CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: log warnings about unsecure configu...

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Günther Deschner <gd@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>

diff --git a/source3/rpc_server/netlogon/srv_netlog_nt.c b/source3/rpc_server/netlogon/srv_netlog_nt.c
index 63dd9dc0d5f48a36ea5a8d1e70a7d7b6a92afd6d..3221ebaa2e2e62f49f20b82987c089a97c02a07e 100644 (file)
--- a/source3/rpc_server/netlogon/srv_netlog_nt.c
+++ b/source3/rpc_server/netlogon/srv_netlog_nt.c
@@ -1073,11 +1073,13 @@ static NTSTATUS netr_creds_server_step_check(struct pipes_struct *p,
        NTSTATUS status;
        bool schannel_global_required = (lp_server_schannel() == true) ? true:false;
        bool schannel_required = schannel_global_required;
+       const char *explicit_opt = NULL;
        struct loadparm_context *lp_ctx;
        struct netlogon_creds_CredentialState *creds = NULL;
        enum dcerpc_AuthType auth_type = DCERPC_AUTH_TYPE_NONE;
        uint16_t opnum = p->opnum;
        const char *opname = "<unknown>";
+       static bool warned_global_once = false;
 
        if (creds_out != NULL) {
                *creds_out = NULL;
@@ -1105,10 +1107,20 @@ static NTSTATUS netr_creds_server_step_check(struct pipes_struct *p,
                return status;
        }
 
-       schannel_required = lp_parm_bool(GLOBAL_SECTION_SNUM,
-                                        "server require schannel",
-                                        creds->account_name,
-                                        schannel_global_required);
+       /*
+        * We don't use lp_parm_bool(), as we
+        * need the explicit_opt pointer in order to
+        * adjust the debug messages.
+        */
+
+       explicit_opt = lp_parm_const_string(GLOBAL_SECTION_SNUM,
+                                           "server require schannel",
+                                           creds->account_name,
+                                           NULL);
+       if (explicit_opt != NULL) {
+               schannel_required = lp_bool(explicit_opt);
+       }
+
        if (schannel_required) {
                if (auth_type == DCERPC_AUTH_TYPE_SCHANNEL) {
                        *creds_out = creds;
@@ -1121,11 +1133,61 @@ static NTSTATUS netr_creds_server_step_check(struct pipes_struct *p,
                        opname, opnum,
                        log_escape(mem_ctx, creds->account_name),
                        log_escape(mem_ctx, creds->computer_name));
+               DBG_ERR("CVE-2020-1472(ZeroLogon): Check if option "
+                       "'server require schannel:%s = no' is needed! \n",
+                       log_escape(mem_ctx, creds->account_name));
                TALLOC_FREE(creds);
                ZERO_STRUCTP(return_authenticator);
                return NT_STATUS_ACCESS_DENIED;
        }
 
+       if (!schannel_global_required && !warned_global_once) {
+               /*
+                * We want admins to notice their misconfiguration!
+                */
+               DBG_ERR("CVE-2020-1472(ZeroLogon): "
+                       "Please configure 'server schannel = yes', "
+                       "See https://bugzilla.samba.org/show_bug.cgi?id=14497\n");
+               warned_global_once = true;
+       }
+
+       if (auth_type == DCERPC_AUTH_TYPE_SCHANNEL) {
+               DBG_ERR("CVE-2020-1472(ZeroLogon): "
+                       "%s request (opnum[%u]) WITH schannel from "
+                       "client_account[%s] client_computer_name[%s]\n",
+                       opname, opnum,
+                       log_escape(mem_ctx, creds->account_name),
+                       log_escape(mem_ctx, creds->computer_name));
+               DBG_ERR("CVE-2020-1472(ZeroLogon): "
+                       "Option 'server require schannel:%s = no' not needed!?\n",
+                       log_escape(mem_ctx, creds->account_name));
+
+               *creds_out = creds;
+               return NT_STATUS_OK;
+       }
+
+       if (explicit_opt != NULL) {
+               DBG_INFO("CVE-2020-1472(ZeroLogon): "
+                        "%s request (opnum[%u]) without schannel from "
+                        "client_account[%s] client_computer_name[%s]\n",
+                        opname, opnum,
+                        log_escape(mem_ctx, creds->account_name),
+                        log_escape(mem_ctx, creds->computer_name));
+               DBG_INFO("CVE-2020-1472(ZeroLogon): "
+                        "Option 'server require schannel:%s = no' still needed!\n",
+                        log_escape(mem_ctx, creds->account_name));
+       } else {
+               DBG_ERR("CVE-2020-1472(ZeroLogon): "
+                       "%s request (opnum[%u]) without schannel from "
+                       "client_account[%s] client_computer_name[%s]\n",
+                       opname, opnum,
+                       log_escape(mem_ctx, creds->account_name),
+                       log_escape(mem_ctx, creds->computer_name));
+               DBG_ERR("CVE-2020-1472(ZeroLogon): Check if option "
+                       "'server require schannel:%s = no' might be needed!\n",
+                       log_escape(mem_ctx, creds->account_name));
+       }
+
        *creds_out = creds;
        return NT_STATUS_OK;
 }