2012/12/18 <scm-com...@wald.intevation.org>: > Author: jan > Date: 2012-12-18 22:31:13 +0100 (Tue, 18 Dec 2012) > New Revision: 14885 > > Modified: > trunk/openvas-libraries/COPYING > trunk/openvas-libraries/ChangeLog > trunk/openvas-libraries/base/cvss.c > trunk/openvas-libraries/base/cvss.h > Log: > * COPYING: Added cvss module. > * base/cvss.c (cvss_as_str): New. > * base/cvss.h: Added proto accordingly.
Hello,
I have some concerns regarding this new cvss.c file.
- It doesn't match the style and coding standards of the codebase.
- It doesn't leverage the glib functions.
- The final free(token) seems broken. Unless I miss something we
have the following pattern:
while (token != NULL)
{ ... }
free(token); <-- ??
- Readability is not optimal.
I tried to improve it a bit. Please find a patch attached. If people
prefer this version I can polish the documentation and commit it.
I've added a standalone version (cvss_prog.c) to ease testing. That's
exactly the same file, with a main version to take a cvss base vector
as argv[1] and print out the corresponding score.
Regards
--
Henri
cvss_cleanup.diff
Description: Binary data
/* openvas-libraries/base
* $Id$
* Description: CVSS utility functions
*
* Authors:
* Preeti Subramanian
*
* Copyright:
* Copyright (C) 2012 Greenbone Networks GmbH
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2,
* or, at your option, any later version 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
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* @file cvss.c
* @brief CVSS utility functions
*
* This file contains utitlity functions for handlung CVSS.
* Namels a calculator for the CVSS base score from a CVSS base
* vector.
*
* The base equation is the foundation of CVSS scoring. The base equation is:
* BaseScore6 = round_to_1_decimal(((0.6*Impact)+(0.4*Exploitability)–1.5)*f(Impact))
* Impact = 10.41*(1-(1-ConfImpact)*(1-IntegImpact)*(1-AvailImpact))
* Exploitability = 20* AccessVector*AccessComplexity*Authentication
*
* f(impact)= 0 if Impact=0, 1.176 otherwise
* AccessVector = case AccessVector of
* requires local access: 0.395
* adjacent network accessible: 0.646
* network accessible: 1.0
* AccessComplexity = case AccessComplexity of
* high: 0.35
* medium: 0.61
* low: 0.71
* Authentication = case Authentication of
* requires multiple instances of authentication: 0.45
* requires single instance of authentication: 0.56
* requires no authentication: 0.704
* ConfImpact = case ConfidentialityImpact of
* none: 0.0
* partial: 0.275
* complete: 0.660
* IntegImpact = case IntegrityImpact of
* none: 0.0
* partial: 0.275
* complete: 0.660
* AvailImpact = case AvailabilityImpact of
* none: 0.0
* partial: 0.275
* complete: 0.660
*/
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <glib.h>
/* AccessVector (AV) Constants */
#define AV_NETWORK 1.0
#define AV_ADJACENT_NETWORK 0.646
#define AV_LOCAL 0.395
/* AccessComplexity (AC) Constants */
#define AC_LOW 0.71
#define AC_MEDIUM 0.61
#define AC_HIGH 0.35
/* Authentication (Au) Constants */
#define Au_MULTIPLE_INSTANCES 0.45
#define Au_SINGLE_INSTANCE 0.56
#define Au_NONE 0.704
/* ConfidentialityImpact (C) Constants */
#define C_NONE 0.0
#define C_PARTIAL 0.275
#define C_COMPLETE 0.660
/* IntegrityImpact (I) Constants */
#define I_NONE 0.0
#define I_PARTIAL 0.275
#define I_COMPLETE 0.660
/* AvailabilityImpact (A) Constants */
#define A_NONE 0.0
#define A_PARTIAL 0.275
#define A_COMPLETE 0.660
enum base_metrics { A, I, C, Au, AC, AV };
struct impact_item
{
const char *name;
double nvalue;
};
static const struct impact_item impact_map[][3] = {
[A] = {
{"N", A_NONE},
{"P", A_PARTIAL},
{"C", A_COMPLETE},
},
[I] = {
{"N", I_NONE},
{"P", I_PARTIAL},
{"C", I_COMPLETE},
},
[C] = {
{"N", C_NONE},
{"P", C_PARTIAL},
{"C", C_COMPLETE},
},
[Au] = {
{"N", Au_NONE},
{"M", Au_MULTIPLE_INSTANCES},
{"C", Au_SINGLE_INSTANCE},
},
[AV] = {
{"N", AV_NETWORK},
{"A", AV_ADJACENT_NETWORK},
{"L", AV_LOCAL},
},
[AC] = {
{"L", AC_LOW},
{"M", AC_MEDIUM},
{"H", AC_HIGH},
},
};
struct cvss
{
double conf_impact;
double integ_impact;
double avail_impact;
double access_vector;
double access_complexity;
double authentication;
};
/**
* @brief Determin base metric enumeration from a string.
