61 lines
1.8 KiB
Diff
61 lines
1.8 KiB
Diff
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From 91ddeba0f2269b017dc06c46c993a788974b1aa5 Mon Sep 17 00:00:00 2001
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From: Tomas Mraz <tomas@openssl.org>
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Date: Fri, 21 Jul 2023 11:39:41 +0200
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Subject: [PATCH] DH_check(): Do not try checking q properties if it is
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obviously invalid
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If |q| >= |p| then the q value is obviously wrong as q
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is supposed to be a prime divisor of p-1.
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We check if p is overly large so this added test implies that
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q is not large either when performing subsequent tests using that
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q value.
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Otherwise if it is too large these additional checks of the q value
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such as the primality test can then trigger DoS by doing overly long
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computations.
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Fixes CVE-2023-3817
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Reviewed-by: Paul Dale <pauli@openssl.org>
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Reviewed-by: Matt Caswell <matt@openssl.org>
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(Merged from https://github.com/openssl/openssl/pull/21551)
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Upstream-Status: Backport [91ddeba0f2269b017dc06c46c993a788974b1aa5]
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---
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crypto/dh/dh_check.c | 11 +++++++++--
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1 file changed, 9 insertions(+), 2 deletions(-)
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diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c
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index 2001d2e7cb..9ae96991eb 100644
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--- a/crypto/dh/dh_check.c
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+++ b/crypto/dh/dh_check.c
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@@ -105,7 +105,7 @@ int DH_check_ex(const DH *dh)
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/* Note: according to documentation - this only checks the params */
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int DH_check(const DH *dh, int *ret)
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{
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- int ok = 0, r;
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+ int ok = 0, r, q_good = 0;
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BN_CTX *ctx = NULL;
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BIGNUM *t1 = NULL, *t2 = NULL;
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@@ -130,7 +130,14 @@ int DH_check(const DH *dh, int *ret)
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if (t2 == NULL)
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goto err;
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- if (dh->q) {
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+ if (dh->q != NULL) {
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+ if (BN_ucmp(dh->p, dh->q) > 0)
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+ q_good = 1;
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+ else
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+ *ret |= DH_CHECK_INVALID_Q_VALUE;
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+ }
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+
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+ if (q_good) {
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if (BN_cmp(dh->g, BN_value_one()) <= 0)
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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else if (BN_cmp(dh->g, dh->p) >= 0)
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--
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2.41.0
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