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openssl/0053-Add-SHA1-probes.patch
Clemens Lang efdb8c60a3 Allow MD5-SHA1 in LEGACY c-p to fix TLS 1.0 
Fedora supports TLS down to 1.0 in LEGACY crypto-policy, but TLS 1.0
defaults to rsa_pkcs1_md5_sha1 with RSA certificates by default.
However, MD5-SHA1 would require SECLEVEL=0, because its 67 bits of
security do not meet SECLEVEL=1's requirement of 80 bits.

Instead of setting SECLEVEL to 0 in the LEGACY crypto-policy (which
would include all algorithms, regardless of their security level), allow
MD5-SHA1 if rh-allow-sha1-signatures is yes and SECLEVEL is 1.

Related: rhbz#2069239
2022-04-27 12:24:38 +02:00

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From 428369896db1656af748a67bb36fba039e7b39ad Mon Sep 17 00:00:00 2001
From: Clemens Lang <cllang@redhat.com>
Date: Mon, 25 Apr 2022 15:21:46 +0200
Subject: [PATCH] Instrument SHA-1 signatures with USDT probes
In order to discover remaining uses of SHA-1 in signatures without
forcefully breaking the code paths, add USDT probes that can be queried
with systemtap at runtime.
This should allow identifying components that still use SHA-1 signatures
in production so that they can be transitioned to more modern hash
algorithms.
---
crypto/evp/m_sigver.c | 13 +++++++++----
crypto/evp/pmeth_lib.c | 13 +++++++++----
crypto/x509/x509_vfy.c | 6 +++++-
providers/common/securitycheck.c | 22 +++++++++++++++-------
providers/common/securitycheck_default.c | 13 +++++++++++--
ssl/t1_lib.c | 8 +++++++-
6 files changed, 56 insertions(+), 19 deletions(-)
diff --git a/crypto/evp/m_sigver.c b/crypto/evp/m_sigver.c
index 8da2183ce0..c17cdfa5d5 100644
--- a/crypto/evp/m_sigver.c
+++ b/crypto/evp/m_sigver.c
@@ -16,6 +16,8 @@
#include "internal/numbers.h" /* includes SIZE_MAX */
#include "evp_local.h"
+#include <sys/sdt.h>
+
typedef struct ossl_legacy_digest_signatures_st {
int allowed;
} OSSL_LEGACY_DIGEST_SIGNATURES;
@@ -336,10 +338,13 @@ static int do_sigver_init(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
&& !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 (mdnid == NID_sha1 || mdnid == NID_md5_sha1) {
+ if (!ossl_ctx_legacy_digest_signatures_allowed(locpctx->libctx, 0)) {
+ ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_DIGEST);
+ goto err;
+ } else {
+ DTRACE_PROBE1(libcrypto, fedora_do_sigver_init_1, mdnid);
+ }
}
}
diff --git a/crypto/evp/pmeth_lib.c b/crypto/evp/pmeth_lib.c
index b96f148c0d..54fcf24945 100644
--- a/crypto/evp/pmeth_lib.c
+++ b/crypto/evp/pmeth_lib.c
@@ -37,6 +37,8 @@
#include "internal/sslconf.h"
#include "evp_local.h"
+#include <sys/sdt.h>
+
#ifndef FIPS_MODULE
static int evp_pkey_ctx_store_cached_data(EVP_PKEY_CTX *ctx,
@@ -956,10 +958,13 @@ static int evp_pkey_ctx_set_md(EVP_PKEY_CTX *ctx, const EVP_MD *md,
&& !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 (mdnid == NID_sha1 || mdnid == NID_md5_sha1) {
+ if (!ossl_ctx_legacy_digest_signatures_allowed(ctx->libctx, 0)) {
+ ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_DIGEST);
+ return -1;
+ } else {
+ DTRACE_PROBE1(libcrypto, fedora_evp_pkey_ctx_set_md_1, mdnid);
+ }
}
}
diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c
index bf0c608839..78638ce80e 100644
--- a/crypto/x509/x509_vfy.c
+++ b/crypto/x509/x509_vfy.c
@@ -29,6 +29,8 @@
#include "crypto/x509.h"
#include "x509_local.h"
+#include <sys/sdt.h>
+
/* CRL score values */
#define CRL_SCORE_NOCRITICAL 0x100 /* No unhandled critical extensions */
@@ -3462,11 +3464,13 @@ static int check_sig_level(X509_STORE_CTX *ctx, X509 *cert)
if ((nid == NID_sha1 || nid == NID_md5_sha1)
&& ossl_ctx_legacy_digest_signatures_allowed(libctx, 0)
- && ctx->param->auth_level < 2)
+ && ctx->param->auth_level < 2) {
+ DTRACE_PROBE1(libcrypto, fedora_check_sig_level_1, nid);
/* When rh-allow-sha1-signatures = yes and security level <= 1,
* explicitly allow SHA1 for backwards compatibility. Also allow
* MD5-SHA1 because TLS 1.0 is still supported, which uses it. */
return 1;
+ }
return secbits >= minbits_table[level - 1];
}
