mirror of
https://github.com/openwrt/openwrt.git
synced 2024-12-23 15:32:33 +00:00
53 lines
1.9 KiB
Diff
53 lines
1.9 KiB
Diff
|
From 00a6cc73da61b03c146b6c341d0d1e572bcef432 Mon Sep 17 00:00:00 2001
|
||
|
From: Jouni Malinen <j@w1.fi>
|
||
|
Date: Mon, 24 Jun 2019 23:02:51 +0300
|
||
|
Subject: [PATCH 5/6] EAP-pwd: Run through prf result processing even if it >=
|
||
|
prime
|
||
|
|
||
|
This reduces differences in timing and memory access within the
|
||
|
hunting-and-pecking loop for ECC groups that have a prime that is not
|
||
|
close to a power of two (e.g., Brainpool curves).
|
||
|
|
||
|
Signed-off-by: Jouni Malinen <j@w1.fi>
|
||
|
(cherry picked from commit cd803299ca485eb857e37c88f973fccfbb8600e5)
|
||
|
---
|
||
|
src/eap_common/eap_pwd_common.c | 13 ++++++++++---
|
||
|
1 file changed, 10 insertions(+), 3 deletions(-)
|
||
|
|
||
|
--- a/src/eap_common/eap_pwd_common.c
|
||
|
+++ b/src/eap_common/eap_pwd_common.c
|
||
|
@@ -155,6 +155,8 @@ int compute_password_element(EAP_PWD_gro
|
||
|
struct crypto_bignum *x_candidate = NULL, *cofactor = NULL;
|
||
|
const struct crypto_bignum *prime;
|
||
|
u8 mask, found_ctr = 0, is_odd = 0;
|
||
|
+ int cmp_prime;
|
||
|
+ unsigned int in_range;
|
||
|
|
||
|
if (grp->pwe)
|
||
|
return -1;
|
||
|
@@ -247,8 +249,13 @@ int compute_password_element(EAP_PWD_gro
|
||
|
if (primebitlen % 8)
|
||
|
buf_shift_right(prfbuf, primebytelen,
|
||
|
8 - primebitlen % 8);
|
||
|
- if (const_time_memcmp(prfbuf, prime_bin, primebytelen) >= 0)
|
||
|
- continue;
|
||
|
+ cmp_prime = const_time_memcmp(prfbuf, prime_bin, primebytelen);
|
||
|
+ /* Create a const_time mask for selection based on prf result
|
||
|
+ * being smaller than prime. */
|
||
|
+ in_range = const_time_fill_msb((unsigned int) cmp_prime);
|
||
|
+ /* The algorithm description would skip the next steps if
|
||
|
+ * cmp_prime >= 0, but go through them regardless to minimize
|
||
|
+ * externally observable differences in behavior. */
|
||
|
|
||
|
crypto_bignum_deinit(x_candidate, 1);
|
||
|
x_candidate = crypto_bignum_init_set(prfbuf, primebytelen);
|
||
|
@@ -311,7 +318,7 @@ int compute_password_element(EAP_PWD_gro
|
||
|
goto fail;
|
||
|
mask = const_time_eq(res, check);
|
||
|
found_ctr = const_time_select_u8(found, found_ctr, ctr);
|
||
|
- found |= mask;
|
||
|
+ found |= mask & in_range;
|
||
|
}
|
||
|
if (found == 0) {
|
||
|
wpa_printf(MSG_INFO,
|