1 /* $Cambridge: exim/src/src/auths/spa.c,v 1.10 2009/11/16 19:50:38 nm4 Exp $ */
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
7 /* Copyright (c) University of Cambridge 1995 - 2009 */
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".
30 16-October-2006: PH: Added a call to auth_check_serv_cond() at the end
37 /* #define DEBUG_SPA */
40 #define DSPA(x,y,z) debug_printf(x,y,z)
45 /* Options specific to the spa authentication mechanism. */
47 optionlist auth_spa_options[] = {
48 { "client_domain", opt_stringptr,
49 (void *)(offsetof(auth_spa_options_block, spa_domain)) },
50 { "client_password", opt_stringptr,
51 (void *)(offsetof(auth_spa_options_block, spa_password)) },
52 { "client_username", opt_stringptr,
53 (void *)(offsetof(auth_spa_options_block, spa_username)) },
54 { "server_password", opt_stringptr,
55 (void *)(offsetof(auth_spa_options_block, spa_serverpassword)) }
58 /* Size of the options list. An extern variable has to be used so that its
59 address can appear in the tables drtables.c. */
61 int auth_spa_options_count =
62 sizeof(auth_spa_options)/sizeof(optionlist);
64 /* Default private options block for the contidion authentication method. */
66 auth_spa_options_block auth_spa_option_defaults = {
67 NULL, /* spa_password */
68 NULL, /* spa_username */
69 NULL, /* spa_domain */
70 NULL /* spa_serverpassword (for server side use) */
74 /*************************************************
75 * Initialization entry point *
76 *************************************************/
78 /* Called for each instance, after its options have been read, to
79 enable consistency checks to be done, or anything else that needs
83 auth_spa_init(auth_instance *ablock)
85 auth_spa_options_block *ob =
86 (auth_spa_options_block *)(ablock->options_block);
88 /* The public name defaults to the authenticator name */
90 if (ablock->public_name == NULL) ablock->public_name = ablock->name;
92 /* Both username and password must be set for a client */
94 if ((ob->spa_username == NULL) != (ob->spa_password == NULL))
95 log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:\n "
96 "one of client_username and client_password cannot be set without "
97 "the other", ablock->name);
98 ablock->client = ob->spa_username != NULL;
100 /* For a server we have just one option */
102 ablock->server = ob->spa_serverpassword != NULL;
107 /*************************************************
108 * Server entry point *
109 *************************************************/
111 /* For interface, see auths/README */
113 #define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
114 #define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
115 #define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
116 #define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)
119 auth_spa_server(auth_instance *ablock, uschar *data)
121 auth_spa_options_block *ob = (auth_spa_options_block *)(ablock->options_block);
122 uint8x lmRespData[24];
123 uint8x ntRespData[24];
124 SPAAuthRequest request;
125 SPAAuthChallenge challenge;
126 SPAAuthResponse response;
127 SPAAuthResponse *responseptr = &response;
131 /* send a 334, MS Exchange style, and grab the client's request */
133 if (auth_get_no64_data(&data, US"NTLM supported") != OK)
135 /* something borked */
139 if (spa_base64_to_bits((char *)(&request), sizeof(request), (const char *)(data)) < 0)
141 DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
142 "request: %s\n", data);
146 /* create a challenge and send it back */
148 spa_build_auth_challenge(&request,&challenge);
149 spa_bits_to_base64 (msgbuf, (unsigned char*)&challenge,
150 spa_request_length(&challenge));
152 if (auth_get_no64_data(&data, msgbuf) != OK)
154 /* something borked */
158 /* dump client response */
159 if (spa_base64_to_bits((char *)(&response), sizeof(response), (const char *)(data)) < 0)
161 DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
162 "response: %s\n", data);
166 /***************************************************************
167 PH 07-Aug-2003: The original code here was this:
169 Ustrcpy(msgbuf, unicodeToString(((char*)responseptr) +
170 IVAL(&responseptr->uUser.offset,0),
171 SVAL(&responseptr->uUser.len,0)/2) );
173 However, if the response data is too long, unicodeToString bombs out on
174 an assertion failure. It uses a 1024 fixed buffer. Bombing out is not a good
175 idea. It's too messy to try to rework that function to return an error because
176 it is called from a number of other places in the auth-spa.c module. Instead,
177 since it is a very small function, I reproduce its code here, with a size check
178 that causes failure if the size of msgbuf is exceeded. ****/
182 char *p = ((char*)responseptr) + IVAL(&responseptr->uUser.offset,0);
