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agent: Add new shadow key type and functions to call tpm2daemon

Browse Source 
* agent/call-tpm2d.c: New.
* divert-tpm2.c: New.
* agent/Makefile.am: Add new files.
* agent/agent.h (DAEMON_TPM2D): New.  Add stub fucntions.
* agent/call-daemon.c (GNUPG_MODULE_NAME_TPM2DAEMON): New.
* agent/command.c (do_one_keyinfo): Handle tpmv2.
* agent/gpg-agent.c (oTpm2daemonProgram): New.
(opts): New option --tpm2daemon-program.
(parse_rereadable_options): Handle option.
* agent/pkdecrypt.c (agent_pkdecrypt): Divert to tpm2d.
(agent_pksign_do): Ditto.
---

A new shadow key type: "tpm2-v1" is introduced signalling that the
shadowed key is handled by the tpm2daemon.  A function to identify
this type is introduced and diversions to the tpm2daemon functions are
conditioned on this function for pkign and pkdecrypt where the same
diversions to scd are currently done.  The (info) field of the
shadowed key stores the actual TPM key.  The TPM key is encrypted so
only the physical TPM it was created on can read it (so no special
protection is required for the info filed), but if the (info) field
becomes corrupt or damaged, the key will be lost (unlike the token
case, where the key is actually moved inside the token).

Note, this commit adds handling for existing TPM format shadow keys,
but there is still no way to create them.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

Additional changes:
* Add ChangeLog entries.
* Some minor indentation fixes.
* agent/Makefile.am (gpg_agent_SOURCES): Change to make distcheck
  work.
* agent/agent.h [!HAVE_LIBTSS]: Do not return -EINVAL but an
  gpg_error_t.  Mark args as unused.
* agent/protect.c (agent_is_tpm2_key): Free BUF.

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
James Bottomley 2021-03-09 13:50:29 -08:00 committed by Werner Koch
parent 62a7854816
commit 1f995b9ba4
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
11 changed files with 519 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
agent/Makefile.am
View File

@ -38,6 +38,12 @@ endif
AM_CFLAGS = $(LIBGCRYPT_CFLAGS) $(GPG_ERROR_CFLAGS)
if HAVE_LIBTSS
tpm2_sources = divert-tpm2.c call-tpm2d.c
else
tpm2_sources =
endif
gpg_agent_SOURCES = \
gpg-agent.c agent.h \
command.c command-ssh.c \
@ -55,6 +61,7 @@ gpg_agent_SOURCES = \
cvt-openpgp.c cvt-openpgp.h \
call-scd.c \
call-daemon.c \
$(tpm2_sources) \
learncard.c
common_libs = $(libcommon)

