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dcesrv_core: introduce dcesrv_connection->transport_max_recv_frag

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The max fragment size depends on the transport.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14356

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
(cherry picked from commit 09e8dd23ce)
This commit is contained in:
Stefan Metzmacher 2020-11-12 16:38:32 +01:00 committed by Jule Anger
parent 71aad11c2c
commit fd6e9855c3
3 changed files with 35 additions and 5 deletions
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38
librpc/rpc/dcesrv_core.c
View File

@ -36,6 +36,7 @@
#include "system/network.h"
#include "lib/util/idtree_random.h"
#include "nsswitch/winbind_client.h"
#include "libcli/smb/tstream_smbXcli_np.h"
/**
* @file
@ -676,6 +677,8 @@ _PUBLIC_ NTSTATUS dcesrv_endpoint_connect(struct dcesrv_context *dce_ctx,
{
struct dcesrv_auth *auth = NULL;
struct dcesrv_connection *p = NULL;
enum dcerpc_transport_t transport =
dcerpc_binding_get_transport(ep->ep_description);
if (!session_info) {
return NT_STATUS_ACCESS_DENIED;
@ -695,9 +698,21 @@ _PUBLIC_ NTSTATUS dcesrv_endpoint_connect(struct dcesrv_context *dce_ctx,
p->event_ctx = event_ctx;
p->state_flags = state_flags;
p->allow_bind = true;
p->max_recv_frag = 5840;
p->max_xmit_frag = 5840;
p->max_total_request_size = DCERPC_NCACN_REQUEST_DEFAULT_MAX_SIZE;
/*
* SMB uses 4280, while all others use 5480
* note that p->transport_max_recv_frag is fixed
* for the lifetime of the connection, it's not
* negotiated by bind.
*/
if (transport == NCACN_NP) {
p->transport_max_recv_frag = TSTREAM_SMBXCLI_NP_MAX_BUF_SIZE;
} else {
p->transport_max_recv_frag = DCERPC_FRAG_MAX_SIZE;
}
/* these might be overwritten by BIND */
p->max_recv_frag = p->transport_max_recv_frag;
p->max_xmit_frag = p->transport_max_recv_frag;
p->support_hdr_signing = lpcfg_parm_bool(dce_ctx->lp_ctx,
NULL,
@ -1116,12 +1131,20 @@ static NTSTATUS dcesrv_bind(struct dcesrv_call_state *call)
DCERPC_BIND_NAK_REASON_PROTOCOL_VERSION_NOT_SUPPORTED);
}
/*
* Note that BIND and ALTER allow frag_len up to UINT16_MAX,
* so we don't check again frag_len against
* call->conn->transport_max_recv_frag
*/
/* max_recv_frag and max_xmit_frag result always in the same value! */
max_req = MIN(call->pkt.u.bind.max_xmit_frag,
call->pkt.u.bind.max_recv_frag);
/*
* The values are between 2048 and 5840 tested against Windows 2012R2
* via ncacn_ip_tcp on port 135.
*
* call->conn->transport_max_recv_frag stays fixed at 5840 (4280 for SMB)
*/
max_req = MAX(2048, max_req);
max_rep = MIN(max_req, conn->max_recv_frag);
@ -1759,6 +1782,12 @@ static NTSTATUS dcesrv_alter(struct dcesrv_call_state *call)
return dcesrv_fault_disconnect(call, DCERPC_NCA_S_PROTO_ERROR);
}
/*
* Note that BIND and ALTER allow frag_len up to UINT16_MAX,
* so we don't check again frag_len against
* call->conn->transport_max_recv_frag
*/
auth_ok = dcesrv_auth_alter(call);
if (!auth_ok) {
if (call->fault_code != 0) {
@ -2318,14 +2347,15 @@ static NTSTATUS dcesrv_process_ncacn_packet(struct dcesrv_connection *dce_conn,
DCERPC_NCA_S_PROTO_ERROR);
}
if (call->pkt.frag_length > DCERPC_FRAG_MAX_SIZE) {
if (call->pkt.frag_length > call->conn->transport_max_recv_frag) {
/*
* We don't use dcesrv_fault_disconnect()
* here, because we don't want to set
* DCERPC_PFC_FLAG_DID_NOT_EXECUTE
*
* Note that we don't check against the negotiated
* max_recv_frag, but a hard coded value.
* max_recv_frag, but a hard coded value from
* the transport.
*/
return dcesrv_fault_disconnect0(call, DCERPC_NCA_S_PROTO_ERROR);
}

1
librpc/rpc/dcesrv_core.h
View File

@ -272,6 +272,7 @@ struct dcesrv_connection {
struct dcesrv_call_state *call_list;
/* the maximum size the client wants to receive */
uint16_t transport_max_recv_frag;
uint16_t max_recv_frag;
uint16_t max_xmit_frag;

1
selftest/knownfail.d/dcerpc-transport-xmit
View File

@ -1 +0,0 @@
^samba.tests.dcerpc.raw_protocol.samba.tests.dcerpc.raw_protocol.TestDCERPC_BIND.test_neg_xmit_ffff_ffff_smb