/* Return the PK algorithm used by CERT as well as the length in bits
of the public key at NBITS. */
int
gpgsm_get_key_algo_info (ksba_cert_t cert, unsigned int *nbits)
{
gcry_sexp_t s_pkey;
int rc;
ksba_sexp_t p;
size_t n;
gcry_sexp_t l1, l2;
const char *name;
char namebuf[128];
if (nbits)
*nbits = 0;
p = ksba_cert_get_public_key (cert);
if (!p)
return 0;
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
xfree (p);
return 0;
}
rc = gcry_sexp_sscan (&s_pkey, NULL, (char *)p, n);
xfree (p);
if (rc)
return 0;
if (nbits)
*nbits = gcry_pk_get_nbits (s_pkey);
/* Breaking the algorithm out of the S-exp is a bit of a challenge ... */
l1 = gcry_sexp_find_token (s_pkey, "public-key", 0);
if (!l1)
{
gcry_sexp_release (s_pkey);
return 0;
}
l2 = gcry_sexp_cadr (l1);
gcry_sexp_release (l1);
l1 = l2;
name = gcry_sexp_nth_data (l1, 0, &n);
if (name)
{
if (n > sizeof namebuf -1)
n = sizeof namebuf -1;
memcpy (namebuf, name, n);
namebuf[n] = 0;
}
else
*namebuf = 0;
gcry_sexp_release (l1);
gcry_sexp_release (s_pkey);
return gcry_pk_map_name (namebuf);
}
static void
canon_len (void)
{
static struct {
size_t textlen; /* length of the buffer */
size_t expected;/* expected length or 0 on error and then ... */
size_t erroff; /* ... and at this offset */
gcry_error_t errcode; /* ... with this error code */
const char *text;
} values[] = {
{ 14, 13, 0, GPG_ERR_NO_ERROR, "(9:abcdefghi) " },
{ 16, 15, 0, GPG_ERR_NO_ERROR, "(10:abcdefghix)" },
{ 14, 0,14, GPG_ERR_SEXP_STRING_TOO_LONG, "(10:abcdefghi)" },
{ 15, 0, 1, GPG_ERR_SEXP_ZERO_PREFIX, "(010:abcdefghi)" },
{ 2, 0, 0, GPG_ERR_SEXP_NOT_CANONICAL, "1:"},
{ 4, 0, 4, GPG_ERR_SEXP_STRING_TOO_LONG, "(1:)"},
{ 5, 5, 0, GPG_ERR_NO_ERROR, "(1:x)"},
{ 2, 2, 0, GPG_ERR_NO_ERROR, "()"},
{ 4, 2, 0, GPG_ERR_NO_ERROR, "()()"},
{ 4, 4, 0, GPG_ERR_NO_ERROR, "(())"},
{ 3, 0, 3, GPG_ERR_SEXP_STRING_TOO_LONG, "(()"},
{ 3, 0, 1, GPG_ERR_SEXP_BAD_CHARACTER, "( )"},
{ 9, 9, 0, GPG_ERR_NO_ERROR, "(3:abc())"},
{ 10, 0, 6, GPG_ERR_SEXP_BAD_CHARACTER, "(3:abc ())"},
/* fixme: we need much more cases */
{ 0 },
};
int idx;
gcry_error_t errcode;
size_t n, erroff;
info ("checking canoncial length test function\n");
for (idx=0; values[idx].text; idx++)
{
n = gcry_sexp_canon_len ((const unsigned char*)values[idx].text,
values[idx].textlen,
&erroff, &errcode);
if (n && n == values[idx].expected)
; /* success */
else if (!n && !values[idx].expected)
{ /* we expected an error - check that this is the right one */
if (values[idx].erroff != erroff)
fail ("canonical length test %d - wrong error offset %u\n",
idx, (unsigned int)erroff);
if (gcry_err_code (errcode) != values[idx].errcode)
fail ("canonical length test %d - wrong error code %d\n",
idx, errcode);
}
else
fail ("canonical length test %d failed - n=%u, off=%u, err=%d\n",
idx, (unsigned int)n, (unsigned int)erroff, errcode);
