/* 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

 *

 * \author Pablo Rincon <pablo.rincon.crespo@gmail.com>

 *

 * Implements the ssh.protoversion keyword

 * You can specify a concrete version like ssh.protoversion: 1.66

 * or search for protoversion 2 compat (1.99 is considered as 2) like

 * ssh.protoversion:2_compat

 * or just the beginning of the string like ssh.protoversion:"1."

 */

#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 "detect-engine-build.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 "app-layer-ssh.h"

#include "detect-ssh-proto-version.h"

#include "rust.h"

#include "stream-tcp.h"

/**

 * \brief Regex for parsing the protoversion string

 */

#define PARSE_REGEX  "^\\s*\"?\\s*([0-9]+([\\.\\-0-9]+)?|2_compat)\\s*\"?\\s*$"

static DetectParseRegex parse_regex;

static int DetectSshVersionMatch (DetectEngineThreadCtx *,

        Flow *, uint8_t, void *, void *,

        const Signature *, const SigMatchCtx *);

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

#ifdef UNITTESTS

static void DetectSshVersionRegisterTests(void);

#endif

static void DetectSshVersionFree(DetectEngineCtx *, void *);

static int g_ssh_banner_list_id = 0;

/**

 * \brief Registration function for keyword: ssh.protoversion

 */

void DetectSshVersionRegister(void)

{

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].name = "ssh.protoversion";

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].desc = "match SSH protocol version";

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].url = "/rules/ssh-keywords.html#ssh-protoversion";

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].AppLayerTxMatch = DetectSshVersionMatch;

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].Setup = DetectSshVersionSetup;

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].Free  = DetectSshVersionFree;

#ifdef UNITTESTS

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].RegisterTests = DetectSshVersionRegisterTests;

#endif

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].flags = SIGMATCH_QUOTES_OPTIONAL|SIGMATCH_INFO_DEPRECATED;

    sigmatch_table[DETECT_AL_SSH_PROTOVERSION].alternative = DETECT_AL_SSH_PROTOCOL;

    DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);

    g_ssh_banner_list_id = DetectBufferTypeRegister("ssh_banner");

}

/**

 * \brief match the specified version on a ssh 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 DetectSshVersionData

 *

 * \retval 0 no match

 * \retval 1 match

 */

static int DetectSshVersionMatch (DetectEngineThreadCtx *det_ctx,

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

        const Signature *s, const SigMatchCtx *m)

{

    SCEnter();

    SCLogDebug("lets see");

    DetectSshVersionData *ssh = (DetectSshVersionData *)m;

    if (state == NULL) {

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

        SCReturnInt(0);

    }

    int ret = 0;

    const uint8_t *protocol = NULL;

    uint32_t b_len = 0;

    if (rs_ssh_tx_get_protocol(txv, &protocol, &b_len, flags) != 1)

        SCReturnInt(0);

    if (protocol == NULL || b_len == 0)

        SCReturnInt(0);

    if (ssh->flags & SSH_FLAG_PROTOVERSION_2_COMPAT) {

        SCLogDebug("looking for ssh protoversion 2 compat");

        if (protocol[0] == '2') {

            ret = 1;

        } else if (b_len >= 4) {

            if (memcmp(protocol, "1.99", 4) == 0)    {

                ret = 1;

            }

        }

    } else {

        SCLogDebug("looking for ssh protoversion %s length %"PRIu16"", ssh->ver, ssh->len);

        if (b_len == ssh->len) {

            if (memcmp(protocol, ssh->ver, ssh->len) == 0) {

                ret = 1;

            }

        }

    }

    SCReturnInt(ret);

}

/**

 * \brief This function is used to parse IPV4 ip_id passed via keyword: "id"

 *

 * \param de_ctx Pointer to the detection engine context

 * \param idstr Pointer to the user provided id option

 *

 * \retval id_d pointer to DetectSshVersionData on success

 * \retval NULL on failure

 */

static DetectSshVersionData *DetectSshVersionParse (DetectEngineCtx *de_ctx, const char *str)

