forked from rpms/openssl
432cfa2baa
NOTE: This patch is ported from CentOS 9 / RHEL 9, where it defaults to denying SHA1 signatures. On Fedora, the default is – for now – to allow SHA1 signatures. In order to phase out SHA1 signatures, introduce a new configuration option in the alg_section named 'rh-allow-sha1-signatures'. This option defaults to true. If set to false, any signature creation or verification operations that involve SHA1 as digest will fail. This also affects TLS, where the signature_algorithms extension of any ClientHello message sent by OpenSSL will no longer include signatures with the SHA1 digest if rh-allow-sha1-signatures is false. For servers that request a client certificate, the same also applies for CertificateRequest messages sent by them. Resolves: rhbz#2070977 Related: rhbz#2031742, rhbz#2062640 Signed-off-by: Clemens Lang <cllang@redhat.com>
218 lines
8.4 KiB
Diff
218 lines
8.4 KiB
Diff
From f695f140255f9b564cac4d5e9e38ba27ec927256 Mon Sep 17 00:00:00 2001
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From: Clemens Lang <cllang@redhat.com>
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Date: Tue, 1 Mar 2022 15:44:18 +0100
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Subject: [PATCH 2/2] Allow SHA1 in seclevel 1 if rh-allow-sha1-signatures =
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yes
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NOTE: This patch is ported from CentOS 9 / RHEL 9, where it allows SHA1
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in seclevel 2 if rh-allow-sha1-signatures = yes. This was chosen because
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on CentOS 9 and RHEL 9, the LEGACY crypto policy sets the security level
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to 2.
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On Fedora 35 (with OpenSSL 1.1) the legacy crypto policy uses security
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level 1. Because Fedora 36 supports both OpenSSL 1.1 and OpenSSL 3, and
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we want the legacy crypto policy to allow SHA-1 in TLS, the only option
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to make this happen consistently in both OpenSSL 1.1 and OpenSSL 3 is
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SECLEVEL=1 (which will allow SHA-1 in OpenSSL 1.1) and this change to
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allow SHA-1 in SECLEVEL=1 with rh-allow-sha1-signatures = yes (which
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will allow SHA-1 in OpenSSL 3).
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The change from CentOS 9 / RHEL 9 cannot be applied unmodified, because
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rh-allow-sha1-signatures will default to yes in Fedora (according to our
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current plans including until F38), and the security level in the
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DEFAULT crypto policy is 2, i.e., the unmodified change would weaken the
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default configuration.
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Related: rhbz#2055796
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Related: rhbz#2070977
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---
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crypto/x509/x509_vfy.c | 19 ++++++++++-
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doc/man5/config.pod | 7 ++++
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ssl/t1_lib.c | 64 ++++++++++++++++++++++++++++-------
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test/recipes/25-test_verify.t | 4 +--
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4 files changed, 78 insertions(+), 16 deletions(-)
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diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c
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index 2f175ca517..60aa26f552 100644
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--- a/crypto/x509/x509_vfy.c
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+++ b/crypto/x509/x509_vfy.c
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@@ -25,6 +25,7 @@
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#include <openssl/objects.h>
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#include <openssl/core_names.h>
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#include "internal/dane.h"
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+#include "internal/sslconf.h"
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#include "crypto/x509.h"
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#include "x509_local.h"
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@@ -3441,14 +3442,30 @@ static int check_sig_level(X509_STORE_CTX *ctx, X509 *cert)
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{
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int secbits = -1;
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int level = ctx->param->auth_level;
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+ int nid;
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+ OSSL_LIB_CTX *libctx = NULL;
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if (level <= 0)
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return 1;
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if (level > NUM_AUTH_LEVELS)
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level = NUM_AUTH_LEVELS;
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- if (!X509_get_signature_info(cert, NULL, NULL, &secbits, NULL))
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+ if (ctx->libctx)
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+ libctx = ctx->libctx;
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+ else if (cert->libctx)
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+ libctx = cert->libctx;
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+ else
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+ libctx = OSSL_LIB_CTX_get0_global_default();
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+
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+ if (!X509_get_signature_info(cert, &nid, NULL, &secbits, NULL))
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return 0;
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+ if (nid == NID_sha1
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+ && ossl_ctx_legacy_digest_signatures_allowed(libctx, 0)
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+ && ctx->param->auth_level < 2)
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+ /* When rh-allow-sha1-signatures = yes and security level <= 1,
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+ * explicitly allow SHA1 for backwards compatibility. */
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+ return 1;
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+
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return secbits >= minbits_table[level - 1];
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}
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diff --git a/doc/man5/config.pod b/doc/man5/config.pod
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index 0c9110d28a..02e7ca706f 100644
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--- a/doc/man5/config.pod
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+++ b/doc/man5/config.pod
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@@ -309,6 +309,13 @@ this option is set to B<no>. Because TLS 1.1 or lower use MD5-SHA1 as
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pseudorandom function (PRF) to derive key material, disabling
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B<rh-allow-sha1-signatures> requires the use of TLS 1.2 or newer.
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+Note that enabling B<rh-allow-sha1-signatures> will allow TLS signature
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+algorithms that use SHA1 in security level 1, despite the definition of
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+security level 1 of FIXME bits of security, which SHA1 does not meet. This
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+allows using SHA1 in TLS in the LEGACY crypto-policy on Fedora without
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+requiring to set the security level to 0, which would include further insecure
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+algorithms.
