/
ubuntu.go
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/
ubuntu.go
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// Copyright 2017 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 ubuntu implements a vulnerability source updater using the
// Ubuntu CVE Tracker.
package ubuntu
import (
"bufio"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"regexp"
"strings"
log "github.com/sirupsen/logrus"
"github.com/coreos/clair/database"
"github.com/coreos/clair/ext/versionfmt"
"github.com/coreos/clair/ext/versionfmt/dpkg"
"github.com/coreos/clair/ext/vulnsrc"
"github.com/coreos/clair/pkg/commonerr"
)
const (
trackerGitURL = "https://git.launchpad.net/ubuntu-cve-tracker"
updaterFlag = "ubuntuUpdater"
cveURL = "http://people.ubuntu.com/~ubuntu-security/cve/%s"
)
var (
ubuntuIgnoredReleases = map[string]struct{}{
"upstream": {},
"devel": {},
"dapper": {},
"edgy": {},
"feisty": {},
"gutsy": {},
"hardy": {},
"intrepid": {},
"jaunty": {},
"karmic": {},
"lucid": {},
"maverick": {},
"natty": {},
"oneiric": {},
"saucy": {},
"vivid/ubuntu-core": {},
"vivid/stable-phone-overlay": {},
// Syntax error
"Patches": {},
// Product
"product": {},
}
affectsCaptureRegexp = regexp.MustCompile(`(?P<release>.*)_(?P<package>.*): (?P<status>[^\s]*)( \(+(?P<note>[^()]*)\)+)?`)
affectsCaptureRegexpNames = affectsCaptureRegexp.SubexpNames()
)
type updater struct {
repositoryLocalPath string
}
func init() {
vulnsrc.RegisterUpdater("ubuntu", &updater{})
}
func (u *updater) Update(datastore database.Datastore) (resp vulnsrc.UpdateResponse, err error) {
log.WithField("package", "Ubuntu").Info("Start fetching vulnerabilities")
// Pull the master branch.
var commit string
commit, err = u.pullRepository()
if err != nil {
return
}
// Get the latest revision number we successfully applied in the database.
dbCommit, err := datastore.GetKeyValue(updaterFlag)
if err != nil {
return resp, err
}
// Short-circuit if there have been no updates.
if commit == dbCommit {
log.WithField("package", "ubuntu").Debug("no update")
return
}
// Get the list of vulnerabilities that we have to update.
modifiedCVE, err := collectModifiedVulnerabilities(u.repositoryLocalPath)
if err != nil {
return resp, err
}
notes := make(map[string]struct{})
for cvePath := range modifiedCVE {
// Open the CVE file.
file, err := os.Open(u.repositoryLocalPath + "/" + cvePath)
if err != nil {
// This can happen when a file is modified and then moved in another
// commit.
continue
}
// Parse the vulnerability.
v, unknownReleases, err := parseUbuntuCVE(file)
if err != nil {
return resp, err
}
// Add the vulnerability to the response.
resp.Vulnerabilities = append(resp.Vulnerabilities, v)
// Store any unknown releases as notes.
for k := range unknownReleases {
note := fmt.Sprintf("Ubuntu %s is not mapped to any version number (eg. trusty->14.04). Please update me.", k)
notes[note] = struct{}{}
// If we encountered unknown Ubuntu release, we don't want the revision
// number to be considered as managed.
commit = dbCommit
}
// Close the file manually.
//
// We do that instead of using defer because defer works on a function-level scope.
// We would open many files and close them all at once at the end of the function,
// which could lead to exceed fs.file-max.
file.Close()
}
// Add flag and notes.
resp.FlagName = updaterFlag
resp.FlagValue = commit
for note := range notes {
resp.Notes = append(resp.Notes, note)
}
return
}
func (u *updater) Clean() {
os.RemoveAll(u.repositoryLocalPath)
}
func (u *updater) pullRepository() (commit string, err error) {
// If the repository doesn't exist, clone it.
if _, pathExists := os.Stat(u.repositoryLocalPath); u.repositoryLocalPath == "" || os.IsNotExist(pathExists) {
if u.repositoryLocalPath, err = ioutil.TempDir(os.TempDir(), "ubuntu-cve-tracker"); err != nil {
return "", vulnsrc.ErrFilesystem
}
cmd := exec.Command("git", "clone", trackerGitURL, ".")
cmd.Dir = u.repositoryLocalPath
if out, err := cmd.CombinedOutput(); err != nil {
u.Clean()
log.WithError(err).WithField("output", string(out)).Error("could not pull ubuntu-cve-tracker repository")
return "", commonerr.ErrCouldNotDownload
}
} else {
// The repository already exists and it needs to be refreshed via a pull.
cmd := exec.Command("git", "pull")
cmd.Dir = u.repositoryLocalPath
if _, err := cmd.CombinedOutput(); err != nil {
return "", vulnsrc.ErrGitFailure
}
}
cmd := exec.Command("git", "rev-parse", "HEAD")
cmd.Dir = u.repositoryLocalPath
out, err := cmd.CombinedOutput()
if err != nil {
return "", vulnsrc.ErrGitFailure
}
commit = strings.TrimSpace(string(out))
return
}
func collectModifiedVulnerabilities(repositoryLocalPath string) (map[string]struct{}, error) {
modifiedCVE := make(map[string]struct{})
// Handle a brand new database.
for _, folder := range []string{"active", "retired"} {
d, err := os.Open(repositoryLocalPath + "/" + folder)
if err != nil {
log.WithError(err).Error("could not open Ubuntu vulnerabilities repository's folder")
return nil, vulnsrc.ErrFilesystem
}
// Get the FileInfo of all the files in the directory.
names, err := d.Readdirnames(-1)
if err != nil {
log.WithError(err).Error("could not read Ubuntu vulnerabilities repository's folder")
return nil, vulnsrc.ErrFilesystem
}
// Add the vulnerabilities to the list.
for _, name := range names {
if strings.HasPrefix(name, "CVE-") {
modifiedCVE[folder+"/"+name] = struct{}{}
}
}
// Close the file manually.