58
agent/agent.h
View File

@ -59,6 +59,7 @@
enum daemon_type
{
DAEMON_SCD,
DAEMON_TPM2D,
DAEMON_MAX_TYPE
};
@ -459,6 +460,7 @@ gpg_error_t agent_public_key_from_file (ctrl_t ctrl,
const unsigned char *grip,
gcry_sexp_t *result);
int agent_pk_get_algo (gcry_sexp_t s_key);
int agent_is_tpm2_key(gcry_sexp_t s_key);
int agent_key_available (const unsigned char *grip);
gpg_error_t agent_key_info_from_file (ctrl_t ctrl, const unsigned char *grip,
int *r_keytype,
@ -577,6 +579,52 @@ gpg_error_t agent_marktrusted (ctrl_t ctrl, const char *name,
const char *fpr, int flag);
void agent_reload_trustlist (void);
/*-- divert-tpm2.c --*/
#ifdef HAVE_LIBTSS
int divert_tpm2_pksign (ctrl_t ctrl, const char *desc_text,
const unsigned char *digest, size_t digestlen, int algo,
const unsigned char *shadow_info, unsigned char **r_sig,
size_t *r_siglen);
int divert_tpm2_pkdecrypt (ctrl_t ctrl, const char *desc_text,
const unsigned char *cipher,
const unsigned char *shadow_info,
char **r_buf, size_t *r_len, int *r_padding);
int divert_tpm2_writekey (ctrl_t ctrl, const unsigned char *grip,
gcry_sexp_t s_skey);
#else /*!HAVE_LIBTSS*/
static inline int
divert_tpm2_pksign (ctrl_t ctrl, const char *desc_text,
const unsigned char *digest,
size_t digestlen, int algo,
const unsigned char *shadow_info,
unsigned char **r_sig,
size_t *r_siglen)
{
(void)ctrl; (void)desc_text; (void)digest; (void)digestlen;
(void)algo; (void)shadow_info; (void)r_sig; (void)r_siglen;
return gpg_error (GPG_ERR_NOT_SUPPORTED);
}
static inline int
divert_tpm2_pkdecrypt (ctrl_t ctrl, const char *desc_text,
const unsigned char *cipher,
const unsigned char *shadow_info,
char **r_buf, size_t *r_len,
int *r_padding)
{
(void)ctrl; (void)desc_text; (void)cipher; (void)shadow_info;
(void)r_buf; (void)r_len; (void)r_padding;
return gpg_error (GPG_ERR_NOT_SUPPORTED);
}
static inline int
divert_tpm2_writekey (ctrl_t ctrl, const unsigned char *grip,
gcry_sexp_t s_skey)
{
(void)ctrl; (void)grip; (void)s_key;
return gpg_error (GPG_ERR_NOT_SUPPORTED);
}
#endif /*!HAVE_LIBTSS*/
/*-- divert-scd.c --*/
int divert_pksign (ctrl_t ctrl, const char *desc_text,
@ -606,6 +654,16 @@ void agent_daemon_check_aliveness (void);
void agent_reset_daemon (ctrl_t ctrl);
void agent_kill_daemon (enum daemon_type type);
/*-- call-tpm2d.c --*/
int agent_tpm2d_writekey (ctrl_t ctrl, unsigned char **shadow_info,
gcry_sexp_t s_skey);
int agent_tpm2d_pksign (ctrl_t ctrl, const unsigned char *digest,
size_t digestlen, const unsigned char *shadow_info,
unsigned char **r_sig, size_t *r_siglen);
int agent_tpm2d_pkdecrypt (ctrl_t ctrl, const unsigned char *cipher,
size_t cipherlen, const unsigned char *shadow_info,
char **r_buf, size_t *r_len);
/*-- call-scd.c --*/
int agent_card_learn (ctrl_t ctrl,
void (*kpinfo_cb)(void*, const char *),

3
agent/call-daemon.c
View File

@ -45,7 +45,8 @@
* same order as given by the daemon_type enum. */
static const int daemon_modules[DAEMON_MAX_TYPE] =
{
GNUPG_MODULE_NAME_SCDAEMON
GNUPG_MODULE_NAME_SCDAEMON,
GNUPG_MODULE_NAME_TPM2DAEMON
};
/* Definition of module local data of the CTRL structure. */

