115 lines
3.7 KiB
C
115 lines
3.7 KiB
C
/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Rhosts or /etc/hosts.equiv authentication combined with RSA host
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* authentication.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*/
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#include "includes.h"
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RCSID("$OpenBSD: auth-rh-rsa.c,v 1.16 2000/09/07 21:13:36 markus Exp $");
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RCSID("$FreeBSD$");
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#include "packet.h"
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#include "ssh.h"
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#include "xmalloc.h"
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#include "uidswap.h"
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#include "servconf.h"
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#include <openssl/rsa.h>
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#include <openssl/dsa.h>
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#include "key.h"
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#include "hostfile.h"
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/*
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* Tries to authenticate the user using the .rhosts file and the host using
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* its host key. Returns true if authentication succeeds.
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*/
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int
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auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key)
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{
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extern ServerOptions options;
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const char *canonical_hostname;
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HostStatus host_status;
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Key *client_key, *found;
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debug("Trying rhosts with RSA host authentication for %.100s", client_user);
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if (client_host_key == NULL)
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return 0;
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/* Check if we would accept it using rhosts authentication. */
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if (!auth_rhosts(pw, client_user))
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return 0;
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canonical_hostname = get_canonical_hostname();
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debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname);
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/* wrap the RSA key into a 'generic' key */
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client_key = key_new(KEY_RSA);
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BN_copy(client_key->rsa->e, client_host_key->e);
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BN_copy(client_key->rsa->n, client_host_key->n);
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found = key_new(KEY_RSA);
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/* Check if we know the host and its host key. */
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host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname,
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client_key, found);
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/* Check user host file unless ignored. */
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if (host_status != HOST_OK && !options.ignore_user_known_hosts) {
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struct stat st;
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char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid);
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/*
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* Check file permissions of SSH_USER_HOSTFILE, auth_rsa()
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* did already check pw->pw_dir, but there is a race XXX
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*/
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if (options.strict_modes &&
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(stat(user_hostfile, &st) == 0) &&
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((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
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(st.st_mode & 022) != 0)) {
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log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s",
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pw->pw_name, user_hostfile);
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} else {
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/* XXX race between stat and the following open() */
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temporarily_use_uid(pw->pw_uid);
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host_status = check_host_in_hostfile(user_hostfile, canonical_hostname,
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client_key, found);
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restore_uid();
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}
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xfree(user_hostfile);
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}
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key_free(client_key);
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key_free(found);
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if (host_status != HOST_OK) {
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debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
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packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
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return 0;
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}
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/* A matching host key was found and is known. */
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/* Perform the challenge-response dialog with the client for the host key. */
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if (!auth_rsa_challenge_dialog(client_host_key)) {
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log("Client on %.800s failed to respond correctly to host authentication.",
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canonical_hostname);
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return 0;
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}
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/*
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* We have authenticated the user using .rhosts or /etc/hosts.equiv,
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* and the host using RSA. We accept the authentication.
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*/
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verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
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pw->pw_name, client_user, canonical_hostname);
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packet_send_debug("Rhosts with RSA host authentication accepted.");
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return 1;
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}
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