Refactored CRL checks

Signed-off-by: Adriaan de Jong <dejong@fox-it.com>
Acked-by: James Yonan <james@openvpn.net>
Signed-off-by: David Sommerseth <davids@redhat.com>

5 files changed, 100 insertions, 64 deletions

diff --git a/ssl.c b/ssl.c
index f171ed6..310e3cd 100644
--- a/ssl.c
+++ b/ssl.c
@@ -410,73 +410,12 @@ verify_cert(struct tls_session *session, x509_cert_t *cert, int cert_depth)
     {
       if (opt->ssl_flags & SSLF_CRL_VERIFY_DIR)
 	{
-	  char fn[256];
-	  int fd;
-	  char *serial = verify_get_serial(cert);
-	  if (!openvpn_snprintf(fn, sizeof(fn), "%s%c%s", opt->crl_file, OS_SPECIFIC_DIRSEP, serial))
-	    {
-	      msg (D_HANDSHAKE, "VERIFY CRL: filename overflow");
-	      verify_free_serial(serial);
-	      goto err;
-	    }
-	  fd = open (fn, O_RDONLY);
-	  if (fd >= 0)
-	    {
-	      msg (D_HANDSHAKE, "VERIFY CRL: certificate serial number %s is revoked", serial);
-	      verify_free_serial(serial);
-	      close(fd);
-	      goto err;
-	    }
-	  verify_free_serial(serial);
+	  if (verify_check_crl_dir(opt->crl_file, cert))
+	    goto err;
 	}
       else
 	{
-	  X509_CRL *crl=NULL;
-	  X509_REVOKED *revoked;
-	  BIO *in=NULL;
-	  int n,i,retval = 0;
-
-	  in=BIO_new(BIO_s_file());
-
-	  if (in == NULL) {
-	    msg (M_ERR, "CRL: BIO err");
-	    goto end;
-	  }
-	  if (BIO_read_filename(in, opt->crl_file) <= 0) {
-	    msg (M_ERR, "CRL: cannot read: %s", opt->crl_file);
-	    goto end;
-	  }
-	  crl=PEM_read_bio_X509_CRL(in,NULL,NULL,NULL);
-	  if (crl == NULL) {
-	    msg (M_ERR, "CRL: cannot read CRL from file %s", opt->crl_file);
-	    goto end;
-	  }
-
-	  if (X509_NAME_cmp(X509_CRL_get_issuer(crl), X509_get_issuer_name(cert)) != 0) {
-	    msg (M_WARN, "CRL: CRL %s is from a different issuer than the issuer of certificate %s", opt->crl_file, subject);
-	    retval = 1;
-	    goto end;
-	  }
-
-          n = sk_X509_REVOKED_num(X509_CRL_get_REVOKED(crl));
-
-          for (i = 0; i < n; i++) {
-            revoked = (X509_REVOKED *)sk_X509_REVOKED_value(X509_CRL_get_REVOKED(crl), i);
-            if (ASN1_INTEGER_cmp(revoked->serialNumber, X509_get_serialNumber(cert)) == 0) {
-              msg (D_HANDSHAKE, "CRL CHECK FAILED: %s is REVOKED",subject);
-              goto end;
-            }
-          }
-
-	  retval = 1;
-	  msg (D_HANDSHAKE, "CRL CHECK OK: %s",subject);
-
-	end:
-
-	  BIO_free(in);
-	  if (crl)
-	    X509_CRL_free (crl);
-	  if (!retval)
+	  if (verify_check_crl(opt->crl_file, cert, subject))
 	    goto err;
 	}
     }
diff --git a/ssl_verify.c b/ssl_verify.c
index d9acae9..2609c1d 100644
--- a/ssl_verify.c
+++ b/ssl_verify.c
@@ -532,6 +532,35 @@ verify_cert_call_command(const char *verify_command, struct env_set *es,
   return 1;		/* Reject connection */
 }
 
+/*
+ * check peer cert against CRL directory
+ */
+bool
+verify_check_crl_dir(const char *crl_dir, X509 *cert)
+{
+  char fn[256];
+  int fd;
+  char *serial = verify_get_serial(cert);
+
+  if (!openvpn_snprintf(fn, sizeof(fn), "%s%c%s", crl_dir, OS_SPECIFIC_DIRSEP, serial))
+    {
+      msg (D_HANDSHAKE, "VERIFY CRL: filename overflow");
+      verify_free_serial(serial);
+      return true;
+    }
+  fd = open (fn, O_RDONLY);
+  if (fd >= 0)
+    {
+      msg (D_HANDSHAKE, "VERIFY CRL: certificate serial number %s is revoked", serial);
+      verify_free_serial(serial);
+      close(fd);
+      return true;
+    }
+
+  verify_free_serial(serial);
+
+  return false;
+}
 
