src/src/auths/dovecot.c

   1 /* $Cambridge: exim/src/src/auths/dovecot.c,v 1.10 2008/05/16 12:22:08 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     }
 135
 136   while (p < sbp)
 137     {
 138     if (count >= n - 1) break;
 139     s[count++] = sbuffer[p];
 140     if (sbuffer[p++] == '\n') break;
 141     }
 142
 143   memmove(sbuffer, sbuffer + p, sbp - p);
 144   sbp -= p;
 145
 146   if (s[count-1] == '\n' || count >= n - 1) break;
 147   }
 148
 149 s[count] = 0;
 150 return s;
 151 }
 152
 153
 154
 155
 156 /*************************************************
 157 *              Server entry point                *
 158 *************************************************/
 159
 160 int auth_dovecot_server(auth_instance *ablock, uschar *data)
 161 {
 162        auth_dovecot_options_block *ob =
 163                (auth_dovecot_options_block *)(ablock->options_block);
 164        struct sockaddr_un sa;
 165        uschar buffer[4096];
 166        uschar *args[8];
 167        uschar *auth_command;
 168        uschar *auth_extra_data = US"";
 169        int nargs, tmp;
 170        int cuid = 0, cont = 1, found = 0, fd, ret = DEFER;
 171
 172        HDEBUG(D_auth) debug_printf("dovecot authentication\n");
 173
 174        memset(&sa, 0, sizeof(sa));
 175        sa.sun_family = AF_UNIX;
 176
 177        /* This was the original code here: it is nonsense because strncpy()
 178        does not return an integer. I have converted this to use the function
 179        that formats and checks length. PH */
 180
 181        /*
 182        if (strncpy(sa.sun_path, ob->server_socket, sizeof(sa.sun_path)) < 0) {
 183        */
 184
 185        if (!string_format(US sa.sun_path, sizeof(sa.sun_path), "%s",
 186                           ob->server_socket)) {
 187                auth_defer_msg = US"authentication socket path too long";
 188                return DEFER;
 189        }
 190
 191        auth_defer_msg = US"authentication socket connection error";
 192
 193        fd = socket(PF_UNIX, SOCK_STREAM, 0);
 194        if (fd < 0)
 195                return DEFER;
 196
 197        if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
 198                goto out;
 199
 200        auth_defer_msg = US"authentication socket protocol error";
 201
 202        sbp = 0;  /* Socket buffer pointer */
 203        while (cont) {
 204                if (dc_gets(buffer, sizeof(buffer), fd) == NULL)
 205                        OUT("authentication socket read error or premature eof");
 206
 207                buffer[Ustrlen(buffer) - 1] = 0;
 208                HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
 209                nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
 210
 211                switch (toupper(*args[0])) {
 212                case 'C':
 213                        CHECK_COMMAND("CUID", 1, 1);
 214                        cuid = Uatoi(args[1]);
 215                        break;
 216
 217                case 'D':
 218                        CHECK_COMMAND("DONE", 0, 0);
 219                        cont = 0;
 220                        break;
 221
 222                case 'M':
 223                        CHECK_COMMAND("MECH", 1, INT_MAX);
 224                        if (strcmpic(US args[1], ablock->public_name) == 0)
 225                                found = 1;
 226                        break;
 227
 228                case 'S':
 229                        CHECK_COMMAND("SPID", 1, 1);
 230                        break;
 231
 232                case 'V':
 233                        CHECK_COMMAND("VERSION", 2, 2);
 234                        if (Uatoi(args[1]) != VERSION_MAJOR)
 235                                OUT("authentication socket protocol version mismatch");
 236                        break;
 237
 238                default:
 239                        goto out;
 240                }
 241        }
 242
 243        if (!found)
 244                goto out;
 245
 246        /* Added by PH: data must not contain tab (as it is
 247        b64 it shouldn't, but check for safety). */
 248
 249        if (Ustrchr(data, '\t') != NULL) {
 250                ret = FAIL;
 251                goto out;
 252        }
 253
 254        /* Added by PH: extra fields when TLS is in use or if the TCP/IP
 255        connection is local. */
 256
 257        if (tls_cipher != NULL)
 258                auth_extra_data = string_sprintf("secured\t%s%s",
 259                    tls_certificate_verified? "valid-client-cert" : "",
 260                    tls_certificate_verified? "\t" : "");
 261        else if (interface_address != NULL &&
 262                 Ustrcmp(sender_host_address, interface_address) == 0)
 263                auth_extra_data = US"secured\t";
 264
 265
 266 /****************************************************************************
 267    The code below was the original code here. It didn't work. A reading of the
 268    file auth-protocol.txt.gz that came with Dovecot 1.0_beta8 indicated that
 269    this was not right. Maybe something changed. I changed it to move the
 270    service indication into the AUTH command, and it seems to be better. PH
 271
 272        fprintf(f, "VERSION\t%d\t%d\r\nSERVICE\tSMTP\r\nCPID\t%d\r\n"
 273                "AUTH\t%d\t%s\trip=%s\tlip=%s\tresp=%s\r\n",
 274                VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
 275                ablock->public_name, sender_host_address, interface_address,
 276                data ? (char *) data : "");
 277
 278    Subsequently, the command was modified to add "secured" and "valid-client-
 279    cert" when relevant.
