smtp-gssapi.h

   1 /*@ S-nail - a mail user agent derived from Berkeley Mail.
   2  *@ Implementation of SMTP GSS-API authentication according to RFC 4954.
   3  *@ TODO GSS-API should also be joined into "a VFS".
   4  *
   5  * Copyright (c) 2014 - 2018 Steffen (Daode) Nurpmeso <steffen@sdaoden.eu>.
   6  */
   7
   8 /* Derived from `imap_gssapi.h', which is:
   9  *
  10  * Copyright (c) 2004 Gunnar Ritter.
  11  * All rights reserved.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. All advertising materials mentioning features or use of this software
  22  *    must display the following acknowledgement:
  23  *    This product includes software developed by Gunnar Ritter
  24  *    and his contributors.
  25  * 4. Neither the name of Gunnar Ritter nor the names of his contributors
  26  *    may be used to endorse or promote products derived from this software
  27  *    without specific prior written permission.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY GUNNAR RITTER AND CONTRIBUTORS ``AS IS'' AND
  30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  32  * ARE DISCLAIMED.  IN NO EVENT SHALL GUNNAR RITTER OR CONTRIBUTORS BE LIABLE
  33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  39  * SUCH DAMAGE.
  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 m_DEFINED_GCC_C_NT_HOSTBASED_SERVICE
  79 # endif
  80 #else
  81 # include <gssapi.h>
  82 #endif
  83
  84 static void _smtp_gssapi_error1(char const *s, OM_uint32 code, int typ);
  85 static void _smtp_gssapi_error(char const *s, OM_uint32 maj_stat,
  86                OM_uint32 min_stat);
  87
  88 static void
  89 _smtp_gssapi_error1(char const *s, OM_uint32 code, int typ)
  90 {
  91    OM_uint32 maj_stat, min_stat;
  92    gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
  93    OM_uint32 msg_ctx = 0;
  94    NYD_ENTER;
  95
  96    do {
  97       maj_stat = gss_display_status(&min_stat, code, typ, GSS_C_NO_OID,
  98             &msg_ctx, &msg);
  99       if (maj_stat == GSS_S_COMPLETE) {
 100          n_err(_("GSS error: %s / %.*s\n"),
 101             s, (int)msg.length, (char*)msg.value);
 102          gss_release_buffer(&min_stat, &msg);
 103       } else {
 104          n_err(_("GSS error: %s / unknown\n"), s);
 105          break;
 106       }
 107    } while (msg_ctx);
 108    NYD_LEAVE;
 109 }
 110
 111 static void
 112 _smtp_gssapi_error(char const *s, OM_uint32 maj_stat, OM_uint32 min_stat)
 113 {
 114    NYD_ENTER;
 115    _smtp_gssapi_error1(s, maj_stat, GSS_C_GSS_CODE);
 116    _smtp_gssapi_error1(s, min_stat, GSS_C_MECH_CODE);
 117    NYD_LEAVE;
 118 }
 119
 120 static bool_t
 121 _smtp_gssapi(struct sock *sp, struct sendbundle *sbp, struct smtp_line *slp)
 122 {
 123    struct str in, out;
 124    gss_buffer_desc send_tok, recv_tok;
 125    gss_name_t target_name;
 126    gss_ctx_id_t gss_context;
 127    OM_uint32 maj_stat, min_stat, ret_flags;
 128    int conf_state;
 129    enum{
 130       a_F_NONE,
 131       a_F_RECV_TOK = 1u<<0,
 132       a_F_SEND_TOK = 1u<<1,
 133       a_F_TARGET_NAME = 1u<<2,
 134       a_F_GSS_CONTEXT = 1u<<3
 135    } f;
 136    bool_t ok;
 137    NYD_ENTER;
 138
 139    ok = FAL0;
 140    f = a_F_NONE;
 141
 142    if(INT_MAX - 1 - 4 <= sbp->sb_ccred.cc_user.l)
 143       goto jleave;
 144
 145    send_tok.value = n_autorec_alloc(
 146          (send_tok.length = sbp->sb_url.url_host.l + 5) +1);
 147    memcpy(send_tok.value, "smtp@", 5);
 148    memcpy((char*)send_tok.value + 5, sbp->sb_url.url_host.s,
 149       sbp->sb_url.url_host.l +1);
 150    maj_stat = gss_import_name(&min_stat, &send_tok, GSS_C_NT_HOSTBASED_SERVICE,
 151          &target_name);
 152    f |= a_F_TARGET_NAME;
 153    if (maj_stat != GSS_S_COMPLETE) {
 154       _smtp_gssapi_error(savestrbuf(send_tok.value, send_tok.length),
 155          maj_stat, min_stat);
 156       goto jleave;
 157    }
 158
 159    gss_context = GSS_C_NO_CONTEXT;
 160    maj_stat = gss_init_sec_context(&min_stat,
 161          GSS_C_NO_CREDENTIAL,
 162          &gss_context,
 163          target_name,
 164          GSS_C_NO_OID,
 165          GSS_C_MUTUAL_FLAG | GSS_C_SEQUENCE_FLAG,
 166          0,
 167          GSS_C_NO_CHANNEL_BINDINGS,
 168          GSS_C_NO_BUFFER,
 169          NULL,
 170          &send_tok,
 171          &ret_flags,
 172          NULL);
 173    f |= a_F_SEND_TOK | a_F_GSS_CONTEXT;
