Commit 30b415b0 authored by Richard Levitte's avatar Richard Levitte
Browse files

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)
parent 914c2a28

apps/verify.c

+1 −0
Original line number Diff line number Diff line
@@ -348,6 +348,7 @@ static int MS_CALLBACK cb(int ok, X509_STORE_CTX *ctx) 
		if (ctx->error == X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT) ok=1;

		/* Continue after extension errors too */

		if (ctx->error == X509_V_ERR_INVALID_CA) ok=1;

		if (ctx->error == X509_V_ERR_INVALID_NON_CA) ok=1;

		if (ctx->error == X509_V_ERR_PATH_LENGTH_EXCEEDED) ok=1;

		if (ctx->error == X509_V_ERR_INVALID_PURPOSE) ok=1;

		if (ctx->error == X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT) ok=1;

crypto/x509/x509_txt.c

+2 −0
Original line number Diff line number Diff line
@@ -122,6 +122,8 @@ const char *X509_verify_cert_error_string(long n) 
		return("certificate revoked");

	case X509_V_ERR_INVALID_CA:

		return ("invalid CA certificate");

	case X509_V_ERR_INVALID_NON_CA:

		return ("invalid non-CA certificate (has CA markings)");

	case X509_V_ERR_PATH_LENGTH_EXCEEDED:

		return ("path length constraint exceeded");

	case X509_V_ERR_INVALID_PURPOSE:

crypto/x509/x509_vfy.c

+64 −10
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ 
static int null_callback(int ok,X509_STORE_CTX *e);

static int check_issued(X509_STORE_CTX *ctx, X509 *x, X509 *issuer);

static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x);

static int check_chain_purpose(X509_STORE_CTX *ctx);

static int check_chain_extensions(X509_STORE_CTX *ctx);

static int check_trust(X509_STORE_CTX *ctx);

static int check_revocation(X509_STORE_CTX *ctx);

static int check_cert(X509_STORE_CTX *ctx);
@@ -285,7 +285,7 @@ int X509_verify_cert(X509_STORE_CTX *ctx) 
		}



	/* We have the chain complete: now we need to check its purpose */

	if (param->purpose > 0) ok = check_chain_purpose(ctx);

	ok = check_chain_extensions(ctx);



	if (!ok) goto end;
@@ -381,15 +381,25 @@ static int get_issuer_sk(X509 **issuer, X509_STORE_CTX *ctx, X509 *x) 
 * with the supplied purpose

 */



static int check_chain_purpose(X509_STORE_CTX *ctx)

static int check_chain_extensions(X509_STORE_CTX *ctx)

{

#ifdef OPENSSL_NO_CHAIN_VERIFY

	return 1;

#else

	int i, ok=0;

	int i, ok=0, must_be_ca;

	X509 *x;

	int (*cb)();

	cb=ctx->verify_cb;



	/* must_be_ca can have 1 of 3 values:

	   -1: we accept both CA and non-CA certificates, to allow direct

	       use of self-signed certificates (which are marked as CA).

	   0:  we only accept non-CA certificates.  This is currently not

	       used, but the possibility is present for future extensions.

	   1:  we only accept CA certificates.  This is currently used for

	       all certificates in the chain except the leaf certificate.

	*/

	must_be_ca = -1;

	/* Check all untrusted certificates */

	for (i = 0; i < ctx->last_untrusted; i++)

		{
@@ -404,20 +414,62 @@ static int check_chain_purpose(X509_STORE_CTX *ctx) 
			ok=cb(0,ctx);

			if (!ok) goto end;

			}

		ret = X509_check_purpose(x, ctx->param->purpose, i);

		ret = X509_check_ca(x);

		switch(must_be_ca)

			{

		case -1:

			if ((ctx->param->flags & X509_V_FLAG_X509_STRICT)

				&& (ret != 1) && (ret != 0))

				{

				ret = 0;

				ctx->error = X509_V_ERR_INVALID_CA;

				}

			else

				ret = 1;

			break;

		case 0:

			if (ret != 0)

				{

				ret = 0;

				ctx->error = X509_V_ERR_INVALID_NON_CA;

				}

			else

				ret = 1;

			break;

		default:

			if ((ret == 0)

				|| ((ctx->param->flags & X509_V_FLAG_X509_STRICT)

					&& (ret != 1)))

				{

			if (i)

				ret = 0;

				ctx->error = X509_V_ERR_INVALID_CA;

				}

			else

				ret = 1;

			break;

			}

		if (ret == 0)

			{

			ctx->error_depth = i;

			ctx->current_cert = x;

			ok=cb(0,ctx);

			if (!ok) goto end;

			}

		if (ctx->param->purpose > 0)

			{

			ret = X509_check_purpose(x, ctx->param->purpose,

				must_be_ca > 0);

			if ((ret == 0)

				|| ((ctx->param->flags & X509_V_FLAG_X509_STRICT)

					&& (ret != 1)))

				{

				ctx->error = X509_V_ERR_INVALID_PURPOSE;

				ctx->error_depth = i;

				ctx->current_cert = x;

				ok=cb(0,ctx);

				if (!ok) goto end;

				}

			}

		/* Check pathlen */

		if ((i > 1) && (x->ex_pathlen != -1)

			   && (i > (x->ex_pathlen + 1)))
@@ -428,6 +480,8 @@ static int check_chain_purpose(X509_STORE_CTX *ctx) 
			ok=cb(0,ctx);

			if (!ok) goto end;

			}

		/* The next certificate must be a CA */

		must_be_ca = 1;

		}

	ok = 1;

 end:

crypto/x509/x509_vfy.h

+4 −3
Original line number Diff line number Diff line
@@ -322,10 +322,11 @@ void X509_STORE_CTX_set_depth(X509_STORE_CTX *ctx, int depth); 
#define		X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION		34

#define		X509_V_ERR_KEYUSAGE_NO_CRL_SIGN			35

#define		X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION	36

#define		X509_V_ERR_INVALID_NON_CA			37



#define		X509_V_ERR_INVALID_EXTENSION			37

#define		X509_V_ERR_INVALID_POLICY_EXTENSION		38

#define		X509_V_ERR_NO_EXPLICIT_POLICY			39

#define		X509_V_ERR_INVALID_EXTENSION			38

#define		X509_V_ERR_INVALID_POLICY_EXTENSION		39

#define		X509_V_ERR_NO_EXPLICIT_POLICY			40





/* The application is not happy */

crypto/x509v3/v3_purp.c

+23 −27
Original line number Diff line number Diff line
@@ -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;

}