}
}
/* Encrypt the DEK under the key contained in CERT and return it as a
canonical S-Exp in encval. */
static int
encrypt_dek (const DEK dek, ksba_cert_t cert, unsigned char **encval)
{
gcry_sexp_t s_ciph, s_data, s_pkey;
int rc;
ksba_sexp_t buf;
size_t len;
*encval = NULL;
/* get the key from the cert */
buf = ksba_cert_get_public_key (cert);
if (!buf)
{
log_error ("no public key for recipient\n");
return gpg_error (GPG_ERR_NO_PUBKEY);
}
len = gcry_sexp_canon_len (buf, 0, NULL, NULL);
if (!len)
{
log_error ("libksba did not return a proper S-Exp\n");
return gpg_error (GPG_ERR_BUG);
}
rc = gcry_sexp_sscan (&s_pkey, NULL, (char*)buf, len);
xfree (buf); buf = NULL;
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
return rc;
}
/* Put the encoded cleartext into a simple list. */
s_data = NULL; /* (avoid compiler warning) */
rc = encode_session_key (dek, &s_data);
if (rc)
{
log_error ("encode_session_key failed: %s\n", gpg_strerror (rc));
return rc;
}
/* pass it to libgcrypt */
rc = gcry_pk_encrypt (&s_ciph, s_data, s_pkey);
gcry_sexp_release (s_data);
gcry_sexp_release (s_pkey);
/* Reformat it. */
if (!rc)
{
rc = make_canon_sexp (s_ciph, encval, NULL);
gcry_sexp_release (s_ciph);
}
return rc;
}
/* This is a variant of gpgsm_print_name sending it output to an estream. */
void
gpgsm_es_print_name2 (estream_t fp, const char *name, int translate)
{
const unsigned char *s = (const unsigned char *)name;
int i;
if (!s)
{
es_fputs (_("[Error - No name]"), fp);
}
else if (*s == '<')
{
const char *s2 = strchr ( (char*)s+1, '>');
if (s2)
{
if (translate)
es_write_sanitized_utf8_buffer (fp, s + 1, s2 - (char*)s - 1,
NULL, NULL);
else
es_write_sanitized (fp, s + 1, s2 - (char*)s - 1, NULL, NULL);
}
}
else if (*s == '(')
{
pretty_es_print_sexp (fp, s, gcry_sexp_canon_len (s, 0, NULL, NULL));
}
else if (!((*s >= '0' && *s < '9')
|| (*s >= 'A' && *s <= 'Z')
|| (*s >= 'a' && *s <= 'z')))
es_fputs (_("[Error - invalid encoding]"), fp);
else
{
struct dn_array_s *dn = parse_dn (s);
if (!dn)
es_fputs (_("[Error - invalid DN]"), fp);
else
{
print_dn_parts (NULL, fp, dn, translate);
for (i=0; dn[i].key; i++)
{
xfree (dn[i].key);
xfree (dn[i].value);
}
xfree (dn);
}
}
}
/* Create a new S-expression object by reading LENGTH bytes from
BUFFER, assuming it is canonilized encoded or autodetected encoding
when AUTODETECT is set to 1. With FREEFNC not NULL, ownership of
the buffer is transferred to tyhe newle created object. FREEFNC
should be the freefnc used to release BUFFER; there is no guarantee
at which point this function is called; most likey you want to use
free() or gcry_free().
Passing LENGTH and AUTODETECT as 0 is allowed to indicate that
BUFFER points to a valid canonical encoded S-expression. A LENGTH
of 0 and AUTODETECT 1 indicates that buffer points to a
null-terminated string.
