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".  TODO LEAKS (error path)
   4  *
   5  * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
   6  * Copyright (c) 2012 - 2015 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", s, (char*)msg.value);
 102          if (msg.length != 0)
 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 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, *token_ptr;
 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 okay ok = STOP;
 152    NYD_X;
 153
 154    {  size_t i = strlen(mp->mb_imap_account) +1;
 155       server = salloc(i);
 156       memcpy(server, mp->mb_imap_account, i);
 157    }
 158    if (!strncmp(server, "imap://", 7))
 159       server += 7;
 160    else if (!strncmp(server, "imaps://", 8))
 161       server += 8;
 162    if ((cp = _imap_gssapi_last_at_before_slash(server)) != NULL)
 163       server = &cp[1];
 164    for (cp = server; *cp; cp++)
 165       *cp = lowerconv(*cp);
 166    send_tok.value = salloc(send_tok.length = strlen(server) + 6);
 167    snprintf(send_tok.value, send_tok.length, "imap@%s", server);
 168    maj_stat = gss_import_name(&min_stat, &send_tok, GSS_C_NT_HOSTBASED_SERVICE,
 169          &target_name);
 170    if (maj_stat != GSS_S_COMPLETE) {
 171       _imap_gssapi_error(send_tok.value, maj_stat, min_stat);
 172       return STOP;
 173    }
 174    token_ptr = GSS_C_NO_BUFFER;
 175    gss_context = GSS_C_NO_CONTEXT;
 176    maj_stat = gss_init_sec_context(&min_stat,
 177          GSS_C_NO_CREDENTIAL,
 178          &gss_context,
 179          target_name,
 180          GSS_C_NO_OID,
 181          GSS_C_MUTUAL_FLAG|GSS_C_SEQUENCE_FLAG,
 182          0,
 183          GSS_C_NO_CHANNEL_BINDINGS,
 184          token_ptr,
 185          NULL,
 186          &send_tok,
 187          &ret_flags,
 188          NULL);
 189    if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED) {
 190       _imap_gssapi_error("initializing GSS context", maj_stat, min_stat);
 191       gss_release_name(&min_stat, &target_name);
 192       return STOP;
 193    }
 194    snprintf(o, sizeof o, "%s AUTHENTICATE GSSAPI\r\n", tag(1));
 195    IMAP_OUT(o, 0, return STOP);
 196    /*
 197     * No response data expected.
 198     */
 199    imap_answer(mp, 1);
 200    if (response_type != RESPONSE_CONT)
 201       return STOP;
 202    while (maj_stat == GSS_S_CONTINUE_NEEDED) {
 203       /*
 204        * Pass token obtained from first gss_init_sec_context() call.
 205        */
 206       b64_encode_buf(&out, send_tok.value, send_tok.length,
 207          B64_SALLOC | B64_CRLF);
 208       gss_release_buffer(&min_stat, &send_tok);
 209       IMAP_OUT(out.s, 0, return STOP);
 210       imap_answer(mp, 1);
 211       if (response_type != RESPONSE_CONT)
 212          return STOP;
 213       out.s = NULL;
 214       in.s = responded_text;
 215       in.l = strlen(responded_text);
 216       b64_decode(&out, &in, NULL);
 217       recv_tok.value = out.s;
 218       recv_tok.length = out.l;
 219       token_ptr = &recv_tok;
 220       maj_stat = gss_init_sec_context(&min_stat,
 221             GSS_C_NO_CREDENTIAL,
 222             &gss_context,
 223             target_name,
 224             GSS_C_NO_OID,
 225             GSS_C_MUTUAL_FLAG|GSS_C_SEQUENCE_FLAG,
 226             0,
 227             GSS_C_NO_CHANNEL_BINDINGS,
 228             token_ptr,
 229             NULL,
 230             &send_tok,
 231             &ret_flags,
 232             NULL);
 233       free(out.s);
 234       if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED) {
 235          _imap_gssapi_error("initializing context", maj_stat, min_stat);
 236          gss_release_name(&min_stat, &target_name);
 237          return STOP;
 238       }
 239    }
 240    /*
 241     * Pass token obtained from second gss_init_sec_context() call.
 242     */
 243    gss_release_name(&min_stat, &target_name);
 244    b64_encode_buf(&out, send_tok.value, send_tok.length, B64_SALLOC | B64_CRLF);
 245    gss_release_buffer(&min_stat, &send_tok);
 246    IMAP_OUT(out.s, 0, return STOP);
 247    /*
 248     * First octet: bit-mask with protection mechanisms.
 249     * Second to fourth octet: maximum message size in network byte order.
 250     *
 251     * This code currently does not care about the values.
 252     */
 253    imap_answer(mp, 1);
 254    if (response_type != RESPONSE_CONT)
 255       return STOP;
 256    out.s = NULL;
 257    in.s = responded_text;
 258    in.l = strlen(responded_text);
 259    b64_decode(&out, &in, NULL);
 260    recv_tok.value = out.s;
 261    recv_tok.length = out.l;
 262    maj_stat = gss_unwrap(&min_stat, gss_context, &recv_tok, &send_tok,
 263          &conf_state, NULL);
 264    free(out.s);
 265    if (maj_stat != GSS_S_COMPLETE) {
 266       _imap_gssapi_error("unwrapping data", maj_stat, min_stat);
 267       return STOP;
 268    }
 269    /*
 270     * First octet: bit-mask with protection mechanisms (1 = no protection
 271     *    mechanism).
 272     * Second to fourth octet: maximum message size in network byte order.
 273     * Fifth and following octets: user name string.
 274     */
 275    o[0] = 1;
 276    o[1] = 0;
 277    o[2] = o[3] = (char)0377;
 278    snprintf(&o[4], sizeof o - 4, "%s", ccred->cc_user.s);
 279    send_tok.value = o;
 280    send_tok.length = strlen(&o[4]) + 5;
 281    maj_stat = gss_wrap(&min_stat, gss_context, 0, GSS_C_QOP_DEFAULT, &send_tok,
 282          &conf_state, &recv_tok);
 283    if (maj_stat != GSS_S_COMPLETE) {
 284       _imap_gssapi_error("wrapping data", maj_stat, min_stat);
 285       return STOP;
 286    }
 287    b64_encode_buf(&out, recv_tok.value, recv_tok.length, B64_SALLOC | B64_CRLF);
 288    IMAP_OUT(out.s, MB_COMD, return STOP);
 289    while (mp->mb_active & MB_COMD)
 290       ok = imap_answer(mp, 1);
 291    gss_delete_sec_context(&min_stat, &gss_context, &recv_tok);
 292    gss_release_buffer(&min_stat, &recv_tok);
 293    return ok;
 294 }
 295
 296 # ifdef NAIL_DEFINED_GCC_C_NT_HOSTBASED_SERVICE
 297 #  undef GSS_C_NT_HOSTBASED_SERVICE
 298 # endif
 299 #endif /* HAVE_GSSAPI */
 300
 301 /* s-it-mode */