suricata/src/detect-mark.c

/* Copyright (C) 2011 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 Eric Leblond <eric@regit.org>
 *
 * Implements the mark keyword. Based  on detect-gid
 * by Breno Silva <breno.silva@gmail.com>
 */

#include "suricata-common.h"
#include "suricata.h"
#include "decode.h"
#include "detect.h"
#include "flow-var.h"
#include "decode-events.h"

#include "detect-mark.h"
#include "detect-parse.h"

#include "util-unittest.h"
#include "util-debug.h"

#define PARSE_REGEX "([0x]*[0-9a-f]+)/([0x]*[0-9a-f]+)"

static pcre *parse_regex;
static pcre_extra *parse_regex_study;

static int DetectMarkSetup (DetectEngineCtx *, Signature *, char *);
int DetectMarkPacket(ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, SigMatch *m);
void DetectMarkDataFree(void *ptr);

/**
 * \brief Registration function for nfq_set_mark: keyword
 */

void DetectMarkRegister (void) {
    sigmatch_table[DETECT_MARK].name = "nfq_set_mark";
    sigmatch_table[DETECT_MARK].Match = DetectMarkPacket;
    sigmatch_table[DETECT_MARK].Setup = DetectMarkSetup;
    sigmatch_table[DETECT_MARK].Free  = DetectMarkDataFree;
    sigmatch_table[DETECT_MARK].RegisterTests = MarkRegisterTests;

    const char *eb;
    int opts = 0;
    int eo;

    parse_regex = pcre_compile(PARSE_REGEX, opts, &eb, &eo, NULL);
    if(parse_regex == NULL)
    {
        SCLogError(SC_ERR_PCRE_COMPILE, "pcre compile of \"%s\" failed at offset %" PRId32 ": %s", PARSE_REGEX, eo, eb);
        goto error;
    }

    parse_regex_study = pcre_study(parse_regex, 0, &eb);
    if(eb != NULL)
    {
        SCLogError(SC_ERR_PCRE_STUDY, "pcre study failed: %s", eb);
        goto error;
    }

error:
    return;

}

#ifdef NFQ
/**
 * \internal
 * \brief This function is used to parse mark options passed via mark: keyword
 *
 * \param rawstr Pointer to the user provided mark options
 *
 * \retval 0 on success
 * \retval < 0 on failure
 */
static void * DetectMarkParse (char *rawstr)
{
    int ret = 0, res = 0;
#define MAX_SUBSTRINGS 30
    int ov[MAX_SUBSTRINGS];
    const char *str_ptr = NULL;
    char *ptr = NULL;
    char *endptr = NULL;
    uint32_t mark;
    uint32_t mask;
    DetectMarkData *data;

    ret = pcre_exec(parse_regex, parse_regex_study, rawstr, strlen(rawstr), 0, 0, ov, MAX_SUBSTRINGS);
    if (ret < 1) {
        SCLogError(SC_ERR_PCRE_MATCH, "pcre_exec parse error, ret %" PRId32 ", string %s", ret, rawstr);
        return NULL;
    }

    res = pcre_get_substring((char *)rawstr, ov, MAX_SUBSTRINGS, 1, &str_ptr);
    if (res < 0) {
        SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
        return NULL;
    }

    ptr = (char *)str_ptr;

    if (ptr == NULL)
        return NULL;

    errno = 0;
    mark = strtoul(ptr, &endptr, 0);
    if (errno == ERANGE) {
        SCLogError(SC_ERR_NUMERIC_VALUE_ERANGE, "Numeric value out of range");
        SCFree(ptr);
        return NULL;
    }     /* If there is no numeric value in the given string then strtoull(), makes
             endptr equals to ptr and return 0 as result */
    else if (endptr == ptr && mark == 0) {
        SCLogError(SC_ERR_INVALID_NUMERIC_VALUE, "No numeric value");
        SCFree(ptr);
        return NULL;
    } else if (endptr == ptr) {
        SCLogError(SC_ERR_INVALID_NUMERIC_VALUE, "Invalid numeric value");
        SCFree(ptr);
        return NULL;
    }

    res = pcre_get_substring((char *)rawstr, ov, MAX_SUBSTRINGS, 2, &str_ptr);
    if (res < 0) {
        SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_get_substring failed");
        return NULL;
    }