183 int len = SVAL(&responseptr->uUser.len,0)/2;
185 if (len + 1 >= sizeof(msgbuf)) return FAIL;
186 for (i = 0; i < len; ++i)
188 msgbuf[i] = *p & 0x7f;
194 /***************************************************************/
196 /* Put the username in $auth1 and $1. The former is now the preferred variable;
197 the latter is the original variable. */
199 auth_vars[0] = expand_nstring[1] = msgbuf;
200 expand_nlength[1] = Ustrlen(msgbuf);
203 debug_print_string(ablock->server_debug_string); /* customized debug */
205 /* look up password */
207 clearpass = expand_string(ob->spa_serverpassword);
208 if (clearpass == NULL)
210 if (expand_string_forcedfail)
212 DEBUG(D_auth) debug_printf("auth_spa_server(): forced failure while "
213 "expanding spa_serverpassword\n");
218 DEBUG(D_auth) debug_printf("auth_spa_server(): error while expanding "
219 "spa_serverpassword: %s\n", expand_string_message);
224 /* create local hash copy */
226 spa_smb_encrypt (clearpass, challenge.challengeData, lmRespData);
227 spa_smb_nt_encrypt (clearpass, challenge.challengeData, ntRespData);
229 /* compare NT hash (LM may not be available) */
231 if (memcmp(ntRespData,
232 ((unsigned char*)responseptr)+IVAL(&responseptr->ntResponse.offset,0),
234 /* success. we have a winner. */
236 /* Expand server_condition as an authorization check (PH) */
237 return auth_check_serv_cond(ablock);
243 /*************************************************
244 * Client entry point *
245 *************************************************/
247 /* For interface, see auths/README */
251 auth_instance *ablock, /* authenticator block */
252 smtp_inblock *inblock, /* connection inblock */
253 smtp_outblock *outblock, /* connection outblock */
254 int timeout, /* command timeout */
255 uschar *buffer, /* buffer for reading response */
256 int buffsize) /* size of buffer */
258 auth_spa_options_block *ob =
259 (auth_spa_options_block *)(ablock->options_block);
260 SPAAuthRequest request;
261 SPAAuthChallenge challenge;
262 SPAAuthResponse response;
265 char *username, *password;
267 /* Code added by PH to expand the options */
269 *buffer = 0; /* Default no message when cancelled */
271 username = CS expand_string(ob->spa_username);
272 if (username == NULL)
274 if (expand_string_forcedfail) return CANCELLED;
275 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
276 "authenticator: %s", ob->spa_username, ablock->name,
277 expand_string_message);
281 password = CS expand_string(ob->spa_password);
282 if (password == NULL)
284 if (expand_string_forcedfail) return CANCELLED;
285 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
286 "authenticator: %s", ob->spa_password, ablock->name,
287 expand_string_message);
291 if (ob->spa_domain != NULL)
293 domain = CS expand_string(ob->spa_domain);
296 if (expand_string_forcedfail) return CANCELLED;
297 string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
298 "authenticator: %s", ob->spa_domain, ablock->name,
299 expand_string_message);
306 if (smtp_write_command(outblock, FALSE, "AUTH %s\r\n",
307 ablock->public_name) < 0)
310 /* wait for the 3XX OK message */
311 if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
314 DSPA("\n\n%s authenticator: using domain %s\n\n",
315 ablock->name, domain);
317 spa_build_auth_request (&request, CS username, domain);
318 spa_bits_to_base64 (US msgbuf, (unsigned char*)&request,
319 spa_request_length(&request));
321 DSPA("\n\n%s authenticator: sending request (%s)\n\n", ablock->name,
324 /* send the encrypted password */
325 if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
328 /* wait for the auth challenge */
329 if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
332 /* convert the challenge into the challenge struct */
333 DSPA("\n\n%s authenticator: challenge (%s)\n\n",
334 ablock->name, buffer + 4);
335 spa_base64_to_bits ((char *)(&challenge), sizeof(challenge), (const char *)(buffer + 4));
337 spa_build_auth_response (&challenge, &response,
338 CS username, CS password);
339 spa_bits_to_base64 (US msgbuf, (unsigned char*)&response,
340 spa_request_length(&response));
341 DSPA("\n\n%s authenticator: challenge response (%s)\n\n", ablock->name,
344 /* send the challenge response */
345 if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
348 /* If we receive a success response from the server, authentication
349 has succeeded. There may be more data to send, but is there any point
350 in provoking an error here? */
351 if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout))
354 /* Not a success response. If errno != 0 there is some kind of transmission
355 error. Otherwise, check the response code in the buffer. If it starts with
356 '3', more data is expected. */
357 if (errno != 0 || buffer[0] != '3')