core: New context flag "ignore-mdc-error".

* src/context.h (gpgme_context): Add field ignore_mdc_error.
* src/gpgme.c (gpgme_set_ctx_flag, gpgme_get_ctx_flag): Set/get it.
* src/engine-gpg.c (engine_gpg): Add flags.ignore_mdc_error.
(gpg_set_engine_flags): Set it.
(build_argv): Pass option to gpg.
* src/decrypt.c (_gpgme_decrypt_status_handler): Take care of flag.
(gpgme_op_decrypt_result): Clear flag.
(gpgme_op_decrypt): Clear flag.
* src/decrypt-verify.c (gpgme_op_decrypt_verify): Clear flag
(gpgme_op_decrypt_ext): Clear flag.

* tests/run-decrypt.c (show_usage): Add option --ignore-mdc-error.

Signed-off-by: Werner Koch <wk@gnupg.org>

diff --git a/NEWS b/NEWS
index bc1330a..4eb3dbe 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,7 @@ Noteworthy changes in version 1.11.2 (unreleased)
  * Interface changes relative to the 1.11.1 release:
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  gpgme_decrypt_result_t           EXTENDED: New field legacy_cipher_nomdc.
  * Interface changes relative to the 1.11.1 release:
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  gpgme_decrypt_result_t           EXTENDED: New field legacy_cipher_nomdc.

+ gpgme_set_ctx_flag               EXTENDED: New flag 'ignore-mdc-error'.

  cpp: DecryptionResult::sessionKey     NEW.
  cpp: DecryptionResult::symkeyAlgo     NEW.
  cpp: Data::rewind                     NEW.
  cpp: DecryptionResult::sessionKey     NEW.
  cpp: DecryptionResult::symkeyAlgo     NEW.
  cpp: Data::rewind                     NEW.

diff --git a/doc/gpgme.texi b/doc/gpgme.texi
index d877116..e3445a0 100644 (file)
--- a/doc/gpgme.texi
+++ b/doc/gpgme.texi
@@ -3078,7 +3078,7 @@ the time when you verified the signature.
 The string given in @var{value} is passed to the GnuPG engines to
 request restrictions based on the origin of the request.  Valid values
 are documented in the GnuPG manual and the gpg man page under the
 The string given in @var{value} is passed to the GnuPG engines to
 request restrictions based on the origin of the request.  Valid values
 are documented in the GnuPG manual and the gpg man page under the

-option ``--request-origin''.  Requires at least GnuPG 2.2.6 to have an
+option @option{--request-origin}.  Requires at least GnuPG 2.2.6 to have an

 effect.
 
 @item "no-symkey-cache"
 effect.
 
 @item "no-symkey-cache"


@@ -3086,6 +3086,15 @@ For OpenPGP disable the passphrase cache used for symmetrical en- and
 decryption.  This cache is based on the message specific salt value.
 Requires at least GnuPG 2.2.7 to have an effect.
 
 decryption.  This cache is based on the message specific salt value.
 Requires at least GnuPG 2.2.7 to have an effect.
 

+@item "ignore-mdc-error"
+This flag passes the option @option{--ignore-mdc-error} to gpg.  This
+can be used to force decryption of a message which failed due to a
+missing integrity check.  This flag must be used with great caution
+and only if it is a known non-corrupted old message and the decryption
+result of the former try had the decryption result flag
+@code{legacy_cipher_nomdc} set.  For failsafe reasons this flag is
+reset after each operation.
+

 @end table
 
 This function returns @code{0} on success.
 @end table
 
 This function returns @code{0} on success.

diff --git a/src/context.h b/src/context.h
index c8e75ba..bdab687 100644 (file)
--- a/src/context.h
+++ b/src/context.h
@@ -124,6 +124,10 @@ struct gpgme_context
   /* Do not use the symmtric encryption passphrase cache.  */
   unsigned int no_symkey_cache : 1;
 
   /* Do not use the symmtric encryption passphrase cache.  */
   unsigned int no_symkey_cache : 1;
 

+  /* Pass --ignore-mdc-error to gpg.  Note that this flag is reset
+   * after the operation.  */
+  unsigned int ignore_mdc_error : 1;
+

   /* Flags for keylist mode.  */
   gpgme_keylist_mode_t keylist_mode;
 
   /* Flags for keylist mode.  */
   gpgme_keylist_mode_t keylist_mode;
 

diff --git a/src/decrypt-verify.c b/src/decrypt-verify.c
index ce4a7a9..1bd81c3 100644 (file)
--- a/src/decrypt-verify.c
+++ b/src/decrypt-verify.c
@@ -127,6 +127,7 @@ gpgme_op_decrypt_verify (gpgme_ctx_t ctx, gpgme_data_t cipher,
   err = decrypt_verify_start (ctx, 1, GPGME_DECRYPT_VERIFY, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);
   err = decrypt_verify_start (ctx, 1, GPGME_DECRYPT_VERIFY, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);