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+
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=item B<fips_mode> (deprecated)
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The value is a boolean that can be B<yes> or B<no>. If the value is
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diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
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index dcd487ec2e..e47ddf56f1 100644
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--- a/ssl/t1_lib.c
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+++ b/ssl/t1_lib.c
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@@ -20,6 +20,7 @@
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#include <openssl/bn.h>
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#include <openssl/provider.h>
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#include <openssl/param_build.h>
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+#include "crypto/x509.h"
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#include "internal/sslconf.h"
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#include "internal/nelem.h"
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#include "internal/sizes.h"
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@@ -1561,19 +1562,27 @@ int tls12_check_peer_sigalg(SSL *s, uint16_t sig, EVP_PKEY *pkey)
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SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_R_UNKNOWN_DIGEST);
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return 0;
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}
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- /*
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- * Make sure security callback allows algorithm. For historical
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- * reasons we have to pass the sigalg as a two byte char array.
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- */
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- sigalgstr[0] = (sig >> 8) & 0xff;
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- sigalgstr[1] = sig & 0xff;
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- secbits = sigalg_security_bits(s->ctx, lu);
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- if (secbits == 0 ||
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- !ssl_security(s, SSL_SECOP_SIGALG_CHECK, secbits,
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- md != NULL ? EVP_MD_get_type(md) : NID_undef,
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- (void *)sigalgstr)) {
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- SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_R_WRONG_SIGNATURE_TYPE);
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- return 0;
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+
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+ if (lu->hash == NID_sha1
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+ && ossl_ctx_legacy_digest_signatures_allowed(s->ctx->libctx, 0)
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+ && SSL_get_security_level(s) < 2) {
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+ /* when rh-allow-sha1-signatures = yes and security level <= 1,
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+ * explicitly allow SHA1 for backwards compatibility */
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+ } else {
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+ /*
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+ * Make sure security callback allows algorithm. For historical
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+ * reasons we have to pass the sigalg as a two byte char array.
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+ */
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+ sigalgstr[0] = (sig >> 8) & 0xff;
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+ sigalgstr[1] = sig & 0xff;
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+ secbits = sigalg_security_bits(s->ctx, lu);
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+ if (secbits == 0 ||
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+ !ssl_security(s, SSL_SECOP_SIGALG_CHECK, secbits,
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+ md != NULL ? EVP_MD_get_type(md) : NID_undef,
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+ (void *)sigalgstr)) {
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+ SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_R_WRONG_SIGNATURE_TYPE);
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+ return 0;
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+ }
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}
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/* Store the sigalg the peer uses */
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s->s3.tmp.peer_sigalg = lu;
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@@ -2106,6 +2115,14 @@ static int tls12_sigalg_allowed(const SSL *s, int op, const SIGALG_LOOKUP *lu)
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}
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}
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+ if (lu->hash == NID_sha1
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+ && ossl_ctx_legacy_digest_signatures_allowed(s->ctx->libctx, 0)
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+ && SSL_get_security_level(s) < 2) {
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+ /* when rh-allow-sha1-signatures = yes and security level <= 1,
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+ * explicitly allow SHA1 for backwards compatibility */
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+ return 1;
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+ }
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+
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/* Finally see if security callback allows it */
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secbits = sigalg_security_bits(s->ctx, lu);
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sigalgstr[0] = (lu->sigalg >> 8) & 0xff;
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@@ -2977,6 +2994,8 @@ static int ssl_security_cert_sig(SSL *s, SSL_CTX *ctx, X509 *x, int op)
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{
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/* Lookup signature algorithm digest */
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int secbits, nid, pknid;
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+ OSSL_LIB_CTX *libctx = NULL;
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+
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/* Don't check signature if self signed */
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if ((X509_get_extension_flags(x) & EXFLAG_SS) != 0)
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return 1;
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@@ -2985,6 +3004,25 @@ static int ssl_security_cert_sig(SSL *s, SSL_CTX *ctx, X509 *x, int op)
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/* If digest NID not defined use signature NID */
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if (nid == NID_undef)
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nid = pknid;
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+
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+ if (x && x->libctx)
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+ libctx = x->libctx;
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+ else if (ctx && ctx->libctx)
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+ libctx = ctx->libctx;
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+ else if (s && s->ctx && s->ctx->libctx)
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+ libctx = s->ctx->libctx;
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+ else
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+ libctx = OSSL_LIB_CTX_get0_global_default();
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+
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+ if (nid == NID_sha1
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+ && ossl_ctx_legacy_digest_signatures_allowed(libctx, 0)
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+ && ((s != NULL && SSL_get_security_level(s) < 2)
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+ || (ctx != NULL && SSL_CTX_get_security_level(ctx) < 2)
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+ ))
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+ /* When rh-allow-sha1-signatures = yes and security level <= 1,
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+ * explicitly allow SHA1 for backwards compatibility. */
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+ return 1;
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+
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if (s)
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return ssl_security(s, op, secbits, nid, x);
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else
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diff --git a/test/recipes/25-test_verify.t b/test/recipes/25-test_verify.t
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index 700bbd849c..280477bc9d 100644
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--- a/test/recipes/25-test_verify.t
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+++ b/test/recipes/25-test_verify.t
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@@ -387,8 +387,8 @@ ok(verify("ee-pss-sha1-cert", "", ["root-cert"], ["ca-cert"], "-auth_level", "0"
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ok(verify("ee-pss-sha256-cert", "", ["root-cert"], ["ca-cert"], ),
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"CA with PSS signature using SHA256");
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-ok(!verify("ee-pss-sha1-cert", "", ["root-cert"], ["ca-cert"], "-auth_level", "1"),
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- "Reject PSS signature using SHA1 and auth level 1");
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+ok(!verify("ee-pss-sha1-cert", "", ["root-cert"], ["ca-cert"], "-auth_level", "2"),
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+ "Reject PSS signature using SHA1 and auth level 2");
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ok(verify("ee-pss-sha256-cert", "", ["root-cert"], ["ca-cert"], "-auth_level", "2"),
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"PSS signature using SHA256 and auth level 2");
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--
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2.35.1
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