This function returns 0 and and the pointer to the new object in
RETSEXP or an error code in which case RETSEXP is set to NULL. */
gcry_error_t
gcry_sexp_create (gcry_sexp_t *retsexp, void *buffer, size_t length,
int autodetect, void (*freefnc)(void*) )
{
gcry_error_t errcode;
gcry_sexp_t se;
volatile va_list dummy_arg_ptr;
if (!retsexp)
return gcry_error (GPG_ERR_INV_ARG);
*retsexp = NULL;
if (autodetect < 0 || autodetect > 1 || !buffer)
return gcry_error (GPG_ERR_INV_ARG);
if (!length && !autodetect)
{ /* What a brave caller to assume that there is really a canonical
encoded S-expression in buffer */
length = gcry_sexp_canon_len (buffer, 0, NULL, &errcode);
if (!length)
return errcode;
}
else if (!length && autodetect)
{ /* buffer is a string */
length = strlen ((char *)buffer);
}
errcode = sexp_sscan (&se, NULL, buffer, length, 0, dummy_arg_ptr, NULL);
if (errcode)
return errcode;
*retsexp = se;
if (freefnc)
{
/* For now we release the buffer immediately. As soon as we
have changed the internal represenation of S-expression to
the canoncial format - which has the advantage of faster
parsing - we will use this function as a closure in our
GCRYSEXP object and use the BUFFER directly */
freefnc (buffer);
}
return gcry_error (GPG_ERR_NO_ERROR);
}
/* Convert a canonical encoded S-expression in CANON into the GCRY
type. */
gpg_error_t
canon_sexp_to_gcry (const unsigned char *canon, gcry_sexp_t *r_sexp)
{
gpg_error_t err;
size_t n;
gcry_sexp_t sexp;
*r_sexp = NULL;
n = gcry_sexp_canon_len (canon, 0, NULL, NULL);
if (!n)
{
log_error (_("invalid canonical S-expression found\n"));
err = gpg_error (GPG_ERR_INV_SEXP);
}
else if ((err = gcry_sexp_sscan (&sexp, NULL, canon, n)))
log_error (_("converting S-expression failed: %s\n"), gcry_strerror (err));
else
*r_sexp = sexp;
return err;
}
/* Return the so called KEYGRIP which is the SHA-1 hash of the public
key parameters expressed as an canoncial encoded S-Exp. ARRAY must
be 20 bytes long. Returns ARRAY or a newly allocated buffer if ARRAY was
given as NULL. May return NULL on error. */
unsigned char *
gpgsm_get_keygrip (ksba_cert_t cert, unsigned char *array)
{
gcry_sexp_t s_pkey;
int rc;
ksba_sexp_t p;
size_t n;
p = ksba_cert_get_public_key (cert);
if (!p)
return NULL; /* oops */
if (DBG_X509)
log_debug ("get_keygrip for public key\n");
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
return NULL;
}
rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
xfree (p);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
return NULL;
}
array = gcry_pk_get_keygrip (s_pkey, array);
gcry_sexp_release (s_pkey);
if (!array)
{
rc = gpg_error (GPG_ERR_GENERAL);
log_error ("can't calculate keygrip\n");
return NULL;
}
if (DBG_X509)
log_printhex ("keygrip=", array, 20);
return array;
}
/* Read a key with ID and return it in an allocate buffer pointed to
by r_BUF as a valid S-expression. */
int
agent_card_readkey (ctrl_t ctrl, const char *id, unsigned char **r_buf)
{
int rc;
char line[ASSUAN_LINELENGTH];
membuf_t data;
size_t len, buflen;
*r_buf = NULL;
rc = start_scd (ctrl);
if (rc)
return rc;
init_membuf (&data, 1024);
snprintf (line, DIM(line)-1, "READKEY %s", id);
line[DIM(line)-1] = 0;
rc = assuan_transact (ctrl->scd_local->ctx, line,
membuf_data_cb, &data,
NULL, NULL,
NULL, NULL);
if (rc)
{
xfree (get_membuf (&data, &len));
return unlock_scd (ctrl, rc);
}
*r_buf = get_membuf (&data, &buflen);
if (!*r_buf)
return unlock_scd (ctrl, gpg_error (GPG_ERR_ENOMEM));
if (!gcry_sexp_canon_len (*r_buf, buflen, NULL, NULL))
{
xfree (*r_buf); *r_buf = NULL;
return unlock_scd (ctrl, gpg_error (GPG_ERR_INV_VALUE));
}
return unlock_scd (ctrl, 0);
}
/* Get the keygrip from CERT, return 0 on success */
