72 lines
2.6 KiB
Diff
72 lines
2.6 KiB
Diff
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From fc9867c1e03c22ebf56943be205202e576aabf23 Mon Sep 17 00:00:00 2001
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From: Matt Caswell <matt@openssl.org>
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Date: Thu, 6 Jul 2023 16:36:35 +0100
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Subject: [PATCH] Fix DH_check() excessive time with over sized modulus
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The DH_check() function checks numerous aspects of the key or parameters
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that have been supplied. Some of those checks use the supplied modulus
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value even if it is excessively large.
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There is already a maximum DH modulus size (10,000 bits) over which
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OpenSSL will not generate or derive keys. DH_check() will however still
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perform various tests for validity on such a large modulus. We introduce a
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new maximum (32,768) over which DH_check() will just fail.
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An application that calls DH_check() and supplies a key or parameters
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obtained from an untrusted source could be vulnerable to a Denial of
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Service attack.
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The function DH_check() is itself called by a number of other OpenSSL
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functions. An application calling any of those other functions may
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similarly be affected. The other functions affected by this are
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DH_check_ex() and EVP_PKEY_param_check().
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CVE-2023-3446
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Reviewed-by: Paul Dale <pauli@openssl.org>
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Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
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Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
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Reviewed-by: Tomas Mraz <tomas@openssl.org>
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(Merged from https://github.com/openssl/openssl/pull/21451)
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(cherry picked from commit 9e0094e2aa1b3428a12d5095132f133c078d3c3d)
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---
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crypto/dh/dh_check.c | 6 ++++++
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include/openssl/dh.h | 6 +++++-
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2 files changed, 11 insertions(+), 1 deletion(-)
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diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c
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index 0b391910d6b3..84a926998e9b 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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@@ -152,6 +152,12 @@ int DH_check(const DH *dh, int *ret)
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if (nid != NID_undef)
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return 1;
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+ /* Don't do any checks at all with an excessively large modulus */
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+ if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) {
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+ ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
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+ return 0;
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+ }
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+
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if (!DH_check_params(dh, ret))
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return 0;
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diff --git a/include/openssl/dh.h b/include/openssl/dh.h
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index ec5a493da129..499f9f7109dd 100644
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--- a/include/openssl/dh.h
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+++ b/include/openssl/dh.h
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@@ -92,7 +92,11 @@ int EVP_PKEY_CTX_get0_dh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char **ukm);
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# include <openssl/dherr.h>
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# ifndef OPENSSL_DH_MAX_MODULUS_BITS
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-# define OPENSSL_DH_MAX_MODULUS_BITS 10000
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+# define OPENSSL_DH_MAX_MODULUS_BITS 10000
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+# endif
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+
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+# ifndef OPENSSL_DH_CHECK_MAX_MODULUS_BITS
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+# define OPENSSL_DH_CHECK_MAX_MODULUS_BITS 32768
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# endif
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# define OPENSSL_DH_FIPS_MIN_MODULUS_BITS 1024
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