/* Copyright (C) 2007-2020 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.

 */

/**

 * \file   detect-ssl-version.c

 *

 * \author Gurvinder Singh <gurvindersinghdahiya@gmail.com>

 *

 * Implements the ssl_version keyword

 */

#include "suricata-common.h"

#include "threads.h"

#include "decode.h"

#include "detect.h"

#include "detect-parse.h"

#include "detect-engine.h"

#include "detect-engine-mpm.h"

#include "detect-engine-state.h"

#include "flow.h"

#include "flow-var.h"

#include "flow-util.h"

#include "util-debug.h"

#include "util-unittest.h"

#include "util-unittest-helper.h"

#include "app-layer.h"

#include "app-layer-parser.h"

#include "detect-ssl-version.h"

#include "stream-tcp.h"

#include "app-layer-ssl.h"

static int DetectSslVersionMatch(DetectEngineThreadCtx *,

        Flow *, uint8_t, void *, void *,

        const Signature *, const SigMatchCtx *);

static int DetectSslVersionSetup(DetectEngineCtx *, Signature *, const char *);

#ifdef UNITTESTS

static void DetectSslVersionRegisterTests(void);

#endif

static void DetectSslVersionFree(DetectEngineCtx *, void *);

static int g_tls_generic_list_id = 0;

/**

 * \brief Registration function for keyword: ssl_version

 */

void DetectSslVersionRegister(void)

{

    sigmatch_table[DETECT_AL_SSL_VERSION].name = "ssl_version";

    sigmatch_table[DETECT_AL_SSL_VERSION].desc = "match version of SSL/TLS record";

    sigmatch_table[DETECT_AL_SSL_VERSION].url = "/rules/tls-keywords.html#ssl-version";

    sigmatch_table[DETECT_AL_SSL_VERSION].AppLayerTxMatch = DetectSslVersionMatch;

    sigmatch_table[DETECT_AL_SSL_VERSION].Setup = DetectSslVersionSetup;

    sigmatch_table[DETECT_AL_SSL_VERSION].Free  = DetectSslVersionFree;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_SSL_VERSION].RegisterTests = DetectSslVersionRegisterTests;

#endif

    g_tls_generic_list_id = DetectBufferTypeRegister("tls_generic");

}

/**

 * \brief match the specified version on a ssl session

 *

 * \param t pointer to thread vars

 * \param det_ctx pointer to the pattern matcher thread

 * \param p pointer to the current packet

 * \param m pointer to the sigmatch that we will cast into DetectSslVersionData

 *

 * \retval 0 no match

 * \retval 1 match

 */

static int DetectSslVersionMatch(DetectEngineThreadCtx *det_ctx,

        Flow *f, uint8_t flags, void *state, void *txv,

        const Signature *s, const SigMatchCtx *m)

{

    SCEnter();

    int ret = 0;

    uint16_t ver = 0;

    uint8_t sig_ver = TLS_UNKNOWN;

    const DetectSslVersionData *ssl = (const DetectSslVersionData *)m;

    SSLState *app_state = (SSLState *)state;

    if (app_state == NULL) {

        SCLogDebug("no app state, no match");

        SCReturnInt(0);

    }

    if (flags & STREAM_TOCLIENT) {

        SCLogDebug("server (toclient) version is 0x%02X",

                   app_state->server_connp.version);

        ver = app_state->server_connp.version;

    } else if (flags & STREAM_TOSERVER) {

        SCLogDebug("client (toserver) version is 0x%02X",

                   app_state->client_connp.version);

        ver = app_state->client_connp.version;

    }

    switch (ver) {

        case SSL_VERSION_2:

            if (ver == ssl->data[SSLv2].ver)

                ret = 1;

            sig_ver = SSLv2;

            break;

        case SSL_VERSION_3:

            if (ver == ssl->data[SSLv3].ver)

                ret = 1;

            sig_ver = SSLv3;

            break;

        case TLS_VERSION_10:

            if (ver == ssl->data[TLS10].ver)

                ret = 1;

            sig_ver = TLS10;

            break;

        case TLS_VERSION_11:

            if (ver == ssl->data[TLS11].ver)

                ret = 1;

            sig_ver = TLS11;

            break;

        case TLS_VERSION_12:

            if (ver == ssl->data[TLS12].ver)

                ret = 1;

            sig_ver = TLS12;

            break;

        case TLS_VERSION_13_DRAFT28:

        case TLS_VERSION_13_DRAFT27:

        case TLS_VERSION_13_DRAFT26:

        case TLS_VERSION_13_DRAFT25:

        case TLS_VERSION_13_DRAFT24:

        case TLS_VERSION_13_DRAFT23:

        case TLS_VERSION_13_DRAFT22:

        case TLS_VERSION_13_DRAFT21:

        case TLS_VERSION_13_DRAFT20:

        case TLS_VERSION_13_DRAFT19:

        case TLS_VERSION_13_DRAFT18:

        case TLS_VERSION_13_DRAFT17:

        case TLS_VERSION_13_DRAFT16:

        case TLS_VERSION_13_PRE_DRAFT16:

            if (((ver >> 8) & 0xff) == 0x7f)

                ver = TLS_VERSION_13;