int
card_help_get_keygrip (ksba_cert_t cert, unsigned char *array)
{
gcry_sexp_t s_pkey;
int rc;
ksba_sexp_t p;
size_t n;
p = ksba_cert_get_public_key (cert);
if (!p)
return -1; /* oops */
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
return -1; /* libksba did not return a proper S-expression */
rc = gcry_sexp_sscan ( &s_pkey, NULL, p, n);
xfree (p);
if (rc)
return -1; /* can't parse that S-expression */
array = gcry_pk_get_keygrip (s_pkey, array);
gcry_sexp_release (s_pkey);
if (!array)
return -1; /* failed to calculate the keygrip */
return 0;
}
int
gpgsm_check_cms_signature (ksba_cert_t cert, ksba_const_sexp_t sigval,
gcry_md_hd_t md, int mdalgo, int *r_pkalgo)
{
int rc;
ksba_sexp_t p;
gcry_mpi_t frame;
gcry_sexp_t s_sig, s_hash, s_pkey;
size_t n;
int pkalgo;
if (r_pkalgo)
*r_pkalgo = 0;
n = gcry_sexp_canon_len (sigval, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
return gpg_error (GPG_ERR_BUG);
}
rc = gcry_sexp_sscan (&s_sig, NULL, (char*)sigval, n);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
return rc;
}
p = ksba_cert_get_public_key (cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
ksba_free (p);
gcry_sexp_release (s_sig);
return gpg_error (GPG_ERR_BUG);
}
if (DBG_CRYPTO)
log_printhex ("public key: ", p, n);
rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
ksba_free (p);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
gcry_sexp_release (s_sig);
return rc;
}
pkalgo = pk_algo_from_sexp (s_pkey);
if (r_pkalgo)
*r_pkalgo = pkalgo;
rc = do_encode_md (md, mdalgo, pkalgo,
gcry_pk_get_nbits (s_pkey), s_pkey, &frame);
if (rc)
{
gcry_sexp_release (s_sig);
gcry_sexp_release (s_pkey);
return rc;
}
/* put hash into the S-Exp s_hash */
if ( gcry_sexp_build (&s_hash, NULL, "%m", frame) )
BUG ();
gcry_mpi_release (frame);
rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (DBG_X509)
log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
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;
}
/* Return the information about the secret key specified by the binary
keygrip GRIP. If the key is a shadowed one the shadow information
will be stored at the address R_SHADOW_INFO as an allocated
S-expression. */
gpg_error_t
agent_key_info_from_file (ctrl_t ctrl, const unsigned char *grip,
int *r_keytype, unsigned char **r_shadow_info)
{
gpg_error_t err;
unsigned char *buf;
size_t len;
int keytype;
(void)ctrl;
if (r_keytype)
*r_keytype = PRIVATE_KEY_UNKNOWN;
if (r_shadow_info)
*r_shadow_info = NULL;
{
gcry_sexp_t sexp;
err = read_key_file (grip, &sexp);
if (err)
{
if (gpg_err_code (err) == GPG_ERR_ENOENT)
return gpg_error (GPG_ERR_NOT_FOUND);
else
return err;
}
err = make_canon_sexp (sexp, &buf, &len);
gcry_sexp_release (sexp);
if (err)
return err;
}
keytype = agent_private_key_type (buf);
switch (keytype)
{
case PRIVATE_KEY_CLEAR:
break;
case PRIVATE_KEY_PROTECTED:
/* If we ever require it we could retrieve the comment fields
from such a key. */
break;
case PRIVATE_KEY_SHADOWED:
if (r_shadow_info)
{
const unsigned char *s;
size_t n;
err = agent_get_shadow_info (buf, &s);
if (!err)
{
n = gcry_sexp_canon_len (s, 0, NULL, NULL);
assert (n);
*r_shadow_info = xtrymalloc (n);
if (!*r_shadow_info)
err = gpg_error_from_syserror ();
else
memcpy (*r_shadow_info, s, n);
}
}
break;
default:
err = gpg_error (GPG_ERR_BAD_SECKEY);
break;
}
if (!err && r_keytype)
*r_keytype = keytype;
xfree (buf);
return err;
}
/* Return the secret key as an S-Exp in RESULT after locating it using
the GRIP. Stores NULL at RESULT if the operation shall be diverted
to a token; in this case an allocated S-expression with the
shadow_info part from the file is stored at SHADOW_INFO.
