Fix various certificate fingerprint issues.

By using non-DER or invalid encodings outside the signed portion of a
certificate the fingerprint can be changed without breaking the signature.
Although no details of the signed portion of the certificate can be changed
this can cause problems with some applications: e.g. those using the
certificate fingerprint for blacklists.

1. Reject signatures with non zero unused bits.

If the BIT STRING containing the signature has non zero unused bits reject
the signature. All current signature algorithms require zero unused bits.

2. Check certificate algorithm consistency.

Check the AlgorithmIdentifier inside TBS matches the one in the
certificate signature. NB: this will result in signature failure
errors for some broken certificates.

3. Check DSA/ECDSA signatures use DER.

Reencode DSA/ECDSA signatures and compare with the original received
signature. Return an error if there is a mismatch.

This will reject various cases including garbage after signature
(thanks to Antti Karjalainen and Tuomo Untinen from the Codenomicon CROSS
program for discovering this case) and use of BER or invalid ASN.1 INTEGERs
(negative or with leading zeroes).

CVE-2014-8275
Reviewed-by: Emilia Käsper <emilia@openssl.org>

(cherry picked from commit 208a6012be3077d83df4475f32dd1b1446f3a02e)

Conflicts:
	crypto/dsa/dsa_vrf.c

5 files changed, 78 insertions, 4 deletions

diff --git a/CHANGES b/CHANGES
index d236eea832..60a45965d3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,7 +4,42 @@
 
  Changes between 0.9.8zc and 0.9.8zd [xx XXX xxxx]
 
-  *)
+  *) Fix various certificate fingerprint issues.
+
+     By using non-DER or invalid encodings outside the signed portion of a
+     certificate the fingerprint can be changed without breaking the signature.
+     Although no details of the signed portion of the certificate can be changed
+     this can cause problems with some applications: e.g. those using the
+     certificate fingerprint for blacklists.
+
+     1. Reject signatures with non zero unused bits.
+
+     If the BIT STRING containing the signature has non zero unused bits reject
+     the signature. All current signature algorithms require zero unused bits.
+
+     2. Check certificate algorithm consistency.
+
+     Check the AlgorithmIdentifier inside TBS matches the one in the
+     certificate signature. NB: this will result in signature failure
+     errors for some broken certificates.
+
+     Thanks to Konrad Kraszewski from Google for reporting this issue.
+
+     3. Check DSA/ECDSA signatures use DER.
+
+     Reencode DSA/ECDSA signatures and compare with the original received
+     signature. Return an error if there is a mismatch.
+
+     This will reject various cases including garbage after signature
+     (thanks to Antti Karjalainen and Tuomo Untinen from the Codenomicon CROSS
+     program for discovering this case) and use of BER or invalid ASN.1 INTEGERs
+     (negative or with leading zeroes).
+
+     Further analysis was conducted and fixes were developed by Stephen Henson
+     of the OpenSSL core team.
+
+     (CVE-2014-8275)
+     [Steve Henson]
 
  Changes between 0.9.8zb and 0.9.8zc [15 Oct 2014]
 
diff --git a/crypto/asn1/a_verify.c b/crypto/asn1/a_verify.c
index 7ded69b170..3ef363d760 100644
--- a/crypto/asn1/a_verify.c
+++ b/crypto/asn1/a_verify.c
@@ -89,6 +89,12 @@ int ASN1_verify(i2d_of_void *i2d, X509_ALGOR *a, ASN1_BIT_STRING *signature,
 		ASN1err(ASN1_F_ASN1_VERIFY,ASN1_R_UNKNOWN_MESSAGE_DIGEST_ALGORITHM);
 		goto err;
 		}
+
+	if (signature->type == V_ASN1_BIT_STRING && signature->flags & 0x7)
+		{
+		ASN1err(ASN1_F_ASN1_VERIFY, ASN1_R_INVALID_BIT_STRING_BITS_LEFT);
+		goto err;
+		}
 	
 	inl=i2d(data,NULL);
 	buf_in=OPENSSL_malloc((unsigned int)inl);
@@ -144,6 +150,12 @@ int ASN1_item_verify(const ASN1_ITEM *it, X509_ALGOR *a, ASN1_BIT_STRING *signat
 		return -1;
 		}
 
