Prefer to generate SHA-1 signatures for TLS 1.2 client authentication if

net/third_party/nss/patches/tls12backuphash.patch

Index: net/third_party/nss/patches/tls12backuphash.patch
===================================================================
--- net/third_party/nss/patches/tls12backuphash.patch	(revision 220983)
+++ net/third_party/nss/patches/tls12backuphash.patch	(working copy)
@@ -1,13 +1,12 @@
 Index: net/third_party/nss/ssl/ssl3con.c
 ===================================================================
---- net/third_party/nss/ssl/ssl3con.c	(revision 219342)
+--- net/third_party/nss/ssl/ssl3con.c	(revision 220594)
 +++ net/third_party/nss/ssl/ssl3con.c	(working copy)
-@@ -3933,6 +3933,22 @@
+@@ -3933,6 +3933,20 @@
  		ssl_MapLowLevelError(SSL_ERROR_DIGEST_FAILURE);
  		return SECFailure;
  	    }
 +
-+#ifdef _WIN32
 +	    /* A backup SHA-1 hash for a potential client auth signature. */
 +	    if (!ss->sec.isServer) {
 +		ss->ssl3.hs.md5 = PK11_CreateDigestContext(SEC_OID_SHA1);
@@ -21,11 +20,10 @@
 +		    return SECFailure;
 +		}
 +	    }
-+#endif
  	} else {
  	    /* Both ss->ssl3.hs.md5 and ss->ssl3.hs.sha should be NULL or
  	     * created successfully. */
-@@ -4043,6 +4059,13 @@
+@@ -4043,6 +4057,13 @@
  	    ssl_MapLowLevelError(SSL_ERROR_DIGEST_FAILURE);
  	    return rv;
  	}
@@ -39,7 +37,7 @@
      } else {
  	rv = PK11_DigestOp(ss->ssl3.hs.md5, b, l);
  	if (rv != SECSuccess) {
-@@ -4791,6 +4814,30 @@
+@@ -4791,6 +4812,30 @@
      return rv;
  }
  
@@ -70,7 +68,7 @@
  /*
   * SSL 2 based implementations pass in the initial outbound buffer
   * so that the handshake hash can contain the included information.
-@@ -6044,7 +6091,17 @@
+@@ -6044,7 +6089,17 @@
  		SSL_GETPID(), ss->fd));
  
      ssl_GetSpecReadLock(ss);
@@ -89,7 +87,7 @@
      ssl_ReleaseSpecReadLock(ss);
      if (rv != SECSuccess) {
  	goto done;	/* err code was set by ssl3_ComputeHandshakeHashes */
-@@ -6098,11 +6155,6 @@
+@@ -6098,11 +6153,6 @@
  	if (rv != SECSuccess) {
  	    goto done;
  	}
@@ -101,21 +99,47 @@
  	sigAndHash.hashAlg = hashes.hashAlg;
  
  	rv = ssl3_AppendSignatureAndHashAlgorithm(ss, &sigAndHash);
-@@ -6994,6 +7046,31 @@
+@@ -6994,6 +7044,56 @@
  		}
  		goto send_no_certificate;
  	    }
 +
 +	    if (isTLS12 && ss->ssl3.hs.md5) {
 +		PRBool need_backup_hash = PR_FALSE;
++		PRBool prefer_sha1 = PR_FALSE;
 +#ifdef _WIN32
 +		/* If the key is in CAPI, assume conservatively that the CAPI
 +		 * service provider may be unable to sign SHA-256 hashes.
-+		 * Use SHA-1 if the server supports it. */
++		 */
 +		if (ss->ssl3.platformClientKey->dwKeySpec !=
 +		    CERT_NCRYPT_KEY_SPEC) {
++		    /* CAPI only supports RSA and DSA signatures, so we don't
++		     * need to check the key type. */
++		    prefer_sha1 = PR_TRUE;
++		}
++#endif  /* _WIN32 */
++		/* If the key is a 1024-bit RSA or DSA key, assume
++		 * conservatively that it may be unable to sign SHA-256
++		 * hashes. This is the case for older Estonian ID cards that
++		 * have 1024-bit RSA keys. In FIPS 186-2 and older, DSA key
++		 * size is at most 1024 bits and the hash function must be
++		 * SHA-1.
++		 */
++		if (!prefer_sha1) {
++		    SECKEYPublicKey *pubk =
++			CERT_ExtractPublicKey(ss->ssl3.clientCertificate);
++		    if (pubk == NULL) {
++			errCode = SSL_ERROR_EXTRACT_PUBLIC_KEY_FAILURE;
++ 			goto loser;
++		    }
++		    if (pubk->keyType == rsaKey || pubk->keyType == dsaKey) {
++			prefer_sha1 = SECKEY_PublicKeyStrength(pubk) <= 128;
++		    }
++		    SECKEY_DestroyPublicKey(pubk);
++		}
++		/* Use SHA-1 if the server supports it. */
++		if (prefer_sha1) {
 +		    for (i = 0; i < algorithms.len; i += 2) {
-+			/* CAPI only supports RSA and DSA signatures. */
 +			if (algorithms.data[i] == tls_hash_sha1 &&
 +			    (algorithms.data[i+1] == tls_sig_rsa ||
 +			     algorithms.data[i+1] == tls_sig_dsa)) {
@@ -124,7 +148,6 @@
 +			}
 +		    }
 +		}
-+#endif  /* _WIN32 */
 +		if (!need_backup_hash) {
 +		    PK11_DestroyContext(ss->ssl3.hs.md5, PR_TRUE);
 +		    ss->ssl3.hs.md5 = NULL;
@@ -133,7 +156,7 @@
  	    break;  /* not an error */
  	}
  #endif   /* NSS_PLATFORM_CLIENT_AUTH */
-@@ -7227,6 +7304,13 @@
+@@ -7227,6 +7327,13 @@
  		     (ss->ssl3.platformClientKey ||
  		     ss->ssl3.clientPrivateKey != NULL);
  
@@ -149,15 +172,15 @@
       * certificate to an attacker that does not have a valid cert for the
 Index: net/third_party/nss/ssl/sslimpl.h
 ===================================================================
---- net/third_party/nss/ssl/sslimpl.h	(revision 219342)
+--- net/third_party/nss/ssl/sslimpl.h	(revision 220594)
 +++ net/third_party/nss/ssl/sslimpl.h	(working copy)
 @@ -838,6 +838,9 @@
       * SSL 3.0 - TLS 1.1 use both |md5| and |sha|. |md5| is used for MD5 and
       * |sha| for SHA-1.
       * TLS 1.2 and later use only |sha|, for SHA-256. */
-+    /* NOTE: On Windows, TLS 1.2 and later use |md5| as a backup handshake hash
-+     * for generating client auth signatures. Confusingly, the backup hash
-+     * function is SHA-1. */
++    /* NOTE: On the client side, TLS 1.2 and later use |md5| as a backup
++     * handshake hash for generating client auth signatures. Confusingly, the
++     * backup hash function is SHA-1. */
      PK11Context *         md5;
      PK11Context *         sha;