{

    DetectSshVersionData *ssh = NULL;

    int res = 0;

    size_t pcre2_len;

    pcre2_match_data *match = NULL;

    int ret = DetectParsePcreExec(&parse_regex, &match, str, 0, 0);

    if (ret < 1 || ret > 3) {

        SCLogError("invalid ssh.protoversion option");

        goto error;

    }

    if (ret > 1) {

        const char *str_ptr;

        res = pcre2_substring_get_bynumber(match, 1, (PCRE2_UCHAR8 **)&str_ptr, &pcre2_len);

        if (res < 0) {

            SCLogError("pcre2_substring_get_bynumber failed");

            goto error;

        }

        /* We have a correct id option */

        ssh = SCMalloc(sizeof(DetectSshVersionData));

        if (unlikely(ssh == NULL)) {

            pcre2_substring_free((PCRE2_UCHAR *)str_ptr);

            goto error;

        }

        memset(ssh, 0x00, sizeof(DetectSshVersionData));

        /* If we expect a protocol version 2 or 1.99 (considered 2, we

         * will compare it with both strings) */

        if (strcmp("2_compat", str_ptr) == 0) {

            ssh->flags |= SSH_FLAG_PROTOVERSION_2_COMPAT;

            SCLogDebug("will look for ssh protocol version 2 (2, 2.0, 1.99 that's considered as 2");

            pcre2_substring_free((PCRE2_UCHAR *)str_ptr);

            return ssh;

        }

        ssh->ver = (uint8_t *)SCStrdup((char*)str_ptr);

        if (ssh->ver == NULL) {

            pcre2_substring_free((PCRE2_UCHAR *)str_ptr);

            goto error;

        }

        ssh->len = (uint16_t)strlen((char *)ssh->ver);

        pcre2_substring_free((PCRE2_UCHAR *)str_ptr);

        SCLogDebug("will look for ssh %s", ssh->ver);

    }

    pcre2_match_data_free(match);

    return ssh;

error:

    if (match) {

        pcre2_match_data_free(match);

    }

    if (ssh != NULL)

        DetectSshVersionFree(de_ctx, ssh);

    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 DetectSshVersionSetup (DetectEngineCtx *de_ctx, Signature *s, const char *str)

{

    DetectSshVersionData *ssh = NULL;

    SigMatch *sm = NULL;

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

        return -1;

    ssh = DetectSshVersionParse(de_ctx, str);

    if (ssh == 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_SSH_PROTOVERSION;

    sm->ctx = (void *)ssh;

    SigMatchAppendSMToList(s, sm, g_ssh_banner_list_id);

    return 0;

error:

    if (ssh != NULL)

        DetectSshVersionFree(de_ctx, ssh);

    if (sm != NULL)

        SCFree(sm);

    return -1;

}

/**

 * \brief this function will free memory associated with DetectSshVersionData

 *

 * \param id_d pointer to DetectSshVersionData

 */

void DetectSshVersionFree(DetectEngineCtx *de_ctx, void *ptr)

{

    DetectSshVersionData *sshd = (DetectSshVersionData *)ptr;

    SCFree(sshd->ver);

    SCFree(sshd);

}

#ifdef UNITTESTS /* UNITTESTS */

#include "detect-engine-alert.h"

/**

 * \test DetectSshVersionTestParse01 is a test to make sure that we parse

 *       a proto version correctly

 */

static int DetectSshVersionTestParse01 (void)

{

    DetectSshVersionData *ssh = NULL;

    ssh = DetectSshVersionParse(NULL, "1.0");

    FAIL_IF_NULL(ssh);

    FAIL_IF_NOT(strncmp((char *)ssh->ver, "1.0", 3) == 0);

    DetectSshVersionFree(NULL, ssh);

    PASS;

}

/**

 * \test DetectSshVersionTestParse02 is a test to make sure that we parse

 *       the proto version (compatible with proto version 2) correctly

 */

static int DetectSshVersionTestParse02 (void)

