554 lines
14 KiB
C
554 lines
14 KiB
C
/* $NetBSD: authfd.c,v 1.1.1.1 2000/09/28 22:09:44 thorpej Exp $ */
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/*
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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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* Functions for connecting the local authentication agent.
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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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* SSH2 implementation,
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* from OpenBSD: authfd.c,v 1.28 2000/09/21 11:07:50 markus Exp */
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: authfd.c,v 1.1.1.1 2000/09/28 22:09:44 thorpej Exp $");
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#endif
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#include "includes.h"
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#include "ssh.h"
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#include "rsa.h"
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#include "buffer.h"
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#include "bufaux.h"
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#include "xmalloc.h"
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#include "getput.h"
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#include <openssl/rsa.h>
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#include <openssl/dsa.h>
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#include <openssl/evp.h>
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#include "key.h"
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#include "authfd.h"
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#include "kex.h"
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#include "dsa.h"
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#include "compat.h"
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/* helper */
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int decode_reply(int type);
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/* Returns the number of the authentication fd, or -1 if there is none. */
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int
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ssh_get_authentication_socket()
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{
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const char *authsocket;
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int sock, len;
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struct sockaddr_un sunaddr;
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authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
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if (!authsocket)
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return -1;
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sunaddr.sun_family = AF_UNIX;
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strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
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sunaddr.sun_len = len = SUN_LEN(&sunaddr)+1;
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sock = socket(AF_UNIX, SOCK_STREAM, 0);
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if (sock < 0)
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return -1;
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/* close on exec */
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if (fcntl(sock, F_SETFD, 1) == -1) {
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close(sock);
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return -1;
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}
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if (connect(sock, (struct sockaddr *) & sunaddr, len) < 0) {
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close(sock);
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return -1;
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}
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return sock;
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}
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static int
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ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
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{
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int l, len;
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char buf[1024];
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/* Get the length of the message, and format it in the buffer. */
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len = buffer_len(request);
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PUT_32BIT(buf, len);
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/* Send the length and then the packet to the agent. */
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if (atomic_write(auth->fd, buf, 4) != 4 ||
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atomic_write(auth->fd, buffer_ptr(request),
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buffer_len(request)) != buffer_len(request)) {
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error("Error writing to authentication socket.");
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return 0;
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}
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/*
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* Wait for response from the agent. First read the length of the
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* response packet.
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*/
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len = 4;
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while (len > 0) {
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l = read(auth->fd, buf + 4 - len, len);
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if (l <= 0) {
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error("Error reading response length from authentication socket.");
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return 0;
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}
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len -= l;
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}
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/* Extract the length, and check it for sanity. */
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len = GET_32BIT(buf);
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if (len > 256 * 1024)
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fatal("Authentication response too long: %d", len);
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/* Read the rest of the response in to the buffer. */
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buffer_clear(reply);
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while (len > 0) {
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l = len;
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if (l > sizeof(buf))
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l = sizeof(buf);
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l = read(auth->fd, buf, l);
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if (l <= 0) {
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error("Error reading response from authentication socket.");
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return 0;
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}
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buffer_append(reply, (char *) buf, l);
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len -= l;
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}
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return 1;
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}
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/*
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* Closes the agent socket if it should be closed (depends on how it was
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* obtained). The argument must have been returned by
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* ssh_get_authentication_socket().
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*/
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void
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ssh_close_authentication_socket(int sock)
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{
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if (getenv(SSH_AUTHSOCKET_ENV_NAME))
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close(sock);
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}
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/*
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* Opens and connects a private socket for communication with the
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* authentication agent. Returns the file descriptor (which must be
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* shut down and closed by the caller when no longer needed).
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* Returns NULL if an error occurred and the connection could not be
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* opened.
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*/
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AuthenticationConnection *
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ssh_get_authentication_connection()
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{
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AuthenticationConnection *auth;
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int sock;
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sock = ssh_get_authentication_socket();
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/*
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* Fail if we couldn't obtain a connection. This happens if we
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* exited due to a timeout.
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*/
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if (sock < 0)
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return NULL;
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auth = xmalloc(sizeof(*auth));
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auth->fd = sock;
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buffer_init(&auth->identities);
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auth->howmany = 0;
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return auth;
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}
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/*
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* Closes the connection to the authentication agent and frees any associated
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* memory.
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*/
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void
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ssh_close_authentication_connection(AuthenticationConnection *auth)
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{
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buffer_free(&auth->identities);
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close(auth->fd);
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xfree(auth);
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}
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/*
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* Returns the first authentication identity held by the agent.
