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samba/backport-0028-CVE-2022-38023.patch

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From a19b425cccd935c77cf15f3123ed2611fc30cea6 Mon Sep 17 00:00:00 2001
From: Stefan Metzmacher <metze@samba.org>
Date: Fri, 25 Nov 2022 14:05:30 +0100
Subject: [PATCH 28/30] CVE-2022-38023 s4:rpc_server/netlogon: implement
"server schannel require seal[:COMPUTERACCOUNT]"
By default we'll now require schannel connections with
privacy/sealing/encryption.
But we allow exceptions for specific computer/trust accounts.
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 b3ed90a0541a271a7c6d4bee1201fa47adc3c0c1)
Conflict: NA
Reference: https://attachments.samba.org/attachment.cgi?id=17692
---
selftest/target/Samba4.pm | 28 ++
source4/rpc_server/netlogon/dcerpc_netlogon.c | 244 +++++++++++++++++-
2 files changed, 271 insertions(+), 1 deletion(-)
diff --git a/selftest/target/Samba4.pm b/selftest/target/Samba4.pm
index 3328cf617225..5c83bcbd4038 100755
--- a/selftest/target/Samba4.pm
+++ b/selftest/target/Samba4.pm
@@ -1646,9 +1646,23 @@ sub provision_ad_dc_ntvfs($$$)
server require schannel:schannel10\$ = no
server require schannel:schannel11\$ = no
server require schannel:torturetest\$ = no
+ server schannel require seal:schannel0\$ = no
+ server schannel require seal:schannel1\$ = no
+ server schannel require seal:schannel2\$ = no
+ server schannel require seal:schannel3\$ = no
+ server schannel require seal:schannel4\$ = no
+ server schannel require seal:schannel5\$ = no
+ server schannel require seal:schannel6\$ = no
+ server schannel require seal:schannel7\$ = no
+ server schannel require seal:schannel8\$ = no
+ server schannel require seal:schannel9\$ = no
+ server schannel require seal:schannel10\$ = no
+ server schannel require seal:schannel11\$ = no
+ server schannel require seal:torturetest\$ = no
# needed for 'samba.tests.auth_log' tests
server require schannel:LOCALDC\$ = no
+ server schannel require seal:LOCALDC\$ = no
";
push (@{$extra_provision_options}, "--use-ntvfs");
my $ret = $self->provision($prefix,
@@ -2050,6 +2064,19 @@ sub provision_ad_dc($$$$$$$)
server require schannel:schannel10\$ = no
server require schannel:schannel11\$ = no
server require schannel:torturetest\$ = no
+ server schannel require seal:schannel0\$ = no
+ server schannel require seal:schannel1\$ = no
+ server schannel require seal:schannel2\$ = no
+ server schannel require seal:schannel3\$ = no
+ server schannel require seal:schannel4\$ = no
+ server schannel require seal:schannel5\$ = no
+ server schannel require seal:schannel6\$ = no
+ server schannel require seal:schannel7\$ = no
+ server schannel require seal:schannel8\$ = no
+ server schannel require seal:schannel9\$ = no
+ server schannel require seal:schannel10\$ = no
+ server schannel require seal:schannel11\$ = no
+ server schannel require seal:torturetest\$ = no
auth event notification = true
dsdb event notification = true
@@ -2743,6 +2770,7 @@ sub setup_ad_dc_smb1
# needed for 'samba.tests.auth_log' tests
server require schannel:ADDCSMB1\$ = no
+ server schannel require seal:ADDCSMB1\$ = no
";
return _setup_ad_dc($self, $path, $conf_opts, "addcsmb1", "addom2.samba.example.com");
}
diff --git a/source4/rpc_server/netlogon/dcerpc_netlogon.c b/source4/rpc_server/netlogon/dcerpc_netlogon.c
index 45dcec133fb3..aa24a539abfd 100644
--- a/source4/rpc_server/netlogon/dcerpc_netlogon.c
+++ b/source4/rpc_server/netlogon/dcerpc_netlogon.c
@@ -68,9 +68,11 @@ static NTSTATUS dcesrv_interface_netlogon_bind(struct dcesrv_connection_context
bool global_reject_md5_client = lpcfg_reject_md5_clients(lp_ctx);
int schannel = lpcfg_server_schannel(lp_ctx);
bool schannel_global_required = (schannel == true);
+ bool global_require_seal = lpcfg_server_schannel_require_seal(lp_ctx);
static bool warned_global_nt4_once = false;
static bool warned_global_md5_once = false;
static bool warned_global_schannel_once = false;
+ static bool warned_global_seal_once = false;
if (global_allow_nt4_crypto && !warned_global_nt4_once) {
/*
@@ -102,6 +104,16 @@ static NTSTATUS dcesrv_interface_netlogon_bind(struct dcesrv_connection_context
warned_global_schannel_once = true;
}
+ if (!global_require_seal && !warned_global_seal_once) {
+ /*
+ * We want admins to notice their misconfiguration!
