s4:dsdb:password_hash: verify content if the BYPASS_PASSWORD_HASH control is used
authorStefan Metzmacher <metze@samba.org>
Tue, 7 Dec 2010 15:10:49 +0000 (16:10 +0100)
committerStefan Metzmacher <metze@samba.org>
Mon, 13 Dec 2010 15:17:36 +0000 (16:17 +0100)
Make it much harder to import bad data into the password attributes.
This isn't 100% safe, but much better than no checks.

metze

Autobuild-User: Stefan Metzmacher <metze@samba.org>
Autobuild-Date: Mon Dec 13 16:17:36 CET 2010 on sn-devel-104

source4/dsdb/samdb/ldb_modules/password_hash.c

index 4e2e96fa6507f92c82fee4b23f07b914e84833ae..75df54be294e4b3542410dd949a14e6a528bb63b 100644 (file)
@@ -151,6 +151,399 @@ struct setup_password_fields_io {
        } g;
 };
 
+static int password_hash_bypass(struct ldb_module *module, struct ldb_request *request)
+{
+       struct ldb_context *ldb = ldb_module_get_ctx(module);
+       const struct ldb_message *msg;
+       struct ldb_message_element *nte;
+       struct ldb_message_element *lme;
+       struct ldb_message_element *nthe;
+       struct ldb_message_element *lmhe;
+       struct ldb_message_element *sce;
+
+       switch (request->operation) {
+       case LDB_ADD:
+               msg = request->op.add.message;
+               break;
+       case LDB_MODIFY:
+               msg = request->op.mod.message;
+               break;
+       default:
+               return ldb_next_request(module, request);
+       }
+
+       /* nobody must touch password histories and 'supplementalCredentials' */
+       nte = dsdb_get_single_valued_attr(msg, "unicodePwd",
+                                         request->operation);
+       lme = dsdb_get_single_valued_attr(msg, "dBCSPwd",
+                                         request->operation);
+       nthe = dsdb_get_single_valued_attr(msg, "ntPwdHistory",
+                                          request->operation);
+       lmhe = dsdb_get_single_valued_attr(msg, "lmPwdHistory",
+                                          request->operation);
+       sce = dsdb_get_single_valued_attr(msg, "supplementalCredentials",
+                                         request->operation);
+
+#define CHECK_HASH_ELEMENT(e, min, max) do {\
+       if (e && e->num_values) { \
+               unsigned int _count; \
+               if (e->num_values != 1) { \
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION, \
+                                        "num_values != 1"); \
+               } \
+               if ((e->values[0].length % 16) != 0) { \
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION, \
+                                        "length % 16 != 0"); \
+               } \
+               _count = e->values[0].length / 16; \
+               if (_count < min) { \
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION, \
+                                        "count < min"); \
+               } \
+               if (_count > max) { \
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION, \
+                                        "count > max"); \
+               } \
+       } \
+} while (0)
+
+       CHECK_HASH_ELEMENT(nte, 1, 1);
+       CHECK_HASH_ELEMENT(lme, 1, 1);
+       CHECK_HASH_ELEMENT(nthe, 1, INT32_MAX);
+       CHECK_HASH_ELEMENT(lmhe, 1, INT32_MAX);
+
+       if (sce && sce->num_values) {
+               enum ndr_err_code ndr_err;
+               struct supplementalCredentialsBlob *scb;
+               struct supplementalCredentialsPackage *scpp = NULL;
+               struct supplementalCredentialsPackage *scpk = NULL;
+               struct supplementalCredentialsPackage *scpkn = NULL;
+               struct supplementalCredentialsPackage *scpct = NULL;
+               DATA_BLOB scpbp = data_blob_null;
+               DATA_BLOB scpbk = data_blob_null;
+               DATA_BLOB scpbkn = data_blob_null;
+               DATA_BLOB scpbct = data_blob_null;
+               DATA_BLOB blob;
+               uint32_t i;
+
+               if (sce->num_values != 1) {
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                        "num_values != 1");
+               }
+
+               scb = talloc_zero(request, struct supplementalCredentialsBlob);
+               if (!scb) {
+                       return ldb_module_oom(module);
+               }
+
+               ndr_err = ndr_pull_struct_blob_all(&sce->values[0], scb, scb,
+                               (ndr_pull_flags_fn_t)ndr_pull_supplementalCredentialsBlob);
+               if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                        "ndr_pull_struct_blob_all");
+               }
+
+               if (scb->sub.num_packages < 2) {
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                        "num_packages < 2");
+               }
+
+               for (i=0; i < scb->sub.num_packages; i++) {
+                       DATA_BLOB subblob;
+
+                       subblob = strhex_to_data_blob(scb, scb->sub.packages[i].data);
+                       if (subblob.data == NULL) {
+                               return ldb_module_oom(module);
+                       }
+
+                       if (strcmp(scb->sub.packages[i].name, "Packages") == 0) {
+                               if (scpp) {
+                                       return ldb_error(ldb,
+                                                        LDB_ERR_CONSTRAINT_VIOLATION,
+                                                        "Packages twice");
+                               }
+                               scpp = &scb->sub.packages[i];
+                               scpbp = subblob;
+                               continue;
+                       }
+                       if (strcmp(scb->sub.packages[i].name, "Primary:Kerberos") == 0) {
+                               if (scpk) {
+                                       return ldb_error(ldb,
+                                                        LDB_ERR_CONSTRAINT_VIOLATION,
+                                                        "Primary:Kerberos twice");
