tls.c

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/* 
   Unix SMB/CIFS implementation.

   transport layer security handling code

   Copyright (C) Andrew Tridgell 2004-2005
   Copyright (C) Stefan Metzmacher 2004
   Copyright (C) Andrew Bartlett 2006
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "lib/events/events.h"
#include "lib/socket/socket.h"
#include "lib/tls/tls.h"
#include "param/param.h"

#if ENABLE_GNUTLS
#include "gnutls/gnutls.h"

#define DH_BITS 1024

#if defined(HAVE_GNUTLS_DATUM) && !defined(HAVE_GNUTLS_DATUM_T)
typedef gnutls_datum gnutls_datum_t;
#endif

/* hold persistent tls data */
struct tls_params {
	gnutls_certificate_credentials x509_cred;
	gnutls_dh_params dh_params;
	bool tls_enabled;
};
#endif

/* hold per connection tls data */
struct tls_context {
	struct socket_context *socket;
	struct fd_event *fde;
	bool tls_enabled;
#if ENABLE_GNUTLS
	gnutls_session session;
	bool done_handshake;
	bool have_first_byte;
	uint8_t first_byte;
	bool tls_detect;
	const char *plain_chars;
	bool output_pending;
	gnutls_certificate_credentials xcred;
	bool interrupted;
#endif
};

bool tls_enabled(struct socket_context *sock)
{
	struct tls_context *tls;
	if (!sock) {
		return false;
	}
	if (strcmp(sock->backend_name, "tls") != 0) {
		return false;
	}
	tls = talloc_get_type(sock->private_data, struct tls_context);
	if (!tls) {
		return false;
	}
	return tls->tls_enabled;
}


#if ENABLE_GNUTLS

static const struct socket_ops tls_socket_ops;

static NTSTATUS tls_socket_init(struct socket_context *sock)
{
	switch (sock->type) {
	case SOCKET_TYPE_STREAM:
		break;
	default:
		return NT_STATUS_INVALID_PARAMETER;
	}

	sock->backend_name = "tls";

	return NT_STATUS_OK;
}

#define TLSCHECK(call) do { \
	ret = call; \
	if (ret < 0) { \
		DEBUG(0,("TLS %s - %s\n", #call, gnutls_strerror(ret))); \
		goto failed; \
	} \
} while (0)


/*
  callback for reading from a socket
*/
static ssize_t tls_pull(gnutls_transport_ptr ptr, void *buf, size_t size)
{
	struct tls_context *tls = talloc_get_type(ptr, struct tls_context);
	NTSTATUS status;
	size_t nread;
	
	if (tls->have_first_byte) {
		*(uint8_t *)buf = tls->first_byte;
		tls->have_first_byte = false;
		return 1;
	}

	status = socket_recv(tls->socket, buf, size, &nread);
	if (NT_STATUS_EQUAL(status, NT_STATUS_END_OF_FILE)) {
		return 0;
	}
	if (NT_STATUS_IS_ERR(status)) {
		EVENT_FD_NOT_READABLE(tls->fde);
		EVENT_FD_NOT_WRITEABLE(tls->fde);
		errno = EBADF;
		return -1;
	}
	if (!NT_STATUS_IS_OK(status)) {
		EVENT_FD_READABLE(tls->fde);
		errno = EAGAIN;
		return -1;
	}
	if (tls->output_pending) {
		EVENT_FD_WRITEABLE(tls->fde);
	}
	if (size != nread) {
		EVENT_FD_READABLE(tls->fde);
	}
	return nread;
}

/*
  callback for writing to a socket
*/
static ssize_t tls_push(gnutls_transport_ptr ptr, const void *buf, size_t size)
{
	struct tls_context *tls = talloc_get_type(ptr, struct tls_context);
	NTSTATUS status;
	size_t nwritten;
	DATA_BLOB b;

	if (!tls->tls_enabled) {
		return size;
	}

	b.data = discard_const(buf);
	b.length = size;

	status = socket_send(tls->socket, &b, &nwritten);
	if (NT_STATUS_EQUAL(status, STATUS_MORE_ENTRIES)) {
		errno = EAGAIN;
		return -1;
	}
	if (!NT_STATUS_IS_OK(status)) {
		EVENT_FD_WRITEABLE(tls->fde);
		return -1;
	}
	if (size != nwritten) {
		EVENT_FD_WRITEABLE(tls->fde);
	}
	return nwritten;
}

/*
  destroy a tls session
 */
static int tls_destructor(struct tls_context *tls)
{
	int ret;
	ret = gnutls_bye(tls->session, GNUTLS_SHUT_WR);
	if (ret < 0) {
		DEBUG(0,("TLS gnutls_bye failed - %s\n", gnutls_strerror(ret)));
	}
	return 0;
}