+ */
+ D_ERR("CVE-2022-38023 (and others): "
+ "Please configure 'server schannel require seal = yes' (the default), "
+ "See https://bugzilla.samba.org/show_bug.cgi?id=15240\n");
+ warned_global_seal_once = true;
+ }
+
return dcesrv_interface_bind_reject_connect(context, iface);
}
@@ -886,6 +898,10 @@ struct dcesrv_netr_check_schannel_state {
bool schannel_required;
bool schannel_explicitly_set;
+ bool seal_global_required;
+ bool seal_required;
+ bool seal_explicitly_set;
+
NTSTATUS result;
};
@@ -900,6 +916,9 @@ static NTSTATUS dcesrv_netr_check_schannel_get_state(struct dcesrv_call_state *d
bool schannel_global_required = (schannel == true);
bool schannel_required = schannel_global_required;
const char *explicit_opt = NULL;
+ bool global_require_seal = lpcfg_server_schannel_require_seal(lp_ctx);
+ bool require_seal = global_require_seal;
+ const char *explicit_seal_opt = NULL;
#define DCESRV_NETR_CHECK_SCHANNEL_STATE_MAGIC (NETLOGON_SERVER_PIPE_STATE_MAGIC+1)
struct dcesrv_netr_check_schannel_state *s = NULL;
NTSTATUS status;
@@ -937,6 +956,19 @@ new_state:
s->auth_level = auth_level;
s->result = NT_STATUS_MORE_PROCESSING_REQUIRED;
+ /*
+ * We don't use lpcfg_parm_bool(), as we
+ * need the explicit_opt pointer in order to
+ * adjust the debug messages.
+ */
+ explicit_seal_opt = lpcfg_get_parametric(lp_ctx,
+ NULL,
+ "server schannel require seal",
+ creds->account_name);
+ if (explicit_seal_opt != NULL) {
+ require_seal = lp_bool(explicit_seal_opt);
+ }
+
/*
* We don't use lpcfg_parm_bool(), as we
* need the explicit_opt pointer in order to
@@ -954,6 +986,10 @@ new_state:
s->schannel_required = schannel_required;
s->schannel_explicitly_set = explicit_opt != NULL;
+ s->seal_global_required = global_require_seal;
+ s->seal_required = require_seal;
+ s->seal_explicitly_set = explicit_seal_opt != NULL;
+
status = dcesrv_iface_state_store_conn(dce_call,
DCESRV_NETR_CHECK_SCHANNEL_STATE_MAGIC,
s);
@@ -975,6 +1011,10 @@ static NTSTATUS dcesrv_netr_check_schannel_once(struct dcesrv_call_state *dce_ca
"CVE_2020_1472", "warn_about_unused_debug_level", DBGLVL_ERR);
int CVE_2020_1472_error_level = lpcfg_parm_int(lp_ctx, NULL,
"CVE_2020_1472", "error_debug_level", DBGLVL_ERR);
+ 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);
TALLOC_CTX *frame = talloc_stackframe();
unsigned int dbg_lvl = DBGLVL_DEBUG;
const char *opname = "<unknown>";
@@ -1004,18 +1044,107 @@ static NTSTATUS dcesrv_netr_check_schannel_once(struct dcesrv_call_state *dce_ca
}
DEBUG(dbg_lvl, (
- "CVE-2020-1472(ZeroLogon): "
+ "CVE-2020-1472(ZeroLogon)/CVE-2022-38023: "
+ "%s request (opnum[%u]) %s schannel from "
+ "client_account[%s] client_computer_name[%s] %s\n",
+ opname, opnum, reason,
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name),
+ nt_errstr(s->result)));
+ TALLOC_FREE(frame);
+ return s->result;
+ }
+
+ if (s->auth_type == DCERPC_AUTH_TYPE_SCHANNEL &&
+ s->auth_level == DCERPC_AUTH_LEVEL_PRIVACY)
+ {
+ s->result = NT_STATUS_OK;
+
+ if (s->schannel_explicitly_set && !s->schannel_required) {
+ dbg_lvl = MIN(dbg_lvl, CVE_2020_1472_warn_level);
+ } else if (!s->schannel_required) {
+ dbg_lvl = MIN(dbg_lvl, DBGLVL_INFO);
+ }
+ if (s->seal_explicitly_set && !s->seal_required) {
+ dbg_lvl = MIN(dbg_lvl, CVE_2022_38023_warn_level);
+ } else if (!s->seal_required) {
+ dbg_lvl = MIN(dbg_lvl, DBGLVL_INFO);
