Always revoke certificate on CRL

RFC5280 does not state that the `revocationDate` should be checked. In addition, when no time source is available (i.e., when MBEDTLS_HAVE_TIME_DATE is not defined), `mbedtls_x509_time_is_past` always returns 0. This results in the CRL not being checked at all. https://tools.ietf.org/html/rfc5280 Signed-off-by: Raoul Strackx <[email protected]>
Mbed-TLS · Jun 26, 2020 · b21e509 · b21e509
1 parent b21b1f5
commit b21e509
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Showing 7 changed files with 46 additions and 4 deletions.
diff --git a/ChangeLog.d/crl-revocationDate.txt b/ChangeLog.d/crl-revocationDate.txt
@@ -0,0 +1,10 @@
+Security
+   * When checking X.509 CRLs, a certificate was only considered as revoked if
+     its revocationDate was in the past according to the local clock if
+     available. In particular, on builds without MBEDTLS_HAVE_TIME_DATE,
+     certificates were never considered as revoked. On builds with
+     MBEDTLS_HAVE_TIME_DATE, an attacker able to control the local clock (for
+     example, an untrusted OS attacking a secure enclave) could prevent
+     revocation of certificates via CRLs. Fixed by no longer checking the
+     revocationDate field, in accordance with RFC 5280.  Reported and fixed by
+     Raoul Strackx & Jethro Beekman.
diff --git a/library/x509_crt.c b/library/x509_crt.c
@@ -2320,8 +2320,7 @@ int mbedtls_x509_crt_is_revoked( const mbedtls_x509_crt *crt, const mbedtls_x509
         if( crt->serial.len == cur->serial.len &&
             memcmp( crt->serial.p, cur->serial.p, crt->serial.len ) == 0 )
         {
-            if( mbedtls_x509_time_is_past( &cur->revocation_date ) )
-                return( 1 );
+            return( 1 );
         }
 
         cur = cur->next;

diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
@@ -1054,7 +1054,10 @@ server1.v1.der.openssl: server1.v1.crt.openssl
 crl.pem: $(test_ca_crt) $(test_ca_key_file_rsa) $(test_ca_config_file)
 	$(OPENSSL) ca -gencrl -batch -cert $(test_ca_crt) -keyfile $(test_ca_key_file_rsa) -key $(test_ca_pwd_rsa) -config $(test_ca_server1_config_file) -md sha1 -crldays 3653 -out $@
 
-server1_all: crl.pem server1.crt server1.noauthid.crt server1.crt.openssl server1.v1.crt server1.v1.crt.openssl server1.key_usage.crt server1.key_usage_noauthid.crt server1.key_usage.crt.openssl server1.cert_type.crt server1.cert_type_noauthid.crt server1.cert_type.crt.openssl server1.der server1.der.openssl server1.v1.der server1.v1.der.openssl server1.key_usage.der server1.key_usage.der.openssl server1.cert_type.der server1.cert_type.der.openssl
+crl-futureRevocationDate.pem: $(test_ca_crt) $(test_ca_key_file_rsa) $(test_ca_config_file)
+	$(FAKETIME) '3000-01-01' $(OPENSSL) ca -gencrl -batch -cert $(test_ca_crt) -keyfile $(test_ca_key_file_rsa) -key $(test_ca_pwd_rsa) -config $(test_ca_server1_config_file) -md sha1 -crldays 3653 -out $@
+
+server1_all: crl.pem crl-futureRevocationDate.pem server1.crt server1.noauthid.crt server1.crt.openssl server1.v1.crt server1.v1.crt.openssl server1.key_usage.crt server1.key_usage_noauthid.crt server1.key_usage.crt.openssl server1.cert_type.crt server1.cert_type_noauthid.crt server1.cert_type.crt.openssl server1.der server1.der.openssl server1.v1.der server1.v1.der.openssl server1.key_usage.der server1.key_usage.der.openssl server1.cert_type.der server1.cert_type.der.openssl
 
 # server2*
 

diff --git a/tests/data_files/Readme-x509.txt b/tests/data_files/Readme-x509.txt
@@ -111,7 +111,7 @@ Signing CA in parentheses (same meaning as certificates).
 - crl-ec-sha*.pem: (2) server6.crt
 - crl-future.pem: (2) server6.crt + unknown
 - crl-rsa-pss-*.pem: (1) server9{,badsign,with-ca}.crt + cert_sha384.crt + unknown
-- crl.pem, crl_expired.pem: (1) server1{,.cert_type,.key_usage,.v1}.crt + unknown
+- crl.pem, crl-futureRevocationDate.pem, crl_expired.pem: (1) server1{,.cert_type,.key_usage,.v1}.crt + unknown
 - crl_md*.pem: crl_sha*.pem: (1) same as crl.pem
 - crt_cat_*.pem: (1+2) concatenations in various orders:
     ec = crl-ec-sha256.pem, ecfut = crl-future.pem

diff --git a/tests/data_files/crl-futureRevocationDate.pem b/tests/data_files/crl-futureRevocationDate.pem
@@ -0,0 +1,12 @@
+-----BEGIN X509 CRL-----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+-----END X509 CRL-----
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
@@ -1380,6 +1380,16 @@ component_test_null_entropy () {
     make test
 }
 
+component_test_no_date_time () {
+    msg "build: default config without MBEDTLS_HAVE_TIME_DATE"
+    scripts/config.py unset MBEDTLS_HAVE_TIME_DATE
+    CC=gcc cmake
+    make
+
+    msg "test: !MBEDTLS_HAVE_TIME_DATE - main suites"
+    make test
+}
+
 component_test_platform_calloc_macro () {
     msg "build: MBEDTLS_PLATFORM_{CALLOC/FREE}_MACRO enabled (ASan build)"
     scripts/config.py set MBEDTLS_PLATFORM_MEMORY

diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
@@ -911,6 +911,14 @@ X509 CRT verification #97 (next profile Valid Cert SHA256 Digest)
 depends_on:MBEDTLS_SHA256_C:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_ECDSA_C:MBEDTLS_SHA1_C
 x509_verify:"data_files/cert_sha256.crt":"data_files/test-ca.crt":"data_files/crl-ec-sha256.pem":"NULL":0:0:"next":"NULL"
 
+X509 CRT verification #98 (Revoked Cert, revocation date in the future, _with_ MBEDTLS_HAVE_TIME_DATE)
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_HAVE_TIME_DATE
+x509_verify:"data_files/server1.crt":"data_files/test-ca.crt":"data_files/crl-futureRevocationDate.pem":"NULL":MBEDTLS_ERR_X509_CERT_VERIFY_FAILED:MBEDTLS_X509_BADCERT_REVOKED|MBEDTLS_X509_BADCRL_FUTURE:"compat":"NULL"
+
+X509 CRT verification #99 (Revoked Cert, revocation date in the future, _without_ MBEDTLS_HAVE_TIME_DATE)
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:!MBEDTLS_HAVE_TIME_DATE
+x509_verify:"data_files/server1.crt":"data_files/test-ca.crt":"data_files/crl-futureRevocationDate.pem":"NULL":MBEDTLS_ERR_X509_CERT_VERIFY_FAILED:MBEDTLS_X509_BADCERT_REVOKED:"compat":"NULL"
+
 X509 CRT verification with ca callback: failure
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 x509_verify_ca_cb_failure:"data_files/server1.crt":"data_files/test-ca.crt":"NULL":MBEDTLS_ERR_X509_FATAL_ERROR