Initial support for certificate purpose checking: this will

ultimately lead to certificate chain verification. It is
VERY EXPERIMENTAL at present though.

1 files changed, 366 insertions, 0 deletions

diff --git a/crypto/x509v3/v3_purp.c b/crypto/x509v3/v3_purp.c
new file mode 100644
index 0000000000..9c4706e715
--- /dev/null
+++ b/crypto/x509v3/v3_purp.c
@@ -0,0 +1,366 @@
+/* v3_purp.c */
+/* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
+ * project 1999.
+ */
+/* ====================================================================
+ * Copyright (c) 1999 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    licensing@OpenSSL.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ *
+ */
+
+#include <stdio.h>
+#include "cryptlib.h"
+#include <openssl/x509v3.h>
+
+
+static int x509_purpose_get_idx(int id);
+void x509v3_cache_extensions(X509 *x);
+
+static int ca_check(X509 *x);
+static int check_purpose_ssl_client(X509_PURPOSE *xp, X509 *x, int ca);
+static int check_purpose_ssl_server(X509_PURPOSE *xp, X509 *x, int ca);
+static int check_purpose_ns_ssl_server(X509_PURPOSE *xp, X509 *x, int ca);
+static int purpose_smime(X509 *x, int ca);
+static int check_purpose_smime_sign(X509_PURPOSE *xp, X509 *x, int ca);
+static int check_purpose_smime_encrypt(X509_PURPOSE *xp, X509 *x, int ca);
+static int check_purpose_crl_sign(X509_PURPOSE *xp, X509 *x, int ca);
+
+static int xp_cmp(X509_PURPOSE **a, X509_PURPOSE **b);
+
+static X509_PURPOSE xstandard[] = {
+{1, check_purpose_ssl_client, "SSL client", NULL},
+{2, check_purpose_ssl_server, "SSL server", NULL},
+{3, check_purpose_ns_ssl_server, "Netscape SSL server", NULL},
+{4, check_purpose_smime_sign, "S/MIME signing", NULL},
+{5, check_purpose_smime_encrypt, "S/MIME encryption", NULL},
+{6, check_purpose_crl_sign, "CRL signing", NULL},
+{-1, NULL, NULL, NULL}
+};
+
+IMPLEMENT_STACK_OF(X509_PURPOSE)
+
+static STACK_OF(X509_PURPOSE) *xptable;
+
+static int xp_cmp(X509_PURPOSE **a, X509_PURPOSE **b)
+{
+	return (*a)->purpose_id - (*b)->purpose_id;
+}
+
+int X509_check_purpose(X509 *x, int id, int ca)
+{
+	int idx;
+	X509_PURPOSE *pt;
+	if(!(x->ex_flags & EXFLAG_SET)) {
+		CRYPTO_w_lock(CRYPTO_LOCK_X509);
+		x509v3_cache_extensions(x);
+		CRYPTO_w_unlock(CRYPTO_LOCK_X509);
+	}
+	idx = x509_purpose_get_idx(id);
+	if(idx == -1) return -1;
+	pt = sk_X509_PURPOSE_value(xptable, idx);
+	return pt->check_purpose(pt, x,ca);
+}
+			
+	
+
+
+static int x509_purpose_get_idx(int id)
+{
+	X509_PURPOSE tmp;
+	tmp.purpose_id = id;
+	if(!xptable) return -1;
+	return sk_X509_PURPOSE_find(xptable, &tmp);
+}
+
+int X509_PURPOSE_add(X509_PURPOSE *xp)
+{
+	int idx;
+	if(!xptable) xptable = sk_X509_PURPOSE_new(xp_cmp);
+	idx = x509_purpose_get_idx(xp->purpose_id);
+	if(idx != -1) sk_X509_PURPOSE_set(xptable, idx, xp);
+	else sk_X509_PURPOSE_push(xptable, xp);
+	return 1;
+}
+
+void X509_PURPOSE_add_standard(void)
+{
