src/src/auths/cyrus_sasl.c

   1 /* $Cambridge: exim/src/src/auths/cyrus_sasl.c,v 1.3 2005/04/05 14:33:27 ph10 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) University of Cambridge 1995 - 2003 */
   8 /* See the file NOTICE for conditions of use and distribution. */
   9
  10 /* This code was originally contributed by Matthew Byng-Maddick */
  11
  12 /* Copyright (c) A L Digital 2004 */
  13
  14 /* A generic (mechanism independent) Cyrus SASL authenticator. */
  15
  16
  17 #include "../exim.h"
  18
  19
  20 /* We can't just compile this code and allow the library mechanism to omit the
  21 functions if they are not wanted, because we need to have the Cyrus SASL header
  22 available for compiling. Therefore, compile these functions only if
  23 AUTH_CYRUS_SASL is defined. However, some compilers don't like compiling empty
  24 modules, so keep them happy with a dummy when skipping the rest. Make it
  25 reference itself to stop picky compilers complaining that it is unused, and put
  26 in a dummy argument to stop even pickier compilers complaining about infinite
  27 loops. */
  28
  29 #ifndef AUTH_CYRUS_SASL
  30 static void dummy(int x) { dummy(x-1); }
  31 #else
  32
  33
  34 #include <sasl/sasl.h>
  35 #include "cyrus_sasl.h"
  36
  37 /* Options specific to the cyrus_sasl authentication mechanism. */
  38
  39 optionlist auth_cyrus_sasl_options[] = {
  40   { "server_hostname",      opt_stringptr,
  41       (void *)(offsetof(auth_cyrus_sasl_options_block, server_hostname)) },
  42   { "server_mech",          opt_stringptr,
  43       (void *)(offsetof(auth_cyrus_sasl_options_block, server_mech)) },
  44   { "server_realm",         opt_stringptr,
  45       (void *)(offsetof(auth_cyrus_sasl_options_block, server_realm)) },
  46   { "server_service",       opt_stringptr,
  47       (void *)(offsetof(auth_cyrus_sasl_options_block, server_service)) }
  48 };
  49
  50 /* Size of the options list. An extern variable has to be used so that its
  51 address can appear in the tables drtables.c. */
  52
  53 int auth_cyrus_sasl_options_count =
  54   sizeof(auth_cyrus_sasl_options)/sizeof(optionlist);
  55
  56 /* Default private options block for the contidion authentication method. */
  57
  58 auth_cyrus_sasl_options_block auth_cyrus_sasl_option_defaults = {
  59   US"smtp",         /* server_service */
  60   US"$primary_hostname", /* server_hostname */
  61   NULL,             /* server_realm */
  62   NULL              /* server_mech */
  63 };
  64
  65
  66 /*************************************************
  67 *          Initialization entry point            *
  68 *************************************************/
  69
  70 /* Called for each instance, after its options have been read, to
  71 enable consistency checks to be done, or anything else that needs
  72 to be set up. */
  73
  74
  75 /* Auxiliary function, passed in data to sasl_server_init(). */
  76
  77 static int
  78 mysasl_config(void *context,
  79               const char *plugin_name,
  80               const char *option,
  81               const char **result,
  82               unsigned int *len)
  83 {
  84 if (context && !strcmp(option, "mech_list"))
  85   {
  86   *result = context;
  87   if (len != NULL) *len = strlen(*result);
  88   return SASL_OK;
  89   }
  90 return SASL_FAIL;
  91 }
  92
  93 /* Here's the real function */
  94
  95 void
  96 auth_cyrus_sasl_init(auth_instance *ablock)
  97 {
  98 auth_cyrus_sasl_options_block *ob =
  99   (auth_cyrus_sasl_options_block *)(ablock->options_block);
 100 uschar *list, *listptr, *buffer;
 101 int rc, i;
 102 unsigned int len;
 103 uschar *rs_point;
 104
 105 sasl_conn_t *conn;
 106 sasl_callback_t cbs[]={
 107   {SASL_CB_GETOPT, NULL, NULL },
 108   {SASL_CB_LIST_END, NULL, NULL}};
 109
 110 /* default the mechanism to our "public name" */
 111 if(ob->server_mech == NULL)
 112   ob->server_mech=string_copy(ablock->public_name);
 113
 114 /* we're going to initialise the library to check that there is an
 115  * authenticator of type whatever mechanism we're using
 116  */
 117
 118 cbs[0].proc = &mysasl_config;
 119 cbs[0].context = ob->server_mech;
 120
 121 rc=sasl_server_init(cbs, "exim");
 122
 123 if( rc != SASL_OK )
 124   log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
 125       "couldn't initialise Cyrus SASL library.", ablock->name);
 126
 127 rc=sasl_server_new(CS ob->server_service, CS primary_hostname,
 128                    CS ob->server_realm, NULL, NULL, NULL, 0, &conn);
 129 if( rc != SASL_OK )
 130   log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
 131       "couldn't initialise Cyrus SASL server connection.", ablock->name);
 132
 133 rc=sasl_listmech(conn, NULL, "", ":", "", (const char **)(&list), &len, &i);
 134 if( rc != SASL_OK )
 135   log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
 136       "couldn't get Cyrus SASL mechanism list.", ablock->name);
 137
 138 i=':';
 139 listptr=list;
 140
 141 HDEBUG(D_auth) debug_printf("Cyrus SASL knows about: %s\n", list);
 142
 143 /* the store_get / store_reset mechanism is hierarchical
 144  * the hierarchy is stored for us behind our back. This point
 145  * creates a hierarchy point for this function.
