monitor.c

OpenSSL Source code for SFTP, SSH, and many others

	}
	s->used = 0;
}

int
mm_answer_pty(int socket, Buffer *m)
{
	extern struct monitor *pmonitor;
	Session *s;
	int res, fd0;

	debug3("%s entering", __func__);

	buffer_clear(m);
	s = session_new();
	if (s == NULL)
		goto error;
	s->authctxt = authctxt;
	s->pw = authctxt->pw;
	s->pid = pmonitor->m_pid;
	res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
	if (res == 0)
		goto error;
	fatal_add_cleanup(session_pty_cleanup2, (void *)s);
	pty_setowner(authctxt->pw, s->tty);

	buffer_put_int(m, 1);
	buffer_put_cstring(m, s->tty);
	mm_request_send(socket, MONITOR_ANS_PTY, m);

	mm_send_fd(socket, s->ptyfd);
	mm_send_fd(socket, s->ttyfd);

	/* We need to trick ttyslot */
	if (dup2(s->ttyfd, 0) == -1)
		fatal("%s: dup2", __func__);

	mm_record_login(s, authctxt->pw);

	/* Now we can close the file descriptor again */
	close(0);

	/* make sure nothing uses fd 0 */
	if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0)
		fatal("%s: open(/dev/null): %s", __func__, strerror(errno));
	if (fd0 != 0)
		error("%s: fd0 %d != 0", __func__, fd0);

	/* slave is not needed */
	close(s->ttyfd);
	s->ttyfd = s->ptyfd;
	/* no need to dup() because nobody closes ptyfd */
	s->ptymaster = s->ptyfd;

	debug3("%s: tty %s ptyfd %d",  __func__, s->tty, s->ttyfd);

	return (0);

 error:
	if (s != NULL)
		mm_session_close(s);
	buffer_put_int(m, 0);
	mm_request_send(socket, MONITOR_ANS_PTY, m);
	return (0);
}

int
mm_answer_pty_cleanup(int socket, Buffer *m)
{
	Session *s;
	char *tty;

	debug3("%s entering", __func__);

	tty = buffer_get_string(m, NULL);
	if ((s = session_by_tty(tty)) != NULL)
		mm_session_close(s);
	buffer_clear(m);
	xfree(tty);
	return (0);
}

int
mm_answer_sesskey(int socket, Buffer *m)
{
	BIGNUM *p;
	int rsafail;

	/* Turn off permissions */
	monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 1);

	if ((p = BN_new()) == NULL)
		fatal("%s: BN_new", __func__);

	buffer_get_bignum2(m, p);

	rsafail = ssh1_session_key(p);

	buffer_clear(m);
	buffer_put_int(m, rsafail);
	buffer_put_bignum2(m, p);

	BN_clear_free(p);

	mm_request_send(socket, MONITOR_ANS_SESSKEY, m);

	/* Turn on permissions for sessid passing */
	monitor_permit(mon_dispatch, MONITOR_REQ_SESSID, 1);

	return (0);
}

int
mm_answer_sessid(int socket, Buffer *m)
{
	int i;

	debug3("%s entering", __func__);

	if (buffer_len(m) != 16)
		fatal("%s: bad ssh1 session id", __func__);
	for (i = 0; i < 16; i++)
		session_id[i] = buffer_get_char(m);

	/* Turn on permissions for getpwnam */
	monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);

	return (0);
}

int
mm_answer_rsa_keyallowed(int socket, Buffer *m)
{
	BIGNUM *client_n;
	Key *key = NULL;
	u_char *blob = NULL;
	u_int blen = 0;
	int allowed = 0;

	debug3("%s entering", __func__);

	if (options.rsa_authentication && authctxt->valid) {
		if ((client_n = BN_new()) == NULL)
			fatal("%s: BN_new", __func__);
		buffer_get_bignum2(m, client_n);
		allowed = auth_rsa_key_allowed(authctxt->pw, client_n, &key);
		BN_clear_free(client_n);
	}
	buffer_clear(m);
	buffer_put_int(m, allowed);

	/* clear temporarily storage (used by generate challenge) */
	monitor_reset_key_state();

	if (allowed && key != NULL) {
		key->type = KEY_RSA;	/* cheat for key_to_blob */
		if (key_to_blob(key, &blob, &blen) == 0)
			fatal("%s: key_to_blob failed", __func__);
		buffer_put_string(m, blob, blen);

