blueprint: customizations for 'cacert'

pkg/blueprint/ca_customizations.go

@@ -0,0 +1,5 @@
+package blueprint
+
+type CACustomization struct {
+	PEMCerts []string `json:"pem_certs,omitempty" toml:"pem_certs,omitempty"`
+}

pkg/blueprint/customizations.go

@@ -6,6 +6,7 @@ import (
 	"slices"
 	"strings"
 
+	"github.com/osbuild/images/pkg/cert"
 	"github.com/osbuild/images/pkg/customizations/anaconda"
 )
 
@@ -32,6 +33,7 @@ type Customizations struct {
 	Installer          *InstallerCustomization        `json:"installer,omitempty" toml:"installer,omitempty"`
 	RPM                *RPMCustomization              `json:"rpm,omitempty" toml:"rpm,omitempty"`
 	RHSM               *RHSMCustomization             `json:"rhsm,omitempty" toml:"rhsm,omitempty"`
+	CACerts            *CACustomization               `json:"cacerts,omitempty" toml:"ca,omitempty"`
 }
 
 type IgnitionCustomization struct {
@@ -433,3 +435,32 @@ func (c *Customizations) GetRHSM() *RHSMCustomization {
 	}
 	return c.RHSM
 }
+
+func (c *Customizations) checkCACerts() error {
+	if c == nil {
+		return nil
+	}
+
+	if c.CACerts != nil {
+		for _, bundle := range c.CACerts.PEMCerts {
+			_, err := cert.ParseCerts(bundle)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+func (c *Customizations) GetCACerts() (*CACustomization, error) {
+	if c == nil {
+		return nil, nil
+	}
+
+	if err := c.checkCACerts(); err != nil {
+		return nil, err
+	}
+
+	return c.CACerts, nil
+}

pkg/cert/parsecerts.go

@@ -0,0 +1,46 @@
+package cert
+
+import (
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+	"fmt"
+)
+
+var ErrNoValidPEMCertificatesFound = errors.New("no valid PEM certificates found")
+
+// ParseCerts parses a PEM-encoded certificate chain formatted as concatenated strings
+// and returns a slice of x509.Certificate. In case of unparsable certificates, the
+// function returns an empty slice.
+// Returns an error when a cert cannot be parsed, or when no certificates are recognized
+// in the input.
+func ParseCerts(cert string) ([]*x509.Certificate, error) {
+	result := make([]*x509.Certificate, 0, 1)
+	block := []byte(cert)
+	var blocks [][]byte
+	for {
+		var certDERBlock *pem.Block
+		certDERBlock, block = pem.Decode(block)
+		if certDERBlock == nil {
+			break
+		}
+
+		if certDERBlock.Type == "CERTIFICATE" {
+			blocks = append(blocks, certDERBlock.Bytes)
+		}
+	}
+
+	for _, block := range blocks {
+		cert, err := x509.ParseCertificate(block)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse certificate: %w", err)
+		}
+		result = append(result, cert)
+	}
+
+	if len(result) == 0 {
+		return nil, fmt.Errorf("%w in: %s", ErrNoValidPEMCertificatesFound, cert)
+	}
+
+	return result, nil
+}

