x509_vfy.c

开源项目openssl的源码

/* crypto/x509/x509_vfy.c */
/* Copyright (C) 1995-1998 Eric Young ([e-mail])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([e-mail]).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson ([e-mail]).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * 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 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 acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young ([e-mail])"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson ([e-mail])"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS 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 AUTHOR OR 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.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <time.h>
#include <errno.h>

#include "cryptlib.h"
#include <openssl/crypto.h>
#include <openssl/lhash.h>
#include <openssl/buffer.h>
#include <openssl/evp.h>
#include <openssl/asn1.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/objects.h>

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_trust(X509_STORE_CTX *ctx);
static int check_revocation(X509_STORE_CTX *ctx);
static int check_cert(X509_STORE_CTX *ctx);
static int internal_verify(X509_STORE_CTX *ctx);
const char *X509_version="X.509" OPENSSL_VERSION_PTEXT;


static int null_callback(int ok, X509_STORE_CTX *e)
	{
	return ok;
	}

#if 0
static int x509_subject_cmp(X509 **a, X509 **b)
	{
	return X509_subject_name_cmp(*a,*b);
	}
#endif

int X509_verify_cert(X509_STORE_CTX *ctx)
	{
	X509 *x,*xtmp,*chain_ss=NULL;
	X509_NAME *xn;
	int depth,i,ok=0;
	int num;
	int (*cb)();
	STACK_OF(X509) *sktmp=NULL;

	if (ctx->cert == NULL)
		{
		X509err(X509_F_X509_VERIFY_CERT,X509_R_NO_CERT_SET_FOR_US_TO_VERIFY);
		return -1;
		}

	cb=ctx->verify_cb;

	/* first we make sure the chain we are going to build is
	 * present and that the first entry is in place */
	if (ctx->chain == NULL)
		{
		if (	((ctx->chain=sk_X509_new_null()) == NULL) ||
			(!sk_X509_push(ctx->chain,ctx->cert)))
			{
			X509err(X509_F_X509_VERIFY_CERT,ERR_R_MALLOC_FAILURE);
			goto end;
			}
		CRYPTO_add(&ctx->cert->references,1,CRYPTO_LOCK_X509);
		ctx->last_untrusted=1;
		}

	/* We use a temporary STACK so we can chop and hack at it */
	if (ctx->untrusted != NULL
	    && (sktmp=sk_X509_dup(ctx->untrusted)) == NULL)
		{
		X509err(X509_F_X509_VERIFY_CERT,ERR_R_MALLOC_FAILURE);
		goto end;
		}

	num=sk_X509_num(ctx->chain);
	x=sk_X509_value(ctx->chain,num-1);
	depth=ctx->depth;


	for (;;)
		{
		/* If we have enough, we break */
		if (depth < num) break; /* FIXME: If this happens, we should take
		                         * note of it and, if appropriate, use the
		                         * X509_V_ERR_CERT_CHAIN_TOO_LONG error
		                         * code later.
		                         */

		/* If we are self signed, we break */
		xn=X509_get_issuer_name(x);
		if (ctx->check_issued(ctx, x,x)) break;

		/* If we were passed a cert chain, use it first */
		if (ctx->untrusted != NULL)
			{
			xtmp=find_issuer(ctx, sktmp,x);
			if (xtmp != NULL)
				{
				if (!sk_X509_push(ctx->chain,xtmp))
					{
					X509err(X509_F_X509_VERIFY_CERT,ERR_R_MALLOC_FAILURE);
					goto end;
					}
				CRYPTO_add(&xtmp->references,1,CRYPTO_LOCK_X509);
				sk_X509_delete_ptr(sktmp,xtmp);
				ctx->last_untrusted++;
				x=xtmp;
				num++;
				/* reparse the full chain for
				 * the next one */
				continue;
				}
			}
		break;
		}

	/* at this point, chain should contain a list of untrusted
	 * certificates.  We now need to add at least one trusted one,
	 * if possible, otherwise we complain. */

