Do not leave the key store world-readable

SQLite creates its file with the process umask, which on a stock system means
every account on the machine can read it. What is in there is not a working
credential — keys are stored hashed — but it is the whole tenancy tree and
every request anyone made, and that should not depend on an operator
remembering to chmod it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/store/sqlite.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"os"
 	"slices"
 	"strings"
 	"time"
@@ -44,6 +45,17 @@ func OpenSQLite(ctx context.Context, path string) (*SQLite, error) {
 		_ = db.Close()
 		return nil, err
 	}
+	// SQLite creates the file with the process umask, which on a stock system
+	// means world-readable. What is in here is not a working credential — keys
+	// are stored hashed — but it is the whole tenancy tree and every request
+	// anyone made, and that should not be readable by every account on the
+	// machine because nobody remembered to chmod it.
+	for _, f := range []string{path, path + "-wal", path + "-shm"} {
+		if err := os.Chmod(f, 0o600); err != nil && !os.IsNotExist(err) {
+			_ = db.Close()
+			return nil, fmt.Errorf("securing %s: %w", f, err)
+		}
+	}
 	return &SQLite{db: db}, nil
 }
 

internal/store/store_test.go

@@ -3,6 +3,7 @@ package store
 import (
 	"context"
 	"errors"
+	"os"
 	"path/filepath"
 	"slices"
 	"strings"
@@ -403,3 +404,33 @@ func must(t *testing.T, err error) {
 		t.Fatal(err)
 	}
 }
+
+func TestTheStoreIsNotWorldReadable(t *testing.T) {
+	// SQLite creates the file with the process umask, which on a stock system
+	// leaves it readable by every account on the machine. What is in here is
+	// not a working credential, but it is the whole tenancy tree and every
+	// request anyone made.
+	dir := t.TempDir()
+	path := filepath.Join(dir, "llmgw.db")
+	s, err := OpenSQLite(context.Background(), path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer s.Close()
+
+	// Force the WAL files into existence.
+	tree(t, s)
+
+	for _, name := range []string{"llmgw.db", "llmgw.db-wal", "llmgw.db-shm"} {
+		info, err := os.Stat(filepath.Join(dir, name))
+		if os.IsNotExist(err) {
+			continue
+		}
+		if err != nil {
+			t.Fatal(err)
+		}
+		if mode := info.Mode().Perm(); mode&0o077 != 0 {
+			t.Errorf("%s is mode %o", name, mode)
+		}
+	}
+}