*
* @param str Base metric in string form, for example "A".
*
* @return The respective base_metric enumeration for the
* string. -1 in case parsing the string failed.
*/
static enum base_metrics
metricname2enum (char * str)
{
if (g_strcmp0(str, "A") == 0)
return A;
else if (g_strcmp0(str, "I") == 0)
return I;
else if (g_strcmp0(str, "C") == 0)
return C;
else if (g_strcmp0(str, "Au") == 0)
return Au;
else if (g_strcmp0(str, "AV") == 0)
return AV;
else if (g_strcmp0(str, "AC") == 0)
return AC;
return -1;
}
/**
* @brief Calculate Impact Sub Score.
*
* @return The resulting sub score.
*/
static double
get_impact_subscore (const struct cvss *cvss)
{
return (10.41 * (1 -
(1 - cvss->conf_impact) *
(1 - cvss->integ_impact) *
(1 - cvss->avail_impact)));
}
/**
* @brief Calculate Exploitability Sub Score.
*
* @return The resulting sub score.
*/
static double
get_exploitability_subscore (const struct cvss *cvss)
{
return (20 * cvss->access_vector *
cvss->access_complexity * cvss->authentication);
}
static inline int
get_impact_from_str (const char *value, enum base_metrics metric,
struct cvss *cvss)
{
int i;
for (i = 0; i < 3; i++)
{
const struct impact_item *impact;
impact = &impact_map[metric][i];
if (g_strcmp0 (impact->name, value) == 0)
{
switch (metric)
{
case A:
cvss->avail_impact = impact->nvalue;
break;
case I:
cvss->integ_impact = impact->nvalue;
break;
case C:
cvss->conf_impact = impact->nvalue;
break;
case Au:
cvss->authentication = impact->nvalue;
break;
case AV:
cvss->access_vector = impact->nvalue;
break;
case AC:
cvss->access_complexity = impact->nvalue;
break;
default:
return -1;
}
return 0;
}
}
return -1;
}
static double
__get_cvss_score (struct cvss *cvss)
{
double impact = 1.176;
double impact_sub;
double exploitability_sub;
impact_sub = get_impact_subscore (cvss);
exploitability_sub = get_exploitability_subscore (cvss);
if (impact_sub < 0.1)
impact = 0.0;
return (((0.6 * impact_sub) + (0.4 * exploitability_sub) - 1.5) * impact);
}
/**
* @brief Calculate CVSS Score.
*
* @param base_metrics Base vector string from which to compute score.
*
* @return The resulting score. -1 upon error during parsing.
*/
double
get_cvss_score_from_base_metrics (char *base_metrics)
{
struct cvss cvss;
char *token, *base_str;
memset(&cvss, 0x00, sizeof(struct cvss));
if (base_metrics == NULL)
return 0.0;
base_str = base_metrics = g_strdup_printf ("%s/", base_metrics);
while ((token = strchr (base_metrics, '/')) != NULL)
{
char *token2 = strtok (base_metrics, ":");
char *metric_name = token2;
char *metric_value;
*token++ = '\0';
if (metric_name == NULL)
return (double)-1;
metric_value = strtok (NULL, ":");
if (metric_value == NULL)
return (double)-1;
if (get_impact_from_str (metric_value, metricname2enum (metric_name), &cvss))
return (double)-1;
base_metrics = token;
}
free(base_str);
return __get_cvss_score(&cvss);
}
int main(int ac, char **av) {
if (ac < 2)
{
fprintf(stderr, "Usage: %s <CVSS base vector>\n", av[0]);
return 1;
}
printf("CVSS for %s => %.03f\n", av[1], get_cvss_score_from_base_metrics(av[1]));
return 0;
}
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