diff options
Diffstat (limited to 'libcli/drsuapi/repl_decrypt.c')
| -rw-r--r-- | libcli/drsuapi/repl_decrypt.c | 391 |
1 files changed, 391 insertions, 0 deletions
diff --git a/libcli/drsuapi/repl_decrypt.c b/libcli/drsuapi/repl_decrypt.c new file mode 100644 index 0000000..d289246 --- /dev/null +++ b/libcli/drsuapi/repl_decrypt.c @@ -0,0 +1,391 @@ +/* + Unix SMB/CIFS implementation. + Helper functions for applying replicated objects + + Copyright (C) Stefan Metzmacher <metze@samba.org> 2007 + Copyright (C) Andrew Bartlett <abartlet@samba.org> 2009 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. + +*/ + +#include "includes.h" +#include "../lib/util/dlinklist.h" +#include "librpc/gen_ndr/ndr_misc.h" +#include "librpc/gen_ndr/ndr_drsuapi.h" +#include "librpc/gen_ndr/ndr_drsblobs.h" +#include "zlib.h" +#include "../libcli/drsuapi/drsuapi.h" +#include "libcli/auth/libcli_auth.h" +#include "dsdb/samdb/samdb.h" + +#include "lib/crypto/gnutls_helpers.h" +#include <gnutls/gnutls.h> +#include <gnutls/crypto.h> + +static WERROR drsuapi_decrypt_attribute_value(TALLOC_CTX *mem_ctx, + const DATA_BLOB *gensec_skey, + bool rid_crypt, + uint32_t rid, + const DATA_BLOB *in, + DATA_BLOB *out) +{ + DATA_BLOB confounder; + DATA_BLOB enc_buffer; + + DATA_BLOB dec_buffer; + + uint32_t crc32_given; + uint32_t crc32_calc; + DATA_BLOB checked_buffer; + + DATA_BLOB plain_buffer; + WERROR result; + int rc; + + /* + * users with rid == 0 should not exist + */ + if (rid_crypt && rid == 0) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + + /* + * the first 16 bytes at the beginning are the confounder + * followed by the 4 byte crc32 checksum + */ + if (in->length < 20) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + confounder = data_blob_const(in->data, 16); + enc_buffer = data_blob_const(in->data + 16, in->length - 16); + + /* + * decrypt with the encryption key, being md5 over the session + * key followed by the confounder. The parameter order to + * samba_gnutls_arcfour_confounded_md5() matters for this! + * + * here the gensec session key is used and + * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key! + */ + + /* + * reference the encrypted buffer part and + * decrypt it using the created encryption key using arcfour + */ + dec_buffer = data_blob_const(enc_buffer.data, enc_buffer.length); + + rc = samba_gnutls_arcfour_confounded_md5(gensec_skey, + &confounder, + &dec_buffer, + SAMBA_GNUTLS_DECRYPT); + if (rc < 0) { + result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR); + goto out; + } + + /* + * the first 4 byte are the crc32 checksum + * of the remaining bytes + */ + crc32_given = IVAL(dec_buffer.data, 0); + crc32_calc = crc32(0, Z_NULL, 0); + crc32_calc = crc32(crc32_calc, + dec_buffer.data + 4 , + dec_buffer.length - 4); + checked_buffer = data_blob_const(dec_buffer.data + 4, dec_buffer.length - 4); + + plain_buffer = data_blob_talloc(mem_ctx, checked_buffer.data, checked_buffer.length); + W_ERROR_HAVE_NO_MEMORY(plain_buffer.data); + + if (crc32_given != crc32_calc) { + result = W_ERROR(HRES_ERROR_V(HRES_SEC_E_DECRYPT_FAILURE)); + goto out; + } + /* + * The following rid_crypt obfuscation isn't session specific + * and not really needed here, because we always know the rid of the + * user account. + * + * some attributes with this 'additional encryption' include + * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory + * + * But for the rest of samba it's easier when we remove this static + * obfuscation here + */ + if (rid_crypt) { + uint32_t i, num_hashes; + + if ((checked_buffer.length % 16) != 0) { + result = WERR_DS_DRA_INVALID_PARAMETER; + goto out; + } + + num_hashes = plain_buffer.length / 16; + for (i = 0; i < num_hashes; i++) { + uint32_t offset = i * 16; + rc = sam_rid_crypt(rid, checked_buffer.data + offset, + plain_buffer.data + offset, + SAMBA_GNUTLS_DECRYPT); + if (rc != 0) { + result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR); + goto out; + } + } + } + + *out = plain_buffer; + result = WERR_OK; +out: + return result; +} + +WERROR drsuapi_decrypt_attribute(TALLOC_CTX *mem_ctx, + const DATA_BLOB *gensec_skey, + uint32_t rid, + uint32_t dsdb_repl_flags, + struct drsuapi_DsReplicaAttribute *attr) +{ + WERROR status; + DATA_BLOB *enc_data; + DATA_BLOB plain_data; + bool rid_crypt = false; + + if (attr->value_ctr.num_values == 0) { + return WERR_OK; + } + + switch (attr->attid) { + case DRSUAPI_ATTID_dBCSPwd: + case DRSUAPI_ATTID_unicodePwd: + case DRSUAPI_ATTID_ntPwdHistory: + case DRSUAPI_ATTID_lmPwdHistory: + rid_crypt = true; + break; + case DRSUAPI_ATTID_supplementalCredentials: + case DRSUAPI_ATTID_priorValue: + case DRSUAPI_ATTID_currentValue: + case DRSUAPI_ATTID_trustAuthOutgoing: + case DRSUAPI_ATTID_trustAuthIncoming: + case DRSUAPI_ATTID_initialAuthOutgoing: + case DRSUAPI_ATTID_initialAuthIncoming: + break; + default: + return WERR_OK; + } + + if (dsdb_repl_flags & DSDB_REPL_FLAG_EXPECT_NO_SECRETS) { + return WERR_TOO_MANY_SECRETS; + } + + if (attr->value_ctr.num_values > 1) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + + if (!attr->value_ctr.values[0].blob) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + + enc_data = attr->value_ctr.values[0].blob; + + status = drsuapi_decrypt_attribute_value(mem_ctx, + gensec_skey, + rid_crypt, + rid, + enc_data, + &plain_data); + W_ERROR_NOT_OK_RETURN(status); + + talloc_free(attr->value_ctr.values[0].blob->data); + *attr->value_ctr.values[0].blob = plain_data; + + return WERR_OK; +} + +static WERROR drsuapi_encrypt_attribute_value(TALLOC_CTX *mem_ctx, + const DATA_BLOB *gensec_skey, + bool rid_crypt, + uint32_t rid, + const DATA_BLOB *in, + DATA_BLOB *out) +{ + DATA_BLOB rid_crypt_out = data_blob(NULL, 0); + DATA_BLOB confounder; + + DATA_BLOB enc_buffer; + + DATA_BLOB to_encrypt; + + uint32_t crc32_calc; + WERROR result; + int rc; + + /* + * users with rid == 0 should not exist + */ + if (rid_crypt && rid == 0) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + + /* + * The following rid_crypt obfuscation isn't session specific + * and not really needed here, because we always know the rid of the + * user account. + * + * some attributes with this 'additional encryption' include + * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory + * + * But for the rest of samba it's easier when we remove this static + * obfuscation here + */ + if (rid_crypt) { + uint32_t i, num_hashes; + rid_crypt_out = data_blob_talloc(mem_ctx, in->data, in->length); + W_ERROR_HAVE_NO_MEMORY(rid_crypt_out.data); + + if ((rid_crypt_out.length % 16) != 0) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + + num_hashes = rid_crypt_out.length / 16; + for (i = 0; i < num_hashes; i++) { + uint32_t offset = i * 16; + rc = sam_rid_crypt(rid, in->data + offset, + rid_crypt_out.data + offset, + SAMBA_GNUTLS_ENCRYPT); + if (rc != 0) { + result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR); + goto out; + } + } + in = &rid_crypt_out; + } + + /* + * the first 16 bytes at the beginning are the confounder + * followed by the 4 byte crc32 checksum + */ + + enc_buffer = data_blob_talloc(mem_ctx, NULL, in->length+20); + if (!enc_buffer.data) { + talloc_free(rid_crypt_out.data); + return WERR_NOT_ENOUGH_MEMORY; + }; + + confounder = data_blob_const(enc_buffer.data, 16); + generate_random_buffer(confounder.data, confounder.length); + + /* + * the first 4 byte are the crc32 checksum + * of the remaining bytes + */ + crc32_calc = crc32(0, Z_NULL, 0); + crc32_calc = crc32(crc32_calc, in->data, in->length); + SIVAL(enc_buffer.data, 16, crc32_calc); + + /* + * copy the plain buffer part and + * encrypt it using the created encryption key using arcfour + */ + memcpy(enc_buffer.data+20, in->data, in->length); + talloc_free(rid_crypt_out.data); + + to_encrypt = data_blob_const(enc_buffer.data+16, + enc_buffer.length-16); + + /* + * encrypt with the encryption key, being md5 over the session + * key followed by the confounder. The parameter order to + * samba_gnutls_arcfour_confounded_md5() matters for this! + * + * here the gensec session key is used and + * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key! + */ + + rc = samba_gnutls_arcfour_confounded_md5(gensec_skey, + &confounder, + &to_encrypt, + SAMBA_GNUTLS_ENCRYPT); + if (rc < 0) { + result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR); + goto out; + } + + *out = enc_buffer; + result = WERR_OK; +out: + return result; +} + +/* + encrypt a DRSUAPI attribute ready for sending over the wire + Only some attribute types are encrypted + */ +WERROR drsuapi_encrypt_attribute(TALLOC_CTX *mem_ctx, + const DATA_BLOB *gensec_skey, + uint32_t rid, + struct drsuapi_DsReplicaAttribute *attr) +{ + WERROR status; + DATA_BLOB *plain_data; + DATA_BLOB enc_data; + bool rid_crypt = false; + + if (attr->value_ctr.num_values == 0) { + return WERR_OK; + } + + switch (attr->attid) { + case DRSUAPI_ATTID_dBCSPwd: + case DRSUAPI_ATTID_unicodePwd: + case DRSUAPI_ATTID_ntPwdHistory: + case DRSUAPI_ATTID_lmPwdHistory: + rid_crypt = true; + break; + case DRSUAPI_ATTID_supplementalCredentials: + case DRSUAPI_ATTID_priorValue: + case DRSUAPI_ATTID_currentValue: + case DRSUAPI_ATTID_trustAuthOutgoing: + case DRSUAPI_ATTID_trustAuthIncoming: + case DRSUAPI_ATTID_initialAuthOutgoing: + case DRSUAPI_ATTID_initialAuthIncoming: + break; + default: + return WERR_OK; + } + + if (attr->value_ctr.num_values > 1) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + + if (!attr->value_ctr.values[0].blob) { + return WERR_DS_DRA_INVALID_PARAMETER; + } + + plain_data = attr->value_ctr.values[0].blob; + + status = drsuapi_encrypt_attribute_value(mem_ctx, + gensec_skey, + rid_crypt, + rid, + plain_data, + &enc_data); + W_ERROR_NOT_OK_RETURN(status); + + talloc_free(attr->value_ctr.values[0].blob->data); + *attr->value_ctr.values[0].blob = enc_data; + + return WERR_OK; +} + |