 174    if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED) {
 175       _smtp_gssapi_error("initializing GSS context", maj_stat, min_stat);
 176       goto jleave;
 177    }
 178
 179    _OUT(NETLINE("AUTH GSSAPI"));
 180    _ANSWER(3, FAL0, FAL0);
 181    while (maj_stat == GSS_S_CONTINUE_NEEDED) {
 182       /* Pass token obtained from first gss_init_sec_context() call */
 183       if(b64_encode_buf(&out, send_tok.value, send_tok.length,
 184             B64_SALLOC | B64_CRLF) == NULL)
 185          goto jleave;
 186       gss_release_buffer(&min_stat, &send_tok);
 187       f &= ~a_F_SEND_TOK;
 188       _OUT(out.s);
 189       _ANSWER(3, FAL0, TRU1);
 190
 191       out.s = NULL;
 192       in.s = slp->dat;
 193       in.l = slp->datlen;
 194       if(!b64_decode(&out, &in))
 195          goto jebase64;
 196       recv_tok.value = out.s;
 197       recv_tok.length = out.l;
 198       maj_stat = gss_init_sec_context(&min_stat,
 199             GSS_C_NO_CREDENTIAL,
 200             &gss_context,
 201             target_name,
 202             GSS_C_NO_OID,
 203             GSS_C_MUTUAL_FLAG | GSS_C_SEQUENCE_FLAG,
 204             0,
 205             GSS_C_NO_CHANNEL_BINDINGS,
 206             &recv_tok,
 207             NULL,
 208             &send_tok,
 209             &ret_flags,
 210             NULL);
 211       free(out.s);
 212       f |= a_F_SEND_TOK;
 213       if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED) {
 214          _smtp_gssapi_error("initializing context", maj_stat, min_stat);
 215          goto jleave;
 216       }
 217    }
 218
 219    gss_release_name(&min_stat, &target_name);
 220    f &= ~a_F_TARGET_NAME;
 221
 222    /* Pass token obtained from second gss_init_sec_context() call */
 223    if(b64_encode_buf(&out, send_tok.value, send_tok.length,
 224          B64_SALLOC | B64_CRLF) == NULL)
 225       goto jleave;
 226    _OUT(out.s);
 227
 228    gss_release_buffer(&min_stat, &send_tok);
 229    f &= ~a_F_SEND_TOK;
 230
 231    _ANSWER(3, FAL0, TRU1);
 232    out.s = NULL;
 233    in.s = slp->dat;
 234    in.l = slp->datlen;
 235    if(!b64_decode(&out, &in)){
 236 jebase64:
 237       if(out.s != NULL)
 238          free(out.s);
 239       n_err(_("Invalid base64 encoding from GSSAPI server\n"));
 240       goto jleave;
 241    }
 242    recv_tok.value = out.s;
 243    recv_tok.length = out.l;
 244    maj_stat = gss_unwrap(&min_stat, gss_context, &recv_tok, &send_tok,
 245          &conf_state, NULL);
 246    free(out.s);
 247    gss_release_buffer(&min_stat, &send_tok);
 248    /*f &= ~a_F_SEND_TOK;*/
 249    if (maj_stat != GSS_S_COMPLETE) {
 250       _smtp_gssapi_error("unwrapping data", maj_stat, min_stat);
 251       goto jleave;
 252    }
 253
 254    /* First octet: bit-mask with protection mechanisms (1 = no protection
 255     *    mechanism).
 256     * Second to fourth octet: maximum message size in network byte order.
 257     * Fifth and following octets: user name string */
 258    in.s = n_autorec_alloc((send_tok.length = 4 + sbp->sb_ccred.cc_user.l) +1);
 259    memcpy(in.s + 4, sbp->sb_ccred.cc_user.s, sbp->sb_ccred.cc_user.l +1);
 260    in.s[0] = 1;
 261    in.s[1] = 0;
 262    in.s[2] = in.s[3] = (char)0xFF;
 263    send_tok.value = in.s;
 264    maj_stat = gss_wrap(&min_stat, gss_context, 0, GSS_C_QOP_DEFAULT, &send_tok,
 265          &conf_state, &recv_tok);
 266    f |= a_F_RECV_TOK;
 267    if (maj_stat != GSS_S_COMPLETE) {
 268       _smtp_gssapi_error("wrapping data", maj_stat, min_stat);
 269       goto jleave;
 270    }
 271
 272    if(b64_encode_buf(&out, recv_tok.value, recv_tok.length,
 273          B64_SALLOC | B64_CRLF) == NULL)
 274       goto jleave;
 275    _OUT(out.s);
 276    _ANSWER(2, FAL0, FAL0);
 277
 278    ok = TRU1;
 279 jleave:
 280    if(f & a_F_RECV_TOK)
 281       gss_release_buffer(&min_stat, &recv_tok);
 282    if(f & a_F_SEND_TOK)
 283       gss_release_buffer(&min_stat, &send_tok);
 284    if(f & a_F_TARGET_NAME)
 285       gss_release_name(&min_stat, &target_name);
 286    if(f & a_F_GSS_CONTEXT)
 287       gss_delete_sec_context(&min_stat, &gss_context, GSS_C_NO_BUFFER);
 288    NYD_LEAVE;
 289    return ok;
 290 }
 291
 292 # ifdef m_DEFINED_GCC_C_NT_HOSTBASED_SERVICE
 293 #  undef GSS_C_NT_HOSTBASED_SERVICE
 294 # endif
 295 #endif /* HAVE_GSSAPI */
 296
 297 /* s-it-mode */