Fix segfault when using crypto lib without AES-256-CTR or SHA256

Openvpn segfaults on RHEL5/CentOS5 when using --tls-crypt, because it
doesn't have AES-256-CTR support:

openvpn[15330]: OpenVPN 2.4.0 x86_64-redhat-linux-gnu [SSL (OpenSSL)]
[LZO] [LZ4] [EPOLL] [MH/PKTINFO] built on Jan 17 2017
openvpn[15330]: library versions: OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008,
LZO 2.09, LZ4 1.7.5
openvpn[15331]: NOTE: the current --script-security setting may allow this
configuration to call user-defined scripts
kernel: openvpn[15331]: segfault at 0000000000000008 rip 000000000040ebe0
rsp 00007fffdcfc5738 error 4

This patch fixes it so it shows:

openvpn[424]: ERROR: --tls-crypt requires AES-256-CTR support.
openvpn[424]: Exiting due to fatal error

Trac: #825
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <345db0ac-f6e8-8490-a80a-ffbd81972c07@karger.me>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14138.html

Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/tls_crypt.c b/src/openvpn/tls_crypt.c
index 804c27926aef6454bc08384a12ca519004033ee5..e2fdbed2f4289ca8fdd4b6afc99a309ff823ad23 100644 (file)
--- a/src/openvpn/tls_crypt.c
+++ b/src/openvpn/tls_crypt.c
@@ -51,9 +51,7 @@ tls_crypt_init_key(struct key_ctx_bi *key, const char *key_file,
 
     struct key_type kt;
     kt.cipher = cipher_kt_get("AES-256-CTR");
-    kt.cipher_length = cipher_kt_key_size(kt.cipher);
     kt.digest = md_kt_get("SHA256");
-    kt.hmac_length = md_kt_size(kt.digest);
 
     if (!kt.cipher)
     {
@@ -64,6 +62,9 @@ tls_crypt_init_key(struct key_ctx_bi *key, const char *key_file,
         msg(M_FATAL, "ERROR: --tls-crypt requires HMAC-SHA-256 support.");
     }
 
+    kt.cipher_length = cipher_kt_key_size(kt.cipher);
+    kt.hmac_length = md_kt_size(kt.digest);
+
     crypto_read_openvpn_key(&kt, key, key_file, key_inline, key_direction,
                             "Control Channel Encryption", "tls-crypt");
 }