[crypto] Automatically perform OCSP checks when applicable

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/net/validator.c

 #include <ipxe/dhcp.h>
 #include <ipxe/base64.h>
 #include <ipxe/crc32.h>
+#include <ipxe/ocsp.h>
 #include <ipxe/validator.h>
 
 /** @file
 	struct interface job;
 	/** Data transfer interface */
 	struct interface xfer;
+
 	/** Process */
 	struct process process;
+
 	/** X.509 certificate chain */
 	struct x509_chain *chain;
+	/** OCSP check */
+	struct ocsp_check *ocsp;
 	/** Data buffer */
 	struct xfer_buffer buffer;
+	/** Action to take upon completed transfer */
+	int ( * done ) ( struct validator *validator, const void *data,
+			 size_t len );
 };
 
 /**
 
 	DBGC2 ( validator, "VALIDATOR %p freed\n", validator );
 	x509_chain_put ( validator->chain );
+	ocsp_put ( validator->ocsp );
 	xferbuf_done ( &validator->buffer );
 	free ( validator );
 }
 /** Default cross-signed certificate source */
 static const char crosscert_default[] = "http://ca.ipxe.org/auto";
 
+/**
+ * Append cross-signing certificates to certificate chain
+ *
+ * @v validator		Certificate validator
+ * @v data		Raw cross-signing certificate data
+ * @v len		Length of raw data
+ * @ret rc		Return status code
+ */
+static int validator_append ( struct validator *validator,
+			      const void *data, size_t len ) {
+	struct asn1_cursor cursor;
+	struct x509_chain *certs;
+	struct x509_certificate *cert;
+	struct x509_certificate *last;
+	int rc;
+
+	/* Allocate certificate list */
+	certs = x509_alloc_chain();
+	if ( ! certs ) {
+		rc = -ENOMEM;
+		goto err_alloc_certs;
+	}
+
+	/* Initialise cursor */
+	cursor.data = data;
+	cursor.len = len;
+
+	/* Enter certificateSet */
+	if ( ( rc = asn1_enter ( &cursor, ASN1_SET ) ) != 0 ) {
+		DBGC ( validator, "VALIDATOR %p could not enter "
+		       "certificateSet: %s\n", validator, strerror ( rc ) );
+		goto err_certificateset;
+	}
+
+	/* Add each certificate to list */
+	while ( cursor.len ) {
+
+		/* Add certificate to chain */
+		if ( ( rc = x509_append_raw ( certs, cursor.data,
+					      cursor.len ) ) != 0 ) {
+			DBGC ( validator, "VALIDATOR %p could not append "
+			       "certificate: %s\n",
+			       validator, strerror ( rc) );
+			DBGC_HDA ( validator, 0, cursor.data, cursor.len );
+			return rc;
+		}
+		cert = x509_last ( certs );
+		DBGC ( validator, "VALIDATOR %p found certificate %s\n",
+		       validator, cert->subject.name );
+
+		/* Move to next certificate */
+		asn1_skip_any ( &cursor );
+	}
+
+	/* Append certificates to chain */
+	last = x509_last ( validator->chain );
+	if ( ( rc = x509_auto_append ( validator->chain, certs ) ) != 0 ) {
+		DBGC ( validator, "VALIDATOR %p could not append "
+		       "certificates: %s\n", validator, strerror ( rc ) );
+		goto err_auto_append;
+	}
+
+	/* Check that at least one certificate has been added */
+	if ( last == x509_last ( validator->chain ) ) {
+		DBGC ( validator, "VALIDATOR %p failed to append any "
+		       "applicable certificates\n", validator );
+		rc = -EACCES;
+		goto err_no_progress;
+	}
+
+	/* Drop reference to certificate list */
+	x509_chain_put ( certs );
+
+	return 0;
+
+ err_no_progress:
+ err_auto_append:
+ err_certificateset:
+	x509_chain_put ( certs );
+ err_alloc_certs:
+	return rc;
+}
+
 /**
  * Start download of cross-signing certificate
  *
 	DBGC ( validator, "VALIDATOR %p downloading cross-signed certificate "
 	       "from %s\n", validator, uri_string );
 
