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loader.go
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loader.go
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package rule
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path"
"path/filepath"
"sort"
"strings"
"sync"
"time"
"github.com/evilsocket/opensnitch/daemon/conman"
"github.com/evilsocket/opensnitch/daemon/core"
"github.com/evilsocket/opensnitch/daemon/log"
"github.com/fsnotify/fsnotify"
)
// Loader is the object that holds the rules loaded from disk, as well as the
// rules watcher.
type Loader struct {
sync.RWMutex
path string
rules map[string]*Rule
rulesKeys []string
watcher *fsnotify.Watcher
liveReload bool
liveReloadRunning bool
}
// NewLoader loads rules from disk, and watches for changes made to the rules files
// on disk.
func NewLoader(liveReload bool) (*Loader, error) {
watcher, err := fsnotify.NewWatcher()
if err != nil {
return nil, err
}
return &Loader{
path: "",
rules: make(map[string]*Rule),
liveReload: liveReload,
watcher: watcher,
liveReloadRunning: false,
}, nil
}
// NumRules returns he number of loaded rules.
func (l *Loader) NumRules() int {
l.RLock()
defer l.RUnlock()
return len(l.rules)
}
// GetAll returns the loaded rules.
func (l *Loader) GetAll() map[string]*Rule {
l.RLock()
defer l.RUnlock()
return l.rules
}
// Load loads rules files from disk.
func (l *Loader) Load(path string) error {
if core.Exists(path) == false {
return fmt.Errorf("Path '%s' does not exist", path)
}
expr := filepath.Join(path, "*.json")
matches, err := filepath.Glob(expr)
if err != nil {
return fmt.Errorf("Error globbing '%s': %s", expr, err)
}
l.path = path
if len(l.rules) == 0 {
l.rules = make(map[string]*Rule)
}
for _, fileName := range matches {
log.Debug("Reading rule from %s", fileName)
if err := l.loadRule(fileName); err != nil {
log.Warning("%s", err)
continue
}
}
if l.liveReload && l.liveReloadRunning == false {
go l.liveReloadWorker()
}
return nil
}
func (l *Loader) loadRule(fileName string) error {
raw, err := ioutil.ReadFile(fileName)
if err != nil {
return fmt.Errorf("Error while reading %s: %s", fileName, err)
}
l.Lock()
defer l.Unlock()
var r Rule
err = json.Unmarshal(raw, &r)
if err != nil {
return fmt.Errorf("Error parsing rule from %s: %s", fileName, err)
}
raw = nil
if oldRule, found := l.rules[r.Name]; found {
l.cleanListsRule(oldRule)
}
if r.Enabled {
if err := r.Operator.Compile(); err != nil {
log.Warning("Operator.Compile() error: %s: %s", err, r.Operator.Data)
return fmt.Errorf("(1) Error compiling rule: %s", err)
}
if r.Operator.Type == List {
for i := 0; i < len(r.Operator.List); i++ {
if err := r.Operator.List[i].Compile(); err != nil {
log.Warning("Operator.Compile() error: %s: ", err)
return fmt.Errorf("(1) Error compiling list rule: %s", err)
}
}
}
}
if oldRule, found := l.rules[r.Name]; found {
l.deleteOldRuleFromDisk(oldRule, &r)
}
log.Debug("Loaded rule from %s: %s", fileName, r.String())
l.rules[r.Name] = &r
l.sortRules()
if l.isTemporary(&r) {
err = l.scheduleTemporaryRule(r)
}
return nil
}
// deleteRule deletes a rule from memory if it has been deleted from disk.
