source3/smbd/signing.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    SMB Signing Code
   4    Copyright (C) Jeremy Allison 2003.
   5    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2002-2003
   6    Copyright (C) Stefan Metzmacher 2009
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "smbd/globals.h"
  24
  25
  26 /***********************************************************
  27  Called to validate an incoming packet from the client.
  28 ************************************************************/
  29
  30 bool srv_check_sign_mac(struct smbd_server_connection *conn,
  31                         const char *inbuf, uint32_t *seqnum,
  32                         bool trusted_channel)
  33 {
  34         /* Check if it's a non-session message. */
  35         if(CVAL(inbuf,0)) {
  36                 return true;
  37         }
  38
  39         if (trusted_channel) {
  40                 NTSTATUS status;
  41
  42                 if (smb_len(inbuf) < (smb_ss_field + 8 - 4)) {
  43                         DEBUG(1,("smb_signing_check_pdu: Can't check signature "
  44                                  "on short packet! smb_len = %u\n",
  45                                  smb_len(inbuf)));
  46                         return false;
  47                 }
  48
  49                 status = NT_STATUS(IVAL(inbuf, smb_ss_field + 4));
  50                 if (!NT_STATUS_IS_OK(status)) {
  51                         DEBUG(1,("smb_signing_check_pdu: trusted channel passed %s\n",
  52                                  nt_errstr(status)));
  53                         return false;
  54                 }
  55
  56                 *seqnum = IVAL(inbuf, smb_ss_field);
  57                 return true;
  58         }
  59
  60         *seqnum = smb_signing_next_seqnum(conn->smb1.signing_state, false);
  61         return smb_signing_check_pdu(conn->smb1.signing_state,
  62                                      (const uint8_t *)inbuf,
  63                                      *seqnum);
  64 }
  65
  66 /***********************************************************
  67  Called to sign an outgoing packet to the client.
  68 ************************************************************/
  69
  70 void srv_calculate_sign_mac(struct smbd_server_connection *conn,
  71                             char *outbuf, uint32_t seqnum)
  72 {
  73         /* Check if it's a non-session message. */
  74         if(CVAL(outbuf,0)) {
  75                 return;
  76         }
  77
  78         smb_signing_sign_pdu(conn->smb1.signing_state, (uint8_t *)outbuf, seqnum);
  79 }
  80
  81
  82 /***********************************************************
  83  Called to indicate a oneway request
  84 ************************************************************/
  85 void srv_cancel_sign_response(struct smbd_server_connection *conn)
  86 {
  87         smb_signing_cancel_reply(conn->smb1.signing_state, true);
  88 }
  89
  90 struct smbd_shm_signing {
  91         size_t shm_size;
  92         uint8_t *shm_pointer;
  93
  94         /* we know the signing engine will only allocate 2 chunks */
  95         uint8_t *ptr1;
  96         size_t len1;
  97         uint8_t *ptr2;
  98         size_t len2;
  99 };
 100
 101 static void *smbd_shm_signing_alloc(TALLOC_CTX *mem_ctx, size_t len)
 102 {
 103         struct smbd_shm_signing *s = talloc_get_type_abort(mem_ctx,
 104                                      struct smbd_shm_signing);
 105
 106         if (s->ptr1 == NULL) {
 107                 s->len1 = len;
 108                 if (len % 8) {
 109                         s->len1 += (8 - (len % 8));
 110                 }
 111                 if (s->len1 > s->shm_size) {
 112                         s->len1 = 0;
 113                         errno = ENOMEM;
 114                         return NULL;
 115                 }
 116                 s->ptr1 = s->shm_pointer;
 117                 return s->ptr1;
 118         }
 119
 120         if (s->ptr2 == NULL) {
 121                 s->len2 = len;
 122                 if (s->len2 > (s->shm_size - s->len1)) {
 123                         s->len2 = 0;
 124                         errno = ENOMEM;
 125                         return NULL;
 126                 }
 127                 s->ptr2 = s->shm_pointer + s->len1;
 128                 return s->ptr2;
 129         }
 130
 131         errno = ENOMEM;
 132         return NULL;
 133 }
 134
 135 static void smbd_shm_signing_free(TALLOC_CTX *mem_ctx, void *ptr)
 136 {
 137         struct smbd_shm_signing *s = talloc_get_type_abort(mem_ctx,
 138                                      struct smbd_shm_signing);
 139
 140         if (s->ptr2 == ptr) {
 141                 s->ptr2 = NULL;
 142                 s->len2 = 0;
