This bug has been reported: 1.Upstream Bug: https://community.openvpn.net/openvpn/ticket/725 2.Suse Bug report: https://build.opensuse.org/package/view_file/network:vpn/openvpn/openvpn-fips140-2.3.2.patch
** Description changed: [IMPACT] + openvpn segfaults when using fips-mode openssl because of MD5. + + xenial has version 2.3.x and subsequent releases have 2.4.x. + MD5 is used in 2 places in 2.3.x and one place in 2.4.x. + + First place: 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. 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. + The context flag value, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, is defined in + both FIPS and non-FIPS libcrypto.so. However, the MD5 check for it is + only in FIPS-mode libcrypto.so to permit MD5. In non-FIPS libcrypto.so + this check does not exist since it always permits MD5. openvpn should + use this flag when it makes its MD5 request. - **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. + Second place (only in 2.3.x): + **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, cosmic, and disco do not require any change for this 2nd issue. [TEST] Test data including commands and parameters are included 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. 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. + The context flag value, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, is defined in both FIPS-mode openssl and non-FIPS openssl. However, the MD5-permit check against this flag-value does not occur in non-FIPS libcrypto.so, so there should be no change in behaviour. non-FIPS libcrypto.so should continue to service all MD5 requests. - 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. + xenial with version 2.3.x, 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. ** Bug watch added: community.openvpn.net/openvpn/ #725 https://community.openvpn.net/openvpn/ticket/725 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1807439 Title: openvpn crashes when run with fips openssl To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openvpn/+bug/1807439/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