+ }
+
+ DEBUG(dbg_lvl, (
+ "CVE-2020-1472(ZeroLogon)/CVE-2022-38023: "
"%s request (opnum[%u]) %s schannel from "
"client_account[%s] client_computer_name[%s] %s\n",
opname, opnum, reason,
log_escape(frame, creds->account_name),
log_escape(frame, creds->computer_name),
nt_errstr(s->result)));
+
+ if (s->schannel_explicitly_set && !s->schannel_required) {
+ DEBUG(CVE_2020_1472_warn_level, (
+ "CVE-2020-1472(ZeroLogon): "
+ "Option 'server require schannel:%s = no' not needed for '%s'!\n",
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name)));
+ }
+
+ if (s->seal_explicitly_set && !s->seal_required) {
+ DEBUG(CVE_2022_38023_warn_level, (
+ "CVE-2022-38023: "
+ "Option 'server schannel require seal:%s = no' not needed for '%s'!\n",
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name)));
+ }
+
TALLOC_FREE(frame);
return s->result;
}
if (s->auth_type == DCERPC_AUTH_TYPE_SCHANNEL) {
+ if (s->seal_required) {
+ s->result = NT_STATUS_ACCESS_DENIED;
+
+ if (s->seal_explicitly_set) {
+ dbg_lvl = DBGLVL_NOTICE;
+ } else {
+ dbg_lvl = MIN(dbg_lvl, CVE_2022_38023_error_level);
+ }
+ if (s->schannel_explicitly_set && !s->schannel_required) {
+ dbg_lvl = MIN(dbg_lvl, CVE_2022_38023_warn_level);
+ }
+
+ DEBUG(dbg_lvl, (
+ "CVE-2022-38023: "
+ "%s request (opnum[%u]) %s schannel from "
+ "from client_account[%s] client_computer_name[%s] %s\n",
+ opname, opnum, reason,
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name),
+ nt_errstr(s->result)));
+ if (s->seal_explicitly_set) {
+ D_NOTICE("CVE-2022-38023: Option "
+ "'server schannel require seal:%s = yes' "
+ "rejects access for client.\n",
+ log_escape(frame, creds->account_name));
+ } else {
+ DEBUG(CVE_2020_1472_error_level, (
+ "CVE-2022-38023: Check if option "
+ "'server schannel require seal:%s = no' "
+ "might be needed for a legacy client.\n",
+ log_escape(frame, creds->account_name)));
+ }
+ if (s->schannel_explicitly_set && !s->schannel_required) {
+ DEBUG(CVE_2020_1472_warn_level, (
+ "CVE-2020-1472(ZeroLogon): Option "
+ "'server require schannel:%s = no' "
+ "not needed for '%s'!\n",
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name)));
+ }
+ TALLOC_FREE(frame);
+ return s->result;
+ }
+
s->result = NT_STATUS_OK;
if (s->schannel_explicitly_set && !s->schannel_required) {
@@ -1023,6 +1152,11 @@ static NTSTATUS dcesrv_netr_check_schannel_once(struct dcesrv_call_state *dce_ca
} else if (!s->schannel_required) {
dbg_lvl = MIN(dbg_lvl, DBGLVL_INFO);
}
+ if (s->seal_explicitly_set && !s->seal_required) {
+ dbg_lvl = MIN(dbg_lvl, DBGLVL_INFO);
+ } else if (!s->seal_required) {
+ dbg_lvl = MIN(dbg_lvl, CVE_2022_38023_error_level);
+ }
DEBUG(dbg_lvl, (
"CVE-2020-1472(ZeroLogon): "
@@ -1039,7 +1173,77 @@ static NTSTATUS dcesrv_netr_check_schannel_once(struct dcesrv_call_state *dce_ca
log_escape(frame, creds->account_name),
log_escape(frame, creds->computer_name)));
}
+ if (s->seal_explicitly_set && !s->seal_required) {
+ D_INFO("CVE-2022-38023: "
+ "Option 'server schannel require seal:%s = no' still needed for '%s'!\n",
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name));
+ } else if (!s->seal_required) {
+ /*
+ * admins should set
+ * server schannel require seal:COMPUTER$ = no
+ * in order to avoid the level 0 messages.
+ * Over time they can switch the global value
+ * to be strict.
