[Openvpn-devel] [S] Change in openvpn[master]: Zeroize tls-crypt-v2 client keys

[cron2 (C. Review) <ge...@op...>]

Attention is currently required from: flichtenheld, plaisthos.

cron2 has uploaded a new patch set (#2) to the change originally created by MaxF. ( http://gerrit.openvpn.net/c/openvpn/+/1315?usp=email )


Change subject: Zeroize tls-crypt-v2 client keys
......................................................................

Zeroize tls-crypt-v2 client keys

Joshua Rogers sent in a bug report generated with ZeroPath that the
tls-crypt-v2 client key is loaded before running the verify script. If
the verify script fails, the key is not zeroized.

While investigating this report, I found that free_tls_pre_decrypt_state
never zeroizes tls_wrap_tmp.original_wrap_keydata. So also when the
check is successful, key data will remain in memory when it is no longer
needed.

This commit moves the tls-crypt-v2-verify check before loading the key.
If it fails, original_wrap_keydata is zeroized. Also, in
free_tls_pre_decrypt_state, if a key has been loaded,
original_wrap_keydata is zeroized.

Reported-By: Joshua Rogers <co...@jo...>
Found-By: Zeropath

Change-Id: Icfcbf8ee20c1c0016eb98b570f24b9325b157c5c
Signed-off-by: Max Fillinger <ma...@ma...>
---
M src/openvpn/ssl_pkt.c
M src/openvpn/tls_crypt.c
2 files changed, 7 insertions(+), 5 deletions(-)


  git pull ssh://gerrit.openvpn.net:29418/openvpn refs/changes/15/1315/2

diff --git a/src/openvpn/ssl_pkt.c b/src/openvpn/ssl_pkt.c
index 825719c..d7f7ac3 100644
--- a/src/openvpn/ssl_pkt.c
+++ b/src/openvpn/ssl_pkt.c
@@ -280,6 +280,7 @@
     if (state->tls_wrap_tmp.cleanup_key_ctx)
     {
         free_key_ctx_bi(&state->tls_wrap_tmp.opt.key_ctx_bi);
+        secure_memzero(&state->tls_wrap_tmp.original_wrap_keydata, sizeof(state->tls_wrap_tmp.original_wrap_keydata));
     }
 }
 
diff --git a/src/openvpn/tls_crypt.c b/src/openvpn/tls_crypt.c
index 51b4eb3..a808de3 100644
--- a/src/openvpn/tls_crypt.c
+++ b/src/openvpn/tls_crypt.c
@@ -642,6 +642,12 @@
         return false;
     }
 
+    if (opt && opt->tls_crypt_v2_verify_script && !tls_crypt_v2_verify_metadata(ctx, opt))
+    {
+        secure_memzero(&ctx->original_wrap_keydata, sizeof(ctx->original_wrap_keydata));
+        return false;
+    }
+
     /* Load the decrypted key */
     ctx->mode = TLS_WRAP_CRYPT;
     ctx->cleanup_key_ctx = true;
@@ -652,11 +658,6 @@
     /* Remove client key from buffer so tls-crypt code can unwrap message */
     ASSERT(buf_inc_len(buf, -(BLEN(&wrapped_client_key))));
 
-    if (opt && opt->tls_crypt_v2_verify_script)
-    {
-        return tls_crypt_v2_verify_metadata(ctx, opt);
-    }
-
     return true;
 }
 

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Gerrit-MessageType: newpatchset
Gerrit-Project: openvpn
Gerrit-Branch: master
Gerrit-Change-Id: Icfcbf8ee20c1c0016eb98b570f24b9325b157c5c
Gerrit-Change-Number: 1315
Gerrit-PatchSet: 2
Gerrit-Owner: MaxF <ma...@ma...>
Gerrit-Reviewer: flichtenheld <fr...@li...>
Gerrit-Reviewer: plaisthos <arn...@rf...>
Gerrit-CC: openvpn-devel <ope...@li...>
Gerrit-Attention: plaisthos <arn...@rf...>
Gerrit-Attention: flichtenheld <fr...@li...>