/* $Cambridge: exim/exim-src/src/auths/spa.c,v 1.9 2007/01/08 10:50:19 ph10 Exp $ */
/*************************************************
* Exim - an Internet mail transport agent *
*************************************************/
/* Copyright (c) University of Cambridge 1995 - 2007 */
/* See the file NOTICE for conditions of use and distribution. */
/* This file, which provides support for Microsoft's Secure Password
Authentication, was contributed by Marc Prud'hommeaux. Tom Kistner added SPA
server support. I (PH) have only modified it in very trivial ways.
References:
http://www.innovation.ch/java/ntlm.html
http://www.kuro5hin.org/story/2002/4/28/1436/66154
* It seems that some systems have existing but different definitions of some
* of the following types. I received a complaint about "int16" causing
* compilation problems. So I (PH) have renamed them all, to be on the safe
* side, by adding 'x' on the end. See auths/auth-spa.h.
* typedef signed short int16;
* typedef unsigned short uint16;
* typedef unsigned uint32;
* typedef unsigned char uint8;
07-August-2003: PH: Patched up the code to avoid assert bombouts for stupid
input data. Find appropriate comment by grepping for "PH".
16-October-2006: PH: Added a call to auth_check_serv_cond() at the end
*/
#include "../exim.h"
#include "spa.h"
/* #define DEBUG_SPA */
#ifdef DEBUG_SPA
#define DSPA(x,y,z) debug_printf(x,y,z)
#else
#define DSPA(x,y,z)
#endif
/* Options specific to the spa authentication mechanism. */
optionlist auth_spa_options[] = {
{ "client_domain", opt_stringptr,
(void *)(offsetof(auth_spa_options_block, spa_domain)) },
{ "client_password", opt_stringptr,
(void *)(offsetof(auth_spa_options_block, spa_password)) },
{ "client_username", opt_stringptr,
(void *)(offsetof(auth_spa_options_block, spa_username)) },
{ "server_password", opt_stringptr,
(void *)(offsetof(auth_spa_options_block, spa_serverpassword)) }
};
/* Size of the options list. An extern variable has to be used so that its
address can appear in the tables drtables.c. */
int auth_spa_options_count =
sizeof(auth_spa_options)/sizeof(optionlist);
/* Default private options block for the contidion authentication method. */
auth_spa_options_block auth_spa_option_defaults = {
NULL, /* spa_password */
NULL, /* spa_username */
NULL, /* spa_domain */
NULL /* spa_serverpassword (for server side use) */
};
/*************************************************
* Initialization entry point *
*************************************************/
/* Called for each instance, after its options have been read, to
enable consistency checks to be done, or anything else that needs
to be set up. */
void
auth_spa_init(auth_instance *ablock)
{
auth_spa_options_block *ob =
(auth_spa_options_block *)(ablock->options_block);
/* The public name defaults to the authenticator name */
if (ablock->public_name == NULL) ablock->public_name = ablock->name;
/* Both username and password must be set for a client */
if ((ob->spa_username == NULL) != (ob->spa_password == NULL))
log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:\n "
"one of client_username and client_password cannot be set without "
"the other", ablock->name);
ablock->client = ob->spa_username != NULL;
/* For a server we have just one option */
ablock->server = ob->spa_serverpassword != NULL;
}
/*************************************************
* Server entry point *
*************************************************/
/* For interface, see auths/README */
#define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
#define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
#define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
#define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)
int
auth_spa_server(auth_instance *ablock, uschar *data)
{
auth_spa_options_block *ob = (auth_spa_options_block *)(ablock->options_block);
uint8x lmRespData[24];
uint8x ntRespData[24];
SPAAuthRequest request;
SPAAuthChallenge challenge;
SPAAuthResponse response;
SPAAuthResponse *responseptr = &response;
uschar msgbuf[2048];
uschar *clearpass;
/* send a 334, MS Exchange style, and grab the client's request */
if (auth_get_no64_data(&data, US"NTLM supported") != OK)
{
/* something borked */
return FAIL;
}
if (spa_base64_to_bits((char *)(&request), sizeof(request), (const char *)(data)) < 0)
{
DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
"request: %s\n", data);
return FAIL;
}
/* create a challenge and send it back */
spa_build_auth_challenge(&request,&challenge);
spa_bits_to_base64 (msgbuf, (unsigned char*)&challenge,
spa_request_length(&challenge));
if (auth_get_no64_data(&data, msgbuf) != OK)
{
/* something borked */
return FAIL;
}
/* dump client response */
if (spa_base64_to_bits((char *)(&response), sizeof(response), (const char *)(data)) < 0)
{
DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
"response: %s\n", data);
return FAIL;
}
/***************************************************************
PH 07-Aug-2003: The original code here was this:
Ustrcpy(msgbuf, unicodeToString(((char*)responseptr) +
IVAL(&responseptr->uUser.offset,0),
SVAL(&responseptr->uUser.len,0)/2) );
However, if the response data is too long, unicodeToString bombs out on
an assertion failure. It uses a 1024 fixed buffer. Bombing out is not a good
