mirror of
git://anongit.mindrot.org/openssh.git
synced 2024-12-29 05:32:07 +00:00
fd6dcef203
When a forced-command appears in both a certificate and an authorized keys/principals command= restriction, refuse to accept the certificate unless they are identical. The previous (documented) behaviour of having the certificate forced- command override the other could be a bit confused and more error-prone. Pointed out by Jann Horn of Project Zero; ok dtucker@ Upstream-ID: 79d811b6eb6bbe1221bf146dde6928f92d2cd05f
658 lines
17 KiB
C
658 lines
17 KiB
C
/* $OpenBSD: auth-options.c,v 1.72 2016/11/30 02:57:40 djm Exp $ */
|
|
/*
|
|
* Author: Tatu Ylonen <ylo@cs.hut.fi>
|
|
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
* All rights reserved
|
|
* As far as I am concerned, the code I have written for this software
|
|
* can be used freely for any purpose. Any derived versions of this
|
|
* software must be clearly marked as such, and if the derived work is
|
|
* incompatible with the protocol description in the RFC file, it must be
|
|
* called by a name other than "ssh" or "Secure Shell".
|
|
*/
|
|
|
|
#include "includes.h"
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <netdb.h>
|
|
#include <pwd.h>
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
#include <stdarg.h>
|
|
|
|
#include "openbsd-compat/sys-queue.h"
|
|
|
|
#include "key.h" /* XXX for typedef */
|
|
#include "buffer.h" /* XXX for typedef */
|
|
#include "xmalloc.h"
|
|
#include "match.h"
|
|
#include "ssherr.h"
|
|
#include "log.h"
|
|
#include "canohost.h"
|
|
#include "packet.h"
|
|
#include "sshbuf.h"
|
|
#include "misc.h"
|
|
#include "channels.h"
|
|
#include "servconf.h"
|
|
#include "sshkey.h"
|
|
#include "auth-options.h"
|
|
#include "hostfile.h"
|
|
#include "auth.h"
|
|
|
|
/* Flags set authorized_keys flags */
|
|
int no_port_forwarding_flag = 0;
|
|
int no_agent_forwarding_flag = 0;
|
|
int no_x11_forwarding_flag = 0;
|
|
int no_pty_flag = 0;
|
|
int no_user_rc = 0;
|
|
int key_is_cert_authority = 0;
|
|
|
|
/* "command=" option. */
|
|
char *forced_command = NULL;
|
|
|
|
/* "environment=" options. */
|
|
struct envstring *custom_environment = NULL;
|
|
|
|
/* "tunnel=" option. */
|
|
int forced_tun_device = -1;
|
|
|
|
/* "principals=" option. */
|
|
char *authorized_principals = NULL;
|
|
|
|
extern ServerOptions options;
|
|
|
|
void
|
|
auth_clear_options(void)
|
|
{
|
|
no_agent_forwarding_flag = 0;
|
|
no_port_forwarding_flag = 0;
|
|
no_pty_flag = 0;
|
|
no_x11_forwarding_flag = 0;
|
|
no_user_rc = 0;
|
|
key_is_cert_authority = 0;
|
|
while (custom_environment) {
|
|
struct envstring *ce = custom_environment;
|
|
custom_environment = ce->next;
|
|
free(ce->s);
|
|
free(ce);
|
|
}
|
|
free(forced_command);
|
|
forced_command = NULL;
|
|
free(authorized_principals);
|
|
authorized_principals = NULL;
|
|
forced_tun_device = -1;
|
|
channel_clear_permitted_opens();
|
|
}
|
|
|
|
/*
|
|
* Match flag 'opt' in *optsp, and if allow_negate is set then also match
|
|
* 'no-opt'. Returns -1 if option not matched, 1 if option matches or 0
|
|
* if negated option matches.
|
|
* If the option or negated option matches, then *optsp is updated to
|
|
* point to the first character after the option and, if 'msg' is not NULL
|
|
* then a message based on it added via auth_debug_add().
