libcli/auth/session.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    code to encrypt/decrypt data using the user session key
   5
   6    Copyright (C) Andrew Tridgell 2004
   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 "libcli/auth/libcli_auth.h"
  24
  25 /*
  26   encrypt or decrypt a blob of data using the user session key
  27   as used in lsa_SetSecret
  28
  29   before calling, the out blob must be initialised to be the same size
  30   as the in blob
  31 */
  32 int sess_crypt_blob(DATA_BLOB *out, const DATA_BLOB *in, const DATA_BLOB *session_key,
  33                     enum samba_gnutls_direction encrypt)
  34 {
  35         int i, k, rc;
  36
  37         if (in->length % 8 != 0) {
  38                 return GNUTLS_E_INVALID_REQUEST;
  39         }
  40
  41         for (i=0,k=0;
  42              i<in->length;
  43              i += 8, k += 7) {
  44                 uint8_t bin[8], bout[8], key[7];
  45
  46                 memcpy(bin,  &in->data[i], 8);
  47
  48                 if (k + 7 > session_key->length) {
  49                         k = (session_key->length - k);
  50                 }
  51                 memcpy(key, &session_key->data[k], 7);
  52
  53                 rc = des_crypt56_gnutls(bout, bin, key, encrypt);
  54                 if (rc != 0) {
  55                         return rc;
  56                 }
  57
  58                 memcpy(&out->data[i], bout, 8);
  59         }
  60         return 0;
  61 }
  62
  63
  64 /*
  65   a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention
  66
  67   note that we round the length to a multiple of 8. This seems to be needed for
  68   compatibility with windows
  69
  70   caller should free using data_blob_free()
  71 */
  72 DATA_BLOB sess_encrypt_string(const char *str, const DATA_BLOB *session_key)
  73 {
  74         DATA_BLOB ret, src;
  75         int slen = strlen(str);
  76         int dlen = (slen+7) & ~7;
  77         int rc;
  78
  79         src = data_blob(NULL, 8+dlen);
  80         if (!src.data) {
  81                 return data_blob(NULL, 0);
  82         }
  83
  84         ret = data_blob(NULL, 8+dlen);
  85         if (!ret.data) {
  86                 data_blob_free(&src);
  87                 return data_blob(NULL, 0);
  88         }
  89
  90         SIVAL(src.data, 0, slen);
  91         SIVAL(src.data, 4, 1);
  92         memset(src.data+8, 0,   dlen);
  93         memcpy(src.data+8, str, slen);
  94
  95         rc = sess_crypt_blob(&ret, &src, session_key, SAMBA_GNUTLS_ENCRYPT);
  96
  97         data_blob_free(&src);
  98         if (rc != 0) {
  99                 data_blob_free(&ret);
 100                 return data_blob(NULL, 0);
 101         }
 102
 103         return ret;
 104 }
 105
 106 /*
 107   a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention
 108
 109   caller should free the returned string
 110 */
 111 char *sess_decrypt_string(TALLOC_CTX *mem_ctx,
 112                           DATA_BLOB *blob, const DATA_BLOB *session_key)
 113 {
 114         DATA_BLOB out;
 115         int rc, slen;
 116         char *ret;
 117
 118         if (blob->length < 8) {
 119                 return NULL;
 120         }
 121
 122         out = data_blob_talloc(mem_ctx, NULL, blob->length);
 123         if (!out.data) {
 124                 return NULL;
 125         }
 126
 127         rc = sess_crypt_blob(&out, blob, session_key, SAMBA_GNUTLS_DECRYPT);
 128         if (rc != 0) {
 129                 data_blob_free(&out);
 130                 return NULL;
 131         }
 132
 133         if (IVAL(out.data, 4) != 1) {
 134                 DEBUG(0,("Unexpected revision number %d in session crypted string\n",