	/* Examine last certificate in chain and see if it
 	 * is self signed.
 	 */

	i=sk_X509_num(ctx->chain);
	x=sk_X509_value(ctx->chain,i-1);
	xn = X509_get_subject_name(x);
	if (ctx->check_issued(ctx, x, x))
		{
		/* we have a self signed certificate */
		if (sk_X509_num(ctx->chain) == 1)
			{
			/* We have a single self signed certificate: see if
			 * we can find it in the store. We must have an exact
			 * match to avoid possible impersonation.
			 */
			ok = ctx->get_issuer(&xtmp, ctx, x);
			if ((ok <= 0) || X509_cmp(x, xtmp)) 
				{
				ctx->error=X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT;
				ctx->current_cert=x;
				ctx->error_depth=i-1;
				if (ok == 1) X509_free(xtmp);
				ok=cb(0,ctx);
				if (!ok) goto end;
				}
			else 
				{
				/* We have a match: replace certificate with store version
				 * so we get any trust settings.
				 */
				X509_free(x);
				x = xtmp;
				sk_X509_set(ctx->chain, i - 1, x);
				ctx->last_untrusted=0;
				}
			}
		else
			{
			/* extract and save self signed certificate for later use */
			chain_ss=sk_X509_pop(ctx->chain);
			ctx->last_untrusted--;
			num--;
			x=sk_X509_value(ctx->chain,num-1);
			}
		}

	/* We now lookup certs from the certificate store */
	for (;;)
		{
		/* If we have enough, we break */
		if (depth < num) break;

		/* If we are self signed, we break */
		xn=X509_get_issuer_name(x);
		if (ctx->check_issued(ctx,x,x)) break;

		ok = ctx->get_issuer(&xtmp, ctx, x);

		if (ok < 0) return ok;
		if (ok == 0) break;

		x = xtmp;
		if (!sk_X509_push(ctx->chain,x))
			{
			X509_free(xtmp);
			X509err(X509_F_X509_VERIFY_CERT,ERR_R_MALLOC_FAILURE);
			return 0;
			}
		num++;
		}

	/* we now have our chain, lets check it... */
	xn=X509_get_issuer_name(x);

	/* Is last certificate looked up self signed? */
	if (!ctx->check_issued(ctx,x,x))
		{
		if ((chain_ss == NULL) || !ctx->check_issued(ctx, x, chain_ss))
			{
			if (ctx->last_untrusted >= num)
				ctx->error=X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY;
			else
				ctx->error=X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT;
			ctx->current_cert=x;
			}
		else
			{

			sk_X509_push(ctx->chain,chain_ss);
			num++;
			ctx->last_untrusted=num;
			ctx->current_cert=chain_ss;
			ctx->error=X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN;
			chain_ss=NULL;
			}

		ctx->error_depth=num-1;
		ok=cb(0,ctx);
		if (!ok) goto end;
		}

	/* We have the chain complete: now we need to check its purpose */
	if (ctx->purpose > 0) ok = check_chain_purpose(ctx);

	if (!ok) goto end;

	/* The chain extensions are OK: check trust */

	if (ctx->trust > 0) ok = check_trust(ctx);

	if (!ok) goto end;

	/* We may as well copy down any DSA parameters that are required */
	X509_get_pubkey_parameters(NULL,ctx->chain);

	/* Check revocation status: we do this after copying parameters
	 * because they may be needed for CRL signature verification.
	 */

	ok = ctx->check_revocation(ctx);
	if(!ok) goto end;

	/* At this point, we have a chain and just need to verify it */
	if (ctx->verify != NULL)
		ok=ctx->verify(ctx);
	else
		ok=internal_verify(ctx);
	if (0)
		{
end:
		X509_get_pubkey_parameters(NULL,ctx->chain);
		}
	if (sktmp != NULL) sk_X509_free(sktmp);
	if (chain_ss != NULL) X509_free(chain_ss);
	return ok;
	}


/* Given a STACK_OF(X509) find the issuer of cert (if any)
 */

static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x)
{
	int i;
	X509 *issuer;
	for (i = 0; i < sk_X509_num(sk); i++)
		{
		issuer = sk_X509_value(sk, i);
		if (ctx->check_issued(ctx, x, issuer))
			return issuer;
		}
	return NULL;
}

