From f6a2f59574788aadd0ce323ad8ebe4d0c470672e Mon Sep 17 00:00:00 2001
From: Clemens Lang <cllang@redhat.com>
Date: Wed, 17 Aug 2022 12:56:29 -0400
Subject: [PATCH] Selectively disallow SHA1 signatures
For RHEL 9.0, we want to phase out SHA1. One of the steps to do that is
disabling SHA1 signatures. Introduce a new configuration option in the
alg_section named 'rh-allow-sha1-signatures'. This option defaults to
false. If set to false (or unset), 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.
For signatures created using the EVP_PKEY API, this is a best-effort
check that will deny signatures in cases where the digest algorithm is
known. This means, for example, that that following steps will still
work:
$> openssl dgst -sha1 -binary -out sha1 infile
$> openssl pkeyutl -inkey key.pem -sign -in sha1 -out sha1sig
$> openssl pkeyutl -inkey key.pem -verify -sigfile sha1sig -in sha1
whereas these will not:
$> openssl dgst -sha1 -binary -out sha1 infile
$> openssl pkeyutl -inkey kem.pem -sign -in sha1 -out sha1sig -pkeyopt digest:sha1
$> openssl pkeyutl -inkey kem.pem -verify -sigfile sha1sig -in sha1 -pkeyopt digest:sha1
This happens because in the first case, OpenSSL's signature
implementation does not know that it is signing a SHA1 hash (it could be
signing arbitrary data).
Resolves: rhbz#2031742
Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>
---
crypto/evp/evp_cnf.c | 13 ++++
crypto/evp/m_sigver.c | 77 +++++++++++++++++++
crypto/evp/pmeth_lib.c | 15 ++++
doc/man5/config.pod | 11 +++
include/internal/cryptlib.h | 3 +-
include/internal/sslconf.h | 4 +
providers/common/securitycheck.c | 20 +++++
providers/common/securitycheck_default.c | 9 ++-
providers/implementations/signature/dsa_sig.c | 11 ++-
.../implementations/signature/ecdsa_sig.c | 4 +
providers/implementations/signature/rsa_sig.c | 20 ++++-
ssl/t1_lib.c | 8 ++
util/libcrypto.num | 2 +
13 files changed, 188 insertions(+), 9 deletions(-)
diff --git a/crypto/evp/evp_cnf.c b/crypto/evp/evp_cnf.c
index 0e7fe64cf92e4b73b3bf873895e73fa9646df86d..b9d3b6d226ca07a65d972bb8505b7976a0d02572 100644
--- a/crypto/evp/evp_cnf.c
+++ b/crypto/evp/evp_cnf.c
@@ -10,6 +10,7 @@
#include <stdio.h>
#include <openssl/crypto.h>
#include "internal/cryptlib.h"
+#include "internal/sslconf.h"
#include <openssl/conf.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
@@ -57,6 +58,18 @@ static int alg_module_init(CONF_IMODULE *md, const CONF *cnf)
ERR_raise(ERR_LIB_EVP, EVP_R_SET_DEFAULT_PROPERTY_FAILURE);
return 0;
}
+ } else if (strcmp(oval->name, "rh-allow-sha1-signatures") == 0) {
+ int m;
+
+ /* Detailed error already reported. */
+ if (!X509V3_get_value_bool(oval, &m))
+ return 0;
+
+ if (!ossl_ctx_legacy_digest_signatures_allowed_set(
+ NCONF_get0_libctx((CONF *)cnf), m > 0, 0)) {
+ ERR_raise(ERR_LIB_EVP, EVP_R_SET_DEFAULT_PROPERTY_FAILURE);
