package ca import ( "bytes" "crypto/x509" "encoding/pem" "fmt" "io/ioutil" "net/http" "strings" "github.com/hashicorp/consul/agent/connect" "github.com/hashicorp/consul/agent/structs" vaultapi "github.com/hashicorp/vault/api" "github.com/mitchellh/mapstructure" ) const VaultCALeafCertRole = "leaf-cert" var ErrBackendNotMounted = fmt.Errorf("backend not mounted") var ErrBackendNotInitialized = fmt.Errorf("backend not initialized") type VaultProvider struct { config *structs.VaultCAProviderConfig client *vaultapi.Client isPrimary bool clusterID string spiffeID *connect.SpiffeIDSigning setupIntermediatePKIPathDone bool } func vaultTLSConfig(config *structs.VaultCAProviderConfig) *vaultapi.TLSConfig { return &vaultapi.TLSConfig{ CACert: config.CAFile, CAPath: config.CAPath, ClientCert: config.CertFile, ClientKey: config.KeyFile, Insecure: config.TLSSkipVerify, TLSServerName: config.TLSServerName, } } // Configure sets up the provider using the given configuration. func (v *VaultProvider) Configure(cfg ProviderConfig) error { config, err := ParseVaultCAConfig(cfg.RawConfig) if err != nil { return err } clientConf := &vaultapi.Config{ Address: config.Address, } err = clientConf.ConfigureTLS(vaultTLSConfig(config)) if err != nil { return err } client, err := vaultapi.NewClient(clientConf) if err != nil { return err } client.SetToken(config.Token) v.config = config v.client = client v.isPrimary = cfg.IsPrimary v.clusterID = cfg.ClusterID v.spiffeID = connect.SpiffeIDSigningForCluster(&structs.CAConfiguration{ClusterID: v.clusterID}) return nil } // State implements Provider. Vault provider needs no state other than the // user-provided config currently. func (v *VaultProvider) State() (map[string]string, error) { return nil, nil } // ActiveRoot returns the active root CA certificate. func (v *VaultProvider) ActiveRoot() (string, error) { return v.getCA(v.config.RootPKIPath) } // GenerateRoot mounts and initializes a new root PKI backend if needed. func (v *VaultProvider) GenerateRoot() error { if !v.isPrimary { return fmt.Errorf("provider is not the root certificate authority") } // Set up the root PKI backend if necessary. _, err := v.ActiveRoot() switch err { case ErrBackendNotMounted: err := v.client.Sys().Mount(v.config.RootPKIPath, &vaultapi.MountInput{ Type: "pki", Description: "root CA backend for Consul Connect", Config: vaultapi.MountConfigInput{ MaxLeaseTTL: "8760h", }, }) if err != nil { return err } fallthrough case ErrBackendNotInitialized: uid, err := connect.CompactUID() if err != nil { return err } _, err = v.client.Logical().Write(v.config.RootPKIPath+"root/generate/internal", map[string]interface{}{ "common_name": connect.CACN("vault", uid, v.clusterID, v.isPrimary), "uri_sans": v.spiffeID.URI().String(), "key_type": v.config.PrivateKeyType, "key_bits": v.config.PrivateKeyBits, }) if err != nil { return err } default: if err != nil { return err } } return nil } // GenerateIntermediateCSR creates a private key and generates a CSR // for another datacenter's root to sign, overwriting the intermediate backend // in the process. func (v *VaultProvider) GenerateIntermediateCSR() (string, error) { if v.isPrimary { return "", fmt.Errorf("provider is the root certificate authority, " + "cannot generate an intermediate CSR") } return v.generateIntermediateCSR() } func (v *VaultProvider) setupIntermediatePKIPath() error { if v.setupIntermediatePKIPathDone { return nil } mounts, err := v.client.Sys().ListMounts() if err != nil { return err } // Mount the backend if it isn't mounted already. if _, ok := mounts[v.config.IntermediatePKIPath]; !ok { err := v.client.Sys().Mount(v.config.IntermediatePKIPath, &vaultapi.MountInput{ Type: "pki", Description: "intermediate CA backend for Consul Connect", Config: vaultapi.MountConfigInput{ MaxLeaseTTL: "2160h", }, }) if err != nil { return err } } // Create the role for issuing leaf certs if it doesn't exist yet rolePath := v.config.IntermediatePKIPath + "roles/" + VaultCALeafCertRole role, err := v.client.Logical().Read(rolePath) if err != nil { return err } if role == nil { _, err := v.client.Logical().Write(rolePath, map[string]interface{}{ "allow_any_name": true, "allowed_uri_sans": "spiffe://*", "key_type": "any", "max_ttl": v.config.LeafCertTTL.String(), "no_store": true, "require_cn": false, }) if err != nil { return err } } v.setupIntermediatePKIPathDone = true return nil } func (v *VaultProvider) generateIntermediateCSR() (string, error) { err := v.setupIntermediatePKIPath() if err != nil { return "", err } // Generate a new intermediate CSR for the root to sign. uid, err := connect.CompactUID() if err != nil { return "", err } data, err := v.client.Logical().Write(v.config.IntermediatePKIPath+"intermediate/generate/internal", map[string]interface{}{ "common_name": connect.CACN("vault", uid, v.clusterID, v.isPrimary), "key_type": v.config.PrivateKeyType, "key_bits": v.config.PrivateKeyBits, "uri_sans": v.spiffeID.URI().String(), }) if err != nil { return "", err } if data == nil || data.Data["csr"] == "" { return "", fmt.Errorf("got empty value when generating intermediate CSR") } csr, ok := data.Data["csr"].(string) if !ok { return "", fmt.Errorf("csr result is not a string") } return csr, nil } // SetIntermediate writes the incoming intermediate and root certificates to the // intermediate backend (as a chain). func (v *VaultProvider) SetIntermediate(intermediatePEM, rootPEM string) error { if v.isPrimary { return fmt.Errorf("cannot set an intermediate using another root in the primary datacenter") } err := validateSetIntermediate( intermediatePEM, rootPEM, "", // we don't have access to the private key directly v.spiffeID, ) if err != nil { return err } _, err = v.client.Logical().Write(v.config.IntermediatePKIPath+"intermediate/set-signed", map[string]interface{}{ "certificate": fmt.Sprintf("%s\n%s", intermediatePEM, rootPEM), }) if err != nil { return err } return nil } // ActiveIntermediate returns the current intermediate certificate. func (v *VaultProvider) ActiveIntermediate() (string, error) { if err := v.setupIntermediatePKIPath(); err != nil { return "", err } cert, err := v.getCA(v.config.IntermediatePKIPath) // This error is expected when calling initializeSecondaryCA for the // first time. It means that the backend is mounted and ready, but // there is no intermediate. // This error is swallowed because there is nothing the caller can do // about it. The caller needs to handle the empty cert though and // create an intermediate CA. if err == ErrBackendNotInitialized { return "", nil } return cert, err } // getCA returns the raw CA cert for the given endpoint if there is one. // We have to use the raw NewRequest call here instead of Logical().Read // because the endpoint only returns the raw PEM contents of the CA cert // and not the typical format of the secrets endpoints. func (v *VaultProvider) getCA(path string) (string, error) { req := v.client.NewRequest("GET", "/v1/"+path+"/ca/pem") resp, err := v.client.RawRequest(req) if resp != nil { defer resp.Body.Close() } if resp != nil && resp.StatusCode == http.StatusNotFound { return "", ErrBackendNotMounted } if err != nil { return "", err } bytes, err := ioutil.ReadAll(resp.Body) if err != nil { return "", err } root := string(bytes) if root == "" { return "", ErrBackendNotInitialized } return root, nil } // GenerateIntermediate mounts the configured intermediate PKI backend if // necessary, then generates and signs a new CA CSR using the root PKI backend // and updates the intermediate backend to use that new certificate. func (v *VaultProvider) GenerateIntermediate() (string, error) { csr, err := v.generateIntermediateCSR() if err != nil { return "", err } // Sign the CSR with the root backend. intermediate, err := v.client.Logical().Write(v.config.RootPKIPath+"root/sign-intermediate", map[string]interface{}{ "csr": csr, "use_csr_values": true, "format": "pem_bundle", }) if err != nil { return "", err } if intermediate == nil || intermediate.Data["certificate"] == "" { return "", fmt.Errorf("got empty value when generating intermediate certificate") } // Set the intermediate backend to use the new certificate. _, err = v.client.Logical().Write(v.config.IntermediatePKIPath+"intermediate/set-signed", map[string]interface{}{ "certificate": intermediate.Data["certificate"], }) if err != nil { return "", err } return v.ActiveIntermediate() } // Sign calls the configured role in the intermediate PKI backend to issue // a new leaf certificate based on the provided CSR, with the issuing // intermediate CA cert attached. func (v *VaultProvider) Sign(csr *x509.CertificateRequest) (string, error) { var pemBuf bytes.Buffer if err := pem.Encode(&pemBuf, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csr.Raw}); err != nil { return "", err } // Use the leaf cert role to sign a new cert for this CSR. response, err := v.client.Logical().Write(v.config.IntermediatePKIPath+"sign/"+VaultCALeafCertRole, map[string]interface{}{ "csr": pemBuf.String(), "ttl": v.config.LeafCertTTL.String(), }) if err != nil { return "", fmt.Errorf("error issuing cert: %v", err) } if response == nil || response.Data["certificate"] == "" || response.Data["issuing_ca"] == "" { return "", fmt.Errorf("certificate info returned from Vault was blank") } cert, ok := response.Data["certificate"].