+ */
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: "
+ "Please use 'server schannel require seal:%s = no' "
+ "for '%s' to avoid this warning!\n",
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name)));
+ }
+
+ TALLOC_FREE(frame);
+ return s->result;
+ }
+
+ if (s->seal_required) {
+ s->result = NT_STATUS_ACCESS_DENIED;
+
+ if (s->seal_explicitly_set) {
+ dbg_lvl = MIN(dbg_lvl, DBGLVL_NOTICE);
+ } else {
+ dbg_lvl = MIN(dbg_lvl, CVE_2022_38023_error_level);
+ }
+ if (!s->schannel_explicitly_set) {
+ dbg_lvl = MIN(dbg_lvl, CVE_2020_1472_error_level);
+ } else if (s->schannel_required) {
+ dbg_lvl = MIN(dbg_lvl, DBGLVL_NOTICE);
+ }
+ DEBUG(dbg_lvl, (
+ "CVE-2020-1472(ZeroLogon)/CVE-2022-38023: "
+ "%s request (opnum[%u]) %s schannel from "
+ "from client_account[%s] client_computer_name[%s] %s\n",
+ opname, opnum, reason,
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name),
+ nt_errstr(s->result)));
+ if (s->seal_explicitly_set) {
+ D_NOTICE("CVE-2022-38023: Option "
+ "'server schannel require seal:%s = yes' "
+ "rejects access for client.\n",
+ log_escape(frame, creds->account_name));
+ } else {
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: Check if option "
+ "'server schannel require seal:%s = no' "
+ "might be needed for a legacy client.\n",
+ log_escape(frame, creds->account_name)));
+ }
+ if (!s->schannel_explicitly_set) {
+ DEBUG(CVE_2020_1472_error_level, (
+ "CVE-2020-1472(ZeroLogon): Check if option "
+ "'server require schannel:%s = no' "
+ "might be needed for a legacy client.\n",
+ log_escape(frame, creds->account_name)));
+ } else if (s->schannel_required) {
+ D_NOTICE("CVE-2022-38023: Option "
+ "'server require schannel:%s = yes' "
+ "also rejects access for client.\n",
+ log_escape(frame, creds->account_name));
+ }
TALLOC_FREE(frame);
return s->result;
}
@@ -1052,6 +1256,9 @@ static NTSTATUS dcesrv_netr_check_schannel_once(struct dcesrv_call_state *dce_ca
} else {
dbg_lvl = MIN(dbg_lvl, CVE_2020_1472_error_level);
}
+ if (!s->seal_explicitly_set) {
+ dbg_lvl = MIN(dbg_lvl, CVE_2022_38023_error_level);
+ }
DEBUG(dbg_lvl, (
"CVE-2020-1472(ZeroLogon)/CVE-2022-38023: "
@@ -1073,12 +1280,25 @@ static NTSTATUS dcesrv_netr_check_schannel_once(struct dcesrv_call_state *dce_ca
"might be needed for a legacy client.\n",
log_escape(frame, creds->account_name)));
}
+ if (!s->seal_explicitly_set) {
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: Check if option "
+ "'server schannel require seal:%s = no' "
+ "might be needed for a legacy client.\n",
+ log_escape(frame, creds->account_name)));
+ }
TALLOC_FREE(frame);
return s->result;
}
s->result = NT_STATUS_OK;
+ if (s->seal_explicitly_set) {
+ dbg_lvl = MIN(dbg_lvl, DBGLVL_INFO);
+ } else {
+ dbg_lvl = MIN(dbg_lvl, CVE_2022_38023_error_level);
+ }
+
if (s->schannel_explicitly_set) {
dbg_lvl = MIN(dbg_lvl, DBGLVL_INFO);
} else {
@@ -1094,6 +1314,28 @@ static NTSTATUS dcesrv_netr_check_schannel_once(struct dcesrv_call_state *dce_ca
log_escape(frame, creds->computer_name),
nt_errstr(s->result)));
+ if (s->seal_explicitly_set) {
+ D_INFO("CVE-2022-38023: Option "
+ "'server schannel require seal:%s = no' "
+ "still needed for '%s'!\n",
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name));
+ } else {
+ /*
+ * admins should set
+ * server schannel require seal:COMPUTER$ = no
+ * in order to avoid the level 0 messages.
+ * Over time they can switch the global value
+ * to be strict.
+ */
+ DEBUG(CVE_2022_38023_error_level, (
+ "CVE-2022-38023: Please use "
+ "'server schannel require seal:%s = no' "
+ "for '%s' to avoid this warning!\n",
+ log_escape(frame, creds->account_name),
+ log_escape(frame, creds->computer_name)));
+ }
+
if (s->schannel_explicitly_set) {
D_INFO("CVE-2020-1472(ZeroLogon): Option "
"'server require schannel:%s = no' "
--
2.34.1
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