src: split CryptoPemCallback into two functions

Currently the function CryptoPemCallback is used for two things:
1. As a passphrase callback.
2. To avoid the default OpenSSL passphrase routine.

The default OpenSSL passphase routine would apply if both
the callback and the passphrase are null pointers and the typical
behaviour is to prompt for the passphase which is not appropriate in
node.

This commit suggests that the PasswordCallback function only handle
passphrases, and that an additional function named NoPasswordCallback
used for the second case to avoid OpenSSL's passphase routine.

PR-URL: #12827
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/node_crypto.cc

@@ -229,8 +229,6 @@ static void crypto_lock_cb(int mode, int n, const char* file, int line) {
 }
 
 
-// This callback is used by OpenSSL when it needs to query for the passphrase
-// which may be used for encrypted PEM structures.
 static int PasswordCallback(char *buf, int size, int rwflag, void *u) {
   if (u) {
     size_t buflen = static_cast<size_t>(size);
@@ -244,6 +242,16 @@ static int PasswordCallback(char *buf, int size, int rwflag, void *u) {
 }
 
 
+// This callback is used to avoid the default passphrase callback in OpenSSL
+// which will typically prompt for the passphrase. The prompting is designed
+// for the OpenSSL CLI, but works poorly for Node.js because it involves
+// synchronous interaction with the controlling terminal, something we never
+// want, and use this function to avoid it.
+static int NoPasswordCallback(char *buf, int size, int rwflag, void *u) {
+  return 0;
+}
+
+
 void ThrowCryptoError(Environment* env,
                       unsigned long err,  // NOLINT(runtime/int)
                       const char* default_message = nullptr) {
@@ -613,7 +621,7 @@ int SSL_CTX_use_certificate_chain(SSL_CTX* ctx,
   // that we are interested in
   ERR_clear_error();
 
-  x = PEM_read_bio_X509_AUX(in, nullptr, PasswordCallback, nullptr);
+  x = PEM_read_bio_X509_AUX(in, nullptr, NoPasswordCallback, nullptr);
 
   if (x == nullptr) {
     SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_CHAIN_FILE, ERR_R_PEM_LIB);
@@ -631,7 +639,10 @@ int SSL_CTX_use_certificate_chain(SSL_CTX* ctx,
     goto done;
   }
 
-  while ((extra = PEM_read_bio_X509(in, nullptr, PasswordCallback, nullptr))) {
+  while ((extra = PEM_read_bio_X509(in,
+                                    nullptr,
+                                    NoPasswordCallback,
+                                    nullptr))) {
     if (sk_X509_push(extra_certs, extra))
       continue;
 
@@ -728,7 +739,7 @@ static X509_STORE* NewRootCertStore() {
   if (root_certs_vector.empty()) {
     for (size_t i = 0; i < arraysize(root_certs); i++) {
       BIO* bp = NodeBIO::NewFixed(root_certs[i], strlen(root_certs[i]));
-      X509 *x509 = PEM_read_bio_X509(bp, nullptr, PasswordCallback, nullptr);
+      X509 *x509 = PEM_read_bio_X509(bp, nullptr, NoPasswordCallback, nullptr);
       BIO_free(bp);
 
       // Parse errors from the built-in roots are fatal.
@@ -771,7 +782,7 @@ void SecureContext::AddCACert(const FunctionCallbackInfo<Value>& args) {
 
   X509_STORE* cert_store = SSL_CTX_get_cert_store(sc->ctx_);
   while (X509* x509 =
-             PEM_read_bio_X509(bio, nullptr, PasswordCallback, nullptr)) {
+             PEM_read_bio_X509(bio, nullptr, NoPasswordCallback, nullptr)) {
     if (cert_store == root_cert_store) {
       cert_store = NewRootCertStore();
       SSL_CTX_set_cert_store(sc->ctx_, cert_store);
@@ -803,7 +814,7 @@ void SecureContext::AddCRL(const FunctionCallbackInfo<Value>& args) {
     return;
 
   X509_CRL* crl =
-      PEM_read_bio_X509_CRL(bio, nullptr, PasswordCallback, nullptr);
+      PEM_read_bio_X509_CRL(bio, nullptr, NoPasswordCallback, nullptr);
 
   if (crl == nullptr) {
     BIO_free_all(bio);
@@ -842,7 +853,7 @@ static unsigned long AddCertsFromFile(  // NOLINT(runtime/int)
   }
 
   while (X509* x509 =
-      PEM_read_bio_X509(bio, nullptr, PasswordCallback, nullptr)) {
+      PEM_read_bio_X509(bio, nullptr, NoPasswordCallback, nullptr)) {
     X509_STORE_add_cert(store, x509);
     X509_free(x509);
   }
@@ -4387,7 +4398,7 @@ SignBase::Error Verify::VerifyFinal(const char* key_pem,
   // Split this out into a separate function once we have more than one
   // consumer of public keys.
   if (strncmp(key_pem, PUBLIC_KEY_PFX, PUBLIC_KEY_PFX_LEN) == 0) {
-    pkey = PEM_read_bio_PUBKEY(bp, nullptr, PasswordCallback, nullptr);
+    pkey = PEM_read_bio_PUBKEY(bp, nullptr, NoPasswordCallback, nullptr);
     if (pkey == nullptr)
       goto exit;
   } else if (strncmp(key_pem, PUBRSA_KEY_PFX, PUBRSA_KEY_PFX_LEN) == 0) {
@@ -4403,7 +4414,7 @@ SignBase::Error Verify::VerifyFinal(const char* key_pem,
       goto exit;
   } else {
     // X.509 fallback
-    x509 = PEM_read_bio_X509(bp, nullptr, PasswordCallback, nullptr);
+    x509 = PEM_read_bio_X509(bp, nullptr, NoPasswordCallback, nullptr);
     if (x509 == nullptr)
       goto exit;
 
@@ -4530,7 +4541,7 @@ bool PublicKeyCipher::Cipher(const char* key_pem,
       goto exit;
   } else if (operation == kPublic &&
              strncmp(key_pem, CERTIFICATE_PFX, CERTIFICATE_PFX_LEN) == 0) {
-    x509 = PEM_read_bio_X509(bp, nullptr, PasswordCallback, nullptr);
+    x509 = PEM_read_bio_X509(bp, nullptr, NoPasswordCallback, nullptr);
     if (x509 == nullptr)
       goto exit;