snort_stream5_udp.c

Snort为国际上著名的轻量型入侵防御系统,为国内多家著名“自主知识产权”网络安全公司所使用。

#include "debug.h"
#include "detect.h"
#include "plugbase.h"
#include "mstring.h"
#include "sfxhash.h"
#include "util.h"
#include "decode.h"

#include "stream5_common.h"
#include "stream_api.h"
#include "snort_stream5_session.h"
#include "stream_ignore.h"

#include "plugin_enum.h"
#include "rules.h"
#include "snort.h"

#include "dynamic-plugins/sp_dynamic.h"

#include "profiler.h"
#ifdef PERF_PROFILING
PreprocStats s5UdpPerfStats;
#endif

/*  M A C R O S  **************************************************/
/* actions */
#define ACTION_NOTHING                  0x00000000

/*  D A T A  S T R U C T U R E S  ***********************************/
typedef struct _UdpSession
{
    Stream5LWSession *lwSsn;

    u_int32_t   sender_ip;
    u_int16_t   sender_port;
    u_int32_t   responder_ip;
    u_int16_t   responder_port;

    struct timeval ssn_time;

    //u_int8_t    c_ttl;
    //u_int8_t    s_ttl;

    u_int32_t   expire_time;
} UdpSession;

typedef struct _Stream5UdpPolicy
{
    u_int32_t   session_timeout;
    u_int16_t   flags;
    IpAddrSet   *bound_addrs;
} Stream5UdpPolicy;

/* Mark specific ports as "to inspect" */
#define UDP_INSPECT 0x01
#define UDP_SESSION 0x02
static u_int16_t udp_ports[65536];

/*  G L O B A L S  **************************************************/
static Stream5SessionCache *udp_lws_cache;
static Stream5UdpPolicy **udpPolicyList = NULL; /* List of Policies configured */
static u_int8_t numUdpPolicies = 0;
static MemPool udp_session_mempool;

/*  P R O T O T Y P E S  ********************************************/
static void Stream5ParseUdpArgs(u_char *, Stream5UdpPolicy *);
static void Stream5PrintUdpConfig(Stream5UdpPolicy *);
void UdpSessionCleanup(Stream5LWSession *ssn);
static int ProcessUdp(Stream5LWSession *, Packet *, Stream5UdpPolicy *);

void Stream5InitUdp()
{
    /* Now UDP */ 
    if((udp_lws_cache == NULL) && s5_global_config.track_udp_sessions)
    {
        udp_lws_cache = InitLWSessionCache(s5_global_config.max_udp_sessions,
                30, 5, 0, &UdpSessionCleanup);

        if(!udp_lws_cache)
        {
            LogMessage("Unable to init stream5 UDP session cache, no UDP "
                       "stream inspection!\n");
            s5_global_config.track_udp_sessions = 0;
            s5_global_config.max_udp_sessions = 0;
            return;
        }
        mempool_init(&udp_session_mempool, s5_global_config.max_udp_sessions, sizeof(UdpSession));
    }
}

void Stream5UdpPolicyInit(u_char *args)
{
    Stream5UdpPolicy *s5UdpPolicy;
    s5UdpPolicy = (Stream5UdpPolicy *) SnortAlloc(sizeof(Stream5UdpPolicy));
    s5UdpPolicy->bound_addrs = (IpAddrSet *) SnortAlloc(sizeof(IpAddrSet));

    Stream5ParseUdpArgs(args, s5UdpPolicy);

    /* Now add this context to the internal list */
    if (udpPolicyList == NULL)
    {
        numUdpPolicies = 1;
        udpPolicyList = (Stream5UdpPolicy **)SnortAlloc(sizeof (Stream5UdpPolicy *)
            * numUdpPolicies);
    }
    else
    {
        Stream5UdpPolicy **tmpPolicyList =
            (Stream5UdpPolicy **)SnortAlloc(sizeof (Stream5UdpPolicy *)
            * (++numUdpPolicies));
        memcpy(tmpPolicyList, udpPolicyList,
            sizeof(Stream5UdpPolicy *) * (numUdpPolicies-1));
        free(udpPolicyList);
        
        udpPolicyList = tmpPolicyList;
    }
    udpPolicyList[numUdpPolicies-1] = s5UdpPolicy;

    Stream5PrintUdpConfig(s5UdpPolicy);

    return;
}

static void Stream5ParseUdpArgs(u_char *args, Stream5UdpPolicy *s5UdpPolicy)
{
    char **toks;
    int num_toks;
    int i;
    char *index;
    char **stoks = NULL;
    int s_toks;
    char *endPtr;

    s5UdpPolicy->session_timeout = S5_DEFAULT_SSN_TIMEOUT;
    s5UdpPolicy->flags = 0;

    if(args != NULL && strlen(args) != 0)
    {
        toks = mSplit(args, ",", 6, &num_toks, 0);

        i=0;

        while(i < num_toks)
        {
            index = toks[i];

            while(isspace((int)*index)) index++;

            stoks = mSplit(index, " ", 2, &s_toks, 0);

            if(!strcasecmp(stoks[0], "timeout"))
            {
                if(stoks[1])
                {
                    s5UdpPolicy->session_timeout = strtoul(stoks[1], &endPtr, 10);
                }
                
