From f6a49b32fda99b726ad5b4434bcade613dccf49e Mon Sep 17 00:00:00 2001
From: tb <>
Date: Sun, 21 Dec 2025 07:14:47 +0000
Subject: Reimplement ASN1_PRINTABLE_type() dance in ca.c

In ca.c, there is some minimal validation of strings in the subject of
a certificate. ASN1_PRINTABLE_type() is silly API that only exists for
this one call. I want to remove a_print.c in the next major bump.

ASN1_PRINTABLE_type() returns V_ASN1_PRINTABLESTRING if all characters
belong to the specific subset of ASCII listed in X.680, 41.4, Table 10.
Otherwise it returns V_ASN1_T61STRING or V_ASN1_IA5STRING depending on
whether there is a character with the high bit set or not.

With this in mind, the logic in ca.c comes down to this: blindly allow
UTF-8, BMP and T61 strings. All other strings get rejected if the high
bit of some character is set, or if the string is printable and there
is a non-printable character.

ok jsing kenjiro
---
 src/usr.bin/openssl/ca.c | 68 +++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 55 insertions(+), 13 deletions(-)

(limited to 'src')

diff --git a/src/usr.bin/openssl/ca.c b/src/usr.bin/openssl/ca.c
index 525596ae7c..a2e8a68368 100644
--- a/src/usr.bin/openssl/ca.c
+++ b/src/usr.bin/openssl/ca.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ca.c,v 1.63 2025/11/27 08:24:30 tb Exp $ */
+/* $OpenBSD: ca.c,v 1.64 2025/12/21 07:14:47 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1652,6 +1652,54 @@ certify_cert(X509 **xret, char *infile, EVP_PKEY *pkey, X509 *x509,
 	return (ok);
 }
 
+static int
+is_printablestring_octet(const uint8_t u8)
+{
+	/*
+	 * X.680, 41.4, Table 10 lists the allowed characters in this order.
+	 */
+
+	if (u8 >= 'A' && u8 <= 'Z')
+		return 1;
+	if (u8 >= 'a' && u8 <= 'z')
+		return 1;
+	if (u8 >= '0' && u8 <= '9')
+		return 1;
+
+	return u8 == ' ' || u8 == '\'' || u8 == '(' || u8 == ')' || u8 == '+' ||
+	    u8 == ',' || u8 == '-' || u8 == '.' || u8 == '/' || u8 == ':' ||
+	    u8 == '=' || u8 == '?';
+}
+
+/*
+ * Allows the high bit to be set only for UTF8, BMP and T61 strings, and
+ * checks that a PrintableString only contains the specified characters.
+ */
+static int
+validate_octets(const ASN1_STRING *astr)
+{
+	const uint8_t *buf = ASN1_STRING_get0_data(astr);
+	int type = ASN1_STRING_type(astr);
+	int i;
+
+	if (type == V_ASN1_BMPSTRING || type == V_ASN1_UTF8STRING ||
+	    type == V_ASN1_T61STRING)
+		return 1;
+
+	for (i = 0; i < ASN1_STRING_length(astr); i++) {
+		if (is_printablestring_octet(buf[i]))
+			continue;
+
+		if (type == V_ASN1_PRINTABLESTRING)
+			return 0;
+
+		if ((buf[i] & 0x80) != 0)
+			return 0;
+	}
+
+	return 1;
+}
+
 static int
 do_body(X509 **xret, EVP_PKEY *pkey, X509 *x509, const EVP_MD *dgst,
     STACK_OF(OPENSSL_STRING) *sigopts, STACK_OF(CONF_VALUE) *policy,
@@ -1723,18 +1771,12 @@ do_body(X509 **xret, EVP_PKEY *pkey, X509 *x509, const EVP_MD *dgst,
 			    "\nemailAddress type needs to be of type IA5STRING\n");
 			goto err;
 		}
-		if ((ASN1_STRING_type(str) != V_ASN1_BMPSTRING) &&
-		    (ASN1_STRING_type(str) != V_ASN1_UTF8STRING)) {
-			j = ASN1_PRINTABLE_type(ASN1_STRING_get0_data(str),
-			    ASN1_STRING_length(str));
-			if (((j == V_ASN1_T61STRING) &&
-			    (ASN1_STRING_type(str) != V_ASN1_T61STRING)) ||
-			    ((j == V_ASN1_IA5STRING) &&
-			    (ASN1_STRING_type(str) == V_ASN1_PRINTABLESTRING))) {
-				BIO_printf(bio_err,
-				    "\nThe string contains characters that are illegal for the ASN.1 type\n");
-				goto err;
-			}
+
+		if (!validate_octets(str)) {
+			BIO_printf(bio_err,
+			    "\nThe string contains characters that are illegal "
+			    "for the ASN.1 type\n");
+			goto err;
 		}
 		if (default_op)
 			old_entry_print(bio_err, obj, str);
-- 
cgit v1.2.3-55-g6feb