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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
* Rhosts or /etc/hosts.equiv authentication combined with RSA host
* authentication.
*
* 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-rh-rsa.c,v 1.21 2001/01/21 19:05:42 markus Exp $");
#include "packet.h"
#include "xmalloc.h"
#include "uidswap.h"
#include "log.h"
#include "servconf.h"
#include "key.h"
#include "hostfile.h"
#include "pathnames.h"
#include "auth.h"
#include "tildexpand.h"
#include "canohost.h"
/*
* Tries to authenticate the user using the .rhosts file and the host using
* its host key. Returns true if authentication succeeds.
*/
int
auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key)
{
extern ServerOptions options;
const char *canonical_hostname;
HostStatus host_status;
Key *client_key, *found;
debug("Trying rhosts with RSA host authentication for client user %.100s", client_user);
if (pw == NULL || client_host_key == NULL)
return 0;
/* Check if we would accept it using rhosts authentication. */
if (!auth_rhosts(pw, client_user))
return 0;
canonical_hostname = get_canonical_hostname();
debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname);
/* wrap the RSA key into a 'generic' key */
client_key = key_new(KEY_RSA1);
BN_copy(client_key->rsa->e, client_host_key->e);
BN_copy(client_key->rsa->n, client_host_key->n);
found = key_new(KEY_RSA1);
/* Check if we know the host and its host key. */
host_status = check_host_in_hostfile(_PATH_SSH_SYSTEM_HOSTFILE, canonical_hostname,
client_key, found, NULL);
/* Check user host file unless ignored. */
if (host_status != HOST_OK && !options.ignore_user_known_hosts) {
struct stat st;
char *user_hostfile = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid);
/*
* Check file permissions of _PATH_SSH_USER_HOSTFILE, auth_rsa()
* did already check pw->pw_dir, but there is a race XXX
*/
if (options.strict_modes &&
(stat(user_hostfile, &st) == 0) &&
((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
(st.st_mode & 022) != 0)) {
log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s",
pw->pw_name, user_hostfile);
} else {
/* XXX race between stat and the following open() */
temporarily_use_uid(pw->pw_uid);
host_status = check_host_in_hostfile(user_hostfile, canonical_hostname,
client_key, found, NULL);
restore_uid();
}
xfree(user_hostfile);
}
key_free(client_key);
key_free(found);
if (host_status != HOST_OK) {
debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
return 0;
}
/* A matching host key was found and is known. */
/* Perform the challenge-response dialog with the client for the host key. */
if (!auth_rsa_challenge_dialog(client_host_key)) {
log("Client on %.800s failed to respond correctly to host authentication.",
canonical_hostname);
return 0;
}
/*
* We have authenticated the user using .rhosts or /etc/hosts.equiv,
* and the host using RSA. We accept the authentication.
*/
verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
pw->pw_name, client_user, canonical_hostname);
packet_send_debug("Rhosts with RSA host authentication accepted.");
return 1;
}
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