upstream: Add experimental support for PQC XMSS keys (Extended

Hash-Based Signatures) The code is not compiled in by default (see WITH_XMSS
in Makefile.inc) Joint work with stefan-lukas_gazdag at genua.eu See
https://tools.ietf.org/html/draft-irtf-cfrg-xmss-hash-based-signatures-12 ok
djm@

OpenBSD-Commit-ID: ef3eccb96762a5d6f135d7daeef608df7776a7ac

1 files changed, 18 insertions, 21 deletions

diff --git a/authfd.c b/authfd.c
index 148bc9bfb..1eff7ba94 100644
--- a/authfd.c
+++ b/authfd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: authfd.c,v 1.107 2018/02/10 09:25:34 djm Exp $ */
+/* $OpenBSD: authfd.c,v 1.108 2018/02/23 15:58:37 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -129,7 +129,7 @@ ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply)
 
         /* Get the length of the message, and format it in the buffer. */
         len = sshbuf_len(request);
-        put_u32(buf, len);
+        POKE_U32(buf, len);
 
         /* Send the length and then the packet to the agent. */
         if (atomicio(vwrite, sock, buf, 4) != 4 ||
@@ -144,7 +144,7 @@ ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply)
             return SSH_ERR_AGENT_COMMUNICATION;
 
         /* Extract the length, and check it for sanity. */
-        len = get_u32(buf);
+        len = PEEK_U32(buf);
         if (len > MAX_AGENT_REPLY_LEN)
                 return SSH_ERR_INVALID_FORMAT;
 
@@ -391,19 +391,7 @@ ssh_agent_sign(int sock, const struct sshkey *key,
 
 
 static int
-ssh_encode_identity_ssh2(struct sshbuf *b, const struct sshkey *key,
-    const char *comment)
-{
-        int r;
-
-        if ((r = sshkey_private_serialize(key, b)) != 0 ||
-            (r = sshbuf_put_cstring(b, comment)) != 0)
-                return r;
-        return 0;
-}
-
-static int
-encode_constraints(struct sshbuf *m, u_int life, u_int confirm)
+encode_constraints(struct sshbuf *m, u_int life, u_int confirm, u_int maxsign)
 {
         int r;
 
@@ -416,6 +404,11 @@ encode_constraints(struct sshbuf *m, u_int life, u_int confirm)
                 if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_CONFIRM)) != 0)
                         goto out;
         }
+        if (maxsign != 0) {
+                if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_MAXSIGN)) != 0 ||
+                    (r = sshbuf_put_u32(m, maxsign)) != 0)
+                        goto out;
+        }
         r = 0;
  out:
         return r;
@@ -427,10 +420,10 @@ encode_constraints(struct sshbuf *m, u_int life, u_int confirm)
  */
 int
 ssh_add_identity_constrained(int sock, const struct sshkey *key,
-    const char *comment, u_int life, u_int confirm)
+    const char *comment, u_int life, u_int confirm, u_int maxsign)
 {
         struct sshbuf *msg;
-        int r, constrained = (life || confirm);
+        int r, constrained = (life || confirm || maxsign);
         u_char type;
 
         if ((msg = sshbuf_new()) == NULL)
@@ -447,11 +440,15 @@ ssh_add_identity_constrained(int sock, const struct sshkey *key,
 #endif
         case KEY_ED25519:
         case KEY_ED25519_CERT:
+        case KEY_XMSS:
+        case KEY_XMSS_CERT:
                 type = constrained ?
                     SSH2_AGENTC_ADD_ID_CONSTRAINED :
                     SSH2_AGENTC_ADD_IDENTITY;
                 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
-                    (r = ssh_encode_identity_ssh2(msg, key, comment)) != 0)
+                    (r = sshkey_private_serialize_maxsign(key, msg, maxsign,
+                    NULL)) != 0 ||
+                    (r = sshbuf_put_cstring(msg, comment)) != 0)
                         goto out;
                 break;
         default:
@@ -459,7 +456,7 @@ ssh_add_identity_constrained(int sock, const struct sshkey *key,
                 goto out;
         }
         if (constrained &&
-            (r = encode_constraints(msg, life, confirm)) != 0)
+            (r = encode_constraints(msg, life, confirm, maxsign)) != 0)
                 goto out;
         if ((r = ssh_request_reply(sock, msg, msg)) != 0)
                 goto out;
@@ -537,7 +534,7 @@ ssh_update_card(int sock, int add, const char *reader_id, const char *pin,
             (r = sshbuf_put_cstring(msg, pin)) != 0)
                 goto out;
         if (constrained &&
-            (r = encode_constraints(msg, life, confirm)) != 0)
+            (r = encode_constraints(msg, life, confirm, 0)) != 0)
                 goto out;
         if ((r = ssh_request_reply(sock, msg, msg)) != 0)
                 goto out;