idea. It's too messy to try to rework that function to return an error because
it is called from a number of other places in the auth-spa.c module. Instead,
since it is a very small function, I reproduce its code here, with a size check
that causes failure if the size of msgbuf is exceeded. ****/
{
int i;
char *p = ((char*)responseptr) + IVAL(&responseptr->uUser.offset,0);
int len = SVAL(&responseptr->uUser.len,0)/2;
if (len + 1 >= sizeof(msgbuf)) return FAIL;
for (i = 0; i < len; ++i)
{
msgbuf[i] = *p & 0x7f;
p += 2;
}
msgbuf[i] = 0;
}
/***************************************************************/
/* Put the username in $auth1 and $1. The former is now the preferred variable;
the latter is the original variable. */
auth_vars[0] = expand_nstring[1] = msgbuf;
expand_nlength[1] = Ustrlen(msgbuf);
expand_nmax = 1;
debug_print_string(ablock->server_debug_string); /* customized debug */
/* look up password */
clearpass = expand_string(ob->spa_serverpassword);
if (clearpass == NULL)
{
if (expand_string_forcedfail)
{
DEBUG(D_auth) debug_printf("auth_spa_server(): forced failure while "
"expanding spa_serverpassword\n");
return FAIL;
}
else
{
DEBUG(D_auth) debug_printf("auth_spa_server(): error while expanding "
"spa_serverpassword: %s\n", expand_string_message);
return DEFER;
}
}
/* create local hash copy */
spa_smb_encrypt (clearpass, challenge.challengeData, lmRespData);
spa_smb_nt_encrypt (clearpass, challenge.challengeData, ntRespData);
/* compare NT hash (LM may not be available) */
if (memcmp(ntRespData,
((unsigned char*)responseptr)+IVAL(&responseptr->ntResponse.offset,0),
24) == 0)
/* success. we have a winner. */
/* Expand server_condition as an authorization check (PH) */
return auth_check_serv_cond(ablock);
return FAIL;
}
/*************************************************
* Client entry point *
*************************************************/
/* For interface, see auths/README */
int
auth_spa_client(
auth_instance *ablock, /* authenticator block */
smtp_inblock *inblock, /* connection inblock */
smtp_outblock *outblock, /* connection outblock */
int timeout, /* command timeout */
uschar *buffer, /* buffer for reading response */
int buffsize) /* size of buffer */
{
auth_spa_options_block *ob =
(auth_spa_options_block *)(ablock->options_block);
SPAAuthRequest request;
SPAAuthChallenge challenge;
SPAAuthResponse response;
char msgbuf[2048];
char *domain = NULL;
char *username, *password;
/* Code added by PH to expand the options */
*buffer = 0; /* Default no message when cancelled */
username = CS expand_string(ob->spa_username);
if (username == NULL)
{
if (expand_string_forcedfail) return CANCELLED;
string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
"authenticator: %s", ob->spa_username, ablock->name,
expand_string_message);
return ERROR;
}
password = CS expand_string(ob->spa_password);
if (password == NULL)
{
if (expand_string_forcedfail) return CANCELLED;
string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
"authenticator: %s", ob->spa_password, ablock->name,
expand_string_message);
return ERROR;
}
if (ob->spa_domain != NULL)
{
domain = CS expand_string(ob->spa_domain);
if (domain == NULL)
{
if (expand_string_forcedfail) return CANCELLED;
string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
"authenticator: %s", ob->spa_domain, ablock->name,
expand_string_message);
return ERROR;
}
}
/* Original code */
if (smtp_write_command(outblock, FALSE, "AUTH %s\r\n",
ablock->public_name) < 0)
return FAIL_SEND;
/* wait for the 3XX OK message */
if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
return FAIL;
DSPA("\n\n%s authenticator: using domain %s\n\n",
ablock->name, domain);
spa_build_auth_request (&request, CS username, domain);
spa_bits_to_base64 (US msgbuf, (unsigned char*)&request,
spa_request_length(&request));
DSPA("\n\n%s authenticator: sending request (%s)\n\n", ablock->name,
msgbuf);
/* send the encrypted password */
if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
return FAIL_SEND;
/* wait for the auth challenge */
if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
return FAIL;
/* convert the challenge into the challenge struct */
DSPA("\n\n%s authenticator: challenge (%s)\n\n",
ablock->name, buffer + 4);
spa_base64_to_bits ((char *)(&challenge), sizeof(challenge), (const char *)(buffer + 4));
spa_build_auth_response (&challenge, &response,
CS username, CS password);
spa_bits_to_base64 (US msgbuf, (unsigned char*)&response,
spa_request_length(&response));
DSPA("\n\n%s authenticator: challenge response (%s)\n\n", ablock->name,
msgbuf);
/* send the challenge response */
if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
return FAIL_SEND;
/* If we receive a success response from the server, authentication
has succeeded. There may be more data to send, but is there any point
in provoking an error here? */
if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout))
return OK;
/* Not a success response. If errno != 0 there is some kind of transmission
error. Otherwise, check the response code in the buffer. If it starts with
'3', more data is expected. */
if (errno != 0 || buffer[0] != '3')
return FAIL;
return FAIL;
}
/* End of spa.c */
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