|
|
*/
|
|
static int
|
|
match_flag(const char *opt, int allow_negate, char **optsp, const char *msg)
|
|
{
|
|
size_t opt_len = strlen(opt);
|
|
char *opts = *optsp;
|
|
int negate = 0;
|
|
|
|
if (allow_negate && strncasecmp(opts, "no-", 3) == 0) {
|
|
opts += 3;
|
|
negate = 1;
|
|
}
|
|
if (strncasecmp(opts, opt, opt_len) == 0) {
|
|
*optsp = opts + opt_len;
|
|
if (msg != NULL) {
|
|
auth_debug_add("%s %s.", msg,
|
|
negate ? "disabled" : "enabled");
|
|
}
|
|
return negate ? 0 : 1;
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* return 1 if access is granted, 0 if not.
|
|
* side effect: sets key option flags
|
|
*/
|
|
int
|
|
auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
|
|
{
|
|
struct ssh *ssh = active_state; /* XXX */
|
|
const char *cp;
|
|
int i, r;
|
|
|
|
/* reset options */
|
|
auth_clear_options();
|
|
|
|
if (!opts)
|
|
return 1;
|
|
|
|
while (*opts && *opts != ' ' && *opts != '\t') {
|
|
if ((r = match_flag("cert-authority", 0, &opts, NULL)) != -1) {
|
|
key_is_cert_authority = r;
|
|
goto next_option;
|
|
}
|
|
if ((r = match_flag("restrict", 0, &opts, NULL)) != -1) {
|
|
auth_debug_add("Key is restricted.");
|
|
no_port_forwarding_flag = 1;
|
|
no_agent_forwarding_flag = 1;
|
|
no_x11_forwarding_flag = 1;
|
|
no_pty_flag = 1;
|
|
no_user_rc = 1;
|
|
goto next_option;
|
|
}
|
|
if ((r = match_flag("port-forwarding", 1, &opts,
|
|
"Port forwarding")) != -1) {
|
|
no_port_forwarding_flag = r != 1;
|
|
goto next_option;
|
|
}
|
|
if ((r = match_flag("agent-forwarding", 1, &opts,
|
|
"Agent forwarding")) != -1) {
|
|
no_agent_forwarding_flag = r != 1;
|
|
goto next_option;
|
|
}
|
|
if ((r = match_flag("x11-forwarding", 1, &opts,
|
|
"X11 forwarding")) != -1) {
|
|
no_x11_forwarding_flag = r != 1;
|
|
goto next_option;
|
|
}
|
|
if ((r = match_flag("pty", 1, &opts,
|
|
"PTY allocation")) != -1) {
|
|
no_pty_flag = r != 1;
|
|
goto next_option;
|
|
}
|
|
if ((r = match_flag("user-rc", 1, &opts,
|
|
"User rc execution")) != -1) {
|
|
no_user_rc = r != 1;
|
|
goto next_option;
|
|
}
|
|
cp = "command=\"";
|
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
|
|
opts += strlen(cp);
|
|
free(forced_command);
|
|
forced_command = xmalloc(strlen(opts) + 1);
|
|
i = 0;
|
|
while (*opts) {
|
|
if (*opts == '"')
|
|
break;
|
|
if (*opts == '\\' && opts[1] == '"') {
|
|
opts += 2;
|
|
forced_command[i++] = '"';
|
|
continue;
|
|
}
|
|
forced_command[i++] = *opts++;
|
|
}
|
|
if (!*opts) {
|
|
debug("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
free(forced_command);
|
|
forced_command = NULL;
|
|
goto bad_option;
|
|
}
|
|
forced_command[i] = '\0';
|
|
auth_debug_add("Forced command.");
|
|
opts++;
|
|
goto next_option;
|
|
}
|
|
cp = "principals=\"";