 146  */
 147 rs_point=store_get(0);
 148
 149 /* loop until either we get to the end of the list, or we match the
 150  * public name of this authenticator
 151  */
 152 while( ( buffer = string_nextinlist(&listptr, &i, NULL, 0) ) &&
 153        strcmpic(buffer,ob->server_mech) );
 154
 155 if(!buffer)
 156   log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
 157       "Cyrus SASL doesn't know about mechanism %s.", ablock->name, ob->server_mech);
 158
 159 store_reset(rs_point);
 160
 161 HDEBUG(D_auth) debug_printf("Cyrus SASL driver %s: %s initialised\n", ablock->name, ablock->public_name);
 162
 163 /* make sure that if we get here then we're allowed to advertise. */
 164 ablock->server = TRUE;
 165
 166 sasl_dispose(&conn);
 167 sasl_done();
 168 }
 169
 170 /*************************************************
 171 *             Server entry point                 *
 172 *************************************************/
 173
 174 /* For interface, see auths/README */
 175
 176 /* note, we don't care too much about memory allocation in this, because this is entirely
 177  * within a shortlived child
 178  */
 179
 180 int
 181 auth_cyrus_sasl_server(auth_instance *ablock, uschar *data)
 182 {
 183 auth_cyrus_sasl_options_block *ob =
 184   (auth_cyrus_sasl_options_block *)(ablock->options_block);
 185 uschar *output, *out2, *input, *clear, *hname;
 186 uschar *debug = NULL;   /* Stops compiler complaining */
 187 sasl_callback_t cbs[]={{SASL_CB_LIST_END, NULL, NULL}};
 188 sasl_conn_t *conn;
 189 int rc, firsttime=1, clen;
 190 unsigned int inlen, outlen;
 191
 192 input=data;
 193 inlen=Ustrlen(data);
 194
 195 HDEBUG(D_auth) debug=string_copy(data);
 196
 197 hname=expand_string(ob->server_hostname);
 198 if(hname == NULL)
 199   {
 200   auth_defer_msg = expand_string_message;
 201   return DEFER;
 202   }
 203
 204 if(inlen)
 205   {
 206   clen=auth_b64decode(input, &clear);
 207   if(clen < 0)
 208     {
 209     return BAD64;
 210     }
 211   input=clear;
 212   inlen=clen;
 213   }
 214
 215 rc=sasl_server_init(cbs, "exim");
 216 if (rc != SASL_OK)
 217   {
 218   auth_defer_msg = US"couldn't initialise Cyrus SASL library";
 219   return DEFER;
 220   }
 221
 222 rc=sasl_server_new(CS ob->server_service, CS hname, CS ob->server_realm, NULL,
 223   NULL, NULL, 0, &conn);
 224
 225 if( rc != SASL_OK )
 226   {
 227   auth_defer_msg = US"couldn't initialise Cyrus SASL connection";
 228   sasl_done();
 229   return DEFER;
 230   }
 231
 232 rc=SASL_CONTINUE;
 233
 234 while(rc==SASL_CONTINUE)
 235   {
 236   if(firsttime)
 237     {
 238     firsttime=0;
 239     HDEBUG(D_auth) debug_printf("Calling sasl_server_start(%s,\"%s\")\n", ob->server_mech, debug);
 240     rc=sasl_server_start(conn, CS ob->server_mech, inlen?CS input:NULL, inlen,
 241            (const char **)(&output), &outlen);
 242     }
 243   else
 244     {
 245     /* make sure that we have a null-terminated string */
 246     out2=store_get(outlen+1);
 247     memcpy(out2,output,outlen);
 248     out2[outlen]='\0';
 249     if((rc=auth_get_data(&input, out2, outlen))!=OK)
 250       {
 251       /* we couldn't get the data, so free up the library before
 252        * returning whatever error we get */
 253       sasl_dispose(&conn);
 254       sasl_done();
 255       return rc;
 256       }
 257     inlen=Ustrlen(input);
 258
 259     HDEBUG(D_auth) debug=string_copy(input);
 260     if(inlen)
 261       {
 262       clen=auth_b64decode(input, &clear);
 263       if(clen < 0)
 264        {
 265         sasl_dispose(&conn);
 266         sasl_done();
 267        return BAD64;
 268        }
 269       input=clear;
 270       inlen=clen;
