don't choke on new-format private keys encrypted with an AEAD cipher;

bz#2366, patch from Ron Frederick; ok markus@

diff --git a/usr.bin/ssh/sshkey.c b/usr.bin/ssh/sshkey.c
index 7eb41f8..e9a23e7 100644 (file)
--- a/usr.bin/ssh/sshkey.c
+++ b/usr.bin/ssh/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.17 2015/05/04 06:10:48 djm Exp $ */
+/* $OpenBSD: sshkey.c,v 1.18 2015/05/08 03:17:49 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -3151,7 +3151,7 @@ sshkey_parse_private2(struct sshbuf *blob, int type, const char *passphrase,
        const u_char *cp;
        int r = SSH_ERR_INTERNAL_ERROR;
        size_t encoded_len;
-       size_t i, keylen = 0, ivlen = 0, slen = 0;
+       size_t i, keylen = 0, ivlen = 0, authlen = 0, slen = 0;
        struct sshbuf *encoded = NULL, *decoded = NULL;
        struct sshbuf *kdf = NULL, *decrypted = NULL;
        struct sshcipher_ctx ciphercontext;
@@ -3261,6 +3261,7 @@ sshkey_parse_private2(struct sshbuf *blob, int type, const char *passphrase,
        /* setup key */
        keylen = cipher_keylen(cipher);
        ivlen = cipher_ivlen(cipher);
+       authlen = cipher_authlen(cipher);
        if ((key = calloc(1, keylen + ivlen)) == NULL) {
                r = SSH_ERR_ALLOC_FAIL;
                goto out;
@@ -3276,19 +3277,25 @@ sshkey_parse_private2(struct sshbuf *blob, int type, const char *passphrase,
                }
        }
 
+       /* check that an appropriate amount of auth data is present */
+       if (sshbuf_len(decoded) < encrypted_len + authlen) {
+               r = SSH_ERR_INVALID_FORMAT;
+               goto out;
+       }
+
        /* decrypt private portion of key */
        if ((r = sshbuf_reserve(decrypted, encrypted_len, &dp)) != 0 ||
            (r = cipher_init(&ciphercontext, cipher, key, keylen,
            key + keylen, ivlen, 0)) != 0)
                goto out;
        if ((r = cipher_crypt(&ciphercontext, 0, dp, sshbuf_ptr(decoded),
-           sshbuf_len(decoded), 0, cipher_authlen(cipher))) != 0) {
+           encrypted_len, 0, authlen)) != 0) {
                /* an integrity error here indicates an incorrect passphrase */
                if (r == SSH_ERR_MAC_INVALID)
                        r = SSH_ERR_KEY_WRONG_PASSPHRASE;
                goto out;
        }
-       if ((r = sshbuf_consume(decoded, encrypted_len)) != 0)
+       if ((r = sshbuf_consume(decoded, encrypted_len + authlen)) != 0)
                goto out;
        /* there should be no trailing data */
        if (sshbuf_len(decoded) != 0) {