+  ctx->ignore_mdc_error = 0;  /* Always reset.  */

   return TRACE_ERR (err);
 }
 
   return TRACE_ERR (err);
 }
 


@@ -177,5 +178,6 @@ gpgme_op_decrypt_ext (gpgme_ctx_t ctx,
     err = _gpgme_decrypt_start (ctx, 1, flags, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);
     err = _gpgme_decrypt_start (ctx, 1, flags, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);

+  ctx->ignore_mdc_error = 0;  /* Always reset.  */

   return TRACE_ERR (err);
 }
   return TRACE_ERR (err);
 }

diff --git a/src/decrypt.c b/src/decrypt.c
index f2278d8..8c95ebe 100644 (file)
--- a/src/decrypt.c
+++ b/src/decrypt.c
@@ -97,6 +97,8 @@ gpgme_op_decrypt_result (gpgme_ctx_t ctx)
 
   TRACE_BEG (DEBUG_CTX, "gpgme_op_decrypt_result", ctx);
 
 
   TRACE_BEG (DEBUG_CTX, "gpgme_op_decrypt_result", ctx);
 

+  ctx->ignore_mdc_error = 0;  /* Always reset this flag.  */
+

   err = _gpgme_op_data_lookup (ctx, OPDATA_DECRYPT, &hook, -1, NULL);
   opd = hook;
   if (err || !opd)
   err = _gpgme_op_data_lookup (ctx, OPDATA_DECRYPT, &hook, -1, NULL);
   opd = hook;
   if (err || !opd)


@@ -362,7 +364,8 @@ _gpgme_decrypt_status_handler (void *priv, gpgme_status_code_t code,
         return opd->pkdecrypt_failed;
       else if (opd->failed && opd->any_no_seckey)
        return gpg_error (GPG_ERR_NO_SECKEY);
         return opd->pkdecrypt_failed;
       else if (opd->failed && opd->any_no_seckey)
        return gpg_error (GPG_ERR_NO_SECKEY);

-      else if (opd->failed || opd->not_integrity_protected)
+      else if (opd->failed || (opd->not_integrity_protected
+                               && !ctx->ignore_mdc_error))

        return gpg_error (GPG_ERR_DECRYPT_FAILED);
       else if (!opd->okay)
        return gpg_error (GPG_ERR_NO_DATA);
        return gpg_error (GPG_ERR_DECRYPT_FAILED);
       else if (!opd->okay)
        return gpg_error (GPG_ERR_NO_DATA);


@@ -564,5 +567,6 @@ gpgme_op_decrypt (gpgme_ctx_t ctx, gpgme_data_t cipher, gpgme_data_t plain)
   err = _gpgme_decrypt_start (ctx, 1, 0, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);
   err = _gpgme_decrypt_start (ctx, 1, 0, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);

+  ctx->ignore_mdc_error = 0;  /* Always reset.  */

   return TRACE_ERR (err);
 }
   return TRACE_ERR (err);
 }

diff --git a/src/engine-gpg.c b/src/engine-gpg.c
index 43d49fe..802af08 100644 (file)
--- a/src/engine-gpg.c
+++ b/src/engine-gpg.c
@@ -144,6 +144,7 @@ struct engine_gpg
   struct {
     unsigned int no_symkey_cache : 1;
     unsigned int offline : 1;
   struct {
     unsigned int no_symkey_cache : 1;
     unsigned int offline : 1;

+    unsigned int ignore_mdc_error : 1;

   } flags;
 
   /* NULL or the data object fed to --override_session_key-fd.  */
   } flags;
 
   /* NULL or the data object fed to --override_session_key-fd.  */


@@ -646,9 +647,10 @@ gpg_set_engine_flags (void *engine, const gpgme_ctx_t ctx)
 
   gpg->flags.no_symkey_cache = (ctx->no_symkey_cache
                                 && have_gpg_version (gpg, "2.2.7"));
 
   gpg->flags.no_symkey_cache = (ctx->no_symkey_cache
                                 && have_gpg_version (gpg, "2.2.7"));

-

   gpg->flags.offline = (ctx->offline && have_gpg_version (gpg, "2.1.23"));
 
   gpg->flags.offline = (ctx->offline && have_gpg_version (gpg, "2.1.23"));
 

+  gpg->flags.ignore_mdc_error = !!ctx->ignore_mdc_error;
+

 }
 
 
 }
 
 


