obs-imap-gssapi.h

   1 /*@ S-nail - a mail user agent derived from Berkeley Mail.
   2  *@ Implementation of IMAP GSS-API authentication according to RFC 1731.
   3  *@ TODO GSS-API should also be joined into "a VFS".
   4  *
   5  * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
   6  * Copyright (c) 2012 - 2018 Steffen (Daode) Nurpmeso <sdaoden@users.sf.net>.
   7  */
   8 /*
   9  * Copyright (c) 2004 Gunnar Ritter.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *    This product includes software developed by Gunnar Ritter
  23  *    and his contributors.
  24  * 4. Neither the name of Gunnar Ritter nor the names of his contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY GUNNAR RITTER AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL GUNNAR RITTER OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  */
  40
  41 /*
  42  * Partially derived from sample code in:
  43  *
  44  * GSS-API Programming Guide
  45  * Part No: 816-1331-11
  46  * Sun Microsystems, Inc. 4150 Network Circle Santa Clara, CA 95054 U.S.A.
  47  *
  48  * (c) 2002 Sun Microsystems
  49  */
  50 /*
  51  * Copyright 1994 by OpenVision Technologies, Inc.
  52  *
  53  * Permission to use, copy, modify, distribute, and sell this software
  54  * and its documentation for any purpose is hereby granted without fee,
  55  * provided that the above copyright notice appears in all copies and
  56  * that both that copyright notice and this permission notice appear in
  57  * supporting documentation, and that the name of OpenVision not be used
  58  * in advertising or publicity pertaining to distribution of the software
  59  * without specific, written prior permission. OpenVision makes no
  60  * representations about the suitability of this software for any
  61  * purpose.  It is provided "as is" without express or implied warranty.
  62  *
  63  * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  64  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  65  * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  66  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
  67  * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
  68  * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  69  * PERFORMANCE OF THIS SOFTWARE.
  70  */
  71
  72 #ifdef HAVE_GSSAPI
  73 #ifndef GSSAPI_REG_INCLUDE
  74 # include <gssapi/gssapi.h>
  75 # ifdef GSSAPI_OLD_STYLE
  76 #  include <gssapi/gssapi_generic.h>
  77 #  define GSS_C_NT_HOSTBASED_SERVICE   gss_nt_service_name
  78 #  define NAIL_DEFINED_GCC_C_NT_HOSTBASED_SERVICE
  79 # endif
  80 #else
  81 # include <gssapi.h>
  82 #endif
  83
  84 static void _imap_gssapi_error1(const char *s, OM_uint32 code, int typ);
  85 static void _imap_gssapi_error(const char *s, OM_uint32 maj_stat,
  86                OM_uint32 min_stat);
  87 static char * _imap_gssapi_last_at_before_slash(char const *sp);
  88
  89 static void
  90 _imap_gssapi_error1(const char *s, OM_uint32 code, int typ)
  91 {
  92    OM_uint32 maj_stat, min_stat;
  93    gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
  94    OM_uint32 msg_ctx = 0;
  95    NYD_ENTER;
  96
  97    do {
  98       maj_stat = gss_display_status(&min_stat, code, typ, GSS_C_NO_OID,
  99             &msg_ctx, &msg);
 100       if (maj_stat == GSS_S_COMPLETE) {
 101          fprintf(stderr, "GSS error: %s / %.*s\n",
 102             s, (int)msg.length, (char*)msg.value);
 103          gss_release_buffer(&min_stat, &msg);
 104       } else {
 105          fprintf(stderr, "GSS error: %s / unknown\n", s);
 106          break;
 107       }
 108    } while (msg_ctx);
 109    NYD_LEAVE;
 110 }
 111
 112 static void
 113 _imap_gssapi_error(const char *s, OM_uint32 maj_stat, OM_uint32 min_stat)
 114 {
 115    NYD_ENTER;
 116    _imap_gssapi_error1(s, maj_stat, GSS_C_GSS_CODE);
 117    _imap_gssapi_error1(s, min_stat, GSS_C_MECH_CODE);
 118    NYD_LEAVE;
 119 }
 120
 121 static char *
 122 _imap_gssapi_last_at_before_slash(char const *sp)
 123 {
 124    char const *cp;
 125    char c;
 126    NYD_ENTER;
 127
 128    for (cp = sp; (c = *cp) != '\0'; ++cp)
 129       if (c == '/')
 130          break;
 131    while (cp > sp && *--cp != '@')
 132       ;
 133    if (*cp != '@')
 134       cp = NULL;
 135    NYD_LEAVE;
 136    return n_UNCONST(cp);
 137 }
 138
 139 static enum okay
 140 _imap_gssapi(struct mailbox *mp, struct ccred *ccred)
 141 {
