trust.go

package trust

import (
	"bufio"
	"bytes"
	"encoding/base64"
	"encoding/json"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"github.com/containers/image/v5/types"
	"github.com/docker/docker/pkg/homedir"
	"github.com/ghodss/yaml"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
)

// PolicyContent struct for policy.json file
type PolicyContent struct {
	Default    []RepoContent     `json:"default"`
	Transports TransportsContent `json:"transports"`
}

// RepoContent struct used under each repo
type RepoContent struct {
	Type           string          `json:"type"`
	KeyType        string          `json:"keyType,omitempty"`
	KeyPath        string          `json:"keyPath,omitempty"`
	KeyData        string          `json:"keyData,omitempty"`
	SignedIdentity json.RawMessage `json:"signedIdentity,omitempty"`
}

// RepoMap map repo name to policycontent for each repo
type RepoMap map[string][]RepoContent

// TransportsContent struct for content under "transports"
type TransportsContent map[string]RepoMap

// RegistryConfiguration is one of the files in registriesDirPath configuring lookaside locations, or the result of merging them all.
// NOTE: Keep this in sync with docs/registries.d.md!
type RegistryConfiguration struct {
	DefaultDocker *RegistryNamespace `json:"default-docker"`
	// The key is a namespace, using fully-expanded Docker reference format or parent namespaces (per dockerReference.PolicyConfiguration*),
	Docker map[string]RegistryNamespace `json:"docker"`
}

// RegistryNamespace defines lookaside locations for a single namespace.
type RegistryNamespace struct {
	SigStore        string `json:"sigstore"`         // For reading, and if SigStoreStaging is not present, for writing.
	SigStoreStaging string `json:"sigstore-staging"` // For writing only.
}

// ShowOutput keep the fields for image trust show command
type ShowOutput struct {
	Repo      string
	Trusttype string
	GPGid     string
	Sigstore  string
}

// systemRegistriesDirPath is the path to registries.d.
const systemRegistriesDirPath = "/etc/containers/registries.d"

// userRegistriesDir is the path to the per user registries.d.
var userRegistriesDir = filepath.FromSlash(".config/containers/registries.d")

// DefaultPolicyPath returns a path to the default policy of the system.
func DefaultPolicyPath(sys *types.SystemContext) string {
	systemDefaultPolicyPath := "/etc/containers/policy.json"
	if sys != nil {
		if sys.SignaturePolicyPath != "" {
			return sys.SignaturePolicyPath
		}
		if sys.RootForImplicitAbsolutePaths != "" {
			return filepath.Join(sys.RootForImplicitAbsolutePaths, systemDefaultPolicyPath)
		}
	}
	return systemDefaultPolicyPath
}

// RegistriesDirPath returns a path to registries.d
func RegistriesDirPath(sys *types.SystemContext) string {
	if sys != nil && sys.RegistriesDirPath != "" {
		return sys.RegistriesDirPath
	}
	userRegistriesDirPath := filepath.Join(homedir.Get(), userRegistriesDir)
	if _, err := os.Stat(userRegistriesDirPath); err == nil {
		return userRegistriesDirPath
	}
	if sys != nil && sys.RootForImplicitAbsolutePaths != "" {
		return filepath.Join(sys.RootForImplicitAbsolutePaths, systemRegistriesDirPath)
	}

	return systemRegistriesDirPath
}

// LoadAndMergeConfig loads configuration files in dirPath
func LoadAndMergeConfig(dirPath string) (*RegistryConfiguration, error) {
	mergedConfig := RegistryConfiguration{Docker: map[string]RegistryNamespace{}}
	dockerDefaultMergedFrom := ""
	nsMergedFrom := map[string]string{}

