From 1455988efbe7f1632758f40f1d4c4dfaeea81b76 Mon Sep 17 00:00:00 2001 From: James Prestwood Date: Mon, 12 Aug 2024 10:16:49 -0700 Subject: [PATCH] sae: support default group for H2E This was seemingly trivial at face value but doing so ended up pointing out a bug with how group_retry is set when forcing the default group. Since group_retry is initialized to -1 the increment in the force_default_group block results in it being set to zero, which is actually group 20, not 19. This did not matter for hunt and peck, but H2E actually uses the retry value to index its pre-generated points which then breaks SAE if forcing the default group with H2E. To handle H2E and force_default_group, the group selection logic will always begin iterating the group array regardless of SAE type. --- src/sae.c | 41 ++++++++++++++++++----------------------- 1 file changed, 18 insertions(+), 23 deletions(-) diff --git a/src/sae.c b/src/sae.c index 9bce8faa..97c0af05 100644 --- a/src/sae.c +++ b/src/sae.c @@ -152,39 +152,34 @@ static int sae_choose_next_group(struct sae_sm *sm) { const unsigned int *ecc_groups = l_ecc_supported_ike_groups(); bool reset = sm->group_retry >= 0; + unsigned int group; - /* - * If this is a buggy AP in which group negotiation is broken use the - * default group 19 and fail if this is a retry. - */ - if (sm->sae_type == CRYPTO_SAE_LOOPING && sm->force_default_group) { - if (sm->group_retry != -1) { - l_warn("Forced default group but was rejected!"); - return -ENOENT; - } + /* Find the next group in the list */ + while ((group = ecc_groups[++sm->group_retry])) { + /* + * Forcing the default group; only choose group 19. If we have + * already passed 19 (due to a retry) we will exhaust all other + * groups and should fail. + */ + if (sm->force_default_group && group != 19) + continue; - sae_debug("Forcing default SAE group 19"); + /* Ensure the PT was derived for this group */ + if (sm->sae_type == CRYPTO_SAE_HASH_TO_ELEMENT && + !sm->handshake->ecc_sae_pts[sm->group_retry]) + continue; - sm->group_retry++; - sm->group = 19; - - goto get_curve; + break; } - do { - sm->group_retry++; + if (!group) + return -ENOENT; - if (ecc_groups[sm->group_retry] == 0) - return -ENOENT; - } while (sm->sae_type != CRYPTO_SAE_LOOPING && - !sm->handshake->ecc_sae_pts[sm->group_retry]); + sm->group = group; if (reset) sae_reset_state(sm); - sm->group = ecc_groups[sm->group_retry]; - -get_curve: sae_debug("Using group %u", sm->group); sm->curve = l_ecc_curve_from_ike_group(sm->group);