go/secretsmgr: add support for ACME certificate issuance
This commit is contained in:
parent
b0d2782369
commit
037c6f0fd8
1 changed files with 338 additions and 4 deletions
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@ -4,19 +4,30 @@ import (
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"bufio"
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"bytes"
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"context"
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"crypto/x509"
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"encoding/json"
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"encoding/pem"
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"errors"
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"flag"
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"fmt"
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"io"
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"io/fs"
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"os"
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"os/exec"
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"os/user"
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"path/filepath"
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"regexp"
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"sort"
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"strconv"
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"strings"
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"syscall"
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"time"
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"github.com/coreos/go-systemd/v22/dbus"
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log "github.com/golang/glog"
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vapi "github.com/hashicorp/vault/api"
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"golang.org/x/crypto/ssh"
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"golang.org/x/sys/unix"
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)
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var (
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@ -25,10 +36,13 @@ var (
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sshHostKeyRole = flag.String("ssh_host_key_role", hostname(), "Role to use for signing SSH host keys")
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sshHostKeyPrincipals = flag.String("ssh_host_key_principals", defaultPrincipals(hostname()), "Principals to use for SSH host key certificate")
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sshHostKeyExpiryThreshold = flag.Duration("ssh_host_key_expiry_threshold", 3*24*time.Hour, "Expiry threshold for SSH host key")
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sshHostKeyOutputDir = flag.String("ssh_host_key_output_dir", "/var/lib/secretsmgr/ssh", "Path to SSH host key output dir")
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sshd = flag.String("sshd", "sshd", "Path to sshd")
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acmeCertificatesConfig = flag.String("acme_certificates_config", "", "Path to ACME certificates config")
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acmeCertificatesMount = flag.String("acme_certificates_mount", "acme", "Path that ACME is mounted at")
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acmeCertificatesExpiryThreshold = flag.Duration("acme_certificates_expiry_threshold", 31*24*time.Hour, "Expiry threshold for ACME certificates")
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acmeCertificatesForceRenew = flag.Bool("acme_certificates_force_renew", false, "Ignore remaining time and force ACME certificate renewal")
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)
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func hostname() string {
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@ -64,6 +78,71 @@ func sshHostKeyPaths(ctx context.Context) ([]string, error) {
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return keys, nil
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}
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type acmeCertificate struct {
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Role string `json:"role"`
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OutputName string `json:"output_name"`
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Hostnames []string `json:"hostnames"`
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UnitsToReloadOrRestart []string `json:"units_to_reload_or_restart"`
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Group string `json:"group"`
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}
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func (c acmeCertificate) OutputDir() string {
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return filepath.Join("/var/lib/acme", c.OutputName)
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}
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func (c acmeCertificate) FullchainPath() string {
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return filepath.Join(c.OutputDir(), "fullchain.pem")
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}
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func (c acmeCertificate) ChainPath() string {
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return filepath.Join(c.OutputDir(), "chain.pem")
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}
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func (c acmeCertificate) PrivkeyPath() string {
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return filepath.Join(c.OutputDir(), "privkey.pem")
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}
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func (c acmeCertificate) SortedHostnames() []string {
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h := make([]string, len(c.Hostnames))
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copy(h, c.Hostnames)
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sort.Strings(h)
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return h
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}
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var acmeCertBits = regexp.MustCompile(`^(?P<role>[^/]+)/(?P<shortname>[^=]+)=(?P<hostnames>[^/]+)(?:/(?P<units>[^/]+))?$`)
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func splitDiscardEmpty(s string, sep string) []string {
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bits := strings.Split(s, sep)
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out := make([]string, 0, len(bits))
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for _, bit := range bits {
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bit = strings.TrimSpace(bit)
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if bit == "" {
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continue
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}
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out = append(out, bit)
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}
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return out
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}
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func parseACMECertificates() ([]acmeCertificate, error) {
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if *acmeCertificatesConfig == "" {
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return nil, nil
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}
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cfgFile, err := os.Open(*acmeCertificatesConfig)
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if err != nil {
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return nil, err
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}
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defer cfgFile.Close()
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var cs []acmeCertificate
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if err := json.NewDecoder(cfgFile).Decode(&cs); err != nil {
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return nil, err
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}
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return cs, nil
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}
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func readFile(p string) ([]byte, error) {
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f, err := os.Open(p)
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if err != nil {
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@ -233,8 +312,262 @@ func checkAndRenewSSHCertificates(ctx context.Context, c *vapi.Client) bool {
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return hadErr
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}
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func checkAndRenewACMECertificates(ctx context.Context, c *vapi.Client) bool {
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func setsSame(a, b []string) bool {
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s := map[string]int{}
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for _, v := range a {
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s[v]++
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}
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for _, v := range b {
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s[v]++
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}
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for _, n := range s {
