src/src/auths/dovecot.c

   1 /* $Cambridge: exim/src/src/auths/dovecot.c,v 1.11 2009/10/26 13:18:54 nm4 Exp $ */
   2
   3 /*
   4  * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published
   8  * by the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 /* A number of modifications have been made to the original code. Originally I
  13 commented them specially, but now they are getting quite extensive, so I have
  14 ceased doing that. The biggest change is to use unbuffered I/O on the socket
  15 because using C buffered I/O gives problems on some operating systems. PH */
  16
  17 #include "../exim.h"
  18 #include "dovecot.h"
  19
  20 #define VERSION_MAJOR  1
  21 #define VERSION_MINOR  0
  22
  23 /* Options specific to the authentication mechanism. */
  24 optionlist auth_dovecot_options[] = {
  25        {
  26        "server_socket",
  27        opt_stringptr,
  28        (void *)(offsetof(auth_dovecot_options_block, server_socket))
  29        },
  30 };
  31
  32 /* Size of the options list. An extern variable has to be used so that its
  33 address can appear in the tables drtables.c. */
  34
  35 int auth_dovecot_options_count =
  36        sizeof(auth_dovecot_options) / sizeof(optionlist);
  37
  38 /* Default private options block for the authentication method. */
  39
  40 auth_dovecot_options_block auth_dovecot_option_defaults = {
  41        NULL,                           /* server_socket */
  42 };
  43
  44
  45 /* Static variables for reading from the socket */
  46
  47 static uschar sbuffer[256];
  48 static int sbp;
  49
  50
  51
  52 /*************************************************
  53  *          Initialization entry point           *
  54  *************************************************/
  55
  56 /* Called for each instance, after its options have been read, to
  57 enable consistency checks to be done, or anything else that needs
  58 to be set up. */
  59
  60 void auth_dovecot_init(auth_instance *ablock)
  61 {
  62        auth_dovecot_options_block *ob =
  63                (auth_dovecot_options_block *)(ablock->options_block);
  64
  65        if (ablock->public_name == NULL)
  66                ablock->public_name = ablock->name;
  67        if (ob->server_socket != NULL)
  68                ablock->server = TRUE;
  69        ablock->client = FALSE;
  70 }
  71
  72 static int strcut(uschar *str, uschar **ptrs, int nptrs)
  73 {
  74        uschar *tmp = str;
  75        int n;
  76
  77        for (n = 0; n < nptrs; n++)
  78                ptrs[n] = NULL;
  79        n = 1;
  80
  81        while (*str) {
  82                if (*str == '\t') {
  83                        if (n <= nptrs) {
  84                                *ptrs++ = tmp;
  85                                tmp = str + 1;
  86                                *str = 0;
  87                        }
  88                        n++;
  89                }
  90                str++;
  91        }
  92
  93        if (n < nptrs)
  94                *ptrs = tmp;
  95
  96        return n;
  97 }
  98
  99 #define CHECK_COMMAND(str, arg_min, arg_max) do { \
 100        if (strcmpic(US(str), args[0]) != 0) \
 101                goto out; \
 102        if (nargs - 1 < (arg_min)) \
 103                goto out; \
 104        if ( (arg_max != -1) && (nargs - 1 > (arg_max)) ) \
 105                goto out; \
 106 } while (0)
 107
 108 #define OUT(msg) do { \
 109        auth_defer_msg = (US msg); \
 110        goto out; \
 111 } while(0)
 112
 113
 114
 115 /*************************************************
 116 *      "fgets" to read directly from socket      *
 117 *************************************************/
 118
 119 /* Added by PH after a suggestion by Steve Usher because the previous use of
 120 C-style buffered I/O gave trouble. */
 121
 122 static uschar *
 123 dc_gets(uschar *s, int n, int fd)
 124 {
 125 int p = 0;
 126 int count = 0;
 127
 128 for (;;)
 129   {
 130   if (sbp == 0)
 131     {
 132     sbp = read(fd, sbuffer, sizeof(sbuffer));
 133     if (sbp == 0) { if (count == 0) return NULL; else break; }
 134     p = 0;
 135     }
 136
 137   while (p < sbp)
 138     {
 139     if (count >= n - 1) break;
 140     s[count++] = sbuffer[p];
 141     if (sbuffer[p++] == '\n') break;
 142     }
 143
 144   memmove(sbuffer, sbuffer + p, sbp - p);
 145   sbp -= p;
 146
 147   if (s[count-1] == '\n' || count >= n - 1) break;
 148   }
 149
 150 s[count] = 0;
 151 return s;
 152 }
 153
 154
 155
 156
 157 /*************************************************
 158 *              Server entry point                *
 159 *************************************************/
 160
 161 int auth_dovecot_server(auth_instance *ablock, uschar *data)
 162 {
 163        auth_dovecot_options_block *ob =
