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/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* RSA-based authentication. This code determines whether to admit a login
* based on RSA authentication. This file also contains functions to check
* validity of the host key.
*
* 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"
RCSID("$OpenBSD: auth-options.c,v 1.6 2000/11/15 22:31:36 markus Exp $");
#include "ssh.h"
#include "packet.h"
#include "xmalloc.h"
#include "match.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;
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;
}
}
/* return 1 if access is granted, 0 if not. side effect: sets key option flags */
int
auth_parse_options(struct passwd *pw, char *options, unsigned long linenum)
{
const char *cp;
if (!options)
return 1;
/* reset options */
auth_clear_options();
while (*options && *options != ' ' && *options != '\t') {
cp = "no-port-forwarding";
if (strncasecmp(options, cp, strlen(cp)) == 0) {
packet_send_debug("Port forwarding disabled.");
no_port_forwarding_flag = 1;
options += strlen(cp);
goto next_option;
}
cp = "no-agent-forwarding";
if (strncasecmp(options, cp, strlen(cp)) == 0) {
packet_send_debug("Agent forwarding disabled.");
no_agent_forwarding_flag = 1;
options += strlen(cp);
goto next_option;
}
cp = "no-X11-forwarding";
if (strncasecmp(options, cp, strlen(cp)) == 0) {
packet_send_debug("X11 forwarding disabled.");
no_x11_forwarding_flag = 1;
options += strlen(cp);
goto next_option;
}
cp = "no-pty";
if (strncasecmp(options, cp, strlen(cp)) == 0) {
packet_send_debug("Pty allocation disabled.");
no_pty_flag = 1;
options += strlen(cp);
goto next_option;
}
cp = "command=\"";
if (strncasecmp(options, cp, strlen(cp)) == 0) {
int i;
options += strlen(cp);
forced_command = xmalloc(strlen(options) + 1);
i = 0;
while (*options) {
if (*options == '"')
break;
if (*options == '\\' && options[1] == '"') {
options += 2;
forced_command[i++] = '"';
continue;
}
forced_command[i++] = *options++;
}
if (!*options) {
debug("%.100s, line %lu: missing end quote",
SSH_USER_PERMITTED_KEYS, linenum);
packet_send_debug("%.100s, line %lu: missing end quote",
SSH_USER_PERMITTED_KEYS, linenum);
continue;
}
forced_command[i] = 0;
packet_send_debug("Forced command: %.900s", forced_command);
options++;
goto next_option;
}
cp = "environment=\"";
if (strncasecmp(options, cp, strlen(cp)) == 0) {
int i;
char *s;
struct envstring *new_envstring;
options += strlen(cp);
s = xmalloc(strlen(options) + 1);
i = 0;
while (*options) {
if (*options == '"')
break;
if (*options == '\\' && options[1] == '"') {
options += 2;
s[i++] = '"';
continue;
}
s[i++] = *options++;
}
if (!*options) {
debug("%.100s, line %lu: missing end quote",
SSH_USER_PERMITTED_KEYS, linenum);
packet_send_debug("%.100s, line %lu: missing end quote",
SSH_USER_PERMITTED_KEYS, linenum);
continue;
}
s[i] = 0;
packet_send_debug("Adding to environment: %.900s", s);
debug("Adding to environment: %.900s", s);
options++;
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(options, cp, strlen(cp)) == 0) {
int mname, mip;
char *patterns = xmalloc(strlen(options) + 1);
int i;
options += strlen(cp);
i = 0;
while (*options) {
if (*options == '"')
break;
if (*options == '\\' && options[1] == '"') {
options += 2;
patterns[i++] = '"';
continue;
}
patterns[i++] = *options++;
}
if (!*options) {
debug("%.100s, line %lu: missing end quote",
SSH_USER_PERMITTED_KEYS, linenum);
packet_send_debug("%.100s, line %lu: missing end quote",
SSH_USER_PERMITTED_KEYS, linenum);
continue;
}
patterns[i] = 0;
options++;
/*
* Deny access if we get a negative
* match for the hostname or the ip
* or if we get not match at all
*/
mname = match_hostname(get_canonical_hostname(),
patterns, strlen(patterns));
mip = match_hostname(get_remote_ipaddr(),
patterns, strlen(patterns));
xfree(patterns);
if (mname == -1 || mip == -1 ||
(mname != 1 && mip != 1)) {
log("Authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).",
pw->pw_name, get_canonical_hostname(),
get_remote_ipaddr());
packet_send_debug("Your host '%.200s' is not permitted to use this key for login.",
get_canonical_hostname());
/* deny access */
return 0;
}
/* Host name matches. */
goto next_option;
}
next_option:
/*
* Skip the comma, and move to the next option
* (or break out if there are no more).
*/
if (!*options)
fatal("Bugs in auth-options.c option processing.");
if (*options == ' ' || *options == '\t')
break; /* End of options. */
if (*options != ',')
goto bad_option;
options++;
/* Process the next option. */
}
/* grant access */
return 1;
bad_option:
log("Bad options in %.100s file, line %lu: %.50s",
SSH_USER_PERMITTED_KEYS, linenum, options);
packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
SSH_USER_PERMITTED_KEYS, linenum, options);
/* deny access */
return 0;
}
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