		/* Save temporarily for comparison in verify */
		key_blob = blob;
		key_bloblen = blen;
		key_blobtype = MM_RSAUSERKEY;
		key_free(key);
	}

	mm_append_debug(m);

	mm_request_send(socket, MONITOR_ANS_RSAKEYALLOWED, m);

	monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed);
	monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 0);
	return (0);
}

int
mm_answer_rsa_challenge(int socket, Buffer *m)
{
	Key *key = NULL;
	u_char *blob;
	u_int blen;

	debug3("%s entering", __func__);

	if (!authctxt->valid)
		fatal("%s: authctxt not valid", __func__);
	blob = buffer_get_string(m, &blen);
	if (!monitor_allowed_key(blob, blen))
		fatal("%s: bad key, not previously allowed", __func__);
	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
		fatal("%s: key type mismatch", __func__);
	if ((key = key_from_blob(blob, blen)) == NULL)
		fatal("%s: received bad key", __func__);

	if (ssh1_challenge)
		BN_clear_free(ssh1_challenge);
	ssh1_challenge = auth_rsa_generate_challenge(key);

	buffer_clear(m);
	buffer_put_bignum2(m, ssh1_challenge);

	debug3("%s sending reply", __func__);
	mm_request_send(socket, MONITOR_ANS_RSACHALLENGE, m);

	monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 1);
	return (0);
}

int
mm_answer_rsa_response(int socket, Buffer *m)
{
	Key *key = NULL;
	u_char *blob, *response;
	u_int blen, len;
	int success;

	debug3("%s entering", __func__);

	if (!authctxt->valid)
		fatal("%s: authctxt not valid", __func__);
	if (ssh1_challenge == NULL)
		fatal("%s: no ssh1_challenge", __func__);

	blob = buffer_get_string(m, &blen);
	if (!monitor_allowed_key(blob, blen))
		fatal("%s: bad key, not previously allowed", __func__);
	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
		fatal("%s: key type mismatch: %d", __func__, key_blobtype);
	if ((key = key_from_blob(blob, blen)) == NULL)
		fatal("%s: received bad key", __func__);
	response = buffer_get_string(m, &len);
	if (len != 16)
		fatal("%s: received bad response to challenge", __func__);
	success = auth_rsa_verify_response(key, ssh1_challenge, response);

	key_free(key);
	xfree(response);

	auth_method = key_blobtype == MM_RSAUSERKEY ? "rsa" : "rhosts-rsa";

	/* reset state */
	BN_clear_free(ssh1_challenge);
	ssh1_challenge = NULL;
	monitor_reset_key_state();

	buffer_clear(m);
	buffer_put_int(m, success);
	mm_request_send(socket, MONITOR_ANS_RSARESPONSE, m);

	return (success);
}

int
mm_answer_term(int socket, Buffer *req)
{
	extern struct monitor *pmonitor;
	int res, status;

	debug3("%s: tearing down sessions", __func__);

	/* The child is terminating */
	session_destroy_all(&mm_session_close);

	while (waitpid(pmonitor->m_pid, &status, 0) == -1)
		if (errno != EINTR)
			exit(1);

	res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;

	/* Terminate process */
	exit (res);
}

void
monitor_apply_keystate(struct monitor *pmonitor)
{
	if (compat20) {
		set_newkeys(MODE_IN);
		set_newkeys(MODE_OUT);
	} else {
		packet_set_protocol_flags(child_state.ssh1protoflags);
		packet_set_encryption_key(child_state.ssh1key,
		    child_state.ssh1keylen, child_state.ssh1cipher);
		xfree(child_state.ssh1key);
	}

	/* for rc4 and other stateful ciphers */
	packet_set_keycontext(MODE_OUT, child_state.keyout);
	xfree(child_state.keyout);
	packet_set_keycontext(MODE_IN, child_state.keyin);
	xfree(child_state.keyin);

	if (!compat20) {
		packet_set_iv(MODE_OUT, child_state.ivout);
		xfree(child_state.ivout);
		packet_set_iv(MODE_IN, child_state.ivin);
		xfree(child_state.ivin);
	}

	memcpy(&incoming_stream, &child_state.incoming,
	    sizeof(incoming_stream));
	memcpy(&outgoing_stream, &child_state.outgoing,
	    sizeof(outgoing_stream));

	/* Update with new address */
	if (options.compression)
		mm_init_compression(pmonitor->m_zlib);

	/* Network I/O buffers */
	/* XXX inefficient for large buffers, need: buffer_init_from_string */
	buffer_clear(&input);
	buffer_append(&input, child_state.input, child_state.ilen);
	memset(child_state.input, 0, child_state.ilen);
	xfree(child_state.input);

	buffer_clear(&output);
	buffer_append(&output, child_state.output, child_state.olen);
	memset(child_state.output, 0, child_state.olen);
	xfree(child_state.output);
}

static Kex *
mm_get_kex(Buffer *m)
{
	Kex *kex;
	void *blob;
	u_int bloblen;

	kex = xmalloc(sizeof(*kex));
	memset(kex, 0, sizeof(*kex));
	kex->session_id = buffer_get_string(m, &kex->session_id_len);
	if ((session_id2 == NULL) ||
	    (kex->session_id_len != session_id2_len) ||
	    (memcmp(kex->session_id, session_id2, session_id2_len) != 0))
		fatal("mm_get_get: internal error: bad session id");
	kex->we_need = buffer_get_int(m);
	kex->server = 1;
	kex->hostkey_type = buffer_get_int(m);
	kex->kex_type = buffer_get_int(m);
	blob = buffer_get_string(m, &bloblen);
	buffer_init(&kex->my);
	buffer_append(&kex->my, blob, bloblen);
	xfree(blob);
	blob = buffer_get_string(m, &bloblen);
	buffer_init(&kex->peer);
	buffer_append(&kex->peer, blob, bloblen);
	xfree(blob);
	kex->done = 1;
	kex->flags = buffer_get_int(m);
	kex->client_version_string = buffer_get_string(m, NULL);
	kex->server_version_string = buffer_get_string(m, NULL);
	kex->load_host_key=&get_hostkey_by_type;
	kex->host_key_index=&get_hostkey_index;