 142    char o[LINESIZE];
 143    struct str in, out;
 144    gss_buffer_desc send_tok, recv_tok;
 145    gss_name_t target_name;
 146    gss_ctx_id_t gss_context;
 147    OM_uint32 maj_stat, min_stat, ret_flags;
 148    int conf_state;
 149    FILE *queuefp = NULL;
 150    char *server, *cp;
 151    enum{
 152       a_F_NONE,
 153       a_F_RECV_TOK = 1u<<0,
 154       a_F_SEND_TOK = 1u<<1,
 155       a_F_TARGET_NAME = 1u<<2,
 156       a_F_GSS_CONTEXT = 1u<<3
 157    } f;
 158    enum okay ok;
 159    NYD_X;
 160
 161    ok = STOP;
 162    f = a_F_NONE;
 163
 164    {  size_t i = strlen(mp->mb_imap_account) +1;
 165       server = salloc(i);
 166       memcpy(server, mp->mb_imap_account, i);
 167    }
 168    if (!strncmp(server, "imap://", 7))
 169       server += 7;
 170    else if (!strncmp(server, "imaps://", 8))
 171       server += 8;
 172    if ((cp = _imap_gssapi_last_at_before_slash(server)) != NULL)
 173       server = &cp[1];
 174    for (cp = server; *cp; cp++)
 175       *cp = lowerconv(*cp);
 176    send_tok.value = n_autorec_alloc(
 177          (send_tok.length = strlen(server) -1 + 5) +1);
 178    snprintf(send_tok.value, send_tok.length, "imap@%s", server);
 179    maj_stat = gss_import_name(&min_stat, &send_tok, GSS_C_NT_HOSTBASED_SERVICE,
 180          &target_name);
 181    f |= a_F_TARGET_NAME;
 182    if (maj_stat != GSS_S_COMPLETE) {
 183       _imap_gssapi_error(savestrbuf(send_tok.value, send_tok.length),
 184          maj_stat, min_stat);
 185       goto jleave;
 186    }
 187
 188    gss_context = GSS_C_NO_CONTEXT;
 189    maj_stat = gss_init_sec_context(&min_stat,
 190          GSS_C_NO_CREDENTIAL,
 191          &gss_context,
 192          target_name,
 193          GSS_C_NO_OID,
 194          GSS_C_MUTUAL_FLAG | GSS_C_SEQUENCE_FLAG,
 195          0,
 196          GSS_C_NO_CHANNEL_BINDINGS,
 197          GSS_C_NO_BUFFER,
 198          NULL,
 199          &send_tok,
 200          &ret_flags,
 201          NULL);
 202    f |= a_F_SEND_TOK | a_F_GSS_CONTEXT;
 203    if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED) {
 204       _imap_gssapi_error("initializing GSS context", maj_stat, min_stat);
 205       goto jleave;
 206    }
 207
 208    snprintf(o, sizeof o, "%s AUTHENTICATE GSSAPI\r\n", tag(1));
 209    IMAP_OUT(o, 0, goto jleave);
 210
 211    /*
 212     * No response data expected.
 213     */
 214    imap_answer(mp, 1);
 215    if (response_type != RESPONSE_CONT)
 216       goto jleave;
 217    while (maj_stat == GSS_S_CONTINUE_NEEDED) {
 218       /* Pass token obtained from first gss_init_sec_context() call. */
 219       if(b64_encode_buf(&out, send_tok.value, send_tok.length,
 220             B64_SALLOC | B64_CRLF) == NULL)
 221          goto jleave;
 222       gss_release_buffer(&min_stat, &send_tok);
 223       f &= ~a_F_SEND_TOK;
 224       IMAP_OUT(out.s, 0, goto jleave);
 225       imap_answer(mp, 1);
 226       if (response_type != RESPONSE_CONT)
 227          goto jleave;
 228       out.s = NULL;
 229       in.s = responded_text;
 230       in.l = strlen(responded_text);
 231       if(!b64_decode(&out, &in))
 232          goto jebase64;
 233       recv_tok.value = out.s;
 234       recv_tok.length = out.l;
 235       maj_stat = gss_init_sec_context(&min_stat,
 236             GSS_C_NO_CREDENTIAL,
 237             &gss_context,
 238             target_name,
 239             GSS_C_NO_OID,
 240             GSS_C_MUTUAL_FLAG | GSS_C_SEQUENCE_FLAG,
 241             0,
 242             GSS_C_NO_CHANNEL_BINDINGS,
 243             &recv_tok,
 244             NULL,
 245             &send_tok,
 246             &ret_flags,
 247             NULL);
 248       free(out.s);
 249       f |= a_F_SEND_TOK;
 250       if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED) {
 251          _imap_gssapi_error("initializing context", maj_stat, min_stat);
 252          goto jleave;
 253       }
 254    }
 255
 256    gss_release_name(&min_stat, &target_name);
 257    f &= ~a_F_TARGET_NAME;
 258
 259    /* Pass token obtained from second gss_init_sec_context() call */
 260    if(b64_encode_buf(&out, send_tok.value, send_tok.length,
 261          B64_SALLOC | B64_CRLF) == NULL)
 262       goto jleave;
 263    IMAP_OUT(out.s, 0, goto jleave);
 264
 265    gss_release_buffer(&min_stat, &send_tok);
 266    f &= ~a_F_SEND_TOK;
 267
 268    /*
 269     * First octet: bit-mask with protection mechanisms.