{

    DetectSshVersionData *ssh = NULL;

    ssh = DetectSshVersionParse(NULL, "2_compat");

    FAIL_IF_NOT(ssh->flags & SSH_FLAG_PROTOVERSION_2_COMPAT);

    DetectSshVersionFree(NULL, ssh);

    PASS;

}

/**

 * \test DetectSshVersionTestParse03 is a test to make sure that we

 *       don't return a ssh_data with an invalid value specified

 */

static int DetectSshVersionTestParse03 (void)

{

    DetectSshVersionData *ssh = NULL;

    ssh = DetectSshVersionParse(NULL, "2_com");

    FAIL_IF_NOT_NULL(ssh);

    ssh = DetectSshVersionParse(NULL, "");

    FAIL_IF_NOT_NULL(ssh);

    ssh = DetectSshVersionParse(NULL, ".1");

    FAIL_IF_NOT_NULL(ssh);

    ssh = DetectSshVersionParse(NULL, "lalala");

    FAIL_IF_NOT_NULL(ssh);

    PASS;

}

#include "stream-tcp-reassemble.h"

#include "stream-tcp-util.h"

/** \test Send a get request in three chunks + more data. */

static int DetectSshVersionTestDetect01(void)

{

    TcpReassemblyThreadCtx *ra_ctx = NULL;

    ThreadVars tv;

    TcpSession ssn;

    Flow *f = NULL;

    Packet *p = NULL;

    uint8_t sshbuf1[] = "SSH-1.";

    uint8_t sshbuf2[] = "10-PuTTY_2.123" ;

    uint8_t sshbuf3[] = "\n";

    uint8_t sshbuf4[] = "whatever...";

    uint8_t* sshbufs[4] = {sshbuf1, sshbuf2, sshbuf3, sshbuf4};

    uint32_t sshlens[4] = {sizeof(sshbuf1) - 1, sizeof(sshbuf2) - 1, sizeof(sshbuf3) - 1, sizeof(sshbuf4) - 1};

    memset(&tv, 0x00, sizeof(tv));

    StreamTcpUTInit(&ra_ctx);

    StreamTcpUTInitInline();

    StreamTcpUTSetupSession(&ssn);

    StreamTcpUTSetupStream(&ssn.server, 1);

    StreamTcpUTSetupStream(&ssn.client, 1);

    f = UTHBuildFlow(AF_INET, "1.1.1.1", "2.2.2.2", 1234, 2222);

    FAIL_IF_NULL(f);

    f->protoctx = &ssn;

    f->proto = IPPROTO_TCP;

    f->alproto = ALPROTO_SSH;

    p = UTHBuildPacket(NULL, 0, IPPROTO_TCP);

    FAIL_IF(unlikely(p == NULL));

    p->flow = f;

    Signature *s = NULL;

    ThreadVars th_v;

    DetectEngineThreadCtx *det_ctx = NULL;

    memset(&th_v, 0, sizeof(th_v));

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();

    FAIL_IF_NULL(de_ctx);

    de_ctx->flags |= DE_QUIET;

    s = de_ctx->sig_list = SigInit(de_ctx,"alert ssh any any -> any any (msg:\"SSH\"; ssh.protoversion:1.10; sid:1;)");

    FAIL_IF_NULL(s);

    SigGroupBuild(de_ctx);

    DetectEngineThreadCtxInit(&th_v, (void *)de_ctx, (void *)&det_ctx);

    uint32_t seq = 2;

    for (int i=0; i<4; i++) {

        FAIL_IF(StreamTcpUTAddSegmentWithPayload(&tv, ra_ctx, &ssn.server, seq, sshbufs[i], sshlens[i]) == -1);

        seq += sshlens[i];

        FAIL_IF(StreamTcpReassembleAppLayer(&tv, ra_ctx, &ssn, &ssn.server, p, UPDATE_DIR_PACKET) < 0);

    }

    void *ssh_state = f->alstate;

