/* Callback used to ask for the PIN which should be set into BUF. The
buf has been allocated by the caller and is of size MAXBUF which
includes the terminating null. The function should return an UTF-8
string with the passphrase, the buffer may optionally be padded
with arbitrary characters.
INFO gets displayed as part of a generic string. However if the
first character of INFO is a vertical bar all up to the next
verical bar are considered flags and only everything after the
second vertical bar gets displayed as the full prompt.
Flags:
'N' = New PIN, this requests a second prompt to repeat the
PIN. If the PIN is not correctly repeated it starts from
all over.
'A' = The PIN is an Admin PIN, SO-PIN or alike.
'P' = The PIN is a PUK (Personal Unblocking Key).
'R' = The PIN is a Reset Code.
Example:
"|AN|Please enter the new security officer's PIN"
The text "Please ..." will get displayed and the flags 'A' and 'N'
are considered.
*/
static int
getpin_cb (void *opaque, const char *info, char *buf, size_t maxbuf)
{
struct pin_entry_info_s *pi;
int rc;
ctrl_t ctrl = opaque;
const char *ends, *s;
int any_flags = 0;
int newpin = 0;
int resetcode = 0;
int is_puk = 0;
const char *again_text = NULL;
const char *prompt = "PIN";
if (buf && maxbuf < 2)
return gpg_error (GPG_ERR_INV_VALUE);
/* Parse the flags. */
if (info && *info =='|' && (ends=strchr (info+1, '|')))
{
for (s=info+1; s < ends; s++)
{
if (*s == 'A')
prompt = _("Admin PIN");
else if (*s == 'P')
{
/* TRANSLATORS: A PUK is the Personal Unblocking Code
used to unblock a PIN. */
prompt = _("PUK");
is_puk = 1;
}
else if (*s == 'N')
newpin = 1;
else if (*s == 'R')
{
prompt = _("Reset Code");
resetcode = 1;
}
}
info = ends+1;
any_flags = 1;
}
else if (info && *info == '|')
log_debug ("pin_cb called without proper PIN info hack\n");
/* If BUF has been passed as NULL, we are in pinpad mode: The
callback opens the popup and immediatley returns. */
if (!buf)
{
if (maxbuf == 0) /* Close the pinentry. */
{
agent_popup_message_stop (ctrl);
rc = 0;
}
else if (maxbuf == 1) /* Open the pinentry. */
{
if (info)
{
char *desc;
if ( asprintf (&desc,
_("%s%%0A%%0AUse the reader's pinpad for input."),
info) < 0 )
rc = gpg_error_from_syserror ();
else
{
rc = agent_popup_message_start (ctrl, desc, NULL);
xfree (desc);
}
}
else
rc = agent_popup_message_start (ctrl, NULL, NULL);
}
else
rc = gpg_error (GPG_ERR_INV_VALUE);
return rc;
}
/* FIXME: keep PI and TRIES in OPAQUE. Frankly this is a whole
mess because we should call the card's verify function from the
pinentry check pin CB. */
again:
pi = gcry_calloc_secure (1, sizeof (*pi) + maxbuf + 10);
if (!pi)
return gpg_error_from_syserror ();
pi->max_length = maxbuf-1;
pi->min_digits = 0; /* we want a real passphrase */
pi->max_digits = 16;
pi->max_tries = 3;
if (any_flags)
{
rc = agent_askpin (ctrl, info, prompt, again_text, pi, NULL, 0);
again_text = NULL;
if (!rc && newpin)
{
struct pin_entry_info_s *pi2;
pi2 = gcry_calloc_secure (1, sizeof (*pi) + maxbuf + 10);
if (!pi2)
{
rc = gpg_error_from_syserror ();
xfree (pi);
return rc;
}
pi2->max_length = maxbuf-1;
pi2->min_digits = 0;
pi2->max_digits = 16;
pi2->max_tries = 1;
rc = agent_askpin (ctrl,
(resetcode?
_("Repeat this Reset Code"):
is_puk?
_("Repeat this PUK"):
_("Repeat this PIN")),
prompt, NULL, pi2, NULL, 0);
if (!rc && strcmp (pi->pin, pi2->pin))
{
again_text = (resetcode?
N_("Reset Code not correctly repeated; try again"):
is_puk?
