This avoids the use of a variable length array, which should probably
be avoided in general due to potential performance, portability and
security issues (not in this particular case, though).
Closesstrongswan/strongswan#1095
GCC assumes this->b is zero (or may be zero) and spits out the following
warning (or error with -Werror):
src/libstrongswan/plugins/fips_prf/fips_prf.c:124:12: error: array subscript 18446744073709551615 is above array bounds of ‘uint8_t[<U8090>]’ {aka ‘unsigned char[<U8090>]’} [-Werror=array-bounds]
124 | one[this->b - 1] = 0x01;
| ~~~^~~~~~~~~~~~~
More of this code was already removed with previous commits.
While versions < 1.1.1 are not officially supported anymore, 1.0.2 might
still be in use because before 3.x that was the latest version with
official FIPS support (OpenSSL apparently also provides extended commercial
support for it).
The old API has been deprecated with OpenSSL 3 and direct access to the
state isn't possible via EVP API. In the future we might just remove this
implementation but we'd probably have to implement EAP-AKA' first, which
uses HMAC-SHA-256 with IKEv2's prf+ construct to derive keys instead
of this weird construct (plus what fips-prf builds around it) that's used
by EAP-AKA.
The HKDF-Expand() function defined in RFC 5869 is basically the same as
IKEv2's prf+(), so we can use the former to implement the latter.
However, we can only support HMAC-based PRFs this way, which should be
fine as others are rarely used.
There is a conflict between atexit() handlers registered by OpenSSL and
some executables (e.g. swanctl or pki) to deinitialize libstrongswan.
Because plugins are usually loaded after atexit() has been called, the
handler registered by OpenSSL will run before our handler. So when the
latter destroys the plugins it's a bad idea to try to access any OpenSSL
objects as they might already be invalid.
Fixes: f556fce16b ("openssl: Load "legacy" provider in OpenSSL 3 for algorithms like MD4, DES etc.")
Closesstrongswan/strongswan#921
We still require these algorithms for e.g. EAP-MSCHAPv2, so the option is
enabled, by default. To use other providers (e.g. fips or even custom
ones), the option can be disabled and the providers to load/activate can
be configured in openssl.cnf. For instance, the following has the same
effect as enabling the option:
openssl_conf = openssl_init
[openssl_init]
providers = providers
[providers]
default = activate
legacy = activate
[activate]
activate = yes
Determined by whether the library provides curves for it or not.
For instance, in the OpenSSL 3 FIPS provider the Brainpool curves are
not included. And in the Fedora package several weak curves are
explicitly patched out and the Brainpool curves are omitted even in
non-FIPS mode.
Andreas Steffen