 /* ***************************************************************************
  * Functions for the management of deferred authentication when using
diff --git a/ssl_verify.h b/ssl_verify.h
index 5be2627..7e53513 100644
--- a/ssl_verify.h
+++ b/ssl_verify.h
@@ -253,6 +253,7 @@ int verify_cert_call_plugin(const struct plugin_list *plugins, struct env_set *e
     int cert_depth, x509_cert_t *cert, char *subject);
 int verify_cert_call_command(const char *verify_command, struct env_set *es,
     int cert_depth, x509_cert_t *cert, char *subject, const char *verify_export_cert);
+bool verify_check_crl_dir(const char *crl_dir, X509 *cert);
 
 #endif /* SSL_VERIFY_H_ */
 
diff --git a/ssl_verify_backend.h b/ssl_verify_backend.h
index a551beb..e6dfc59 100644
--- a/ssl_verify_backend.h
+++ b/ssl_verify_backend.h
@@ -192,4 +192,18 @@ bool verify_cert_eku (x509_cert_t *x509, const char * const expected_oid);
 const char *write_peer_cert(x509_cert_t *cert, const char *tmp_dir,
     struct gc_arena *gc);
 
+/*
+ * Check the certificate against a CRL file.
+ *
+ * @param crl_file	File name of the CRL file
+ * @param cert		Certificate to verify
+ * @param subject	Subject of the given certificate
+ *
+ * @return 		\c 1 if the CRL was not signed by the issuer of the
+ * 			certificate or does not contain an entry for it.
+ * 			\c 0 otherwise.
+ */
+bool verify_check_crl(const char *crl_file, x509_cert_t *cert,
+    const char *subject);
+
 #endif /* SSL_VERIFY_BACKEND_H_ */
diff --git a/ssl_verify_openssl.c b/ssl_verify_openssl.c
index cde100c..8bc49d7 100644
--- a/ssl_verify_openssl.c
+++ b/ssl_verify_openssl.c
@@ -521,3 +521,56 @@ write_peer_cert(X509 *peercert, const char *tmp_dir, struct gc_arena *gc)
 
 #endif /* OPENSSL_VERSION_NUMBER */
 
+/*
+ * check peer cert against CRL
+ */
+bool
+verify_check_crl(const char *crl_file, X509 *peer_cert, const char *subject)
+{
+  X509_CRL *crl=NULL;
+  X509_REVOKED *revoked;
+  BIO *in=NULL;
+  int n,i,retval = 0;
+
+  in=BIO_new(BIO_s_file());
+
+  if (in == NULL) {
+    msg (M_ERR, "CRL: BIO err");
+    goto end;
+  }
+  if (BIO_read_filename(in, crl_file) <= 0) {
+    msg (M_ERR, "CRL: cannot read: %s", crl_file);
+    goto end;
+  }
+  crl=PEM_read_bio_X509_CRL(in,NULL,NULL,NULL);
+  if (crl == NULL) {
+    msg (M_ERR, "CRL: cannot read CRL from file %s", crl_file);
+    goto end;
+  }
+
+  if (X509_NAME_cmp(X509_CRL_get_issuer(crl), X509_get_issuer_name(peer_cert)) != 0) {
+    msg (M_WARN, "CRL: CRL %s is from a different issuer than the issuer of "
+	"certificate %s", crl_file, subject);
+    retval = 1;
+    goto end;
+  }
+
+  n = sk_X509_REVOKED_num(X509_CRL_get_REVOKED(crl));
+  for (i = 0; i < n; i++) {
+    revoked = (X509_REVOKED *)sk_X509_REVOKED_value(X509_CRL_get_REVOKED(crl), i);
+    if (ASN1_INTEGER_cmp(revoked->serialNumber, X509_get_serialNumber(peer_cert)) == 0) {
+      msg (D_HANDSHAKE, "CRL CHECK FAILED: %s is REVOKED",subject);
+      goto end;
+    }
+  }
+
+  retval = 1;
+  msg (D_HANDSHAKE, "CRL CHECK OK: %s",subject);
+
+end:
+  BIO_free(in);
+  if (crl)
+    X509_CRL_free (crl);
+
+  return !retval;
+}