(string) if !ok { return "", fmt.Errorf("certificate was not a string") } ca, ok := response.Data["issuing_ca"].(string) if !ok { return "", fmt.Errorf("issuing_ca was not a string") } return fmt.Sprintf("%s\n%s", cert, ca), nil } // SignIntermediate returns a signed CA certificate with a path length constraint // of 0 to ensure that the certificate cannot be used to generate further CA certs. func (v *VaultProvider) SignIntermediate(csr *x509.CertificateRequest) (string, error) { err := validateSignIntermediate(csr, v.spiffeID) if err != nil { return "", err } var pemBuf bytes.Buffer err = pem.Encode(&pemBuf, &pem.Block{Type: "CERTIFICATE REQUEST", Bytes: csr.Raw}) if err != nil { return "", err } // Sign the CSR with the root backend. data, err := v.client.Logical().Write(v.config.RootPKIPath+"root/sign-intermediate", map[string]interface{}{ "csr": pemBuf.String(), "use_csr_values": true, "format": "pem_bundle", "max_path_length": 0, }) if err != nil { return "", err } if data == nil || data.Data["certificate"] == "" { return "", fmt.Errorf("got empty value when generating intermediate certificate") } intermediate, ok := data.Data["certificate"].(string) if !ok { return "", fmt.Errorf("signed intermediate result is not a string") } return intermediate, nil } // CrossSignCA takes a CA certificate and cross-signs it to form a trust chain // back to our active root. func (v *VaultProvider) CrossSignCA(cert *x509.Certificate) (string, error) { var pemBuf bytes.Buffer err := pem.Encode(&pemBuf, &pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw}) if err != nil { return "", err } // Have the root PKI backend sign this cert. response, err := v.client.Logical().Write(v.config.RootPKIPath+"root/sign-self-issued", map[string]interface{}{ "certificate": pemBuf.String(), }) if err != nil { return "", fmt.Errorf("error having Vault cross-sign cert: %v", err) } if response == nil || response.Data["certificate"] == "" { return "", fmt.Errorf("certificate info returned from Vault was blank") } xcCert, ok := response.Data["certificate"].(string) if !ok { return "", fmt.Errorf("certificate was not a string") } return xcCert, nil } // SupportsCrossSigning implements Provider func (c *VaultProvider) SupportsCrossSigning() (bool, error) { return true, nil } // Cleanup unmounts the configured intermediate PKI backend. It's fine to tear // this down and recreate it on small config changes because the intermediate // certs get bundled with the leaf certs, so there's no cost to the CA changing. func (v *VaultProvider) Cleanup() error { return v.client.Sys().Unmount(v.config.IntermediatePKIPath) } func ParseVaultCAConfig(raw map[string]interface{}) (*structs.VaultCAProviderConfig, error) { config := structs.VaultCAProviderConfig{ CommonCAProviderConfig: defaultCommonConfig(), } decodeConf := &mapstructure.DecoderConfig{ DecodeHook: structs.ParseDurationFunc(), Result: &config, WeaklyTypedInput: true, } decoder, err := mapstructure.NewDecoder(decodeConf) if err != nil { return nil, err } if err := decoder.Decode(raw); err != nil { return nil, fmt.Errorf("error decoding config: %s", err) } if config.Token == "" { return nil, fmt.Errorf("must provide a Vault token") } if config.RootPKIPath == "" { return nil, fmt.Errorf("must provide a valid path to a root PKI backend") } if !strings.HasSuffix(config.RootPKIPath, "/") { config.RootPKIPath += "/" } if config.IntermediatePKIPath == "" { return nil, fmt.Errorf("must provide a valid path for the intermediate PKI backend") } if !strings.HasSuffix(config.IntermediatePKIPath, "/") { config.IntermediatePKIPath += "/" } if err := config.CommonCAProviderConfig.Validate(); err != nil { return nil, err } return &config, nil }