gpg: Add "self-sigs-only" and "import-clean" to the keyserver options.

* g10/gpg.c (main): Change default.
--

Due to the DoS attack on the keyeservers we do not anymore default to
import key signatures.  That makes the keyserver unsuable for getting
keys for the WoT but it still allows to retriev keys - even if that
takes long to download the large keyblocks.

To revert to the old behavior add

  keyserver-optiions  no-self-sigs-only,no-import-clean

to gpg.conf.

GnuPG-bug-id: 4607
Signed-off-by: Werner Koch <[email protected]>
(cherry picked from commit 23c978640812d123eaffd4108744bdfcf48f7c93)

3 files changed, 26 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index 7c1906696..12927ba06 100644
--- a/NEWS
+++ b/NEWS
@@ -1,9 +1,27 @@
 Noteworthy changes in version 2.2.17 (unreleased)
 -------------------------------------------------
 
+  * gpg: Ignore all key-signatures received from keyservers.  This
+    change is required to mitigate a DoS due to keys flooded with
+    faked key-signatures.  The old behaviour can be achieved by adding
+      keyserver-options no-self-sigs-only,no-import-clean
+    to your gpg.conf.  [#4607]
+
+  * gpg: If an imported keyblocks is too large to be stored in the
+    keybox (pubring.kbx) do not error out but fallback to an import
+    using the options "self-sigs-only,import-clean".  [#4591]
+
+  * gpg: New command --locate-external-key which can be used to
+    refresh keys from the Web Key Directory or via other methods
+    configured with --auto-key-locate.
+
+  * gpg: New import option "self-sigs-only".
+
   * dirmngr: Support the "openpgpkey" subdomain feature from
     draft-koch-openpgp-webkey-service-07. [#4590].
 
+  Release-info: https://dev.gnupg.org/T4606
+
 
 Noteworthy changes in version 2.2.16 (2019-05-28)
 -------------------------------------------------
diff --git a/doc/gpg.texi b/doc/gpg.texi
index 11193afdb..0d76db06b 100644
--- a/doc/gpg.texi
+++ b/doc/gpg.texi
@@ -1917,6 +1917,11 @@ are available for all keyserver types, some common options are:
 
 @end table
 
+The default list of options is: "self-sigs-only, import-clean,
+repair-keys, repair-pks-subkey-bug, export-attributes,
+honor-pka-record".
+
+
 @item --completes-needed @var{n}
 @opindex compliant-needed
 Number of completely trusted users to introduce a new
diff --git a/g10/gpg.c b/g10/gpg.c
index d57146bb4..2c784d491 100644
--- a/g10/gpg.c
+++ b/g10/gpg.c
@@ -2375,7 +2375,9 @@ main (int argc, char **argv)
     opt.import_options = IMPORT_REPAIR_KEYS;
     opt.export_options = EXPORT_ATTRIBUTES;
     opt.keyserver_options.import_options = (IMPORT_REPAIR_KEYS
-					    | IMPORT_REPAIR_PKS_SUBKEY_BUG);
+					    | IMPORT_REPAIR_PKS_SUBKEY_BUG
+                                            | IMPORT_SELF_SIGS_ONLY
+                                            | IMPORT_CLEAN);
     opt.keyserver_options.export_options = EXPORT_ATTRIBUTES;
     opt.keyserver_options.options = KEYSERVER_HONOR_PKA_RECORD;
     opt.verify_options = (LIST_SHOW_UID_VALIDITY