/*
  possibly continue the handshake process
*/
static NTSTATUS tls_handshake(struct tls_context *tls)
{
	int ret;

	if (tls->done_handshake) {
		return NT_STATUS_OK;
	}
	
	ret = gnutls_handshake(tls->session);
	if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
		if (gnutls_record_get_direction(tls->session) == 1) {
			EVENT_FD_WRITEABLE(tls->fde);
		}
		return STATUS_MORE_ENTRIES;
	}
	if (ret < 0) {
		DEBUG(0,("TLS gnutls_handshake failed - %s\n", gnutls_strerror(ret)));
		return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
	}
	tls->done_handshake = true;
	return NT_STATUS_OK;
}

/*
  possibly continue an interrupted operation
*/
static NTSTATUS tls_interrupted(struct tls_context *tls)
{
	int ret;

	if (!tls->interrupted) {
		return NT_STATUS_OK;
	}
	if (gnutls_record_get_direction(tls->session) == 1) {
		ret = gnutls_record_send(tls->session, NULL, 0);
	} else {
		ret = gnutls_record_recv(tls->session, NULL, 0);
	}
	if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
		return STATUS_MORE_ENTRIES;
	}
	tls->interrupted = false;
	return NT_STATUS_OK;
}

/*
  see how many bytes are pending on the connection
*/
static NTSTATUS tls_socket_pending(struct socket_context *sock, size_t *npending)
{
	struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
	if (!tls->tls_enabled || tls->tls_detect) {
		return socket_pending(tls->socket, npending);
	}
	*npending = gnutls_record_check_pending(tls->session);
	if (*npending == 0) {
		NTSTATUS status = socket_pending(tls->socket, npending);
		if (*npending == 0) {
			/* seems to be a gnutls bug */
			(*npending) = 100;
		}
		return status;
	}
	return NT_STATUS_OK;
}

/*
  receive data either by tls or normal socket_recv
*/
static NTSTATUS tls_socket_recv(struct socket_context *sock, void *buf, 
				size_t wantlen, size_t *nread)
{
	int ret;
	NTSTATUS status;
	struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);

	if (tls->tls_enabled && tls->tls_detect) {
		status = socket_recv(tls->socket, &tls->first_byte, 1, nread);
		NT_STATUS_NOT_OK_RETURN(status);
		if (*nread == 0) return NT_STATUS_OK;
		tls->tls_detect = false;
		/* look for the first byte of a valid HTTP operation */
		if (strchr(tls->plain_chars, tls->first_byte)) {
			/* not a tls link */
			tls->tls_enabled = false;
			*(uint8_t *)buf = tls->first_byte;
			return NT_STATUS_OK;
		}
		tls->have_first_byte = true;
	}

	if (!tls->tls_enabled) {
		return socket_recv(tls->socket, buf, wantlen, nread);
	}

	status = tls_handshake(tls);
	NT_STATUS_NOT_OK_RETURN(status);

	status = tls_interrupted(tls);
	NT_STATUS_NOT_OK_RETURN(status);

	ret = gnutls_record_recv(tls->session, buf, wantlen);
	if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
		if (gnutls_record_get_direction(tls->session) == 1) {
			EVENT_FD_WRITEABLE(tls->fde);
		}
		tls->interrupted = true;
		return STATUS_MORE_ENTRIES;
	}
	if (ret < 0) {
		return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
	}
	*nread = ret;
	return NT_STATUS_OK;
}


/*
  send data either by tls or normal socket_recv
*/
static NTSTATUS tls_socket_send(struct socket_context *sock, 
				const DATA_BLOB *blob, size_t *sendlen)
{
	NTSTATUS status;
	int ret;
	struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);

	if (!tls->tls_enabled) {
		return socket_send(tls->socket, blob, sendlen);
	}

	status = tls_handshake(tls);
	NT_STATUS_NOT_OK_RETURN(status);

	status = tls_interrupted(tls);
	NT_STATUS_NOT_OK_RETURN(status);

	ret = gnutls_record_send(tls->session, blob->data, blob->length);
	if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
		if (gnutls_record_get_direction(tls->session) == 1) {
			EVENT_FD_WRITEABLE(tls->fde);
		}
		tls->interrupted = true;
		return STATUS_MORE_ENTRIES;
	}
	if (ret < 0) {
		DEBUG(0,("gnutls_record_send of %d failed - %s\n", (int)blob->length, gnutls_strerror(ret)));
		return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
	}
	*sendlen = ret;