src/src/auths/dovecot.c

   1 /*
   2  * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published
   6  * by the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  */
   9
  10 /* A number of modifications have been made to the original code. Originally I
  11 commented them specially, but now they are getting quite extensive, so I have
  12 ceased doing that. The biggest change is to use unbuffered I/O on the socket
  13 because using C buffered I/O gives problems on some operating systems. PH */
  14
  15 #include "../exim.h"
  16 #include "dovecot.h"
  17
  18 #define VERSION_MAJOR  1
  19 #define VERSION_MINOR  0
  20
  21 /* Options specific to the authentication mechanism. */
  22 optionlist auth_dovecot_options[] = {
  23        {
  24        "server_socket",
  25        opt_stringptr,
  26        (void *)(offsetof(auth_dovecot_options_block, server_socket))
  27        },
  28 };
  29
  30 /* Size of the options list. An extern variable has to be used so that its
  31 address can appear in the tables drtables.c. */
  32
  33 int auth_dovecot_options_count =
  34        sizeof(auth_dovecot_options) / sizeof(optionlist);
  35
  36 /* Default private options block for the authentication method. */
  37
  38 auth_dovecot_options_block auth_dovecot_option_defaults = {
  39        NULL,                           /* server_socket */
  40 };
  41
  42
  43 /* Static variables for reading from the socket */
  44
  45 static uschar sbuffer[256];
  46 static int sbp;
  47
  48
  49
  50 /*************************************************
  51  *          Initialization entry point           *
  52  *************************************************/
  53
  54 /* Called for each instance, after its options have been read, to
  55 enable consistency checks to be done, or anything else that needs
  56 to be set up. */
  57
  58 void auth_dovecot_init(auth_instance *ablock)
  59 {
  60        auth_dovecot_options_block *ob =
  61                (auth_dovecot_options_block *)(ablock->options_block);
  62
  63        if (ablock->public_name == NULL)
  64                ablock->public_name = ablock->name;
  65        if (ob->server_socket != NULL)
  66                ablock->server = TRUE;
  67        ablock->client = FALSE;
  68 }
  69
  70 static int strcut(uschar *str, uschar **ptrs, int nptrs)
  71 {
  72        uschar *tmp = str;
  73        int n;
  74
  75        for (n = 0; n < nptrs; n++)
  76                ptrs[n] = NULL;
  77        n = 1;
  78
  79        while (*str) {
  80                if (*str == '\t') {
  81                        if (n <= nptrs) {
  82                                *ptrs++ = tmp;
  83                                tmp = str + 1;
  84                                *str = 0;
  85                        }
  86                        n++;
  87                }
  88                str++;
  89        }
  90
  91        if (n < nptrs)
  92                *ptrs = tmp;
  93
  94        return n;
  95 }
  96
  97 #define CHECK_COMMAND(str, arg_min, arg_max) do { \
  98        if (strcmpic(US(str), args[0]) != 0) \
  99                goto out; \
 100        if (nargs - 1 < (arg_min)) \
 101                goto out; \
 102        if ( (arg_max != -1) && (nargs - 1 > (arg_max)) ) \
 103                goto out; \
 104 } while (0)
 105
 106 #define OUT(msg) do { \
 107        auth_defer_msg = (US msg); \
 108        goto out; \
 109 } while(0)
 110
 111
 112
 113 /*************************************************
 114 *      "fgets" to read directly from socket      *
 115 *************************************************/
 116
 117 /* Added by PH after a suggestion by Steve Usher because the previous use of
 118 C-style buffered I/O gave trouble. */
 119
 120 static uschar *
 121 dc_gets(uschar *s, int n, int fd)
 122 {
 123 int p = 0;
 124 int count = 0;
 125
 126 for (;;)
 127   {
 128   if (sbp == 0)
 129     {
 130     sbp = read(fd, sbuffer, sizeof(sbuffer));
 131     if (sbp == 0) { if (count == 0) return NULL; else break; }
 132     p = 0;
 133     }
 134
 135   while (p < sbp)
 136     {
 137     if (count >= n - 1) break;
 138     s[count++] = sbuffer[p];
 139     if (sbuffer[p++] == '\n') break;
 140     }
 141
 142   memmove(sbuffer, sbuffer + p, sbp - p);
 143   sbp -= p;
 144
 145   if (s[count-1] == '\n' || count >= n - 1) break;
 146   }
 147
 148 s[count] = 0;
 149 return s;
 150 }
 151
 152
 153
 154
 155 /*************************************************
 156 *              Server entry point                *
 157 *************************************************/
 158
 159 int auth_dovecot_server(auth_instance *ablock, uschar *data)
 160 {
 161        auth_dovecot_options_block *ob =
 162                (auth_dovecot_options_block *)(ablock->options_block);