 270     * Second to fourth octet: maximum message size in network byte order.
 271     *
 272     * This code currently does not care about the values.
 273     */
 274    imap_answer(mp, 1);
 275    if (response_type != RESPONSE_CONT)
 276       goto jleave;
 277    out.s = NULL;
 278    in.s = responded_text;
 279    in.l = strlen(responded_text);
 280    if(!b64_decode(&out, &in)){
 281 jebase64:
 282       if(out.s != NULL)
 283          free(out.s);
 284       n_err(_("Invalid base64 encoding from GSSAPI server\n"));
 285       goto jleave;
 286    }
 287    recv_tok.value = out.s;
 288    recv_tok.length = out.l;
 289    maj_stat = gss_unwrap(&min_stat, gss_context, &recv_tok, &send_tok,
 290          &conf_state, NULL);
 291    free(out.s);
 292    gss_release_buffer(&min_stat, &send_tok);
 293    /*f &= ~a_F_SEND_TOK;*/
 294    if (maj_stat != GSS_S_COMPLETE) {
 295       _imap_gssapi_error("unwrapping data", maj_stat, min_stat);
 296       goto jleave;
 297    }
 298
 299    /* First octet: bit-mask with protection mechanisms (1 = no protection
 300     *    mechanism).
 301     * Second to fourth octet: maximum message size in network byte order.
 302     * Fifth and following octets: user name string.
 303     */
 304    o[0] = 1;
 305    o[1] = 0;
 306    o[2] = o[3] = (char)0377;
 307    snprintf(&o[4], sizeof o - 4, "%s", ccred->cc_user.s);
 308    send_tok.value = o;
 309    send_tok.length = strlen(&o[4]) -1 + 4;
 310    maj_stat = gss_wrap(&min_stat, gss_context, 0, GSS_C_QOP_DEFAULT, &send_tok,
 311          &conf_state, &recv_tok);
 312    f |= a_F_RECV_TOK;
 313    if (maj_stat != GSS_S_COMPLETE) {
 314       _imap_gssapi_error("wrapping data", maj_stat, min_stat);
 315       goto jleave;
 316    }
 317
 318    if(b64_encode_buf(&out, recv_tok.value, recv_tok.length,
 319          B64_SALLOC | B64_CRLF) == NULL)
 320       goto jleave;
 321    IMAP_OUT(out.s, MB_COMD, goto jleave);
 322
 323    while (mp->mb_active & MB_COMD)
 324       ok = imap_answer(mp, 1);
 325 jleave:
 326    if(f & a_F_RECV_TOK)
 327       gss_release_buffer(&min_stat, &recv_tok);
 328    if(f & a_F_SEND_TOK)
 329       gss_release_buffer(&min_stat, &send_tok);
 330    if(f & a_F_TARGET_NAME)
 331       gss_release_name(&min_stat, &target_name);
 332    if(f & a_F_GSS_CONTEXT)
 333       gss_delete_sec_context(&min_stat, &gss_context, GSS_C_NO_BUFFER);
 334    return ok;
 335 }
 336
 337 # ifdef NAIL_DEFINED_GCC_C_NT_HOSTBASED_SERVICE
 338 #  undef GSS_C_NT_HOSTBASED_SERVICE
 339 # endif
 340 #endif /* HAVE_GSSAPI */
 341
 342 /* s-it-mode */