+ return 0;
+ }
} else {
ERR_raise_data(ERR_LIB_EVP, EVP_R_UNKNOWN_OPTION,
"name=%s, value=%s", oval->name, oval->value);
diff --git a/crypto/evp/m_sigver.c b/crypto/evp/m_sigver.c
index 76a6814b424bec3479bdf61374f0178b9cd96ded..4b2f1fcfb886661d98460c240d542df2ccd5df13 100644
--- a/crypto/evp/m_sigver.c
+++ b/crypto/evp/m_sigver.c
@@ -16,6 +16,71 @@
#include "internal/numbers.h" /* includes SIZE_MAX */
#include "evp_local.h"
+typedef struct ossl_legacy_digest_signatures_st {
+ int allowed;
+} OSSL_LEGACY_DIGEST_SIGNATURES;
+
+static void ossl_ctx_legacy_digest_signatures_free(void *vldsigs)
+{
+ OSSL_LEGACY_DIGEST_SIGNATURES *ldsigs = vldsigs;
+
+ if (ldsigs != NULL) {
+ OPENSSL_free(ldsigs);
+ }
+}
+
+static void *ossl_ctx_legacy_digest_signatures_new(OSSL_LIB_CTX *ctx)
+{
+ return OPENSSL_zalloc(sizeof(OSSL_LEGACY_DIGEST_SIGNATURES));
+}
+
+static const OSSL_LIB_CTX_METHOD ossl_ctx_legacy_digest_signatures_method = {
+ OSSL_LIB_CTX_METHOD_DEFAULT_PRIORITY,
+ ossl_ctx_legacy_digest_signatures_new,
+ ossl_ctx_legacy_digest_signatures_free,
+};
+
+static OSSL_LEGACY_DIGEST_SIGNATURES *ossl_ctx_legacy_digest_signatures(
+ OSSL_LIB_CTX *libctx, int loadconfig)
+{
+#ifndef FIPS_MODULE
+ if (loadconfig && !OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL))
+ return 0;
+#endif
+
+ return ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_LEGACY_DIGEST_SIGNATURES,
+ &ossl_ctx_legacy_digest_signatures_method);
+}
+
+int ossl_ctx_legacy_digest_signatures_allowed(OSSL_LIB_CTX *libctx, int loadconfig)
+{
+ OSSL_LEGACY_DIGEST_SIGNATURES *ldsigs
+ = ossl_ctx_legacy_digest_signatures(libctx, loadconfig);
+
+#ifndef FIPS_MODULE
+ if (ossl_safe_getenv("OPENSSL_ENABLE_SHA1_SIGNATURES") != NULL)
+ /* used in tests */
+ return 1;
+#endif
+
+ return ldsigs != NULL ? ldsigs->allowed : 0;
+}
+
+int ossl_ctx_legacy_digest_signatures_allowed_set(OSSL_LIB_CTX *libctx, int allow,
+ int loadconfig)
+{
+ OSSL_LEGACY_DIGEST_SIGNATURES *ldsigs
+ = ossl_ctx_legacy_digest_signatures(libctx, loadconfig);
+
+ if (ldsigs == NULL) {
+ ERR_raise(ERR_LIB_EVP, ERR_R_INTERNAL_ERROR);
+ return 0;
+ }
+
+ ldsigs->allowed = allow;
+ return 1;
+}
+
#ifndef FIPS_MODULE
static int update(EVP_MD_CTX *ctx, const void *data, size_t datalen)
@@ -258,6 +323,18 @@ static int do_sigver_init(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
}
}
+ if (ctx->reqdigest != NULL
+ && !EVP_PKEY_is_a(locpctx->pkey, SN_hmac)
+ && !EVP_PKEY_is_a(locpctx->pkey, SN_tls1_prf)
+ && !EVP_PKEY_is_a(locpctx->pkey, SN_hkdf)) {
+ int mdnid = EVP_MD_nid(ctx->reqdigest);
+ if (!ossl_ctx_legacy_digest_signatures_allowed(locpctx->libctx, 0)
+ && (mdnid == NID_sha1 || mdnid == NID_md5_sha1)) {
+ ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_DIGEST);
+ goto err;
+ }
+ }
+
if (ver) {