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if n != 2 {
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return false
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}
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}
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return true
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}
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func getGroupID(groupName string) (int, error) {
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g, err := user.LookupGroup(groupName)
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if err != nil {
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return 0, fmt.Errorf("looking up group %q: %w", groupName, err)
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}
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gid, err := strconv.Atoi(g.Gid)
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if err != nil {
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return 0, fmt.Errorf("converting group %q to int: %w", g.Gid, err)
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}
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return gid, nil
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}
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func setGroup(groupName string) (func(), error) {
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if groupName == "" {
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return func() {}, nil
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}
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gid, err := getGroupID(groupName)
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if err != nil {
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return nil, err
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}
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origGid := unix.Getegid()
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unix.Setregid(-1, gid)
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return func() {
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unix.Setregid(-1, origGid)
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}, nil
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}
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func makeOrFixPermissionsOnDir(p string, permissions fs.FileMode, group string) error {
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outDirFi, err := os.Stat(p)
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if errors.Is(err, fs.ErrNotExist) {
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restoreGroup, err := setGroup(group)
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if err != nil {
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return fmt.Errorf("setting group to create outdir: %w", err)
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}
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defer restoreGroup()
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return os.Mkdir(p, permissions)
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} else if err != nil {
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return fmt.Errorf("stating output dir %q: %w", p, err)
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}
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if (outDirFi.Mode() & fs.ModePerm) != permissions {
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if err := os.Chmod(p, permissions); err != nil {
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return fmt.Errorf("chmodding output dir %q: %w", p, err)
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}
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}
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outDirStat, ok := outDirFi.Sys().(*syscall.Stat_t)
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if !ok {
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return fmt.Errorf("outDirFi isn't a stat_t, is a %T", outDirFi)
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}
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gid, err := getGroupID(group)
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if err != nil {
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return err
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}
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if outDirStat.Gid != uint32(gid) {
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if err := os.Chown(p, -1, gid); err != nil {
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return fmt.Errorf("chgrping output dir %q: %w", p, err)
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}
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}
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return nil
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}
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func shouldRenewACMECert(c acmeCertificate) (bool, error) {
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outDirFi, err := os.Stat(c.OutputDir())
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if errors.Is(err, fs.ErrNotExist) {
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return true, fmt.Errorf("output dir %q doesn't exist", c.OutputDir())
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} else if err != nil {
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return false, fmt.Errorf("stating output dir %q: %w", c.OutputDir(), err)
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}
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if !outDirFi.IsDir() {
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log.Warningf("output dir %q isn't a dir; deleting it")
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if err := os.Remove(c.OutputDir()); err != nil {
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return false, fmt.Errorf("couldn't remove non-dir in place of output dir %q: %w", c.OutputDir(), err)
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}
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return true, fmt.Errorf("output dir %q wasn't a dir")
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}
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// Check that all the output files exist.
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for _, f := range []string{c.FullchainPath(), c.ChainPath(), c.PrivkeyPath()} {
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if _, err := os.Stat(f); errors.Is(err, fs.ErrNotExist) {
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return true, fmt.Errorf("output file %q doesn't exist", f)
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} else if err != nil {
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return false, fmt.Errorf("stating output file %q: %w", f, err)
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}
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}
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fc, err := os.Open(c.FullchainPath())
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if err != nil {
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return true, fmt.Errorf("opening fullchain %q: %w", c.FullchainPath(), err)
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}
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defer fc.Close()
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fcBytes, err := io.ReadAll(fc)
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if err != nil {
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return true, fmt.Errorf("reading fullchain %q: %w", c.FullchainPath(), err)
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}
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fcB, _ := pem.Decode(fcBytes)
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if fcB == nil {
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return true, fmt.Errorf("fullchain %q contained non-PEM bits", c.FullchainPath())
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} else if fcB.Type != "CERTIFICATE" {
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return true, fmt.Errorf("fullchain %q contained non-CERTIFICATE PEM block %q", c.FullchainPath(), fcB.Type)
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}
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crt, err := x509.ParseCertificate(fcB.Bytes)
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if err != nil {
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return true, fmt.Errorf("fullchain %q wasn't parsable as x509", c.FullchainPath())
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}
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// Check that the certificate hasn't expired.
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now := time.Now()
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expiryThreshold := now.Add(*acmeCertificatesExpiryThreshold)
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log.Infof("certificate in %q expires at %v (%v from now); expiry cutoff is %v", c.FullchainPath(), crt.NotAfter, crt.NotAfter.Sub(now), expiryThreshold)
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if crt.NotAfter.Before(expiryThreshold) {
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return true, fmt.Errorf("certificate in %q expires at %v (%v from now); expiry cutoff is %v", c.FullchainPath(), crt.NotAfter, crt.NotAfter.Sub(now), expiryThreshold)
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}
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// Check that the hostnames match.