	return (kex);
}

/* This function requries careful sanity checking */

void
mm_get_keystate(struct monitor *pmonitor)
{
	Buffer m;
	u_char *blob, *p;
	u_int bloblen, plen;

	debug3("%s: Waiting for new keys", __func__);

	buffer_init(&m);
	mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, &m);
	if (!compat20) {
		child_state.ssh1protoflags = buffer_get_int(&m);
		child_state.ssh1cipher = buffer_get_int(&m);
		child_state.ssh1key = buffer_get_string(&m,
		    &child_state.ssh1keylen);
		child_state.ivout = buffer_get_string(&m,
		    &child_state.ivoutlen);
		child_state.ivin = buffer_get_string(&m, &child_state.ivinlen);
		goto skip;
	} else {
		/* Get the Kex for rekeying */
		*pmonitor->m_pkex = mm_get_kex(&m);
	}

	blob = buffer_get_string(&m, &bloblen);
	current_keys[MODE_OUT] = mm_newkeys_from_blob(blob, bloblen);
	xfree(blob);

	debug3("%s: Waiting for second key", __func__);
	blob = buffer_get_string(&m, &bloblen);
	current_keys[MODE_IN] = mm_newkeys_from_blob(blob, bloblen);
	xfree(blob);

	/* Now get sequence numbers for the packets */
	packet_set_seqnr(MODE_OUT, buffer_get_int(&m));
	packet_set_seqnr(MODE_IN, buffer_get_int(&m));

 skip:
	/* Get the key context */
	child_state.keyout = buffer_get_string(&m, &child_state.keyoutlen);
	child_state.keyin  = buffer_get_string(&m, &child_state.keyinlen);

	debug3("%s: Getting compression state", __func__);
	/* Get compression state */
	p = buffer_get_string(&m, &plen);
	if (plen != sizeof(child_state.outgoing))
		fatal("%s: bad request size", __func__);
	memcpy(&child_state.outgoing, p, sizeof(child_state.outgoing));
	xfree(p);

	p = buffer_get_string(&m, &plen);
	if (plen != sizeof(child_state.incoming))
		fatal("%s: bad request size", __func__);
	memcpy(&child_state.incoming, p, sizeof(child_state.incoming));
	xfree(p);

	/* Network I/O buffers */
	debug3("%s: Getting Network I/O buffers", __func__);
	child_state.input = buffer_get_string(&m, &child_state.ilen);
	child_state.output = buffer_get_string(&m, &child_state.olen);

	buffer_free(&m);
}


/* Allocation functions for zlib */
void *
mm_zalloc(struct mm_master *mm, u_int ncount, u_int size)
{
	void *address;

	address = mm_malloc(mm, size * ncount);

	return (address);
}

void
mm_zfree(struct mm_master *mm, void *address)
{
	mm_free(mm, address);
}

void
mm_init_compression(struct mm_master *mm)
{
	outgoing_stream.zalloc = (alloc_func)mm_zalloc;
	outgoing_stream.zfree = (free_func)mm_zfree;
	outgoing_stream.opaque = mm;

	incoming_stream.zalloc = (alloc_func)mm_zalloc;
	incoming_stream.zfree = (free_func)mm_zfree;
	incoming_stream.opaque = mm;
}

/* XXX */

#define FD_CLOSEONEXEC(x) do { \
	if (fcntl(x, F_SETFD, 1) == -1) \
		fatal("fcntl(%d, F_SETFD)", x); \
} while (0)

static void
monitor_socketpair(int *pair)
{
#ifdef HAVE_SOCKETPAIR
	if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
		fatal("%s: socketpair", __func__);
#else
	fatal("%s: UsePrivilegeSeparation=yes not supported",
	    __func__);
#endif
	FD_CLOSEONEXEC(pair[0]);
	FD_CLOSEONEXEC(pair[1]);
}

#define MM_MEMSIZE	65536

struct monitor *
monitor_init(void)
{
	struct monitor *mon;
	int pair[2];

	mon = xmalloc(sizeof(*mon));

	monitor_socketpair(pair);

	mon->m_recvfd = pair[0];
	mon->m_sendfd = pair[1];

	/* Used to share zlib space across processes */
	if (options.compression) {
		mon->m_zback = mm_create(NULL, MM_MEMSIZE);
		mon->m_zlib = mm_create(mon->m_zback, 20 * MM_MEMSIZE);

		/* Compression needs to share state across borders */
		mm_init_compression(mon->m_zlib);
	}

	return mon;
}

void
monitor_reinit(struct monitor *mon)
{
	int pair[2];

	monitor_socketpair(pair);

	mon->m_recvfd = pair[0];
	mon->m_sendfd = pair[1];
}