if (signature->digest_verify_init == NULL) {
ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);
diff --git a/crypto/evp/pmeth_lib.c b/crypto/evp/pmeth_lib.c
index da367ed05fbe42abb328c6e23cafe99e76d26819..ee6edf1e85e71cdbe58bf7e9f443425dce100e43 100644
--- a/crypto/evp/pmeth_lib.c
+++ b/crypto/evp/pmeth_lib.c
@@ -33,6 +33,7 @@
#include "internal/ffc.h"
#include "internal/numbers.h"
#include "internal/provider.h"
+#include "internal/sslconf.h"
#include "evp_local.h"
#ifndef FIPS_MODULE
@@ -946,6 +947,20 @@ static int evp_pkey_ctx_set_md(EVP_PKEY_CTX *ctx, const EVP_MD *md,
return -2;
}
+ if (EVP_PKEY_CTX_IS_SIGNATURE_OP(ctx)
+ && md != NULL
+ && ctx->pkey != NULL
+ && !EVP_PKEY_is_a(ctx->pkey, SN_hmac)
+ && !EVP_PKEY_is_a(ctx->pkey, SN_tls1_prf)
+ && !EVP_PKEY_is_a(ctx->pkey, SN_hkdf)) {
+ int mdnid = EVP_MD_nid(md);
+ if ((mdnid == NID_sha1 || mdnid == NID_md5_sha1)
+ && !ossl_ctx_legacy_digest_signatures_allowed(ctx->libctx, 0)) {
+ ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_DIGEST);
+ return -1;
+ }
+ }
+
if (fallback)
return EVP_PKEY_CTX_ctrl(ctx, -1, op, ctrl, 0, (void *)(md));
diff --git a/doc/man5/config.pod b/doc/man5/config.pod
index a84113287c3d0edf6c67726aee7d8abb87401445..f1536258470563b4fe74f8d1e3db6d73ed316341 100644
--- a/doc/man5/config.pod
+++ b/doc/man5/config.pod
@@ -304,6 +304,17 @@ Within the algorithm properties section, the following names have meaning:
The value may be anything that is acceptable as a property query
string for EVP_set_default_properties().
+=item B<rh-allow-sha1-signatures>
+
+The value is a boolean that can be B<yes> or B<no>. If the value is not set,
+it behaves as if it was set to B<no>.
+
+When set to B<no>, any attempt to create or verify a signature with a SHA1
+digest will fail. For compatibility with older versions of OpenSSL, set this
+option to B<yes>. This setting also affects TLS, where signature algorithms
+that use SHA1 as digest will no longer be supported if this option is set to
+B<no>.
+
=item B<fips_mode> (deprecated)
The value is a boolean that can be B<yes> or B<no>. If the value is
diff --git a/include/internal/cryptlib.h b/include/internal/cryptlib.h
index 1291299b6e50ea129ba77c85bb0b21b0997e4494..e234341e6afd15f7108c7af453d6f2190c086b04 100644
--- a/include/internal/cryptlib.h
+++ b/include/internal/cryptlib.h
@@ -168,7 +168,8 @@ typedef struct ossl_ex_data_global_st {
# define OSSL_LIB_CTX_PROVIDER_CONF_INDEX 16
# define OSSL_LIB_CTX_BIO_CORE_INDEX 17
# define OSSL_LIB_CTX_CHILD_PROVIDER_INDEX 18
-# define OSSL_LIB_CTX_MAX_INDEXES 19
+# define OSSL_LIB_CTX_LEGACY_DIGEST_SIGNATURES 19
+# define OSSL_LIB_CTX_MAX_INDEXES 20
# define OSSL_LIB_CTX_METHOD_LOW_PRIORITY -1
# define OSSL_LIB_CTX_METHOD_DEFAULT_PRIORITY 0
diff --git a/include/internal/sslconf.h b/include/internal/sslconf.h