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*/
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Key *
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ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
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{
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int type, code1 = 0, code2 = 0;
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Buffer request;
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switch(version){
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case 1:
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code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
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code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
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break;
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case 2:
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code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
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code2 = SSH2_AGENT_IDENTITIES_ANSWER;
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break;
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default:
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return NULL;
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}
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/*
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* Send a message to the agent requesting for a list of the
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* identities it can represent.
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*/
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buffer_init(&request);
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buffer_put_char(&request, code1);
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buffer_clear(&auth->identities);
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if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
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buffer_free(&request);
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return NULL;
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}
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buffer_free(&request);
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/* Get message type, and verify that we got a proper answer. */
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type = buffer_get_char(&auth->identities);
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if (type == SSH_AGENT_FAILURE) {
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return NULL;
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} else if (type != code2) {
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fatal("Bad authentication reply message type: %d", type);
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}
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/* Get the number of entries in the response and check it for sanity. */
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auth->howmany = buffer_get_int(&auth->identities);
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if (auth->howmany > 1024)
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fatal("Too many identities in authentication reply: %d\n",
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auth->howmany);
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/* Return the first entry (if any). */
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return ssh_get_next_identity(auth, comment, version);
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}
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Key *
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ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
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{
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unsigned int bits;
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unsigned char *blob;
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unsigned int blen;
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Key *key = NULL;
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/* Return failure if no more entries. */
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if (auth->howmany <= 0)
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return NULL;
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/*
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* Get the next entry from the packet. These will abort with a fatal
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* error if the packet is too short or contains corrupt data.
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*/
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switch(version){
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case 1:
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key = key_new(KEY_RSA);
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bits = buffer_get_int(&auth->identities);
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buffer_get_bignum(&auth->identities, key->rsa->e);
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buffer_get_bignum(&auth->identities, key->rsa->n);
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*comment = buffer_get_string(&auth->identities, NULL);
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if (bits != BN_num_bits(key->rsa->n))
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log("Warning: identity keysize mismatch: actual %d, announced %u",
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BN_num_bits(key->rsa->n), bits);
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break;
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case 2:
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blob = buffer_get_string(&auth->identities, &blen);
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*comment = buffer_get_string(&auth->identities, NULL);
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key = dsa_key_from_blob(blob, blen);
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xfree(blob);
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break;
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default:
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return NULL;
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break;
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}
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/* Decrement the number of remaining entries. */
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auth->howmany--;
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return key;
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}
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/*
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* Generates a random challenge, sends it to the agent, and waits for
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* response from the agent. Returns true (non-zero) if the agent gave the
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* correct answer, zero otherwise. Response type selects the style of
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* response desired, with 0 corresponding to protocol version 1.0 (no longer
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* supported) and 1 corresponding to protocol version 1.1.
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*/
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int
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ssh_decrypt_challenge(AuthenticationConnection *auth,
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Key* key, BIGNUM *challenge,
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unsigned char session_id[16],
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unsigned int response_type,
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unsigned char response[16])
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{
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Buffer buffer;
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int success = 0;
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int i;
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int type;
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if (key->type != KEY_RSA)
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return 0;
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if (response_type == 0) {
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log("Compatibility with ssh protocol version 1.0 no longer supported.");
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return 0;
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}
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buffer_init(&buffer);
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buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
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buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
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buffer_put_bignum(&buffer, key->rsa->e);
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buffer_put_bignum(&buffer, key->rsa->n);
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buffer_put_bignum(&buffer, challenge);
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buffer_append(&buffer, (char *) session_id, 16);
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buffer_put_int(&buffer, response_type);
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if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
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buffer_free(&buffer);
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return 0;
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}
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type = buffer_get_char(&buffer);
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if (type == SSH_AGENT_FAILURE) {
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log("Agent admitted failure to authenticate using the key.");
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} else if (type != SSH_AGENT_RSA_RESPONSE) {
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fatal("Bad authentication response: %d", type);
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} else {
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success = 1;
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/*
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* Get the response from the packet. This will abort with a
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* fatal error if the packet is corrupt.
