gpg: Set a limit for a WKD import of 256 KiB.

* g10/call-dirmngr.c (MAX_WKD_RESULT_LENGTH): New.
(gpg_dirmngr_wkd_get): Use it.
--

WKD should return only a single key with just one UID.  For key
rollover 2 keys may be send.  A total of 256 KiB seems to be a
generous limit here.

Signed-off-by: Werner Koch <[email protected]>
(cherry picked from commit e88f56f1937ac92f6a3b94e50b6db2649ec0be41)

1 files changed, 9 insertions, 1 deletions

diff --git a/g10/call-dirmngr.c b/g10/call-dirmngr.c
index 9bc90fb2d..d086cefca 100644
--- a/g10/call-dirmngr.c
+++ b/g10/call-dirmngr.c
@@ -41,6 +41,12 @@
 #include "call-dirmngr.h"
 
 
+/* Keys retrieved from the web key directory should be small.  There
+ * is only one UID and we can expect that the number of subkeys is
+ * reasonable.  So we set a generous limit of 256 KiB.  */
+#define MAX_WKD_RESULT_LENGTH   (256 * 1024)
+
+
 /* Parameter structure used to gather status info.  Note that it is
  * also used for WKD requests.  */
 struct ks_status_parm_s
@@ -1365,7 +1371,7 @@ gpg_dirmngr_wkd_get (ctrl_t ctrl, const char *name, int quick,
       goto leave;
     }
 
-  parm.memfp = es_fopenmem (0, "rwb");
+  parm.memfp = es_fopenmem (MAX_WKD_RESULT_LENGTH, "rwb");
   if (!parm.memfp)
     {
       err = gpg_error_from_syserror ();
@@ -1373,6 +1379,8 @@ gpg_dirmngr_wkd_get (ctrl_t ctrl, const char *name, int quick,
     }
   err = assuan_transact (ctx, line, dns_cert_data_cb, &parm,
                          NULL, NULL, ks_status_cb, &stparm);
+  if (gpg_err_code (err) == GPG_ERR_ENOSPC)
+    err = gpg_error (GPG_ERR_TOO_LARGE);
   if (err)
     goto leave;