From: Elly Jones <ellyjones@chromium.org>
Subject: [PATCH] add blacklist-by-sha1 support

We can add certs to the blacklist by serial (with 'serial <n>') or by sha256sum
with ('sha256 <n>').

BUG=chromium:203154
TEST=script (added to package tests),security_OpenSSLBlacklist
TEST=`FEATURES=test emerge openssl`

--- a/crypto/x509/x509_vfy.c
+++ b/crypto/x509/x509_vfy.c
@@ -150,6 +150,125 @@
     return xtmp;
 }
 
+/* A version of fgets() that returns the first sz - 1 characters of the next
+ * line from 'in'. The rest of the line is discarded. */
+static int gets_trunc(BIO *in, char *buf, int sz)
+{
+	char b;
+	int i = 0;
+
+	if (sz < 1)
+		return i;
+
+	while (BIO_read(in, &b, 1)) {
+		if (i < sz - 1)
+			buf[i++] = b;
+		if (!b || b == '\n')
+			break;
+	}
+
+	buf[i] = '\0';
+
+	return i;
+}
+
+/* Converts a byte string into a hex string, null-terminated. The 'out' buffer
+ * must be at least 2 * insize + 1 bytes long. */
+static void hexify(unsigned char *in, char *out, int insize)
+{
+	int i;
+	static const char hex[] = "0123456789abcdef";
+	for (i = 0; i < insize; i++) {
+		out[i * 2] = hex[in[i] >> 4];
+		out[i * 2 + 1] = hex[in[i] & 0xf];
+	}
+	out[i * 2] = '\0';
+}
+
+static int is_blacklisted(X509 *x)
+{
+	/* See http://tools.ietf.org/html/rfc5280#section-4.1.2.2:
+	 * "Certificate users MUST be able to handle serialNumber values up to
+	 *  20 octets.  Conforming CAs MUST NOT use serialNumber values longer
+	 *  than 20 octets."
+	 */
+	static const int MAX_SERIAL = 20;
+	static const int MAX_BLACKLIST_LINE = 1024;
+
+	unsigned char md[EVP_MAX_MD_SIZE];
+	char hexsha256[EVP_MAX_MD_SIZE * 2 + 1];
+	char hexsha1[EVP_MAX_MD_SIZE * 2 + 1];
+	char hexserial[MAX_SERIAL * 2 + 1];
+	const EVP_MD *sha256 = EVP_sha256();
+	const EVP_MD *sha1 = EVP_sha1();
+	unsigned int n;
+	char line[MAX_BLACKLIST_LINE];
+	BIO *file;
+	int ret = 0;
+	ASN1_INTEGER *serial = NULL;
+	unsigned int serial_len;
+	const char *path = getenv("OPENSSL_BLACKLIST_PATH");
+
+	if (!path)
+		path = OPENSSLDIR "/blacklist";
+
+	file = BIO_new_file(path, "r");
+	if (!file)
+		return 0;
+
+	if (!X509_digest(x, sha256, md, &n))
+		goto out;
+	hexify(md, hexsha256, n);
+	if (!X509_digest(x, sha1, md, &n))
+		goto out;
+	hexify(md, hexsha1, n);
+	serial = X509_get_serialNumber(x);
+	serial_len = serial->length;
+	if (serial_len > sizeof(hexserial) / 2)
+		/* We only match the first MAX_SERIAL bytes of the serial. */
+		serial_len = sizeof(hexserial) / 2;
+	hexify(serial->data, hexserial, serial_len);
+
+	while (gets_trunc(file, line, sizeof(line))) {
+		char *p, *str = line;
+		char *cmd = strsep(&str, " ");
+		char *arg = strsep(&str, " ");
+		if (!cmd || !arg || cmd[0] == '#')
+			continue;
+		if ((p = strchr(arg, '\n')))
+			*p = '\0';
+		if (!strcmp(cmd, "sha256") && !strcmp(arg, hexsha256)) {
+			ret = 1;
+			goto out;
+		}
+		if (!strcmp(cmd, "sha1") && !strcmp(arg, hexsha1)) {
+			ret = 1;
+			goto out;
+		}
+		if (!strcmp(cmd, "serial") && !strcmp(arg, hexserial)) {
+			ret = 1;
+			goto out;
+		}
+	}
+
+out:
+	BIO_free(file);
+	return ret;
+}
+
+static int check_blacklist(X509_STORE_CTX *ctx)
+{
+	int i;
+	X509 *x;
+
+	for (i = 0; i < ctx->last_untrusted; i++) {
+		x = sk_X509_value(ctx->chain, i);
+		if (is_blacklisted(x))
+			return 0;
+	}
+	return 1;
+}
+
 int X509_verify_cert(X509_STORE_CTX *ctx)
 {
     X509 *x, *xtmp, *xtmp2, *chain_ss = NULL;
@@ -307,6 +426,14 @@ int X509_verify_cert(X509_STORE_CTX *ctx)
         }
 
         /* we now have our chain, lets check it... */
+
+	ok = check_blacklist(ctx);
+	if (!ok) {
+		ctx->error = X509_V_ERR_CERT_REJECTED;
+		ok = -1;
+		goto err;
+	}
+
         if ((trust = check_trust(ctx)) == X509_TRUST_REJECTED) {
             /* Callback already issued */
             ok = 0;
--- a/test/Makefile
+++ b/test/Makefile
@@ -218,6 +218,10 @@
 	@sh ./treq 2>/dev/null
 	@sh ./treq testreq2.pem 2>/dev/null
 
+alltests: test_blacklist
+test_blacklist:
+	@sh ./tblacklist
+
 test_pkcs7: ../apps/openssl$(EXE_EXT) tpkcs7 tpkcs7d testp7.pem pkcs7-1.pem
 	@sh ./tpkcs7 2>/dev/null
 	@sh ./tpkcs7d 2>/dev/null
--- /dev/null
+++ b/test/tblacklist
@@ -0,0 +1,75 @@
+#!/bin/sh
+# Test /etc/ssl/blacklist
+
+td=$(mktemp -d "openssl-test.XXXXXXXX")
+
+cat >> "$td/thawte.pem" << EOF
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+EOF
+
+cat >> "$td/google.pem" << EOF
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+EOF
+
+# These are from 'openssl x509 -in google.pem -text -fingerprint -sha256'
+google_sha256='f641c36cfef49bc071359ecf88eed9317b738b5989416ad401720c0a4e2e6352'
+google_sha1='405062e5befde4af97e9382af16cc87c8fb7c4e2'
+google_serial='2fdfbcf6ae91526d0f9aa3df40343e9a'
+blacklist="$td/blacklist"
+export OPENSSL_BLACKLIST_PATH="$blacklist"
+
+die () {
+	echo "$@"
+	exit 1
+}
+
+verify () {
+	openssl verify -CAfile "$td/thawte.pem" "$td/google.pem" > "$td/$1.out" 2> "$td/$1.err"
+}
+
+# First, ensure that the cert verifies with no changes.
+verify good || die "failed to verify good signature"
+echo "serial $google_serial" > "$blacklist"
+verify serial && die "verified with blacklisted serial"
+echo "sha256 $google_sha256" > "$blacklist"
+verify sha256 && die "verified with blacklisted sha256"
+echo "sha1 $google_sha1" > "$blacklist"
+verify sha1 && die "verified with blacklisted sha1"
+rm -rf "$td"
+exit 0