+	/* Set completion handler */
+	validator->done = validator_append;
+
 	/* Open URI */
 	if ( ( rc = xfer_open_uri_string ( &validator->xfer,
 					   uri_string ) ) != 0 ) {
 	return rc;
 }
 
+/****************************************************************************
+ *
+ * OCSP checks
+ *
+ */
+
 /**
- * Append cross-signing certificates to certificate chain
+ * Validate OCSP response
  *
  * @v validator		Certificate validator
- * @v data		Raw cross-signing certificate data
+ * @v data		Raw OCSP response
  * @v len		Length of raw data
  * @ret rc		Return status code
  */
-static int validator_append ( struct validator *validator,
-			      const void *data, size_t len ) {
-	struct asn1_cursor cursor;
-	struct x509_chain *certs;
-	struct x509_certificate *cert;
-	struct x509_certificate *last;
+static int validator_ocsp_validate ( struct validator *validator,
+				     const void *data, size_t len ) {
+	time_t now;
 	int rc;
 
-	/* Allocate certificate list */
-	certs = x509_alloc_chain();
-	if ( ! certs ) {
-		rc = -ENOMEM;
-		goto err_alloc_certs;
+	/* Record OCSP response */
+	if ( ( rc = ocsp_response ( validator->ocsp, data, len ) ) != 0 ) {
+		DBGC ( validator, "VALIDATOR %p could not record OCSP "
+		       "response: %s\n", validator, strerror ( rc ) );
+		return rc;
 	}
 
-	/* Initialise cursor */
-	cursor.data = data;
-	cursor.len = len;
-
-	/* Enter certificateSet */
-	if ( ( rc = asn1_enter ( &cursor, ASN1_SET ) ) != 0 ) {
-		DBGC ( validator, "VALIDATOR %p could not enter "
-		       "certificateSet: %s\n", validator, strerror ( rc ) );
-		goto err_certificateset;
+	/* Validate OCSP response */
+	now = time ( NULL );
+	if ( ( rc = ocsp_validate ( validator->ocsp, now ) ) != 0 ) {
+		DBGC ( validator, "VALIDATOR %p could not validate OCSP "
+		       "response: %s\n", validator, strerror ( rc ) );
+		return rc;
 	}
 
-	/* Add each certificate to list */
-	while ( cursor.len ) {
+	/* Drop reference to OCSP check */
+	ocsp_put ( validator->ocsp );
+	validator->ocsp = NULL;
 
-		/* Add certificate to chain */
-		if ( ( rc = x509_append_raw ( certs, cursor.data,
-					      cursor.len ) ) != 0 ) {
-			DBGC ( validator, "VALIDATOR %p could not append "
-			       "certificate: %s\n",
-			       validator, strerror ( rc) );
-			DBGC_HDA ( validator, 0, cursor.data, cursor.len );
-			return rc;
-		}
-		cert = x509_last ( certs );
-		DBGC ( validator, "VALIDATOR %p found certificate %s\n",
-		       validator, cert->subject.name );
+	return 0;
+}
 
-		/* Move to next certificate */
-		asn1_skip_any ( &cursor );
-	}
+/**
+ * Start OCSP check
+ *
+ * @v validator		Certificate validator
+ * @v cert		Certificate to check
+ * @v issuer		Issuing certificate
+ * @ret rc		Return status code
+ */
+static int validator_start_ocsp ( struct validator *validator,
+				  struct x509_certificate *cert,
+				  struct x509_certificate *issuer ) {
+	const char *uri_string;
+	int rc;
 
-	/* Append certificates to chain */
-	last = x509_last ( validator->chain );
-	if ( ( rc = x509_auto_append ( validator->chain, certs ) ) != 0 ) {
-		DBGC ( validator, "VALIDATOR %p could not append "
-		       "certificates: %s\n", validator, strerror ( rc ) );
-		goto err_auto_append;
+	/* Create OCSP check */
+	assert ( validator->ocsp == NULL );
+	if ( ( rc = ocsp_check ( cert, issuer, &validator->ocsp ) ) != 0 ) {
+		DBGC ( validator, "VALIDATOR %p could not create OCSP check: "
+		       "%s\n", validator, strerror ( rc ) );
+		return rc;
 	}
 
