snort_dcerpc.c

snort2.8.4版本

/*
 * snort_dcerpc.c
 *
 * Copyright (C) 2004-2008 Sourcefire,Inc
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License Version 2 as
 * published by the Free Software Foundation.  You may not use, modify or
 * distribute this program under any other version of the GNU General
 * Public License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Description:
 *
 * This performs the DCERPC decoding.
 *
 * Arguments:
 *   
 * Effect:
 *
 * None
 *
 * NOTES:
 * - 08.12.04:  Initial Development.  SAS
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdlib.h>
#include <string.h>
#include <pcap.h>

#include "debug.h"
#include "snort_dcerpc.h"
#include "smb_structs.h"
#include "smb_andx_decode.h"
#include "smb_file_decode.h"
#include "dcerpc.h"
#include "dcerpc_util.h"
#include "bounds.h"
#include "sf_snort_packet.h"
#include "sf_types.h"

#include "profiler.h"
#ifdef PERF_PROFILING
extern PreprocStats dcerpcPerfStats;
extern PreprocStats dcerpcDetectPerfStats;
extern PreprocStats dcerpcIgnorePerfStats;
#endif

extern char SMBPorts[MAX_PORT_INDEX];
extern char DCERPCPorts[MAX_PORT_INDEX];
extern u_int8_t _debug_print;

extern u_int8_t _autodetect;
extern int _reassemble_increment;

extern u_int32_t _memcap;
extern u_int8_t _alert_memcap;
extern u_int8_t _disable_smb_fragmentation;
extern u_int8_t _disable_dcerpc_fragmentation;

u_int32_t _total_memory = 0;

#ifdef TARGET_BASED
DCERPC_ProtoIds _dce_proto_ids;
#endif

/* Session structure */
DCERPC    *_dcerpc;
/* Save packet so we don't have to pass it around */
SFSnortPacket *_dcerpc_pkt;

u_int8_t *dce_reassembly_buf = NULL;
const u_int16_t dce_reassembly_buf_size = IP_MAXPKT - (IP_HDR_LEN + TCP_HDR_LEN);

/* this is used to store one of the below */
SFSnortPacket *real_dce_mock_pkt = NULL;

SFSnortPacket *dce_mock_pkt = NULL;
const u_int16_t dce_mock_pkt_payload_len = IP_MAXPKT - (IP_HDR_LEN + TCP_HDR_LEN);
#ifdef SUP_IP6
SFSnortPacket *dce_mock_pkt_6 = NULL;
const u_int16_t dce_mock_pkt_6_payload_len = IP_MAXPKT - (IP6_HDR_LEN + TCP_HDR_LEN);
#endif

static DCERPC_TransType DCERPC_AutoDetect(SFSnortPacket *, const u_int8_t *, u_int16_t);
static void DCERPC_DataFree(DCERPC *);
static int ProcessRawDCERPC(SFSnortPacket *, const u_int8_t *, u_int16_t);
static int ProcessRawSMB(SFSnortPacket *, const u_int8_t *, u_int16_t);
static DCERPC_TransType DCERPC_GetTransport(SFSnortPacket *, char *);

void DCERPC_BufferReassemble(DCERPC_Buffer *sbuf)
{
    u_int16_t len;
    int status;

    if (DCERPC_BufferIsEmpty(sbuf))
        return;

    len = sbuf->len;

    /* Copy data into buffer */
    if (len > dce_reassembly_buf_size)
        len = dce_reassembly_buf_size;

    status = SafeMemcpy(dce_reassembly_buf, sbuf->data, len,
                        dce_reassembly_buf, dce_reassembly_buf + dce_reassembly_buf_size);

    if (status != SAFEMEM_SUCCESS)
    {
        DEBUG_WRAP(DebugMessage(DEBUG_DCERPC, "Failed to copy DCERPC data, "
                                "skipping DCERPC reassembly.\n"););
        return;
    }

    if (_debug_print)
    {
        PrintBuffer("DCE/RPC reassembled fragment",
                    (u_int8_t *)dce_reassembly_buf, (u_int16_t)len);
    }

