657 lines
15 KiB
C
657 lines
15 KiB
C
/* $OpenBSD: ssh-agent.c,v 1.26 2000/03/16 20:56:14 markus 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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* Created: Wed Mar 29 03:46:59 1995 ylo
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* The authentication agent program.
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*
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* $FreeBSD$
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*/
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#include "includes.h"
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RCSID("$OpenBSD: ssh-agent.c,v 1.26 2000/03/16 20:56:14 markus Exp $");
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#include "ssh.h"
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#include "rsa.h"
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#include "authfd.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 "packet.h"
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#include "getput.h"
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#include "mpaux.h"
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#include <openssl/md5.h>
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typedef struct {
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int fd;
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enum {
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AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
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} type;
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Buffer input;
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Buffer output;
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} SocketEntry;
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unsigned int sockets_alloc = 0;
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SocketEntry *sockets = NULL;
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typedef struct {
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RSA *key;
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char *comment;
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} Identity;
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unsigned int num_identities = 0;
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Identity *identities = NULL;
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int max_fd = 0;
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/* pid of shell == parent of agent */
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int parent_pid = -1;
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/* pathname and directory for AUTH_SOCKET */
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char socket_name[1024];
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char socket_dir[1024];
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extern char *__progname;
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void
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process_request_identity(SocketEntry *e)
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{
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Buffer msg;
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int i;
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buffer_init(&msg);
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buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER);
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buffer_put_int(&msg, num_identities);
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for (i = 0; i < num_identities; i++) {
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buffer_put_int(&msg, BN_num_bits(identities[i].key->n));
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buffer_put_bignum(&msg, identities[i].key->e);
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buffer_put_bignum(&msg, identities[i].key->n);
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buffer_put_string(&msg, identities[i].comment,
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strlen(identities[i].comment));
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}
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buffer_put_int(&e->output, buffer_len(&msg));
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buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
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buffer_free(&msg);
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}
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void
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process_authentication_challenge(SocketEntry *e)
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{
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int i, pub_bits, len;
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BIGNUM *pub_e, *pub_n, *challenge;
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Buffer msg;
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MD5_CTX md;
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unsigned char buf[32], mdbuf[16], session_id[16];
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unsigned int response_type;
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buffer_init(&msg);
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pub_e = BN_new();
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pub_n = BN_new();
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challenge = BN_new();
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pub_bits = buffer_get_int(&e->input);
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buffer_get_bignum(&e->input, pub_e);
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buffer_get_bignum(&e->input, pub_n);
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buffer_get_bignum(&e->input, challenge);
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if (buffer_len(&e->input) == 0) {
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/* Compatibility code for old servers. */
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memset(session_id, 0, 16);
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response_type = 0;
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} else {
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/* New code. */
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buffer_get(&e->input, (char *) session_id, 16);
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response_type = buffer_get_int(&e->input);
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}
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for (i = 0; i < num_identities; i++)
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if (pub_bits == BN_num_bits(identities[i].key->n) &&
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BN_cmp(pub_e, identities[i].key->e) == 0 &&
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BN_cmp(pub_n, identities[i].key->n) == 0) {
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/* Decrypt the challenge using the private key. */
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rsa_private_decrypt(challenge, challenge, identities[i].key);
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/* Compute the desired response. */
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switch (response_type) {
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case 0:/* As of protocol 1.0 */
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/* This response type is no longer supported. */
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log("Compatibility with ssh protocol 1.0 no longer supported.");
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buffer_put_char(&msg, SSH_AGENT_FAILURE);
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goto send;
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case 1:/* As of protocol 1.1 */
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/* The response is MD5 of decrypted challenge plus session id. */
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len = BN_num_bytes(challenge);
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if (len <= 0 || len > 32) {
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fatal("process_authentication_challenge: "
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"bad challenge length %d", len);
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}
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memset(buf, 0, 32);
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BN_bn2bin(challenge, buf + 32 - len);
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MD5_Init(&md);
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MD5_Update(&md, buf, 32);
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MD5_Update(&md, session_id, 16);
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MD5_Final(mdbuf, &md);
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break;
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default:
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fatal("process_authentication_challenge: bad response_type %d",
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response_type);
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break;
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}
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/* Send the response. */
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buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
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for (i = 0; i < 16; i++)
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buffer_put_char(&msg, mdbuf[i]);
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goto send;
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}
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/* Unknown identity. Send failure. */
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buffer_put_char(&msg, SSH_AGENT_FAILURE);
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send:
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buffer_put_int(&e->output, buffer_len(&msg));
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buffer_append(&e->output, buffer_ptr(&msg),
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buffer_len(&msg));
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buffer_free(&msg);
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BN_clear_free(pub_e);
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BN_clear_free(pub_n);
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BN_clear_free(challenge);
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}
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void
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process_remove_identity(SocketEntry *e)
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{
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unsigned int bits;
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unsigned int i;
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BIGNUM *dummy, *n;
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dummy = BN_new();
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n = BN_new();
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/* Get the key from the packet. */
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bits = buffer_get_int(&e->input);
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buffer_get_bignum(&e->input, dummy);
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buffer_get_bignum(&e->input, n);
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if (bits != BN_num_bits(n))
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error("Warning: identity keysize mismatch: actual %d, announced %d",
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BN_num_bits(n), bits);
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/* Check if we have the key. */
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for (i = 0; i < num_identities; i++)
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if (BN_cmp(identities[i].key->n, n) == 0) {
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/*
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* We have this key. Free the old key. Since we
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* don\'t want to leave empty slots in the middle of
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* the array, we actually free the key there and copy
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* data from the last entry.