 163        struct sockaddr_un sa;
 164        uschar buffer[4096];
 165        uschar *args[8];
 166        uschar *auth_command;
 167        uschar *auth_extra_data = US"";
 168        int nargs, tmp;
 169        int cuid = 0, cont = 1, found = 0, fd, ret = DEFER;
 170
 171        HDEBUG(D_auth) debug_printf("dovecot authentication\n");
 172
 173        memset(&sa, 0, sizeof(sa));
 174        sa.sun_family = AF_UNIX;
 175
 176        /* This was the original code here: it is nonsense because strncpy()
 177        does not return an integer. I have converted this to use the function
 178        that formats and checks length. PH */
 179
 180        /*
 181        if (strncpy(sa.sun_path, ob->server_socket, sizeof(sa.sun_path)) < 0) {
 182        */
 183
 184        if (!string_format(US sa.sun_path, sizeof(sa.sun_path), "%s",
 185                           ob->server_socket)) {
 186                auth_defer_msg = US"authentication socket path too long";
 187                return DEFER;
 188        }
 189
 190        auth_defer_msg = US"authentication socket connection error";
 191
 192        fd = socket(PF_UNIX, SOCK_STREAM, 0);
 193        if (fd < 0)
 194                return DEFER;
 195
 196        if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
 197                goto out;
 198
 199        auth_defer_msg = US"authentication socket protocol error";
 200
 201        sbp = 0;  /* Socket buffer pointer */
 202        while (cont) {
 203                if (dc_gets(buffer, sizeof(buffer), fd) == NULL)
 204                        OUT("authentication socket read error or premature eof");
 205
 206                buffer[Ustrlen(buffer) - 1] = 0;
 207                HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
 208                nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
 209
 210                /* Code below rewritten by Kirill Miazine (km@krot.org). Only check commands that
 211                   Exim will need. Original code also failed if Dovecot server sent unknown
 212                   command. E.g. COOKIE in version 1.1 of the protocol would cause troubles. */
 213                if (Ustrcmp(args[0], US"CUID") == 0) {
 214                        CHECK_COMMAND("CUID", 1, 1);
 215                        cuid = Uatoi(args[1]);
 216                } else if (Ustrcmp(args[0], US"VERSION") == 0) {
 217                        CHECK_COMMAND("VERSION", 2, 2);
 218                        if (Uatoi(args[1]) != VERSION_MAJOR)
 219                                OUT("authentication socket protocol version mismatch");
 220                } else if (Ustrcmp(args[0], US"MECH") == 0) {
 221                        CHECK_COMMAND("MECH", 1, INT_MAX);
 222                        if (strcmpic(US args[1], ablock->public_name) == 0)
 223                                found = 1;
 224                } else if (Ustrcmp(args[0], US"DONE") == 0) {
 225                        CHECK_COMMAND("DONE", 0, 0);
 226                        cont = 0;
 227                }
 228        }
 229
 230        if (!found)
 231                goto out;
 232
 233        /* Added by PH: data must not contain tab (as it is
 234        b64 it shouldn't, but check for safety). */
 235
 236        if (Ustrchr(data, '\t') != NULL) {
 237                ret = FAIL;
 238                goto out;
 239        }
 240
 241        /* Added by PH: extra fields when TLS is in use or if the TCP/IP
 242        connection is local. */
 243
 244        if (tls_in.cipher != NULL)
 245                auth_extra_data = string_sprintf("secured\t%s%s",
 246                    tls_in.certificate_verified? "valid-client-cert" : "",
 247                    tls_in.certificate_verified? "\t" : "");
 248        else if (interface_address != NULL &&
 249                 Ustrcmp(sender_host_address, interface_address) == 0)
 250                auth_extra_data = US"secured\t";
 251
 252
 253 /****************************************************************************
 254    The code below was the original code here. It didn't work. A reading of the
 255    file auth-protocol.txt.gz that came with Dovecot 1.0_beta8 indicated that
 256    this was not right. Maybe something changed. I changed it to move the
 257    service indication into the AUTH command, and it seems to be better. PH
 258
 259        fprintf(f, "VERSION\t%d\t%d\r\nSERVICE\tSMTP\r\nCPID\t%d\r\n"
 260                "AUTH\t%d\t%s\trip=%s\tlip=%s\tresp=%s\r\n",
 261                VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
 262                ablock->public_name, sender_host_address, interface_address,
 263                data ? (char *) data : "");
 264
 265    Subsequently, the command was modified to add "secured" and "valid-client-
 266    cert" when relevant.