    /* create pseudo packet */
    real_dce_mock_pkt = DCERPC_SetPseudoPacket(_dcerpc_pkt, dce_reassembly_buf, len);
}

void DCERPC_EarlyFragReassemble(DCERPC *dce_ssn_data, const u_int8_t *smb_hdr,
                                u_int16_t smb_hdr_len, u_int16_t opnum)
{
    dce_ssn_data->num_inc_reass++;
    if (_reassemble_increment == dce_ssn_data->num_inc_reass)
    {
        dce_ssn_data->num_inc_reass = 0;

        if (!DCERPC_BufferIsEmpty(&dce_ssn_data->dce_frag_buf))
        {
            DCERPC_REQ fake_req;

            memset(&fake_req, 0, sizeof(DCERPC_REQ));

            fake_req.dcerpc_hdr.version = 5;
            fake_req.dcerpc_hdr.flags = 0x03;
            fake_req.dcerpc_hdr.byte_order = 0x10;
            fake_req.opnum = opnum;

            /* Create a reassembly packet but don't free buffers */
            ReassembleDCERPCRequest(smb_hdr, smb_hdr_len, (uint8_t *)&fake_req);
        }
    }
}

void * DCERPC_GetReassemblyPkt(void)
{
    if (real_dce_mock_pkt != NULL)
        return (void *)real_dce_mock_pkt;

    return NULL;
}
 
SFSnortPacket * DCERPC_SetPseudoPacket(SFSnortPacket *p, const u_int8_t *data, u_int16_t data_len)
{
    SFSnortPacket *ret_pkt = dce_mock_pkt;
    u_int16_t payload_len = dce_mock_pkt_payload_len;
    u_int16_t ip_len;
    int result;

#ifdef SUP_IP6
    if (p->family == AF_INET)
    {
        IP_COPY_VALUE(ret_pkt->inner_ip4h.ip_src, (&p->ip4h->ip_src));
        IP_COPY_VALUE(ret_pkt->inner_ip4h.ip_dst, (&p->ip4h->ip_dst));

        //((IPV4Header *)ret_pkt->ip4h)->source.s_addr = p->ip4h->ip_src.ip32[0];
        //((IPV4Header *)ret_pkt->ip4h)->destination.s_addr = p->ip4h->ip_dst.ip32[0];
    }
    else
    {
        ret_pkt = dce_mock_pkt_6;

        IP_COPY_VALUE(ret_pkt->inner_ip6h.ip_src, (&p->ip6h->ip_src));
        IP_COPY_VALUE(ret_pkt->inner_ip6h.ip_dst, (&p->ip6h->ip_dst));

        payload_len = dce_mock_pkt_6_payload_len;
    }

    ret_pkt->family = p->family;

#else
    ((IPV4Header *)ret_pkt->ip4_header)->source.s_addr = p->ip4_header->source.s_addr;
    ((IPV4Header *)ret_pkt->ip4_header)->destination.s_addr = p->ip4_header->destination.s_addr;
#endif

    ((TCPHeader *)ret_pkt->tcp_header)->source_port = p->tcp_header->source_port;
    ((TCPHeader *)ret_pkt->tcp_header)->destination_port = p->tcp_header->destination_port;
    ret_pkt->src_port = p->src_port;
    ret_pkt->dst_port = p->dst_port;

    if(p->ether_header != NULL)
    {
        result = SafeMemcpy((void *)((EtherHeader *)ret_pkt->ether_header)->ether_source,
                            (void *)p->ether_header->ether_source,
                            (size_t)6,
                            (void *)ret_pkt->ether_header->ether_source,
                            (void *)((u_int8_t *)ret_pkt->ether_header->ether_source + 6));

        if (result != SAFEMEM_SUCCESS)
            return NULL;

        result = SafeMemcpy((void *)((EtherHeader *)ret_pkt->ether_header)->ether_destination,
                            (void *)p->ether_header->ether_destination,
                            (size_t)6,
                            (void *)ret_pkt->ether_header->ether_destination,
                            (void *)((u_int8_t *)ret_pkt->ether_header->ether_destination + 6));

        if (result != SAFEMEM_SUCCESS)
            return NULL;
    }

    if (data_len > payload_len)
        data_len = payload_len;

    result = SafeMemcpy((void *)ret_pkt->payload, (void *)data, (size_t)data_len,
                        (void *)ret_pkt->payload,
                        (void *)((u_int8_t *)ret_pkt->payload + payload_len));

    if (result != SAFEMEM_SUCCESS)
        return NULL;

    ret_pkt->payload_size = data_len;