|
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
|
|
opts += strlen(cp);
|
|
free(authorized_principals);
|
|
authorized_principals = xmalloc(strlen(opts) + 1);
|
|
i = 0;
|
|
while (*opts) {
|
|
if (*opts == '"')
|
|
break;
|
|
if (*opts == '\\' && opts[1] == '"') {
|
|
opts += 2;
|
|
authorized_principals[i++] = '"';
|
|
continue;
|
|
}
|
|
authorized_principals[i++] = *opts++;
|
|
}
|
|
if (!*opts) {
|
|
debug("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
free(authorized_principals);
|
|
authorized_principals = NULL;
|
|
goto bad_option;
|
|
}
|
|
authorized_principals[i] = '\0';
|
|
auth_debug_add("principals: %.900s",
|
|
authorized_principals);
|
|
opts++;
|
|
goto next_option;
|
|
}
|
|
cp = "environment=\"";
|
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
|
|
char *s;
|
|
struct envstring *new_envstring;
|
|
|
|
opts += strlen(cp);
|
|
s = xmalloc(strlen(opts) + 1);
|
|
i = 0;
|
|
while (*opts) {
|
|
if (*opts == '"')
|
|
break;
|
|
if (*opts == '\\' && opts[1] == '"') {
|
|
opts += 2;
|
|
s[i++] = '"';
|
|
continue;
|
|
}
|
|
s[i++] = *opts++;
|
|
}
|
|
if (!*opts) {
|
|
debug("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
free(s);
|
|
goto bad_option;
|
|
}
|
|
s[i] = '\0';
|
|
opts++;
|
|
if (options.permit_user_env) {
|
|
auth_debug_add("Adding to environment: "
|
|
"%.900s", s);
|
|
debug("Adding to environment: %.900s", s);
|
|
new_envstring = xcalloc(1,
|
|
sizeof(*new_envstring));
|
|
new_envstring->s = s;
|
|
new_envstring->next = custom_environment;
|
|
custom_environment = new_envstring;
|
|
s = NULL;
|
|
}
|
|
free(s);
|
|
goto next_option;
|
|
}
|
|
cp = "from=\"";
|
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
|
|
const char *remote_ip = ssh_remote_ipaddr(ssh);
|
|
const char *remote_host = auth_get_canonical_hostname(
|
|
ssh, options.use_dns);
|
|
char *patterns = xmalloc(strlen(opts) + 1);
|
|
|
|
opts += strlen(cp);
|
|
i = 0;
|
|
while (*opts) {
|
|
if (*opts == '"')
|
|
break;
|
|
if (*opts == '\\' && opts[1] == '"') {
|
|
opts += 2;
|
|
patterns[i++] = '"';
|
|
continue;
|
|
}
|
|
patterns[i++] = *opts++;
|
|
}
|
|
if (!*opts) {
|
|
debug("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
free(patterns);
|
|
goto bad_option;
|
|
}
|
|
patterns[i] = '\0';
|
|
opts++;
|
|
switch (match_host_and_ip(remote_host, remote_ip,
|
|
patterns)) {
|
|
case 1:
|
|
free(patterns);
|
|
/* Host name matches. */
|
|
goto next_option;
|
|
case -1:
|
|
debug("%.100s, line %lu: invalid criteria",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: "
|
|
"invalid criteria", file, linenum);
|
|
/* FALLTHROUGH */
|
|
case 0:
|
|
free(patterns);
|
|
logit("Authentication tried for %.100s with "
|
|