	dir, err := os.Open(dirPath)
	if err != nil {
		if os.IsNotExist(err) {
			return &mergedConfig, nil
		}
		return nil, err
	}
	configNames, err := dir.Readdirnames(0)
	if err != nil {
		return nil, err
	}
	for _, configName := range configNames {
		if !strings.HasSuffix(configName, ".yaml") {
			continue
		}
		configPath := filepath.Join(dirPath, configName)
		configBytes, err := ioutil.ReadFile(configPath)
		if err != nil {
			return nil, err
		}
		var config RegistryConfiguration
		err = yaml.Unmarshal(configBytes, &config)
		if err != nil {
			return nil, errors.Wrapf(err, "error parsing %s", configPath)
		}
		if config.DefaultDocker != nil {
			if mergedConfig.DefaultDocker != nil {
				return nil, errors.Errorf(`Error parsing signature storage configuration: "default-docker" defined both in "%s" and "%s"`,
					dockerDefaultMergedFrom, configPath)
			}
			mergedConfig.DefaultDocker = config.DefaultDocker
			dockerDefaultMergedFrom = configPath
		}
		for nsName, nsConfig := range config.Docker { // includes config.Docker == nil
			if _, ok := mergedConfig.Docker[nsName]; ok {
				return nil, errors.Errorf(`Error parsing signature storage configuration: "docker" namespace "%s" defined both in "%s" and "%s"`,
					nsName, nsMergedFrom[nsName], configPath)
			}
			mergedConfig.Docker[nsName] = nsConfig
			nsMergedFrom[nsName] = configPath
		}
	}
	return &mergedConfig, nil
}

// HaveMatchRegistry checks if trust settings for the registry have been configured in yaml file
func HaveMatchRegistry(key string, registryConfigs *RegistryConfiguration) *RegistryNamespace {
	searchKey := key
	if !strings.Contains(searchKey, "/") {
		val, exists := registryConfigs.Docker[searchKey]
		if exists {
			return &val
		}
	}
	for range strings.Split(key, "/") {
		val, exists := registryConfigs.Docker[searchKey]
		if exists {
			return &val
		}
		if strings.Contains(searchKey, "/") {
			searchKey = searchKey[:strings.LastIndex(searchKey, "/")]
		}
	}
	return registryConfigs.DefaultDocker
}

// CreateTmpFile creates a temp file under dir and writes the content into it
func CreateTmpFile(dir, pattern string, content []byte) (string, error) {
	tmpfile, err := ioutil.TempFile(dir, pattern)
	if err != nil {
		return "", err
	}
	defer tmpfile.Close()

	if _, err := tmpfile.Write(content); err != nil {
		return "", err
	}
	return tmpfile.Name(), nil
}

// GetGPGIdFromKeyPath return user keyring from key path
func GetGPGIdFromKeyPath(path string) []string {
	cmd := exec.Command("gpg2", "--with-colons", path)
	results, err := cmd.Output()
	if err != nil {
		logrus.Errorf("error getting key identity: %s", err)
		return nil
	}
	return parseUids(results)
}

// GetGPGIdFromKeyData return user keyring from keydata
func GetGPGIdFromKeyData(key string) []string {
	decodeKey, err := base64.StdEncoding.DecodeString(key)
	if err != nil {
		logrus.Errorf("%s, error decoding key data", err)
		return nil
	}
	tmpfileName, err := CreateTmpFile("", "", decodeKey)
	if err != nil {
		logrus.Errorf("error creating key date temp file %s", err)
	}
	defer os.Remove(tmpfileName)
	return GetGPGIdFromKeyPath(tmpfileName)
}

func parseUids(colonDelimitKeys []byte) []string {
	var parseduids []string
	scanner := bufio.NewScanner(bytes.NewReader(colonDelimitKeys))
	for scanner.Scan() {
		line := scanner.Text()
		if strings.HasPrefix(line, "uid:") || strings.HasPrefix(line, "pub:") {
			uid := strings.Split(line, ":")[9]
			if uid == "" {
				continue
			}
			parseduid := uid
			if strings.Contains(uid, "<") && strings.Contains(uid, ">") {
				parseduid = strings.SplitN(strings.SplitAfterN(uid, "<", 2)[1], ">", 2)[0]
			}
			parseduids = append(parseduids, parseduid)
		}
	}
	return parseduids
}

// GetPolicy parse policy.json into PolicyContent struct
func GetPolicy(policyPath string) (PolicyContent, error) {
	var policyContentStruct PolicyContent
	policyContent, err := ioutil.ReadFile(policyPath)
	if err != nil {
		return policyContentStruct, errors.Wrap(err, "unable to read policy file")
	}
	if err := json.Unmarshal(policyContent, &policyContentStruct); err != nil {
		return policyContentStruct, errors.Wrapf(err, "could not parse trust policies from %s", policyPath)
	}
	return policyContentStruct, nil
}