/* Given a possible certificate and issuer check them */

static int check_issued(X509_STORE_CTX *ctx, X509 *x, X509 *issuer)
{
	int ret;
	ret = X509_check_issued(issuer, x);
	if (ret == X509_V_OK)
		return 1;
	/* If we haven't asked for issuer errors don't set ctx */
	if (!(ctx->flags & X509_V_FLAG_CB_ISSUER_CHECK))
		return 0;

	ctx->error = ret;
	ctx->current_cert = x;
	ctx->current_issuer = issuer;
	return ctx->verify_cb(0, ctx);
	return 0;
}

/* Alternative lookup method: look from a STACK stored in other_ctx */

static int get_issuer_sk(X509 **issuer, X509_STORE_CTX *ctx, X509 *x)
{
	*issuer = find_issuer(ctx, ctx->other_ctx, x);
	if (*issuer)
		{
		CRYPTO_add(&(*issuer)->references,1,CRYPTO_LOCK_X509);
		return 1;
		}
	else
		return 0;
}
	

/* Check a certificate chains extensions for consistency
 * with the supplied purpose
 */

static int check_chain_purpose(X509_STORE_CTX *ctx)
{
#ifdef OPENSSL_NO_CHAIN_VERIFY
	return 1;
#else
	int i, ok=0;
	X509 *x;
	int (*cb)();
	cb=ctx->verify_cb;
	/* Check all untrusted certificates */
	for (i = 0; i < ctx->last_untrusted; i++)
		{
		int ret;
		x = sk_X509_value(ctx->chain, i);
		if (!(ctx->flags & X509_V_FLAG_IGNORE_CRITICAL)
			&& (x->ex_flags & EXFLAG_CRITICAL))
			{
			ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION;
			ctx->error_depth = i;
			ctx->current_cert = x;
			ok=cb(0,ctx);
			if (!ok) goto end;
			}
		ret = X509_check_purpose(x, ctx->purpose, i);
		if ((ret == 0)
			 || ((ctx->flags & X509_V_FLAG_X509_STRICT)
				&& (ret != 1)))
			{
			if (i)
				ctx->error = X509_V_ERR_INVALID_CA;
			else
				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)))
			{
			ctx->error = X509_V_ERR_PATH_LENGTH_EXCEEDED;
			ctx->error_depth = i;
			ctx->current_cert = x;
			ok=cb(0,ctx);
			if (!ok) goto end;
			}
		}
	ok = 1;
 end:
	return ok;
#endif
}

static int check_trust(X509_STORE_CTX *ctx)
{
#ifdef OPENSSL_NO_CHAIN_VERIFY
	return 1;
#else
	int i, ok;
	X509 *x;
	int (*cb)();
	cb=ctx->verify_cb;
/* For now just check the last certificate in the chain */
	i = sk_X509_num(ctx->chain) - 1;
	x = sk_X509_value(ctx->chain, i);
	ok = X509_check_trust(x, ctx->trust, 0);
	if (ok == X509_TRUST_TRUSTED)
		return 1;
	ctx->error_depth = i;
	ctx->current_cert = x;
	if (ok == X509_TRUST_REJECTED)
		ctx->error = X509_V_ERR_CERT_REJECTED;
	else
		ctx->error = X509_V_ERR_CERT_UNTRUSTED;
	ok = cb(0, ctx);
	return ok;
#endif
}

static int check_revocation(X509_STORE_CTX *ctx)
	{
	int i, last, ok;
	if (!(ctx->flags & X509_V_FLAG_CRL_CHECK))
		return 1;
	if (ctx->flags & X509_V_FLAG_CRL_CHECK_ALL)
		last = sk_X509_num(ctx->chain) - 1;
	else
		last = 0;
	for(i = 0; i <= last; i++)
		{
		ctx->error_depth = i;
		ok = check_cert(ctx);
		if (!ok) return ok;
		}
	return 1;
	}

static int check_cert(X509_STORE_CTX *ctx)
	{
	X509_CRL *crl = NULL;
	X509 *x;
	int ok, cnum;
	cnum = ctx->error_depth;
	x = sk_X509_value(ctx->chain, cnum);
	ctx->current_cert = x;
	/* Try to retrieve relevant CRL */
	ok = ctx->get_crl(ctx, &crl, x);
	/* If error looking up CRL, nothing we can do except
	 * notify callback
	 */
	if(!ok)
		{
		ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
		ok = ctx->verify_cb(0, ctx);
		goto err;
		}
	ctx->current_crl = crl;
	ok = ctx->check_crl(ctx, crl);
	if (!ok) goto err;
	ok = ctx->cert_crl(ctx, crl, x);
	err:
	ctx->current_crl = NULL;
	X509_CRL_free(crl);
	return ok;