"correct key but not from a permitted "
|
|
"host (host=%.200s, ip=%.200s).",
|
|
pw->pw_name, remote_host, remote_ip);
|
|
auth_debug_add("Your host '%.200s' is not "
|
|
"permitted to use this key for login.",
|
|
remote_host);
|
|
break;
|
|
}
|
|
/* deny access */
|
|
return 0;
|
|
}
|
|
cp = "permitopen=\"";
|
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
|
|
char *host, *p;
|
|
int port;
|
|
char *patterns = xmalloc(strlen(opts) + 1);
|
|
|
|
opts += strlen(cp);
|
|
i = 0;
|
|
while (*opts) {
|
|
if (*opts == '"')
|
|
break;
|
|
if (*opts == '\\' && opts[1] == '"') {
|
|
opts += 2;
|
|
patterns[i++] = '"';
|
|
continue;
|
|
}
|
|
patterns[i++] = *opts++;
|
|
}
|
|
if (!*opts) {
|
|
debug("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: missing "
|
|
"end quote", file, linenum);
|
|
free(patterns);
|
|
goto bad_option;
|
|
}
|
|
patterns[i] = '\0';
|
|
opts++;
|
|
p = patterns;
|
|
/* XXX - add streamlocal support */
|
|
host = hpdelim(&p);
|
|
if (host == NULL || strlen(host) >= NI_MAXHOST) {
|
|
debug("%.100s, line %lu: Bad permitopen "
|
|
"specification <%.100s>", file, linenum,
|
|
patterns);
|
|
auth_debug_add("%.100s, line %lu: "
|
|
"Bad permitopen specification", file,
|
|
linenum);
|
|
free(patterns);
|
|
goto bad_option;
|
|
}
|
|
host = cleanhostname(host);
|
|
if (p == NULL || (port = permitopen_port(p)) < 0) {
|
|
debug("%.100s, line %lu: Bad permitopen port "
|
|
"<%.100s>", file, linenum, p ? p : "");
|
|
auth_debug_add("%.100s, line %lu: "
|
|
"Bad permitopen port", file, linenum);
|
|
free(patterns);
|
|
goto bad_option;
|
|
}
|
|
if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0)
|
|
channel_add_permitted_opens(host, port);
|
|
free(patterns);
|
|
goto next_option;
|
|
}
|
|
cp = "tunnel=\"";
|
|
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
|
|
char *tun = NULL;
|
|
opts += strlen(cp);
|
|
tun = xmalloc(strlen(opts) + 1);
|
|
i = 0;
|
|
while (*opts) {
|
|
if (*opts == '"')
|
|
break;
|
|
tun[i++] = *opts++;
|
|
}
|
|
if (!*opts) {
|
|
debug("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: missing end quote",
|
|
file, linenum);
|
|
free(tun);
|
|
forced_tun_device = -1;
|
|
goto bad_option;
|
|
}
|
|
tun[i] = '\0';
|
|
forced_tun_device = a2tun(tun, NULL);
|
|
free(tun);
|
|
if (forced_tun_device == SSH_TUNID_ERR) {
|
|
debug("%.100s, line %lu: invalid tun device",
|
|
file, linenum);
|
|
auth_debug_add("%.100s, line %lu: invalid tun device",
|
|
file, linenum);
|
|
forced_tun_device = -1;
|
|
goto bad_option;
|
|
}
|
|
auth_debug_add("Forced tun device: %d", forced_tun_device);
|
|
opts++;
|
|
goto next_option;
|
|
}
|
|
next_option:
|
|
/*
|
|
* Skip the comma, and move to the next option
|
|
* (or break out if there are no more).