N_("PUK not correctly repeated; try again"):
N_("PIN not correctly repeated; try again"));
xfree (pi2);
xfree (pi);
goto again;
}
xfree (pi2);
}
}
else
{
char *desc;
if ( asprintf (&desc,
_("Please enter the PIN%s%s%s to unlock the card"),
info? " (`":"",
info? info:"",
info? "')":"") < 0)
desc = NULL;
rc = agent_askpin (ctrl, desc?desc:info, prompt, NULL, pi, NULL, 0);
xfree (desc);
}
if (!rc)
{
strncpy (buf, pi->pin, maxbuf-1);
buf[maxbuf-1] = 0;
}
xfree (pi);
return rc;
}
/* Unprotect the canconical encoded S-expression key in KEYBUF. GRIP
should be the hex encoded keygrip of that key to be used with the
caching mechanism. DESC_TEXT may be set to override the default
description used for the pinentry. If LOOKUP_TTL is given this
function is used to lookup the default ttl. */
static int
unprotect (ctrl_t ctrl, const char *desc_text,
unsigned char **keybuf, const unsigned char *grip,
cache_mode_t cache_mode, lookup_ttl_t lookup_ttl)
{
struct pin_entry_info_s *pi;
struct try_unprotect_arg_s arg;
int rc;
unsigned char *result;
size_t resultlen;
char hexgrip[40+1];
bin2hex (grip, 20, hexgrip);
/* 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 */
if (cache_mode != CACHE_MODE_IGNORE)
{
void *cache_marker;
const char *pw;
retry:
pw = agent_get_cache (hexgrip, cache_mode, &cache_marker);
if (pw)
{
rc = agent_unprotect (*keybuf, pw, NULL, &result, &resultlen);
agent_unlock_cache_entry (&cache_marker);
if (!rc)
{
xfree (*keybuf);
*keybuf = result;
return 0;
}
rc = 0;
}
/* If the pinentry is currently in use, we wait up to 60 seconds
for it to close and check the cache again. This solves a common
situation where several requests for unprotecting a key have
been made but the user is still entering the passphrase for
the first request. Because all requests to agent_askpin are
serialized they would then pop up one after the other to
request the passphrase - despite that the user has already
entered it and is then available in the cache. This
implementation is not race free but in the worst case the
user has to enter the passphrase only once more. */
if (pinentry_active_p (ctrl, 0))
{
/* Active - wait */
if (!pinentry_active_p (ctrl, 60))
{
/* We need to give the other thread a chance to actually put
it into the cache. */
pth_sleep (1);
goto retry;
}
/* Timeout - better call pinentry now the plain way. */
}
}
pi = gcry_calloc_secure (1, sizeof (*pi) + 100);
if (!pi)
return gpg_error_from_syserror ();
pi->max_length = 100;
pi->min_digits = 0; /* we want a real passphrase */
pi->max_digits = 16;
pi->max_tries = 3;
pi->check_cb = try_unprotect_cb;
arg.ctrl = ctrl;
arg.protected_key = *keybuf;
arg.unprotected_key = NULL;
arg.change_required = 0;
pi->check_cb_arg = &arg;
rc = agent_askpin (ctrl, desc_text, NULL, NULL, pi);
if (!rc)
{
assert (arg.unprotected_key);
if (arg.change_required)
{
size_t canlen, erroff;
gcry_sexp_t s_skey;
assert (arg.unprotected_key);
canlen = gcry_sexp_canon_len (arg.unprotected_key, 0, NULL, NULL);
rc = gcry_sexp_sscan (&s_skey, &erroff,
(char*)arg.unprotected_key, canlen);
if (rc)
{
log_error ("failed to build S-Exp (off=%u): %s\n",
(unsigned int)erroff, gpg_strerror (rc));
wipememory (arg.unprotected_key, canlen);
xfree (arg.unprotected_key);
xfree (pi);
return rc;
}
rc = agent_protect_and_store (ctrl, s_skey);
gcry_sexp_release (s_skey);
if (rc)
{
log_error ("changing the passphrase failed: %s\n",
gpg_strerror (rc));
wipememory (arg.unprotected_key, canlen);
xfree (arg.unprotected_key);
xfree (pi);
return rc;
}
}
else
agent_put_cache (hexgrip, cache_mode, pi->pin,
lookup_ttl? lookup_ttl (hexgrip) : 0);
xfree (*keybuf);
*keybuf = arg.unprotected_key;
}
xfree (pi);
return rc;
}
/* Unprotect the canconical encoded S-expression key in KEYBUF. GRIP
should be the hex encoded keygrip of that key to be used with the
caching mechanism. DESC_TEXT may be set to override the default
description used for the pinentry. If LOOKUP_TTL is given this
function is used to lookup the default ttl. If R_PASSPHRASE is not
NULL, the function succeeded and the key was protected the used
passphrase (entered or from the cache) is stored there; if not NULL
will be stored. The caller needs to free the returned
passphrase. */
static int
unprotect (ctrl_t ctrl, const char *cache_nonce, const char *desc_text,
unsigned char **keybuf, const unsigned char *grip,
cache_mode_t cache_mode, lookup_ttl_t lookup_ttl,
char **r_passphrase)
{
struct pin_entry_info_s *pi;
struct try_unprotect_arg_s arg;
int rc;
unsigned char *result;
size_t resultlen;
char hexgrip[40+1];
if (r_passphrase)
*r_passphrase = NULL;
bin2hex (grip, 20, hexgrip);
/* Initially try to get it using a cache nonce. */
if (cache_nonce)
{
char *pw;
pw = agent_get_cache (cache_nonce, CACHE_MODE_NONCE);
if (pw)
{
rc = agent_unprotect (ctrl, *keybuf, pw, NULL, &result, &resultlen);
if (!rc)
{
if (r_passphrase)
*r_passphrase = pw;
else
xfree (pw);
xfree (*keybuf);
*keybuf = result;
return 0;
}
xfree (pw);
}
}
/* 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 */
if (cache_mode != CACHE_MODE_IGNORE)
{
char *pw;
retry:
pw = agent_get_cache (hexgrip, cache_mode);
if (pw)
{
rc = agent_unprotect (ctrl, *keybuf, pw, NULL, &result, &resultlen);
if (!rc)
{
if (cache_mode == CACHE_MODE_NORMAL)
agent_store_cache_hit (hexgrip);
if (r_passphrase)
*r_passphrase = pw;
else
xfree (pw);
xfree (*keybuf);
*keybuf = result;
return 0;
}
xfree (pw);
rc = 0;
}
else if (cache_mode == CACHE_MODE_NORMAL)
{
/* The standard use of GPG keys is to have a signing and an
encryption subkey. Commonly both use the same
passphrase. We try to help the user to enter the
passphrase only once by silently trying the last
correctly entered passphrase. Checking one additional
passphrase should be acceptable; despite the S2K
introduced delays. The assumed workflow is:
1. Read encrypted message in a MUA and thus enter a
passphrase for the encryption subkey.
