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         if (session_key->length < 7) {
  42                 return GNUTLS_E_INVALID_REQUEST;
  43         }
  44
  45         for (i=0,k=0;
  46              i<in->length;
  47              i += 8, k += 7) {
  48                 uint8_t bin[8], bout[8], key[7];
  49
  50                 memcpy(bin,  &in->data[i], 8);
  51
  52                 if (k + 7 > session_key->length) {
  53                         k = (session_key->length - k);
  54                 }
  55                 memcpy(key, &session_key->data[k], 7);
  56
  57                 rc = des_crypt56_gnutls(bout, bin, key, encrypt);
  58                 if (rc != 0) {
  59                         return rc;
  60                 }
  61
  62                 memcpy(&out->data[i], bout, 8);
  63         }
  64         return 0;
  65 }
  66
  67
  68 /*
  69   a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention
  70
  71   note that we round the length to a multiple of 8. This seems to be needed for
  72   compatibility with windows
  73
  74   caller should free using data_blob_free()
  75 */
  76 DATA_BLOB sess_encrypt_string(const char *str, const DATA_BLOB *session_key)
  77 {
  78         DATA_BLOB ret, src;
  79         int slen = strlen(str);
  80         int dlen = (slen+7) & ~7;
  81         int rc;
  82
  83         src = data_blob(NULL, 8+dlen);
  84         if (!src.data) {
  85                 return data_blob(NULL, 0);
  86         }
  87
  88         ret = data_blob(NULL, 8+dlen);
  89         if (!ret.data) {
  90                 data_blob_free(&src);
  91                 return data_blob(NULL, 0);
  92         }
  93
  94         SIVAL(src.data, 0, slen);
  95         SIVAL(src.data, 4, 1);
  96         memset(src.data+8, 0,   dlen);
  97         memcpy(src.data+8, str, slen);
  98
  99         rc = sess_crypt_blob(&ret, &src, session_key, SAMBA_GNUTLS_ENCRYPT);
 100
 101         data_blob_free(&src);
 102         if (rc != 0) {
 103                 data_blob_free(&ret);
 104                 return data_blob(NULL, 0);
 105         }
 106
 107         return ret;
 108 }
 109
 110 /*
 111   a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention
 112
 113   caller should free the returned string
 114 */
 115 char *sess_decrypt_string(TALLOC_CTX *mem_ctx,
 116                           DATA_BLOB *blob, const DATA_BLOB *session_key)
 117 {
 118         DATA_BLOB out;
 119         int rc, slen;
 120         char *ret;
 121
 122         if (blob->length < 8) {
 123                 return NULL;
 124         }
 125
 126         out = data_blob_talloc(mem_ctx, NULL, blob->length);
 127         if (!out.data) {
 128                 return NULL;
 129         }
 130
 131         rc = sess_crypt_blob(&out, blob, session_key, SAMBA_GNUTLS_DECRYPT);
 132         if (rc != 0) {
 133                 data_blob_free(&out);
 134                 return NULL;
 135         }
 136
 137         if (IVAL(out.data, 4) != 1) {
 138                 DEBUG(0,("Unexpected revision number %d in session encrypted string\n",
 139                          IVAL(out.data, 4)));
 140                 data_blob_free(&out);
 141                 return NULL;
 142         }
 143
 144         slen = IVAL(out.data, 0);
 145         if (slen > blob->length - 8) {
 146                 DEBUG(0,("Invalid crypt length %d\n", slen));
 147                 data_blob_free(&out);
 148                 return NULL;
 149         }
 150
 151         ret = talloc_strndup(mem_ctx, (const char *)(out.data+8), slen);
 152
 153         data_blob_free(&out);
 154
 155         DEBUG(0,("decrypted string '%s' of length %d\n", ret, slen));
 156
 157         return ret;
 158 }
 159
 160 /*
 161   a convenient wrapper around sess_crypt_blob() for DATA_BLOBs, using the LSA convention
 162
 163   note that we round the length to a multiple of 8. This seems to be needed for
 164   compatibility with windows
 165
 166   caller should free using data_blob_free()
 167 */
 168 DATA_BLOB sess_encrypt_blob(TALLOC_CTX *mem_ctx, DATA_BLOB *blob_in, const DATA_BLOB *session_key)
 169 {
 170         DATA_BLOB ret, src;
 171         int dlen = (blob_in->length+7) & ~7;
 172         int rc;
 173
 174         src = data_blob_talloc(mem_ctx, NULL, 8+dlen);
 175         if (!src.data) {
 176                 return data_blob(NULL, 0);
 177         }
 178
 179         ret = data_blob_talloc(mem_ctx, NULL, 8+dlen);
 180         if (!ret.data) {
 181                 data_blob_free(&src);
 182                 return data_blob(NULL, 0);
 183         }
 184
 185         SIVAL(src.data, 0, blob_in->length);
 186         SIVAL(src.data, 4, 1);
 187         memset(src.data+8, 0, dlen);
 188         memcpy(src.data+8, blob_in->data, blob_in->length);
 189
 190         rc = sess_crypt_blob(&ret, &src, session_key, SAMBA_GNUTLS_ENCRYPT);
 191
 192         data_blob_free(&src);
 193         if (rc != 0) {
 194                 data_blob_free(&ret);
 195                 return data_blob(NULL, 0);
 196         }
 197
 198         return ret;
 199 }
 200
 201 /*
 202   Decrypt a DATA_BLOB using the LSA convention
 203 */
 204 NTSTATUS sess_decrypt_blob(TALLOC_CTX *mem_ctx, const DATA_BLOB *blob, const DATA_BLOB *session_key,
 205                            DATA_BLOB *ret)
 206 {
 207         DATA_BLOB out;
 208         int rc, slen;
 209
 210         if (blob->length < 8) {
 211                 DEBUG(0, ("Unexpected length %d in session encrypted secret (BLOB)\n",
 212                           (int)blob->length));
 213                 return NT_STATUS_INVALID_PARAMETER;
 214         }
 215
 216         out = data_blob_talloc(mem_ctx, NULL, blob->length);
 217         if (!out.data) {
 218                 return NT_STATUS_NO_MEMORY;
 219         }
 220
 221         rc = sess_crypt_blob(&out, blob, session_key, SAMBA_GNUTLS_DECRYPT);
 222         if (rc != 0) {
 223                 data_blob_free(&out);
 224                 return gnutls_error_to_ntstatus(rc, NT_STATUS_ACCESS_DISABLED_BY_POLICY_OTHER);
 225         }
 226
 227         if (IVAL(out.data, 4) != 1) {
 228                 DEBUG(2,("Unexpected revision number %d in session encrypted secret (BLOB)\n",
 229                          IVAL(out.data, 4)));
 230                 return NT_STATUS_UNKNOWN_REVISION;
 231         }
 232
 233         slen = IVAL(out.data, 0);
 234         if (slen > blob->length - 8) {
 235                 DEBUG(0,("Invalid crypt length %d in session encrypted secret (BLOB)\n", slen));
 236                 return NT_STATUS_WRONG_PASSWORD;
 237         }
 238
 239         *ret = data_blob_talloc(mem_ctx, out.data+8, slen);
 240         if (slen && !ret->data) {
 241                 return NT_STATUS_NO_MEMORY;
 242         }
 243
 244         data_blob_free(&out);
 245
 246         return NT_STATUS_OK;
 247 }