Allow management client to announce pss padding support

The --management-external-key option can currently indicate support
for 'nopadding' or 'pkcs1' signatures in the client. Add 'pss' as an
option to announce that PSS signing requests are accepted.

To match, extend the algorithm string in PK_SIGN request to
include the following format:

- RSA_PKCS1_PSS_PADDING,hashalg=name,saltlen=[max|digest]

Here 'name' is the short common name of the hash algorithm.
E.g., SHA1, SHA256 etc.

Existing formats 'ECDSA' and 'RSA_PKCS1_PADDING' are unchanged.

v2 changes: Fix typos and other sloppiness in documentation and
commit message.

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20211214165928.30676-10-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23430.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/doc/man-sections/management-options.rst b/doc/man-sections/management-options.rst
index 884750a65819ac2568f50e834a1dca317de1fd78..8dad52b38ec5b1b06b64bdda5cc8fa660eb5dbd0 100644 (file)
--- a/doc/man-sections/management-options.rst
+++ b/doc/man-sections/management-options.rst
@@ -85,9 +85,15 @@ server and client mode operations.
      management-external-key
      management-external-key nopadding
      management-external-key pkcs1
+     management-external-key pss
+
+  or any combination like:
+  ::
+
      management-external-key nopadding pkcs1
+     management-external-key pkcs1 pss
 
-  The optional parameters :code:`nopadding` and :code:`pkcs1` signal
+  The optional parameters :code:`nopadding` :code:`pkcs1` and :code:`pss` signal
   support for different padding algorithms. See
   :code:`doc/mangement-notes.txt` for a complete description of this
   feature.

diff --git a/doc/management-notes.txt b/doc/management-notes.txt
index 203d3d82276b61b546207d6873d2128b3cab47cc..7bb10c24c1c123e319c6fd91a8c27e235651282c 100644 (file)
--- a/doc/management-notes.txt
+++ b/doc/management-notes.txt
@@ -907,10 +907,24 @@ can be indicated in the signing request only if the client version is > 2"
 
 The currently defined padding algorithms are:
 
- - RSA_PKCS1_PADDING  -  PKCS1 padding and RSA signature
- - RSA_NO_PADDING     -  No padding may be added for the signature
- - ECDSA              -  EC signature.
-
+ - RSA_PKCS1_PADDING            -  PKCS1 padding and RSA signature
+ - RSA_NO_PADDING               -  No padding may be added for the signature
+ - ECDSA                        -  EC signature.
+ - RSA_PKCS1_PSS_PADDING,params -  RSA signature with PSS padding
+
+   The params for PSS are specified as 'hashalg=name,saltlen=[max|digest]'.
+
+   The hashalg names are short common names such as SHA256, SHA224, etc.
+   PSS saltlen="digest" means use the same size as the hash to sign, while
+   "max" indicates maximum possible saltlen which is
+   '(nbits-1)/8 - hlen - 2'. Here 'nbits' is the number of bits in the
+   key modulus and 'hlen' the size in octets of the hash.
+   (See: RFC 8017 sec 8.1.1 and 9.1.1)
+
+   In the case of PKCS1_PADDING, when the hash algorithm is not legacy
+   MD5-SHA1, the hash is encoded with DigestInfo header before presenting
+   to the management interface. This is identical to CKM_RSA_PKCS in Cryptoki
+   as well as what RSA_private_encrypt() in OpenSSL expects.
 
 COMMAND -- certificate (OpenVPN 2.4 or higher)
 ----------------------------------------------

diff --git a/src/openvpn/manage.h b/src/openvpn/manage.h
index 04dc98d14ac750034a6096699680988f0c23109a..5ed27c0c5430224d403dc1826f08fafb23098131 100644 (file)
--- a/src/openvpn/manage.h
+++ b/src/openvpn/manage.h
@@ -339,6 +339,7 @@ struct management *management_init(void);
 #define MF_QUERY_REMOTE             (1<<13)
 #define MF_QUERY_PROXY              (1<<14)
 #define MF_EXTERNAL_CERT            (1<<15)
+#define MF_EXTERNAL_KEY_PSSPAD      (1<<16)
 
 bool management_open(struct management *man,
                      const char *addr,

diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index aafec1a29397427627b99e0d975c4177eec8c8a3..42ea3baea82b8ed217bc6e00b9a12a8e69e1aef2 100644 (file)
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -60,6 +60,7 @@
 #include "forward.h"
 #include "ssl_verify.h"
 #include "platform.h"
+#include "xkey_common.h"
 #include <ctype.h>
 
 #include "memdbg.h"
@@ -2207,14 +2208,14 @@ options_postprocess_verify_ce(const struct options *options,
 
 #endif /* ifdef ENABLE_MANAGEMENT */
 
-#if  defined(ENABLE_MANAGEMENT)
+#if defined(ENABLE_MANAGEMENT) && !defined(HAVE_XKEY_PROVIDER)
     if ((tls_version_max() >= TLS_VER_1_3)
         && (options->management_flags & MF_EXTERNAL_KEY)
         && !(options->management_flags & (MF_EXTERNAL_KEY_NOPADDING))
         )
     {
-        msg(M_ERR, "management-external-key with OpenSSL 1.1.1 requires "
-            "the nopadding argument/support");
+        msg(M_FATAL, "management-external-key with TLS 1.3 or later requires "
+            "nopadding argument/support");
     }
 #endif
     /*
@@ -5520,6 +5521,10 @@ add_option(struct options *options,
             {
                 options->management_flags |= MF_EXTERNAL_KEY_PKCS1PAD;
             }
+            else if (streq(p[j], "pss"))
+            {
+                options->management_flags |= MF_EXTERNAL_KEY_PSSPAD;
+            }
             else
             {
                 msg(msglevel, "Unknown management-external-key flag: %s", p[j]);