 271       }
 272
 273     HDEBUG(D_auth) debug_printf("Calling sasl_server_step(\"%s\")\n", debug);
 274     rc=sasl_server_step(conn, CS input, inlen, (const char **)(&output), &outlen);
 275     }
 276   if(rc==SASL_BADPROT)
 277     {
 278     sasl_dispose(&conn);
 279     sasl_done();
 280     return UNEXPECTED;
 281     }
 282   else if( rc==SASL_FAIL     || rc==SASL_BUFOVER
 283        || rc==SASL_BADMAC   || rc==SASL_BADAUTH
 284        || rc==SASL_NOAUTHZ  || rc==SASL_ENCRYPT
 285        || rc==SASL_EXPIRED  || rc==SASL_DISABLED
 286        || rc==SASL_NOUSER   )
 287     {
 288     /* these are considered permanent failure codes */
 289     HDEBUG(D_auth)
 290       debug_printf("Cyrus SASL permanent failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
 291     log_write(0, LOG_REJECT, "%s authenticator (%s):\n  "
 292        "Cyrus SASL permanent failure: %s", ablock->name, ob->server_mech,
 293        sasl_errstring(rc, NULL, NULL));
 294     sasl_dispose(&conn);
 295     sasl_done();
 296     return FAIL;
 297     }
 298   else if(rc==SASL_NOMECH)
 299     {
 300     /* this is a temporary failure, because the mechanism is not
 301      * available for this user. If it wasn't available at all, we
 302      * shouldn't have got here in the first place...
 303      */
 304     HDEBUG(D_auth)
 305       debug_printf("Cyrus SASL temporary failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
 306     auth_defer_msg =
 307         string_sprintf("Cyrus SASL: mechanism %s not available", ob->server_mech);
 308     sasl_dispose(&conn);
 309     sasl_done();
 310     return DEFER;
 311     }
 312   else if(!(rc==SASL_OK || rc==SASL_CONTINUE))
 313     {
 314     /* Anything else is a temporary failure, and we'll let SASL print out
 315      * the error string for us
 316      */
 317     HDEBUG(D_auth)
 318       debug_printf("Cyrus SASL temporary failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
 319     auth_defer_msg =
 320         string_sprintf("Cyrus SASL: %s", sasl_errstring(rc, NULL, NULL));
 321     sasl_dispose(&conn);
 322     sasl_done();
 323     return DEFER;
 324     }
 325   else if(rc==SASL_OK)
 326     {
 327     /* get the username and copy it into $1 */
 328     rc=sasl_getprop(conn, SASL_USERNAME, (const void **)(&out2));
 329     expand_nstring[1]=string_copy(out2);
 330     expand_nlength[1]=Ustrlen(expand_nstring[1]);
 331     expand_nmax=1;
 332
 333     HDEBUG(D_auth)
 334       debug_printf("Cyrus SASL %s authentiction succeeded for %s\n", ob->server_mech, out2);
 335     /* close down the connection, freeing up library's memory */
 336     sasl_dispose(&conn);
 337     sasl_done();
 338     return OK;
 339     }
 340   }
 341 /* NOTREACHED */
 342 return 0;  /* Stop compiler complaints */
 343 }
 344
 345 /*************************************************
 346 *              Client entry point                *
 347 *************************************************/
 348
 349 /* For interface, see auths/README */
 350
 351 int
 352 auth_cyrus_sasl_client(
 353   auth_instance *ablock,                 /* authenticator block */
 354   smtp_inblock *inblock,                 /* input connection */
 355   smtp_outblock *outblock,               /* output connection */
 356   int timeout,                           /* command timeout */
 357   uschar *buffer,                          /* for reading response */
 358   int buffsize)                          /* size of buffer */
 359 {
 360 /* We don't support clients (yet) in this implementation of cyrus_sasl */
 361 return FAIL;
 362 }
 363
 364 #endif  /* AUTH_CYRUS_SASL */
 365
 366 /* End of cyrus_sasl.c */