|
|
*/
|
|
if (!*opts)
|
|
fatal("Bugs in auth-options.c option processing.");
|
|
if (*opts == ' ' || *opts == '\t')
|
|
break; /* End of options. */
|
|
if (*opts != ',')
|
|
goto bad_option;
|
|
opts++;
|
|
/* Process the next option. */
|
|
}
|
|
|
|
/* grant access */
|
|
return 1;
|
|
|
|
bad_option:
|
|
logit("Bad options in %.100s file, line %lu: %.50s",
|
|
file, linenum, opts);
|
|
auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
|
|
file, linenum, opts);
|
|
|
|
/* deny access */
|
|
return 0;
|
|
}
|
|
|
|
#define OPTIONS_CRITICAL 1
|
|
#define OPTIONS_EXTENSIONS 2
|
|
static int
|
|
parse_option_list(struct sshbuf *oblob, struct passwd *pw,
|
|
u_int which, int crit,
|
|
int *cert_no_port_forwarding_flag,
|
|
int *cert_no_agent_forwarding_flag,
|
|
int *cert_no_x11_forwarding_flag,
|
|
int *cert_no_pty_flag,
|
|
int *cert_no_user_rc,
|
|
char **cert_forced_command,
|
|
int *cert_source_address_done)
|
|
{
|
|
struct ssh *ssh = active_state; /* XXX */
|
|
char *command, *allowed;
|
|
const char *remote_ip;
|
|
char *name = NULL;
|
|
struct sshbuf *c = NULL, *data = NULL;
|
|
int r, ret = -1, result, found;
|
|
|
|
if ((c = sshbuf_fromb(oblob)) == NULL) {
|
|
error("%s: sshbuf_fromb failed", __func__);
|
|
goto out;
|
|
}
|
|
|
|
while (sshbuf_len(c) > 0) {
|
|
sshbuf_free(data);
|
|
data = NULL;
|
|
if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 ||
|
|
(r = sshbuf_froms(c, &data)) != 0) {
|
|
error("Unable to parse certificate options: %s",
|
|
ssh_err(r));
|
|
goto out;
|
|
}
|
|
debug3("found certificate option \"%.100s\" len %zu",
|
|
name, sshbuf_len(data));
|
|
found = 0;
|
|
if ((which & OPTIONS_EXTENSIONS) != 0) {
|
|
if (strcmp(name, "permit-X11-forwarding") == 0) {
|
|
*cert_no_x11_forwarding_flag = 0;
|
|
found = 1;
|
|
} else if (strcmp(name,
|
|
"permit-agent-forwarding") == 0) {
|
|
*cert_no_agent_forwarding_flag = 0;
|
|
found = 1;
|
|
} else if (strcmp(name,
|
|
"permit-port-forwarding") == 0) {
|
|
*cert_no_port_forwarding_flag = 0;
|
|
found = 1;
|
|
} else if (strcmp(name, "permit-pty") == 0) {
|
|
*cert_no_pty_flag = 0;
|
|
found = 1;
|
|
} else if (strcmp(name, "permit-user-rc") == 0) {
|
|
*cert_no_user_rc = 0;
|
|
found = 1;
|
|
}
|
|
}
|
|
if (!found && (which & OPTIONS_CRITICAL) != 0) {
|
|
if (strcmp(name, "force-command") == 0) {
|
|
if ((r = sshbuf_get_cstring(data, &command,
|
|
NULL)) != 0) {
|
|
error("Unable to parse \"%s\" "
|
|
"section: %s", name, ssh_err(r));
|
|
goto out;
|
|
}
|
|
if (*cert_forced_command != NULL) {
|
|
error("Certificate has multiple "
|
|
"force-command options");
|
|
free(command);
|
|
goto out;
|
|
}
|
|
*cert_forced_command = command;
|
|
found = 1;
|
|
}
|
|
if (strcmp(name, "source-address") == 0) {
|
|
if ((r = sshbuf_get_cstring(data, &allowed,
|
|
NULL)) != 0) {
|
|
error("Unable to parse \"%s\" "
|
|
"section: %s", name, ssh_err(r));
|
|
goto out;
|
|
}
|
|
if ((*cert_source_address_done)++) {
|
|
error("Certificate has multiple "
|
|
"source-address options");
|
|
free(allowed);
|
|
goto out;
|
|
}
|
|
remote_ip = ssh_remote_ipaddr(ssh);
|
|
result = addr_match_cidr_list(remote_ip,
|
|
allowed);
|
|
free(allowed);
|
|
switch (result) {