index fd7f7e333183dde57a283dab7372f9afb38c0eb4..05464b0655b20da2035f6781f44ac577e895fc8a 100644
--- a/include/internal/sslconf.h
+++ b/include/internal/sslconf.h
@@ -18,4 +18,8 @@ int conf_ssl_name_find(const char *name, size_t *idx);
void conf_ssl_get_cmd(const SSL_CONF_CMD *cmd, size_t idx, char **cmdstr,
char **arg);
+/* Methods to support disabling all signatures with legacy digests */
+int ossl_ctx_legacy_digest_signatures_allowed(OSSL_LIB_CTX *libctx, int loadconfig);
+int ossl_ctx_legacy_digest_signatures_allowed_set(OSSL_LIB_CTX *libctx, int allow,
+ int loadconfig);
#endif
diff --git a/providers/common/securitycheck.c b/providers/common/securitycheck.c
index 446ad6b4c11cf8dcad9dcb86df38816eff4bf772..9e47f5655957e661fa4f66f5e67a78c6c7d2fe5b 100644
--- a/providers/common/securitycheck.c
+++ b/providers/common/securitycheck.c
@@ -19,6 +19,7 @@
#include <openssl/core_names.h>
#include <openssl/obj_mac.h>
#include "prov/securitycheck.h"
+#include "internal/sslconf.h"
/*
* FIPS requires a minimum security strength of 112 bits (for encryption or
@@ -235,6 +236,15 @@ int ossl_digest_get_approved_nid_with_sha1(OSSL_LIB_CTX *ctx, const EVP_MD *md,
mdnid = -1; /* disallowed by security checks */
}
# endif /* OPENSSL_NO_FIPS_SECURITYCHECKS */
+
+#ifndef FIPS_MODULE
+ if (!ossl_ctx_legacy_digest_signatures_allowed(ctx, 0))
+ /* SHA1 is globally disabled, check whether we want to locally allow
+ * it. */
+ if (mdnid == NID_sha1 && !sha1_allowed)
+ mdnid = -1;
+#endif
+
return mdnid;
}
@@ -244,5 +254,15 @@ int ossl_digest_is_allowed(OSSL_LIB_CTX *ctx, const EVP_MD *md)
if (ossl_securitycheck_enabled(ctx))
return ossl_digest_get_approved_nid(md) != NID_undef;
# endif /* OPENSSL_NO_FIPS_SECURITYCHECKS */
+
+#ifndef FIPS_MODULE
+ {
+ int mdnid = EVP_MD_nid(md);
+ if ((mdnid == NID_sha1 || mdnid == NID_md5_sha1)
+ && !ossl_ctx_legacy_digest_signatures_allowed(ctx, 0))
+ return 0;
+ }
+#endif
+
return 1;
}
diff --git a/providers/common/securitycheck_default.c b/providers/common/securitycheck_default.c
index de7f0d3a0a5718bd06a55d3d92236c27ffb7d0d5..ce54a94fbc9b3f48052c0bd5acf5b0aa349c4e91 100644
--- a/providers/common/securitycheck_default.c
+++ b/providers/common/securitycheck_default.c
@@ -15,6 +15,7 @@
#include <openssl/obj_mac.h>
#include "prov/securitycheck.h"
#include "internal/nelem.h"
+#include "internal/sslconf.h"
/* Disable the security checks in the default provider */
int ossl_securitycheck_enabled(OSSL_LIB_CTX *libctx)
@@ -23,9 +24,10 @@ int ossl_securitycheck_enabled(OSSL_LIB_CTX *libctx)
}
int ossl_digest_rsa_sign_get_md_nid(OSSL_LIB_CTX *ctx, const EVP_MD *md,
- ossl_unused int sha1_allowed)
+ int sha1_allowed)
{
int mdnid;
+ int ldsigs_allowed;
static const OSSL_ITEM name_to_nid[] = {
{ NID_md5, OSSL_DIGEST_NAME_MD5 },
@@ -36,8 +38,11 @@ int ossl_digest_rsa_sign_get_md_nid(OSSL_LIB_CTX *ctx, const EVP_MD *md,
