secret/internal/cli/root.go

package cli

import (
	"os"

	"github.com/awnumar/memguard"
	"github.com/spf13/cobra"
	"golang.org/x/sys/unix"
	"golang.org/x/term"
	"sneak.berlin/go/secret/internal/secret"
)

// Entry runs the secret CLI and returns the process exit code. It wipes
// every memguard buffer before it returns, so the caller must do nothing
// but exit with the code.
func Entry() int {
	raiseLockedMemoryLimit()

	// On SIGINT or SIGTERM memguard runs this function, wipes every buffer
	// and exits with status 1. The passphrase prompt turns echo off on the
	// controlling terminal until the read finishes, so a signal there would
	// leave echo off. Only a process in the terminal's foreground process
	// group may reset it: one in the background that tries is stopped
	// instead of exiting.
	terminal, terminalErr := os.Open(secret.TerminalPath)

	var terminalState *term.State

	if terminalErr == nil {
		defer func() { _ = terminal.Close() }()

		terminalState, terminalErr = term.GetState(int(terminal.Fd()))
	}

	memguard.CatchSignal(func(os.Signal) {
		if terminalErr != nil {
			return
		}

		foreground, err := unix.IoctlGetInt(int(terminal.Fd()), unix.TIOCGPGRP)
		if err == nil && foreground == unix.Getpgrp() {
			_ = term.Restore(int(terminal.Fd()), terminalState)
		}
	}, os.Interrupt, unix.SIGTERM)

	defer memguard.Purge()

	err := newRootCmd().Execute()
	if err != nil {
		return 1
	}

	return 0
}

// raiseLockedMemoryLimit raises this process's limit on locked memory, which
// holds every secret value, to the hard limit, the most a process may set
// without privileges. When that fails the limit stays as it was, and
// checkLockedMemoryLimit names it in its error.
func raiseLockedMemoryLimit() {
	var limit unix.Rlimit

	if unix.Getrlimit(unix.RLIMIT_MEMLOCK, &limit) == nil {
		limit.Cur = limit.Max
		_ = unix.Setrlimit(unix.RLIMIT_MEMLOCK, &limit)
	}
}

func newRootCmd() *cobra.Command {
	secret.Debug("newRootCmd starting")

	cmd := &cobra.Command{
		Use:   "secret",
		Short: "A simple secrets manager",
		Long: `A simple secrets manager to store and retrieve sensitive ` +
			`information securely.`,
		// Cobra prints the error a command returns; Entry does not.
		SilenceErrors: false,
		// Usage belongs only to a command called wrongly. Cobra has
		// checked its arguments and flag values before this runs, but
		// checks required flags (ValidateRequiredFlags) and flag groups
		// (ValidateFlagGroups) only after it, so both are checked here
		// to keep usage for them. An error after that comes from running
		// the command, and usage would only bury it. A subcommand that
		// sets its own PersistentPreRun replaces this one.
		PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
			err := cmd.ValidateRequiredFlags()
			if err != nil {
				return err
			}

			err = cmd.ValidateFlagGroups()
			if err != nil {
				return err
			}

			cmd.SilenceUsage = true

			return nil
		},
	}

	secret.Debug("Adding subcommands to root command")
	// Add subcommands
	cmd.AddCommand(NewInitCmd())
	cmd.AddCommand(newGenerateCmd())
	cmd.AddCommand(newVaultCmd())
	cmd.AddCommand(newAddCmd())
	cmd.AddCommand(newGetCmd())
	cmd.AddCommand(newListCmd())
	cmd.AddCommand(newRemoveCmd())
	cmd.AddCommand(newMoveCmd())
	cmd.AddCommand(newUnlockerCmd())
	cmd.AddCommand(newImportCmd())
	cmd.AddCommand(newEncryptCmd())
	cmd.AddCommand(newDecryptCmd())
	cmd.AddCommand(newVersionCmd())
	cmd.AddCommand(newInfoCmd())
	cmd.AddCommand(newCompletionCmd())

	secret.Debug("newRootCmd completed")

	return cmd
}