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scd: First changes to implement a PIN cache.

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* scd/command.c (pincache_put): New.  Uses a dummy key for now.
(pincache_get): New.
* scd/app.c (select_application): Flush the PIN cache.
(scd_update_reader_status_file): Ditto.
(maybe_switch_app): Call the new prep_reselect function.
(app_write_learn_status): Ditto.
* scd/app-openpgp.c (cache_pin): New helper to cache a PIN.
(verify_chv2): Call it.
(verify_chv3): Call it.
(clear_chv_status): Call it.
(do_change_pin): Call it.

* scd/app-common.h (struct app_ctx_s): Add function 'prep_select'.
* scd/app-openpgp.c (do_prep_reselect): New stub function.
(app_select_openpgp): Set new stub function.
* scd/app-piv.c (do_prep_reselect): New stub function.
(app_select_piv): Set new stub function.

* scd/app-common.h (struct app_ctx_s): Add parameter ctrl to setattr,
sign, auth, decipher, and check_pin.  Change all implementations and
callers to pass such a parameter.
--

This is work in progress.

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2020-01-07 18:45:33 +01:00
parent d5c00354bb
commit fbf97a7856
No known key found for this signature in database
GPG key ID: E3FDFF218E45B72B
11 changed files with 418 additions and 85 deletions
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190
scd/command.c
View file

