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samba/backport-0022-CVE-2022-38023.patch

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fix CVE-2022-38023 CVE-2022-37966 CVE-2022-37967
2022-12-29 07:17:40 +00:00
From 3c9bb4c8d233909e825818f7975d734824465d50 Mon Sep 17 00:00:00 2001
From: Stefan Metzmacher <metze@samba.org>
Date: Fri, 25 Nov 2022 13:13:36 +0100
Subject: [PATCH 22/30] CVE-2022-38023 s4:rpc_server/netlogon: debug 'reject
md5 servers' and 'allow nt4 crypto' misconfigurations
This allows the admin to notice what's wrong in order to adjust the
configuration if required.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15240
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
(cherry picked from commit 43df4be35950f491864ae8ada05d51b42a556381)
Conflict: NA
Reference: https://attachments.samba.org/attachment.cgi?id=17692
---
source4/rpc_server/netlogon/dcerpc_netlogon.c | 143 ++++++++++++++++++
1 file changed, 143 insertions(+)
diff --git a/source4/rpc_server/netlogon/dcerpc_netlogon.c b/source4/rpc_server/netlogon/dcerpc_netlogon.c
index a6e4499d5add..ec5807ef22af 100644
--- a/source4/rpc_server/netlogon/dcerpc_netlogon.c
+++ b/source4/rpc_server/netlogon/dcerpc_netlogon.c
@@ -64,10 +64,34 @@ static NTSTATUS dcesrv_interface_netlogon_bind(struct dcesrv_connection_context
const struct dcesrv_interface *iface)
{
struct loadparm_context *lp_ctx = context->conn->dce_ctx->lp_ctx;
+ bool global_allow_nt4_crypto = lpcfg_allow_nt4_crypto(lp_ctx);
+ bool global_reject_md5_client = lpcfg_reject_md5_clients(lp_ctx);
int schannel = lpcfg_server_schannel(lp_ctx);
bool schannel_global_required = (schannel == true);
+ static bool warned_global_nt4_once = false;
+ static bool warned_global_md5_once = false;
static bool warned_global_schannel_once = false;
+ if (global_allow_nt4_crypto && !warned_global_nt4_once) {
+ /*
+ * We want admins to notice their misconfiguration!
+ */
+ D_ERR("CVE-2022-38023 (and others): "
+ "Please configure 'allow nt4 crypto = no' (the default), "
+ "See https://bugzilla.samba.org/show_bug.cgi?id=15240\n");
+ warned_global_nt4_once = true;
+ }
+
+ if (!global_reject_md5_client && !warned_global_md5_once) {
+ /*
+ * We want admins to notice their misconfiguration!
+ */
+ D_ERR("CVE-2022-38023: "
+ "Please configure 'reject md5 clients = yes' (the default), "
+ "See https://bugzilla.samba.org/show_bug.cgi?id=15240\n");
+ warned_global_md5_once = true;
+ }
+
if (!schannel_global_required && !warned_global_schannel_once) {
/*
* We want admins to notice their misconfiguration!
@@ -143,6 +167,12 @@ static NTSTATUS dcesrv_netr_ServerAuthenticate3_check_downgrade(
bool reject_des_client;
bool allow_nt4_crypto;
bool reject_md5_client;
+ bool need_des = true;
+ bool need_md5 = true;
+ int CVE_2022_38023_warn_level = lpcfg_parm_int(lp_ctx, NULL,
+ "CVE_2022_38023", "warn_about_unused_debug_level", DBGLVL_ERR);
+ int CVE_2022_38023_error_level = lpcfg_parm_int(lp_ctx, NULL,
+ "CVE_2022_38023", "error_debug_level", DBGLVL_ERR);
/*
* We don't use lpcfg_parm_bool(), as we
@@ -183,19 +213,84 @@ static NTSTATUS dcesrv_netr_ServerAuthenticate3_check_downgrade(
}
if (negotiate_flags & NETLOGON_NEG_STRONG_KEYS) {
+ need_des = false;
reject_des_client = false;
}
if (negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
+ need_des = false;
+ need_md5 = false;
reject_des_client = false;
reject_md5_client = false;
}
if (reject_des_client || reject_md5_client) {
+ TALLOC_CTX *frame = talloc_stackframe();
+
+ if (lpcfg_weak_crypto(lp_ctx) == SAMBA_WEAK_CRYPTO_DISALLOWED) {
+ if (CVE_2022_38023_error_level < DBGLVL_NOTICE) {
+ CVE_2022_38023_error_level = DBGLVL_NOTICE;
+ }
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: "
+ "client_account[%s] computer_name[%s] "
+ "schannel_type[%u] "
