openssh-portable/ssh-pkcs11-helper.c

457 lines
11 KiB
C

/* $OpenBSD: ssh-pkcs11-helper.c,v 1.23 2020/03/06 18:26:21 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"
#include <sys/types.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include "openbsd-compat/sys-queue.h"
#include <stdlib.h>
#include <errno.h>
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include "xmalloc.h"
#include "sshbuf.h"
#include "log.h"
#include "misc.h"
#include "sshkey.h"
#include "authfd.h"
#include "ssh-pkcs11.h"
#include "ssherr.h"
#ifdef ENABLE_PKCS11
#ifdef WITH_OPENSSL
/* borrows code from sftp-server and ssh-agent */
struct pkcs11_keyinfo {
struct sshkey *key;
char *providername, *label;
TAILQ_ENTRY(pkcs11_keyinfo) next;
};
TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist;
#define MAX_MSG_LENGTH 10240 /*XXX*/
/* input and output queue */
struct sshbuf *iqueue;
struct sshbuf *oqueue;
static void
add_key(struct sshkey *k, char *name, char *label)
{
struct pkcs11_keyinfo *ki;
ki = xcalloc(1, sizeof(*ki));
ki->providername = xstrdup(name);
ki->key = k;
ki->label = xstrdup(label);
TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next);
}
static void
del_keys_by_name(char *name)
{
struct pkcs11_keyinfo *ki, *nxt;
for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) {
nxt = TAILQ_NEXT(ki, next);
if (!strcmp(ki->providername, name)) {
TAILQ_REMOVE(&pkcs11_keylist, ki, next);
free(ki->providername);
free(ki->label);
sshkey_free(ki->key);
free(ki);
}
}
}
/* lookup matching 'private' key */
static struct sshkey *
lookup_key(struct sshkey *k)
{
struct pkcs11_keyinfo *ki;
TAILQ_FOREACH(ki, &pkcs11_keylist, next) {
debug("check %p %s %s", ki, ki->providername, ki->label);
if (sshkey_equal(k, ki->key))
return (ki->key);
}
return (NULL);
}
static void
send_msg(struct sshbuf *m)
{
int r;
if ((r = sshbuf_put_stringb(oqueue, m)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
static void
process_add(void)
{
char *name, *pin;
struct sshkey **keys = NULL;
int r, i, nkeys;
u_char *blob;
size_t blen;
struct sshbuf *msg;
char **labels = NULL;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 ||
(r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((nkeys = pkcs11_add_provider(name, pin, &keys, &labels)) > 0) {
if ((r = sshbuf_put_u8(msg,
SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
(r = sshbuf_put_u32(msg, nkeys)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
for (i = 0; i < nkeys; i++) {
if ((r = sshkey_to_blob(keys[i], &blob, &blen)) != 0) {
debug("%s: sshkey_to_blob: %s",
__func__, ssh_err(r));
continue;
}
if ((r = sshbuf_put_string(msg, blob, blen)) != 0 ||
(r = sshbuf_put_cstring(msg, labels[i])) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
free(blob);
add_key(keys[i], name, labels[i]);
free(labels[i]);
}
} else {
if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((r = sshbuf_put_u32(msg, -nkeys)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
free(labels);
free(keys); /* keys themselves are transferred to pkcs11_keylist */
free(pin);
free(name);
send_msg(msg);
sshbuf_free(msg);
}
static void
process_del(void)
{
char *name, *pin;
struct sshbuf *msg;
int r;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 ||
(r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
del_keys_by_name(name);
if ((r = sshbuf_put_u8(msg, pkcs11_del_provider(name) == 0 ?
SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
free(pin);
free(name);
send_msg(msg);
sshbuf_free(msg);
}
static void
process_sign(void)
{
u_char *blob, *data, *signature = NULL;
size_t blen, dlen, slen = 0;
int r, ok = -1;
struct sshkey *key, *found;
struct sshbuf *msg;
/* XXX support SHA2 signature flags */
if ((r = sshbuf_get_string(iqueue, &blob, &blen)) != 0 ||
(r = sshbuf_get_string(iqueue, &data, &dlen)) != 0 ||
(r = sshbuf_get_u32(iqueue, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
error("%s: sshkey_from_blob: %s", __func__, ssh_err(r));
else {
if ((found = lookup_key(key)) != NULL) {
#ifdef WITH_OPENSSL
int ret;
if (key->type == KEY_RSA) {
slen = RSA_size(key->rsa);
signature = xmalloc(slen);
ret = RSA_private_encrypt(dlen, data, signature,
found->rsa, RSA_PKCS1_PADDING);
if (ret != -1) {
slen = ret;
ok = 0;
}
#ifdef OPENSSL_HAS_ECC
} else if (key->type == KEY_ECDSA) {
u_int xslen = ECDSA_size(key->ecdsa);
signature = xmalloc(xslen);
/* "The parameter type is ignored." */
ret = ECDSA_sign(-1, data, dlen, signature,
&xslen, found->ecdsa);
if (ret != 0)
ok = 0;
else
error("%s: ECDSA_sign"
" returns %d", __func__, ret);
slen = xslen;
#endif /* OPENSSL_HAS_ECC */
} else
error("%s: don't know how to sign with key "
"type %d", __func__, (int)key->type);
#endif /* WITH_OPENSSL */
}
sshkey_free(key);
}
