niceSOFT/libmodsecurity: ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. It has a robust event-based programming language which provides protection from a range of attacks against web applications and allows for HTTP traffic monitoring, logging and real-time analysis.

src/variables/xml.cc

142 строки4 KB

Felipe Zimmerle

Fix memory issues while resolving variables

28 авг 2017, 04:06

28 авг 2017, 04:067ac6bf7

/*
 * ModSecurity, http://www.modsecurity.org/
 * Copyright (c) 2015 Trustwave Holdings, Inc. (http://www.trustwave.com/)
 *
 * You may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * If any of the files related to licensing are missing or if you have any
 * other questions related to licensing please contact Trustwave Holdings, Inc.
 * directly using the email address security@modsecurity.org.
 *
 */

#include "src/variables/xml.h"

#include <time.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <libxml/xmlschemas.h>
#include <libxml/xpath.h>
#include <libxml/tree.h>
#include <libxml/parser.h>
#include <libxml/xpathInternals.h>

#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <utility>

#include "modsecurity/transaction.h"
#include "modsecurity/rules_properties.h"
#include "modsecurity/rules.h"

#include "src/request_body_processor/xml.h"
#include "modsecurity/actions/action.h"
#include "src/actions/xmlns.h"

namespace modsecurity {
namespace Variables {

void XML::evaluate(Transaction *t,
    Rule *rule,
    std::vector<const collection::Variable *> *l) {
    xmlXPathContextPtr xpathCtx;
    xmlXPathObjectPtr xpathObj;
    xmlNodeSetPtr nodes;
    std::string param;
    const xmlChar* xpathExpr = NULL;
    int i;
    size_t pos;

    param = m_name;
    pos = m_name.find_first_of(":");
    if (pos == std::string::npos) {
        param = "";
    } else {
        param = std::string(m_name, pos+1, m_name.length() - (pos + 1));
    }

    /* Is there an XML document tree at all? */
    if (t->m_xml->m_data.doc == NULL) {
        /* Sorry, we've got nothing to give! */
        return;
    }

    /* Process the XPath expression. */
    xpathExpr = (const xmlChar*)param.c_str();
    xpathCtx = xmlXPathNewContext(t->m_xml->m_data.doc);
    if (xpathCtx == NULL) {
#ifndef NO_LOGS
        t->debug(1, "XML: Unable to create new XPath context. : ");
#endif
        return;
    }

    if (rule == NULL) {
#ifndef NO_LOGS
        t->debug(2, "XML: Can't look for xmlns, internal error.");
#endif
    } else {
        std::vector<actions::Action *> acts = rule->getActionsByName("xmlns");
        for (auto &x : acts) {
            actions::XmlNS *z = (actions::XmlNS *)x;
            if (xmlXPathRegisterNs(xpathCtx, (const xmlChar*)z->m_scope.c_str(),
                    (const xmlChar*)z->m_href.c_str()) != 0) {
#ifndef NO_LOGS
                t->debug(1, "Failed to register XML namespace href \"" + \
                    z->m_href + "\" prefix \"" + z->m_scope + "\".");
#endif
                return;
            }

#ifndef NO_LOGS
            t->debug(4, "Registered XML namespace href \"" + z->m_href + \
                "\" prefix \"" + z->m_scope + "\"");
#endif
        }
    }

    /* Initialise XPath expression. */
    xpathObj = xmlXPathEvalExpression(xpathExpr, xpathCtx);
    if (xpathObj == NULL) {
#ifndef NO_LOGS
        t->debug(1, "XML: Unable to evaluate xpath expression.");
#endif
        xmlXPathFreeContext(xpathCtx);
        return;
    }
    /* Evaluate XPath expression. */
    nodes = xpathObj->nodesetval;
    if (nodes == NULL) {
        xmlXPathFreeObject(xpathObj);
        xmlXPathFreeContext(xpathCtx);
        return;
    }
    /* Create one variable for each node in the result. */
    for (i = 0; i < nodes->nodeNr; i++) {
        char *content;
        content = reinterpret_cast<char *>(
            xmlNodeGetContent(nodes->nodeTab[i]));
        if (content != NULL) {
            std::string *a = new std::string(content);
            collection::Variable *var = new collection::Variable(&m_name,
                a);
            delete a;
            l->push_back(var);
            xmlFree(content);
         }
    }
    xmlXPathFreeObject(xpathObj);
    xmlXPathFreeContext(xpathCtx);
}


}  // namespace Variables
}  // namespace modsecurity