2. Reply to that mail with an encrypted and signed
mail, thus entering the passphrase for the signing
subkey.
We can often avoid the passphrase entry in the second
step. We do this only in normal mode, so not to
interfere with unrelated cache entries. */
pw = agent_get_cache (NULL, cache_mode);
if (pw)
{
rc = agent_unprotect (ctrl, *keybuf, pw, NULL,
&result, &resultlen);
if (!rc)
{
if (r_passphrase)
*r_passphrase = pw;
else
xfree (pw);
xfree (*keybuf);
*keybuf = result;
return 0;
}
xfree (pw);
rc = 0;
}
}
/* If the pinentry is currently in use, we wait up to 60 seconds
for it to close and check the cache again. This solves a common
situation where several requests for unprotecting a key have
been made but the user is still entering the passphrase for
the first request. Because all requests to agent_askpin are
serialized they would then pop up one after the other to
request the passphrase - despite that the user has already
entered it and is then available in the cache. This
implementation is not race free but in the worst case the
user has to enter the passphrase only once more. */
if (pinentry_active_p (ctrl, 0))
{
/* Active - wait */
if (!pinentry_active_p (ctrl, 60))
{
/* We need to give the other thread a chance to actually put
it into the cache. */
npth_sleep (1);
goto retry;
}
/* Timeout - better call pinentry now the plain way. */
}
}
pi = gcry_calloc_secure (1, sizeof (*pi) + MAX_PASSPHRASE_LEN + 1);
if (!pi)
return gpg_error_from_syserror ();
pi->max_length = MAX_PASSPHRASE_LEN + 1;
pi->min_digits = 0; /* we want a real passphrase */
pi->max_digits = 16;
pi->max_tries = 3;
pi->check_cb = try_unprotect_cb;
arg.ctrl = ctrl;
arg.protected_key = *keybuf;
arg.unprotected_key = NULL;
arg.change_required = 0;
pi->check_cb_arg = &arg;
rc = agent_askpin (ctrl, desc_text, NULL, NULL, pi, hexgrip, cache_mode);
if (!rc)
{
assert (arg.unprotected_key);
if (arg.change_required)
{
/* The callback told as that the user should change their
passphrase. Present the dialog to do. */
size_t canlen, erroff;
gcry_sexp_t s_skey;
assert (arg.unprotected_key);
canlen = gcry_sexp_canon_len (arg.unprotected_key, 0, NULL, NULL);
rc = gcry_sexp_sscan (&s_skey, &erroff,
(char*)arg.unprotected_key, canlen);
if (rc)
{
log_error ("failed to build S-Exp (off=%u): %s\n",
(unsigned int)erroff, gpg_strerror (rc));
wipememory (arg.unprotected_key, canlen);
xfree (arg.unprotected_key);
xfree (pi);
return rc;
}
rc = agent_protect_and_store (ctrl, s_skey, NULL);
gcry_sexp_release (s_skey);
if (rc)
{
log_error ("changing the passphrase failed: %s\n",
gpg_strerror (rc));
wipememory (arg.unprotected_key, canlen);
xfree (arg.unprotected_key);
xfree (pi);
return rc;
}
}
else
{
/* Passphrase is fine. */
agent_put_cache (hexgrip, cache_mode, pi->pin,
lookup_ttl? lookup_ttl (hexgrip) : 0);
agent_store_cache_hit (hexgrip);
if (r_passphrase && *pi->pin)
*r_passphrase = xtrystrdup (pi->pin);
}
xfree (*keybuf);
*keybuf = arg.unprotected_key;
}
xfree (pi);
return rc;
}
