** Description changed:
[IMPACT]
openvpn when estabishing a tls connection will segfault when used with
Ubuntu's FIPS 140-2 libcrypto.so (openssl).
- openvpn tls connection does TLS PRF(pseudorandom function) to produce
securely generated pseudo random output that is used to generate keys.
- MD5 is used as the hash in this computation.
+ openvpn tls connection does TLS PRF(pseudorandom function) to produce
securely generated pseudo random output that is used to generate keys.
+ MD5 is used as the hash in this computation.
FIPS 140-2 does not permit MD5 use except when used for pseudorandom
function (PRF). When openvpn requests MD5 operation to FIPS-mode
libcrypto.so, since it is not allowed in general, FIPS-mode libcrypto.so
goes into an error state.
openvpn needs to set and pass a flag that FIPS-mode libcrypto.so
recognizes and that indicates it is using MD5 for PRF, thereby FIPS-mode
libcrypto.so will grant the request instead of entering an error state.
In non-FIPS libcrypto.so the flag has no meaning.
+ **NOTE: The openvpn 2.3 version in xenial has the above issue and an
+ additional one. It also use MD5 internally for configuration status
+ verification. It is not communicated externally. However, this
+ particular use of MD5 is not allowed by FIPS and thus when openvpn tries
+ to use FIPS-mode libcrypto.so to compute MD5, it results in openvpn
+ segfaulting. This 2nd issue was fixed by upstream openvpn community in
+ subsequent versions(2.4) to not use MD5 and use SHA(256) instead and
+ thus why bionic and disco do not require any change for this 2nd issue.
+
[TEST]
- Testing comprised establishing a tls connection between an openvpn client and
server. Once the connection was successfully established, a ping thru the
established vpn tunnel was done from the client for assurance.
-
- Because this flag has no meaning in non-FIPS libcrypto.so, nothing changes
for openvpn behaviour in disco. Interoperability testing was done to ensure no
regression. Test data reflects testing was done between openvpn server and
client with and without the patch and between various releases (xenial, bionic,
and disco).
+ Test data including commands and parameters are included below.
- Test Data will be attached below.
+ Testing comprised establishing a tls connection between an openvpn
+ client and server. Once the connection was successfully established, a
+ ping thru the established vpn tunnel was done from the client for
+ assurance.
- Note: a test was also done with a FIPS-enabled system to ensure
- everything worked and no regression.
+ Interoperability testing was done to ensure no regression. Test data
+ reflects testing was done between openvpn server and client with and
+ without the patch and between various releases (xenial, bionic, and
+ disco).
+
+ Test was also done with FIPS-enabled libcrypto.so to ensure everything
+ worked in FIPS mode.
+
+ [REGRESSION]
+ The FIPS-mode libcrypto.so flag passed by openvpn has no meaning in non-FIPS
libcrypto.so. Thus nothing changes for openvpn behaviour in non-FIPS mode in
regards to this.
+
+ xenial has additional change of using SHA instead of MD5 for
+ configuration status verification. This is an internal hash that is not
+ communicated externally. Thus it should not regress interoperability or
+ ability to establish connections.
** Changed in: openvpn (Ubuntu Disco)
Status: Incomplete => New
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https://bugs.launchpad.net/bugs/1807439
Title:
openvpn crashes when run with fips openssl
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