    SCFree(ptr);
    ptr = (char *)str_ptr;

    if (ptr == NULL) {
        data = SCMalloc(sizeof(DetectMarkData));
        if (data == NULL) {
            return NULL;
        }
        data->mark = mark;
        data->mask = 0xffff;
        return data;
    }

    errno = 0;
    mask = strtoul(ptr, &endptr, 0);
    if (errno == ERANGE) {
        SCLogError(SC_ERR_NUMERIC_VALUE_ERANGE, "Numeric value out of range");
        SCFree(ptr);
        return NULL;
    }     /* If there is no numeric value in the given string then strtoull(), makes
             endptr equals to ptr and return 0 as result */
    else if (endptr == ptr && mask == 0) {
        SCLogError(SC_ERR_INVALID_NUMERIC_VALUE, "No numeric value");
        SCFree(ptr);
        return NULL;
    }
    else if (endptr == ptr) {
        SCLogError(SC_ERR_INVALID_NUMERIC_VALUE, "Invalid numeric value");
        SCFree(ptr);
        return NULL;
    }

    SCLogDebug("Rule will set mark 0x%x with mask 0x%x", mark, mask);
    SCFree(ptr);

    data = SCMalloc(sizeof(DetectMarkData));
    if (data == NULL) {
        return NULL;
    }
    data->mark = mark;
    data->mask = mask;
    return data;
}

#endif /* NFQ */

/**
 * \internal
 * \brief this function is used to add the parsed mark into the current signature
 *
 * \param de_ctx pointer to the Detection Engine Context
 * \param s pointer to the Current Signature
 * \param rawstr pointer to the user provided mark options
 *
 * \retval 0 on Success
 * \retval -1 on Failure
 */
static int DetectMarkSetup (DetectEngineCtx *de_ctx, Signature *s, char *rawstr)
{
#ifdef NFQ
    DetectMarkData *data = NULL;
    SigMatch *sm = NULL;

    data = DetectMarkParse(rawstr);

    if (data == NULL) {
        return -1;
    } else {
        sm = SigMatchAlloc();
        if (sm == NULL) {
            DetectMarkDataFree(data);
            return -1;
        }

        sm->type = DETECT_MARK;
        sm->ctx = (void *)data;

        /* Append it to the list of tags */
        SigMatchAppendTag(s, sm);
        return 0;
    }
#else
    return 0;
#endif
}

void DetectMarkDataFree(void *ptr)
{
    DetectMarkData *data = (DetectMarkData *)ptr;
    SCFree(data);
}


int DetectMarkPacket(ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, SigMatch *m)
{
#ifdef NFQ
    DetectMarkData *nf_data = (DetectMarkData *) m->ctx;
    if (nf_data->mask) {
        p->nfq_v.mark = (nf_data->mark & nf_data->mask)
                        | (p->nfq_v.mark & ~(nf_data->mask));
        p->flags |= PKT_MARK_MODIFIED;
    }
#endif
    return 1;
}

/*
 * ONLY TESTS BELOW THIS COMMENT
 */

#if defined UNITTESTS && defined NFQ
/**
 * \test MarkTestParse01 is a test for a valid mark value
 *
 *  \retval 1 on succces
 *  \retval 0 on failure
 */
static int MarkTestParse01 (void) {
    DetectMarkData *data;

    data = DetectMarkParse("1/1");

    if (data == NULL) {
        return 0;
    }

    DetectMarkDataFree(data);
    return 1;
}

/**
 * \test MarkTestParse02 is a test for an invalid mark value
 *
 *  \retval 1 on succces
 *  \retval 0 on failure
 */
static int MarkTestParse02 (void) {
    DetectMarkData *data;

    data = DetectMarkParse("4");

    if (data == NULL) {
        return 0;
    }

    DetectMarkDataFree(data);
    return 1;
}

/**
 * \test MarkTestParse03 is a test for a valid mark value
 *
 *  \retval 1 on succces
 *  \retval 0 on failure
 */
static int MarkTestParse03 (void) {
    DetectMarkData *data;

    data = DetectMarkParse("0x10/0xff");

    if (data == NULL) {
        return 0;
    }

    DetectMarkDataFree(data);
    return 1;
}

/**
 * \test MarkTestParse04 is a test for a invalid mark value
 *
 *  \retval 1 on succces
 *  \retval 0 on failure
 */
static int MarkTestParse04 (void) {
    DetectMarkData *data;

    data = DetectMarkParse("0x1g/0xff");

    if (data == NULL) {
        return 0;
    }

    DetectMarkDataFree(data);
    return 1;
}



#endif /* UNITTESTS */

/**
 * \brief this function registers unit tests for Mark
 */
void MarkRegisterTests(void) {
#if defined UNITTESTS && defined NFQ
    UtRegisterTest("MarkTestParse01", MarkTestParse01, 1);
    UtRegisterTest("MarkTestParse02", MarkTestParse02, 0);
    UtRegisterTest("MarkTestParse03", MarkTestParse03, 1);
    UtRegisterTest("MarkTestParse04", MarkTestParse04, 0);
#endif /* UNITTESTS */
}