 143         }
 144 }
 145
 146 /***********************************************************
 147  Called by server negprot when signing has been negotiated.
 148 ************************************************************/
 149
 150 bool srv_init_signing(struct smbd_server_connection *conn)
 151 {
 152         bool allowed = true;
 153         bool mandatory = false;
 154
 155         switch (lp_server_signing()) {
 156         case Required:
 157                 mandatory = true;
 158                 break;
 159         case Auto:
 160                 break;
 161         case True:
 162                 break;
 163         case False:
 164                 allowed = false;
 165                 break;
 166         }
 167
 168         if (lp_async_smb_echo_handler()) {
 169                 struct smbd_shm_signing *s;
 170
 171                 /* setup the signing state in shared memory */
 172                 s = talloc_zero(smbd_event_context(), struct smbd_shm_signing);
 173                 if (s == NULL) {
 174                         return false;
 175                 }
 176                 s->shm_size = 4096;
 177                 s->shm_pointer =
 178                         (uint8_t *)allocate_anonymous_shared(s->shm_size);
 179                 if (s->shm_pointer == NULL) {
 180                         talloc_free(s);
 181                         return false;
 182                 }
 183                 conn->smb1.signing_state = smb_signing_init_ex(s,
 184                                                         allowed, mandatory,
 185                                                         smbd_shm_signing_alloc,
 186                                                         smbd_shm_signing_free);
 187                 if (!conn->smb1.signing_state) {
 188                         return false;
 189                 }
 190                 return true;
 191         }
 192
 193         conn->smb1.signing_state = smb_signing_init(smbd_event_context(),
 194                                                     allowed, mandatory);
 195         if (!conn->smb1.signing_state) {
 196                 return false;
 197         }
 198
 199         return true;
 200 }
 201
 202 void srv_set_signing_negotiated(struct smbd_server_connection *conn)
 203 {
 204         smb_signing_set_negotiated(conn->smb1.signing_state);
 205 }
 206
 207 /***********************************************************
 208  Returns whether signing is active. We can't use sendfile or raw
 209  reads/writes if it is.
 210 ************************************************************/
 211
 212 bool srv_is_signing_active(struct smbd_server_connection *conn)
 213 {
 214         return smb_signing_is_active(conn->smb1.signing_state);
 215 }
 216
 217
 218 /***********************************************************
 219  Returns whether signing is negotiated. We can't use it unless it was
 220  in the negprot.
 221 ************************************************************/
 222
 223 bool srv_is_signing_negotiated(struct smbd_server_connection *conn)
 224 {
 225         return smb_signing_is_negotiated(conn->smb1.signing_state);
 226 }
 227
 228 /***********************************************************
 229  Turn on signing from this packet onwards.
 230 ************************************************************/
 231
 232 void srv_set_signing(struct smbd_server_connection *conn,
 233                      const DATA_BLOB user_session_key,
 234                      const DATA_BLOB response)
 235 {
 236         bool negotiated;
 237         bool mandatory;
 238
 239         if (!user_session_key.length)
 240                 return;
 241
 242         negotiated = smb_signing_is_negotiated(conn->smb1.signing_state);
 243         mandatory = smb_signing_is_mandatory(conn->smb1.signing_state);
 244
 245         if (!negotiated && !mandatory) {
 246                 DEBUG(5,("srv_set_signing: signing negotiated = %u, "
 247                          "mandatory_signing = %u. Not allowing smb signing.\n",
 248                          negotiated, mandatory));
 249                 return;
 250         }
 251
 252         if (!smb_signing_activate(conn->smb1.signing_state,
 253                                   user_session_key, response)) {
 254                 return;
 255         }
 256
 257         DEBUG(3,("srv_set_signing: turning on SMB signing: "
 258                  "signing negotiated = %u, mandatory_signing = %u.\n",
 259                  negotiated, mandatory));
 260 }
 261