scd: Disable pinpad if it's impossible by KDF DO.

* scd/app-openpgp.c (struct app_local_s): Add pinpad.disabled field.
(do_getattr): Set pinpad.disabled field.
(check_pinpad_request): Use the pinpad.disabled field.
(do_setattr): Update pinpad.disabled field.

--

GnuPG-bug-id: 4832
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
(cherry picked from commit 95c7498b76)
Signed-off-by: Werner Koch <wk@gnupg.org>

scd/app-openpgp.c

@@ -71,6 +71,9 @@
 #include "../common/openpgpdefs.h"
 
 
+#define KDF_DATA_LENGTH_MIN  90
+#define KDF_DATA_LENGTH_MAX 110
+
 /* A table describing the DOs of the card.  */
 static struct {
   int tag;
@@ -200,7 +203,7 @@ struct app_local_s {
     unsigned int private_dos:1;
     unsigned int algo_attr_change:1;   /* Algorithm attributes changeable.  */
     unsigned int has_decrypt:1;        /* Support symmetric decryption.     */
-    unsigned int kdf_do:1;                /* Support KDF DO.                */
+    unsigned int kdf_do:1;             /* Support KDF DO.                   */
 
     unsigned int sm_algo:2;            /* Symmetric crypto algo for SM.     */
     unsigned int pin_blk2:1;           /* PIN block 2 format supported.     */
@@ -220,6 +223,7 @@ struct app_local_s {
   /* Pinpad request specified on card.  */
   struct
   {
+    unsigned int disabled:1;    /* No pinpad use because of KDF DO.  */
     unsigned int specified:1;
     int fixedlen_user;
     int fixedlen_admin;
@@ -987,7 +991,7 @@ do_getattr (app_t app, ctrl_t ctrl, const char *name)
     { "$ENCRKEYID",   0x0000, -6 },
     { "$SIGNKEYID",   0x0000, -7 },
     { "$DISPSERIALNO",0x0000, -4 },
-    { "KDF",          0x00F9 },
+    { "KDF",          0x00F9, 5 },
     { NULL, 0 }
   };
   int idx, i, rc;
@@ -1112,11 +1116,25 @@ do_getattr (app_t app, ctrl_t ctrl, const char *name)
             for (i=0; i < 3; i++)
               send_fprtime_if_not_null (ctrl, table[idx].name, i+1, value+i*4);
         }
+      else if (table[idx].special == 5)
+        {
+          if ((valuelen == KDF_DATA_LENGTH_MIN
+               || valuelen == KDF_DATA_LENGTH_MAX)
+              && (value[2] == 0x03))
+            app->app_local->pinpad.disabled = 1;
+          else
+            app->app_local->pinpad.disabled = 0;
+        }
       else
         send_status_info (ctrl, table[idx].name, value, valuelen, NULL, 0);
 
       xfree (relptr);
     }
+  else
+    {
+      if (table[idx].special == 5)
+        app->app_local->pinpad.disabled = 0;
+    }
   return rc;
 }
 
@@ -1993,6 +2011,9 @@ do_readcert (app_t app, const char *certid,
 static int
 check_pinpad_request (app_t app, pininfo_t *pininfo, int admin_pin)
 {
+  if (app->app_local->pinpad.disabled)
+    return 1;
+
   if (app->app_local->pinpad.specified == 0) /* No preference on card.  */
     {
       if (pininfo->fixedlen == 0) /* Reader has varlen capability.  */
@@ -2087,9 +2108,6 @@ get_prompt_info (app_t app, int chvno, unsigned long sigcount, int remaining)
   return result;
 }
 
-#define KDF_DATA_LENGTH_MIN  90
-#define KDF_DATA_LENGTH_MAX 110
-
 /* Compute hash if KDF-DO is available.  CHVNO must be 0 for reset
    code, 1 or 2 for user pin and 3 for admin pin.
  */
@@ -2540,6 +2558,12 @@ do_setattr (app_t app, const char *name,
       app->did_chv1 = 0;
       app->did_chv2 = 0;
       app->did_chv3 = 0;
+
+      if ((valuelen == KDF_DATA_LENGTH_MIN || valuelen == KDF_DATA_LENGTH_MAX)
+          && (value[2] == 0x03))
+        app->app_local->pinpad.disabled = 1;
+      else
+        app->app_local->pinpad.disabled = 0;
     }
 
   return rc;
@@ -4259,7 +4283,6 @@ check_against_given_fingerprint (app_t app, const char *fpr, int key)
 }
 
 
-
 /* Compute a digital signature on INDATA which is expected to be the
    raw message digest. For this application the KEYIDSTR consists of
    the serialnumber and the fingerprint delimited by a slash.