{ NID_ripemd160, OSSL_DIGEST_NAME_RIPEMD160 },
};
- mdnid = ossl_digest_get_approved_nid_with_sha1(ctx, md, 1);
+ ldsigs_allowed = ossl_ctx_legacy_digest_signatures_allowed(ctx, 0);
+ mdnid = ossl_digest_get_approved_nid_with_sha1(ctx, md, sha1_allowed || ldsigs_allowed);
if (mdnid == NID_undef)
mdnid = ossl_digest_md_to_nid(md, name_to_nid, OSSL_NELEM(name_to_nid));
+ if (mdnid == NID_md5_sha1 && !ldsigs_allowed)
+ mdnid = -1;
return mdnid;
}
diff --git a/providers/implementations/signature/dsa_sig.c b/providers/implementations/signature/dsa_sig.c
index 28fd7c498e9922b6fabd1fafa452afe7ca3734ec..fa3822f39fd14a16c761b316e276c68868f35c7d 100644
--- a/providers/implementations/signature/dsa_sig.c
+++ b/providers/implementations/signature/dsa_sig.c
@@ -124,12 +124,17 @@ static int dsa_setup_md(PROV_DSA_CTX *ctx,
mdprops = ctx->propq;
if (mdname != NULL) {
- int sha1_allowed = (ctx->operation != EVP_PKEY_OP_SIGN);
WPACKET pkt;
EVP_MD *md = EVP_MD_fetch(ctx->libctx, mdname, mdprops);
- int md_nid = ossl_digest_get_approved_nid_with_sha1(ctx->libctx, md,
- sha1_allowed);
+ int md_nid;
size_t mdname_len = strlen(mdname);
+#ifdef FIPS_MODULE
+ int sha1_allowed = (ctx->operation != EVP_PKEY_OP_SIGN);
+#else
+ int sha1_allowed = 0;
+#endif
+ md_nid = ossl_digest_get_approved_nid_with_sha1(ctx->libctx, md,
+ sha1_allowed);
if (md == NULL || md_nid < 0) {
if (md == NULL)
diff --git a/providers/implementations/signature/ecdsa_sig.c b/providers/implementations/signature/ecdsa_sig.c
index 865d49d1004f0031c82c24c218828a7d9c7269c6..99b228e82c408171bb2458244d2cf763e32a19fb 100644
--- a/providers/implementations/signature/ecdsa_sig.c
+++ b/providers/implementations/signature/ecdsa_sig.c
@@ -237,7 +237,11 @@ static int ecdsa_setup_md(PROV_ECDSA_CTX *ctx, const char *mdname,
"%s could not be fetched", mdname);
return 0;
}
+#ifdef FIPS_MODULE
sha1_allowed = (ctx->operation != EVP_PKEY_OP_SIGN);
+#else
+ sha1_allowed = 0;
+#endif
md_nid = ossl_digest_get_approved_nid_with_sha1(ctx->libctx, md,
sha1_allowed);
if (md_nid < 0) {
diff --git a/providers/implementations/signature/rsa_sig.c b/providers/implementations/signature/rsa_sig.c
index 7023a866131e38c214ac7326fdd83274dab81833..f66d7705c35add553694c5808b51d5696f678ee7 100644
--- a/providers/implementations/signature/rsa_sig.c
+++ b/providers/implementations/signature/rsa_sig.c
@@ -25,6 +25,7 @@
#include "internal/cryptlib.h"
#include "internal/nelem.h"
#include "internal/sizes.h"
+#include "internal/sslconf.h"
#include "crypto/rsa.h"
#include "prov/providercommon.h"
#include "prov/implementations.h"
@@ -33,6 +34,7 @@
#include "prov/securitycheck.h"
#define RSA_DEFAULT_DIGEST_NAME OSSL_DIGEST_NAME_SHA1
+#define RSA_DEFAULT_DIGEST_NAME_NONLEGACY OSSL_DIGEST_NAME_SHA2_256
static OSSL_FUNC_signature_newctx_fn rsa_newctx;
