detect-http-cookie.c

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/* Copyright (C) 2007-2018 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * 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
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

/**
 * \ingroup httplayer
 *
 * @{
 */


/**
 * \file
 *
 * \author Gurvinder Singh <gurvindersinghdahiya@gmail.com>
 *
 * Implements the http_cookie keyword
 */

#include "suricata-common.h"
#include "threads.h"
#include "debug.h"
#include "decode.h"
#include "detect.h"

#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
#include "detect-engine-prefilter.h"
#include "detect-content.h"
#include "detect-pcre.h"

#include "flow.h"
#include "flow-var.h"
#include "flow-util.h"

#include "util-debug.h"
#include "util-error.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
#include "util-spm.h"
#include "util-print.h"

#include "app-layer.h"
#include "app-layer-parser.h"

#include "app-layer-htp.h"
#include "detect-http-cookie.h"
#include "stream-tcp.h"

static int DetectHttpCookieSetup (DetectEngineCtx *, Signature *, const char *);
static int DetectHttpCookieSetupSticky (DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectHttpCookieRegisterTests(void);
#endif
static int g_http_cookie_buffer_id = 0;

static InspectionBuffer *GetRequestData(DetectEngineThreadCtx *det_ctx,
        const DetectEngineTransforms *transforms,
        Flow *_f, const uint8_t _flow_flags,
        void *txv, const int list_id);
static InspectionBuffer *GetResponseData(DetectEngineThreadCtx *det_ctx,
        const DetectEngineTransforms *transforms,
        Flow *_f, const uint8_t _flow_flags,
        void *txv, const int list_id);

/**
 * \brief Registration function for keyword: http_cookie
 */
void DetectHttpCookieRegister(void)
{
    /* http_cookie content modifier */
    sigmatch_table[DETECT_AL_HTTP_COOKIE].name = "http_cookie";
    sigmatch_table[DETECT_AL_HTTP_COOKIE].desc = "content modifier to match only on the HTTP cookie-buffer";
    sigmatch_table[DETECT_AL_HTTP_COOKIE].url = DOC_URL DOC_VERSION "/rules/http-keywords.html#http-cookie";
    sigmatch_table[DETECT_AL_HTTP_COOKIE].Setup = DetectHttpCookieSetup;
#ifdef UNITTESTS
    sigmatch_table[DETECT_AL_HTTP_COOKIE].RegisterTests = DetectHttpCookieRegisterTests;
#endif
    sigmatch_table[DETECT_AL_HTTP_COOKIE].flags |= SIGMATCH_NOOPT;
    sigmatch_table[DETECT_AL_HTTP_COOKIE].flags |= SIGMATCH_INFO_CONTENT_MODIFIER;
    sigmatch_table[DETECT_AL_HTTP_COOKIE].alternative = DETECT_HTTP_COOKIE;

    /* http.cookie sticky buffer */
    sigmatch_table[DETECT_HTTP_COOKIE].name = "http.cookie";
    sigmatch_table[DETECT_HTTP_COOKIE].desc = "sticky buffer to match on the HTTP Cookie/Set-Cookie buffers";
    sigmatch_table[DETECT_HTTP_COOKIE].url = DOC_URL DOC_VERSION "/rules/http-keywords.html#http-cookie";
    sigmatch_table[DETECT_HTTP_COOKIE].Setup = DetectHttpCookieSetupSticky;
    sigmatch_table[DETECT_HTTP_COOKIE].flags |= SIGMATCH_NOOPT;
    sigmatch_table[DETECT_HTTP_COOKIE].flags |= SIGMATCH_INFO_STICKY_BUFFER;

    DetectAppLayerInspectEngineRegister2("http_cookie", ALPROTO_HTTP,
            SIG_FLAG_TOSERVER, HTP_REQUEST_HEADERS,
            DetectEngineInspectBufferGeneric, GetRequestData);
    DetectAppLayerInspectEngineRegister2("http_cookie", ALPROTO_HTTP,
            SIG_FLAG_TOCLIENT, HTP_REQUEST_HEADERS,
            DetectEngineInspectBufferGeneric, GetResponseData);

