better translate libcrypto errors by looking deeper in the accursed

error stack for codes that indicate the wrong passphrase was supplied
for a PEM key. bz#2699 ok dtucker@

diff --git a/usr.bin/ssh/sshkey.c b/usr.bin/ssh/sshkey.c
index 8587661..8ed245e 100644 (file)
--- a/usr.bin/ssh/sshkey.c
+++ b/usr.bin/ssh/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.51 2017/05/31 09:15:42 deraadt Exp $ */
+/* $OpenBSD: sshkey.c,v 1.52 2017/06/09 06:40:24 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -1303,7 +1303,7 @@ sshkey_to_base64(const struct sshkey *key, char **b64p)
        return r;
 }
 
-static int
+int
 sshkey_format_text(const struct sshkey *key, struct sshbuf *b)
 {
        int r = SSH_ERR_INTERNAL_ERROR;
@@ -3313,6 +3313,64 @@ sshkey_private_to_fileblob(struct sshkey *key, struct sshbuf *blob,
 
 
 #ifdef WITH_OPENSSL
+static int
+translate_libcrypto_error(unsigned long pem_err)
+{
+       int pem_reason = ERR_GET_REASON(pem_err);
+
+       switch (ERR_GET_LIB(pem_err)) {
+       case ERR_LIB_PEM:
+               switch (pem_reason) {
+               case PEM_R_BAD_PASSWORD_READ:
+               case PEM_R_PROBLEMS_GETTING_PASSWORD:
+               case PEM_R_BAD_DECRYPT:
+                       return SSH_ERR_KEY_WRONG_PASSPHRASE;
+               default:
+                       return SSH_ERR_INVALID_FORMAT;
+               }
+       case ERR_LIB_EVP:
+               switch (pem_reason) {
+               case EVP_R_BAD_DECRYPT:
+                       return SSH_ERR_KEY_WRONG_PASSPHRASE;
+               case EVP_R_BN_DECODE_ERROR:
+               case EVP_R_DECODE_ERROR:
+#ifdef EVP_R_PRIVATE_KEY_DECODE_ERROR
+               case EVP_R_PRIVATE_KEY_DECODE_ERROR:
+#endif
+                       return SSH_ERR_INVALID_FORMAT;
+               default:
+                       return SSH_ERR_LIBCRYPTO_ERROR;
+               }
+       case ERR_LIB_ASN1:
+               return SSH_ERR_INVALID_FORMAT;
+       }
+       return SSH_ERR_LIBCRYPTO_ERROR;
+}
+
+static void
+clear_libcrypto_errors(void)
+{
+       while (ERR_get_error() != 0)
+               ;
+}
+
+/*
+ * Translate OpenSSL error codes to determine whether
+ * passphrase is required/incorrect.
+ */
+static int
+convert_libcrypto_error(void)
+{
+       /*
+        * Some password errors are reported at the beginning
+        * of the error queue.
+        */
+       if (translate_libcrypto_error(ERR_peek_error()) ==
+           SSH_ERR_KEY_WRONG_PASSPHRASE)
+               return SSH_ERR_KEY_WRONG_PASSPHRASE;
+       return translate_libcrypto_error(ERR_peek_last_error());
+}
+
 static int
 sshkey_parse_private_pem_fileblob(struct sshbuf *blob, int type,
     const char *passphrase, struct sshkey **keyp)
@@ -3333,46 +3391,10 @@ sshkey_parse_private_pem_fileblob(struct sshbuf *blob, int type,
                goto out;
        }
 
+       clear_libcrypto_errors();
        if ((pk = PEM_read_bio_PrivateKey(bio, NULL, NULL,
            (char *)passphrase)) == NULL) {
-               unsigned long pem_err = ERR_peek_last_error();
-               int pem_reason = ERR_GET_REASON(pem_err);
-
-               /*
-                * Translate OpenSSL error codes to determine whether
-                * passphrase is required/incorrect.
-                */
-               switch (ERR_GET_LIB(pem_err)) {
-               case ERR_LIB_PEM:
-                       switch (pem_reason) {
-                       case PEM_R_BAD_PASSWORD_READ:
-                       case PEM_R_PROBLEMS_GETTING_PASSWORD:
-                       case PEM_R_BAD_DECRYPT:
-                               r = SSH_ERR_KEY_WRONG_PASSPHRASE;
-                               goto out;
-                       default:
-                               r = SSH_ERR_INVALID_FORMAT;
-                               goto out;
-                       }
-               case ERR_LIB_EVP:
-                       switch (pem_reason) {
-                       case EVP_R_BAD_DECRYPT:
-                               r = SSH_ERR_KEY_WRONG_PASSPHRASE;
-                               goto out;
-                       case EVP_R_BN_DECODE_ERROR:
-                       case EVP_R_DECODE_ERROR:
-                       case EVP_R_PRIVATE_KEY_DECODE_ERROR:
-                               r = SSH_ERR_INVALID_FORMAT;
-                               goto out;
-                       default:
-                               r = SSH_ERR_LIBCRYPTO_ERROR;
-                               goto out;
-                       }
-               case ERR_LIB_ASN1:
-                       r = SSH_ERR_INVALID_FORMAT;
-                       goto out;
-               }
-               r = SSH_ERR_LIBCRYPTO_ERROR;
+               r = convert_libcrypto_error();
                goto out;
        }
        if (pk->type == EVP_PKEY_RSA &&