static OSSL_FUNC_signature_sign_init_fn rsa_sign_init;
@@ -288,10 +290,15 @@ static int rsa_setup_md(PROV_RSA_CTX *ctx, const char *mdname,
if (mdname != NULL) {
EVP_MD *md = EVP_MD_fetch(ctx->libctx, mdname, mdprops);
+ int md_nid;
+ size_t mdname_len = strlen(mdname);
+#ifdef FIPS_MODULE
int sha1_allowed = (ctx->operation != EVP_PKEY_OP_SIGN);
- int md_nid = ossl_digest_rsa_sign_get_md_nid(ctx->libctx, md,
+#else
+ int sha1_allowed = 0;
+#endif
+ md_nid = ossl_digest_rsa_sign_get_md_nid(ctx->libctx, md,
sha1_allowed);
- size_t mdname_len = strlen(mdname);
if (md == NULL
|| md_nid <= 0
@@ -1347,8 +1354,15 @@ static int rsa_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
prsactx->pad_mode = pad_mode;
if (prsactx->md == NULL && pmdname == NULL
- && pad_mode == RSA_PKCS1_PSS_PADDING)
+ && pad_mode == RSA_PKCS1_PSS_PADDING) {
pmdname = RSA_DEFAULT_DIGEST_NAME;
+#ifndef FIPS_MODULE
+ if (!ossl_ctx_legacy_digest_signatures_allowed(prsactx->libctx, 0)) {
+ pmdname = RSA_DEFAULT_DIGEST_NAME_NONLEGACY;
+ }
+#endif
+ }
+
if (pmgf1mdname != NULL
&& !rsa_setup_mgf1_md(prsactx, pmgf1mdname, pmgf1mdprops))
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 48a0b7f6e5908e62b433a306c49a3f2ff7e8df76..909e38c2fe88324884a939b583fd7f43d01f3920 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -20,6 +20,7 @@
#include <openssl/bn.h>
#include <openssl/provider.h>
#include <openssl/param_build.h>
+#include "internal/sslconf.h"
#include "internal/nelem.h"
#include "internal/sizes.h"
#include "internal/tlsgroups.h"
@@ -1150,11 +1151,13 @@ int ssl_setup_sig_algs(SSL_CTX *ctx)
= OPENSSL_malloc(sizeof(*lu) * OSSL_NELEM(sigalg_lookup_tbl));
EVP_PKEY *tmpkey = EVP_PKEY_new();
int ret = 0;
+ int ldsigs_allowed;
if (cache == NULL || tmpkey == NULL)
goto err;
ERR_set_mark();
+ ldsigs_allowed = ossl_ctx_legacy_digest_signatures_allowed(ctx->libctx, 0);
for (i = 0, lu = sigalg_lookup_tbl;
i < OSSL_NELEM(sigalg_lookup_tbl); lu++, i++) {
EVP_PKEY_CTX *pctx;
@@ -1174,6 +1177,11 @@ int ssl_setup_sig_algs(SSL_CTX *ctx)
cache[i].enabled = 0;
continue;
}
+ if ((lu->hash == NID_sha1 || lu->hash == NID_md5_sha1)
+ && !ldsigs_allowed) {
+ cache[i].enabled = 0;
+ continue;
+ }
if (!EVP_PKEY_set_type(tmpkey, lu->sig)) {
cache[i].enabled = 0;
diff --git a/util/libcrypto.num b/util/libcrypto.num
index d94f406606132690d4744e470d98eff377d87699..07ae9a21ec979028eb78feaee4cadb801b790caf 100644
--- a/util/libcrypto.num
+++ b/util/libcrypto.num
@@ -5428,3 +5428,5 @@ EVP_PKEY_CTX_get0_provider 5555 3_0_0 EXIST::FUNCTION:
OPENSSL_strcasecmp 5556 3_0_3 EXIST::FUNCTION:
OPENSSL_strncasecmp 5557 3_0_3 EXIST::FUNCTION:
ossl_safe_getenv ? 3_0_0 EXIST::FUNCTION:
+ossl_ctx_legacy_digest_signatures_allowed ? 3_0_1 EXIST::FUNCTION:
+ossl_ctx_legacy_digest_signatures_allowed_set ? 3_0_1 EXIST::FUNCTION:
--
2.37.2