From 10f485b3a27e10906aa6ee40833fca8bf81b5511 Mon Sep 17 00:00:00 2001

From: Stefan Metzmacher <metze@samba.org>

Date: Sat, 22 Jan 2022 01:08:26 +0100

Subject: [PATCH] dcesrv_core: wrap gensec_*() calls in [un]become_root() calls

This is important for the source3/rpc_server code as it might

be called embedded in smbd and may not run as root with access

to our private tdb/ldb files.

Note this is only really needed for 4.15 and older, as

we no longer run the rpc_server embedded in smbd,

but we better be consistent for now.

This should be able to fix the problem the printing no longer works

on Windows 7 with 2021-10 monthly rollup patch (KB5006743).

Windows uses NTLMSSP with privacy at the DCERPC layer on top

of NCACN_NP (smb).

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14867

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

Reviewed-by: Andreas Schneider <asn@samba.org>

(cherry picked from commit 0651fa474cd68b18d8eb9bdc7c4ba5b847ba9ad9)

---

 librpc/rpc/dcesrv_auth.c         |  5 +++++

 librpc/rpc/dcesrv_core.c         | 18 ++++++++++++++++++

 librpc/rpc/dcesrv_core.h         |  2 ++

 source3/rpc_server/rpc_config.c  |  2 ++

 source4/rpc_server/service_rpc.c | 10 ++++++++++

 5 files changed, 37 insertions(+)

diff --git a/librpc/rpc/dcesrv_auth.c b/librpc/rpc/dcesrv_auth.c

index fec8df513a83..99d8e0162160 100644

--- a/librpc/rpc/dcesrv_auth.c

+++ b/librpc/rpc/dcesrv_auth.c

@@ -130,11 +130,13 @@ static bool dcesrv_auth_prepare_gensec(struct dcesrv_call_state *call)

 	auth->auth_level = call->in_auth_info.auth_level;

 	auth->auth_context_id = call->in_auth_info.auth_context_id;

+	cb->auth.become_root();

 	status = cb->auth.gensec_prepare(

 		auth,

 		call,

 		&auth->gensec_security,

 		cb->auth.private_data);

+	cb->auth.unbecome_root();

 	if (!NT_STATUS_IS_OK(status)) {

 		DEBUG(1, ("Failed to call samba_server_gensec_start %s\n",

 			  nt_errstr(status)));

@@ -329,6 +331,7 @@ bool dcesrv_auth_bind(struct dcesrv_call_state *call)

 NTSTATUS dcesrv_auth_complete(struct dcesrv_call_state *call, NTSTATUS status)

 {

 	struct dcesrv_auth *auth = call->auth_state;

+	struct dcesrv_context_callbacks *cb = call->conn->dce_ctx->callbacks;

 	const char *pdu = "<unknown>";

 	switch (call->pkt.ptype) {

@@ -359,9 +362,11 @@ NTSTATUS dcesrv_auth_complete(struct dcesrv_call_state *call, NTSTATUS status)

 		return status;

 	}

+	cb->auth.become_root();

 	status = gensec_session_info(auth->gensec_security,

 				     auth,

 				     &auth->session_info);

+	cb->auth.unbecome_root();

 	if (!NT_STATUS_IS_OK(status)) {

 		DEBUG(1, ("Failed to establish session_info: %s\n",

 			  nt_errstr(status)));

diff --git a/librpc/rpc/dcesrv_core.c b/librpc/rpc/dcesrv_core.c

index d16159b0b6cd..ea91fc689b4a 100644

--- a/librpc/rpc/dcesrv_core.c

+++ b/librpc/rpc/dcesrv_core.c

@@ -938,6 +938,7 @@ static NTSTATUS dcesrv_bind(struct dcesrv_call_state *call)

 	struct dcerpc_binding *ep_2nd_description = NULL;

 	const char *endpoint = NULL;

 	struct dcesrv_auth *auth = call->auth_state;

+	struct dcesrv_context_callbacks *cb = call->conn->dce_ctx->callbacks;

 	struct dcerpc_ack_ctx *ack_ctx_list = NULL;

 	struct dcerpc_ack_ctx *ack_features = NULL;

 	struct tevent_req *subreq = NULL;

@@ -1143,9 +1144,11 @@ static NTSTATUS dcesrv_bind(struct dcesrv_call_state *call)

 		return dcesrv_auth_reply(call);

 	}

+	cb->auth.become_root();

 	subreq = gensec_update_send(call, call->event_ctx,

 				    auth->gensec_security,

 				    call->in_auth_info.credentials);

+	cb->auth.unbecome_root();

 	if (subreq == NULL) {

 		return NT_STATUS_NO_MEMORY;

 	}

@@ -1160,10 +1163,13 @@ static void dcesrv_bind_done(struct tevent_req *subreq)

 		tevent_req_callback_data(subreq,

 		struct dcesrv_call_state);

 	struct dcesrv_connection *conn = call->conn;

+	struct dcesrv_context_callbacks *cb = call->conn->dce_ctx->callbacks;

 	NTSTATUS status;

+	cb->auth.become_root();

 	status = gensec_update_recv(subreq, call,

 				    &call->out_auth_info->credentials);

+	cb->auth.unbecome_root();

 	TALLOC_FREE(subreq);

 	status = dcesrv_auth_complete(call, status);

