From 5527a78ed96043d2c26e3271066c50b44dd7fc0b Mon Sep 17 00:00:00 2001 From: Benoît Ganne Date: Tue, 18 Jan 2022 15:56:41 +0100 Subject: ipsec: make pre-shared keys harder to misuse MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Using pre-shared keys is usually a bad idea, one should use eg. IKEv2 instead, but one does not always have the choice. For AES-CBC, the IV must be unpredictable (see NIST SP800-38a Appendix C) whereas for AES-CTR or AES-GCM, the IV should never be reused with the same key material (see NIST SP800-38a Appendix B and NIST SP800-38d section 8). If one uses pre-shared keys and VPP is restarted, the IV counter restarts at 0 and the same IVs are generated with the same pre-shared keys materials. To fix those issues we follow the recommendation from NIST SP800-38a and NIST SP800-38d: - we use a PRNG (not cryptographically secured) to generate IVs to avoid generating the same IV sequence between VPP restarts. The PRNG is chosen so that there is a low chance of generating the same sequence - for AES-CBC, the generated IV is encrypted as part of the message. This makes the (predictable) PRNG-generated IV unpredictable as it is encrypted with the secret key - for AES-CTR and GCM, we use the IV as-is as predictable IVs are fine Most of the changes in this patch are caused by the need to shoehorn an additional state of 2 u64 for the PRNG in the 1st cacheline of the SA object. Type: improvement Change-Id: I2af89c21ae4b2c4c33dd21aeffcfb79c13c9d84c Signed-off-by: Benoît Ganne --- src/vnet/ipsec/ah_decrypt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/vnet/ipsec/ah_decrypt.c') diff --git a/src/vnet/ipsec/ah_decrypt.c b/src/vnet/ipsec/ah_decrypt.c index ce4610dae6e..f20f620eb3c 100644 --- a/src/vnet/ipsec/ah_decrypt.c +++ b/src/vnet/ipsec/ah_decrypt.c @@ -155,7 +155,7 @@ ah_decrypt_inline (vlib_main_t * vm, thread_index, current_sa_index); } - if (PREDICT_FALSE (~0 == sa0->thread_index)) + if (PREDICT_FALSE ((u16) ~0 == sa0->thread_index)) { /* this is the first packet to use this SA, claim the SA * for this thread. this could happen simultaneously on -- cgit 1.2.3-korg