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filter.go
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filter.go
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// SPDX-License-Identifier: Apache-2.0
// Copyright Authors of Cilium
package labelsfilter
import (
"encoding/json"
"fmt"
"os"
"regexp"
"strings"
k8sConst "github.com/cilium/cilium/pkg/k8s/apis/cilium.io"
"github.com/cilium/cilium/pkg/labels"
"github.com/cilium/cilium/pkg/lock"
"github.com/cilium/cilium/pkg/logging"
"github.com/cilium/cilium/pkg/logging/logfields"
)
var (
log = logging.DefaultLogger.WithField(logfields.LogSubsys, "labels-filter")
validLabelPrefixesMU lock.RWMutex
validLabelPrefixes *labelPrefixCfg // Label prefixes used to filter from all labels
)
const (
// LPCfgFileVersion represents the version of a Label Prefix Configuration File
LPCfgFileVersion = 1
// reservedLabelsPattern is the prefix pattern for all reserved labels
reservedLabelsPattern = labels.LabelSourceReserved + ":.*"
)
// LabelPrefix is the cilium's representation of a container label.
// +k8s:deepcopy-gen=false
// +k8s:openapi-gen=false
// +deepequal-gen=false
type LabelPrefix struct {
// Ignore if true will cause this prefix to be ignored insted of being accepted
Ignore bool `json:"invert"`
Prefix string `json:"prefix"`
Source string `json:"source"`
expr *regexp.Regexp
}
// String returns a human readable representation of the LabelPrefix
func (p LabelPrefix) String() string {
s := fmt.Sprintf("%s:%s", p.Source, p.Prefix)
if p.Ignore {
s = "!" + s
}
return s
}
// matches returns true and the length of the matched section if the label is
// matched by the LabelPrefix. The Ignore flag has no effect at this point.
func (p LabelPrefix) matches(l labels.Label) (bool, int) {
if p.Source != "" && p.Source != l.Source {
return false, 0
}
// If no regular expression is available, fall back to prefix matching
if p.expr == nil {
return strings.HasPrefix(l.Key, p.Prefix), len(p.Prefix)
}
res := p.expr.FindStringIndex(l.Key)
// No match if regexp was not found
if res == nil {
return false, 0
}
// Otherwise match if match was found at start of key
return res[0] == 0, res[1]
}
// parseLabelPrefix returns a LabelPrefix created from the string label parameter.
func parseLabelPrefix(label string) (*LabelPrefix, error) {
labelPrefix := LabelPrefix{}
i := strings.IndexByte(label, ':')
if i >= 0 {
labelPrefix.Source = label[:i]
labelPrefix.Prefix = label[i+1:]
} else {
labelPrefix.Prefix = label
}
if labelPrefix.Prefix[0] == '!' {
labelPrefix.Ignore = true
labelPrefix.Prefix = labelPrefix.Prefix[1:]
}
r, err := regexp.Compile(labelPrefix.Prefix)
if err != nil {
return nil, fmt.Errorf("unable to compile regexp: %s", err)
}
labelPrefix.expr = r
return &labelPrefix, nil
}
// ParseLabelPrefixCfg parses valid label prefixes from a file and from a slice
// of valid prefixes. Both are optional. If both are provided, both list are
// appended together.
func ParseLabelPrefixCfg(prefixes []string, file string) error {
var cfg *labelPrefixCfg
var err error
var fromCustomFile bool
// Use default label prefix if configuration file not provided
if file == "" {
log.Info("Parsing base label prefixes from default label list")
cfg = defaultLabelPrefixCfg()
} else {
log.Infof("Parsing base label prefixes from file %s", file)
cfg, err = readLabelPrefixCfgFrom(file)
if err != nil {
return fmt.Errorf("unable to read label prefix file: %s", err)
}
fromCustomFile = true
}
log.Infof("Parsing additional label prefixes from user inputs: %v", prefixes)
for _, label := range prefixes {
p, err := parseLabelPrefix(label)
if err != nil {
return err
}
if !p.Ignore {
cfg.whitelist = true
}
cfg.LabelPrefixes = append(cfg.LabelPrefixes, p)
}
if fromCustomFile {
found := false
for _, label := range cfg.LabelPrefixes {
if label.Source+":"+label.Prefix == reservedLabelsPattern {
found = true
break
}
}
if !found {
log.Errorf("'%s' needs to be included in the final label list for "+
"Cilium to work properly.", reservedLabelsPattern)
}
}
validLabelPrefixes = cfg
log.Info("Final label prefixes to be used for identity evaluation:")
for _, l := range validLabelPrefixes.LabelPrefixes {
log.Infof(" - %s", l)
}
return nil
}
// labelPrefixCfg is the label prefix configuration to filter labels of started
// containers.