@@ -955,6 +957,19 @@ build_argv (engine_gpg_t gpg, const char *pgmname)
       argc++;
     }
 
       argc++;
     }
 

+  if (gpg->flags.ignore_mdc_error)
+    {
+      argv[argc] = strdup ("--ignore-mdc-error");
+      if (!argv[argc])
+       {
+          int saved_err = gpg_error_from_syserror ();
+         free (fd_data_map);
+         free_argv (argv);
+         return saved_err;
+        }
+      argc++;
+    }
+

   if (gpg->flags.offline)
     {
       argv[argc] = strdup ("--disable-dirmngr");
   if (gpg->flags.offline)
     {
       argv[argc] = strdup ("--disable-dirmngr");

diff --git a/src/gpgme.c b/src/gpgme.c
index 82d6747..b03c7b8 100644 (file)
--- a/src/gpgme.c
+++ b/src/gpgme.c
@@ -542,6 +542,10 @@ gpgme_set_ctx_flag (gpgme_ctx_t ctx, const char *name, const char *value)
     {
       ctx->no_symkey_cache = abool;
     }
     {
       ctx->no_symkey_cache = abool;
     }

+  else if (!strcmp (name, "ignore-mdc-error"))
+    {
+      ctx->ignore_mdc_error = abool;
+    }

   else
     err = gpg_error (GPG_ERR_UNKNOWN_NAME);
 
   else
     err = gpg_error (GPG_ERR_UNKNOWN_NAME);
 


@@ -591,6 +595,10 @@ gpgme_get_ctx_flag (gpgme_ctx_t ctx, const char *name)
     {
       return ctx->no_symkey_cache? "1":"";
     }
     {
       return ctx->no_symkey_cache? "1":"";
     }

+  else if (!strcmp (name, "ignore-mdc-error"))
+    {
+      return ctx->ignore_mdc_error? "1":"";
+    }

   else
     return NULL;
 }
   else
     return NULL;
 }

diff --git a/tests/run-decrypt.c b/tests/run-decrypt.c
index 8ec0cb4..99a15c7 100644 (file)
--- a/tests/run-decrypt.c
+++ b/tests/run-decrypt.c
@@ -86,6 +86,7 @@ show_usage (int ex)
          "  --override-session-key STRING   use STRING as session key\n"
          "  --request-origin STRING         use STRING as request origin\n"
          "  --no-symkey-cache               disable the use of that cache\n"
          "  --override-session-key STRING   use STRING as session key\n"
          "  --request-origin STRING         use STRING as request origin\n"
          "  --no-symkey-cache               disable the use of that cache\n"

+         "  --ignore-mdc-error              allow decryption of legacy data\n"

          "  --unwrap         remove only the encryption layer\n"
          , stderr);
   exit (ex);
          "  --unwrap         remove only the encryption layer\n"
          , stderr);
   exit (ex);


@@ -109,6 +110,7 @@ main (int argc, char **argv)
   const char *override_session_key = NULL;
   const char *request_origin = NULL;
   int no_symkey_cache = 0;
   const char *override_session_key = NULL;
   const char *request_origin = NULL;
   int no_symkey_cache = 0;

+  int ignore_mdc_error = 0;

   int raw_output = 0;
 
   if (argc)
   int raw_output = 0;
 
   if (argc)


@@ -170,6 +172,11 @@ main (int argc, char **argv)
           no_symkey_cache = 1;
           argc--; argv++;
         }
           no_symkey_cache = 1;
           argc--; argv++;
         }

+      else if (!strcmp (*argv, "--ignore-mdc-error"))
+        {
+          ignore_mdc_error = 1;
+          argc--; argv++;
+        }

       else if (!strcmp (*argv, "--unwrap"))
         {
           flags |= GPGME_DECRYPT_UNWRAP;
       else if (!strcmp (*argv, "--unwrap"))
         {
           flags |= GPGME_DECRYPT_UNWRAP;


@@ -241,7 +248,18 @@ main (int argc, char **argv)
       err = gpgme_set_ctx_flag (ctx, "no-symkey-cache", "1");
       if (err)
         {
       err = gpgme_set_ctx_flag (ctx, "no-symkey-cache", "1");
       if (err)
         {

-          fprintf (stderr, PGM ": error setting no-symkey-cache:  %s\n",
+          fprintf (stderr, PGM ": error setting no-symkey-cache: %s\n",
+                   gpgme_strerror (err));
+          exit (1);
+        }
+    }
+
+  if (ignore_mdc_error)
+    {
+      err = gpgme_set_ctx_flag (ctx, "ignore-mdc-error", "1");
+      if (err)
+        {
+          fprintf (stderr, PGM ": error setting ignore-mdc-error: %s\n",

                    gpgme_strerror (err));
           exit (1);
         }
                    gpgme_strerror (err));
           exit (1);
         }