248
agent/call-tpm2d.c Normal file
View File

@ -0,0 +1,248 @@
#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 "agent.h"
#include <assuan.h>
#include "../common/strlist.h"
#include "../common/sexp-parse.h"
#include "../common/i18n.h"
static int
start_tpm2d (ctrl_t ctrl)
{
return daemon_start (DAEMON_TPM2D, ctrl);
}
static int
unlock_tpm2d (ctrl_t ctrl, gpg_error_t err)
{
return daemon_unlock (DAEMON_TPM2D, ctrl, err);
}
static assuan_context_t
daemon_ctx (ctrl_t ctrl)
{
return daemon_type_ctx (DAEMON_TPM2D, ctrl);
}
struct inq_parm_s {
assuan_context_t ctx;
gpg_error_t (*getpin_cb)(ctrl_t, const char *, char **);
ctrl_t ctrl;
/* The next fields are used by inq_keydata. */
const unsigned char *keydata;
size_t keydatalen;
/* following only used by inq_extra */
const unsigned char *extra;
size_t extralen;
char *pin;
};
static gpg_error_t
inq_needpin (void *opaque, const char *line)
{
struct inq_parm_s *parm = opaque;
char *pin = NULL;
gpg_error_t rc;
const char *s;
if ((s = has_leading_keyword (line, "NEEDPIN")))
{
rc = parm->getpin_cb (parm->ctrl, s, &pin);
if (!rc)
rc = assuan_send_data (parm->ctx, pin, strlen(pin));
parm->pin = pin;
}
else
{
log_error ("unsupported inquiry '%s'\n", line);
rc = gpg_error (GPG_ERR_ASS_UNKNOWN_INQUIRE);
}
return rc;
}
static gpg_error_t
inq_keydata (void *opaque, const char *line)
{
struct inq_parm_s *parm = opaque;
if (has_leading_keyword (line, "KEYDATA"))
return assuan_send_data (parm->ctx, parm->keydata, parm->keydatalen);
else
return inq_needpin (opaque, line);
}
static gpg_error_t
inq_extra (void *opaque, const char *line)
{
struct inq_parm_s *parm = opaque;
if (has_leading_keyword (line, "EXTRA"))
return assuan_send_data (parm->ctx, parm->extra, parm->extralen);
else
return inq_keydata (opaque, line);
}
int
agent_tpm2d_writekey (ctrl_t ctrl, unsigned char **shadow_info,
gcry_sexp_t s_skey)
{
int rc;
char line[ASSUAN_LINELENGTH];
size_t n;
unsigned char *kbuf;
membuf_t data;
struct inq_parm_s inqparm;
size_t len;
rc = start_tpm2d (ctrl);
if (rc)
return rc;
/* note: returned data is TPM protected so no need for a sensitive context */
init_membuf(&data, 4096);
inqparm.ctx = daemon_ctx (ctrl);
inqparm.getpin_cb = agent_ask_new_passphrase;
inqparm.ctrl = ctrl;
inqparm.pin = NULL;
n = gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, NULL, 0);
kbuf = xtrymalloc (n);
gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, kbuf, n);
inqparm.keydata = kbuf;
inqparm.keydatalen = n;
snprintf(line, sizeof(line), "IMPORT");
rc = assuan_transact (daemon_ctx (ctrl), line,