diff --git a/providers/common/securitycheck.c b/providers/common/securitycheck.c
index e534ad0a5f..bf496450cf 100644
--- a/providers/common/securitycheck.c
+++ b/providers/common/securitycheck.c
@@ -21,6 +21,8 @@
#include "prov/securitycheck.h"
#include "internal/sslconf.h"
+#include <sys/sdt.h>
+
/*
* FIPS requires a minimum security strength of 112 bits (for encryption or
* signing), and for legacy purposes 80 bits (for decryption or verifying).
@@ -238,11 +240,14 @@ int ossl_digest_get_approved_nid_with_sha1(OSSL_LIB_CTX *ctx, const EVP_MD *md,
# 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)
+ if (mdnid == NID_sha1 && !sha1_allowed) {
+ if (!ossl_ctx_legacy_digest_signatures_allowed(ctx, 0))
+ /* SHA1 is globally disabled, check whether we want to locally allow
+ * it. */
mdnid = -1;
+ else
+ DTRACE_PROBE1(libcrypto, fedora_ossl_digest_get_approved_nid_with_sha1_1, mdnid);
+ }
#endif
return mdnid;
@@ -258,9 +263,12 @@ int ossl_digest_is_allowed(OSSL_LIB_CTX *ctx, const EVP_MD *md)
#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;
+ if (mdnid == NID_sha1 || mdnid == NID_md5_sha1) {
+ if (!ossl_ctx_legacy_digest_signatures_allowed(ctx, 0))
+ return 0;
+ else
+ DTRACE_PROBE1(libcrypto, fedora_ossl_digest_is_allowed_1, mdnid);
+ }
}
#endif
diff --git a/providers/common/securitycheck_default.c b/providers/common/securitycheck_default.c
index ce54a94fbc..2d21e4a7df 100644
--- a/providers/common/securitycheck_default.c
+++ b/providers/common/securitycheck_default.c
@@ -17,6 +17,8 @@
#include "internal/nelem.h"
#include "internal/sslconf.h"
+#include <sys/sdt.h>
+
/* Disable the security checks in the default provider */
int ossl_securitycheck_enabled(OSSL_LIB_CTX *libctx)
{
@@ -40,9 +42,16 @@ int ossl_digest_rsa_sign_get_md_nid(OSSL_LIB_CTX *ctx, const EVP_MD *md,
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_sha1)
+ /* This will only happen if SHA1 is allowed, otherwise mdnid is -1. */
+ DTRACE_PROBE1(libcrypto, fedora_ossl_digest_rsa_sign_get_md_nid_1, mdnid);
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;
+ if (mdnid == NID_md5_sha1) {
+ if (ldsigs_allowed)
+ DTRACE_PROBE1(libcrypto, fedora_ossl_digest_rsa_sign_get_md_nid_2, mdnid);
+ else
+ mdnid = -1;
+ }
return mdnid;
}
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 0b50266b69..d05e696a28 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -28,6 +28,8 @@
#include "ssl_local.h"
#include <openssl/ct.h>
+#include <sys/sdt.h>
+
static const SIGALG_LOOKUP *find_sig_alg(SSL *s, X509 *x, EVP_PKEY *pkey);
static int tls12_sigalg_allowed(const SSL *s, int op, const SIGALG_LOOKUP *lu);
@@ -1569,6 +1571,7 @@ int tls12_check_peer_sigalg(SSL *s, uint16_t sig, EVP_PKEY *pkey)
/* When rh-allow-sha1-signatures = yes and security level <= 1,
* explicitly allow SHA1 for backwards compatibility. Also allow
* MD5-SHA1 because TLS 1.0 is still supported, which uses it. */
+ DTRACE_PROBE1(libssl, fedora_tls12_check_peer_sigalg_1, lu->hash);
} else {
/*
* Make sure security callback allows algorithm. For historical
@@ -2122,6 +2125,7 @@ static int tls12_sigalg_allowed(const SSL *s, int op, const SIGALG_LOOKUP *lu)
/* When rh-allow-sha1-signatures = yes and security level <= 1,
* explicitly allow SHA1 for backwards compatibility. Also allow
* MD5-SHA1 because TLS 1.0 is still supported, which uses it. */
+ DTRACE_PROBE1(libssl, fedora_tls12_sigalg_allowed_1, lu->hash);
return 1;
}
@@ -3020,11 +3024,13 @@ static int ssl_security_cert_sig(SSL *s, SSL_CTX *ctx, X509 *x, int op)
&& ossl_ctx_legacy_digest_signatures_allowed(libctx, 0)
&& ((s != NULL && SSL_get_security_level(s) < 2)
|| (ctx != NULL && SSL_CTX_get_security_level(ctx) < 2)
- ))
+ )) {
/* When rh-allow-sha1-signatures = yes and security level <= 1,
* explicitly allow SHA1 for backwards compatibility. Also allow
* MD5-SHA1 because TLS 1.0 is still supported, which uses it. */
+ DTRACE_PROBE1(libssl, fedora_ssl_security_cert_sig_1, nid);
return 1;
+ }
if (s)
return ssl_security(s, op, secbits, nid, x);
--
2.35.1
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