    FAIL_IF_NULL(ssh_state);

    /* do detect */

    SigMatchSignatures(&th_v, de_ctx, det_ctx, p);

    FAIL_IF(PacketAlertCheck(p, 1));

    DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);

    DetectEngineCtxFree(de_ctx);

    UTHFreePacket(p);

    StreamTcpUTClearSession(&ssn);

    StreamTcpUTDeinit(ra_ctx);

    UTHFreeFlow(f);

    PASS;

}

/** \test Send a get request in three chunks + more data. */

static int DetectSshVersionTestDetect02(void)

{

    TcpReassemblyThreadCtx *ra_ctx = NULL;

    ThreadVars tv;

    TcpSession ssn;

    Flow *f = NULL;

    Packet *p = NULL;

    uint8_t sshbuf1[] = "SSH-1.99-Pu";

    uint8_t sshbuf2[] = "TTY_2.123" ;

    uint8_t sshbuf3[] = "\n";

    uint8_t sshbuf4[] = "whatever...";

    uint8_t* sshbufs[4] = {sshbuf1, sshbuf2, sshbuf3, sshbuf4};

    uint32_t sshlens[4] = {sizeof(sshbuf1) - 1, sizeof(sshbuf2) - 1, sizeof(sshbuf3) - 1, sizeof(sshbuf4) - 1};

    memset(&tv, 0x00, sizeof(tv));

    StreamTcpUTInit(&ra_ctx);

    StreamTcpUTInitInline();

    StreamTcpUTSetupSession(&ssn);

    StreamTcpUTSetupStream(&ssn.server, 1);

    StreamTcpUTSetupStream(&ssn.client, 1);

    f = UTHBuildFlow(AF_INET, "1.1.1.1", "2.2.2.2", 1234, 2222);

    FAIL_IF_NULL(f);

    f->protoctx = &ssn;

    f->proto = IPPROTO_TCP;

    f->alproto = ALPROTO_SSH;

    p = UTHBuildPacket(NULL, 0, IPPROTO_TCP);

    FAIL_IF(unlikely(p == NULL));

    p->flow = f;

    Signature *s = NULL;

    ThreadVars th_v;

    DetectEngineThreadCtx *det_ctx = NULL;

    memset(&th_v, 0, sizeof(th_v));

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();

    FAIL_IF_NULL(de_ctx);

    de_ctx->flags |= DE_QUIET;

    s = de_ctx->sig_list = SigInit(de_ctx,"alert ssh any any -> any any (msg:\"SSH\"; ssh.protoversion:2_compat; sid:1;)");

    FAIL_IF_NULL(s);

    SigGroupBuild(de_ctx);

    DetectEngineThreadCtxInit(&th_v, (void *)de_ctx, (void *)&det_ctx);

    uint32_t seq = 2;

    for (int i=0; i<4; i++) {

        FAIL_IF(StreamTcpUTAddSegmentWithPayload(&tv, ra_ctx, &ssn.server, seq, sshbufs[i], sshlens[i]) == -1);

        seq += sshlens[i];

        FAIL_IF(StreamTcpReassembleAppLayer(&tv, ra_ctx, &ssn, &ssn.server, p, UPDATE_DIR_PACKET) < 0);

    }

    void *ssh_state = f->alstate;

    FAIL_IF_NULL(ssh_state);

    /* do detect */

    SigMatchSignatures(&th_v, de_ctx, det_ctx, p);

    FAIL_IF(PacketAlertCheck(p, 1));

    DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);

    DetectEngineCtxFree(de_ctx);

    UTHFreePacket(p);

    StreamTcpUTClearSession(&ssn);

    StreamTcpUTDeinit(ra_ctx);

    UTHFreeFlow(f);

    PASS;

}

/** \test Send a get request in three chunks + more data. */

static int DetectSshVersionTestDetect03(void)

{

    TcpReassemblyThreadCtx *ra_ctx = NULL;

    ThreadVars tv;

    TcpSession ssn;