 164                (auth_dovecot_options_block *)(ablock->options_block);
 165        struct sockaddr_un sa;
 166        uschar buffer[4096];
 167        uschar *args[8];
 168        uschar *auth_command;
 169        uschar *auth_extra_data = US"";
 170        int nargs, tmp;
 171        int cuid = 0, cont = 1, found = 0, fd, ret = DEFER;
 172
 173        HDEBUG(D_auth) debug_printf("dovecot authentication\n");
 174
 175        memset(&sa, 0, sizeof(sa));
 176        sa.sun_family = AF_UNIX;
 177
 178        /* This was the original code here: it is nonsense because strncpy()
 179        does not return an integer. I have converted this to use the function
 180        that formats and checks length. PH */
 181
 182        /*
 183        if (strncpy(sa.sun_path, ob->server_socket, sizeof(sa.sun_path)) < 0) {
 184        */
 185
 186        if (!string_format(US sa.sun_path, sizeof(sa.sun_path), "%s",
 187                           ob->server_socket)) {
 188                auth_defer_msg = US"authentication socket path too long";
 189                return DEFER;
 190        }
 191
 192        auth_defer_msg = US"authentication socket connection error";
 193
 194        fd = socket(PF_UNIX, SOCK_STREAM, 0);
 195        if (fd < 0)
 196                return DEFER;
 197
 198        if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
 199                goto out;
 200
 201        auth_defer_msg = US"authentication socket protocol error";
 202
 203        sbp = 0;  /* Socket buffer pointer */
 204        while (cont) {
 205                if (dc_gets(buffer, sizeof(buffer), fd) == NULL)
 206                        OUT("authentication socket read error or premature eof");
 207
 208                buffer[Ustrlen(buffer) - 1] = 0;
 209                HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
 210                nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
 211
 212                switch (toupper(*args[0])) {
 213                case 'C':
 214                        CHECK_COMMAND("CUID", 1, 1);
 215                        cuid = Uatoi(args[1]);
 216                        break;
 217
 218                case 'D':
 219                        CHECK_COMMAND("DONE", 0, 0);
 220                        cont = 0;
 221                        break;
 222
 223                case 'M':
 224                        CHECK_COMMAND("MECH", 1, INT_MAX);
 225                        if (strcmpic(US args[1], ablock->public_name) == 0)
 226                                found = 1;
 227                        break;
 228
 229                case 'S':
 230                        CHECK_COMMAND("SPID", 1, 1);
 231                        break;
 232
 233                case 'V':
 234                        CHECK_COMMAND("VERSION", 2, 2);
 235                        if (Uatoi(args[1]) != VERSION_MAJOR)
 236                                OUT("authentication socket protocol version mismatch");
 237                        break;
 238
 239                default:
 240                        goto out;
 241                }
 242        }
 243
 244        if (!found)
 245                goto out;
 246
 247        /* Added by PH: data must not contain tab (as it is
 248        b64 it shouldn't, but check for safety). */
 249
 250        if (Ustrchr(data, '\t') != NULL) {
 251                ret = FAIL;
 252                goto out;
 253        }
 254
 255        /* Added by PH: extra fields when TLS is in use or if the TCP/IP
 256        connection is local. */
 257
 258        if (tls_cipher != NULL)
 259                auth_extra_data = string_sprintf("secured\t%s%s",
 260                    tls_certificate_verified? "valid-client-cert" : "",
 261                    tls_certificate_verified? "\t" : "");
 262        else if (interface_address != NULL &&
 263                 Ustrcmp(sender_host_address, interface_address) == 0)
 264                auth_extra_data = US"secured\t";
 265
 266
 267 /****************************************************************************
 268    The code below was the original code here. It didn't work. A reading of the
 269    file auth-protocol.txt.gz that came with Dovecot 1.0_beta8 indicated that
 270    this was not right. Maybe something changed. I changed it to move the
 271    service indication into the AUTH command, and it seems to be better. PH
 272
 273        fprintf(f, "VERSION\t%d\t%d\r\nSERVICE\tSMTP\r\nCPID\t%d\r\n"
 274                "AUTH\t%d\t%s\trip=%s\tlip=%s\tresp=%s\r\n",
 275                VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
 276                ablock->public_name, sender_host_address, interface_address,
 277                data ? (char *) data : "");
 278
 279    Subsequently, the command was modified to add "secured" and "valid-client-
 280    cert" when relevant.
