cloudflare/cloudflared
Publicmirrored from https://github.com/cloudflare/cloudflaredAvailable
sshgen/sshgen.go
188lines · modecode
| 1 | package sshgen |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "crypto/ecdsa" |
| 6 | "crypto/elliptic" |
| 7 | "crypto/rand" |
| 8 | "crypto/x509" |
| 9 | "encoding/json" |
| 10 | "encoding/pem" |
| 11 | "errors" |
| 12 | "fmt" |
| 13 | "io" |
| 14 | "io/ioutil" |
| 15 | "net/http" |
| 16 | "net/url" |
| 17 | "time" |
| 18 | |
| 19 | "github.com/cloudflare/cloudflared/cmd/cloudflared/config" |
| 20 | cfpath "github.com/cloudflare/cloudflared/cmd/cloudflared/path" |
| 21 | "github.com/coreos/go-oidc/jose" |
| 22 | homedir "github.com/mitchellh/go-homedir" |
| 23 | gossh "golang.org/x/crypto/ssh" |
| 24 | ) |
| 25 | |
| 26 | const ( |
| 27 | signEndpoint = "/cdn-cgi/access/cert_sign" |
| 28 | keyName = "cf_key" |
| 29 | ) |
| 30 | |
| 31 | // signPayload represents the request body sent to the sign handler API |
| 32 | type signPayload struct { |
| 33 | PublicKey string `json:"public_key"` |
| 34 | JWT string `json:"jwt"` |
| 35 | Issuer string `json:"issuer"` |
| 36 | } |
| 37 | |
| 38 | // signResponse represents the response body from the sign handler API |
| 39 | type signResponse struct { |
| 40 | KeyID string `json:"id"` |
| 41 | Certificate string `json:"certificate"` |
| 42 | ExpiresAt time.Time `json:"expires_at"` |
| 43 | } |
| 44 | |
| 45 | // ErrorResponse struct stores error information after any error-prone function |
| 46 | type errorResponse struct { |
| 47 | Status int `json:"status"` |
| 48 | Message string `json:"message"` |
| 49 | } |
| 50 | |
| 51 | var mockRequest func(url, contentType string, body io.Reader) (*http.Response, error) = nil |
| 52 | |
| 53 | // GenerateShortLivedCertificate generates and stores a keypair for short lived certs |
| 54 | func GenerateShortLivedCertificate(appURL *url.URL, token string) error { |
| 55 | fullName, err := cfpath.GenerateFilePathFromURL(appURL, keyName) |
| 56 | if err != nil { |
| 57 | return err |
| 58 | } |
| 59 | |
| 60 | cert, err := handleCertificateGeneration(token, fullName) |
| 61 | if err != nil { |
| 62 | return err |
| 63 | } |
| 64 | |
| 65 | name := fullName + "-cert.pub" |
| 66 | if err := writeKey(name, []byte(cert)); err != nil { |
| 67 | return err |
| 68 | } |
| 69 | |
| 70 | return nil |
| 71 | } |
| 72 | |
| 73 | // handleCertificateGeneration takes a JWT and uses it build a signPayload |
| 74 | // to send to the Sign endpoint with the public key from the keypair it generated |
| 75 | func handleCertificateGeneration(token, fullName string) (string, error) { |
| 76 | if token == "" { |
| 77 | return "", errors.New("invalid token") |
| 78 | } |
| 79 | |
| 80 | jwt, err := jose.ParseJWT(token) |
| 81 | if err != nil { |
| 82 | return "", err |
| 83 | } |
| 84 | |
| 85 | claims, err := jwt.Claims() |
| 86 | if err != nil { |
| 87 | return "", err |
| 88 | } |
| 89 | |
| 90 | issuer, _, err := claims.StringClaim("iss") |
| 91 | if err != nil { |
| 92 | return "", err |
| 93 | } |
| 94 | |
| 95 | pub, err := generateKeyPair(fullName) |
| 96 | if err != nil { |
| 97 | return "", err |
| 98 | } |
| 99 | |
| 100 | buf, err := json.Marshal(&signPayload{ |
| 101 | PublicKey: string(pub), |
| 102 | JWT: token, |
| 103 | Issuer: issuer, |
| 104 | }) |
| 105 | if err != nil { |
| 106 | return "", err |
| 107 | } |
| 108 | |
| 109 | var res *http.Response |
| 110 | if mockRequest != nil { |
| 111 | res, err = mockRequest(issuer+signEndpoint, "application/json", bytes.NewBuffer(buf)) |
| 112 | } else { |
| 113 | res, err = http.Post(issuer+signEndpoint, "application/json", bytes.NewBuffer(buf)) |
| 114 | } |
| 115 | |
| 116 | if err != nil { |
| 117 | return "", err |
| 118 | } |
| 119 | defer res.Body.Close() |
| 120 | |
| 121 | decoder := json.NewDecoder(res.Body) |
| 122 | |
| 123 | if res.StatusCode != 200 { |
| 124 | var errResponse errorResponse |
| 125 | if err := decoder.Decode(&errResponse); err != nil { |
| 126 | return "", err |
| 127 | } |
| 128 | return "", fmt.Errorf("%d: %s", errResponse.Status, errResponse.Message) |
| 129 | } |
| 130 | |
| 131 | var signRes signResponse |
| 132 | if err := decoder.Decode(&signRes); err != nil { |
| 133 | return "", err |
| 134 | } |
| 135 | return signRes.Certificate, err |
| 136 | } |
| 137 | |
| 138 | // generateKeyPair creates a EC keypair (P256) and stores them in the homedir. |
| 139 | // returns the generated public key from the successful keypair generation |
| 140 | func generateKeyPair(fullName string) ([]byte, error) { |
| 141 | pubKeyName := fullName + ".pub" |
| 142 | |
| 143 | exist, err := config.FileExists(pubKeyName) |
| 144 | if err != nil { |
| 145 | return nil, err |
| 146 | } |
| 147 | if exist { |
| 148 | return ioutil.ReadFile(pubKeyName) |
| 149 | } |
| 150 | |
| 151 | key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader) |
| 152 | if err != nil { |
| 153 | return nil, err |
| 154 | } |
| 155 | parsed, err := x509.MarshalECPrivateKey(key) |
| 156 | if err != nil { |
| 157 | return nil, err |
| 158 | } |
| 159 | |
| 160 | if err := writeKey(fullName, pem.EncodeToMemory(&pem.Block{ |
| 161 | Type: "EC PRIVATE KEY", |
| 162 | Bytes: parsed, |
| 163 | })); err != nil { |
| 164 | return nil, err |
| 165 | } |
| 166 | |
| 167 | pub, err := gossh.NewPublicKey(&key.PublicKey) |
| 168 | if err != nil { |
| 169 | return nil, err |
| 170 | } |
| 171 | data := gossh.MarshalAuthorizedKey(pub) |
| 172 | |
| 173 | if err := writeKey(pubKeyName, data); err != nil { |
| 174 | return nil, err |
| 175 | } |
| 176 | |
| 177 | return data, nil |
| 178 | } |
| 179 | |
| 180 | // writeKey will write a key to disk in DER format (it's a standard pem key) |
| 181 | func writeKey(filename string, data []byte) error { |
| 182 | filepath, err := homedir.Expand(filename) |
| 183 | if err != nil { |
| 184 | return err |
| 185 | } |
| 186 | |
| 187 | return ioutil.WriteFile(filepath, data, 0600) |
| 188 | } |
| 189 | |