// +k8s:openapi-gen=false
type labelPrefixCfg struct {
Version int `json:"version"`
LabelPrefixes []*LabelPrefix `json:"valid-prefixes"`
// whitelist if true, indicates that an inclusive rule has to match
// in order for the label to be considered
whitelist bool
}
// defaultLabelPrefixCfg returns a default LabelPrefixCfg using the latest
// LPCfgFileVersion
func defaultLabelPrefixCfg() *labelPrefixCfg {
cfg := &labelPrefixCfg{
Version: LPCfgFileVersion,
LabelPrefixes: []*LabelPrefix{},
}
expressions := []string{
reservedLabelsPattern, // include all reserved labels
regexp.QuoteMeta(k8sConst.PodNamespaceLabel), // include io.kubernetes.pod.namespace
regexp.QuoteMeta(k8sConst.PodNamespaceMetaLabels), // include all namespace labels
regexp.QuoteMeta(k8sConst.AppKubernetes), // include app.kubernetes.io
`!io\.kubernetes`, // ignore all other io.kubernetes labels
`!kubernetes\.io`, // ignore all other kubernetes.io labels
`!.*beta\.kubernetes\.io`, // ignore all beta.kubernetes.io labels
`!k8s\.io`, // ignore all k8s.io labels
`!pod-template-generation`, // ignore pod-template-generation
`!pod-template-hash`, // ignore pod-template-hash
`!controller-revision-hash`, // ignore controller-revision-hash
`!annotation.*`, // ignore all annotation labels
`!etcd_node`, // ignore etcd_node label
}
for _, e := range expressions {
p, err := parseLabelPrefix(e)
if err != nil {
msg := fmt.Sprintf("BUG: Unable to parse default label prefix '%s': %s", e, err)
panic(msg)
}
cfg.LabelPrefixes = append(cfg.LabelPrefixes, p)
}
return cfg
}
// readLabelPrefixCfgFrom reads a label prefix configuration file from fileName.
// return an error if fileName is empty, or if version is not supported.
func readLabelPrefixCfgFrom(fileName string) (*labelPrefixCfg, error) {
if fileName == "" {
return nil, fmt.Errorf("label prefix file not provided")
}
f, err := os.Open(fileName)
if err != nil {
return nil, err
}
defer f.Close()
lpc := labelPrefixCfg{}
err = json.NewDecoder(f).Decode(&lpc)
if err != nil {
return nil, err
}
if lpc.Version != LPCfgFileVersion {
return nil, fmt.Errorf("unsupported version %d", lpc.Version)
}
for _, lp := range lpc.LabelPrefixes {
if lp.Prefix == "" {
return nil, fmt.Errorf("invalid label prefix file: prefix was empty")
}
if lp.Source == "" {
return nil, fmt.Errorf("invalid label prefix file: source was empty")
}
if !lp.Ignore {
lpc.whitelist = true
}
}
return &lpc, nil
}
func (cfg *labelPrefixCfg) filterLabels(lbls labels.Labels) (identityLabels, informationLabels labels.Labels) {
if len(lbls) == 0 {
return nil, nil
}
validLabelPrefixesMU.RLock()
defer validLabelPrefixesMU.RUnlock()
identityLabels = labels.Labels{}
informationLabels = labels.Labels{}
for k, v := range lbls {
included, ignored := 0, 0
for _, p := range cfg.LabelPrefixes {
if m, len := p.matches(v); m {
if p.Ignore {
// save length of shortest matching ignore
if ignored == 0 || len < ignored {
ignored = len
}
} else {
// save length of longest matching include
if len > included {
included = len
}
}
}
}
// A label is accepted if :
// - No inclusive LabelPrefix (Ignore flag not set) is
// configured and label is not ignored.
// - An inclusive LabelPrefix matches the label
// - If both an inclusive and ignore LabelPrefix match, the
// label is accepted if the matching section in the label
// is greater than the ignored matching section in label,
// e.g. when evaluating the label foo.bar, the prefix rules
// {!foo, foo.bar} will cause the label to be accepted
// because the inclusive prefix matches over a longer section.
if (!cfg.whitelist && ignored == 0) || included > ignored {
// Just want to make sure we don't have labels deleted in
// on side and disappearing in the other side...
identityLabels[k] = v
} else {
informationLabels[k] = v
}
}
return identityLabels, informationLabels
}
// Filter returns Labels from the given labels that have the same source and the
// same prefix as one of lpc valid prefixes, as well as labels that do not match
// the aforementioned filtering criteria.
func Filter(lbls labels.Labels) (identityLabels, informationLabels labels.Labels) {
return validLabelPrefixes.filterLabels(lbls)
}