From 855d14d390e8dd8464f2f38187dbccb19a13e815 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Tue, 26 Jan 2021 17:42:55 +0100
Subject: [PATCH] scd: Extend iso7816_select_path

* scd/iso7816.c (iso7816_select_path): Add arg top_fd.
* scd/app-nks.c (do_readkey): Adjust for this change
(select_ef_by_path: Ditto.

* common/tlv.h: Include membuf.h.
--

Including membuf.h is just for easier backporting.  In 2.3 it is
actually required in tlv.h but in 2.2 we right now only use it
indirect.
---
 common/tlv.h  |  2 ++
 scd/app-nks.c |  2 +-
 scd/app-p15.c |  6 +++---
 scd/iso7816.c | 18 +++++++++++++-----
 scd/iso7816.h |  3 ++-
 5 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/common/tlv.h b/common/tlv.h
index ba4ea2e42..0894e5d05 100644
--- a/common/tlv.h
+++ b/common/tlv.h
@@ -30,6 +30,8 @@
 #ifndef SCD_TLV_H
 #define SCD_TLV_H 1
 
+#include "membuf.h"
+
 
 enum tlv_tag_class {
   CLASS_UNIVERSAL = 0,
diff --git a/scd/app-nks.c b/scd/app-nks.c
index 3cbf1e414..d7a4dbd36 100644
--- a/scd/app-nks.c
+++ b/scd/app-nks.c
@@ -628,7 +628,7 @@ do_readkey (app_t app, ctrl_t ctrl, const char *keyid, unsigned int flags,
     return gpg_error (GPG_ERR_UNSUPPORTED_OPERATION);
 
   /* Access the KEYD file which is always in the master directory.  */
-  err = iso7816_select_path (app->slot, path, DIM (path));
+  err = iso7816_select_path (app_get_slot (app), path, DIM (path), 0);
   if (err)
     return err;
   /* Due to the above select we need to re-select our application.  */
diff --git a/scd/app-p15.c b/scd/app-p15.c
index 21f7726cd..687c6ad32 100644
--- a/scd/app-p15.c
+++ b/scd/app-p15.c
@@ -501,7 +501,7 @@ select_ef_by_path (app_t app, const unsigned short *path, size_t pathlen)
 
   if (app->app_local->direct_path_selection)
     {
-      err = iso7816_select_path (app->slot, path+1, pathlen-1);
+      err = iso7816_select_path (app->slot, path+1, pathlen-1, 0);
       if (err)
         {
           log_error ("p15: error selecting path ");
@@ -4104,7 +4104,7 @@ app_select_p15 (app_t app)
          Using the 2f02 just works. */
       unsigned short path[1] = { 0x2f00 };
 
-      rc = iso7816_select_path (slot, path, 1);
+      rc = iso7816_select_path (slot, path, 1, 0);
       if (!rc)
         {
           direct = 1;
@@ -4112,7 +4112,7 @@ app_select_p15 (app_t app)
           if (def_home_df)
             {
               path[0] = def_home_df;
-              rc = iso7816_select_path (slot, path, 1);
+              rc = iso7816_select_path (slot, path, 1, 0);
             }
         }
     }
diff --git a/scd/iso7816.c b/scd/iso7816.c
index 450590175..dcb2845c7 100644
--- a/scd/iso7816.c
+++ b/scd/iso7816.c
@@ -193,18 +193,26 @@ iso7816_select_file (int slot, int tag, int is_dir)
 }
 
 
-/* Do a select file command with a direct path. */
+/* Do a select file command with a direct path.  If TOPDF is set, the
+ * actual used path is 3f00/<topdf>/<path>.  */
 gpg_error_t
-iso7816_select_path (int slot, const unsigned short *path, size_t pathlen)
+iso7816_select_path (int slot, const unsigned short *path, size_t pathlen,
+                     unsigned short topdf)
 {
   int sw, p0, p1;
   unsigned char buffer[100];
-  int buflen;
+  int buflen = 0;
 
-  if (pathlen/2 >= sizeof buffer)
+  if (pathlen*2 + 2 >= sizeof buffer)
     return gpg_error (GPG_ERR_TOO_LARGE);
 
-  for (buflen = 0; pathlen; pathlen--, path++)
+  if (topdf)
+    {
+      buffer[buflen++] = topdf >> 8;
+      buffer[buflen++] = topdf;
+    }
+
+  for (; pathlen; pathlen--, path++)
     {
       buffer[buflen++] = (*path >> 8);
       buffer[buflen++] = *path;
diff --git a/scd/iso7816.h b/scd/iso7816.h
index 2cbfe6185..f7934bb5b 100644
--- a/scd/iso7816.h
+++ b/scd/iso7816.h
@@ -68,7 +68,8 @@ gpg_error_t iso7816_select_application_ext (int slot,
 gpg_error_t iso7816_select_mf (int slot);
 gpg_error_t iso7816_select_file (int slot, int tag, int is_dir);
 gpg_error_t iso7816_select_path (int slot,
-                                 const unsigned short *path, size_t pathlen);
+                                 const unsigned short *path, size_t pathlen,
+                                 unsigned short top_df);
 gpg_error_t iso7816_list_directory (int slot, int list_dirs,
                                     unsigned char **result, size_t *resultlen);
 gpg_error_t iso7816_apdu_direct (int slot,