/* findkey.c - locate the secret key
* Copyright (C) 2001 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <unistd.h>
#include <sys/stat.h>
#include <assert.h>
#include "agent.h"
/* Helper to pass data to the check callback of the unprotect function. */
struct try_unprotect_arg_s {
const unsigned char *protected_key;
unsigned char *unprotected_key;
};
int
agent_write_private_key (const unsigned char *grip,
const void *buffer, size_t length, int force)
{
int i;
char *fname;
FILE *fp;
char hexgrip[40+4+1];
for (i=0; i < 20; i++)
sprintf (hexgrip+2*i, "%02X", grip[i]);
strcpy (hexgrip+40, ".key");
fname = make_filename (opt.homedir, "private-keys-v1.d", hexgrip, NULL);
if (force)
fp = fopen (fname, "wb");
else
{
if (!access (fname, F_OK))
{
log_error ("secret key file `%s' already exists\n", fname);
xfree (fname);
return seterr (General_Error);
}
fp = fopen (fname, "wbx"); /* FIXME: the x is a GNU extension - let
configure check whether this actually
works */
}
if (!fp)
{
log_error ("can't create `%s': %s\n", fname, strerror (errno));
xfree (fname);
return seterr (File_Create_Error);
}
if (fwrite (buffer, length, 1, fp) != 1)
{
log_error ("error writing `%s': %s\n", fname, strerror (errno));
fclose (fp);
remove (fname);
xfree (fname);
return seterr (File_Create_Error);
}
if ( fclose (fp) )
{
log_error ("error closing `%s': %s\n", fname, strerror (errno));
remove (fname);
xfree (fname);
return seterr (File_Create_Error);
}
xfree (fname);
return 0;
}
/* Callback function to try the unprotection from the passpharse query
code. */
static int
try_unprotect_cb (struct pin_entry_info_s *pi)
{
struct try_unprotect_arg_s *arg = pi->check_cb_arg;
size_t dummy;
assert (!arg->unprotected_key);
return agent_unprotect (arg->protected_key, pi->pin,
&arg->unprotected_key, &dummy);
}
/* Unprotect the canconical encoded S-expression key in KEYBUF. GRIP
should be the hex encoded keygrip of that key to be used with the
cahing mechanism. */
static int
unprotect (unsigned char **keybuf, const unsigned char *grip)
{
struct pin_entry_info_s *pi;
struct try_unprotect_arg_s arg;
int rc, i;
unsigned char *result;
size_t resultlen;
char hexgrip[40+1];
for (i=0; i < 20; i++)
sprintf (hexgrip+2*i, "%02X", grip[i]);
hexgrip[40] = 0;
/* first try to get it from the cache - if there is none or we can't
unprotect it, we fall back to ask the user */
{
void *cache_marker;
const char *pw = agent_get_cache (hexgrip, &cache_marker);
if (pw)
{
rc = agent_unprotect (*keybuf, pw, &result, &resultlen);
agent_unlock_cache_entry (&cache_marker);
if (!rc)
{
xfree (*keybuf);
*keybuf = result;
return 0;
}
rc = 0;
}
}
pi = gcry_calloc_secure (1, sizeof (*pi) + 100);
pi->max_length = 100;
pi->min_digits = 0; /* we want a real passphrase */
pi->max_digits = 8;
pi->max_tries = 3;
pi->check_cb = try_unprotect_cb;
arg.protected_key = *keybuf;
arg.unprotected_key = NULL;
pi->check_cb_arg = &arg;
rc = agent_askpin (NULL, pi);
if (!rc)
{
assert (arg.unprotected_key);
agent_put_cache (hexgrip, pi->pin, 0);
xfree (*keybuf);
*keybuf = arg.unprotected_key;
}
xfree (pi);
return rc;
}
/* Return the secret key as an S-Exp after locating it using the grip.
