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rhel.go
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rhel.go
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// Copyright 2015 clair authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// 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
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package rhel
import (
"bufio"
"encoding/xml"
"io"
"net/http"
"regexp"
"strconv"
"strings"
"github.com/coreos/clair/database"
"github.com/coreos/clair/updater"
cerrors "github.com/coreos/clair/utils/errors"
"github.com/coreos/clair/utils/types"
"github.com/coreos/pkg/capnslog"
)
const (
// Before this RHSA, it deals only with RHEL <= 4.
firstRHEL5RHSA = 20070044
firstConsideredRHEL = 5
ovalURI = "https://www.redhat.com/security/data/oval/"
rhsaFilePrefix = "com.redhat.rhsa-"
updaterFlag = "rhelUpdater"
)
var (
ignoredCriterions = []string{
" is signed with Red Hat ",
" Client is installed",
" Workstation is installed",
" ComputeNode is installed",
}
rhsaRegexp = regexp.MustCompile(`com.redhat.rhsa-(\d+).xml`)
log = capnslog.NewPackageLogger("github.com/coreos/clair", "updater/fetchers/rhel")
)
type oval struct {
Definitions []definition `xml:"definitions>definition"`
}
type definition struct {
Title string `xml:"metadata>title"`
Description string `xml:"metadata>description"`
References []reference `xml:"metadata>reference"`
Criteria criteria `xml:"criteria"`
}
type reference struct {
Source string `xml:"source,attr"`
URI string `xml:"ref_url,attr"`
}
type criteria struct {
Operator string `xml:"operator,attr"`
Criterias []*criteria `xml:"criteria"`
Criterions []criterion `xml:"criterion"`
}
type criterion struct {
Comment string `xml:"comment,attr"`
}
// RHELFetcher implements updater.Fetcher and gets vulnerability updates from
// the Red Hat OVAL definitions.
type RHELFetcher struct{}
func init() {
updater.RegisterFetcher("Red Hat", &RHELFetcher{})
}
// FetchUpdate gets vulnerability updates from the Red Hat OVAL definitions.
func (f *RHELFetcher) FetchUpdate(datastore database.Datastore) (resp updater.FetcherResponse, err error) {
log.Info("fetching Red Hat vulnerabilities")
// Get the first RHSA we have to manage.
flagValue, err := datastore.GetKeyValue(updaterFlag)
if err != nil {
return resp, err
}
firstRHSA, err := strconv.Atoi(flagValue)
if firstRHSA == 0 || err != nil {
firstRHSA = firstRHEL5RHSA
}
// Fetch the update list.
r, err := http.Get(ovalURI)
if err != nil {
log.Errorf("could not download RHEL's update list: %s", err)
return resp, cerrors.ErrCouldNotDownload
}
// Get the list of RHSAs that we have to process.
var rhsaList []int
scanner := bufio.NewScanner(r.Body)
for scanner.Scan() {
line := scanner.Text()
r := rhsaRegexp.FindStringSubmatch(line)
if len(r) == 2 {
rhsaNo, _ := strconv.Atoi(r[1])
if rhsaNo > firstRHSA {
rhsaList = append(rhsaList, rhsaNo)
}
}
}
for _, rhsa := range rhsaList {
// Download the RHSA's XML file.
r, err := http.Get(ovalURI + rhsaFilePrefix + strconv.Itoa(rhsa) + ".xml")
if err != nil {
log.Errorf("could not download RHEL's update file: %s", err)
return resp, cerrors.ErrCouldNotDownload
}
// Parse the XML.
vs, err := parseRHSA(r.Body)
if err != nil {
return resp, err
}
// Collect vulnerabilities.
for _, v := range vs {
resp.Vulnerabilities = append(resp.Vulnerabilities, v)
}
}
// Set the flag if we found anything.
if len(rhsaList) > 0 {
resp.FlagName = updaterFlag
resp.FlagValue = strconv.Itoa(rhsaList[len(rhsaList)-1])
} else {
log.Debug("no Red Hat update.")
}
return resp, nil
}
func parseRHSA(ovalReader io.Reader) (vulnerabilities []database.Vulnerability, err error) {
// Decode the XML.
var ov oval
err = xml.NewDecoder(ovalReader).Decode(&ov)
if err != nil {
log.Errorf("could not decode RHEL's XML: %s", err)
err = cerrors.ErrCouldNotParse
return
}
// Iterate over the definitions and collect any vulnerabilities that affect
// at least one package.
for _, definition := range ov.Definitions {
pkgs := toFeatureVersions(definition.Criteria)
if len(pkgs) > 0 {
vulnerability := database.Vulnerability{
Name: name(definition),
Link: link(definition),
Severity: priority(definition),
Description: description(definition),
}
for _, p := range pkgs {
vulnerability.FixedIn = append(vulnerability.FixedIn, p)
}
vulnerabilities = append(vulnerabilities, vulnerability)
}
}
return
}
func getCriterions(node criteria) [][]criterion {
// Filter useless criterions.
