openssh-portable/ssh-pkcs11-helper.c

370 lines
7.9 KiB
C

/* $OpenBSD: ssh-pkcs11-helper.c,v 1.6 2013/05/17 00:13:14 djm 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 <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "xmalloc.h"
#include "buffer.h"
#include "log.h"
#include "misc.h"
#include "key.h"
#include "authfd.h"
#include "ssh-pkcs11.h"
#ifdef ENABLE_PKCS11
/* borrows code from sftp-server and ssh-agent */
struct pkcs11_keyinfo {
Key *key;
char *providername;
TAILQ_ENTRY(pkcs11_keyinfo) next;
};
TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist;
#define MAX_MSG_LENGTH 10240 /*XXX*/
/* helper */
#define get_int() buffer_get_int(&iqueue);
#define get_string(lenp) buffer_get_string(&iqueue, lenp);
/* input and output queue */
Buffer iqueue;
Buffer oqueue;
static void
add_key(Key *k, char *name)
{
struct pkcs11_keyinfo *ki;
ki = xcalloc(1, sizeof(*ki));
ki->providername = xstrdup(name);
ki->key = k;
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);
key_free(ki->key);
free(ki);
}
}
}
/* lookup matching 'private' key */
static Key *
lookup_key(Key *k)
{
struct pkcs11_keyinfo *ki;
TAILQ_FOREACH(ki, &pkcs11_keylist, next) {
debug("check %p %s", ki, ki->providername);
if (key_equal(k, ki->key))
return (ki->key);
}
return (NULL);
}
static void
send_msg(Buffer *m)
{
int mlen = buffer_len(m);
buffer_put_int(&oqueue, mlen);
buffer_append(&oqueue, buffer_ptr(m), mlen);
buffer_consume(m, mlen);
}
static void
process_add(void)
{
char *name, *pin;
Key **keys;
int i, nkeys;
u_char *blob;
u_int blen;
Buffer msg;
buffer_init(&msg);
name = get_string(NULL);
pin = get_string(NULL);
if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) {
buffer_put_char(&msg, SSH2_AGENT_IDENTITIES_ANSWER);
buffer_put_int(&msg, nkeys);
for (i = 0; i < nkeys; i++) {
key_to_blob(keys[i], &blob, &blen);
buffer_put_string(&msg, blob, blen);
buffer_put_cstring(&msg, name);
free(blob);
add_key(keys[i], name);
}
free(keys);
} else {
buffer_put_char(&msg, SSH_AGENT_FAILURE);
}
free(pin);
free(name);
send_msg(&msg);
buffer_free(&msg);
}
static void
process_del(void)
{
char *name, *pin;
Buffer msg;
buffer_init(&msg);
name = get_string(NULL);
pin = get_string(NULL);
del_keys_by_name(name);
if (pkcs11_del_provider(name) == 0)
buffer_put_char(&msg, SSH_AGENT_SUCCESS);
else
buffer_put_char(&msg, SSH_AGENT_FAILURE);
free(pin);
free(name);
send_msg(&msg);
buffer_free(&msg);
}
static void
process_sign(void)
{
u_char *blob, *data, *signature = NULL;
u_int blen, dlen, slen = 0;
int ok = -1, ret;
Key *key, *found;
Buffer msg;
blob = get_string(&blen);
data = get_string(&dlen);
(void)get_int(); /* XXX ignore flags */
if ((key = key_from_blob(blob, blen)) != NULL) {
if ((found = lookup_key(key)) != NULL) {
slen = RSA_size(key->rsa);
signature = xmalloc(slen);
if ((ret = RSA_private_encrypt(dlen, data, signature,
found->rsa, RSA_PKCS1_PADDING)) != -1) {
slen = ret;
ok = 0;
}
}
key_free(key);
}
buffer_init(&msg);
if (ok == 0) {
buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
buffer_put_string(&msg, signature, slen);
} else {
buffer_put_char(&msg, SSH_AGENT_FAILURE);
}
free(data);
free(blob);
free(signature);
send_msg(&msg);
buffer_free(&msg);
}
static void
process(void)
{
u_int msg_len;
u_int buf_len;
u_int consumed;
u_int type;
u_char *cp;
buf_len = buffer_len(&iqueue);
if (buf_len < 5)
return; /* Incomplete message. */
cp = buffer_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;
buffer_consume(&iqueue, 4);
buf_len -= 4;
type = buffer_get_char(&iqueue);
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 < buffer_len(&iqueue)) {
error("iqueue grew unexpectedly");
cleanup_exit(255);
}
consumed = buf_len - buffer_len(&iqueue);
if (msg_len < consumed) {
error("msg_len %d < consumed %d", msg_len, consumed);
cleanup_exit(255);
}
if (msg_len > consumed)
buffer_consume(&iqueue, msg_len - consumed);
}
void
cleanup_exit(int i)
{
/* XXX */
_exit(i);
}
int
main(int argc, char **argv)
{
fd_set *rset, *wset;
int in, out, max, log_stderr = 0;
ssize_t len, olen, set_size;
SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
LogLevel log_level = SYSLOG_LEVEL_ERROR;
char buf[4*4096];
extern char *__progname;
TAILQ_INIT(&pkcs11_keylist);
pkcs11_init(0);
seed_rng();
__progname = ssh_get_progname(argv[0]);
log_init(__progname, log_level, log_facility, log_stderr);
in = STDIN_FILENO;
out = STDOUT_FILENO;
max = 0;
if (in > max)
max = in;
if (out > max)
max = out;
buffer_init(&iqueue);
buffer_init(&oqueue);
set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
rset = (fd_set *)xmalloc(set_size);
wset = (fd_set *)xmalloc(set_size);
for (;;) {
memset(rset, 0, set_size);
memset(wset, 0, set_size);
/*
* 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 (buffer_check_alloc(&iqueue, sizeof(buf)) &&
buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
FD_SET(in, rset);
olen = buffer_len(&oqueue);
if (olen > 0)
FD_SET(out, wset);
if (select(max+1, rset, wset, NULL, NULL) < 0) {
if (errno == EINTR)
continue;
error("select: %s", strerror(errno));
cleanup_exit(2);
}
/* copy stdin to iqueue */
if (FD_ISSET(in, rset)) {
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 {
buffer_append(&iqueue, buf, len);
}
}
/* send oqueue to stdout */
if (FD_ISSET(out, wset)) {
len = write(out, buffer_ptr(&oqueue), olen);
if (len < 0) {
error("write: %s", strerror(errno));
cleanup_exit(1);
} else {
buffer_consume(&oqueue, len);
}
}
/*
* 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 (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
process();
}
}
#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 */