type.");
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
}
else {
code = Curl_write_plain(conn, sock, (char *)gss_w_token.value,
gss_w_token.length, &written);
if(code || ((ssize_t)gss_w_token.length != written)) {
failf(data, "Failed to send GSS-API encryption type.");
gss_release_buffer(&gss_status, &gss_w_token);
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(conn, sock, (char *)socksreq, 4, &actualread);
if(result || (actualread != 4)) {
failf(data, "Failed to receive GSS-API encryption response.");
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_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
if(socksreq[1] != 2) { /* status / messgae type */
failf(data, "Invalid GSS-API encryption response type (%d %d).",
socksreq[0], socksreq[1]);
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 = malloc(gss_recv_token.length);
if(!gss_recv_token.value) {
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OUT_OF_MEMORY;
}
result = Curl_blockread_all(conn, sock, (char *)gss_recv_token.value,
gss_recv_token.length, &actualread);
if(result || (actualread != us_length)) {
failf(data, "Failed to receive GSS-API encryptrion type.");
gss_release_buffer(&gss_status, &gss_recv_token);
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")) {
gss_release_buffer(&gss_status, &gss_recv_token);
gss_release_buffer(&gss_status, &gss_w_token);
gss_delete_sec_context(&gss_status, &gss_context, NULL);
failf(data, "Failed to unwrap GSS-API encryption value into token.");
return CURLE_COULDNT_CONNECT;
}
gss_release_buffer(&gss_status, &gss_recv_token);
if(gss_w_token.length != 1) {
failf(data, "Invalid GSS-API encryption response length (%d).",
gss_w_token.length);
gss_release_buffer(&gss_status, &gss_w_token);
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 (%d).",
gss_recv_token.length);
gss_release_buffer(&gss_status, &gss_recv_token);
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_COULDNT_CONNECT;
}
memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
gss_release_buffer(&gss_status, &gss_recv_token);
}
infof(data, "SOCKS5 access with%s protection granted.\n",
(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)
gss_delete_sec_context(&gss_status, &gss_context, NULL);
return CURLE_OK;
}
#endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */
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