    DetectAppLayerMpmRegister2("http_cookie", SIG_FLAG_TOSERVER, 2,
            PrefilterGenericMpmRegister, GetRequestData, ALPROTO_HTTP,
            HTP_REQUEST_HEADERS);
    DetectAppLayerMpmRegister2("http_cookie", SIG_FLAG_TOCLIENT, 2,
            PrefilterGenericMpmRegister, GetResponseData, ALPROTO_HTTP,
            HTP_REQUEST_HEADERS);

    DetectBufferTypeSetDescriptionByName("http_cookie",
            "http cookie header");

    g_http_cookie_buffer_id = DetectBufferTypeGetByName("http_cookie");
}

/**
 * \brief this function setups the http_cookie modifier keyword used in the rule
 *
 * \param de_ctx   Pointer to the Detection Engine Context
 * \param s        Pointer to the Signature to which the current keyword belongs
 * \param str      Should hold an empty string always
 *
 * \retval  0 On success
 * \retval -1 On failure
 */

static int DetectHttpCookieSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
{
    return DetectEngineContentModifierBufferSetup(de_ctx, s, str,
                                                  DETECT_AL_HTTP_COOKIE,
                                                  g_http_cookie_buffer_id,
                                                  ALPROTO_HTTP);
}

/**
 * \brief this function setup the http.user_agent keyword used in the rule
 *
 * \param de_ctx   Pointer to the Detection Engine Context
 * \param s        Pointer to the Signature to which the current keyword belongs
 * \param str      Should hold an empty string always
 *
 * \retval 0       On success
 */
static int DetectHttpCookieSetupSticky(DetectEngineCtx *de_ctx, Signature *s, const char *str)
{
    DetectBufferSetActiveList(s, g_http_cookie_buffer_id);
    s->alproto = ALPROTO_HTTP;
    return 0;
}

static InspectionBuffer *GetRequestData(DetectEngineThreadCtx *det_ctx,
        const DetectEngineTransforms *transforms, Flow *_f,
        const uint8_t _flow_flags, void *txv, const int list_id)
{
    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
    if (buffer->inspect == NULL) {
        htp_tx_t *tx = (htp_tx_t *)txv;

        if (tx->request_headers == NULL)
            return NULL;

        htp_header_t *h = (htp_header_t *)htp_table_get_c(tx->request_headers,
                "Cookie");
        if (h == NULL || h->value == NULL) {
            SCLogDebug("HTTP cookie header not present in this request");
            return NULL;
        }

        const uint32_t data_len = bstr_len(h->value);
        const uint8_t *data = bstr_ptr(h->value);

        InspectionBufferSetup(buffer, data, data_len);
        InspectionBufferApplyTransforms(buffer, transforms);
    }

    return buffer;
}

static InspectionBuffer *GetResponseData(DetectEngineThreadCtx *det_ctx,
        const DetectEngineTransforms *transforms, Flow *_f,
        const uint8_t _flow_flags, void *txv, const int list_id)
{
    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
    if (buffer->inspect == NULL) {
        htp_tx_t *tx = (htp_tx_t *)txv;

        if (tx->response_headers == NULL)
            return NULL;

        htp_header_t *h = (htp_header_t *)htp_table_get_c(tx->response_headers,
                "Set-Cookie");
        if (h == NULL || h->value == NULL) {
            SCLogDebug("HTTP cookie header not present in this request");
            return NULL;
        }

        const uint32_t data_len = bstr_len(h->value);
        const uint8_t *data = bstr_ptr(h->value);

        InspectionBufferSetup(buffer, data, data_len);
        InspectionBufferApplyTransforms(buffer, transforms);
    }

    return buffer;
}

/******************************** UNITESTS **********************************/

#ifdef UNITTESTS
#include "tests/detect-http-cookie.c"
#endif /* UNITTESTS */

/**
 * @}
 */