                if (!stoks[1] || (endPtr == &stoks[1][0]))
                {
                    FatalError("%s(%d) => Invalid timeout in config file.  Integer parameter required.\n",
                            file_name, file_line);
                }
            }
            else if (!strcasecmp(stoks[0], "ignore_any_rules"))
            {
                s5UdpPolicy->flags |= STREAM5_CONFIG_IGNORE_ANY;
            }
            else
            {
                FatalError("%s(%d) => Invalid Stream5 UDP Policy option\n", 
                            file_name, file_line);
            }

            mSplitFree(&stoks, s_toks);
            i++;
        }

        mSplitFree(&toks, num_toks);

        if(s5UdpPolicy->bound_addrs == NULL)
        {
            /* allocate and initializes the
             * IpAddrSet at the same time
             * set to "any"
             */
            s5UdpPolicy->bound_addrs = (IpAddrSet *) SnortAlloc(sizeof(IpAddrSet));
        }
    }
    return;
}

static void Stream5PrintUdpConfig(Stream5UdpPolicy *s5UdpPolicy)
{
    LogMessage("Stream5 UDP Policy config:\n");
    LogMessage("    Timeout: %d seconds\n", s5UdpPolicy->session_timeout);
    LogMessage("    Flags: 0x%X\n", s5UdpPolicy->flags);
    IpAddrSetPrint("    Bound Addresses:", s5UdpPolicy->bound_addrs);
}

int Stream5VerifyUdpConfig()
{
    int16_t sport, dport;
    RuleListNode *rule;
    RuleTreeNode *rtn;
    OptTreeNode *otn;
    extern RuleListNode *RuleLists;
    char inspectSrc, inspectDst;

    if (!udp_lws_cache)
        return -1;

    if (numUdpPolicies < 1)
        return -1;

    /* Post-process UDP rules to establish UDP ports to inspect. */
    for (rule=RuleLists; rule; rule=rule->next)
    {
        if(!rule->RuleList)
            continue;

        /*
        **  Get UDP rules
        */
        if(rule->RuleList->UdpList)
        {
            for(rtn = rule->RuleList->UdpList; rtn != NULL; rtn = rtn->right)
            {
                inspectSrc = inspectDst = 0;

                sport = (rtn->hsp == rtn->lsp) ? rtn->hsp : -1;

                if (rtn->flags & ANY_SRC_PORT)
                {
                    sport = -1;
                }

                if (sport > 0 &&  rtn->not_sp_flag > 0 )
                {
                    sport = -1;
                }

                /* Set the source port to inspect */
                if (sport != -1)
                {
                    inspectSrc = 1;
                    udp_ports[sport] |= UDP_INSPECT;
                }

                dport = (rtn->hdp == rtn->ldp) ? rtn->hdp : -1;

                if (rtn->flags & ANY_DST_PORT)
                {
                    dport = -1;
                }

                if (dport > 0 && rtn->not_dp_flag > 0 )
                {
                    dport = -1;
                }

                /* Set the dest port to inspect */
                if (dport != -1)
                {
                    inspectDst = 1;
                    udp_ports[dport] |= UDP_INSPECT;
                }

                if (inspectSrc || inspectDst)
                {
                    /* Look for an OTN with flow or flowbits keyword */
                    for (otn = rtn->down; otn; otn = otn->next)
                    {
                        if (otn->ds_list[PLUGIN_CLIENTSERVER] ||
                            otn->ds_list[PLUGIN_FLOWBIT])
                        {
                            if (inspectSrc)
                            {
                                udp_ports[sport] |= UDP_SESSION;
                            }
                            if (inspectDst)
                            {
                                udp_ports[dport] |= UDP_SESSION;
                            }
                        }
#ifdef DYNAMIC_PLUGIN
                        else if (DynamicHasFlow(otn) ||
                                 DynamicHasFlowbit(otn))
                        {
                            if (inspectSrc)
                            {
                                udp_ports[sport] |= UDP_SESSION;
                            }
                            if (inspectDst)
                            {
                                udp_ports[dport] |= UDP_SESSION;
                            }
                        }
#endif
                    }
                }
            }
        }
    }

    return 0;
}

#ifdef DEBUG
static void PrintUdpSession(UdpSession *us)
{
    LogMessage("UdpSession:\n");
    LogMessage("    ssn_time:           %lu\n", us->ssn_time.tv_sec);
    LogMessage("    sender IP:          0x%08X\n", us->sender_ip);
    LogMessage("    responder IP:          0x%08X\n", us->responder_ip);
    LogMessage("    sender port:        %d\n", us->sender_port);
    LogMessage("    responder port:        %d\n", us->responder_port);

    LogMessage("    flags:              0x%X\n", us->lwSsn->session_flags);
}
#endif

Stream5LWSession *GetLWUdpSession(SessionKey *key)
{
    return GetLWSessionFromKey(udp_lws_cache, key);
}

void UdpSessionCleanup(Stream5LWSession *ssn)
{
    UdpSession *udpssn = NULL;

    if (ssn->proto_specific_data)
        udpssn = (UdpSession *)ssn->proto_specific_data->data;