put_membuf_cb, &data,
inq_keydata, &inqparm,
NULL, NULL);
xfree (kbuf);
xfree (inqparm.pin);
if (rc)
{
xfree (get_membuf (&data, &len));
return unlock_tpm2d (ctrl, rc);
}
*shadow_info = get_membuf (&data, &len);
return unlock_tpm2d (ctrl, 0);
}
static gpg_error_t
pin_cb (ctrl_t ctrl, const char *prompt, char **passphrase)
{
*passphrase = agent_get_cache (ctrl, ctrl->keygrip, CACHE_MODE_USER);
if (*passphrase)
return 0;
return agent_get_passphrase(ctrl, passphrase,
_("Please enter your passphrase, so that the "
"secret key can be unlocked for this session"),
prompt, NULL, 0,
ctrl->keygrip, CACHE_MODE_USER, NULL);
}
int
agent_tpm2d_pksign (ctrl_t ctrl, const unsigned char *digest,
size_t digestlen, const unsigned char *shadow_info,
unsigned char **r_sig, size_t *r_siglen)
{
int rc;
char line[ASSUAN_LINELENGTH];
membuf_t data;
struct inq_parm_s inqparm;
rc = start_tpm2d (ctrl);
if (rc)
return rc;
init_membuf (&data, 1024);
inqparm.ctx = daemon_ctx (ctrl);
inqparm.getpin_cb = pin_cb;
inqparm.ctrl = ctrl;
inqparm.keydata = shadow_info;
inqparm.keydatalen = gcry_sexp_canon_len (shadow_info, 0, NULL, NULL);
inqparm.extra = digest;
inqparm.extralen = digestlen;
inqparm.pin = NULL;
snprintf(line, sizeof(line), "PKSIGN");
rc = assuan_transact (daemon_ctx (ctrl), line,
put_membuf_cb, &data,
inq_extra, &inqparm,
NULL, NULL);
if (!rc)
agent_put_cache (ctrl, ctrl->keygrip, CACHE_MODE_USER, inqparm.pin, 0);
xfree (inqparm.pin);
if (rc)
{
size_t len;
xfree (get_membuf (&data, &len));
return unlock_tpm2d (ctrl, rc);
}
*r_sig = get_membuf (&data, r_siglen);
return unlock_tpm2d (ctrl, 0);
}
int
agent_tpm2d_pkdecrypt (ctrl_t ctrl, const unsigned char *cipher,
size_t cipherlen, const unsigned char *shadow_info,
char **r_buf, size_t *r_len)
{
int rc;
char line[ASSUAN_LINELENGTH];
membuf_t data;
struct inq_parm_s inqparm;
rc = start_tpm2d (ctrl);
if (rc)
return rc;
init_membuf (&data, 1024);
inqparm.ctx = daemon_ctx (ctrl);
inqparm.getpin_cb = pin_cb;
inqparm.ctrl = ctrl;
inqparm.keydata = shadow_info;
inqparm.keydatalen = gcry_sexp_canon_len (shadow_info, 0, NULL, NULL);
inqparm.extra = cipher;
inqparm.extralen = cipherlen;
inqparm.pin = NULL;
snprintf(line, sizeof(line), "PKDECRYPT");
rc = assuan_transact (daemon_ctx (ctrl), line,
put_membuf_cb, &data,
inq_extra, &inqparm,
NULL, NULL);
if (!rc)
agent_put_cache (ctrl, ctrl->keygrip, CACHE_MODE_USER, inqparm.pin, 0);
xfree (inqparm.pin);
if (rc)
{
size_t len;
xfree (get_membuf (&data, &len));
return unlock_tpm2d (ctrl, rc);
}
*r_buf = get_membuf (&data, r_len);
return unlock_tpm2d (ctrl, 0);
}