@@ -1221,6 +1227,7 @@ static NTSTATUS dcesrv_auth3(struct dcesrv_call_state *call)

 {

 	struct dcesrv_connection *conn = call->conn;

 	struct dcesrv_auth *auth = call->auth_state;

+	struct dcesrv_context_callbacks *cb = call->conn->dce_ctx->callbacks;

 	struct tevent_req *subreq = NULL;

 	NTSTATUS status;

@@ -1265,9 +1272,11 @@ static NTSTATUS dcesrv_auth3(struct dcesrv_call_state *call)

 		return NT_STATUS_OK;

 	}

+	cb->auth.become_root();

 	subreq = gensec_update_send(call, call->event_ctx,

 				    auth->gensec_security,

 				    call->in_auth_info.credentials);

+	cb->auth.unbecome_root();

 	if (subreq == NULL) {

 		return NT_STATUS_NO_MEMORY;

 	}

@@ -1283,10 +1292,13 @@ static void dcesrv_auth3_done(struct tevent_req *subreq)

 		struct dcesrv_call_state);

 	struct dcesrv_connection *conn = call->conn;

 	struct dcesrv_auth *auth = call->auth_state;

+	struct dcesrv_context_callbacks *cb = call->conn->dce_ctx->callbacks;

 	NTSTATUS status;

+	cb->auth.become_root();

 	status = gensec_update_recv(subreq, call,

 				    &call->out_auth_info->credentials);

+	cb->auth.unbecome_root();

 	TALLOC_FREE(subreq);

 	status = dcesrv_auth_complete(call, status);

@@ -1555,6 +1567,7 @@ static NTSTATUS dcesrv_alter(struct dcesrv_call_state *call)

 	struct ncacn_packet *pkt = &call->ack_pkt;

 	uint32_t extra_flags = 0;

 	struct dcesrv_auth *auth = call->auth_state;

+	struct dcesrv_context_callbacks *cb = call->conn->dce_ctx->callbacks;

 	struct dcerpc_ack_ctx *ack_ctx_list = NULL;

 	struct tevent_req *subreq = NULL;

 	size_t i;

@@ -1666,9 +1679,11 @@ static NTSTATUS dcesrv_alter(struct dcesrv_call_state *call)

 		return dcesrv_auth_reply(call);

 	}

+	cb->auth.become_root();

 	subreq = gensec_update_send(call, call->event_ctx,

 				    auth->gensec_security,

 				    call->in_auth_info.credentials);

+	cb->auth.unbecome_root();

 	if (subreq == NULL) {

 		return NT_STATUS_NO_MEMORY;

 	}

@@ -1683,10 +1698,13 @@ static void dcesrv_alter_done(struct tevent_req *subreq)

 		tevent_req_callback_data(subreq,

 		struct dcesrv_call_state);

 	struct dcesrv_connection *conn = call->conn;

+	struct dcesrv_context_callbacks *cb = call->conn->dce_ctx->callbacks;

 	NTSTATUS status;

+	cb->auth.become_root();

 	status = gensec_update_recv(subreq, call,

 				    &call->out_auth_info->credentials);

+	cb->auth.unbecome_root();

 	TALLOC_FREE(subreq);

 	status = dcesrv_auth_complete(call, status);

diff --git a/librpc/rpc/dcesrv_core.h b/librpc/rpc/dcesrv_core.h

index d8d5f9030959..0538442e0ce6 100644

--- a/librpc/rpc/dcesrv_core.h

+++ b/librpc/rpc/dcesrv_core.h

@@ -392,6 +392,8 @@ struct dcesrv_context_callbacks {

 			struct gensec_security **out,

 			void *private_data);

 		void *private_data;

+		void (*become_root)(void);

+		void (*unbecome_root)(void);

 	} auth;

 	struct {

 		NTSTATUS (*find)(

diff --git a/source3/rpc_server/rpc_config.c b/source3/rpc_server/rpc_config.c

index 2f1a01da1c0b..289c4f398409 100644

--- a/source3/rpc_server/rpc_config.c

+++ b/source3/rpc_server/rpc_config.c

@@ -31,6 +31,8 @@

 static struct dcesrv_context_callbacks srv_callbacks = {

 	.log.successful_authz = dcesrv_log_successful_authz,

 	.auth.gensec_prepare = dcesrv_auth_gensec_prepare,

+	.auth.become_root = become_root,

+	.auth.unbecome_root = unbecome_root,

 	.assoc_group.find = dcesrv_assoc_group_find,

 };

diff --git a/source4/rpc_server/service_rpc.c b/source4/rpc_server/service_rpc.c

index d8c6746d7815..ebb50f8a7ef3 100644

--- a/source4/rpc_server/service_rpc.c

+++ b/source4/rpc_server/service_rpc.c

@@ -40,9 +40,19 @@

 #include "../libcli/named_pipe_auth/npa_tstream.h"

 #include "samba/process_model.h"

+static void skip_become_root(void)

+{

+}

+

+static void skip_unbecome_root(void)

+{

+}

+

 static struct dcesrv_context_callbacks srv_callbacks = {

 	.log.successful_authz = log_successful_dcesrv_authz_event,

 	.auth.gensec_prepare = dcesrv_gensec_prepare,

+	.auth.become_root = skip_become_root,

+	.auth.unbecome_root = skip_unbecome_root,

 	.assoc_group.find = dcesrv_assoc_group_find,

 };

-- 

2.25.1