Returns NULL if key is not available or the operation should be
diverted to a token. In the latter case shadow_info will point to
an allocated S-Expression with the shadow_info part from the
file. */
GCRY_SEXP
agent_key_from_file (const unsigned char *grip, unsigned char **shadow_info)
{
int i, rc;
char *fname;
FILE *fp;
struct stat st;
unsigned char *buf;
size_t len, buflen, erroff;
GCRY_SEXP s_skey;
char hexgrip[40+4+1];
if (shadow_info)
*shadow_info = NULL;
for (i=0; i < 20; i++)
sprintf (hexgrip+2*i, "%02X", grip[i]);
strcpy (hexgrip+40, ".key");
fname = make_filename (opt.homedir, "private-keys-v1.d", hexgrip, NULL);
fp = fopen (fname, "rb");
if (!fp)
{
log_error ("can't open `%s': %s\n", fname, strerror (errno));
xfree (fname);
return NULL;
}
if (fstat (fileno(fp), &st))
{
log_error ("can't stat `%s': %s\n", fname, strerror (errno));
xfree (fname);
fclose (fp);
return NULL;
}
buflen = st.st_size;
buf = xmalloc (buflen+1);
if (fread (buf, buflen, 1, fp) != 1)
{
log_error ("error reading `%s': %s\n", fname, strerror (errno));
xfree (fname);
fclose (fp);
xfree (buf);
return NULL;
}
rc = gcry_sexp_sscan (&s_skey, &erroff, buf, buflen);
xfree (fname);
fclose (fp);
xfree (buf);
if (rc)
{
log_error ("failed to build S-Exp (off=%u): %s\n",
(unsigned int)erroff, gcry_strerror (rc));
return NULL;
}
len = gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, NULL, 0);
assert (len);
buf = xtrymalloc (len);
if (!buf)
{
gcry_sexp_release (s_skey);
return NULL;
}
len = gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, buf, len);
assert (len);
gcry_sexp_release (s_skey);
switch (agent_private_key_type (buf))
{
case PRIVATE_KEY_CLEAR:
break; /* no unprotection needed */
case PRIVATE_KEY_PROTECTED:
rc = unprotect (&buf, grip);
if (rc)
log_error ("failed to unprotect the secret key: %s\n",
gnupg_strerror (rc));
break;
case PRIVATE_KEY_SHADOWED:
if (shadow_info)
{
const unsigned char *s;
size_t n;
rc = agent_get_shadow_info (buf, &s);
if (!rc)
{
n = gcry_sexp_canon_len (s, 0, NULL,NULL);
assert (n);
*shadow_info = xtrymalloc (n);
if (!*shadow_info)
rc = GNUPG_Out_Of_Core;
else
{
memcpy (*shadow_info, s, n);
rc = 0;
}
}
if (rc)
log_error ("get_shadow_info failed: %s\n", gnupg_strerror (rc));
}
rc = -1; /* ugly interface: we return an error but keep a value
in shadow_info. */
break;
default:
log_error ("invalid private key format\n");
rc = GNUPG_Bad_Secret_Key;
break;
}
if (rc)
{
xfree (buf);
return NULL;
}
/* arggg FIXME: does scan support secure memory? */
rc = gcry_sexp_sscan (&s_skey, &erroff,
buf, gcry_sexp_canon_len (buf, 0, NULL, NULL));
xfree (buf);
if (rc)
{
log_error ("failed to build S-Exp (off=%u): %s\n",
(unsigned int)erroff, gcry_strerror (rc));
return NULL;
}
return s_skey;
}
/* Return the secret key as an S-Exp after locating it using the grip.
Returns NULL if key is not available. 0 = key is available */
int
agent_key_available (const unsigned char *grip)
{
int i;
char *fname;
char hexgrip[40+4+1];
for (i=0; i < 20; i++)
sprintf (hexgrip+2*i, "%02X", grip[i]);
strcpy (hexgrip+40, ".key");
fname = make_filename (opt.homedir, "private-keys-v1.d", hexgrip, NULL);
i = !access (fname, R_OK)? 0 : -1;
xfree (fname);
return i;
}