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*/
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for (i = 0; i < 16; i++)
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response[i] = buffer_get_char(&buffer);
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}
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buffer_free(&buffer);
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return success;
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}
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/* ask agent to sign data, returns -1 on error, 0 on success */
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int
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ssh_agent_sign(AuthenticationConnection *auth,
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Key *key,
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unsigned char **sigp, int *lenp,
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unsigned char *data, int datalen)
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{
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extern int datafellows;
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Buffer msg;
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unsigned char *blob;
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unsigned int blen;
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int type, flags = 0;
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int ret = -1;
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if (dsa_make_key_blob(key, &blob, &blen) == 0)
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return -1;
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if (datafellows & SSH_BUG_SIGBLOB)
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flags = SSH_AGENT_OLD_SIGNATURE;
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buffer_init(&msg);
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buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
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buffer_put_string(&msg, blob, blen);
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buffer_put_string(&msg, data, datalen);
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buffer_put_int(&msg, flags);
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xfree(blob);
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if (ssh_request_reply(auth, &msg, &msg) == 0) {
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buffer_free(&msg);
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return -1;
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}
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type = buffer_get_char(&msg);
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if (type == SSH_AGENT_FAILURE) {
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log("Agent admitted failure to sign using the key.");
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} else if (type != SSH2_AGENT_SIGN_RESPONSE) {
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fatal("Bad authentication response: %d", type);
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} else {
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ret = 0;
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*sigp = buffer_get_string(&msg, lenp);
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}
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buffer_free(&msg);
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return ret;
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}
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/* Encode key for a message to the agent. */
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static void
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ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment)
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{
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buffer_clear(b);
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buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
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buffer_put_int(b, BN_num_bits(key->n));
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buffer_put_bignum(b, key->n);
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buffer_put_bignum(b, key->e);
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buffer_put_bignum(b, key->d);
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/* To keep within the protocol: p < q for ssh. in SSL p > q */
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buffer_put_bignum(b, key->iqmp); /* ssh key->u */
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buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
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buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
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buffer_put_string(b, comment, strlen(comment));
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}
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static void
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ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment)
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{
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buffer_clear(b);
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buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
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buffer_put_cstring(b, KEX_DSS);
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buffer_put_bignum2(b, key->p);
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buffer_put_bignum2(b, key->q);
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buffer_put_bignum2(b, key->g);
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buffer_put_bignum2(b, key->pub_key);
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buffer_put_bignum2(b, key->priv_key);
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buffer_put_string(b, comment, strlen(comment));
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}
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/*
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* Adds an identity to the authentication server. This call is not meant to
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* be used by normal applications.
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*/
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int
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ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
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{
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Buffer msg;
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int type;
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buffer_init(&msg);
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switch (key->type) {
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case KEY_RSA:
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ssh_encode_identity_rsa(&msg, key->rsa, comment);
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break;
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case KEY_DSA:
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ssh_encode_identity_dsa(&msg, key->dsa, comment);
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break;
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default:
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buffer_free(&msg);
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return 0;
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break;
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}
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if (ssh_request_reply(auth, &msg, &msg) == 0) {
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buffer_free(&msg);
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return 0;
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}
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type = buffer_get_char(&msg);
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buffer_free(&msg);
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return decode_reply(type);
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}
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/*
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* Removes an identity from the authentication server. This call is not
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* meant to be used by normal applications.
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*/
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int
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ssh_remove_identity(AuthenticationConnection *auth, Key *key)
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{
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Buffer msg;
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int type;
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unsigned char *blob;
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unsigned int blen;
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buffer_init(&msg);
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if (key->type == KEY_RSA) {
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buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
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buffer_put_int(&msg, BN_num_bits(key->rsa->n));
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buffer_put_bignum(&msg, key->rsa->e);
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buffer_put_bignum(&msg, key->rsa->n);
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} else if (key->type == KEY_DSA) {
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dsa_make_key_blob(key, &blob, &blen);
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buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
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buffer_put_string(&msg, blob, blen);
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xfree(blob);
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} else {
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buffer_free(&msg);
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return 0;
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}
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if (ssh_request_reply(auth, &msg, &msg) == 0) {
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buffer_free(&msg);
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return 0;
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}
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type = buffer_get_char(&msg);
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buffer_free(&msg);
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return decode_reply(type);
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}
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/*
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* Removes all identities from the agent. This call is not meant to be used
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* by normal applications.
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*/
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int
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ssh_remove_all_identities(AuthenticationConnection *auth, int version)
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{
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Buffer msg;
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int type;
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int code = (version==1) ?
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SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
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SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
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buffer_init(&msg);
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buffer_put_char(&msg, code);
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if (ssh_request_reply(auth, &msg, &msg) == 0) {
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buffer_free(&msg);
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return 0;
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}
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type = buffer_get_char(&msg);
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|
buffer_free(&msg);
|
|
return decode_reply(type);
|
|
}
|
|
|
|
int
|
|
decode_reply(int type)
|
|
{
|
|
switch (type) {
|
|
case SSH_AGENT_FAILURE:
|
|
log("SSH_AGENT_FAILURE");
|
|
return 0;
|
|
case SSH_AGENT_SUCCESS:
|
|
return 1;
|
|
default:
|
|
fatal("Bad response from authentication agent: %d", type);
|
|
}
|
|
/* NOTREACHED */
|
|
return 0;
|
|
}
|