|
|
case 1:
|
|
/* accepted */
|
|
break;
|
|
case 0:
|
|
/* no match */
|
|
logit("Authentication tried for %.100s "
|
|
"with valid certificate but not "
|
|
"from a permitted host "
|
|
"(ip=%.200s).", pw->pw_name,
|
|
remote_ip);
|
|
auth_debug_add("Your address '%.200s' "
|
|
"is not permitted to use this "
|
|
"certificate for login.",
|
|
remote_ip);
|
|
goto out;
|
|
case -1:
|
|
default:
|
|
error("Certificate source-address "
|
|
"contents invalid");
|
|
goto out;
|
|
}
|
|
found = 1;
|
|
}
|
|
}
|
|
|
|
if (!found) {
|
|
if (crit) {
|
|
error("Certificate critical option \"%s\" "
|
|
"is not supported", name);
|
|
goto out;
|
|
} else {
|
|
logit("Certificate extension \"%s\" "
|
|
"is not supported", name);
|
|
}
|
|
} else if (sshbuf_len(data) != 0) {
|
|
error("Certificate option \"%s\" corrupt "
|
|
"(extra data)", name);
|
|
goto out;
|
|
}
|
|
free(name);
|
|
name = NULL;
|
|
}
|
|
/* successfully parsed all options */
|
|
ret = 0;
|
|
|
|
out:
|
|
if (ret != 0 &&
|
|
cert_forced_command != NULL &&
|
|
*cert_forced_command != NULL) {
|
|
free(*cert_forced_command);
|
|
*cert_forced_command = NULL;
|
|
}
|
|
free(name);
|
|
sshbuf_free(data);
|
|
sshbuf_free(c);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Set options from critical certificate options. These supersede user key
|
|
* options so this must be called after auth_parse_options().
|
|
*/
|
|
int
|
|
auth_cert_options(struct sshkey *k, struct passwd *pw, const char **reason)
|
|
{
|
|
int cert_no_port_forwarding_flag = 1;
|
|
int cert_no_agent_forwarding_flag = 1;
|
|
int cert_no_x11_forwarding_flag = 1;
|
|
int cert_no_pty_flag = 1;
|
|
int cert_no_user_rc = 1;
|
|
char *cert_forced_command = NULL;
|
|
int cert_source_address_done = 0;
|
|
|
|
*reason = "invalid certificate options";
|
|
|
|
/* Separate options and extensions for v01 certs */
|
|
if (parse_option_list(k->cert->critical, pw,
|
|
OPTIONS_CRITICAL, 1, NULL, NULL, NULL, NULL, NULL,
|
|
&cert_forced_command,
|
|
&cert_source_address_done) == -1)
|
|
return -1;
|
|
if (parse_option_list(k->cert->extensions, pw,
|
|
OPTIONS_EXTENSIONS, 0,
|
|
&cert_no_port_forwarding_flag,
|
|
&cert_no_agent_forwarding_flag,
|
|
&cert_no_x11_forwarding_flag,
|
|
&cert_no_pty_flag,
|
|
&cert_no_user_rc,
|
|
NULL, NULL) == -1)
|
|
return -1;
|
|
|
|
no_port_forwarding_flag |= cert_no_port_forwarding_flag;
|
|
no_agent_forwarding_flag |= cert_no_agent_forwarding_flag;
|
|
no_x11_forwarding_flag |= cert_no_x11_forwarding_flag;
|
|
no_pty_flag |= cert_no_pty_flag;
|
|
no_user_rc |= cert_no_user_rc;
|
|
/*
|
|
* Only permit both CA and key option forced-command if they match.
|
|
* Otherwise refuse the certificate.
|
|
*/
|
|
if (cert_forced_command != NULL && forced_command != NULL) {
|
|
if (strcmp(forced_command, cert_forced_command) == 0) {
|
|
free(forced_command);
|
|
forced_command = cert_forced_command;
|
|
} else {
|
|
*reason = "certificate and key options forced command "
|
|
"do not match";
|
|
free(cert_forced_command);
|
|
return -1;
|
|
}
|
|
} else if (cert_forced_command != NULL)
|
|
forced_command = cert_forced_command;
|
|
/* success */
|
|
*reason = NULL;
|
|
return 0;
|
|
}
|
|
|