upstream: fix shield/unshield for xmss keys: - in ssh-agent we need

to delay the call to shield   until we have received key specific options. -
when serializing xmss keys for shield we need to deal with   all optional
components (e.g. state might not be loaded). ok djm@

OpenBSD-Commit-ID: cc2db82524b209468eb176d6b4d6b9486422f41f

1 files changed, 52 insertions, 4 deletions

diff --git a/sshkey-xmss.c b/sshkey-xmss.c
index e8e2e3816..88e9ddf4d 100644
--- a/sshkey-xmss.c
+++ b/sshkey-xmss.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey-xmss.c,v 1.7 2019/10/14 06:00:02 djm Exp $ */
+/* $OpenBSD: sshkey-xmss.c,v 1.8 2019/11/13 07:53:10 markus Exp $ */
 /*
  * Copyright (c) 2017 Markus Friedl.  All rights reserved.
  *
@@ -69,7 +69,7 @@ struct ssh_xmss_state {
         u_int32_t       maxidx;         /* restricted # of signatures */
         int             have_state;     /* .state file exists */
         int             lockfd;         /* locked in sshkey_xmss_get_state() */
-        int             allow_update;   /* allow sshkey_xmss_update_state() */
+        u_char          allow_update;   /* allow sshkey_xmss_update_state() */
         char            *enc_ciphername;/* encrypt state with cipher */
         u_char          *enc_keyiv;     /* encrypt state with key */
         u_int32_t       enc_keyiv_len;  /* length of enc_keyiv */
@@ -716,6 +716,7 @@ sshkey_xmss_serialize_state_opt(const struct sshkey *k, struct sshbuf *b,
 {
         struct ssh_xmss_state *state = k->xmss_state;
         int r = SSH_ERR_INVALID_ARGUMENT;
+        u_char have_stack, have_filename, have_enc;
 
         if (state == NULL)
                 return SSH_ERR_INVALID_ARGUMENT;
@@ -727,9 +728,35 @@ sshkey_xmss_serialize_state_opt(const struct sshkey *k, struct sshbuf *b,
                 break;
         case SSHKEY_SERIALIZE_FULL:
                 if ((r = sshkey_xmss_serialize_enc_key(k, b)) != 0)
-                        break;
+                        return r;
                 r = sshkey_xmss_serialize_state(k, b);
                 break;
+        case SSHKEY_SERIALIZE_SHIELD:
+                /* all of stack/filename/enc are optional */
+                have_stack = state->stack != NULL;
+                if ((r = sshbuf_put_u8(b, have_stack)) != 0)
+                        return r;
+                if (have_stack) {
+                        state->idx = PEEK_U32(k->xmss_sk);      /* update */
+                        if ((r = sshkey_xmss_serialize_state(k, b)) != 0)
+                                return r;
+                }
+                have_filename = k->xmss_filename != NULL;
+                if ((r = sshbuf_put_u8(b, have_filename)) != 0)
+                        return r;
+                if (have_filename &&
+                    (r = sshbuf_put_cstring(b, k->xmss_filename)) != 0)
+                        return r;
+                have_enc = state->enc_keyiv != NULL;
+                if ((r = sshbuf_put_u8(b, have_enc)) != 0)
+                        return r;
+                if (have_enc &&
+                    (r = sshkey_xmss_serialize_enc_key(k, b)) != 0)
+                        return r;
+                if ((r = sshbuf_put_u32(b, state->maxidx)) != 0 ||
+                    (r = sshbuf_put_u8(b, state->allow_update)) != 0)
+                        return r;
+                break;
         case SSHKEY_SERIALIZE_DEFAULT:
                 r = 0;
                 break;
@@ -808,8 +835,9 @@ sshkey_xmss_deserialize_state(struct sshkey *k, struct sshbuf *b)
 int
 sshkey_xmss_deserialize_state_opt(struct sshkey *k, struct sshbuf *b)
 {
+        struct ssh_xmss_state *state = k->xmss_state;
         enum sshkey_serialize_rep opts;
-        u_char have_state;
+        u_char have_state, have_stack, have_filename, have_enc;
         int r;
 
         if ((r = sshbuf_get_u8(b, &have_state)) != 0)
@@ -820,6 +848,26 @@ sshkey_xmss_deserialize_state_opt(struct sshkey *k, struct sshbuf *b)
         case SSHKEY_SERIALIZE_DEFAULT:
                 r = 0;
                 break;
+        case SSHKEY_SERIALIZE_SHIELD:
+                if ((r = sshbuf_get_u8(b, &have_stack)) != 0)
+                        return r;
+                if (have_stack &&
+                    (r = sshkey_xmss_deserialize_state(k, b)) != 0)
+                        return r;
+                if ((r = sshbuf_get_u8(b, &have_filename)) != 0)
+                        return r;
+                if (have_filename &&
+                    (r = sshbuf_get_cstring(b, &k->xmss_filename, NULL)) != 0)
+                        return r;
+                if ((r = sshbuf_get_u8(b, &have_enc)) != 0)
+                        return r;
+                if (have_enc &&
+                    (r = sshkey_xmss_deserialize_enc_key(k, b)) != 0)
+                        return r;
+                if ((r = sshbuf_get_u32(b, &state->maxidx)) != 0 ||
+                    (r = sshbuf_get_u8(b, &state->allow_update)) != 0)
+                        return r;
+                break;
         case SSHKEY_SERIALIZE_STATE:
                 if ((r = sshkey_xmss_deserialize_state(k, b)) != 0)
                         return r;