	}

/* Retrieve CRL corresponding to certificate: currently just a
 * subject lookup: maybe use AKID later...
 * Also might look up any included CRLs too (e.g PKCS#7 signedData).
 */
static int get_crl(X509_STORE_CTX *ctx, X509_CRL **crl, X509 *x)
	{
	int ok;
	X509_OBJECT xobj;
	ok = X509_STORE_get_by_subject(ctx, X509_LU_CRL, X509_get_issuer_name(x), &xobj);
	if (!ok) return 0;
	*crl = xobj.data.crl;
	return 1;
	}

/* Check CRL validity */
static int check_crl(X509_STORE_CTX *ctx, X509_CRL *crl)
	{
	X509 *issuer = NULL;
	EVP_PKEY *ikey = NULL;
	int ok = 0, chnum, cnum, i;
	time_t *ptime;
	cnum = ctx->error_depth;
	chnum = sk_X509_num(ctx->chain) - 1;
	/* Find CRL issuer: if not last certificate then issuer
	 * is next certificate in chain.
	 */
	if(cnum < chnum)
		issuer = sk_X509_value(ctx->chain, cnum + 1);
	else
		{
		issuer = sk_X509_value(ctx->chain, chnum);
		/* If not self signed, can't check signature */
		if(!ctx->check_issued(ctx, issuer, issuer))
			{
			ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER;
			ok = ctx->verify_cb(0, ctx);
			if(!ok) goto err;
			}
		}

	if(issuer)
		{
		/* Check for cRLSign bit if keyUsage present */
		if ((issuer->ex_flags & EXFLAG_KUSAGE) &&
			!(issuer->ex_kusage & KU_CRL_SIGN))
			{
			ctx->error = X509_V_ERR_KEYUSAGE_NO_CRL_SIGN;
			ok = ctx->verify_cb(0, ctx);
			if(!ok) goto err;
			}

		/* Attempt to get issuer certificate public key */
		ikey = X509_get_pubkey(issuer);

		if(!ikey)
			{
			ctx->error=X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY;
			ok = ctx->verify_cb(0, ctx);
			if (!ok) goto err;
			}
		else
			{
			/* Verify CRL signature */
			if(X509_CRL_verify(crl, ikey) <= 0)
				{
				ctx->error=X509_V_ERR_CRL_SIGNATURE_FAILURE;
				ok = ctx->verify_cb(0, ctx);
				if (!ok) goto err;
				}
			}
		}

	/* OK, CRL signature valid check times */
	if (ctx->flags & X509_V_FLAG_USE_CHECK_TIME)
		ptime = &ctx->check_time;
	else
		ptime = NULL;

	i=X509_cmp_time(X509_CRL_get_lastUpdate(crl), ptime);
	if (i == 0)
		{
		ctx->error=X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD;
		ok = ctx->verify_cb(0, ctx);
		if (!ok) goto err;
		}

	if (i > 0)
		{
		ctx->error=X509_V_ERR_CRL_NOT_YET_VALID;
		ok = ctx->verify_cb(0, ctx);
		if (!ok) goto err;
		}

	if(X509_CRL_get_nextUpdate(crl))
		{
		i=X509_cmp_time(X509_CRL_get_nextUpdate(crl), ptime);

		if (i == 0)
			{
			ctx->error=X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD;
			ok = ctx->verify_cb(0, ctx);
			if (!ok) goto err;
			}

		if (i < 0)
			{
			ctx->error=X509_V_ERR_CRL_HAS_EXPIRED;
			ok = ctx->verify_cb(0, ctx);
			if (!ok) goto err;
			}
		}

	ok = 1;