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*/
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RSA_free(identities[i].key);
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xfree(identities[i].comment);
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if (i < num_identities - 1)
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identities[i] = identities[num_identities - 1];
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num_identities--;
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BN_clear_free(dummy);
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BN_clear_free(n);
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/* Send success. */
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buffer_put_int(&e->output, 1);
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buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
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return;
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}
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/* We did not have the key. */
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BN_clear(dummy);
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BN_clear(n);
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/* Send failure. */
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buffer_put_int(&e->output, 1);
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buffer_put_char(&e->output, SSH_AGENT_FAILURE);
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}
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/*
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* Removes all identities from the agent.
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*/
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void
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process_remove_all_identities(SocketEntry *e)
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{
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unsigned int i;
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/* Loop over all identities and clear the keys. */
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for (i = 0; i < num_identities; i++) {
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RSA_free(identities[i].key);
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xfree(identities[i].comment);
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}
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/* Mark that there are no identities. */
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num_identities = 0;
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/* Send success. */
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buffer_put_int(&e->output, 1);
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buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
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return;
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}
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/*
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* Adds an identity to the agent.
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*/
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void
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process_add_identity(SocketEntry *e)
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{
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RSA *k;
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int i;
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BIGNUM *aux;
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BN_CTX *ctx;
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if (num_identities == 0)
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identities = xmalloc(sizeof(Identity));
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else
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identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity));
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identities[num_identities].key = RSA_new();
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k = identities[num_identities].key;
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buffer_get_int(&e->input); /* bits */
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k->n = BN_new();
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buffer_get_bignum(&e->input, k->n);
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k->e = BN_new();
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buffer_get_bignum(&e->input, k->e);
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k->d = BN_new();
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buffer_get_bignum(&e->input, k->d);
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k->iqmp = BN_new();
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buffer_get_bignum(&e->input, k->iqmp);
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/* SSH and SSL have p and q swapped */
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k->q = BN_new();
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buffer_get_bignum(&e->input, k->q); /* p */
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k->p = BN_new();
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buffer_get_bignum(&e->input, k->p); /* q */
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/* Generate additional parameters */
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aux = BN_new();
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ctx = BN_CTX_new();
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BN_sub(aux, k->q, BN_value_one());
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k->dmq1 = BN_new();
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BN_mod(k->dmq1, k->d, aux, ctx);
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BN_sub(aux, k->p, BN_value_one());
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k->dmp1 = BN_new();
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BN_mod(k->dmp1, k->d, aux, ctx);
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BN_clear_free(aux);
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BN_CTX_free(ctx);
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identities[num_identities].comment = buffer_get_string(&e->input, NULL);
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/* Check if we already have the key. */
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for (i = 0; i < num_identities; i++)
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if (BN_cmp(identities[i].key->n, k->n) == 0) {
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/*
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* We already have this key. Clear and free the new
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* data and return success.