// This is only called if fsnotify's Remove event is fired, thus it doesn't
// have to delete temporary rules (!Always).
func (l *Loader) deleteRule(filePath string) {
fileName := filepath.Base(filePath)
ruleName := fileName[:len(fileName)-5]
l.RLock()
rule, found := l.rules[ruleName]
delRule := found && rule.Duration == Always
l.RUnlock()
if delRule {
l.Delete(ruleName)
}
}
func (l *Loader) deleteRuleFromDisk(ruleName string) error {
path := fmt.Sprint(l.path, "/", ruleName, ".json")
return os.Remove(path)
}
// deleteOldRuleFromDisk deletes a rule from disk if the Duration changes
// from Always (saved on disk), to !Always (temporary).
func (l *Loader) deleteOldRuleFromDisk(oldRule, newRule *Rule) {
if oldRule.Duration == Always && newRule.Duration != Always {
if err := l.deleteRuleFromDisk(oldRule.Name); err != nil {
log.Error("Error deleting old rule from disk: %s", oldRule.Name)
}
}
}
// cleanListsRule erases the list of domains of an Operator of type Lists
func (l *Loader) cleanListsRule(oldRule *Rule) {
if oldRule.Operator.Type == Lists {
oldRule.Operator.StopMonitoringLists()
} else if oldRule.Operator.Type == List {
for i := 0; i < len(oldRule.Operator.List); i++ {
if oldRule.Operator.List[i].Type == Lists {
oldRule.Operator.List[i].StopMonitoringLists()
break
}
}
}
}
func (l *Loader) liveReloadWorker() {
l.liveReloadRunning = true
log.Debug("Rules watcher started on path %s ...", l.path)
if err := l.watcher.Add(l.path); err != nil {
log.Error("Could not watch path: %s", err)
l.liveReloadRunning = false
return
}
for {
select {
case event := <-l.watcher.Events:
// a new rule json file has been created or updated
if event.Op&fsnotify.Write == fsnotify.Write {
if strings.HasSuffix(event.Name, ".json") {
log.Important("Ruleset changed due to %s, reloading ...", path.Base(event.Name))
if err := l.loadRule(event.Name); err != nil {
log.Warning("%s", err)
}
}
} else if event.Op&fsnotify.Remove == fsnotify.Remove {
if strings.HasSuffix(event.Name, ".json") {
log.Important("Rule deleted %s", path.Base(event.Name))
// we only need to delete from memory rules of type Always,
// because the Remove event is of a file, i.e.: Duration == Always
l.deleteRule(event.Name)
}
}
case err := <-l.watcher.Errors:
log.Error("File system watcher error: %s", err)
}
}
}
func (l *Loader) isTemporary(r *Rule) bool {
return r.Duration != Restart && r.Duration != Always && r.Duration != Once
}
func (l *Loader) isUniqueName(name string) bool {
_, found := l.rules[name]
return !found
}
func (l *Loader) setUniqueName(rule *Rule) {
l.Lock()
defer l.Unlock()
idx := 1
base := rule.Name
for l.isUniqueName(rule.Name) == false {
idx++
rule.Name = fmt.Sprintf("%s-%d", base, idx)
}
}
func (l *Loader) sortRules() {
l.rulesKeys = make([]string, 0, len(l.rules))
for k := range l.rules {
l.rulesKeys = append(l.rulesKeys, k)
}
sort.Strings(l.rulesKeys)
}
func (l *Loader) addUserRule(rule *Rule) {
if rule.Duration == Once {
return
}
l.setUniqueName(rule)
l.replaceUserRule(rule)
}
func (l *Loader) replaceUserRule(rule *Rule) (err error) {
l.Lock()
oldRule, found := l.rules[rule.Name]
l.Unlock()
if found {
// If the rule has changed from Always (saved on disk) to !Always (temporary),
// we need to delete the rule from disk and keep it in memory.