pkg/cert/parsecerts_test.go

@@ -0,0 +1,52 @@
+package cert
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// taken from osbuild:test/data/certs/cert1.pem
+const exampleCert = `
+-----BEGIN CERTIFICATE-----
+MIIDhTCCAm2gAwIBAgIUVya7VJ3O8W8SqwuEa0BZ4HSsXvAwDQYJKoZIhvcNAQEL
+BQAwUTELMAkGA1UEBhMCREUxDzANBgNVBAgMBkJlcmxpbjEPMA0GA1UEBwwGQmVy
+bGluMQwwCgYDVQQKDANPcmcxEjAQBgNVBAMMCWxvY2FsaG9zdDAgFw0yNDA4MjYx
+MDQyNDBaGA8yMTI0MDgwMjEwNDI0MFowUTELMAkGA1UEBhMCREUxDzANBgNVBAgM
+BkJlcmxpbjEPMA0GA1UEBwwGQmVybGluMQwwCgYDVQQKDANPcmcxEjAQBgNVBAMM
+CWxvY2FsaG9zdDCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAJnGjlvN
+O3F/Z7Lr/r+6Xp2DosnNwoPHhG2e61KnFzgZfaxbklal5ORpuV/gLIg7lrbpdZe7
+WvK+16RanL6fLitis/tYVFyvz1MXqBYYrEoFGvVg9fOiis7hjpdZcpNDH9SngoAN
+O0Wvv4T6LQS0cC7ZAFZjvmJ+RiZEbzRkNG5pUddZXbotE6htNfLgA5L1wIBgllrM
+4DVkG0yNKmzqPNzfPTbdUgWCfjaQShHy1GP8KNEwFxM31F2wvQxsEb77o1S44Out
+mlsi83tti6P7KjDk7w2j2zZO1X0xI8pflv3TBkJT1Am8vnk6rVnNO4pCpop3+kma
+pDUEzBQmSQA5R1ECAwEAAaNTMFEwHQYDVR0OBBYEFDxFcFgPEsgsDixfKxB0uYGN
+aJmzMB8GA1UdIwQYMBaAFDxFcFgPEsgsDixfKxB0uYGNaJmzMA8GA1UdEwEB/wQF
+MAMBAf8wDQYJKoZIhvcNAQELBQADggEBAFih4lUbLlhKwIAV9x3/W7Mih8xUEdZr
+olquZgaHedFet+ByAHvoES3pec7AVYTOD53mjgyZubD6INnVHzKyS4AG9ydD73o4
+cmm3DKxBaesvlHeTn0MOKsoM8QCxeyFJmiUPpgDBok/PFnbGR9+JcsrlGJAnsSKD
+vWpiwYcBauZ9nnK5yDe5M9XNFPkNDZzbKvWU7Sw3ziMT/+bRJse5vTrYcyOnNGgy
+gZNz2nimKy1U8XZVAVwOV0rdGEFrfMln8DkRW86rGK/EncaVsl0SSP/rmjQgiX8Q
+3CZraQGujJP932HSwUfdCX9yh+rTjE3MEnbqMoLzJa4BXB2aDQWtywU=
+-----END CERTIFICATE-----
+`
+
+func TestParseCerts(t *testing.T) {
+	certs, err := ParseCerts(exampleCert)
+	assert.Nil(t, err)
+	assert.Equal(t, len(certs), 1)
+	assert.Equal(t, "localhost", certs[0].Subject.CommonName)
+}
+
+func TestParseConcatenatedCerts(t *testing.T) {
+	certs, err := ParseCerts(exampleCert + "\n" + exampleCert)
+	assert.Nil(t, err)
+	assert.Equal(t, len(certs), 2)
+	assert.Equal(t, "localhost", certs[0].Subject.CommonName)
+}
+
+func TestParseGarbageCerts(t *testing.T) {
+	_, err := ParseCerts("garbage")
+	assert.NotNil(t, err)
+	assert.Equal(t, "no valid PEM certificates found in: garbage", err.Error())
+}

pkg/distro/fedora/images.go

@@ -226,6 +226,14 @@ func osCustomizations(
 	osc.Files = append(osc.Files, imageConfig.Files...)
 	osc.Directories = append(osc.Directories, imageConfig.Directories...)
 
+	ca, err := c.GetCACerts()
+	if err != nil {
+		panic(fmt.Sprintf("unexpected error checking CA certs: %v", err))
+	}
+	if ca != nil {
+		osc.CACerts = ca.PEMCerts
+	}
+
 	return osc, nil
 }
 

pkg/distro/rhel/images.go

@@ -271,6 +271,14 @@ func osCustomizations(
 		osc.NoBLS = *imageConfig.NoBLS
 	}
 
+	ca, err := c.GetCACerts()
+	if err != nil {
+		panic(fmt.Sprintf("unexpected error checking CA certs: %v", err))
+	}
+	if ca != nil {
+		osc.CACerts = ca.PEMCerts
+	}
+
 	return osc, nil
 }