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*/
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RSA_free(k);
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xfree(identities[num_identities].comment);
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/* Send success. */
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buffer_put_int(&e->output, 1);
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buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
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return;
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}
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/* Increment the number of identities. */
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num_identities++;
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/* Send a success message. */
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buffer_put_int(&e->output, 1);
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buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
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}
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void
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process_message(SocketEntry *e)
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{
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unsigned int msg_len;
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unsigned int type;
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unsigned char *cp;
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if (buffer_len(&e->input) < 5)
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return; /* Incomplete message. */
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cp = (unsigned char *) buffer_ptr(&e->input);
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msg_len = GET_32BIT(cp);
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if (msg_len > 256 * 1024) {
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shutdown(e->fd, SHUT_RDWR);
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close(e->fd);
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e->type = AUTH_UNUSED;
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return;
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}
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if (buffer_len(&e->input) < msg_len + 4)
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return;
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buffer_consume(&e->input, 4);
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type = buffer_get_char(&e->input);
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switch (type) {
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case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
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process_request_identity(e);
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break;
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case SSH_AGENTC_RSA_CHALLENGE:
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process_authentication_challenge(e);
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break;
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case SSH_AGENTC_ADD_RSA_IDENTITY:
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process_add_identity(e);
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break;
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case SSH_AGENTC_REMOVE_RSA_IDENTITY:
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process_remove_identity(e);
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break;
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case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
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process_remove_all_identities(e);
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break;
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default:
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/* Unknown message. Respond with failure. */
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error("Unknown message %d", type);
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buffer_clear(&e->input);
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buffer_put_int(&e->output, 1);
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buffer_put_char(&e->output, SSH_AGENT_FAILURE);
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break;
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}
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}
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void
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new_socket(int type, int fd)
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{
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unsigned int i, old_alloc;
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if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
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error("fcntl O_NONBLOCK: %s", strerror(errno));
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if (fd > max_fd)
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max_fd = fd;
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for (i = 0; i < sockets_alloc; i++)
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if (sockets[i].type == AUTH_UNUSED) {
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sockets[i].fd = fd;
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sockets[i].type = type;
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buffer_init(&sockets[i].input);
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buffer_init(&sockets[i].output);
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return;
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}
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old_alloc = sockets_alloc;
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sockets_alloc += 10;
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if (sockets)
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sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
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else
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sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
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for (i = old_alloc; i < sockets_alloc; i++)
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sockets[i].type = AUTH_UNUSED;
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sockets[old_alloc].type = type;
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sockets[old_alloc].fd = fd;
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buffer_init(&sockets[old_alloc].input);
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buffer_init(&sockets[old_alloc].output);
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}
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void
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prepare_select(fd_set *readset, fd_set *writeset)
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{
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unsigned int i;
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for (i = 0; i < sockets_alloc; i++)
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switch (sockets[i].type) {
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case AUTH_SOCKET:
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case AUTH_CONNECTION:
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FD_SET(sockets[i].fd, readset);
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if (buffer_len(&sockets[i].output) > 0)
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FD_SET(sockets[i].fd, writeset);
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break;
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case AUTH_UNUSED:
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break;
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default:
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fatal("Unknown socket type %d", sockets[i].type);
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break;
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}
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}
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void
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after_select(fd_set *readset, fd_set *writeset)
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{
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unsigned int i;
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int len, sock;
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socklen_t slen;
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char buf[1024];
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struct sockaddr_un sunaddr;
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for (i = 0; i < sockets_alloc; i++)
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switch (sockets[i].type) {
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case AUTH_UNUSED:
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break;
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case AUTH_SOCKET:
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if (FD_ISSET(sockets[i].fd, readset)) {
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slen = sizeof(sunaddr);
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sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &slen);
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if (sock < 0) {
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perror("accept from AUTH_SOCKET");
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break;
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}
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new_socket(AUTH_CONNECTION, sock);
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}
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break;
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case AUTH_CONNECTION:
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if (buffer_len(&sockets[i].output) > 0 &&
