Update net/third_party/nss to NSS 3.15.4.

net/third_party/nss/patches/tls12backuphash2.patch

-diff --git a/net/third_party/nss/ssl/ssl3con.c b/net/third_party/nss/ssl/ssl3con.c
-index 06992e0..cf7ef32 100644
---- a/net/third_party/nss/ssl/ssl3con.c
-+++ b/net/third_party/nss/ssl/ssl3con.c
-@@ -6973,14 +6973,27 @@ no_memory:      /* no-memory error has already been set. */
- 
- 
- /*
-- * Returns true if the client authentication key is an RSA or DSA key that
-- * may be able to sign only SHA-1 hashes.
-+ * Returns the TLS signature algorithm for the client authentication key and
-+ * whether it is an RSA or DSA key that may be able to sign only SHA-1 hashes.
-  */
--static PRBool
--ssl3_ClientKeyPrefersSHA1(sslSocket *ss)
-+static SECStatus
-+ssl3_ExtractClientKeyInfo(sslSocket *ss,
-+                         TLSSignatureAlgorithm *sigAlg,
-+                         PRBool *preferSha1)
- {
-+    SECStatus rv = SECSuccess;
-     SECKEYPublicKey *pubk;
--    PRBool prefer_sha1 = PR_FALSE;
-+
-+    pubk = CERT_ExtractPublicKey(ss->ssl3.clientCertificate);
-+    if (pubk == NULL) {
-+       rv = SECFailure;
-+       goto done;
-+    }
-+
-+    rv = ssl3_TLSSignatureAlgorithmForKeyType(pubk->keyType, sigAlg);
-+    if (rv != SECSuccess) {
-+       goto done;
-+    }
- 
- #if defined(NSS_PLATFORM_CLIENT_AUTH) && defined(_WIN32)
-     /* If the key is in CAPI, assume conservatively that the CAPI service
-@@ -6989,7 +7002,8 @@ ssl3_ClientKeyPrefersSHA1(sslSocket *ss)
-     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. */
--       return PR_TRUE;
-+       *preferSha1 = PR_TRUE;
-+       goto done;
-     }
- #endif  /* NSS_PLATFORM_CLIENT_AUTH && _WIN32 */
- 
-@@ -6999,38 +7013,61 @@ ssl3_ClientKeyPrefersSHA1(sslSocket *ss)
-      * older, DSA key size is at most 1024 bits and the hash function must
-      * be SHA-1.
-      */
--    pubk = CERT_ExtractPublicKey(ss->ssl3.clientCertificate);
--    if (pubk == NULL) {
--       return PR_FALSE;
--    }
-     if (pubk->keyType == rsaKey || pubk->keyType == dsaKey) {
--       prefer_sha1 = SECKEY_PublicKeyStrength(pubk) <= 128;
-+       *preferSha1 = SECKEY_PublicKeyStrength(pubk) <= 128;
-+    } else {
-+       *preferSha1 = PR_FALSE;
-     }
--    SECKEY_DestroyPublicKey(pubk);
--    return prefer_sha1;
-+
-+  done:
-+    if (pubk)
-+       SECKEY_DestroyPublicKey(pubk);
-+    return rv;
- }
- 
--/* Destroys the backup handshake hash context if we don't need it. */
-+/* Destroys the backup handshake hash context if we don't need it. Note that
-+ * this function selects the hash algorithm for client authentication
-+ * signatures; ssl3_SendCertificateVerify uses the presence of the backup hash
-+ * to determine whether to use SHA-1 or SHA-256. */
- static void
- ssl3_DestroyBackupHandshakeHashIfNotNeeded(sslSocket *ss,
-                                           const SECItem *algorithms)
- {
--    PRBool need_backup_hash = PR_FALSE;
-+    SECStatus rv;
-+    TLSSignatureAlgorithm sigAlg;
-+    PRBool preferSha1;
-+    PRBool supportsSha1 = PR_FALSE;
-+    PRBool supportsSha256 = PR_FALSE;
-+    PRBool needBackupHash = PR_FALSE;
-     unsigned int i;
- 
-     PORT_Assert(ss->ssl3.hs.md5);
--    if (ssl3_ClientKeyPrefersSHA1(ss)) {
--       /* Use SHA-1 if the server supports it. */
--       for (i = 0; i < algorithms->len; i += 2) {
--           if (algorithms->data[i] == tls_hash_sha1 &&
--               (algorithms->data[i+1] == tls_sig_rsa ||
--                algorithms->data[i+1] == tls_sig_dsa)) {
--               need_backup_hash = PR_TRUE;
--               break;
-+
-+    /* Determine the key's signature algorithm and whether it prefers SHA-1. */
-+    rv = ssl3_ExtractClientKeyInfo(ss, &sigAlg, &preferSha1);
-+    if (rv != SECSuccess) {
-+       goto done;
-+    }
-+
-+    /* Determine the server's hash support for that signature algorithm. */
-+    for (i = 0; i < algorithms->len; i += 2) {
-+       if (algorithms->data[i+1] == sigAlg) {
-+           if (algorithms->data[i] == tls_hash_sha1) {
-+               supportsSha1 = PR_TRUE;
-+           } else if (algorithms->data[i] == tls_hash_sha256) {
-+               supportsSha256 = PR_TRUE;
-            }
-        }
-     }
--    if (!need_backup_hash) {
-+
-+    /* If either the server does not support SHA-256 or the client key prefers
-+     * SHA-1, leave the backup hash. */
-+    if (supportsSha1 && (preferSha1 || !supportsSha256)) {
-+       needBackupHash = PR_TRUE;
-+    }
-+
-+done:
-+    if (!needBackupHash) {
-        PK11_DestroyContext(ss->ssl3.hs.md5, PR_TRUE);
-        ss->ssl3.hs.md5 = NULL;
-     }