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gnupg/agent/pkdecrypt.c

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/* pkdecrypt.c - public key decryption (well, actually using a secret key)
* Copyright (C) 2001, 2003 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
2007-07-04 19:49:40 +00:00
* the Free Software Foundation; either version 3 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, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/stat.h>
#include "agent.h"
/* DECRYPT the stuff in ciphertext which is expected to be a S-Exp.
Try to get the key from CTRL and write the decoded stuff back to
OUTFP. The padding information is stored at R_PADDING with -1
for not known. */
gpg_error_t
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agent_pkdecrypt (ctrl_t ctrl, const char *desc_text,
const unsigned char *ciphertext, size_t ciphertextlen,
membuf_t *outbuf, int *r_padding)
{
gcry_sexp_t s_skey = NULL, s_cipher = NULL, s_plain = NULL;
unsigned char *shadow_info = NULL;
gpg_error_t err = 0;
int no_shadow_info = 0;
char *buf = NULL;
size_t len;
*r_padding = -1;
if (!ctrl->have_keygrip)
{
log_error ("speculative decryption not yet supported\n");
err = gpg_error (GPG_ERR_NO_SECKEY);
goto leave;
}
err = gcry_sexp_sscan (&s_cipher, NULL, (char*)ciphertext, ciphertextlen);
if (err)
{
log_error ("failed to convert ciphertext: %s\n", gpg_strerror (err));
err = gpg_error (GPG_ERR_INV_DATA);
goto leave;
}
if (DBG_CRYPTO)
{
log_printhex (ctrl->keygrip, 20, "keygrip:");
log_printhex (ciphertext, ciphertextlen, "cipher: ");
}
err = agent_key_from_file (ctrl, NULL, desc_text,
NULL, &shadow_info,
CACHE_MODE_NORMAL, NULL, &s_skey, NULL, NULL);
if (gpg_err_code (err) == GPG_ERR_NO_SECKEY)
no_shadow_info = 1;
else if (err)
{
if (gpg_err_code (err) != GPG_ERR_NO_SECKEY)
log_error ("failed to read the secret key\n");
goto leave;
}
if (shadow_info || no_shadow_info)
{ /* divert operation to the smartcard */
if (!gcry_sexp_canon_len (ciphertext, ciphertextlen, NULL, NULL))
{
err = gpg_error (GPG_ERR_INV_SEXP);
goto leave;
}
agent: Add new shadow key type and functions to call tpm2daemon * 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>
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if (agent_is_tpm2_key (s_skey))
err = divert_tpm2_pkdecrypt (ctrl, ciphertext, shadow_info,
agent: Add new shadow key type and functions to call tpm2daemon * 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>
2021-03-09 13:50:29 -08:00
&buf, &len, r_padding);
else
err = divert_pkdecrypt (ctrl, ctrl->keygrip, ciphertext,
&buf, &len, r_padding);
if (err)
{
log_error ("smartcard decryption failed: %s\n", gpg_strerror (err));
goto leave;
}
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put_membuf_printf (outbuf, "(5:value%u:", (unsigned int)len);
put_membuf (outbuf, buf, len);
put_membuf (outbuf, ")", 2);
}
else
{ /* No smartcard, but a private key */
/* if (DBG_CRYPTO ) */
/* { */
/* log_debug ("skey: "); */
/* gcry_sexp_dump (s_skey); */
/* } */
err = gcry_pk_decrypt (&s_plain, s_cipher, s_skey);
if (err)
{
log_error ("decryption failed: %s\n", gpg_strerror (err));
goto leave;
}
if (DBG_CRYPTO)
{
log_debug ("plain: ");
gcry_sexp_dump (s_plain);
}
len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, NULL, 0);
log_assert (len);
buf = xmalloc (len);
len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, buf, len);
log_assert (len);
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if (*buf == '(')
put_membuf (outbuf, buf, len);
else
{
/* Old style libgcrypt: This is only an S-expression
part. Turn it into a complete S-expression. */
put_membuf (outbuf, "(5:value", 8);
put_membuf (outbuf, buf, len);
put_membuf (outbuf, ")", 2);
}
}
leave:
gcry_sexp_release (s_skey);
gcry_sexp_release (s_plain);
gcry_sexp_release (s_cipher);
xfree (buf);
xfree (shadow_info);
return err;
}