1 /* $Cambridge: exim/src/src/auths/spa.c,v 1.3 2004/12/29 10:55:58 ph10 Exp $ */
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
7 /* Copyright (c) University of Cambridge 1995 - 2004 */
8 /* See the file NOTICE for conditions of use and distribution. */
10 /* This file, which provides support for Microsoft's Secure Password
11 Authentication, was contributed by Marc Prud'hommeaux. Tom Kistner added SPA
12 server support. I (PH) have only modified it in very trivial ways.
15 http://www.innovation.ch/java/ntlm.html
16 http://www.kuro5hin.org/story/2002/4/28/1436/66154
18 * It seems that some systems have existing but different definitions of some
19 * of the following types. I received a complaint about "int16" causing
20 * compilation problems. So I (PH) have renamed them all, to be on the safe
21 * side, by adding 'x' on the end. See auths/auth-spa.h.
23 * typedef signed short int16;
24 * typedef unsigned short uint16;
25 * typedef unsigned uint32;
26 * typedef unsigned char uint8;
28 07-August-2003: PH: Patched up the code to avoid assert bombouts for stupid
29 input data. Find appropriate comment by grepping for "PH".
36 /* #define DEBUG_SPA */
39 #define DSPA(x,y,z) debug_printf(x,y,z)
44 /* Options specific to the spa authentication mechanism. */
46 optionlist auth_spa_options[] = {
47 { "client_domain", opt_stringptr,
48 (void *)(offsetof(auth_spa_options_block, spa_domain)) },
49 { "client_password", opt_stringptr,
50 (void *)(offsetof(auth_spa_options_block, spa_password)) },
51 { "client_username", opt_stringptr,
52 (void *)(offsetof(auth_spa_options_block, spa_username)) },
53 { "server_password", opt_stringptr,
54 (void *)(offsetof(auth_spa_options_block, spa_serverpassword)) }
57 /* Size of the options list. An extern variable has to be used so that its
58 address can appear in the tables drtables.c. */
60 int auth_spa_options_count =
61 sizeof(auth_spa_options)/sizeof(optionlist);
63 /* Default private options block for the contidion authentication method. */
65 auth_spa_options_block auth_spa_option_defaults = {
66 NULL, /* spa_password */
67 NULL, /* spa_username */
68 NULL, /* spa_domain */
69 NULL /* spa_serverpassword (for server side use) */
73 /*************************************************
74 * Initialization entry point *
75 *************************************************/
77 /* Called for each instance, after its options have been read, to
78 enable consistency checks to be done, or anything else that needs
82 auth_spa_init(auth_instance *ablock)
84 auth_spa_options_block *ob =
85 (auth_spa_options_block *)(ablock->options_block);
87 /* The public name defaults to the authenticator name */
89 if (ablock->public_name == NULL) ablock->public_name = ablock->name;
91 /* Both username and password must be set for a client */
93 if ((ob->spa_username == NULL) != (ob->spa_password == NULL))
94 log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:\n "
95 "one of client_username and client_password cannot be set without "
96 "the other", ablock->name);
97 ablock->client = ob->spa_username != NULL;
99 /* For a server we have just one option */
101 ablock->server = ob->spa_serverpassword != NULL;
106 /*************************************************
107 * Server entry point *
108 *************************************************/
110 /* For interface, see auths/README */
112 #define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
113 #define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
114 #define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
115 #define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)
118 auth_spa_server(auth_instance *ablock, uschar *data)
120 auth_spa_options_block *ob = (auth_spa_options_block *)(ablock->options_block);
121 uint8x lmRespData[24];
122 uint8x ntRespData[24];
123 SPAAuthRequest request;
124 SPAAuthChallenge challenge;
125 SPAAuthResponse response;
126 SPAAuthResponse *responseptr = &response;
130 /* send a 334, MS Exchange style, and grab the client's request */
132 if (auth_get_no64_data(&data, US"NTLM supported") != OK)
134 /* something borked */
138 if (spa_base64_to_bits((char *)(&request), sizeof(request), (const char *)(data)) < 0)
140 DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
141 "request: %s\n", data);
145 /* create a challenge and send it back */
147 spa_build_auth_challenge(&request,&challenge);
148 spa_bits_to_base64 (msgbuf, (unsigned char*)&challenge,
149 spa_request_length(&challenge));
151 if (auth_get_no64_data(&data, msgbuf) != OK)
153 /* something borked */
157 /* dump client response */
158 if (spa_base64_to_bits((char *)(&response), sizeof(response), (const char *)(data)) < 0)
160 DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
161 "response: %s\n", data);
165 /* get username and put it in $1 */
167 /***************************************************************
168 PH 07-Aug-2003: The original code here was this:
170 Ustrcpy(msgbuf, unicodeToString(((char*)responseptr) +