+	X509_PURPOSE *xp;
+	for(xp = xstandard; xp->purpose_name; xp++)
+		X509_PURPOSE_add(xp);
+}
+
+int X509_PURPOSE_enum(int (*efunc)(X509_PURPOSE *, void *), void *usr)
+{
+	int i;
+	X509_PURPOSE *xp;
+	if(!xptable) return 0;
+	for(i = 0; i < sk_X509_PURPOSE_num(xptable); i++) {
+		xp = sk_X509_PURPOSE_value(xptable, i);
+		if(!efunc(xp, usr)) return i;
+	}
+	return i;
+}
+
+
+int X509_PURPOSE_get_id(X509_PURPOSE *xp)
+{
+	return xp->purpose_id;
+}
+
+char *X509_PURPOSE_get_name(X509_PURPOSE *xp)
+{
+	return xp->purpose_name;
+}
+
+void x509v3_cache_extensions(X509 *x)
+{
+	BASIC_CONSTRAINTS *bs;
+	ASN1_BIT_STRING *usage;
+	ASN1_BIT_STRING *ns;
+	STACK_OF(ASN1_OBJECT) *extusage;
+	int i;
+	if(x->ex_flags & EXFLAG_SET) return;
+	/* Does subject name match issuer ? */
+	if(X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
+			 x->ex_flags |= EXFLAG_SS;
+	/* V1 should mean no extensions ... */
+	if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
+	/* Handle basic constraints */
+	if((bs=X509V3_X509_get_d2i(x, NID_basic_constraints, NULL, NULL))) {
+		if(bs->ca) x->ex_flags |= EXFLAG_CA;
+		if(bs->pathlen) {
+			if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
+						|| !bs->ca) {
+				x->ex_flags |= EXFLAG_INVALID;
+				x->ex_pathlen = 0;
+			} else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
+		} else x->ex_pathlen = -1;
+		BASIC_CONSTRAINTS_free(bs);
+		x->ex_flags |= EXFLAG_BCONS;
+	}
+	/* Handle key usage */
+	if((usage=X509V3_X509_get_d2i(x, NID_key_usage, NULL, NULL))) {
+		if(usage->length > 0) {
+			x->ex_kusage = usage->data[0];
+			if(usage->length > 1) 
+				x->ex_kusage |= usage->data[1] << 8;
+		} else x->ex_kusage = 0;
+		x->ex_flags |= EXFLAG_KUSAGE;
+		ASN1_BIT_STRING_free(usage);
+	}
+	x->ex_xkusage = 0;
+	if((extusage=X509V3_X509_get_d2i(x, NID_ext_key_usage, NULL, NULL))) {
+		x->ex_flags |= EXFLAG_XKUSAGE;
+		for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
+			switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
+				case NID_server_auth:
+				x->ex_xkusage |= XKU_SSL_SERVER;
+				break;
+
+				case NID_client_auth:
+				x->ex_xkusage |= XKU_SSL_CLIENT;
+				break;
+
+				case NID_email_protect:
+				x->ex_xkusage |= XKU_SMIME;
+				break;
+
+				case NID_code_sign:
+				x->ex_xkusage |= XKU_CODE_SIGN;
+				break;
+
+				case NID_ms_sgc:
+				case NID_ns_sgc:
+				x->ex_xkusage |= XKU_SGC;
+			}
+		}
+		sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
+	}
+
+	if((ns=X509V3_X509_get_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
+		if(ns->length > 0) x->ex_nscert = ns->data[0];
+		else x->ex_nscert = 0;
+		x->ex_flags |= EXFLAG_NSCERT;
+		ASN1_BIT_STRING_free(ns);
+	}
+	x->ex_flags |= EXFLAG_SET;
+}
+
+/* CA checks common to all purposes
+ * return codes:
+ * 0 not a CA
+ * 1 is a CA
+ * 2 basicConstraints absent so "maybe" a CA
+ * 3 basicConstraints absent but self signed V1.
