133 lines
3.5 KiB
Go
133 lines
3.5 KiB
Go
package token
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import (
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"bytes"
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"fmt"
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"os"
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"os/exec"
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"path/filepath"
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"runtime"
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"strings"
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"github.com/hashicorp/errwrap"
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)
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// ExternalTokenHelperPath takes the configured path to a helper and expands it to
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// a full absolute path that can be executed. As of 0.5, the default token
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// helper is internal, to avoid problems running in dev mode (see GH-850 and
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// GH-783), so special assumptions of prepending "vault token-" no longer
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// apply.
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//
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// As an additional result, only absolute paths are now allowed. Looking in the
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// path or a current directory for an arbitrary executable could allow someone
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// to switch the expected binary for one further up the path (or in the current
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// directory), potentially opening up execution of an arbitrary binary.
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func ExternalTokenHelperPath(path string) (string, error) {
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if !filepath.IsAbs(path) {
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var err error
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path, err = filepath.Abs(path)
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if err != nil {
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return "", err
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}
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}
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if _, err := os.Stat(path); err != nil {
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return "", fmt.Errorf("unknown error getting the external helper path")
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}
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return path, nil
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}
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var _ TokenHelper = (*ExternalTokenHelper)(nil)
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// ExternalTokenHelper is the struct that has all the logic for storing and retrieving
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// tokens from the token helper. The API for the helpers is simple: the
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// BinaryPath is executed within a shell with environment Env. The last argument
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// appended will be the operation, which is:
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//
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// * "get" - Read the value of the token and write it to stdout.
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// * "store" - Store the value of the token which is on stdin. Output
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// nothing.
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// * "erase" - Erase the contents stored. Output nothing.
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//
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// Any errors can be written on stdout. If the helper exits with a non-zero
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// exit code then the stderr will be made part of the error value.
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type ExternalTokenHelper struct {
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BinaryPath string
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Env []string
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}
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// Erase deletes the contents from the helper.
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func (h *ExternalTokenHelper) Erase() error {
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cmd, err := h.cmd("erase")
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if err != nil {
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return err
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}
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if output, err := cmd.CombinedOutput(); err != nil {
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return errwrap.Wrapf(fmt.Sprintf("%q: {{err}}", string(output)), err)
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}
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return nil
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}
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// Get gets the token value from the helper.
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func (h *ExternalTokenHelper) Get() (string, error) {
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var buf, stderr bytes.Buffer
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cmd, err := h.cmd("get")
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if err != nil {
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return "", err
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}
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cmd.Stdout = &buf
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cmd.Stderr = &stderr
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if err := cmd.Run(); err != nil {
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return "", errwrap.Wrapf(fmt.Sprintf("%q: {{err}}", stderr.String()), err)
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}
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return buf.String(), nil
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}
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// Store stores the token value into the helper.
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func (h *ExternalTokenHelper) Store(v string) error {
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buf := bytes.NewBufferString(v)
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cmd, err := h.cmd("store")
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if err != nil {
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return err
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}
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cmd.Stdin = buf
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if output, err := cmd.CombinedOutput(); err != nil {
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return errwrap.Wrapf(fmt.Sprintf("%q: {{err}}", string(output)), err)
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}
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return nil
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}
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func (h *ExternalTokenHelper) Path() string {
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return h.BinaryPath
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}
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func (h *ExternalTokenHelper) cmd(op string) (*exec.Cmd, error) {
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script := strings.Replace(h.BinaryPath, "\\", "\\\\", -1) + " " + op
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cmd, err := ExecScript(script)
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if err != nil {
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return nil, err
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}
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cmd.Env = h.Env
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return cmd, nil
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}
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// ExecScript returns a command to execute a script
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func ExecScript(script string) (*exec.Cmd, error) {
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var shell, flag string
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if runtime.GOOS == "windows" {
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shell = "cmd"
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flag = "/C"
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} else {
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shell = "/bin/sh"
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flag = "-c"
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}
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if other := os.Getenv("SHELL"); other != "" {
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shell = other
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}
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cmd := exec.Command(shell, flag, script)
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return cmd, nil
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}
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