CACHE_MODE defines now the cache shall be used. DESC_TEXT may be
set to present a custom description for the pinentry. LOOKUP_TTL
is an optional function to convey a TTL to the cache manager; we do
not simply pass the TTL value because the value is only needed if an
unprotect action was needed and looking up the TTL may have some
overhead (e.g. scanning the sshcontrol file). */
gpg_error_t
agent_key_from_file (ctrl_t ctrl, const char *desc_text,
const unsigned char *grip, unsigned char **shadow_info,
cache_mode_t cache_mode, lookup_ttl_t lookup_ttl,
gcry_sexp_t *result)
{
int rc;
unsigned char *buf;
size_t len, buflen, erroff;
gcry_sexp_t s_skey;
int got_shadow_info = 0;
*result = NULL;
if (shadow_info)
*shadow_info = NULL;
rc = read_key_file (grip, &s_skey);
if (rc)
return rc;
/* For use with the protection functions we also need the key as an
canonical encoded S-expression in a buffer. Create this buffer
now. */
rc = make_canon_sexp (s_skey, &buf, &len);
if (rc)
return rc;
switch (agent_private_key_type (buf))
{
case PRIVATE_KEY_CLEAR:
break; /* no unprotection needed */
case PRIVATE_KEY_PROTECTED:
{
char *desc_text_final;
char *comment = NULL;
/* Note, that we will take the comment as a C string for
display purposes; i.e. all stuff beyond a Nul character is
ignored. */
{
gcry_sexp_t comment_sexp;
comment_sexp = gcry_sexp_find_token (s_skey, "comment", 0);
if (comment_sexp)
comment = gcry_sexp_nth_string (comment_sexp, 1);
gcry_sexp_release (comment_sexp);
}
desc_text_final = NULL;
if (desc_text)
rc = modify_description (desc_text, comment? comment:"", s_skey,
&desc_text_final);
gcry_free (comment);
if (!rc)
{
rc = unprotect (ctrl, desc_text_final, &buf, grip,
cache_mode, lookup_ttl);
if (rc)
log_error ("failed to unprotect the secret key: %s\n",
gpg_strerror (rc));
}
xfree (desc_text_final);
}
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 = out_of_core ();
else
{
memcpy (*shadow_info, s, n);
rc = 0;
got_shadow_info = 1;
}
}
if (rc)
log_error ("get_shadow_info failed: %s\n", gpg_strerror (rc));
}
else
rc = gpg_error (GPG_ERR_UNUSABLE_SECKEY);
break;
default:
log_error ("invalid private key format\n");
rc = gpg_error (GPG_ERR_BAD_SECKEY);
break;
}
gcry_sexp_release (s_skey);
s_skey = NULL;
if (rc || got_shadow_info)
{
xfree (buf);
return rc;
}
buflen = gcry_sexp_canon_len (buf, 0, NULL, NULL);
rc = gcry_sexp_sscan (&s_skey, &erroff, (char*)buf, buflen);
wipememory (buf, buflen);
xfree (buf);
if (rc)
{
log_error ("failed to build S-Exp (off=%u): %s\n",
(unsigned int)erroff, gpg_strerror (rc));
return rc;
}
*result = s_skey;
return 0;
}
/* 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;
}
/* Check the signature on CERT using the ISSUER-CERT. This function
does only test the cryptographic signature and nothing else. It is
assumed that the ISSUER_CERT is valid. */
int
gpgsm_check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
{
const char *algoid;
gcry_md_hd_t md;
int rc, algo;
gcry_mpi_t frame;
ksba_sexp_t p;
size_t n;
gcry_sexp_t s_sig, s_hash, s_pkey;
algo = gcry_md_map_name ( (algoid=ksba_cert_get_digest_algo (cert)));
if (!algo)
{
log_error ("unknown hash algorithm '%s'\n", algoid? algoid:"?");
if (algoid
&& ( !strcmp (algoid, "1.2.840.113549.1.1.2")
||!strcmp (algoid, "1.2.840.113549.2.2")))
log_info (_("(this is the MD2 algorithm)\n"));
return gpg_error (GPG_ERR_GENERAL);
}
rc = gcry_md_open (&md, algo, 0);
if (rc)
{
log_error ("md_open failed: %s\n", gpg_strerror (rc));
return rc;
}
if (DBG_HASHING)
gcry_md_debug (md, "hash.cert");
rc = ksba_cert_hash (cert, 1, HASH_FNC, md);
if (rc)
{
log_error ("ksba_cert_hash failed: %s\n", gpg_strerror (rc));
gcry_md_close (md);
return rc;
}
gcry_md_final (md);
p = ksba_cert_get_sig_val (cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
return gpg_error (GPG_ERR_BUG);
}
if (DBG_CRYPTO)
{
int j;
log_debug ("signature value:");
for (j=0; j < n; j++)
log_printf (" %02X", p[j]);
log_printf ("\n");
}
rc = gcry_sexp_sscan ( &s_sig, NULL, (char*)p, n);
ksba_free (p);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
gcry_md_close (md);
return rc;
}
p = ksba_cert_get_public_key (issuer_cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