-	/* Check that at least one certificate has been added */
-	if ( last == x509_last ( validator->chain ) ) {
-		DBGC ( validator, "VALIDATOR %p failed to append any "
-		       "applicable certificates\n", validator );
-		rc = -EACCES;
-		goto err_no_progress;
-	}
+	/* Set completion handler */
+	validator->done = validator_ocsp_validate;
 
-	/* Drop reference to certificate list */
-	x509_chain_put ( certs );
+	/* Open URI */
+	uri_string = validator->ocsp->uri_string;
+	DBGC ( validator, "VALIDATOR %p performing OCSP check at %s\n",
+	       validator, uri_string );
+	if ( ( rc = xfer_open_uri_string ( &validator->xfer,
+					   uri_string ) ) != 0 ) {
+		DBGC ( validator, "VALIDATOR %p could not open %s: %s\n",
+		       validator, uri_string, strerror ( rc ) );
+		return rc;
+	}
 
 	return 0;
-
- err_no_progress:
- err_auto_append:
- err_certificateset:
-	x509_chain_put ( certs );
- err_alloc_certs:
-	return rc;
 }
 
 /****************************************************************************
 
 	/* Check for errors */
 	if ( rc != 0 ) {
-		DBGC ( validator, "VALIDATOR %p download failed: %s\n",
+		DBGC ( validator, "VALIDATOR %p transfer failed: %s\n",
 		       validator, strerror ( rc ) );
-		goto err_download;
+		goto err_transfer;
 	}
-	DBGC2 ( validator, "VALIDATOR %p download complete\n", validator );
+	DBGC2 ( validator, "VALIDATOR %p transfer complete\n", validator );
 
-	/* Append downloaded certificates */
-	if ( ( rc = validator_append ( validator, validator->buffer.data,
+	/* Process completed download */
+	assert ( validator->done != NULL );
+	if ( ( rc = validator->done ( validator, validator->buffer.data,
 				       validator->buffer.len ) ) != 0 )
 		goto err_append;
 
 	return;
 
  err_append:
- err_download:
+ err_transfer:
 	validator_finished ( validator, rc );
 }
 
  * @v validator		Certificate validator
  */
 static void validator_step ( struct validator *validator ) {
-	struct x509_certificate *last = x509_last ( validator->chain );
+	struct x509_link *link;
+	struct x509_link *previous;
+	struct x509_certificate *cert;
+	struct x509_certificate *issuer = NULL;
+	struct x509_certificate *last;
 	time_t now;
 	int rc;
 
 		return;
 	}
 
+	/* If there is a certificate that could be validated using
+	 * OCSP, try it.
+	 */
+	list_for_each_entry ( link, &validator->chain->links, list ) {
+		cert = issuer;
+		issuer = link->cert;
+		previous = link;
+		if ( ! cert )
+			continue;
+		if ( ! issuer->valid )
+			continue;
+		/* The issuer is valid, but this certificate is not
+		 * yet valid.  If OCSP is applicable, start it.
+		 */
+		if ( cert->extensions.auth_info.ocsp.uri &&
+		     ( ! cert->extensions.auth_info.ocsp.good ) ) {
+			/* Start OCSP */
+			if ( ( rc = validator_start_ocsp ( validator, cert,
+							   issuer ) ) != 0 ) {
+				validator_finished ( validator, rc );
+				return;
+			}
+			return;
+		}
+		/* Otherwise, this is a permanent failure */
+		validator_finished ( validator, rc );
+		return;
+	}
+
 	/* If chain ends with a self-issued certificate, then there is
 	 * nothing more to do.
 	 */
+	last = x509_last ( validator->chain );
 	if ( asn1_compare ( &last->issuer.raw, &last->subject.raw ) == 0 ) {
 		validator_finished ( validator, rc );
 		return;