Merge pull request #779 from paul-elliott-arm/discrepancy_cert_2_16
Backport 2.16: Add missing tag check to signature check on certificate load
diff --git a/ChangeLog.d/x509-add-tag-check-to-algorithm-params b/ChangeLog.d/x509-add-tag-check-to-algorithm-params
new file mode 100644
index 0000000..f2c72b0
--- /dev/null
+++ b/ChangeLog.d/x509-add-tag-check-to-algorithm-params
@@ -0,0 +1,11 @@
+Security
+ * Fix a compliance issue whereby we were not checking the tag on the
+ algorithm parameters (only the size) when comparing the signature in the
+ description part of the cert to the real signature. This meant that a
+ NULL algorithm parameters entry would look identical to an array of REAL
+ (size zero) to the library and thus the certificate would be considered
+ valid. However, if the parameters do not match in *any* way then the
+ certificate should be considered invalid, and indeed OpenSSL marks these
+ certs as invalid when mbedtls did not.
+ Many thanks to guidovranken who found this issue via differential fuzzing
+ and reported it in #3629.
diff --git a/library/x509_crt.c b/library/x509_crt.c
index d519a3f..fd89135 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1088,6 +1088,7 @@
if( crt->sig_oid.len != sig_oid2.len ||
memcmp( crt->sig_oid.p, sig_oid2.p, crt->sig_oid.len ) != 0 ||
+ sig_params1.tag != sig_params2.tag ||
sig_params1.len != sig_params2.len ||
( sig_params1.len != 0 &&
memcmp( sig_params1.p, sig_params2.p, sig_params1.len ) != 0 ) )
diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index 0429bdd..6c9e245 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -155,7 +155,11 @@
$(OPENSSL) x509 -in $< -out $@ -inform PEM -outform DER
all_final += cli-rsa-sha256.crt.der
- cli-rsa.key.der: $(cli_crt_key_file_rsa)
+cli-rsa-sha256-badalg.crt.der: cli-rsa-sha256.crt.der
+ hexdump -ve '1/1 "%.2X"' $< | sed "s/06092A864886F70D01010B0500/06092A864886F70D01010B0900/2" | xxd -r -p > $@
+all_final += cli-rsa-sha256-badalg.crt.der
+
+cli-rsa.key.der: $(cli_crt_key_file_rsa)
$(OPENSSL) pkey -in $< -out $@ -inform PEM -outform DER
all_final += cli-rsa.key.der
diff --git a/tests/data_files/cli-rsa-sha256-badalg.crt.der b/tests/data_files/cli-rsa-sha256-badalg.crt.der
new file mode 100644
index 0000000..c40ba2a
--- /dev/null
+++ b/tests/data_files/cli-rsa-sha256-badalg.crt.der
Binary files differ
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index 28ba79b..14ba0de 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -1876,6 +1876,10 @@
depends_on:MBEDTLS_ECDSA_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED:MBEDTLS_SHA256_C:MBEDTLS_RSA_C
x509parse_crt_file:"data_files/server7_trailing_space.crt":0
+X509 File parse (Algorithm Params Tag mismatch)
+depends_on:MBEDTLS_SHA256_C:MBEDTLS_RSA_C
+x509parse_crt_file:"data_files/cli-rsa-sha256-badalg.crt.der":MBEDTLS_ERR_X509_SIG_MISMATCH
+
X509 Get time (UTC no issues)
depends_on:MBEDTLS_X509_USE_C
x509_get_time:MBEDTLS_ASN1_UTC_TIME:"500101000000Z":0:1950:1:1:0:0:0