source4/smb_server/smb/signing.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (C) Andrew Tridgell              2004
   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 by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21 #include "smb_server/smb_server.h"
  22 #include "libcli/raw/libcliraw.h"
  23 #include "libcli/raw/raw_proto.h"
  24 #include "param/param.h"
  25
  26
  27 /*
  28   sign an outgoing packet
  29 */
  30 void smbsrv_sign_packet(struct smbsrv_request *req)
  31 {
  32 #if 0
  33         /* enable this when packet signing is preventing you working out why valgrind
  34            says that data is uninitialised */
  35         file_save("pkt.dat", req->out.buffer, req->out.size);
  36 #endif
  37
  38         switch (req->smb_conn->signing.signing_state) {
  39         case SMB_SIGNING_ENGINE_OFF:
  40                 break;
  41
  42         case SMB_SIGNING_ENGINE_BSRSPYL:
  43                 /* mark the packet as signed - BEFORE we sign it...*/
  44                 mark_packet_signed(&req->out);
  45
  46                 /* I wonder what BSRSPYL stands for - but this is what MS
  47                    actually sends! */
  48                 memcpy((req->out.hdr + HDR_SS_FIELD), "BSRSPYL ", 8);
  49                 break;
  50
  51         case SMB_SIGNING_ENGINE_ON:
  52
  53                 sign_outgoing_message(&req->out,
  54                                       &req->smb_conn->signing.mac_key,
  55                                       req->seq_num+1);
  56                 break;
  57         }
  58         return;
  59 }
  60
  61
  62
  63 /*
  64   setup the signing key for a connection. Called after authentication succeeds
  65   in a session setup
  66 */
  67 bool smbsrv_setup_signing(struct smbsrv_connection *smb_conn,
  68                           DATA_BLOB *session_key,
  69                           DATA_BLOB *response)
  70 {
  71         if (!set_smb_signing_common(&smb_conn->signing)) {
  72                 return false;
  73         }
  74         return smbcli_simple_set_signing(smb_conn,
  75                                          &smb_conn->signing, session_key, response);
  76 }
  77
  78 bool smbsrv_init_signing(struct smbsrv_connection *smb_conn)
  79 {
  80         smb_conn->signing.mac_key = data_blob(NULL, 0);
  81         if (!smbcli_set_signing_off(&smb_conn->signing)) {
  82                 return false;
  83         }
  84
  85         smb_conn->signing.allow_smb_signing
  86                 = lpcfg_server_signing_allowed(smb_conn->lp_ctx,
  87                                                &smb_conn->signing.mandatory_signing);
  88         return true;
  89 }
  90
  91 /*
  92   allocate a sequence number to a request
  93 */
  94 static void req_signing_alloc_seq_num(struct smbsrv_request *req)
  95 {
  96         req->seq_num = req->smb_conn->signing.next_seq_num;
  97
  98         if (req->smb_conn->signing.signing_state != SMB_SIGNING_ENGINE_OFF) {
  99                 req->smb_conn->signing.next_seq_num += 2;
 100         }
 101 }
 102
 103 /*
 104   called for requests that do not produce a reply of their own
 105 */
 106 void smbsrv_signing_no_reply(struct smbsrv_request *req)
 107 {
 108         if (req->smb_conn->signing.signing_state != SMB_SIGNING_ENGINE_OFF) {
 109                 req->smb_conn->signing.next_seq_num--;
 110         }
 111 }
 112
 113 /***********************************************************
 114  SMB signing - Simple implementation - check a MAC sent by client
 115 ************************************************************/
 116 /**
 117  * Check a packet supplied by the server.
 118  * @return false if we had an established signing connection
 119  *         which had a back checksum, true otherwise
 120  */
 121 bool smbsrv_signing_check_incoming(struct smbsrv_request *req)
 122 {
 123         bool good;
 124
 125         req_signing_alloc_seq_num(req);
 126
 127         switch (req->smb_conn->signing.signing_state)
 128         {
 129         case SMB_SIGNING_ENGINE_OFF:
 130                 return true;
 131         case SMB_SIGNING_ENGINE_BSRSPYL:
 132         case SMB_SIGNING_ENGINE_ON:
 133         {
 134                 if (req->in.size < (HDR_SS_FIELD + 8)) {
 135                         return false;
 136                 } else {
 137                         good = check_signed_incoming_message(&req->in,
 138                                                              &req->smb_conn->signing.mac_key,
 139                                                              req->seq_num);
 140
 141                         return signing_good(&req->smb_conn->signing,
 142                                             req->seq_num+1, good);
 143                 }
 144         }
 145         }
 146         return false;
 147 }