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FD_ISSET(sockets[i].fd, writeset)) {
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len = write(sockets[i].fd, buffer_ptr(&sockets[i].output),
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buffer_len(&sockets[i].output));
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if (len <= 0) {
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shutdown(sockets[i].fd, SHUT_RDWR);
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close(sockets[i].fd);
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sockets[i].type = AUTH_UNUSED;
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break;
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}
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buffer_consume(&sockets[i].output, len);
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}
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if (FD_ISSET(sockets[i].fd, readset)) {
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len = read(sockets[i].fd, buf, sizeof(buf));
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if (len <= 0) {
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shutdown(sockets[i].fd, SHUT_RDWR);
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close(sockets[i].fd);
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sockets[i].type = AUTH_UNUSED;
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break;
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}
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buffer_append(&sockets[i].input, buf, len);
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process_message(&sockets[i]);
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}
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break;
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default:
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fatal("Unknown type %d", sockets[i].type);
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}
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}
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void
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check_parent_exists(int sig)
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{
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if (kill(parent_pid, 0) < 0) {
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/* printf("Parent has died - Authentication agent exiting.\n"); */
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exit(1);
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}
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signal(SIGALRM, check_parent_exists);
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alarm(10);
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}
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void
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cleanup_socket(void)
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{
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remove(socket_name);
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rmdir(socket_dir);
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}
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void
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cleanup_exit(int i)
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{
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cleanup_socket();
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exit(i);
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}
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void
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usage()
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{
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fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
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fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
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__progname);
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exit(1);
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}
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int
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main(int ac, char **av)
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{
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fd_set readset, writeset;
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int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
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struct sockaddr_un sunaddr;
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pid_t pid;
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char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
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/* check if RSA support exists */
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if (rsa_alive() == 0) {
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fprintf(stderr,
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"%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
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__progname);
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exit(1);
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}
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while ((ch = getopt(ac, av, "cks")) != -1) {
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switch (ch) {
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case 'c':
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if (s_flag)
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usage();
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c_flag++;
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break;
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case 'k':
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k_flag++;
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break;
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case 's':
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if (c_flag)
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usage();
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s_flag++;
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break;
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default:
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usage();
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}
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}
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ac -= optind;
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av += optind;
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|
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if (ac > 0 && (c_flag || k_flag || s_flag))
|
|
usage();
|
|
|
|
if (ac == 0 && !c_flag && !k_flag && !s_flag) {
|
|
shell = getenv("SHELL");
|
|
if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
|
|
c_flag = 1;
|
|
}
|
|
if (k_flag) {
|
|
pidstr = getenv(SSH_AGENTPID_ENV_NAME);
|
|
if (pidstr == NULL) {
|
|
fprintf(stderr, "%s not set, cannot kill agent\n",
|
|
SSH_AGENTPID_ENV_NAME);
|
|
exit(1);
|
|
}
|
|
pid = atoi(pidstr);
|
|
if (pid < 1) { /* XXX PID_MAX check too */
|
|
fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
|
|
SSH_AGENTPID_ENV_NAME, pidstr);
|
|
exit(1);
|
|
}
|
|
if (kill(pid, SIGTERM) == -1) {
|
|
perror("kill");
|
|
exit(1);
|
|
}
|
|
format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
|
|
printf(format, SSH_AUTHSOCKET_ENV_NAME);
|
|
printf(format, SSH_AGENTPID_ENV_NAME);
|
|
printf("echo Agent pid %d killed;\n", pid);
|
|
exit(0);
|
|
}
|
|
parent_pid = getpid();
|
|
|
|
/* Create private directory for agent socket */
|
|
strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
|
|
if (mkdtemp(socket_dir) == NULL) {
|
|
perror("mkdtemp: private socket dir");
|
|
exit(1);
|
|
}
|
|
snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
|
|
parent_pid);
|
|
|
|
/*
|
|
* Create socket early so it will exist before command gets run from
|
|
* the parent.
|
|
*/
|
|
sock = socket(AF_UNIX, SOCK_STREAM, 0);
|
|
if (sock < 0) {
|
|
perror("socket");
|
|
cleanup_exit(1);
|
|
}
|
|
memset(&sunaddr, 0, sizeof(sunaddr));
|
|
sunaddr.sun_family = AF_UNIX;
|
|
strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
|
|
if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
|
|
perror("bind");
|
|
cleanup_exit(1);
|
|
}
|
|
if (listen(sock, 5) < 0) {
|
|
perror("listen");
|
|
cleanup_exit(1);
|
|
}
|
|
/*
|
|
* Fork, and have the parent execute the command, if any, or present
|
|
* the socket data. The child continues as the authentication agent.
|
|
*/
|
|
pid = fork();
|
|
if (pid == -1) {
|
|
perror("fork");
|
|
exit(1);
|
|
}
|
|
if (pid != 0) { /* Parent - execute the given command. */
|
|
close(sock);
|
|
snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
|
|
if (ac == 0) {
|
|
format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
|
|
printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
|
|
SSH_AUTHSOCKET_ENV_NAME);
|
|
printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
|
|
SSH_AGENTPID_ENV_NAME);
|
|
printf("echo Agent pid %d;\n", pid);
|
|
exit(0);
|
|
}
|
|
setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1);
|
|
setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1);
|
|
execvp(av[0], av);
|
|
perror(av[0]);
|
|
exit(1);
|
|
}
|
|
close(0);
|
|
close(1);
|
|
close(2);
|
|
|
|
if (setsid() == -1) {
|
|
perror("setsid");
|
|
cleanup_exit(1);
|
|
}
|
|
if (atexit(cleanup_socket) < 0) {
|
|
perror("atexit");
|
|
cleanup_exit(1);
|
|
}
|
|
new_socket(AUTH_SOCKET, sock);
|
|
if (ac > 0) {
|
|
signal(SIGALRM, check_parent_exists);
|
|
alarm(10);
|
|
}
|
|
signal(SIGINT, SIG_IGN);
|
|
signal(SIGPIPE, SIG_IGN);
|
|
signal(SIGHUP, cleanup_exit);
|
|
signal(SIGTERM, cleanup_exit);
|
|
while (1) {
|
|
FD_ZERO(&readset);
|
|
FD_ZERO(&writeset);
|
|
prepare_select(&readset, &writeset);
|
|
if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) {
|
|
if (errno == EINTR)
|
|
continue;
|
|
exit(1);
|
|
}
|
|
after_select(&readset, &writeset);
|
|
}
|
|
/* NOTREACHED */
|
|
}
|