[git] GPGME - branch, master, updated. gpgme-1.11.1-8-g8a0c8c5

[by Werner Koch]

This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GnuPG Made Easy".

The branch, master has been updated
       via  8a0c8c52510d9c2d934f85159f04b666286b1786 (commit)
      from  e54b110aec3165a32ff9551d0c5227b88aa3dd4f (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit 8a0c8c52510d9c2d934f85159f04b666286b1786
Author: Werner Koch <wk at gnupg.org>
Date:   Thu May 17 09:14:40 2018 +0200

    core: Always fail if an OpenPG message is not integrity protected.
    
    * src/decrypt.c (struct op_data_t): Add field not_integrity_protected.
    (parse_decryption_info): Set this.  Also rename mode to aead_algo for
    clarity.
    (_gpgme_decrypt_status_handler): Force failure in case of a missing
    MDC.
    --
    
    This extra check makes sure that a missing or stripped MDC in
     - gpg < 2.1
     - or gpg 2.2 with an old cipher algorithm
    will lead to a decryption failure.  gpg 2.3 will always fail in this
    case.  Implementing this check here and not backporting the 2.3 change
    to 2.2 has the benefit that all GPGME using applications are protected
    but scripts relying on rfc2440 (i.e. without MDC) will only break when
    migrating to 2.3.
    
    Note that S/MIME has no integrity protection mechanism but gpgsm
    neither emits a DECRYPTION_INFO status line, so an error will not be
    triggered.  If in the future gpgsm supports authenticated encryption
    it may issue a DECRYPTION_INFO line to force a failure here but it
    will in that case also emit a DECRYPTION_FAILED anyway.
    
    GnuPG-bug-id: 3981
    Signed-off-by: Werner Koch <wk at gnupg.org>

diff --git a/NEWS b/NEWS
index 80c0119..1eacccc 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,9 @@
 Noteworthy changes in version 1.11.2 (unreleased)
 -------------------------------------------------
 
+ * Even for old versions of gpg a missing MDC will now lead to a
+   decryption failure.
+
 
 Noteworthy changes in version 1.11.1 (2018-04-20)
 -------------------------------------------------
diff --git a/doc/gpgme.texi b/doc/gpgme.texi
index c4a29d5..c745675 100644
--- a/doc/gpgme.texi
+++ b/doc/gpgme.texi
@@ -5408,7 +5408,7 @@ or @code{gpgme_get_ctx_flag (ctx, "export-session-key")} returns true
 @since{1.11.0}
 
 A string with the symmetric encryption algorithm and mode using the
-format "<algo>.<mode>".  Note that old non-MDC encryption mode of
+format "<algo>.<mode>".  Note that the deprecated non-MDC encryption mode of
 OpenPGP is given as "PGPCFB".
 
 @end table
diff --git a/src/decrypt.c b/src/decrypt.c
index 0fc7019..ecd9c14 100644
--- a/src/decrypt.c
+++ b/src/decrypt.c
@@ -56,6 +56,11 @@ typedef struct
    * message that the general DECRYPTION_FAILED. */
   int any_no_seckey;
 
+  /* If the engine emits a DECRYPTION_INFO status and that does not
+   * indicate that an integrity proetction mode is active, this flag
+   * is set.  */
+  int not_integrity_protected;
+
   /* A pointer to the next pointer of the last recipient in the list.
      This makes appending new invalid signers painless while
      preserving the order.  */
@@ -280,7 +285,7 @@ parse_decryption_info (char *args, op_data_t opd, gpgme_protocol_t protocol)
   char *field[3];
   int nfields;
   char *args2;
-  int mdc, mode;
+  int mdc, aead_algo;
   const char *algostr, *modestr;
 
   if (!args)
@@ -296,19 +301,22 @@ parse_decryption_info (char *args, op_data_t opd, gpgme_protocol_t protocol)
 
   mdc     = atoi (field[0]);
   algostr = _gpgme_cipher_algo_name (atoi (field[1]), protocol);
-  mode    = nfields < 3? 0 : atoi (field[2]);
-  modestr = _gpgme_cipher_mode_name (mode, protocol);
+  aead_algo    = nfields < 3? 0 : atoi (field[2]);
+  modestr = _gpgme_cipher_mode_name (aead_algo, protocol);
 
   free (args2);
 
   free (opd->result.symkey_algo);
-  if (!mode && mdc != 2)
+  if (!aead_algo && mdc != 2)
     opd->result.symkey_algo = _gpgme_strconcat (algostr, ".PGPCFB", NULL);
   else
     opd->result.symkey_algo = _gpgme_strconcat (algostr, ".", modestr, NULL);
   if (!opd->result.symkey_algo)
     return gpg_error_from_syserror ();
 
+  if (!mdc && !aead_algo)
+    opd->not_integrity_protected = 1;
+
   return 0;
 }
 
@@ -338,13 +346,18 @@ _gpgme_decrypt_status_handler (void *priv, gpgme_status_code_t code,
       break;
 
     case GPGME_STATUS_EOF:
-      /* FIXME: These error values should probably be attributed to
-	 the underlying crypto engine (as error source).  */
+      /* We force an encryption failure if we know that integrity
+       * protection is missing.  For modern version of gpg using
+       * modern cipher algorithms this is not required because gpg
+       * will issue a failure anyway.  However older gpg versions emit
+       * only a warning.
+       * Fixme: These error values should probably be attributed to
+       * the underlying crypto engine (as error source).  */
       if (opd->failed && opd->pkdecrypt_failed)
         return opd->pkdecrypt_failed;
       else if (opd->failed && opd->any_no_seckey)
 	return gpg_error (GPG_ERR_NO_SECKEY);
-      else if (opd->failed)
+      else if (opd->failed || opd->not_integrity_protected)
 	return gpg_error (GPG_ERR_DECRYPT_FAILED);
       else if (!opd->okay)
 	return gpg_error (GPG_ERR_NO_DATA);

-----------------------------------------------------------------------

Summary of changes:
 NEWS           |  3 +++
 doc/gpgme.texi |  2 +-
 src/decrypt.c  | 27 ++++++++++++++++++++-------
 3 files changed, 24 insertions(+), 8 deletions(-)


hooks/post-receive
-- 
GnuPG Made Easy
http://git.gnupg.org