5
agent/command.c
View File

@ -1314,6 +1314,11 @@ do_one_keyinfo (ctrl_t ctrl, const unsigned char *grip, assuan_context_t ctx,
if (err)
goto leave;
}
else if (strcmp (shadow_info_type, "tpm2-v1") == 0)
{
serialno = xstrdup("TPM-Protected");
idstr = NULL;
}
else
{
log_error ("unrecognised shadow key type %s\n", shadow_info_type);

145
agent/divert-tpm2.c Normal file
View File

@ -0,0 +1,145 @@
#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 "agent.h"
#include "../common/i18n.h"
#include "../common/sexp-parse.h"
int
divert_tpm2_pksign (ctrl_t ctrl, const char *desc_text,
const unsigned char *digest, size_t digestlen, int algo,
const unsigned char *shadow_info, unsigned char **r_sig,
size_t *r_siglen)
{
return agent_tpm2d_pksign(ctrl, digest, digestlen,
shadow_info, r_sig, r_siglen);
}
static gpg_error_t
agent_write_tpm2_shadow_key (ctrl_t ctrl, const unsigned char *grip,
unsigned char *shadow_info)
{
gpg_error_t err;
unsigned char *shdkey;
unsigned char *pkbuf;
size_t len;
gcry_sexp_t s_pkey;
err = agent_public_key_from_file (ctrl, grip, &s_pkey);
len = gcry_sexp_sprint(s_pkey, GCRYSEXP_FMT_CANON, NULL, 0);
pkbuf = xtrymalloc (len);
gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, pkbuf, len);
gcry_sexp_release (s_pkey);
err = agent_shadow_key_type (pkbuf, shadow_info, "tpm2-v1", &shdkey);
xfree (pkbuf);
if (err)
{
log_error ("shadowing the key failed: %s\n", gpg_strerror (err));
return err;
}
len = gcry_sexp_canon_len (shdkey, 0, NULL, NULL);
err = agent_write_private_key (grip, shdkey, len, 1 /*force*/,
NULL, NULL, 0);
xfree (shdkey);
if (err)
log_error ("error writing key: %s\n", gpg_strerror (err));
return err;
}
int
divert_tpm2_writekey (ctrl_t ctrl, const unsigned char *grip,
gcry_sexp_t s_skey)
{
int ret;
/* shadow_info is always shielded so no special handling required */
unsigned char *shadow_info;
ret = agent_tpm2d_writekey(ctrl, &shadow_info, s_skey);
if (!ret) {
ret = agent_write_tpm2_shadow_key (ctrl, grip, shadow_info);
xfree (shadow_info);
}
return ret;
}
int
divert_tpm2_pkdecrypt (ctrl_t ctrl, const char *desc_text,
const unsigned char *cipher,
const unsigned char *shadow_info,
char **r_buf, size_t *r_len, int *r_padding)
{
const unsigned char *s;
size_t n;
*r_padding = -1;
(void)desc_text;
s = cipher;
if (*s != '(')
return gpg_error (GPG_ERR_INV_SEXP);
s++;
n = snext (&s);
if (!n)
return gpg_error (GPG_ERR_INV_SEXP);
if (!smatch (&s, n, "enc-val"))
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
if (*s != '(')
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
s++;
n = snext (&s);
if (!n)
return gpg_error (GPG_ERR_INV_SEXP);
if (smatch (&s, n, "rsa"))
{
*r_padding = 0;
if (*s != '(')
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
s++;
n = snext (&s);
if (!n)
return gpg_error (GPG_ERR_INV_SEXP);
if (!smatch (&s, n, "a"))
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
n = snext (&s);
}
else if (smatch (&s, n, "ecdh"))
{
if (*s != '(')
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
s++;
n = snext (&s);
if (!n)
return gpg_error (GPG_ERR_INV_SEXP);
if (smatch (&s, n, "s"))
{
n = snext (&s);
s += n;
if (*s++ != ')')
return gpg_error (GPG_ERR_INV_SEXP);
if (*s++ != '(')
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
n = snext (&s);
if (!n)
return gpg_error (GPG_ERR_INV_SEXP);
}
if (!smatch (&s, n, "e"))
return gpg_error (GPG_ERR_UNKNOWN_SEXP);
n = snext (&s);
}
else
return gpg_error (GPG_ERR_UNSUPPORTED_ALGORITHM);
return agent_tpm2d_pkdecrypt (ctrl, s, n, shadow_info, r_buf, r_len);
}

12
agent/gpg-agent.c
View File

@ -102,6 +102,7 @@ enum cmd_and_opt_values
oLCmessages,
oXauthority,
oScdaemonProgram,
oTpm2daemonProgram,
oDefCacheTTL,
oDefCacheTTLSSH,
oMaxCacheTTL,
@ -199,6 +200,8 @@ static gpgrt_opt_t opts[] = {
/* */ N_("do not use the SCdaemon") ),
ARGPARSE_s_s (oScdaemonProgram, "scdaemon-program",
/* */ N_("|PGM|use PGM as the SCdaemon program") ),
ARGPARSE_s_s (oTpm2daemonProgram, "tpm2daemon-program",
/* */ N_("|PGM|use PGM as the tpm2daemon program") ),
ARGPARSE_s_n (oDisableCheckOwnSocket, "disable-check-own-socket", "@"),
ARGPARSE_s_s (oExtraSocket, "extra-socket",
@ -905,7 +908,14 @@ parse_rereadable_options (gpgrt_argparse_t *pargs, int reread)
opt.pinentry_invisible_char = xtrystrdup (pargs->r.ret_str); break;
break;
case oPinentryTimeout: opt.pinentry_timeout = pargs->r.ret_ulong; break;
case oScdaemonProgram: opt.daemon_program[DAEMON_SCD] = pargs->r.ret_str; break;
case oTpm2daemonProgram:
opt.daemon_program[DAEMON_TPM2D] = pargs->r.ret_str;
break;
case oScdaemonProgram:
opt.daemon_program[DAEMON_SCD] = pargs->r.ret_str;
break;
case oDisableScdaemon: opt.disable_daemon[DAEMON_SCD] = 1; break;
case oDisableCheckOwnSocket: disable_check_own_socket = 1; break;