            /* fall through */

        case TLS_VERSION_13:

            if (ver == ssl->data[TLS13].ver)

                ret = 1;

            sig_ver = TLS13;

            break;

    }

    if (sig_ver == TLS_UNKNOWN)

        SCReturnInt(0);

    SCReturnInt(ret ^ ((ssl->data[sig_ver].flags & DETECT_SSL_VERSION_NEGATED) ? 1 : 0));

}

struct SSLVersionKeywords {

    const char *word;

    int index;

    uint16_t value;

};

struct SSLVersionKeywords ssl_version_keywords[TLS_SIZE] = {

    { "sslv2", SSLv2, SSL_VERSION_2 },

    { "sslv3", SSLv3, SSL_VERSION_3 },

    { "tls1.0", TLS10, TLS_VERSION_10 },

    { "tls1.1", TLS11, TLS_VERSION_11 },

    { "tls1.2", TLS12, TLS_VERSION_12 },

    { "tls1.3", TLS13, TLS_VERSION_13 },

};

/**

 * \brief This function is used to parse ssl_version data passed via

 *        keyword: "ssl_version"

 *

 * \param de_ctx Pointer to the detection engine context

 * \param str Pointer to the user provided options

 *

 * \retval ssl pointer to DetectSslVersionData on success

 * \retval NULL on failure

 */

static DetectSslVersionData *DetectSslVersionParse(DetectEngineCtx *de_ctx, const char *str)

{

    DetectSslVersionData *ssl = NULL;

    const char *tmp_str = str;

    size_t tmp_len = 0;

    uint8_t found = 0;

    /* We have a correct ssl_version options */

    ssl = SCCalloc(1, sizeof(DetectSslVersionData));

    if (unlikely(ssl == NULL))

        goto error;

    // skip leading space

    while (tmp_str[0] != 0 && isspace(tmp_str[0])) {

        tmp_str++;

    }

    if (tmp_str[0] == 0) {

        SCLogError("Invalid empty value");

        goto error;

    }

    // iterate every version separated by comma

    while (tmp_str[0] != 0) {

        uint8_t neg = 0;

        if (tmp_str[0] == '!') {

            neg = 1;

            tmp_str++;

        }

        // counts word length

        tmp_len = 0;

        while (tmp_str[tmp_len] != 0 && !isspace(tmp_str[tmp_len]) && tmp_str[tmp_len] != ',') {

            tmp_len++;

        }

        bool is_keyword = false;

        for (size_t i = 0; i < TLS_SIZE; i++) {

            if (tmp_len == strlen(ssl_version_keywords[i].word) &&

                    strncasecmp(ssl_version_keywords[i].word, tmp_str, tmp_len) == 0) {

                if (ssl->data[ssl_version_keywords[i].index].ver != 0) {

                    SCLogError("Invalid duplicate value");

                    goto error;

                }

                ssl->data[ssl_version_keywords[i].index].ver = ssl_version_keywords[i].value;

                if (neg == 1)

                    ssl->data[ssl_version_keywords[i].index].flags |= DETECT_SSL_VERSION_NEGATED;

                is_keyword = true;

                break;

            }

        }

        if (!is_keyword) {

            SCLogError("Invalid unknown value");

            goto error;

        }

        /* check consistency between negative and positive values :

         * if there is a negative value, it overrides positive values

         */

        if (found == 0) {

            found |= 1 << neg;

        } else if (found != 1 << neg) {

            SCLogError("Invalid value mixing negative and positive forms");

            goto error;

        }

        tmp_str += tmp_len;

        while (isspace(tmp_str[0]) || tmp_str[0] == ',') {

            tmp_str++;

        }

    }

    return ssl;

error:

    if (ssl != NULL)

        DetectSslVersionFree(de_ctx, ssl);

    return NULL;

}

/**

 * \brief this function is used to add the parsed "id" option

 * \brief into the current signature

 *

 * \param de_ctx pointer to the Detection Engine Context

 * \param s pointer to the Current Signature

 * \param idstr pointer to the user provided "id" option

 *

 * \retval 0 on Success

 * \retval -1 on Failure

 */

static int DetectSslVersionSetup (DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    DetectSslVersionData *ssl = NULL;

    SigMatch *sm = NULL;

    if (DetectSignatureSetAppProto(s, ALPROTO_TLS) != 0)

        return -1;

    ssl = DetectSslVersionParse(de_ctx, str);

    if (ssl == NULL)

        goto error;

    /* Okay so far so good, lets get this into a SigMatch

     * and put it in the Signature. */

    sm = SigMatchAlloc();

    if (sm == NULL)

        goto error;

    sm->type = DETECT_AL_SSL_VERSION;

    sm->ctx = (void *)ssl;

    SigMatchAppendSMToList(s, sm, g_tls_generic_list_id);

    return 0;

error:

    if (ssl != NULL)

        DetectSslVersionFree(de_ctx, ssl);

    if (sm != NULL)

        SCFree(sm);

    return -1;

}

/**

 * \brief this function will free memory associated with DetectSslVersionData

 *

 * \param id_d pointer to DetectSslVersionData

 */

void DetectSslVersionFree(DetectEngineCtx *de_ctx, void *ptr)

{

    if (ptr != NULL)

        SCFree(ptr);

}

#ifdef UNITTESTS

#include "tests/detect-ssl-version.c"

#endif