l.deleteOldRuleFromDisk(oldRule, rule)
// delete loaded lists, if this is a rule of type Lists
l.cleanListsRule(oldRule)
}
if rule.Enabled {
if err := rule.Operator.Compile(); err != nil {
log.Warning("Operator.Compile() error: %s: %s", err, rule.Operator.Data)
return fmt.Errorf("(2) Error compiling rule: %s", err)
}
if rule.Operator.Type == List {
// TODO: use List protobuf object instead of un/marshalling to/from json
if err = json.Unmarshal([]byte(rule.Operator.Data), &rule.Operator.List); err != nil {
return fmt.Errorf("Error loading rule of type list: %s", err)
}
for i := 0; i < len(rule.Operator.List); i++ {
if err := rule.Operator.List[i].Compile(); err != nil {
log.Warning("Operator.Compile() error: %s: ", err)
return fmt.Errorf("(2) Error compiling list rule: %s", err)
}
}
}
}
l.Lock()
l.rules[rule.Name] = rule
l.sortRules()
l.Unlock()
if l.isTemporary(rule) {
err = l.scheduleTemporaryRule(*rule)
}
return err
}
func (l *Loader) scheduleTemporaryRule(rule Rule) error {
tTime, err := time.ParseDuration(string(rule.Duration))
if err != nil {
return err
}
time.AfterFunc(tTime, func() {
l.Lock()
defer l.Unlock()
log.Info("Temporary rule expired: %s - %s", rule.Name, rule.Duration)
if newRule, found := l.rules[rule.Name]; found {
if newRule.Duration != rule.Duration {
log.Debug("%s temporary rule expired, but has new Duration, old: %s, new: %s", rule.Name, rule.Duration, newRule.Duration)
return
}
delete(l.rules, rule.Name)
l.sortRules()
}
})
return nil
}
// Add adds a rule to the list of rules, and optionally saves it to disk.
func (l *Loader) Add(rule *Rule, saveToDisk bool) error {
l.addUserRule(rule)
if saveToDisk {
fileName := filepath.Join(l.path, fmt.Sprintf("%s.json", rule.Name))
return l.Save(rule, fileName)
}
return nil
}
// Replace adds a rule to the list of rules, and optionally saves it to disk.
func (l *Loader) Replace(rule *Rule, saveToDisk bool) error {
if err := l.replaceUserRule(rule); err != nil {
return err
}
if saveToDisk {
l.Lock()
defer l.Unlock()
fileName := filepath.Join(l.path, fmt.Sprintf("%s.json", rule.Name))
return l.Save(rule, fileName)
}
return nil
}
// Save a rule to disk.
func (l *Loader) Save(rule *Rule, path string) error {
rule.Updated = time.Now()
raw, err := json.MarshalIndent(rule, "", " ")
if err != nil {
return fmt.Errorf("Error while saving rule %s to %s: %s", rule, path, err)
}
if err = ioutil.WriteFile(path, raw, 0644); err != nil {
return fmt.Errorf("Error while saving rule %s to %s: %s", rule, path, err)
}
return nil
}
// Delete deletes a rule from the list by name.
// If the duration is Always (i.e: saved on disk), it'll attempt to delete
// it from disk.
func (l *Loader) Delete(ruleName string) error {
l.Lock()
defer l.Unlock()
rule := l.rules[ruleName]
if rule == nil {
return nil
}
l.cleanListsRule(rule)
delete(l.rules, ruleName)
l.sortRules()
if rule.Duration != Always {
return nil
}
log.Info("Delete() rule: %s", rule)
return l.deleteRuleFromDisk(ruleName)
}
// FindFirstMatch will try match the connection against the existing rule set.
func (l *Loader) FindFirstMatch(con *conman.Connection) (match *Rule) {
l.RLock()
defer l.RUnlock()
for _, idx := range l.rulesKeys {
rule, _ := l.rules[idx]
if rule.Enabled == false {
continue
}
if rule.Match(con) {
// We have a match.
// Save the rule in order to don't ask the user to take action,
// and keep iterating until a Deny or a Priority rule appears.
match = rule
if rule.Action == Deny || rule.Precedence == true {
return rule
}
}
}
return match
}