    ((struct pcap_pkthdr *)ret_pkt->pcap_header)->caplen =
        ret_pkt->payload_size + IP_HDR_LEN + TCP_HDR_LEN + ETHER_HDR_LEN;
    ((struct pcap_pkthdr *)ret_pkt->pcap_header)->len = ret_pkt->pcap_header->caplen;
    ((struct pcap_pkthdr *)ret_pkt->pcap_header)->ts.tv_sec = p->pcap_header->ts.tv_sec;
    ((struct pcap_pkthdr *)ret_pkt->pcap_header)->ts.tv_usec = p->pcap_header->ts.tv_usec;

    ip_len = (u_int16_t)(ret_pkt->payload_size + IP_HDR_LEN + TCP_HDR_LEN);
#ifdef SUP_IP6
    if (p->family == AF_INET)
    {
        ret_pkt->ip4h->ip_len = ((IPV4Header *)ret_pkt->ip4_header)->data_length = htons(ip_len);
    }
    else
    {
        ip_len = (u_int16_t)(ret_pkt->payload_size + IP6_HDR_LEN + TCP_HDR_LEN);
        ret_pkt->ip6h->len = htons(ip_len);
    }
#else
    ((IPV4Header *)ret_pkt->ip4_header)->data_length = htons(ip_len);
#endif

    ret_pkt->flags = FLAG_STREAM_EST;
    ret_pkt->flags |= FLAG_FROM_CLIENT;
    ret_pkt->flags |= FLAG_DCE_RPKT;
    ret_pkt->stream_session_ptr = p->stream_session_ptr;

    /* Set bit in wire packet to indicate a reassembled packet needs to
     * be detected upon */
    _dpd.setPreprocGetReassemblyPktBit(_dcerpc_pkt, PP_DCERPC);

    return ret_pkt;
}

void DCERPC_InitPacket(void)
{
    /* Alloc for global reassembly buffers */
    dce_reassembly_buf = (u_int8_t *)calloc(1, dce_reassembly_buf_size);
    if (dce_reassembly_buf == NULL)
    {
        DynamicPreprocessorFatalMessage("Failed to allocate memory for "
                                        "reassembly packet\n");
    }

    /* Alloc for mock packets */
    dce_mock_pkt = (SFSnortPacket *)calloc(1, sizeof(SFSnortPacket));
    if (dce_mock_pkt == NULL)
    {
        DynamicPreprocessorFatalMessage("Failed to allocate memory for "
                                        "mock packet\n");
    }

    dce_mock_pkt->pcap_header = calloc(1, sizeof(struct pcap_pkthdr) +
                                             ETHER_HDR_LEN +
                                             SUN_SPARC_TWIDDLE + IP_MAXPKT);
    if (dce_mock_pkt->pcap_header == NULL)
    {
        DynamicPreprocessorFatalMessage("Failed to allocate memory "
                                        "for mock pcap header\n");
    }

    dce_mock_pkt->pkt_data =
        ((u_int8_t *)dce_mock_pkt->pcap_header) + sizeof(struct pcap_pkthdr);
    dce_mock_pkt->ether_header = 
        (void *)((u_int8_t *)dce_mock_pkt->pkt_data + SUN_SPARC_TWIDDLE);
    dce_mock_pkt->ip4_header =
        (IPV4Header *)((u_int8_t *)dce_mock_pkt->ether_header + ETHER_HDR_LEN);
    dce_mock_pkt->tcp_header =
        (TCPHeader *)((u_int8_t *)dce_mock_pkt->ip4_header + IP_HDR_LEN);

    dce_mock_pkt->payload = (u_int8_t *)dce_mock_pkt->tcp_header + TCP_HDR_LEN;

    ((EtherHeader *)dce_mock_pkt->ether_header)->ethernet_type = htons(0x0800);
    SET_IP4_VER((IPV4Header *)dce_mock_pkt->ip4_header, 0x4);
    SET_IP4_HLEN((IPV4Header *)dce_mock_pkt->ip4_header, 0x5);
    ((IPV4Header *)dce_mock_pkt->ip4_header)->proto = IPPROTO_TCP;
    ((IPV4Header *)dce_mock_pkt->ip4_header)->time_to_live = 0xF0;
    ((IPV4Header *)dce_mock_pkt->ip4_header)->type_service = 0x10;

    SET_TCP_HDR_OFFSET((TCPHeader *)dce_mock_pkt->tcp_header, 0x5);