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/* $OpenBSD: ssh-pkcs11-client.c,v 1.7 2017/05/30 08:52:19 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 <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <openssl/rsa.h>
#include "pathnames.h"
#include "xmalloc.h"
#include "buffer.h"
#include "log.h"
#include "misc.h"
#include "key.h"
#include "authfd.h"
#include "atomicio.h"
#include "ssh-pkcs11.h"
/* borrows code from sftp-server and ssh-agent */
int fd = -1;
pid_t pid = -1;
static void
send_msg(Buffer *m)
{
u_char buf[4];
int mlen = buffer_len(m);
put_u32(buf, mlen);
if (atomicio(vwrite, fd, buf, 4) != 4 ||
atomicio(vwrite, fd, buffer_ptr(m),
buffer_len(m)) != buffer_len(m))
error("write to helper failed");
buffer_consume(m, mlen);
}
static int
recv_msg(Buffer *m)
{
u_int l, len;
u_char buf[1024];
if ((len = atomicio(read, fd, buf, 4)) != 4) {
error("read from helper failed: %u", len);
return (0); /* XXX */
}
len = get_u32(buf);
if (len > 256 * 1024)
fatal("response too long: %u", len);
/* read len bytes into m */
buffer_clear(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 */
}
buffer_append(m, buf, l);
len -= l;
}
return (buffer_get_char(m));
}
int
pkcs11_init(int interactive)
{
return (0);
}
void
pkcs11_terminate(void)
{
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;
u_int blen, slen = 0;
int ret = -1;
Buffer msg;
if (padding != RSA_PKCS1_PADDING)
return (-1);
key.type = KEY_RSA;
key.rsa = rsa;
if (key_to_blob(&key, &blob, &blen) == 0)
return -1;
buffer_init(&msg);
buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
buffer_put_string(&msg, blob, blen);
buffer_put_string(&msg, from, flen);
buffer_put_int(&msg, 0);
free(blob);
send_msg(&msg);
buffer_clear(&msg);
if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) {
signature = buffer_get_string(&msg, &slen);
if (slen <= (u_int)RSA_size(rsa)) {
memcpy(to, signature, slen);
ret = slen;
}
free(signature);
}
buffer_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;
memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa));
helper_rsa.name = "ssh-pkcs11-helper";
helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt;
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, Key ***keysp)
{
struct sshkey *k;
int i, nkeys;
u_char *blob;
u_int blen;
Buffer msg;
if (fd < 0 && pkcs11_start_helper() < 0)
return (-1);
buffer_init(&msg);
buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY);
buffer_put_cstring(&msg, name);
buffer_put_cstring(&msg, pin);
send_msg(&msg);
buffer_clear(&msg);
if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) {
nkeys = buffer_get_int(&msg);
*keysp = xcalloc(nkeys, sizeof(Key *));
for (i = 0; i < nkeys; i++) {
blob = buffer_get_string(&msg, &blen);
free(buffer_get_string(&msg, NULL));
k = key_from_blob(blob, blen);
wrap_key(k->rsa);
(*keysp)[i] = k;
free(blob);
}
} else {
nkeys = -1;
}
buffer_free(&msg);
return (nkeys);
}
int
pkcs11_del_provider(char *name)
{
int ret = -1;
Buffer msg;
buffer_init(&msg);
buffer_put_char(&msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY);
buffer_put_cstring(&msg, name);
buffer_put_cstring(&msg, "");
send_msg(&msg);
buffer_clear(&msg);
if (recv_msg(&msg) == SSH_AGENT_SUCCESS)
ret = 0;
buffer_free(&msg);
return (ret);
}
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