test: add cert chain with mixed key sizes (#4433)

tests/pems/mixed_chains/README.md

@@ -0,0 +1,16 @@
+This folder contains "mixed key" cert chains.
+
+The `ecdsa` cert chain contains intermediate and leaf certs that are issued from a CA with a smaller key.
+```
+ leaf: P-384 key
+ ▲
+ │ signature: ECDSA with SHA384
+ │
+ intermediate: P-384 key
+ ▲
+ │ signature: ECDSA with SHA384
+ │
+ root: P-256 key
+ ▲
+   signature:ECDSA with SHA384
+```

tests/pems/mixed_chains/ecdsa/ca-cert.pem

@@ -0,0 +1,11 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

tests/pems/mixed_chains/ecdsa/server-chain.pem

@@ -0,0 +1,35 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

tests/pems/mixed_chains/ecdsa/server-key.pem

@@ -0,0 +1,6 @@
+-----BEGIN PRIVATE KEY-----
+MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDCosm1okl1Efmyz4wtv
+paXDecqqo/7P7l6AE1+357MBHB1us6CM677L66a6rS1YcRKhZANiAAQIl3I7/xUR
+YZY4mIYhQujKAv3W4me4QKnB0oinYiVzMpZ7/+I8YoeiOtzeuWER1TuoZ551mMTT
+SzPCfvgTwCyvbJdsWYIvcUD2afa/+z5mWhq0rYkvH0fOwTP7BiJh5bA=
+-----END PRIVATE KEY-----

tests/pems/mixed_chains/generate-certs.sh

@@ -0,0 +1,119 @@
+#!/usr/bin/env bash
+
+# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+# Usage: ./generate_certs.sh [clean]
+# Generates mixed-chain certs for testing
+# Use argument "clean" to remove all generated certs
+
+# immediately bail if any command fails
+set -e
+
+# Generates certs with given algorithms and bits in $1$2/, ex. ec384/
+# $1: rsa or ec
+# $2: size of the key used by the leaf and intermediate
+# $3: size of the key used by the issuing CA
+# $4: digest using in the certificate signatures
+# $5: name of the output directory
+cert-gen () {
+    key_family=$1
+    key_size=$2
+    ca_key_size=$3
+    digest=$4
+    dir_name=$5
+
+    echo -e "\n----- generating certs for ec $key_size with $digest $signature -----\n"
+
+    # make directory for certs
+    mkdir -p $dir_name
+    cd $dir_name
+
+    echo "generating CA private key and certificate"
+    openssl req -new -noenc -x509 \
+            -newkey ec \
+            -pkeyopt ec_paramgen_curve:P-$ca_key_size \
+            -keyout  ca-key.pem \
+            -out ca-cert.pem \
+            -days 65536 \
+            -$digest \
+            -subj "/C=US/CN=root" \
+            -addext "basicConstraints = critical,CA:true" \
+            -addext "keyUsage = critical,keyCertSign"
+
+    echo "generating intermediate private key and CSR"
+    openssl req  -new -noenc \
+            -newkey ec \
+            -pkeyopt ec_paramgen_curve:P-$key_size \
+            -keyout intermediate-key.pem \
+            -out intermediate.csr \
+            -subj "/C=US/CN=branch" \
+            -addext "basicConstraints = critical,CA:true" \
+            -addext "keyUsage = critical,keyCertSign"
+
+    echo "generating server private key and CSR"
+    openssl req  -new -noenc \
+            -newkey ec \
+            -pkeyopt ec_paramgen_curve:P-$key_size \
+            -keyout server-key.pem \
+            -out server.csr \
+            -subj "/C=US/CN=leaf" \
+            -addext "subjectAltName = DNS:localhost"
+
+    echo "generating intermediate certificate and signing it"
+    openssl x509 -days 65536 \
+            -req -in intermediate.csr \
+            -$digest \
+            -CA ca-cert.pem \
+            -CAkey ca-key.pem \
+            -CAcreateserial \
+            -out intermediate-cert.pem \
+            -copy_extensions=copyall
+
+    echo "generating server certificate and signing it"
+    openssl x509 -days 65536 \
+            -req -in server.csr \
+            -$digest \
+            -CA intermediate-cert.pem \
+            -CAkey intermediate-key.pem \
+            -CAcreateserial -out server-cert.pem \
+            -copy_extensions=copyall
+
+    touch server-chain.pem
+    cat server-cert.pem >> server-chain.pem
+    cat intermediate-cert.pem >> server-chain.pem
+    cat ca-cert.pem >> server-chain.pem
+
+    echo "verifying server certificates"
+    openssl verify -CAfile ca-cert.pem intermediate-cert.pem
+    openssl verify -CAfile ca-cert.pem -untrusted intermediate-cert.pem server-cert.pem
+
+    # certificate signing requests are never used after the certs are generated
+    rm server.csr
+    rm intermediate.csr
+
+    # serial files are generated during the signing process, but are not used
+    rm ca-cert.srl
+    rm intermediate-cert.srl
+
+    # the private keys of the CA and the intermediate CA are never needed after 
+    # signing
+    rm ca-key.pem
+    rm intermediate-key.pem
+
+    # the intermediate and server certs are included in server-chain.pem, so 
+    # the individual files can be deleted
+    rm intermediate-cert.pem
+    rm server-cert.pem
+
+    cd ..
+}
+
+if [[ $1 != "clean" ]]
+then
+    #         key   key_size  ca_key_size    digest     directory
+    cert-gen   ec     384        256         SHA384      ecdsa
+else
+    echo "cleaning certs"
+    rm -rf ecdsa*
+fi

tests/testlib/s2n_testlib.h

@@ -186,6 +186,11 @@ S2N_RESULT s2n_connection_set_test_master_secret(struct s2n_connection *conn, co
  * that our certificate validation code does not fail a root certificate signed with SHA-1. */
 #define S2N_SHA1_ROOT_SIGNATURE_CA_CERT "../pems/rsa_1024_sha1_CA_cert.pem"
 
+/* The leaf and intermediate have larger key sizes than the root. */
+#define S2N_MIXED_CHAIN_CERTS "../pems/mixed_chains/ecdsa/server-chain.pem"
+#define S2N_MIXED_CHAIN_KEY   "../pems/mixed_chains/ecdsa/server-key.pem"
+#define S2N_MIXED_CHAIN_CA    "../pems/mixed_chains/ecdsa/ca-cert.pem"
+
 #define S2N_DEFAULT_TEST_CERT_CHAIN  S2N_RSA_2048_PKCS1_CERT_CHAIN
 #define S2N_DEFAULT_TEST_PRIVATE_KEY S2N_RSA_2048_PKCS1_KEY