Make an explicit check during certificate validation to see that the

CA setting in each certificate on the chain is correct.  As a side-
effect always do the following basic checks on extensions, not just
when there's an associated purpose to the check:
- if there is an unhandled critical extension (unless the user has
  chosen to ignore this fault)
- if the path length has been exceeded (if one is set at all)
- that certain extensions fit the associated purpose (if one has been
  given)

2 files changed, 24 insertions, 27 deletions

diff --git a/crypto/x509v3/v3_purp.c b/crypto/x509v3/v3_purp.c
index 67596862ab..d37e79481a 100644
--- a/crypto/x509v3/v3_purp.c
+++ b/crypto/x509v3/v3_purp.c
@@ -63,7 +63,6 @@
 
 static void x509v3_cache_extensions(X509 *x);
 
-static int ca_check(const X509 *x);
 static int check_ssl_ca(const X509 *x);
 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca);
 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
@@ -426,8 +425,14 @@ static void x509v3_cache_extensions(X509 *x)
 #define ns_reject(x, usage) \
 	(((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
 
-static int ca_check(const X509 *x)
+int X509_check_ca(X509 *x)
 {
+	if(!(x->ex_flags & EXFLAG_SET)) {
+		CRYPTO_w_lock(CRYPTO_LOCK_X509);
+		x509v3_cache_extensions(x);
+		CRYPTO_w_unlock(CRYPTO_LOCK_X509);
+	}
+
 	/* keyUsage if present should allow cert signing */
 	if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
 	if(x->ex_flags & EXFLAG_BCONS) {
@@ -435,10 +440,17 @@ static int ca_check(const X509 *x)
 		/* If basicConstraints says not a CA then say so */
 		else return 0;
 	} else {
+		/* we support V1 roots for...  uh, I don't really know why. */
 		if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
 		/* If key usage present it must have certSign so tolerate it */
 		else if (x->ex_flags & EXFLAG_KUSAGE) return 4;
-		else return 2;
+		/* Older certificates could have Netscape-specific CA types */
+		else if (x->ex_flags & EXFLAG_NSCERT
+			 && x->ex_nscert & NS_ANY_CA) return 5;
+		/* 2 means "I don't know...", which is legal for V1 and V2 */
+		else if (x->ex_flags & EXFLAG_V1) return 2;
+		/* can this still be regarded a CA certificate?  I doubt it */
+		return 0;
 	}
 }
 
@@ -446,14 +458,10 @@ static int ca_check(const X509 *x)
 static int check_ssl_ca(const X509 *x)
 {
 	int ca_ret;
-	ca_ret = ca_check(x);
+	ca_ret = X509_check_ca(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;
+	if(ca_ret != 5 || x->ex_nscert & NS_SSL_CA) return ca_ret;
 	else return 0;
 }
 
@@ -498,14 +506,10 @@ static int purpose_smime(const X509 *x, int ca)
 	if(xku_reject(x,XKU_SMIME)) return 0;
 	if(ca) {
 		int ca_ret;
-		ca_ret = ca_check(x);
+		ca_ret = X509_check_ca(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;
+		if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
 		else return 0;
 	}
 	if(x->ex_flags & EXFLAG_NSCERT) {
@@ -539,7 +543,7 @@ static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 {
 	if(ca) {
 		int ca_ret;
-		if((ca_ret = ca_check(x)) != 2) return ca_ret;
+		if((ca_ret = X509_check_ca(x)) != 2) return ca_ret;
 		else return 0;
 	}
 	if(ku_reject(x, KU_CRL_SIGN)) return 0;
@@ -552,17 +556,9 @@ static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
 
 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 {
-	/* Must be a valid CA */
-	if(ca) {
-		int ca_ret;
-		ca_ret = ca_check(x);
-		if(ca_ret != 2) return ca_ret;
-		if(x->ex_flags & EXFLAG_NSCERT) {
-			if(x->ex_nscert & NS_ANY_CA) return ca_ret;
-			return 0;
-		}
-		return 0;
-	}
+	/* Must be a valid CA.  Should we really support the "I don't know"
+	   value (2)? */
+	if(ca) return X509_check_ca(x);
 	/* leaf certificate is checked in OCSP_verify() */
 	return 1;
 }
diff --git a/crypto/x509v3/x509v3.h b/crypto/x509v3/x509v3.h
index 677a930f77..a6436289c0 100644
--- a/crypto/x509v3/x509v3.h
+++ b/crypto/x509v3/x509v3.h
@@ -578,6 +578,7 @@ int X509V3_EXT_print_fp(FILE *out, X509_EXTENSION *ext, int flag, int indent);
 
 int X509V3_extensions_print(BIO *out, char *title, STACK_OF(X509_EXTENSION) *exts, unsigned long flag, int indent);
 
+int X509_check_ca(X509 *x);
 int X509_check_purpose(X509 *x, int id, int ca);
 int X509_supported_extension(X509_EXTENSION *ex);
 int X509_PURPOSE_set(int *p, int purpose);