path: root/source4/lib/tls/tls.c

/* 
   Unix SMB/CIFS implementation.

   transport layer security handling code

   Copyright (C) Andrew Tridgell 2005
   
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

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

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

#define DH_BITS 1024

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

/* hold per connection tls data */
struct tls_context {
	struct tls_params *params;
	struct socket_context *socket;
	struct fd_event *fde;
	gnutls_session session;
	BOOL done_handshake;
	BOOL have_first_byte;
	uint8_t first_byte;
	BOOL tls_enabled;
	BOOL tls_detect;
	const char *plain_chars;
	BOOL output_pending;
};


/*
  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, 0);
	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);
		EVENT_FD_NOT_WRITEABLE(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, 0);
	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(void *ptr)
{
	struct tls_context *tls = talloc_get_type(ptr, struct tls_context);
	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) {
		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;
}

/*
  see how many bytes are pending on the connection
*/
NTSTATUS tls_socket_pending(struct tls_context *tls, size_t *npending)
{
	if (!tls->tls_enabled || tls->tls_detect) {
		return socket_pending(tls->socket, npending);
	}
	*npending = gnutls_record_check_pending(tls->session);
	if (*npending == 0) {
		return socket_pending(tls->socket, npending);
	}
	return NT_STATUS_OK;
}

/*
  receive data either by tls or normal socket_recv
*/
NTSTATUS tls_socket_recv(struct tls_context *tls, void *buf, size_t wantlen, 
			 size_t *nread)
{
	int ret;
	NTSTATUS status;
	if (tls->tls_enabled && tls->tls_detect) {
		status = socket_recv(tls->socket, &tls->first_byte, 1, nread, 0);
		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, 0);
	}

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

	ret = gnutls_record_recv(tls->session, buf, wantlen);
	if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
		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
*/
NTSTATUS tls_socket_send(struct tls_context *tls, const DATA_BLOB *blob, size_t *sendlen)
{
	NTSTATUS status;
	int ret;

	if (!tls->tls_enabled) {
		return socket_send(tls->socket, blob, sendlen, 0);
	}

	status = tls_handshake(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) {
		return STATUS_MORE_ENTRIES;
	}
	if (ret < 0) {
		DEBUG(0,("gnutls_record_send of %d failed - %s\n", blob->length, gnutls_strerror(ret)));
		return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
	}
	*sendlen = ret;
	tls->output_pending = (ret < blob->length);
	return NT_STATUS_OK;
}


/*
  initialise global tls state
*/
struct tls_params *tls_initialise(TALLOC_CTX *mem_ctx)
{
	struct tls_params *params;
	int ret;
	const char *keyfile = lp_tls_keyfile();
	const char *certfile = lp_tls_certfile();
	const char *cafile = lp_tls_cafile();
	const char *crlfile = lp_tls_crlfile();
	void tls_cert_generate(TALLOC_CTX *, const char *, const char *, const char *);

	params = talloc(mem_ctx, struct tls_params);
	if (params == NULL) return NULL;

	if (!lp_tls_enabled() || keyfile == NULL || *keyfile == 0) {
		params->tls_enabled = False;
		return params;
	}

	if (!file_exist(cafile)) {
		tls_cert_generate(params, keyfile, certfile, cafile);
	}

	ret = gnutls_global_init();
	if (ret < 0) goto init_failed;

	gnutls_certificate_allocate_credentials(&params->x509_cred);
	if (ret < 0) goto init_failed;

	if (cafile && *cafile) {
		ret = gnutls_certificate_set_x509_trust_file(params->x509_cred, cafile, 
							     GNUTLS_X509_FMT_PEM);	
		if (ret < 0) {
			DEBUG(0,("TLS failed to initialise cafile %s\n", cafile));
			goto init_failed;
		}
	}

	if (crlfile && *crlfile) {
		ret = gnutls_certificate_set_x509_crl_file(params->x509_cred, 
							   crlfile, 
							   GNUTLS_X509_FMT_PEM);
		if (ret < 0) {
			DEBUG(0,("TLS failed to initialise crlfile %s\n", crlfile));
			goto init_failed;
		}
	}
	
