secrets/database: adds ability to manage alternative credential types…

… and configuration (#15376)

builtin/logical/database/credentials.go

@@ -0,0 +1,169 @@
+package database
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/hashicorp/vault/helper/random"
+	"github.com/mitchellh/mapstructure"
+)
+
+// passwordGenerator generates password credentials.
+// A zero value passwordGenerator is usable.
+type passwordGenerator struct {
+	// PasswordPolicy is the named password policy used to generate passwords.
+	// If empty (default), a random string of 20 characters will be generated.
+	PasswordPolicy string `mapstructure:"password_policy,omitempty"`
+}
+
+// newPasswordGenerator returns a new passwordGenerator using the given config.
+// Default values will be set on the returned passwordGenerator if not provided
+// in the config.
+func newPasswordGenerator(config map[string]interface{}) (passwordGenerator, error) {
+	var pg passwordGenerator
+	if err := mapstructure.WeakDecode(config, &pg); err != nil {
+		return pg, err
+	}
+
+	return pg, nil
+}
+
+// Generate generates a password credential using the configured password policy.
+// Returns the generated password or an error.
+func (pg passwordGenerator) generate(ctx context.Context, b *databaseBackend, wrapper databaseVersionWrapper) (string, error) {
+	if !wrapper.isV5() && !wrapper.isV4() {
+		return "", fmt.Errorf("no underlying database specified")
+	}
+
+	// The database plugin generates the password if its interface is v4
+	if wrapper.isV4() {
+		password, err := wrapper.v4.GenerateCredentials(ctx)
+		if err != nil {
+			return "", err
+		}
+		return password, nil
+	}
+
+	if pg.PasswordPolicy == "" {
+		return random.DefaultStringGenerator.Generate(ctx, b.GetRandomReader())
+	}
+	return b.System().GeneratePasswordFromPolicy(ctx, pg.PasswordPolicy)
+}
+
+// configMap returns the configuration of the passwordGenerator
+// as a map from string to string.
+func (pg passwordGenerator) configMap() (map[string]interface{}, error) {
+	config := make(map[string]interface{})
+	if err := mapstructure.WeakDecode(pg, &config); err != nil {
+		return nil, err
+	}
+	return config, nil
+}
+
+// rsaKeyGenerator generates RSA key pair credentials.
+// A zero value rsaKeyGenerator is usable.
+type rsaKeyGenerator struct {
+	// Format is the output format of the generated private key.
+	// Options include: 'pkcs8' (default)
+	Format string `mapstructure:"format,omitempty"`
+
+	// KeyBits is the bit size of the RSA key to generate.
+	// Options include: 2048 (default), 3072, and 4096
+	KeyBits int `mapstructure:"key_bits,omitempty"`
+}
+
+// newRSAKeyGenerator returns a new rsaKeyGenerator using the given config.
+// Default values will be set on the returned rsaKeyGenerator if not provided
+// in the given config.
+func newRSAKeyGenerator(config map[string]interface{}) (rsaKeyGenerator, error) {
+	var kg rsaKeyGenerator
+	if err := mapstructure.WeakDecode(config, &kg); err != nil {
+		return kg, err
+	}
+
+	switch strings.ToLower(kg.Format) {
+	case "":
+		kg.Format = "pkcs8"
+	case "pkcs8":
+	default:
+		return kg, fmt.Errorf("invalid format: %v", kg.Format)
+	}
+
+	switch kg.KeyBits {
+	case 0:
+		kg.KeyBits = 2048
+	case 2048, 3072, 4096:
+	default:
+		return kg, fmt.Errorf("invalid key_bits: %v", kg.KeyBits)
+	}
+
+	return kg, nil
+}
+
+// Generate generates an RSA key pair. Returns a PEM-encoded, PKIX marshaled
+// public key and a PEM-encoded private key marshaled into the configuration
+// format (in that order) or an error.
+func (kg *rsaKeyGenerator) generate(r io.Reader) ([]byte, []byte, error) {
+	reader := rand.Reader
+	if r != nil {
+		reader = r
+	}
+
+	var keyBits int
+	switch kg.KeyBits {
+	case 0:
+		keyBits = 2048
+	case 2048, 3072, 4096:
+		keyBits = kg.KeyBits
+	default:
+		return nil, nil, fmt.Errorf("invalid key_bits: %v", kg.KeyBits)
+	}
+
+	key, err := rsa.GenerateKey(reader, keyBits)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	public, err := x509.MarshalPKIXPublicKey(key.Public())
+	if err != nil {
+		return nil, nil, err
+	}
+
+	var private []byte
+	switch strings.ToLower(kg.Format) {
+	case "", "pkcs8":
+		private, err = x509.MarshalPKCS8PrivateKey(key)
+		if err != nil {
+			return nil, nil, err
+		}
+	default:
+		return nil, nil, fmt.Errorf("invalid format: %v", kg.Format)
+	}
+
+	publicBlock := &pem.Block{
+		Type:  "PUBLIC KEY",
+		Bytes: public,
+	}
+	privateBlock := &pem.Block{
+		Type:  "PRIVATE KEY",
+		Bytes: private,
+	}
+
+	return pem.EncodeToMemory(publicBlock), pem.EncodeToMemory(privateBlock), nil
+}
+
+// configMap returns the configuration of the rsaKeyGenerator
+// as a map from string to string.
+func (kg rsaKeyGenerator) configMap() (map[string]interface{}, error) {
+	config := make(map[string]interface{})
+	if err := mapstructure.WeakDecode(kg, &config); err != nil {
+		return nil, err
+	}
+	return config, nil
+}