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openssh/auth-options.c

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/* $OpenBSD: auth-options.c,v 1.40 2006/08/03 03:34:41 deraadt 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 "xmalloc.h"
#include "match.h"
#include "log.h"
#include "canohost.h"
#include "buffer.h"
#include "channels.h"
#include "auth-options.h"
#include "servconf.h"
#include "misc.h"
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.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;
/* "command=" option. */
char *forced_command = NULL;
/* "environment=" options. */
struct envstring *custom_environment = NULL;
/* "tunnel=" option. */
int forced_tun_device = -1;
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;
while (custom_environment) {
struct envstring *ce = custom_environment;
custom_environment = ce->next;
xfree(ce->s);
xfree(ce);
}
if (forced_command) {
xfree(forced_command);
forced_command = NULL;
}
forced_tun_device = -1;
channel_clear_permitted_opens();
auth_debug_reset();
}
/*
* 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)
{
const char *cp;
int i;
/* reset options */
auth_clear_options();
if (!opts)
return 1;
while (*opts && *opts != ' ' && *opts != '\t') {
cp = "no-port-forwarding";
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
auth_debug_add("Port forwarding disabled.");
no_port_forwarding_flag = 1;
opts += strlen(cp);
goto next_option;
}
cp = "no-agent-forwarding";
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
auth_debug_add("Agent forwarding disabled.");
no_agent_forwarding_flag = 1;
opts += strlen(cp);
goto next_option;
}
cp = "no-X11-forwarding";
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
auth_debug_add("X11 forwarding disabled.");
no_x11_forwarding_flag = 1;
opts += strlen(cp);
goto next_option;
}
cp = "no-pty";
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
auth_debug_add("Pty allocation disabled.");
no_pty_flag = 1;
opts += strlen(cp);
goto next_option;
}
cp = "command=\"";
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
opts += strlen(cp);
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);
xfree(forced_command);
forced_command = NULL;
goto bad_option;
}
forced_command[i] = '\0';
auth_debug_add("Forced command: %.900s", forced_command);
opts++;
goto next_option;
}
cp = "environment=\"";
if (options.permit_user_env &&
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);
xfree(s);
goto bad_option;
}
s[i] = '\0';
auth_debug_add("Adding to environment: %.900s", s);
debug("Adding to environment: %.900s", s);
opts++;
new_envstring = xmalloc(sizeof(struct envstring));
new_envstring->s = s;
new_envstring->next = custom_environment;
custom_environment = new_envstring;
goto next_option;
}
cp = "from=\"";
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
const char *remote_ip = get_remote_ipaddr();
const char *remote_host = get_canonical_hostname(
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);
xfree(patterns);
goto bad_option;
}
patterns[i] = '\0';
opts++;
if (match_host_and_ip(remote_host, remote_ip,
patterns) != 1) {
xfree(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);
/* deny access */
return 0;
}
xfree(patterns);
/* Host name matches. */
goto next_option;
}
cp = "permitopen=\"";
if (strncasecmp(opts, cp, strlen(cp)) == 0) {
char *host, *p;
u_short 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);
xfree(patterns);
goto bad_option;
}
patterns[i] = '\0';
opts++;
p = patterns;
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);
xfree(patterns);
goto bad_option;
}
host = cleanhostname(host);
if (p == NULL || (port = a2port(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);
xfree(patterns);
goto bad_option;
}
if (options.allow_tcp_forwarding)
channel_add_permitted_opens(host, port);
xfree(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);
xfree(tun);
forced_tun_device = -1;
goto bad_option;
}
tun[i] = '\0';
forced_tun_device = a2tun(tun, NULL);
xfree(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. */
}
if (!use_privsep)
auth_debug_send();
/* 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);
if (!use_privsep)
auth_debug_send();
/* deny access */
return 0;
}
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