Re: [Openvpn-devel] [PATCH 1/2] Detect unusable ciphers on patched OpenSSL of RHEL/Centos

[David Sommerseth]

On 18/08/2021 23:33, Arne Schwabe wrote:

OpenSSL on RHEL 8 and CentOS 8 system when these system are put into
FIPS mode need extra code to figure out if a specific cipher algorithm
is usable on these system. This is particularly problem in data-ciphers
as the errors might occur much later when a client connects and as these
cipher are not caught during config initialisation.

This also prepares for adding Chacha20-Poly1305 when available to
data-ciphers by making the detection logic used to check if
cipher_kt_get returns non-NULL work on these systems.

Signed-off-by: Arne Schwabe 
---
  src/openvpn/crypto.c |  6 ++
  src/openvpn/crypto_openssl.c | 10 ++
  2 files changed, 16 insertions(+)



I've Looked at the code, built it on a RHEL-8.4 box with FIPS enabled 
and tested the binary with FIPS both enabled and disabled.  It works 
smoothly there.


The OPENSSL_FIPS macro is defined in 
/usr/include/openssl/opensslconf-x86_64.h. So is handled outside of 
OpenVPN, and without that macro we don't need to be concerned about the 
FIPS_mode() function.


As mentioned in the community developer meeting today, there are some 
concerns about the recently released OpenSSL 3.0 and FIPS - but lets 
tackle that further down the road once we have distributions with the 
latest OpenSSL library more easily available.


The bottom line is ...

Acked-By: David Sommerseth 


--
kind regards,

David Sommerseth
OpenVPN Inc




OpenPGP_signature
Description: OpenPGP digital signature
___
Openvpn-devel mailing list
Openvpn-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/openvpn-devel

[Openvpn-devel] [PATCH 1/2] Detect unusable ciphers on patched OpenSSL of RHEL/Centos

[Arne Schwabe]

OpenSSL on RHEL 8 and CentOS 8 system when these system are put into
FIPS mode need extra code to figure out if a specific cipher algorithm
is usable on these system. This is particularly problem in data-ciphers
as the errors might occur much later when a client connects and as these
cipher are not caught during config initialisation.

This also prepares for adding Chacha20-Poly1305 when available to
data-ciphers by making the detection logic used to check if
cipher_kt_get returns non-NULL work on these systems.

Signed-off-by: Arne Schwabe 
---
 src/openvpn/crypto.c |  6 ++
 src/openvpn/crypto_openssl.c | 10 ++
 2 files changed, 16 insertions(+)

diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c
index b9c95225a..1dfc760f9 100644
--- a/src/openvpn/crypto.c
+++ b/src/openvpn/crypto.c
@@ -1806,6 +1806,12 @@ print_cipher(const cipher_kt_t *cipher)
 {
 printf(", TLS client/server mode only");
 }
+#ifdef OPENSSL_FIPS
+if (FIPS_mode() && !(EVP_CIPHER_flags(cipher) & EVP_CIPH_FLAG_FIPS))
+{
+printf(", disabled by FIPS mode");
+}
+#endif
 
 printf(")\n");
 }
diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
index b55d32b2c..419265a51 100644
--- a/src/openvpn/crypto_openssl.c
+++ b/src/openvpn/crypto_openssl.c
@@ -599,7 +599,17 @@ cipher_kt_get(const char *ciphername)
 return NULL;
 }
 
+#ifdef OPENSSL_FIPS
+/* Rhel 8/CentOS 8 have a patched OpenSSL version that return a cipher
+ * here that is actually not usable if in FIPS mode */
 
+if (FIPS_mode() && !(EVP_CIPHER_flags(cipher) & EVP_CIPH_FLAG_FIPS))
+{
+msg(D_LOW, "Cipher algorithm '%s' is known by OpenSSL library but "
+"currently disabled by running in FIPS mode.", ciphername);
+return NULL;
+}
+#endif
 if (EVP_CIPHER_key_length(cipher) > MAX_CIPHER_KEY_LENGTH)
 {
 msg(D_LOW, "Cipher algorithm '%s' uses a default key size (%d bytes) "
-- 
2.32.0



___
Openvpn-devel mailing list
Openvpn-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/openvpn-devel