+ "client_negotiate_flags[0x%x] "
+ "%s%s%s "
+ "NT_STATUS_DOWNGRADE_DETECTED "
+ "WEAK_CRYPTO_DISALLOWED\n",
+ log_escape(frame, r->in.account_name),
+ log_escape(frame, r->in.computer_name),
+ r->in.secure_channel_type,
+ (unsigned)*r->in.negotiate_flags,
+ trust_account_in_db ? "real_account[" : "",
+ trust_account_in_db ? trust_account_in_db : "",
+ trust_account_in_db ? "]" : ""));
+ goto return_downgrade;
+ }
+
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: "
+ "client_account[%s] computer_name[%s] "
+ "schannel_type[%u] "
+ "client_negotiate_flags[0x%x] "
+ "%s%s%s "
+ "NT_STATUS_DOWNGRADE_DETECTED "
+ "reject_des[%u] reject_md5[%u]\n",
+ log_escape(frame, r->in.account_name),
+ log_escape(frame, r->in.computer_name),
+ r->in.secure_channel_type,
+ (unsigned)*r->in.negotiate_flags,
+ trust_account_in_db ? "real_account[" : "",
+ trust_account_in_db ? trust_account_in_db : "",
+ trust_account_in_db ? "]" : "",
+ reject_des_client,
+ reject_md5_client));
+ if (trust_account_in_db == NULL) {
+ goto return_downgrade;
+ }
+
+ if (reject_md5_client && explicit_md5_opt == NULL) {
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: Check if option "
+ "'server reject md5 schannel:%s = no' "
+ "might be needed for a legacy client.\n",
+ trust_account_in_db));
+ }
+ if (reject_des_client && explicit_nt4_opt == NULL) {
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: Check if option "
+ "'allow nt4 crypto:%s = yes' "
+ "might be needed for a legacy client.\n",
+ trust_account_in_db));
+ }
+
+return_downgrade:
/*
* Here we match Windows 2012 and return no flags.
*/
*r->out.negotiate_flags = 0;
+ TALLOC_FREE(frame);
return NT_STATUS_DOWNGRADE_DETECTED;
}
@@ -228,6 +323,54 @@ static NTSTATUS dcesrv_netr_ServerAuthenticate3_check_downgrade(
*/
*r->out.negotiate_flags = negotiate_flags;
+ if (!NT_STATUS_IS_OK(orig_status) || trust_account_in_db == NULL) {
+ return orig_status;
+ }
+
+ if (global_reject_md5_client && account_reject_md5_client && explicit_md5_opt) {
+ D_INFO("CVE-2022-38023: Check if option "
+ "'server reject md5 schannel:%s = yes' not needed!?\n",
+ trust_account_in_db);
+ } else if (need_md5 && !account_reject_md5_client && explicit_md5_opt) {
+ D_INFO("CVE-2022-38023: Check if option "
+ "'server reject md5 schannel:%s = no' "
+ "still needed for a legacy client.\n",
+ trust_account_in_db);
+ } else if (need_md5 && explicit_md5_opt == NULL) {
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: Check if option "
+ "'server reject md5 schannel:%s = no' "
+ "might be needed for a legacy client.\n",
+ trust_account_in_db));
+ } else if (!account_reject_md5_client && explicit_md5_opt) {
+ DEBUG(CVE_2022_38023_warn_level, (
+ "CVE-2022-38023: Check if option "
+ "'server reject md5 schannel:%s = no' not needed!?\n",
+ trust_account_in_db));
+ }
+
+ if (!global_allow_nt4_crypto && !account_allow_nt4_crypto && explicit_nt4_opt) {
+ D_INFO("CVE-2022-38023: Check if option "
+ "'allow nt4 crypto:%s = no' not needed!?\n",
+ trust_account_in_db);
+ } else if (need_des && account_allow_nt4_crypto && explicit_nt4_opt) {
+ D_INFO("CVE-2022-38023: Check if option "
+ "'allow nt4 crypto:%s = yes' "
+ "still needed for a legacy client.\n",
+ trust_account_in_db);
+ } else if (need_des && explicit_nt4_opt == NULL) {
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: Check if option "
+ "'allow nt4 crypto:%s = yes' "
+ "might be needed for a legacy client.\n",
+ trust_account_in_db));
+ } else if (account_allow_nt4_crypto && explicit_nt4_opt) {
+ DEBUG(CVE_2022_38023_warn_level, (
+ "CVE-2022-38023: Check if option "
+ "'allow nt4 crypto:%s = yes' not needed!?\n",
+ trust_account_in_db));
+ }
+
return orig_status;
}
--
2.34.1
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