Skip to content
Snippets Groups Projects
Select Git revision
1 result Searching

signer.go

Blame
  • signer.go 2.72 KiB
    package signer
    
    import (
    	"crypto/md5"
    	"crypto/rand"
    	"fmt"
    	"log"
    	"strings"
    	"time"
    
    	"go4.org/wkfs"
    	_ "go4.org/wkfs/gcs" // Register "/gcs/" as a wkfs.
    
    	"github.com/nsheridan/cashier/lib"
    	"github.com/nsheridan/cashier/server/config"
    	"golang.org/x/crypto/ssh"
    )
    
    // KeySigner does the work of signing a ssh public key with the CA key.
    type KeySigner struct {
    	ca          ssh.Signer
    	validity    time.Duration
    	principals  []string
    	permissions map[string]string
    }
    
    // SignUserKey returns a signed ssh certificate.
    func (s *KeySigner) SignUserKey(req *lib.SignRequest) (*ssh.Certificate, error) {
    	pubkey, _, _, _, err := ssh.ParseAuthorizedKey([]byte(req.Key))
    	if err != nil {
    		return nil, err
    	}
    	expires := time.Now().UTC().Add(s.validity)
    	if req.ValidUntil.After(expires) {
    		req.ValidUntil = expires
    	}
    	cert := &ssh.Certificate{
    		CertType:    ssh.UserCert,
    		Key:         pubkey,
    		KeyId:       fmt.Sprintf("%s_%d", req.Principal, time.Now().UTC().Unix()),
    		ValidBefore: uint64(req.ValidUntil.Unix()),
    		ValidAfter:  uint64(time.Now().UTC().Add(-5 * time.Minute).Unix()),
    	}
    	cert.ValidPrincipals = append(cert.ValidPrincipals, req.Principal)
    	cert.ValidPrincipals = append(cert.ValidPrincipals, s.principals...)
    	cert.Extensions = s.permissions
    	if err := cert.SignCert(rand.Reader, s.ca); err != nil {
    		return nil, err
    	}
    	log.Printf("Issued cert id: %s principals: %s fp: %s valid until: %s\n", cert.KeyId, cert.ValidPrincipals, fingerprint(pubkey), time.Unix(int64(cert.ValidBefore), 0).UTC())
    	return cert, nil
    }
    
    func makeperms(perms []string) map[string]string {
    	if len(perms) > 0 {
    		m := make(map[string]string)
    		for _, p := range perms {
    			m[p] = ""
    		}
    		return m
    	}
    	return map[string]string{
    		"permit-X11-forwarding":   "",
    		"permit-agent-forwarding": "",
    		"permit-port-forwarding":  "",
    		"permit-pty":              "",
    		"permit-user-rc":          "",
    	}
    }