+                               }
+                               scpk = &scb->sub.packages[i];
+                               scpbk = subblob;
+                               continue;
+                       }
+                       if (strcmp(scb->sub.packages[i].name, "Primary:Kerberos-Newer-Keys") == 0) {
+                               if (scpkn) {
+                                       return ldb_error(ldb,
+                                                        LDB_ERR_CONSTRAINT_VIOLATION,
+                                                        "Primary:Kerberos-Newer-Keys twice");
+                               }
+                               scpkn = &scb->sub.packages[i];
+                               scpbkn = subblob;
+                               continue;
+                       }
+                       if (strcmp(scb->sub.packages[i].name, "Primary:CLEARTEXT") == 0) {
+                               if (scpct) {
+                                       return ldb_error(ldb,
+                                                        LDB_ERR_CONSTRAINT_VIOLATION,
+                                                        "Primary:CLEARTEXT twice");
+                               }
+                               scpct = &scb->sub.packages[i];
+                               scpbct = subblob;
+                               continue;
+                       }
+
+                       data_blob_free(&subblob);
+               }
+
+               if (scpp) {
+                       struct package_PackagesBlob *p;
+                       uint32_t n;
+
+                       p = talloc_zero(scb, struct package_PackagesBlob);
+                       if (p == NULL) {
+                               return ldb_module_oom(module);
+                       }
+
+                       ndr_err = ndr_pull_struct_blob(&scpbp, p, p,
+                                       (ndr_pull_flags_fn_t)ndr_pull_package_PackagesBlob);
+                       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "ndr_pull_struct_blob Packages");
+                       }
+
+                       if (p->names == NULL) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "Packages names == NULL");
+                       }
+
+                       for (n = 0; p->names[n]; n++) {
+                               /* noop */
+                       }
+
+                       if (scb->sub.num_packages != (n + 1)) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "Packages num_packages != num_names + 1");
+                       }
+
+                       talloc_free(p);
+               }
+
+               if (scpk) {
+                       struct package_PrimaryKerberosBlob *k;
+
+                       k = talloc_zero(scb, struct package_PrimaryKerberosBlob);
+                       if (k == NULL) {
+                               return ldb_module_oom(module);
+                       }
+
+                       ndr_err = ndr_pull_struct_blob(&scpbk, k, k,
+                                       (ndr_pull_flags_fn_t)ndr_pull_package_PrimaryKerberosBlob);
+                       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "ndr_pull_struct_blob PrimaryKerberos");
+                       }
+
+                       if (k->version != 3) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos version != 3");
+                       }
+
+                       if (k->ctr.ctr3.salt.string == NULL) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos salt == NULL");
+                       }
+
+                       if (strlen(k->ctr.ctr3.salt.string) == 0) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos strlen(salt) == 0");
+                       }
+
+                       if (k->ctr.ctr3.num_keys != 2) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos num_keys != 2");
+                       }
+
+                       if (k->ctr.ctr3.num_old_keys > k->ctr.ctr3.num_keys) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos num_old_keys > num_keys");
+                       }
+
+                       if (k->ctr.ctr3.keys[0].keytype != ENCTYPE_DES_CBC_MD5) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos key[0] != DES_CBC_MD5");
+                       }
+                       if (k->ctr.ctr3.keys[1].keytype != ENCTYPE_DES_CBC_CRC) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos key[1] != DES_CBC_CRC");
+                       }
+
+                       if (k->ctr.ctr3.keys[0].value_len != 8) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos key[0] value_len != 8");
+                       }
+                       if (k->ctr.ctr3.keys[1].value_len != 8) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos key[1] value_len != 8");
+                       }
+
+                       for (i = 0; i < k->ctr.ctr3.num_old_keys; i++) {
+                               if (k->ctr.ctr3.old_keys[i].keytype ==
+                                   k->ctr.ctr3.keys[i].keytype &&
+                                   k->ctr.ctr3.old_keys[i].value_len ==
+                                   k->ctr.ctr3.keys[i].value_len) {
+                                       continue;
+                               }
+
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryKerberos old_keys type/value_len doesn't match");
+                       }
+
+                       talloc_free(k);
+               }
+
+               if (scpkn) {
+                       struct package_PrimaryKerberosBlob *k;
+
+                       k = talloc_zero(scb, struct package_PrimaryKerberosBlob);
+                       if (k == NULL) {
+                               return ldb_module_oom(module);
+                       }
+
+                       ndr_err = ndr_pull_struct_blob(&scpbkn, k, k,
+                                       (ndr_pull_flags_fn_t)ndr_pull_package_PrimaryKerberosBlob);
+                       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "ndr_pull_struct_blob PrimaryKerberosNeverKeys");