gcry_sexp_release (s_sig);
return gpg_error (GPG_ERR_BUG);
}
rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
ksba_free (p);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
gcry_md_close (md);
gcry_sexp_release (s_sig);
return rc;
}
rc = do_encode_md (md, algo, pk_algo_from_sexp (s_pkey),
gcry_pk_get_nbits (s_pkey), s_pkey, &frame);
if (rc)
{
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_pkey);
return rc;
}
/* put hash into the S-Exp s_hash */
if ( gcry_sexp_build (&s_hash, NULL, "%m", frame) )
BUG ();
gcry_mpi_release (frame);
rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (DBG_X509)
log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
return rc;
}
/** Read key given cert id in line. */
gpg_error_t cmd_readkey (assuan_context_t ctx, char *line)
{
gpg_err_code_t error = GPG_ERR_GENERAL;
pkcs11h_certificate_id_t cert_id = NULL;
gcry_sexp_t sexp = NULL;
unsigned char *blob = NULL;
size_t blob_size;
if (
(error = _get_certificate_by_name (
ctx,
line,
0,
&cert_id,
NULL
)) != GPG_ERR_NO_ERROR ||
(error = get_cert_sexp (ctx, cert_id, &sexp)) != GPG_ERR_NO_ERROR
) {
goto cleanup;
}
if ((blob_size = gcry_sexp_sprint (sexp, GCRYSEXP_FMT_CANON, NULL, 0)) == 0) {
error = GPG_ERR_BAD_KEY;
goto cleanup;
}
if ((blob = (unsigned char *)malloc (blob_size)) == NULL) {
error = GPG_ERR_ENOMEM;
goto cleanup;
}
if (gcry_sexp_sprint (sexp, GCRYSEXP_FMT_CANON, blob, blob_size) == 0) {
error = GPG_ERR_BAD_KEY;
goto cleanup;
}
if (
(error = assuan_send_data(
ctx,
blob,
gcry_sexp_canon_len (blob, 0, NULL, NULL)
)) != GPG_ERR_NO_ERROR
) {
goto cleanup;
}
error = GPG_ERR_NO_ERROR;
cleanup:
if (sexp != NULL) {
gcry_sexp_release(sexp);
sexp = NULL;
}
if (cert_id != NULL) {
pkcs11h_certificate_freeCertificateId (cert_id);
cert_id = NULL;
}
if (blob != NULL) {
free (blob);
blob = NULL;
}
return gpg_error (error);
}
/* Check the signature on CERT using the ISSUER_CERT. This function
does only test the cryptographic signature and nothing else. It is
assumed that the ISSUER_CERT is valid. */
static gpg_error_t
check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
{
gpg_error_t err;
const char *algoid;
gcry_md_hd_t md;
int i, algo;
ksba_sexp_t p;
size_t n;
gcry_sexp_t s_sig, s_hash, s_pkey;
const char *s;
char algo_name[16+1]; /* hash algorithm name converted to lower case. */
int digestlen;
unsigned char *digest;
/* Hash the target certificate using the algorithm from that certificate. */
algoid = ksba_cert_get_digest_algo (cert);
algo = gcry_md_map_name (algoid);
if (!algo)
{
log_error (_("unknown hash algorithm '%s'\n"), algoid? algoid:"?");
return gpg_error (GPG_ERR_GENERAL);
}
s = gcry_md_algo_name (algo);
for (i=0; *s && i < sizeof algo_name - 1; s++, i++)
algo_name[i] = tolower (*s);
algo_name[i] = 0;
err = gcry_md_open (&md, algo, 0);
if (err)
{
log_error ("md_open failed: %s\n", gpg_strerror (err));
return err;
}
if (DBG_HASHING)
gcry_md_debug (md, "hash.cert");
err = ksba_cert_hash (cert, 1, HASH_FNC, md);
if (err)
{
log_error ("ksba_cert_hash failed: %s\n", gpg_strerror (err));
gcry_md_close (md);
return err;
}
gcry_md_final (md);
/* Get the signature value out of the target certificate. */
p = ksba_cert_get_sig_val (cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
return gpg_error (GPG_ERR_BUG);
}
if (DBG_CRYPTO)
{
int j;
log_debug ("signature value:");
for (j=0; j < n; j++)
log_printf (" %02X", p[j]);
log_printf ("\n");
}
err = gcry_sexp_sscan ( &s_sig, NULL, p, n);
ksba_free (p);
if (err)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (err));
gcry_md_close (md);
return err;
}
/* Get the public key from the issuer certificate. */
p = ksba_cert_get_public_key (issuer_cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
gcry_sexp_release (s_sig);
return gpg_error (GPG_ERR_BUG);
}
err = gcry_sexp_sscan ( &s_pkey, NULL, p, n);
ksba_free (p);
if (err)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (err));
gcry_md_close (md);
gcry_sexp_release (s_sig);
return err;
}
/* Prepare the values for signature verification. At this point we
have these values:
S_PKEY - S-expression with the issuer's public key.