 280
 281    The auth protocol is documented here:
 282         http://wiki.dovecot.org/Authentication_Protocol
 283 ****************************************************************************/
 284
 285        auth_command = string_sprintf("VERSION\t%d\t%d\nCPID\t%d\n"
 286                "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tnologin\tresp=%s\n",
 287                VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
 288                ablock->public_name, auth_extra_data, sender_host_address,
 289                interface_address, data ? (char *) data : "");
 290
 291        if (write(fd, auth_command, Ustrlen(auth_command)) < 0)
 292               HDEBUG(D_auth) debug_printf("error sending auth_command: %s\n",
 293                 strerror(errno));
 294
 295        HDEBUG(D_auth) debug_printf("sent: %s", auth_command);
 296
 297        while (1) {
 298                uschar *temp;
 299                uschar *auth_id_pre = NULL;
 300                int i;
 301
 302                if (dc_gets(buffer, sizeof(buffer), fd) == NULL) {
 303                        auth_defer_msg = US"authentication socket read error or premature eof";
 304                        goto out;
 305                }
 306
 307                buffer[Ustrlen(buffer) - 1] = 0;
 308                HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
 309                nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
 310
 311                if (Uatoi(args[1]) != cuid)
 312                        OUT("authentication socket connection id mismatch");
 313
 314                switch (toupper(*args[0])) {
 315                case 'C':
 316                        CHECK_COMMAND("CONT", 1, 2);
 317
 318                        tmp = auth_get_no64_data(&data, US args[2]);
 319                        if (tmp != OK) {
 320                                ret = tmp;
 321                                goto out;
 322                        }
 323
 324                        /* Added by PH: data must not contain tab (as it is
 325                        b64 it shouldn't, but check for safety). */
 326
 327                        if (Ustrchr(data, '\t') != NULL) {
 328                                ret = FAIL;
 329                                goto out;
 330                        }
 331
 332                        temp = string_sprintf("CONT\t%d\t%s\n", cuid, data);
 333                        if (write(fd, temp, Ustrlen(temp)) < 0)
 334                                OUT("authentication socket write error");
 335                        break;
 336
 337                case 'F':
 338                        CHECK_COMMAND("FAIL", 1, -1);
 339
 340                        for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
 341                        {
 342                                if ( Ustrncmp(args[i], US"user=", 5) == 0 )
 343                                {
 344                                        auth_id_pre = args[i]+5;
 345                                        expand_nstring[1] = auth_vars[0] =
 346                                                string_copy(auth_id_pre); /* PH */
 347                                        expand_nlength[1] = Ustrlen(auth_id_pre);
 348                                        expand_nmax = 1;
 349                                }
 350                        }
 351
 352                        ret = FAIL;
 353                        goto out;
 354
 355                case 'O':
 356                        CHECK_COMMAND("OK", 2, -1);
 357
 358                        /*
 359                         * Search for the "user=$USER" string in the args array
 360                         * and return the proper value.
 361                         */
 362                        for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
 363                        {
 364                                if ( Ustrncmp(args[i], US"user=", 5) == 0 )
 365                                {
 366                                        auth_id_pre = args[i]+5;
 367                                        expand_nstring[1] = auth_vars[0] =
 368                                                string_copy(auth_id_pre); /* PH */
 369                                        expand_nlength[1] = Ustrlen(auth_id_pre);
 370                                        expand_nmax = 1;
 371                                }
 372                        }
 373
 374                        if (auth_id_pre == NULL)
 375                                OUT("authentication socket protocol error, username missing");
 376
 377                        ret = OK;
 378                        /* fallthrough */
 379
 380                default:
 381                        goto out;
 382                }
 383        }
 384
 385 out:
 386        /* close the socket used by dovecot */
 387        if (fd >= 0)
 388               close(fd);
 389
 390        /* Expand server_condition as an authorization check */
 391        return (ret == OK)? auth_check_serv_cond(ablock) : ret;
 392 }