On Thu, Apr 23, 2015 at 11:26:20AM +0800, Herbert Xu wrote: > Hi: > > It looks like our IPsec implementations of CCM and GCM are buggy > in that they don't include the IV in the authentication calculation. Seems like crypto_rfc4106_crypt() passes the associated data it got from ESP directly to gcm, without chaining with the IV. > > This definitely breaks interoperability with anyone who implements > them correctly. The fact that there have been no reports on this > probably means that nobody has run into this in the field yet. > > On the security side, this is probably not a big deal for CCM > because it always verifies the authentication tag after decryption. > But for GCM this may be a DoS issue as an attacker could modify > the IV without triggering the authentication check and thus cause > an unnecessary decryption. For both CCM and GCM this will result > in random data injected as a packet into the network stack which > hopefully will be dropped. > > In order to fix this without breaking backwards compatibility, > my plan is to introduce new templates such as rfc4106v2 which > implement the RFC correctly. The existing templates will be > retained so that current users aren't broken by the fix. Adding a second template for the correct implementation is probaply the only thing that we can do if we don't want to break backwards compatibility. But maybe we can add a warning to the old implementation, such that users notice that they use a broken version. -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