S_SIG - Signature value as given in the certrificate.
MD - Finalized hash context with hash of the certificate.
ALGO_NAME - Lowercase hash algorithm name
*/
digestlen = gcry_md_get_algo_dlen (algo);
digest = gcry_md_read (md, algo);
if (pk_algo_from_sexp (s_pkey) == GCRY_PK_DSA)
{
if (digestlen != 20)
{
log_error (_("DSA requires the use of a 160 bit hash algorithm\n"));
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_pkey);
return gpg_error (GPG_ERR_INTERNAL);
}
if ( gcry_sexp_build (&s_hash, NULL, "(data(flags raw)(value %b))",
(int)digestlen, digest) )
BUG ();
}
else /* Not DSA. */
{
if ( gcry_sexp_build (&s_hash, NULL, "(data(flags pkcs1)(hash %s %b))",
algo_name, (int)digestlen, digest) )
BUG ();
}
err = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (DBG_X509)
log_debug ("gcry_pk_verify: %s\n", gpg_strerror (err));
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
return err;
}
/* Return true if the key in BLOB matches the 20 bytes keygrip GRIP.
We don't have the keygrips as meta data, thus we need to parse the
certificate. Fixme: We might want to return proper error codes
instead of failing a search for invalid certificates etc. */
static int
blob_x509_has_grip (KEYBOXBLOB blob, const unsigned char *grip)
{
int rc;
const unsigned char *buffer;
size_t length;
size_t cert_off, cert_len;
ksba_reader_t reader = NULL;
ksba_cert_t cert = NULL;
ksba_sexp_t p = NULL;
gcry_sexp_t s_pkey;
unsigned char array[20];
unsigned char *rcp;
size_t n;
buffer = _keybox_get_blob_image (blob, &length);
if (length < 40)
return 0; /* Too short. */
cert_off = get32 (buffer+8);
cert_len = get32 (buffer+12);
if (cert_off+cert_len > length)
return 0; /* Too short. */
rc = ksba_reader_new (&reader);
if (rc)
return 0; /* Problem with ksba. */
rc = ksba_reader_set_mem (reader, buffer+cert_off, cert_len);
if (rc)
goto failed;
rc = ksba_cert_new (&cert);
if (rc)
goto failed;
rc = ksba_cert_read_der (cert, reader);
if (rc)
goto failed;
p = ksba_cert_get_public_key (cert);
if (!p)
goto failed;
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
goto failed;
rc = gcry_sexp_sscan (&s_pkey, NULL, (char*)p, n);
if (rc)
{
gcry_sexp_release (s_pkey);
goto failed;
}
rcp = gcry_pk_get_keygrip (s_pkey, array);
gcry_sexp_release (s_pkey);
if (!rcp)
goto failed; /* Can't calculate keygrip. */
xfree (p);
ksba_cert_release (cert);
ksba_reader_release (reader);
return !memcmp (array, grip, 20);
failed:
xfree (p);
ksba_cert_release (cert);
ksba_reader_release (reader);
return 0;
}