    Flow *f = NULL;

    Packet *p = NULL;

    uint8_t sshbuf1[] = "SSH-1.";

    uint8_t sshbuf2[] = "7-PuTTY_2.123" ;

    uint8_t sshbuf3[] = "\n";

    uint8_t sshbuf4[] = "whatever...";

    uint8_t* sshbufs[4] = {sshbuf1, sshbuf2, sshbuf3, sshbuf4};

    uint32_t sshlens[4] = {sizeof(sshbuf1) - 1, sizeof(sshbuf2) - 1, sizeof(sshbuf3) - 1, sizeof(sshbuf4) - 1};

    memset(&tv, 0x00, sizeof(tv));

    StreamTcpUTInit(&ra_ctx);

    StreamTcpUTInitInline();

    StreamTcpUTSetupSession(&ssn);

    StreamTcpUTSetupStream(&ssn.server, 1);

    StreamTcpUTSetupStream(&ssn.client, 1);

    f = UTHBuildFlow(AF_INET, "1.1.1.1", "2.2.2.2", 1234, 2222);

    FAIL_IF_NULL(f);

    f->protoctx = &ssn;

    f->proto = IPPROTO_TCP;

    f->alproto = ALPROTO_SSH;

    p = UTHBuildPacket(NULL, 0, IPPROTO_TCP);

    FAIL_IF(unlikely(p == NULL));

    p->flow = f;

    Signature *s = NULL;

    ThreadVars th_v;

    DetectEngineThreadCtx *det_ctx = NULL;

    memset(&th_v, 0, sizeof(th_v));

    DetectEngineCtx *de_ctx = DetectEngineCtxInit();

    FAIL_IF_NULL(de_ctx);

    de_ctx->flags |= DE_QUIET;

    s = de_ctx->sig_list = SigInit(de_ctx,"alert ssh any any -> any any (msg:\"SSH\"; ssh.protoversion:2_compat; sid:1;)");

    FAIL_IF_NULL(s);

    SigGroupBuild(de_ctx);

    DetectEngineThreadCtxInit(&th_v, (void *)de_ctx, (void *)&det_ctx);

    uint32_t seq = 2;

    for (int i=0; i<4; i++) {

        FAIL_IF(StreamTcpUTAddSegmentWithPayload(&tv, ra_ctx, &ssn.server, seq, sshbufs[i], sshlens[i]) == -1);

        seq += sshlens[i];

        FAIL_IF(StreamTcpReassembleAppLayer(&tv, ra_ctx, &ssn, &ssn.server, p, UPDATE_DIR_PACKET) < 0);

    }

    void *ssh_state = f->alstate;

    FAIL_IF_NULL(ssh_state);

    /* do detect */

    SigMatchSignatures(&th_v, de_ctx, det_ctx, p);

    FAIL_IF(PacketAlertCheck(p, 1));

    DetectEngineThreadCtxDeinit(&th_v, (void *)det_ctx);

    DetectEngineCtxFree(de_ctx);

    UTHFreePacket(p);

    StreamTcpUTClearSession(&ssn);

    StreamTcpUTDeinit(ra_ctx);

    UTHFreeFlow(f);

    PASS;

}

/**

 * \brief this function registers unit tests for DetectSshVersion

 */

static void DetectSshVersionRegisterTests(void)

{

    UtRegisterTest("DetectSshVersionTestParse01", DetectSshVersionTestParse01);

    UtRegisterTest("DetectSshVersionTestParse02", DetectSshVersionTestParse02);

    UtRegisterTest("DetectSshVersionTestParse03", DetectSshVersionTestParse03);

    UtRegisterTest("DetectSshVersionTestDetect01",

                   DetectSshVersionTestDetect01);

    UtRegisterTest("DetectSshVersionTestDetect02",

                   DetectSshVersionTestDetect02);

    UtRegisterTest("DetectSshVersionTestDetect03",

                   DetectSshVersionTestDetect03);

}

#endif /* UNITTESTS */