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if (ok == 0) {
if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
(r = sshbuf_put_string(msg, signature, slen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
} else {
if ((r = sshbuf_put_u8(msg, SSH2_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
free(data);
free(blob);
free(signature);
send_msg(msg);
sshbuf_free(msg);
}
static void
process(void)
{
u_int msg_len;
u_int buf_len;
u_int consumed;
u_char type;
const u_char *cp;
int r;
buf_len = sshbuf_len(iqueue);
if (buf_len < 5)
return; /* Incomplete message. */
cp = sshbuf_ptr(iqueue);
msg_len = get_u32(cp);
if (msg_len > MAX_MSG_LENGTH) {
error("bad message len %d", msg_len);
cleanup_exit(11);
}
if (buf_len < msg_len + 4)
return;
if ((r = sshbuf_consume(iqueue, 4)) != 0 ||
(r = sshbuf_get_u8(iqueue, &type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
buf_len -= 4;
switch (type) {
case SSH_AGENTC_ADD_SMARTCARD_KEY:
debug("process_add");
process_add();
break;
case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
debug("process_del");
process_del();
break;
case SSH2_AGENTC_SIGN_REQUEST:
debug("process_sign");
process_sign();
break;
default:
error("Unknown message %d", type);
break;
}
/* discard the remaining bytes from the current packet */
if (buf_len < sshbuf_len(iqueue)) {
error("iqueue grew unexpectedly");
cleanup_exit(255);
}
consumed = buf_len - sshbuf_len(iqueue);
if (msg_len < consumed) {
error("msg_len %d < consumed %d", msg_len, consumed);
cleanup_exit(255);
}
if (msg_len > consumed) {
if ((r = sshbuf_consume(iqueue, msg_len - consumed)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
}
void
cleanup_exit(int i)
{
/* XXX */
_exit(i);
}
int
main(int argc, char **argv)
{
int r, ch, in, out, log_stderr = 0;
ssize_t len;
SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
LogLevel log_level = SYSLOG_LEVEL_ERROR;
char buf[4*4096];
extern char *__progname;
struct pollfd pfd[2];
__progname = ssh_get_progname(argv[0]);
seed_rng();
TAILQ_INIT(&pkcs11_keylist);
log_init(__progname, log_level, log_facility, log_stderr);
while ((ch = getopt(argc, argv, "v")) != -1) {
switch (ch) {
case 'v':
log_stderr = 1;
if (log_level == SYSLOG_LEVEL_ERROR)
log_level = SYSLOG_LEVEL_DEBUG1;
else if (log_level < SYSLOG_LEVEL_DEBUG3)
log_level++;
break;
default:
fprintf(stderr, "usage: %s [-v]\n", __progname);
exit(1);
}
}
log_init(__progname, log_level, log_facility, log_stderr);
pkcs11_init(0);
in = STDIN_FILENO;
out = STDOUT_FILENO;
if ((iqueue = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((oqueue = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
while (1) {
memset(pfd, 0, sizeof(pfd));
pfd[0].fd = in;
pfd[1].fd = out;
/*
* Ensure that we can read a full buffer and handle
* the worst-case length packet it can generate,
* otherwise apply backpressure by stopping reads.
*/
if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 &&
(r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0)
pfd[0].events = POLLIN;
else if (r != SSH_ERR_NO_BUFFER_SPACE)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (sshbuf_len(oqueue) > 0)
pfd[1].events = POLLOUT;
if ((r = poll(pfd, 2, -1 /* INFTIM */)) <= 0) {
if (r == 0 || errno == EINTR)
continue;
fatal("poll: %s", strerror(errno));
}
/* copy stdin to iqueue */
if ((pfd[0].revents & (POLLIN|POLLERR)) != 0) {
len = read(in, buf, sizeof buf);
if (len == 0) {
debug("read eof");
cleanup_exit(0);
} else if (len < 0) {
error("read: %s", strerror(errno));
cleanup_exit(1);
} else if ((r = sshbuf_put(iqueue, buf, len)) != 0) {
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
}
}
/* send oqueue to stdout */
if ((pfd[1].revents & (POLLOUT|POLLHUP)) != 0) {
len = write(out, sshbuf_ptr(oqueue),
sshbuf_len(oqueue));
if (len < 0) {
error("write: %s", strerror(errno));
cleanup_exit(1);
} else if ((r = sshbuf_consume(oqueue, len)) != 0) {
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
}
}
/*
* Process requests from client if we can fit the results
* into the output buffer, otherwise stop processing input
* and let the output queue drain.
*/
if ((r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0)
process();
else if (r != SSH_ERR_NO_BUFFER_SPACE)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
}
#else /* WITH_OPENSSL */
void
cleanup_exit(int i)
{
_exit(i);
}
int
main(int argc, char **argv)
{
fprintf(stderr, "PKCS#11 code is not enabled\n");
return 1;
}
#endif /* WITH_OPENSSL */
#else /* ENABLE_PKCS11 */
int
main(int argc, char **argv)
{
extern char *__progname;
__progname = ssh_get_progname(argv[0]);
log_init(__progname, SYSLOG_LEVEL_ERROR, SYSLOG_FACILITY_AUTH, 0);
fatal("PKCS#11 support disabled at compile time");
}
#endif /* ENABLE_PKCS11 */