var criterions []criterion
for _, c := range node.Criterions {
ignored := false
for _, ignoredItem := range ignoredCriterions {
if strings.Contains(c.Comment, ignoredItem) {
ignored = true
break
}
}
if !ignored {
criterions = append(criterions, c)
}
}
if node.Operator == "AND" {
return [][]criterion{criterions}
} else if node.Operator == "OR" {
var possibilities [][]criterion
for _, c := range criterions {
possibilities = append(possibilities, []criterion{c})
}
return possibilities
}
return [][]criterion{}
}
func getPossibilities(node criteria) [][]criterion {
if len(node.Criterias) == 0 {
return getCriterions(node)
}
var possibilitiesToCompose [][][]criterion
for _, criteria := range node.Criterias {
possibilitiesToCompose = append(possibilitiesToCompose, getPossibilities(*criteria))
}
if len(node.Criterions) > 0 {
possibilitiesToCompose = append(possibilitiesToCompose, getCriterions(node))
}
var possibilities [][]criterion
if node.Operator == "AND" {
for _, possibility := range possibilitiesToCompose[0] {
possibilities = append(possibilities, possibility)
}
for _, possibilityGroup := range possibilitiesToCompose[1:] {
var newPossibilities [][]criterion
for _, possibility := range possibilities {
for _, possibilityInGroup := range possibilityGroup {
var p []criterion
p = append(p, possibility...)
p = append(p, possibilityInGroup...)
newPossibilities = append(newPossibilities, p)
}
}
possibilities = newPossibilities
}
} else if node.Operator == "OR" {
for _, possibilityGroup := range possibilitiesToCompose {
for _, possibility := range possibilityGroup {
possibilities = append(possibilities, possibility)
}
}
}
return possibilities
}
func toFeatureVersions(criteria criteria) []database.FeatureVersion {
// There are duplicates in Red Hat .xml files.
// This map is for deduplication.
featureVersionParameters := make(map[string]database.FeatureVersion)
possibilities := getPossibilities(criteria)
for _, criterions := range possibilities {
var (
featureVersion database.FeatureVersion
osVersion int
err error
)
// Attempt to parse package data from trees of criterions.
for _, c := range criterions {
if strings.Contains(c.Comment, " is installed") {
const prefixLen = len("Red Hat Enterprise Linux ")
osVersion, err = strconv.Atoi(strings.TrimSpace(c.Comment[prefixLen : prefixLen+strings.Index(c.Comment[prefixLen:], " ")]))
if err != nil {
log.Warningf("could not parse Red Hat release version from: '%s'.", c.Comment)
}
} else if strings.Contains(c.Comment, " is earlier than ") {
const prefixLen = len(" is earlier than ")
featureVersion.Feature.Name = strings.TrimSpace(c.Comment[:strings.Index(c.Comment, " is earlier than ")])
featureVersion.Version, err = types.NewVersion(c.Comment[strings.Index(c.Comment, " is earlier than ")+prefixLen:])
if err != nil {
log.Warningf("could not parse package version '%s': %s. skipping", c.Comment[strings.Index(c.Comment, " is earlier than ")+prefixLen:], err.Error())
}
}
}
if osVersion >= firstConsideredRHEL {
// TODO(vbatts) this is where features need multiple labels ('centos' and 'rhel')
featureVersion.Feature.Namespace.Name = "centos" + ":" + strconv.Itoa(osVersion)
} else {
continue
}
if featureVersion.Feature.Namespace.Name != "" && featureVersion.Feature.Name != "" && featureVersion.Version.String() != "" {
featureVersionParameters[featureVersion.Feature.Namespace.Name+":"+featureVersion.Feature.Name] = featureVersion
} else {
log.Warningf("could not determine a valid package from criterions: %v", criterions)
}
}
// Convert the map to slice.
var featureVersionParametersArray []database.FeatureVersion
for _, fv := range featureVersionParameters {
featureVersionParametersArray = append(featureVersionParametersArray, fv)
}
return featureVersionParametersArray
}
func description(def definition) (desc string) {
// It is much more faster to proceed like this than using a Replacer.
desc = strings.Replace(def.Description, "\n\n\n", " ", -1)
desc = strings.Replace(desc, "\n\n", " ", -1)
desc = strings.Replace(desc, "\n", " ", -1)
return
}
func name(def definition) string {
return strings.TrimSpace(def.Title[:strings.Index(def.Title, ": ")])
}
func link(def definition) (link string) {
for _, reference := range def.References {
if reference.Source == "RHSA" {
link = reference.URI
break
}
}
return
}
func priority(def definition) types.Priority {
// Parse the priority.
priority := strings.TrimSpace(def.Title[strings.LastIndex(def.Title, "(")+1 : len(def.Title)-1])
// Normalize the priority.
switch priority {
case "Low":
return types.Low
case "Moderate":
return types.Medium
case "Important":
return types.High
case "Critical":
return types.Critical
default:
log.Warning("could not determine vulnerability priority from: %s.", priority)
return types.Unknown
}
}
// Clean deletes any allocated resources.
func (f *RHELFetcher) Clean() {}