+	if (signature->type == V_ASN1_BIT_STRING && signature->flags & 0x7)
+		{
+		ASN1err(ASN1_F_ASN1_VERIFY, ASN1_R_INVALID_BIT_STRING_BITS_LEFT);
+		return -1;
+		}
+
 	EVP_MD_CTX_init(&ctx);
 	i=OBJ_obj2nid(a->algorithm);
 	type=EVP_get_digestbyname(OBJ_nid2sn(i));
diff --git a/crypto/dsa/dsa_asn1.c b/crypto/dsa/dsa_asn1.c
index bc7d7a02a3..08d47720fa 100644
--- a/crypto/dsa/dsa_asn1.c
+++ b/crypto/dsa/dsa_asn1.c
@@ -200,7 +200,11 @@ int DSA_verify(int type, const unsigned char *dgst, int dgst_len,
 	     const unsigned char *sigbuf, int siglen, DSA *dsa)
 	{
 	DSA_SIG *s;
+	const unsigned char *p = sigbuf;
+	unsigned char *der = NULL;
+	int derlen = -1;
 	int ret=-1;
+
 #ifdef OPENSSL_FIPS
 	if(FIPS_mode() && !(dsa->flags & DSA_FLAG_NON_FIPS_ALLOW))
 		{
@@ -211,10 +215,18 @@ int DSA_verify(int type, const unsigned char *dgst, int dgst_len,
 
 	s = DSA_SIG_new();
 	if (s == NULL) return(ret);
-	if (d2i_DSA_SIG(&s,&sigbuf,siglen) == NULL) goto err;
+	if (d2i_DSA_SIG(&s,&p,siglen) == NULL) goto err;
+	/* Ensure signature uses DER and doesn't have trailing garbage */
+	derlen = i2d_DSA_SIG(s, &der);
+	if (derlen != siglen || memcmp(sigbuf, der, derlen))
+		goto err;
 	ret=DSA_do_verify(dgst,dgst_len,s,dsa);
 err:
+	if (derlen > 0)
+		{
+		OPENSSL_cleanse(der, derlen);
+		OPENSSL_free(der);
+		}
 	DSA_SIG_free(s);
 	return(ret);
 	}
-
diff --git a/crypto/ecdsa/ecs_vrf.c b/crypto/ecdsa/ecs_vrf.c
index ef9acf7b61..2836efe5ef 100644
--- a/crypto/ecdsa/ecs_vrf.c
+++ b/crypto/ecdsa/ecs_vrf.c
@@ -57,6 +57,7 @@
  */
 
 #include "ecs_locl.h"
+#include "cryptlib.h"
 #ifndef OPENSSL_NO_ENGINE
 #include <openssl/engine.h>
 #endif
@@ -84,13 +85,25 @@ int ECDSA_verify(int type, const unsigned char *dgst, int dgst_len,
 		const unsigned char *sigbuf, int sig_len, EC_KEY *eckey)
  	{
 	ECDSA_SIG *s;
+	const unsigned char *p = sigbuf;
+	unsigned char *der = NULL;
+	int derlen = -1;
 	int ret=-1;
 
 	s = ECDSA_SIG_new();
 	if (s == NULL) return(ret);
-	if (d2i_ECDSA_SIG(&s, &sigbuf, sig_len) == NULL) goto err;
+	if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) goto err;
+	/* Ensure signature uses DER and doesn't have trailing garbage */
+	derlen = i2d_ECDSA_SIG(s, &der);
+	if (derlen != sig_len || memcmp(sigbuf, der, derlen))
+		goto err;
 	ret=ECDSA_do_verify(dgst, dgst_len, s, eckey);
 err:
+	if (derlen > 0)
+		{
+		OPENSSL_cleanse(der, derlen);
+		OPENSSL_free(der);
+		}
 	ECDSA_SIG_free(s);
 	return(ret);
 	}
diff --git a/crypto/x509/x_all.c b/crypto/x509/x_all.c
index c7b07f7c9d..f4c68fc17c 100644
--- a/crypto/x509/x_all.c
+++ b/crypto/x509/x_all.c
@@ -73,6 +73,8 @@
 
 int X509_verify(X509 *a, EVP_PKEY *r)
 	{
+	if (X509_ALGOR_cmp(a->sig_alg, a->cert_info->signature))
+		return 0;
 	return(ASN1_item_verify(ASN1_ITEM_rptr(X509_CINF),a->sig_alg,
 		a->signature,a->cert_info,r));
 	}