//
// We do that instead of using defer because defer works on a function-level scope.
// We would open many files and close them all at once at the end of the function,
// which could lead to exceed fs.file-max.
d.Close()
}
return modifiedCVE, nil
}
func parseUbuntuCVE(fileContent io.Reader) (vulnerability database.Vulnerability, unknownReleases map[string]struct{}, err error) {
unknownReleases = make(map[string]struct{})
readingDescription := false
scanner := bufio.NewScanner(fileContent)
for scanner.Scan() {
line := strings.TrimSpace(scanner.Text())
// Skip any comments.
if strings.HasPrefix(line, "#") {
continue
}
// Parse the name.
if strings.HasPrefix(line, "Candidate:") {
vulnerability.Name = strings.TrimSpace(strings.TrimPrefix(line, "Candidate:"))
vulnerability.Link = fmt.Sprintf(cveURL, vulnerability.Name)
continue
}
// Parse the priority.
if strings.HasPrefix(line, "Priority:") {
priority := strings.TrimSpace(strings.TrimPrefix(line, "Priority:"))
// Handle syntax error: Priority: medium (heap-protector)
if strings.Contains(priority, " ") {
priority = priority[:strings.Index(priority, " ")]
}
vulnerability.Severity = SeverityFromPriority(priority)
continue
}
// Parse the description.
if strings.HasPrefix(line, "Description:") {
readingDescription = true
vulnerability.Description = strings.TrimSpace(strings.TrimPrefix(line, "Description:")) // In case there is a formatting error and the description starts on the same line
continue
}
if readingDescription {
if strings.HasPrefix(line, "Ubuntu-Description:") || strings.HasPrefix(line, "Notes:") || strings.HasPrefix(line, "Bugs:") || strings.HasPrefix(line, "Priority:") || strings.HasPrefix(line, "Discovered-by:") || strings.HasPrefix(line, "Assigned-to:") {
readingDescription = false
} else {
vulnerability.Description = vulnerability.Description + " " + line
continue
}
}
// Try to parse the package that the vulnerability affects.
affectsCaptureArr := affectsCaptureRegexp.FindAllStringSubmatch(line, -1)
if len(affectsCaptureArr) > 0 {
affectsCapture := affectsCaptureArr[0]
md := map[string]string{}
for i, n := range affectsCapture {
md[affectsCaptureRegexpNames[i]] = strings.TrimSpace(n)
}
// Ignore Linux kernels.
if strings.HasPrefix(md["package"], "linux") {
continue
}
// Only consider the package if its status is needed, active, deferred, not-affected or
// released. Ignore DNE (package does not exist), needs-triage, ignored, pending.
if md["status"] == "needed" || md["status"] == "active" || md["status"] == "deferred" || md["status"] == "released" || md["status"] == "not-affected" {
md["release"] = strings.Split(md["release"], "/")[0]
if _, isReleaseIgnored := ubuntuIgnoredReleases[md["release"]]; isReleaseIgnored {
continue
}
if _, isReleaseKnown := database.UbuntuReleasesMapping[md["release"]]; !isReleaseKnown {
unknownReleases[md["release"]] = struct{}{}
continue
}
var version string
if md["status"] == "released" {
if md["note"] != "" {
var err error
err = versionfmt.Valid(dpkg.ParserName, md["note"])
if err != nil {
log.WithError(err).WithField("version", md["note"]).Warning("could not parse package version. skipping")
}
version = md["note"]
}
} else if md["status"] == "not-affected" {
version = versionfmt.MinVersion
} else {
version = versionfmt.MaxVersion
}
if version == "" {
continue
}
// Create and add the new package.
featureVersion := database.FeatureVersion{
Feature: database.Feature{
Namespace: database.Namespace{
Name: "ubuntu:" + database.UbuntuReleasesMapping[md["release"]],
VersionFormat: dpkg.ParserName,
},
Name: md["package"],
},
Version: version,
}
vulnerability.FixedIn = append(vulnerability.FixedIn, featureVersion)
}
}
}
// Trim extra spaces in the description
vulnerability.Description = strings.TrimSpace(vulnerability.Description)
// If no link has been provided (CVE-2006-NNN0 for instance), add the link to the tracker
if vulnerability.Link == "" {
vulnerability.Link = trackerGitURL
}
// If no priority has been provided (CVE-2007-0667 for instance), set the priority to Unknown
if vulnerability.Severity == "" {
vulnerability.Severity = database.UnknownSeverity
}
return
}
// SeverityFromPriority converts an priority from the Ubuntu CVE Tracker into
// a database.Severity.
func SeverityFromPriority(priority string) database.Severity {
switch priority {
case "untriaged":
return database.UnknownSeverity
case "negligible":
return database.NegligibleSeverity
case "low":
return database.LowSeverity
case "medium":
return database.MediumSeverity
case "high":
return database.HighSeverity
case "critical":
return database.CriticalSeverity
default:
log.Warningf("could not determine a vulnerability severity from: %s", priority)
return database.UnknownSeverity
}
}