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We'll validate user provided certificates, checking fields such as: * Common Name * Organization * NotBefore, NotAfter * DNS Subject Alternative Name Also, we ensure that the certificates are signed by the specified CAs.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,86 @@ | ||
| package pkiutil | ||
|
|
||
| import ( | ||
| "crypto/x509" | ||
| "fmt" | ||
| "slices" | ||
| "time" | ||
| ) | ||
|
|
||
| // CertCheck can be used to validate certificates. Unspecified fields are | ||
| // ignored. "NotBefore" and "NotAfter" are checked implicitly. | ||
| type CertCheck struct { | ||
| // Ensure that the certificate has the specified Common Name. | ||
| CN string | ||
| // Ensure that the certificate contains the following organizations. | ||
| O []string | ||
| // Ensure that the certificate contains the following DNS SANs. | ||
| DNSSANs []string | ||
| // Ensure that the certificate contains the following IP SANs. | ||
| IPSANs []string | ||
| // Validate the certificate against the specified CA certificate. | ||
| CaPEM string | ||
| AllowSelfSigned bool | ||
| } | ||
|
|
||
| func (check CertCheck) ValidateKeypair(certPEM string, keyPEM string) error { | ||
| cert, _, err := LoadCertificate(certPEM, keyPEM) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to parse certificate: %w", err) | ||
| } | ||
|
|
||
| return check.ValidateCert(cert) | ||
| } | ||
|
|
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| func (check CertCheck) ValidateCert(cert *x509.Certificate) error { | ||
| if check.CN != "" && check.CN != cert.Subject.CommonName { | ||
| return fmt.Errorf("invalid certificate CN, expected: %s, actual: %s ", | ||
| check.CN, cert.Subject.CommonName) | ||
| } | ||
| for _, checkO := range check.O { | ||
| if !slices.Contains(cert.Subject.Organization, checkO) { | ||
| return fmt.Errorf("missing cert organization: %s, actual: %v", | ||
| checkO, cert.Subject.Organization) | ||
| } | ||
| } | ||
|
|
||
| now := time.Now() | ||
| if now.Before(cert.NotBefore) { | ||
| return fmt.Errorf("invalid certificate, not valid before: %v, current time: %v", | ||
| cert.NotBefore, now) | ||
| } | ||
| if now.After(cert.NotAfter) { | ||
| return fmt.Errorf("certificate expired since: %v, current time: %v", | ||
| cert.NotAfter, now) | ||
| } | ||
|
|
||
| if !check.AllowSelfSigned { | ||
| verifyOpts := x509.VerifyOptions{} | ||
| if check.CaPEM != "" { | ||
| roots := x509.NewCertPool() | ||
| if !roots.AppendCertsFromPEM([]byte(check.CaPEM)) { | ||
| return fmt.Errorf("invalid CA certificate") | ||
| } | ||
| verifyOpts.Roots = roots | ||
| } | ||
|
|
||
| if _, err := cert.Verify(verifyOpts); err != nil { | ||
| return fmt.Errorf("certificate validation failure: %w", err) | ||
| } | ||
| } | ||
|
|
||
| for _, dnsName := range check.DNSSANs { | ||
| if err := cert.VerifyHostname(dnsName); err != nil { | ||
| return fmt.Errorf("certificate dns name (%s) validation failure: %w, allowed dns names: %v", | ||
| dnsName, err, cert.DNSNames) | ||
| } | ||
| } | ||
| for _, ip := range check.IPSANs { | ||
| if err := cert.VerifyHostname("[" + ip + "]"); err != nil { | ||
| return fmt.Errorf("certificate ip (%s) validation failure: %w, allowed IPs: %v", | ||
| ip, err, cert.IPAddresses) | ||
| } | ||
| } | ||
|
|
||
| return nil | ||
| } |