 135                          IVAL(out.data, 4)));
 136                 data_blob_free(&out);
 137                 return NULL;
 138         }
 139
 140         slen = IVAL(out.data, 0);
 141         if (slen > blob->length - 8) {
 142                 DEBUG(0,("Invalid crypt length %d\n", slen));
 143                 data_blob_free(&out);
 144                 return NULL;
 145         }
 146
 147         ret = talloc_strndup(mem_ctx, (const char *)(out.data+8), slen);
 148
 149         data_blob_free(&out);
 150
 151         DEBUG(0,("decrypted string '%s' of length %d\n", ret, slen));
 152
 153         return ret;
 154 }
 155
 156 /*
 157   a convenient wrapper around sess_crypt_blob() for DATA_BLOBs, using the LSA convention
 158
 159   note that we round the length to a multiple of 8. This seems to be needed for
 160   compatibility with windows
 161
 162   caller should free using data_blob_free()
 163 */
 164 DATA_BLOB sess_encrypt_blob(TALLOC_CTX *mem_ctx, DATA_BLOB *blob_in, const DATA_BLOB *session_key)
 165 {
 166         DATA_BLOB ret, src;
 167         int dlen = (blob_in->length+7) & ~7;
 168         int rc;
 169
 170         src = data_blob_talloc(mem_ctx, NULL, 8+dlen);
 171         if (!src.data) {
 172                 return data_blob(NULL, 0);
 173         }
 174
 175         ret = data_blob_talloc(mem_ctx, NULL, 8+dlen);
 176         if (!ret.data) {
 177                 data_blob_free(&src);
 178                 return data_blob(NULL, 0);
 179         }
 180
 181         SIVAL(src.data, 0, blob_in->length);
 182         SIVAL(src.data, 4, 1);
 183         memset(src.data+8, 0, dlen);
 184         memcpy(src.data+8, blob_in->data, blob_in->length);
 185
 186         rc = sess_crypt_blob(&ret, &src, session_key, SAMBA_GNUTLS_ENCRYPT);
 187
 188         data_blob_free(&src);
 189         if (rc != 0) {
 190                 data_blob_free(&ret);
 191                 return data_blob(NULL, 0);
 192         }
 193
 194         return ret;
 195 }
 196
 197 /*
 198   Decrypt a DATA_BLOB using the LSA convention
 199 */
 200 NTSTATUS sess_decrypt_blob(TALLOC_CTX *mem_ctx, const DATA_BLOB *blob, const DATA_BLOB *session_key,
 201                            DATA_BLOB *ret)
 202 {
 203         DATA_BLOB out;
 204         int rc, slen;
 205
 206         if (blob->length < 8) {
 207                 DEBUG(0, ("Unexpected length %d in session crypted secret (BLOB)\n",
 208                           (int)blob->length));
 209                 return NT_STATUS_INVALID_PARAMETER;
 210         }
 211
 212         out = data_blob_talloc(mem_ctx, NULL, blob->length);
 213         if (!out.data) {
 214                 return NT_STATUS_NO_MEMORY;
 215         }
 216
 217         rc = sess_crypt_blob(&out, blob, session_key, SAMBA_GNUTLS_DECRYPT);
 218         if (rc != 0) {
 219                 data_blob_free(&out);
 220                 return gnutls_error_to_ntstatus(rc, NT_STATUS_ACCESS_DISABLED_BY_POLICY_OTHER);
 221         }
 222
 223         if (IVAL(out.data, 4) != 1) {
 224                 DEBUG(2,("Unexpected revision number %d in session crypted secret (BLOB)\n",
 225                          IVAL(out.data, 4)));
 226                 return NT_STATUS_UNKNOWN_REVISION;
 227         }
 228
 229         slen = IVAL(out.data, 0);
 230         if (slen > blob->length - 8) {
 231                 DEBUG(0,("Invalid crypt length %d in session crypted secret (BLOB)\n", slen));
 232                 return NT_STATUS_WRONG_PASSWORD;
 233         }
 234
 235         *ret = data_blob_talloc(mem_ctx, out.data+8, slen);
 236         if (slen && !ret->data) {
 237                 return NT_STATUS_NO_MEMORY;
 238         }
 239
 240         data_blob_free(&out);
 241
 242         return NT_STATUS_OK;
 243 }