 281
 282    The auth protocol is documented here:
 283         http://wiki.dovecot.org/Authentication_Protocol
 284 ****************************************************************************/
 285
 286        auth_command = string_sprintf("VERSION\t%d\t%d\nCPID\t%d\n"
 287                "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tnologin\tresp=%s\n",
 288                VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
 289                ablock->public_name, auth_extra_data, sender_host_address,
 290                interface_address, data ? (char *) data : "");
 291
 292        if (write(fd, auth_command, Ustrlen(auth_command)) < 0)
 293               HDEBUG(D_auth) debug_printf("error sending auth_command: %s\n",
 294                 strerror(errno));
 295
 296        HDEBUG(D_auth) debug_printf("sent: %s", auth_command);
 297
 298        while (1) {
 299                uschar *temp;
 300                uschar *auth_id_pre = NULL;
 301                int i;
 302
 303                if (dc_gets(buffer, sizeof(buffer), fd) == NULL) {
 304                        auth_defer_msg = US"authentication socket read error or premature eof";
 305                        goto out;
 306                }
 307
 308                buffer[Ustrlen(buffer) - 1] = 0;
 309                HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
 310                nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
 311
 312                if (Uatoi(args[1]) != cuid)
 313                        OUT("authentication socket connection id mismatch");
 314
 315                switch (toupper(*args[0])) {
 316                case 'C':
 317                        CHECK_COMMAND("CONT", 1, 2);
 318
 319                        tmp = auth_get_no64_data(&data, US args[2]);
 320                        if (tmp != OK) {
 321                                ret = tmp;
 322                                goto out;
 323                        }
 324
 325                        /* Added by PH: data must not contain tab (as it is
 326                        b64 it shouldn't, but check for safety). */
 327
 328                        if (Ustrchr(data, '\t') != NULL) {
 329                                ret = FAIL;
 330                                goto out;
 331                        }
 332
 333                        temp = string_sprintf("CONT\t%d\t%s\n", cuid, data);
 334                        if (write(fd, temp, Ustrlen(temp)) < 0)
 335                                OUT("authentication socket write error");
 336                        break;
 337
 338                case 'F':
 339                        CHECK_COMMAND("FAIL", 1, -1);
 340
 341                        for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
 342                        {
 343                                if ( Ustrncmp(args[i], US"user=", 5) == 0 )
 344                                {
 345                                        auth_id_pre = args[i]+5;
 346                                        expand_nstring[1] = auth_vars[0] =
 347                                                string_copy(auth_id_pre); /* PH */
 348                                        expand_nlength[1] = Ustrlen(auth_id_pre);
 349                                        expand_nmax = 1;
 350                                }
 351                        }
 352
 353                        ret = FAIL;
 354                        goto out;
 355
 356                case 'O':
 357                        CHECK_COMMAND("OK", 2, -1);
 358
 359                        /*
 360                         * Search for the "user=$USER" string in the args array
 361                         * and return the proper value.
 362                         */
 363                        for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
 364                        {
 365                                if ( Ustrncmp(args[i], US"user=", 5) == 0 )
 366                                {
 367                                        auth_id_pre = args[i]+5;
 368                                        expand_nstring[1] = auth_vars[0] =
 369                                                string_copy(auth_id_pre); /* PH */
 370                                        expand_nlength[1] = Ustrlen(auth_id_pre);
 371                                        expand_nmax = 1;
 372                                }
 373                        }
 374
 375                        if (auth_id_pre == NULL)
 376                                OUT("authentication socket protocol error, username missing");
 377
 378                        ret = OK;
 379                        /* fallthrough */
 380
 381                default:
 382                        goto out;
 383                }
 384        }
 385
 386 out:
 387        /* close the socket used by dovecot */
 388        if (fd >= 0)
 389               close(fd);
 390
 391        /* Expand server_condition as an authorization check */
 392        return (ret == OK)? auth_check_serv_cond(ablock) : ret;
 393 }