12
agent/keyformat.txt
View File

@ -312,8 +312,9 @@ to keys stored on a token:
(comment whatever)
)
The currently used protocol is "t1-v1" (token info version 1). The
second list with the information has this layout:
The currently used protocols are "t1-v1" (token info version 1) and
"tpm2-v1" (TPM format key information). The second list with the
information has this layout for "t1-v1":
(card_serial_number id_string_of_key fixed_pin_length)
@ -322,6 +323,13 @@ the PIN; a value of 0 indicates that this information is not
available. The rationale for this field is that some pinpad equipped
readers don't allow passing a variable length PIN.
This is the (info) layout for "tpm2-v1":
(parent tpm_private_string tpm_public_string)
Although this precise format is encapsulated inside the tpm2daemon
itself and nothing in gpg ever uses this.
More items may be added to the list.
** OpenPGP Private Key Transfer Format

4
agent/pkdecrypt.c
View File

@ -88,6 +88,10 @@ agent_pkdecrypt (ctrl_t ctrl, const char *desc_text,
goto leave;
}
if (agent_is_tpm2_key (s_skey))
err = divert_tpm2_pkdecrypt (ctrl, desc_text, ciphertext, shadow_info,
&buf, &len, r_padding);
else
err = divert_pkdecrypt (ctrl, desc_text, ctrl->keygrip, ciphertext,
shadow_info, &buf, &len, r_padding);
if (err)

6
agent/pksign.c
View File

@ -397,6 +397,12 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce,
if (desc_text)
agent_modify_description (desc_text, NULL, s_pkey, &desc2);
if (agent_is_tpm2_key (s_skey))
err = divert_tpm2_pksign (ctrl, desc2? desc2 : desc_text,
data, datalen,
ctrl->digest.algo,
shadow_info, &buf, &len);
else
err = divert_pksign (ctrl, desc2? desc2 : desc_text,
ctrl->keygrip,
data, datalen,

5
agent/protect.c
View File

@ -1679,6 +1679,7 @@ agent_get_shadow_info_type (const unsigned char *shadowkey,
return 0;
}
gpg_error_t
agent_get_shadow_info (const unsigned char *shadowkey,
unsigned char const **shadow_info)
@ -1686,6 +1687,7 @@ agent_get_shadow_info(const unsigned char *shadowkey,
return agent_get_shadow_info_type (shadowkey, shadow_info, NULL);
}
int
agent_is_tpm2_key (gcry_sexp_t s_skey)
{
@ -1701,12 +1703,14 @@ agent_is_tpm2_key(gcry_sexp_t s_skey)
err = agent_get_shadow_info_type (buf, NULL, &type);
if (err)
return 0;
xfree (buf);
err = strcmp (type, "tpm2-v1") == 0;
xfree (type);
return err;
}
gpg_error_t
agent_get_shadow_type (const unsigned char *shadowkey,
unsigned char **shadow_type)
@ -1714,6 +1718,7 @@ agent_get_shadow_type(const unsigned char *shadowkey,
return agent_get_shadow_info_type (shadowkey, NULL, shadow_type);
}
/* Parse the canonical encoded SHADOW_INFO S-expression. On success
the hex encoded serial number is returned as a malloced strings at
R_HEXSN and the Id string as a malloced string at R_IDSTR. On