@ -42,7 +42,8 @@
#include "../common/asshelp.h"
#include "../common/server-help.h"
/* Maximum length allowed as a PIN; used for INQUIRE NEEDPIN */
/* Maximum length allowed as a PIN; used for INQUIRE NEEDPIN. That
* length needs to small compared to the maximum Assuan line length. */
#define MAXLEN_PIN 100
/* Maximum allowed size of key data as used in inquiries. */
@ -281,7 +282,7 @@ static const char hlp_serialno[] =
"selected and an error is returned if no such card available.\n"
"\n"
"If --all is given, all possible other applications of the card are\n"
"will also be selected for on-the-fly swicthing.\n"
"also selected to prepare for \"LEARN --force --multi\".\n"
"\n"
"If APPTYPE is given, an application of that type is selected and an\n"
"error is returned if the application is not supported or available.\n"
@ -2241,6 +2242,191 @@ send_status_printf (ctrl_t ctrl, const char *keyword, const char *format, ...)
}
/* Store the PIN in the PIN cache. The key to identify the PIN
* consists of (SLOT,APPNAME,PINREF). If PIN is NULL the PIN stored
* under the given key is cleared. If APPNAME and PINREF are NULL the
* entire PIN cache for SLOT is cleared. If SLOT is -1 the entire PIN
* cache is cleared. We do no use an scdaemon internal cache but let
* gpg-agent cache because it is better suited for this. */
void
pincache_put (ctrl_t ctrl, int slot, const char *appname, const char *pinref,
const char *pin)
{
gpg_error_t err;
assuan_context_t ctx;
char line[950];
gcry_cipher_hd_t cipherhd = NULL;
char *pinbuf = NULL;
unsigned char *wrappedkey = NULL;
size_t pinlen, pinbuflen, wrappedkeylen;
if (!ctrl)
{
/* No CTRL object provided. We could pick an arbitrary
* connection and send the status to that one. However, such a
* connection is inlikley to wait for a respinse from use and
* thus it would at best be read as a response to the next
* command send to us. That is not good because it may clog up
* our connection. Thus we better don't do that. A better will
* be to queue this up and let the agent poll for general status
* messages. */
/* struct server_local_s *sl; */
/* for (sl=session_list; sl; sl = sl->next_session) */
/* if (sl->ctrl_backlink && sl->ctrl_backlink->server_local */
/* && sl->ctrl_backlink->server_local->assuan_ctx) */
/* { */
/* ctrl = sl->ctrl_backlink; */
/* break; */
/* } */
}
if (!ctrl || !ctrl->server_local || !(ctx=ctrl->server_local->assuan_ctx))
return;
if (pin && !*pin)
return; /* Ignore an empty PIN. */
snprintf (line, sizeof line, "%d/%s/%s ",
slot, appname? appname:"-", pinref? pinref:"-");
/* Without an APPNAME etc or without a PIN we clear the cache and
* thus there is no need to send the pin - even if the caller
* accidentially passed a pin. */
if (pin && slot != -1 && appname && pinref)
{
pinlen = strlen (pin);
if ((pinlen % 8))
{
/* Pad with zeroes (AESWRAP requires multiples of 64 bit but
* at least 128 bit data). */
pinbuflen = pinlen + 8 - (pinlen % 8);
if (pinbuflen < 16)
pinbuflen = 16;
pinbuf = xtrycalloc_secure (1, pinbuflen);
if (!pinbuf)
{
err = gpg_error_from_syserror ();
goto leave;
}
memcpy (pinbuf, pin, pinlen);
pinlen = pinbuflen;
pin = pinbuf;
}
err = gcry_cipher_open (&cipherhd, GCRY_CIPHER_AES128,
GCRY_CIPHER_MODE_AESWRAP, 0);
if (!err)
err = gcry_cipher_setkey (cipherhd, "1234567890123456", 16);
if (err)
goto leave;
wrappedkeylen = pinlen + 8;
wrappedkey = xtrymalloc (wrappedkeylen);
if (!wrappedkey)
{
err = gpg_error_from_syserror ();
goto leave;
}
err = gcry_cipher_encrypt (cipherhd, wrappedkey, wrappedkeylen,
pin, pinlen);
if (err)
goto leave;
gcry_cipher_close (cipherhd);
cipherhd = NULL;
if (strlen (line) + 2*wrappedkeylen + 1 >= sizeof line)
{
log_error ("%s: PIN or pinref string too long - ignored", __func__);
goto leave;
}
bin2hex (wrappedkey, wrappedkeylen, line + strlen (line));
}
send_status_direct (ctrl, "PINCACHE_PUT", line);
leave:
xfree (pinbuf);
xfree (wrappedkey);
gcry_cipher_close (cipherhd);
if (err)
log_error ("%s: error caching PIN: %s\n", __func__, gpg_strerror (err));
}
/* Ask the agent for a cached PIN for the tuple (SLOT,APPNAME,PINREF).
* Returns on success and stores the PIN at R_PIN; the caller needs to
* wipe(!) and then free that value. On error NULL is stored at
* R_PIN and an error code returned. Common error codes are:
* GPG_ERR_NOT_SUPPORTED - Client does not support the PIN cache
* GPG_ERR_NO_DATA - No PIN cached for the given key tuple
*/
gpg_error_t
pincache_get (ctrl_t ctrl, int slot, const char *appname, const char *pinref,
char **r_pin)
{
gpg_error_t err;
assuan_context_t ctx;
char command[512];
unsigned char *value = NULL;
size_t valuelen;
unsigned char *wrappedkey = NULL;
size_t wrappedkeylen;
gcry_cipher_hd_t cipherhd = NULL;
if (slot == -1 || !appname || !pinref || !r_pin)
{
err = gpg_error (GPG_ERR_INV_ARG);
goto leave;
}
if (!ctrl || !ctrl->server_local || !(ctx = ctrl->server_local->assuan_ctx))
{
err = set_error (GPG_ERR_USE_CONDITIONS, "called w/o assuan context");
goto leave;
}
snprintf (command, sizeof command, "PINCACHE_GET %d/%s/%s",
slot, appname? appname:"-", pinref? pinref:"-");
err = assuan_inquire (ctx, command, &wrappedkey, &wrappedkeylen,
MAXLEN_PIN+24);
if (gpg_err_code (err) == GPG_ERR_ASS_CANCELED)
err = set_error (GPG_ERR_NOT_SUPPORTED,
"client does not feature a PIN cache");
else if (!err && (!wrappedkey || wrappedkeylen < 24))
err = set_error (GPG_ERR_INV_LENGTH, "received too short cryptogram");
else if (!err)
{
valuelen = wrappedkeylen - 8;
value = xtrymalloc_secure (valuelen);
if (!value)
{
err = gpg_error_from_syserror ();
goto leave;
}
err = gcry_cipher_open (&cipherhd, GCRY_CIPHER_AES128,
GCRY_CIPHER_MODE_AESWRAP, 0);
if (!err)
err = gcry_cipher_setkey (cipherhd, "1234567890123456", 16);
if (err)
goto leave;
err = gcry_cipher_decrypt (cipherhd, value, valuelen,
wrappedkey, wrappedkeylen);
if (err)
goto leave;
*r_pin = value;
value = NULL;
}
leave:
gcry_cipher_close (cipherhd);
xfree (wrappedkey);
xfree (value);
return err;
}
void
popup_prompt (void *opaque, int on)
{