fix: correct verify's ciphertext field map against the models

backup/manifest.go

@@ -3,6 +3,7 @@ package backup
 import (
 	"errors"
 	"fmt"
+	"strings"
 	"time"
 )
 
@@ -16,6 +17,10 @@ const ManifestName = "manifest.json"
 // ErrUnknownFormat is returned for an archive this build cannot read.
 var ErrUnknownFormat = errors.New("unsupported archive format version")
 
+// ErrBadCollectionName is returned for a manifest naming a collection that
+// cannot safely be used as a path component.
+var ErrBadCollectionName = errors.New("manifest names an unusable collection")
+
 // CollectionEntry describes one collection in the archive. Bytes and SHA256
 // cover the uncompressed .bson member, which is what restore verifies before
 // writing anything.
@@ -49,6 +54,27 @@ func (m Manifest) Check() error {
 		return fmt.Errorf("%w: archive is version %d, this build reads version %d",
 			ErrUnknownFormat, m.FormatVersion, FormatVersion)
 	}
+	// Collection names become path components inside the extraction directory,
+	// and an archive is operator-supplied input that may not be one we wrote.
+	for _, c := range m.Collections {
+		if err := checkCollectionName(c.Name); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// checkCollectionName refuses a name that could escape a directory when joined
+// as a path component.
+func checkCollectionName(name string) error {
+	switch {
+	case name == "":
+		return fmt.Errorf("%w: a collection entry has no name", ErrBadCollectionName)
+	case name == "." || name == "..":
+		return fmt.Errorf("%w: %q", ErrBadCollectionName, name)
+	case strings.ContainsAny(name, "/\\"), strings.Contains(name, ".."):
+		return fmt.Errorf("%w: %q", ErrBadCollectionName, name)
+	}
 	return nil
 }
 
@@ -68,6 +94,9 @@ func (m Manifest) Collection(name string) (CollectionEntry, bool) {
 // match the archive, this is the list of what will be unreadable afterwards,
 // and an operator deserves to see it before the write rather than discover it
 // a week later.
+//
+// settings is not in the list: it holds no encrypted material. Its ESO read
+// token is a SHA-256 hash, not ciphertext.
 func CiphertextCollections() []string {
-	return []string{"keys", "secrets", "auth_providers", "console_sessions", "settings"}
+	return []string{"keys", "secrets", "auth_providers", "console_sessions"}
 }