 267
 268    The auth protocol is documented here:
 269         http://wiki.dovecot.org/Authentication_Protocol
 270 ****************************************************************************/
 271
 272        auth_command = string_sprintf("VERSION\t%d\t%d\nCPID\t%d\n"
 273                "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tnologin\tresp=%s\n",
 274                VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
 275                ablock->public_name, auth_extra_data, sender_host_address,
 276                interface_address, data ? (char *) data : "");
 277
 278        if (write(fd, auth_command, Ustrlen(auth_command)) < 0)
 279               HDEBUG(D_auth) debug_printf("error sending auth_command: %s\n",
 280                 strerror(errno));
 281
 282        HDEBUG(D_auth) debug_printf("sent: %s", auth_command);
 283
 284        while (1) {
 285                uschar *temp;
 286                uschar *auth_id_pre = NULL;
 287                int i;
 288
 289                if (dc_gets(buffer, sizeof(buffer), fd) == NULL) {
 290                        auth_defer_msg = US"authentication socket read error or premature eof";
 291                        goto out;
 292                }
 293
 294                buffer[Ustrlen(buffer) - 1] = 0;
 295                HDEBUG(D_auth) debug_printf("received: %s\n", buffer);
 296                nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0]));
 297
 298                if (Uatoi(args[1]) != cuid)
 299                        OUT("authentication socket connection id mismatch");
 300
 301                switch (toupper(*args[0])) {
 302                case 'C':
 303                        CHECK_COMMAND("CONT", 1, 2);
 304
 305                        tmp = auth_get_no64_data(&data, US args[2]);
 306                        if (tmp != OK) {
 307                                ret = tmp;
 308                                goto out;
 309                        }
 310
 311                        /* Added by PH: data must not contain tab (as it is
 312                        b64 it shouldn't, but check for safety). */
 313
 314                        if (Ustrchr(data, '\t') != NULL) {
 315                                ret = FAIL;
 316                                goto out;
 317                        }
 318
 319                        temp = string_sprintf("CONT\t%d\t%s\n", cuid, data);
 320                        if (write(fd, temp, Ustrlen(temp)) < 0)
 321                                OUT("authentication socket write error");
 322                        break;
 323
 324                case 'F':
 325                        CHECK_COMMAND("FAIL", 1, -1);
 326
 327                        for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
 328                        {
 329                                if ( Ustrncmp(args[i], US"user=", 5) == 0 )
 330                                {
 331                                        auth_id_pre = args[i]+5;
 332                                        expand_nstring[1] = auth_vars[0] =
 333                                                string_copy(auth_id_pre); /* PH */
 334                                        expand_nlength[1] = Ustrlen(auth_id_pre);
 335                                        expand_nmax = 1;
 336                                }
 337                        }
 338
 339                        ret = FAIL;
 340                        goto out;
 341
 342                case 'O':
 343                        CHECK_COMMAND("OK", 2, -1);
 344
 345                        /*
 346                         * Search for the "user=$USER" string in the args array
 347                         * and return the proper value.
 348                         */
 349                        for (i=2; (i<nargs) && (auth_id_pre == NULL); i++)
 350                        {
 351                                if ( Ustrncmp(args[i], US"user=", 5) == 0 )
 352                                {
 353                                        auth_id_pre = args[i]+5;
 354                                        expand_nstring[1] = auth_vars[0] =
 355                                                string_copy(auth_id_pre); /* PH */
 356                                        expand_nlength[1] = Ustrlen(auth_id_pre);
 357                                        expand_nmax = 1;
 358                                }
 359                        }
 360
 361                        if (auth_id_pre == NULL)
 362                                OUT("authentication socket protocol error, username missing");
 363
 364                        ret = OK;
 365                        /* fallthrough */
 366
 367                default:
 368                        goto out;
 369                }
 370        }
 371
 372 out:
 373        /* close the socket used by dovecot */
 374        if (fd >= 0)
 375               close(fd);
 376
 377        /* Expand server_condition as an authorization check */
 378        return (ret == OK)? auth_check_serv_cond(ablock) : ret;
 379 }