	ret = gnutls_certificate_set_x509_key_file(params->x509_cred, 
						   certfile, keyfile,
						   GNUTLS_X509_FMT_PEM);
	if (ret < 0) {
		DEBUG(0,("TLS failed to initialise certfile %s and keyfile %s\n", 
			 certfile, keyfile));
		goto init_failed;
	}
	
	ret = gnutls_dh_params_init(&params->dh_params);
	if (ret < 0) goto init_failed;

	ret = gnutls_dh_params_generate2(params->dh_params, DH_BITS);
	if (ret < 0) goto init_failed;

	gnutls_certificate_set_dh_params(params->x509_cred, params->dh_params);

	params->tls_enabled = True;
	return params;

init_failed:
	DEBUG(0,("GNUTLS failed to initialise - %s\n", gnutls_strerror(ret)));
	params->tls_enabled = False;
	return params;
}


/*
  setup for a new connection
*/
struct tls_context *tls_init_server(struct tls_params *params, 
				    struct socket_context *socket,
				    struct fd_event *fde, 
				    const char *plain_chars,
				    BOOL tls_enable)
{
	struct tls_context *tls;
	int ret;

	tls = talloc(socket, struct tls_context);
	if (tls == NULL) return NULL;

	tls->socket          = socket;
	tls->fde             = fde;

	if (!params->tls_enabled || !tls_enable) {
		tls->tls_enabled = False;
		return tls;
	}

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

	TLSCHECK(gnutls_init(&tls->session, GNUTLS_SERVER));

	talloc_set_destructor(tls, tls_destructor);

	TLSCHECK(gnutls_set_default_priority(tls->session));
	TLSCHECK(gnutls_credentials_set(tls->session, GNUTLS_CRD_CERTIFICATE, 
					params->x509_cred));
	gnutls_certificate_server_set_request(tls->session, GNUTLS_CERT_REQUEST);
	gnutls_dh_set_prime_bits(tls->session, DH_BITS);
	gnutls_transport_set_ptr(tls->session, (gnutls_transport_ptr)tls);
	gnutls_transport_set_pull_function(tls->session, (gnutls_pull_func)tls_pull);
	gnutls_transport_set_push_function(tls->session, (gnutls_push_func)tls_push);
	gnutls_transport_set_lowat(tls->session, 0);

	tls->plain_chars = plain_chars;
	if (plain_chars) {
		tls->tls_detect = True;
	} else {
		tls->tls_detect = False;
	}

	tls->output_pending  = False;
	tls->params          = params;
	tls->done_handshake  = False;
	tls->have_first_byte = False;
	tls->tls_enabled     = True;
	
	return tls;

failed:
	DEBUG(0,("TLS init connection failed - %s\n", gnutls_strerror(ret)));
	tls->tls_enabled = False;
	params->tls_enabled = False;
	return tls;
}

BOOL tls_enabled(struct tls_context *tls)
{
	return tls->tls_enabled;
}

BOOL tls_support(struct tls_params *params)
{
	return params->tls_enabled;
}

#else

/* for systems without tls we just map the tls socket calls to the
   normal socket calls */

struct tls_params *tls_initialise(TALLOC_CTX *mem_ctx)
{
	return talloc_new(mem_ctx);
}

struct tls_context *tls_init_server(struct tls_params *params, 
				    struct socket_context *sock, 
				    struct fd_event *fde,
				    const char *plain_chars,
				    BOOL tls_enable)
{
	if (plain_chars == NULL) return NULL;
	return (struct tls_context *)sock;
}


NTSTATUS tls_socket_recv(struct tls_context *tls, void *buf, size_t wantlen, 
			 size_t *nread)
{
	return socket_recv((struct socket_context *)tls, buf, wantlen, nread, 0);
}

NTSTATUS tls_socket_send(struct tls_context *tls, const DATA_BLOB *blob, size_t *sendlen)
{
	return socket_send((struct socket_context *)tls, blob, sendlen, 0);
}

BOOL tls_enabled(struct tls_context *tls)
{
	return False;
}

BOOL tls_support(struct tls_params *params)
{
	return False;
}

NTSTATUS tls_socket_pending(struct tls_context *tls, size_t *npending)
{
	return socket_pending((struct socket_context *)tls, npending);
}

#endif