feat(admin): add device credential isolation

2026-08-04 20:57:33 +08:00
parent 41881e81f3
commit 66355a7f89
20 changed files with 1745 additions and 87 deletions
@@ -0,0 +1,168 @@
+// Package deviceauth owns the machine identity boundary shared by all device routes.
+package deviceauth
+
+import (
+	"crypto/sha256"
+	"crypto/subtle"
+	"database/sql"
+	"encoding/hex"
+	"errors"
+	"net/http"
+	"strings"
+)
+
+const (
+	AuthorizationHeader = "Authorization"
+	DeviceIDHeader      = "X-CMBuyer-Device-ID"
+	tokenHexLength      = 64
+)
+
+var (
+	// ErrUnauthenticated deliberately covers every credential defect. Callers must not reveal
+	// whether a device exists, is revoked, or supplied a mismatched token.
+	ErrUnauthenticated = errors.New("device authentication failed")
+	// ErrUnavailable is distinct so a storage outage is not disguised as a bad credential.
+	// HTTP callers still return no diagnostic body because database details are server-only.
+	ErrUnavailable = errors.New("device authentication unavailable")
+)
+
+type Principal struct {
+	ID string
+}
+
+type Authenticator interface {
+	Authenticate(*http.Request) (Principal, error)
+}
+
+// RejectAllAuthenticator is useful for tests and for fail-closed wiring where no credential
+// store is available. Production startup uses SQLiteAuthenticator.
+type RejectAllAuthenticator struct{}
+
+func (RejectAllAuthenticator) Authenticate(*http.Request) (Principal, error) {
+	return Principal{}, ErrUnauthenticated
+}
+
+type SQLiteAuthenticator struct {
+	database *sql.DB
+}
+
+func NewSQLiteAuthenticator(database *sql.DB) (*SQLiteAuthenticator, error) {
+	if database == nil {
+		return nil, errors.New("device credential database is required")
+	}
+	if _, err := database.Exec("SELECT device_id FROM device_credentials LIMIT 1"); err != nil {
+		return nil, errors.New("device credential migration is not available")
+	}
+	return &SQLiteAuthenticator{database: database}, nil
+}
+
+func (authenticator *SQLiteAuthenticator) Authenticate(request *http.Request) (Principal, error) {
+	if request == nil {
+		return Principal{}, ErrUnauthenticated
+	}
+	deviceID, token, ok := requestCredentials(request)
+	if !ok {
+		return Principal{}, ErrUnauthenticated
+	}
+
+	candidateHash := sha256.Sum256(token)
+	var storedHash []byte
+	var hashType string
+	var hashLength sql.NullInt64
+	var status sql.NullString
+	var revokedAt sql.NullString
+	var found bool
+	err := authenticator.database.QueryRowContext(
+		request.Context(),
+		`SELECT CASE WHEN credentials.device_id IS NULL THEN zeroblob(32) ELSE credentials.token_sha256 END,
+		        typeof(credentials.token_sha256),
+		        length(credentials.token_sha256),
+		        credentials.status,
+		        credentials.revoked_at,
+		        credentials.device_id IS NOT NULL
+		 FROM (SELECT 1) AS singleton
+		 LEFT JOIN device_credentials AS credentials ON credentials.device_id = ?`,
+		deviceID,
+	).Scan(&storedHash, &hashType, &hashLength, &status, &revokedAt, &found)
+	if err != nil {
+		return Principal{}, ErrUnavailable
+	}
+	if len(storedHash) != sha256.Size {
+		return Principal{}, ErrUnavailable
+	}
+	matched := subtle.ConstantTimeCompare(candidateHash[:], storedHash) == 1
+	if !found {
+		// The LEFT JOIN supplies a 32-byte dummy hash, so unknown ids take the same compare path
+		// as known credentials without requiring a plaintext token lookup.
+		return Principal{}, ErrUnauthenticated
+	}
+	if hashType != "blob" || !hashLength.Valid || hashLength.Int64 != sha256.Size || len(storedHash) != sha256.Size || !status.Valid {
+		return Principal{}, ErrUnavailable
+	}
+	switch status.String {
+	case StatusActive:
+		if revokedAt.Valid {
+			return Principal{}, ErrUnavailable
+		}
+	case StatusRevoked:
+		if !revokedAt.Valid {
+			return Principal{}, ErrUnavailable
+		}
+		if _, err := parseStoredTime(revokedAt.String); err != nil {
+			return Principal{}, ErrUnavailable
+		}
+	default:
+		return Principal{}, ErrUnavailable
+	}
+	if !matched || status.String == StatusRevoked {
+		return Principal{}, ErrUnauthenticated
+	}
+	return Principal{ID: deviceID}, nil
+}
+
+func requestCredentials(request *http.Request) (string, []byte, bool) {
+	authorizations := request.Header.Values(AuthorizationHeader)
+	deviceIDs := request.Header.Values(DeviceIDHeader)
+	if len(authorizations) != 1 || len(deviceIDs) != 1 {
+		return "", nil, false
+	}
+	authorization := authorizations[0]
+	if len(authorization) != len("Bearer ")+tokenHexLength || !strings.EqualFold(authorization[:len("Bearer")], "Bearer") || authorization[len("Bearer")] != ' ' {
+		return "", nil, false
+	}
+	tokenHex := authorization[len("Bearer "):]
+	if !validLowerHex(tokenHex, tokenHexLength) || !ValidDeviceID(deviceIDs[0]) {
+		return "", nil, false
+	}
+	token, err := hex.DecodeString(tokenHex)
+	if err != nil {
+		return "", nil, false
+	}
+	return deviceIDs[0], token, true
+}
+
+func ValidDeviceID(value string) bool {
+	if len(value) != 36 {
+		return false
+	}
+	for index, character := range value {
+		if index == 8 || index == 13 || index == 18 || index == 23 {
+			if character != '-' {
+				return false
+			}
+			continue
+		}
+		if !(character >= '0' && character <= '9' || character >= 'a' && character <= 'f') {
+			return false
+		}
+	}
+	return value[14] == '4' && (value[19] == '8' || value[19] == '9' || value[19] == 'a' || value[19] == 'b')
+}
+
+func validLowerHex(value string, length int) bool {
+	if len(value) != length {
+		return false
+	}
+	decoded, err := hex.DecodeString(value)
+	return err == nil && hex.EncodeToString(decoded) == value
+}