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/* $OpenBSD: ssh-pkcs11-client.c,v 1.10 2018/07/09 21:59:10 markus Exp $ */
/*
* Copyright (c) 2010 Markus Friedl. All rights reserved.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#ifdef ENABLE_PKCS11
#include <sys/types.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <sys/socket.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <openssl/rsa.h>
#include "openbsd-compat/openssl-compat.h"
#include "pathnames.h"
#include "xmalloc.h"
#include "sshbuf.h"
#include "log.h"
#include "misc.h"
#include "sshkey.h"
#include "authfd.h"
#include "atomicio.h"
#include "ssh-pkcs11.h"
#include "ssherr.h"
/* borrows code from sftp-server and ssh-agent */
int fd = -1;
pid_t pid = -1;
static void
send_msg(struct sshbuf *m)
{
u_char buf[4];
size_t mlen = sshbuf_len(m);
int r;
POKE_U32(buf, mlen);
if (atomicio(vwrite, fd, buf, 4) != 4 ||
atomicio(vwrite, fd, sshbuf_mutable_ptr(m),
sshbuf_len(m)) != sshbuf_len(m))
error("write to helper failed");
if ((r = sshbuf_consume(m, mlen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
static int
recv_msg(struct sshbuf *m)
{
u_int l, len;
u_char c, buf[1024];
int r;
if ((len = atomicio(read, fd, buf, 4)) != 4) {
error("read from helper failed: %u", len);
return (0); /* XXX */
}
len = PEEK_U32(buf);
if (len > 256 * 1024)
fatal("response too long: %u", len);
/* read len bytes into m */
sshbuf_reset(m);
while (len > 0) {
l = len;
if (l > sizeof(buf))
l = sizeof(buf);
if (atomicio(read, fd, buf, l) != l) {
error("response from helper failed.");
return (0); /* XXX */
}
if ((r = sshbuf_put(m, buf, l)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
len -= l;
}
if ((r = sshbuf_get_u8(m, &c)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
return c;
}
int
pkcs11_init(int interactive)
{
return (0);
}
void
pkcs11_terminate(void)
{
if (fd >= 0)
close(fd);
}
static int
pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
int padding)
{
struct sshkey key; /* XXX */
u_char *blob, *signature = NULL;
size_t blen, slen = 0;
int r, ret = -1;
struct sshbuf *msg;
if (padding != RSA_PKCS1_PADDING)
return (-1);
key.type = KEY_RSA;
key.rsa = rsa;
if ((r = sshkey_to_blob(&key, &blob, &blen)) != 0) {
error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
return -1;
}
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
(r = sshbuf_put_string(msg, blob, blen)) != 0 ||
(r = sshbuf_put_string(msg, from, flen)) != 0 ||
(r = sshbuf_put_u32(msg, 0)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
free(blob);
send_msg(msg);
sshbuf_reset(msg);
if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) {
if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (slen <= (size_t)RSA_size(rsa)) {
memcpy(to, signature, slen);
ret = slen;
}
free(signature);
}
sshbuf_free(msg);
return (ret);
}
/* redirect the private key encrypt operation to the ssh-pkcs11-helper */
static int
wrap_key(RSA *rsa)
{
static RSA_METHOD *helper_rsa;
if ((helper_rsa = RSA_meth_dup(RSA_get_default_method())) == NULL)
fatal("%s: RSA_meth_dup failed", __func__);
if (!RSA_meth_set1_name(helper_rsa, "ssh-pkcs11-helper") ||
!RSA_meth_set_priv_enc(helper_rsa, pkcs11_rsa_private_encrypt))
fatal("%s: failed to prepare method", __func__);
RSA_set_method(rsa, helper_rsa);
return (0);
}
static int
pkcs11_start_helper(void)
{
int pair[2];
if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
error("socketpair: %s", strerror(errno));
return (-1);
}
if ((pid = fork()) == -1) {
error("fork: %s", strerror(errno));
return (-1);
} else if (pid == 0) {
if ((dup2(pair[1], STDIN_FILENO) == -1) ||
(dup2(pair[1], STDOUT_FILENO) == -1)) {
fprintf(stderr, "dup2: %s\n", strerror(errno));
_exit(1);
}
close(pair[0]);
close(pair[1]);
execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER,
(char *)NULL);
fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER,
strerror(errno));
_exit(1);
}
close(pair[1]);
fd = pair[0];
return (0);
}
int
pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp)
{
struct sshkey *k;
int r;
u_char *blob;
size_t blen;
u_int nkeys, i;
struct sshbuf *msg;
if (fd < 0 && pkcs11_start_helper() < 0)
return (-1);
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_u8(msg, SSH_AGENTC_ADD_SMARTCARD_KEY)) != 0 ||
(r = sshbuf_put_cstring(msg, name)) != 0 ||
(r = sshbuf_put_cstring(msg, pin)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
send_msg(msg);
sshbuf_reset(msg);
if (recv_msg(msg) == SSH2_AGENT_IDENTITIES_ANSWER) {
if ((r = sshbuf_get_u32(msg, &nkeys)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
*keysp = xcalloc(nkeys, sizeof(struct sshkey *));
for (i = 0; i < nkeys; i++) {
/* XXX clean up properly instead of fatal() */
if ((r = sshbuf_get_string(msg, &blob, &blen)) != 0 ||
(r = sshbuf_skip_string(msg)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
if ((r = sshkey_from_blob(blob, blen, &k)) != 0)
fatal("%s: bad key: %s", __func__, ssh_err(r));
wrap_key(k->rsa);
(*keysp)[i] = k;
free(blob);
}
} else {
nkeys = -1;
}
sshbuf_free(msg);
return (nkeys);
}
int
pkcs11_del_provider(char *name)
{
int r, ret = -1;
struct sshbuf *msg;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_u8(msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY)) != 0 ||
(r = sshbuf_put_cstring(msg, name)) != 0 ||
(r = sshbuf_put_cstring(msg, "")) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
send_msg(msg);
sshbuf_reset(msg);
if (recv_msg(msg) == SSH_AGENT_SUCCESS)
ret = 0;
sshbuf_free(msg);
return (ret);
}
#endif /* ENABLE_PKCS11 */
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