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/*
auth-rh-rsa.c
Author: Tatu Ylonen <ylo@cs.hut.fi>
Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
All rights reserved
Created: Sun May 7 03:08:06 1995 ylo
Rhosts or /etc/hosts.equiv authentication combined with RSA host
authentication.
*/
#include "includes.h"
RCSID("$Id: auth-rh-rsa.c,v 1.3 1999/11/12 00:33:04 damien Exp $");
#include "packet.h"
#include "ssh.h"
#include "xmalloc.h"
#include "uidswap.h"
#include "servconf.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,
unsigned int client_host_key_bits,
BIGNUM *client_host_key_e, BIGNUM *client_host_key_n)
{
extern ServerOptions options;
const char *canonical_hostname;
HostStatus host_status;
BIGNUM *ke, *kn;
debug("Trying rhosts with RSA host authentication for %.100s", client_user);
/* Check if we would accept it using rhosts authentication. */
if (!auth_rhosts(pw, client_user, options.ignore_rhosts, options.strict_modes))
return 0;
canonical_hostname = get_canonical_hostname();
debug("Rhosts RSA authentication: canonical host %.900s",
canonical_hostname);
/* Check if we know the host and its host key. */
/* Check system-wide host file. */
ke = BN_new();
kn = BN_new();
host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname,
client_host_key_bits, client_host_key_e,
client_host_key_n, ke, kn);
/* 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(SSH_USER_HOSTFILE, pw->pw_uid);
/* Check file permissions of 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_host_key_bits, client_host_key_e,
client_host_key_n, ke, kn);
restore_uid();
}
xfree(user_hostfile);
}
BN_free(ke);
BN_free(kn);
if (host_status != HOST_OK) {
/* The host key was not found. */
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_bits,
client_host_key_e, client_host_key_n))
{
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. */
log("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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