171 IVAL(&responseptr->uUser.offset,0),
172 SVAL(&responseptr->uUser.len,0)/2) );
174 However, if the response data is too long, unicodeToString bombs out on
175 an assertion failure. It uses a 1024 fixed buffer. Bombing out is not a good
176 idea. It's too messy to try to rework that function to return an error because
177 it is called from a number of other places in the auth-spa.c module. Instead,
178 since it is a very small function, I reproduce its code here, with a size check
179 that causes failure if the size of msgbuf is exceeded. ****/
183 char *p = ((char*)responseptr) + IVAL(&responseptr->uUser.offset,0);
184 int len = SVAL(&responseptr->uUser.len,0)/2;
186 if (len + 1 >= sizeof(msgbuf)) return FAIL;
187 for (i = 0; i < len; ++i)
189 msgbuf[i] = *p & 0x7f;
195 /***************************************************************/
197 expand_nstring[1] = msgbuf;
198 expand_nlength[1] = Ustrlen(msgbuf);
201 /* look up password */
203 clearpass = expand_string(ob->spa_serverpassword);
204 if (clearpass == NULL)
206 if (expand_string_forcedfail)
208 DEBUG(D_auth) debug_printf("auth_spa_server(): forced failure while "
209 "expanding spa_serverpassword\n");
214 DEBUG(D_auth) debug_printf("auth_spa_server(): error while expanding "
215 "spa_serverpassword: %s\n", expand_string_message);
220 /* create local hash copy */
222 spa_smb_encrypt (clearpass, challenge.challengeData, lmRespData);
223 spa_smb_nt_encrypt (clearpass, challenge.challengeData, ntRespData);
225 /* compare NT hash (LM may not be available) */
227 if (memcmp(ntRespData,
228 ((unsigned char*)responseptr)+IVAL(&responseptr->ntResponse.offset,0),
230 /* success. we have a winner. */
237 /*************************************************
238 * Client entry point *
239 *************************************************/
241 /* For interface, see auths/README */
245 auth_instance *ablock, /* authenticator block */
246 smtp_inblock *inblock, /* connection inblock */
247 smtp_outblock *outblock, /* connection outblock */
248 int timeout, /* command timeout */
249 uschar *buffer, /* buffer for reading response */
250 int buffsize) /* size of buffer */
252 auth_spa_options_block *ob =
253 (auth_spa_options_block *)(ablock->options_block);
254 SPAAuthRequest request;
255 SPAAuthChallenge challenge;
256 SPAAuthResponse response;
259 char *username, *password;
261 /* Code added by PH to expand the options */
263 username = CS expand_string(ob->spa_username);
264 if (username == NULL)
266 if (expand_string_forcedfail) return CANCELLED;
267 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
268 "authenticator: %s", ob->spa_username, ablock->name,
269 expand_string_message);
273 password = CS expand_string(ob->spa_password);
274 if (password == NULL)
276 if (expand_string_forcedfail) return CANCELLED;
277 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
278 "authenticator: %s", ob->spa_password, ablock->name,
279 expand_string_message);
283 if (ob->spa_domain != NULL)
285 domain = CS expand_string(ob->spa_domain);
288 if (expand_string_forcedfail) return CANCELLED;
289 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
290 "authenticator: %s", ob->spa_domain, ablock->name,
291 expand_string_message);
298 if (smtp_write_command(outblock, FALSE, "AUTH %s\r\n",
299 ablock->public_name) < 0)
302 /* wait for the 3XX OK message */
303 if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
306 DSPA("\n\n%s authenticator: using domain %s\n\n",
307 ablock->name, domain);
309 spa_build_auth_request (&request, CS username, domain);
310 spa_bits_to_base64 (US msgbuf, (unsigned char*)&request,
311 spa_request_length(&request));
313 DSPA("\n\n%s authenticator: sending request (%s)\n\n", ablock->name,
316 /* send the encrypted password */
317 if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
320 /* wait for the auth challenge */
321 if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
324 /* convert the challenge into the challenge struct */
325 DSPA("\n\n%s authenticator: challenge (%s)\n\n",
326 ablock->name, buffer + 4);
327 spa_base64_to_bits ((char *)(&challenge), sizeof(challenge), (const char *)(buffer + 4));
329 spa_build_auth_response (&challenge, &response,
330 CS username, CS password);
331 spa_bits_to_base64 (US msgbuf, (unsigned char*)&response,
332 spa_request_length(&response));
333 DSPA("\n\n%s authenticator: challenge response (%s)\n\n", ablock->name,
336 /* send the challenge response */
337 if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
340 /* If we receive a success response from the server, authentication
341 has succeeded. There may be more data to send, but is there any point
342 in provoking an error here? */
343 if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout))
346 /* Not a success response. If errno != 0 there is some kind of transmission
347 error. Otherwise, check the response code in the buffer. If it starts with
348 '3', more data is expected. */
349 if (errno != 0 || buffer[0] != '3')