+                       }
+
+                       if (k->version != 4) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNerverKeys version != 4");
+                       }
+
+                       if (k->ctr.ctr4.salt.string == NULL) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys salt == NULL");
+                       }
+
+                       if (strlen(k->ctr.ctr4.salt.string) == 0) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys strlen(salt) == 0");
+                       }
+
+                       if (k->ctr.ctr4.num_keys != 4) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys num_keys != 2");
+                       }
+
+                       if (k->ctr.ctr4.num_old_keys > k->ctr.ctr4.num_keys) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys num_old_keys > num_keys");
+                       }
+
+                       if (k->ctr.ctr4.num_older_keys > k->ctr.ctr4.num_old_keys) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys num_older_keys > num_old_keys");
+                       }
+
+                       if (k->ctr.ctr4.keys[0].keytype != ENCTYPE_AES256_CTS_HMAC_SHA1_96) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[0] != AES256");
+                       }
+                       if (k->ctr.ctr4.keys[1].keytype != ENCTYPE_AES128_CTS_HMAC_SHA1_96) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[1] != AES128");
+                       }
+                       if (k->ctr.ctr4.keys[2].keytype != ENCTYPE_DES_CBC_MD5) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[2] != DES_CBC_MD5");
+                       }
+                       if (k->ctr.ctr4.keys[3].keytype != ENCTYPE_DES_CBC_CRC) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[3] != DES_CBC_CRC");
+                       }
+
+                       if (k->ctr.ctr4.keys[0].value_len != 32) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[0] value_len != 32");
+                       }
+                       if (k->ctr.ctr4.keys[1].value_len != 16) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[1] value_len != 16");
+                       }
+                       if (k->ctr.ctr4.keys[2].value_len != 8) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[2] value_len != 8");
+                       }
+                       if (k->ctr.ctr4.keys[3].value_len != 8) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "KerberosNewerKeys key[3] value_len != 8");
+                       }
+
+                       /*
+                        * TODO:
+                        * Maybe we can check old and older keys here.
+                        * But we need to do some tests, if the old keys
+                        * can be taken from the PrimaryKerberos blob
+                        * (with only des keys), when the domain was upgraded
+                        * from w2k3 to w2k8.
+                        */
+
+                       talloc_free(k);
+               }
+
+               if (scpct) {
+                       struct package_PrimaryCLEARTEXTBlob *ct;
+
+                       ct = talloc_zero(scb, struct package_PrimaryCLEARTEXTBlob);
+                       if (ct == NULL) {
+                               return ldb_module_oom(module);
+                       }
+
+                       ndr_err = ndr_pull_struct_blob(&scpbct, ct, ct,
+                                       (ndr_pull_flags_fn_t)ndr_pull_package_PrimaryCLEARTEXTBlob);
+                       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "ndr_pull_struct_blob PrimaryCLEARTEXT");
+                       }
+
+                       if ((ct->cleartext.length % 2) != 0) {
+                               return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                                "PrimaryCLEARTEXT length % 2 != 0");
+                       }
+
+                       talloc_free(ct);
+               }
+
+               ndr_err = ndr_push_struct_blob(&blob, scb, scb,
+                               (ndr_push_flags_fn_t)ndr_push_supplementalCredentialsBlob);
+               if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                        "ndr_pull_struct_blob_all");
+               }
+
+               if (sce->values[0].length != blob.length) {
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                        "supplementalCredentialsBlob length differ");
+               }
+
+               if (memcmp(sce->values[0].data, blob.data, blob.length) != 0) {
+                       return ldb_error(ldb, LDB_ERR_CONSTRAINT_VIOLATION,
+                                        "supplementalCredentialsBlob memcmp differ");
+               }
+
+               talloc_free(scb);
+       }
+
+       ldb_debug(ldb, LDB_DEBUG_TRACE, "password_hash_bypass - validated\n");
+       return ldb_next_request(module, request);
+}
+
 /* Get the NT hash, and fill it in as an entry in the password history, 
    and specify it into io->g.nt_hash */
 
@@ -2322,7 +2715,7 @@ static int password_hash_add(struct ldb_module *module, struct ldb_request *req)
                /* Mark the "bypass" control as uncritical (done) */
                bypass->critical = false;
                ldb_debug(ldb, LDB_DEBUG_TRACE, "password_hash_add (bypassing)\n");
-               return ldb_next_request(module, req);
+               return password_hash_bypass(module, req);
        }
 
        /* nobody must touch password histories and 'supplementalCredentials' */
@@ -2521,7 +2914,7 @@ static int password_hash_modify(struct ldb_module *module, struct ldb_request *r
                /* Mark the "bypass" control as uncritical (done) */
                bypass->critical = false;
                ldb_debug(ldb, LDB_DEBUG_TRACE, "password_hash_modify (bypassing)\n");
-               return ldb_next_request(module, req);
+               return password_hash_bypass(module, req);
        }
 
        /* nobody must touch password histories and 'supplementalCredentials' */