+ */
+
+#define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
+#define ku_reject(x, usage) \
+	(((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
+#define xku_reject(x, usage) \
+	(((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
+#define ns_reject(x, usage) \
+	(((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
+
+static int ca_check(X509 *x)
+{
+	/* keyUsage if present should allow cert signing */
+	if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
+	if(x->ex_flags & EXFLAG_BCONS) {
+		if(x->ex_flags & EXFLAG_CA) return 1;
+		/* If basicConstraints says not a CA then say so */
+		else return 0;
+	} else {
+		if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
+		else return 2;
+	}
+}
+
+
+static int check_purpose_ssl_client(X509_PURPOSE *xp, X509 *x, int ca)
+{
+	if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
+	if(ca) {
+		int ca_ret;
+		ca_ret = ca_check(x);
+		if(!ca_ret) return 0;
+		/* check nsCertType if present */
+		if(x->ex_flags & EXFLAG_NSCERT) {
+			if(x->ex_nscert & NS_SSL_CA) return ca_ret;
+			return 0;
+		}
+		if(ca_ret != 2) return ca_ret;
+		else return 0;
+	}
+	/* We need to do digital signatures with it */
+	if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
+	/* nsCertType if present should allow SSL client use */	
+	if(ns_reject(x, NS_SSL_CLIENT)) return 0;
+	return 1;
+}
+
+static int check_purpose_ssl_server(X509_PURPOSE *xp, X509 *x, int ca)
+{
+	if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
+	/* Otherwise same as SSL client for a CA */
+	if(ca) return check_purpose_ssl_client(xp, x, 1);
+
+	if(ns_reject(x, NS_SSL_SERVER)) return 0;
+	/* Now as for keyUsage: we'll at least need to sign OR encipher */
+	if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
+	
+	return 1;
+
+}
+
+static int check_purpose_ns_ssl_server(X509_PURPOSE *xp, X509 *x, int ca)
+{
+	int ret;
+	ret = check_purpose_ssl_server(xp, x, ca);
+	if(!ret || ca) return ret;
+	/* We need to encipher or Netscape complains */
+	if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
+	return ret;
+}
+
+/* common S/MIME checks */
+static int purpose_smime(X509 *x, int ca)
+{
+	if(xku_reject(x,XKU_SMIME)) return 0;
+	if(ca) {
+		int ca_ret;
+		ca_ret = ca_check(x);
+		if(!ca_ret) return 0;
+		/* check nsCertType if present */
+		if(x->ex_flags & EXFLAG_NSCERT) {
+			if(x->ex_nscert & NS_SMIME_CA) return ca_ret;
+			return 0;
+		}
+		if(ca_ret != 2) return ca_ret;
+		else return 0;
+	}
+	if(x->ex_flags & EXFLAG_NSCERT) {
+		if(x->ex_nscert & NS_SMIME) return 1;
+		/* Workaround for some buggy certificates */
+		if(x->ex_nscert & NS_SSL_CLIENT) return 2;
+		return 0;
+	}
+	return 1;
+}
+
+static int check_purpose_smime_sign(X509_PURPOSE *xp, X509 *x, int ca)
+{
+	int ret;
+	ret = purpose_smime(x, ca);
+	if(!ret || ca) return ret;
+	if(ku_reject(x, KU_DIGITAL_SIGNATURE)) return 0;
+	return ret;
+}
+
+static int check_purpose_smime_encrypt(X509_PURPOSE *xp, X509 *x, int ca)
+{
+	int ret;
+	ret = purpose_smime(x, ca);
+	if(!ret || ca) return ret;
+	if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
+	return ret;
+}
+
+static int check_purpose_crl_sign(X509_PURPOSE *xp, X509 *x, int ca)
+{
+	if(ca) {
+		int ca_ret;
+		if((ca_ret = ca_check(x)) != 2) return ca_ret;
+		else return 0;
+	}
+	if(ku_reject(x, KU_CRL_SIGN)) return 0;
+	return 1;
+}