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if !setsSame(c.Hostnames, crt.DNSNames) {
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return true, fmt.Errorf("certificate DNSNames %q don't match wanted hostnames %q", crt.DNSNames, c.Hostnames)
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}
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if *acmeCertificatesForceRenew {
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return true, fmt.Errorf("force renew flag set")
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}
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return false, nil
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}
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func writeCertificate(certDef acmeCertificate, cert *vapi.Secret) error {
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restoreGroup, err := setGroup(certDef.Group)
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if err != nil {
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return fmt.Errorf("setting group to write output: %w", err)
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}
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defer restoreGroup()
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setFiles := []struct {
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name string
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content []byte
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perm fs.FileMode
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}{{
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name: certDef.FullchainPath(),
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content: []byte(cert.Data["cert"].(string)),
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perm: 0644,
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}, {
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name: certDef.ChainPath(),
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content: []byte(cert.Data["issuer_cert"].(string)),
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perm: 0644,
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}, {
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name: certDef.PrivkeyPath(),
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content: []byte(cert.Data["private_key"].(string)),
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perm: 0640,
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}}
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for _, sf := range setFiles {
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log.Infof("writing file %v mode %s", sf.name, sf.perm)
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os.Remove(sf.name) // optimistically try to remove the file, we don't care if it succeeds
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// if it doesn't, we'll error when we try to open it
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f, err := os.OpenFile(sf.name, os.O_WRONLY|os.O_CREATE|os.O_EXCL, sf.perm)
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if err != nil {
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return fmt.Errorf("opening %v: %w", sf.name, err)
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}
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if _, err := f.Write(sf.content); err != nil {
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f.Close()
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os.Remove(sf.name)
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return fmt.Errorf("writing %v: %w", sf.name, err)
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}
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if err := f.Close(); err != nil {
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return fmt.Errorf("closing %v: %w", sf.name, err)
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}
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}
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return nil
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}
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func checkAndRenewACMECertificates(ctx context.Context, c *vapi.Client) bool {
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certDefs, err := parseACMECertificates()
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if err != nil {
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log.Errorf("failed to parse certificates: %v", err)
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return true
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}
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log.Infof("acme certificate defs: %#v", certDefs)
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var hadErr bool
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for _, certDef := range certDefs {
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log.Infof("maybe issuing %v (role: %v) with hostnames %v into %v", certDef.OutputName, certDef.Role, certDef.Hostnames, certDef.OutputDir())
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if shouldRenew, err := shouldRenewACMECert(certDef); shouldRenew && err == nil {
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log.Infof("shouldRenewACMECert for %v returned true with no reason", certDef.OutputName)
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} else if shouldRenew {
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log.Infof("shouldRenewACMECert for %v returned true: %v", certDef.OutputName, err)
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} else if err != nil {
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log.Errorf("shouldRenewACMECert for %v returned false and an error: %v", certDef.OutputName, err)
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hadErr = true
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continue
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} else if !shouldRenew {
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log.Infof("shouldRenewACMECert for %v returned false", certDef.OutputName)
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continue
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}
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if err := makeOrFixPermissionsOnDir(certDef.OutputDir(), 0750, certDef.Group); err != nil {
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log.Errorf("creating/fixing dir %q: %w", certDef.OutputDir(), err)
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hadErr = true
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continue
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}
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// Issue certificate.
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names := certDef.SortedHostnames()
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commonName := names[0]
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names = names[1:]
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cert, err := c.Logical().Write(fmt.Sprintf("%s/certs/%s", *acmeCertificatesMount, certDef.Role), map[string]interface{}{
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"common_name": commonName,
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"alternative_names": strings.Join(names, ","),
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})
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if err != nil {
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log.Errorf("issuing %v (role: %v) with hostnames %v into %v: %v", certDef.OutputName, certDef.Role, certDef.Hostnames, certDef.OutputDir(), err)
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hadErr = true
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continue
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}
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// Write out certificate.
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if err := writeCertificate(certDef, cert); err != nil {
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log.Errorf("writing out certificate %v: %w", certDef.OutputName, err)
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hadErr = true
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continue
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}
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}
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return hadErr
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}
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func main() {
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@ -244,6 +577,7 @@ func main() {
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cfg.Address = "https://vault.int.lukegb.com"
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cfg.AgentAddress = "http://localhost:8200"
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cfg.MaxRetries = 0
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cfg.Timeout = 15 * time.Minute
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c, err := vapi.NewClient(cfg)
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if err != nil {
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log.Exitf("failed to create vault client: %v", err)
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