source: vendor/3.5.5/source4/lib/tls/tls.c

/* 
   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 tevent_fd *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(4,("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;
        tls->output_pending = (ret < blob->length);
        return NT_STATUS_OK;
}


/*
  initialise global tls state
*/
struct tls_params *tls_initialise(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx)
{
        struct tls_params *params;
        int ret;
        TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
        const char *keyfile = lp_tls_keyfile(tmp_ctx, lp_ctx);
        const char *certfile = lp_tls_certfile(tmp_ctx, lp_ctx);
        const char *cafile = lp_tls_cafile(tmp_ctx, lp_ctx);
        const char *crlfile = lp_tls_crlfile(tmp_ctx, lp_ctx);
        const char *dhpfile = lp_tls_dhpfile(tmp_ctx, lp_ctx);
        void tls_cert_generate(TALLOC_CTX *, const char *, const char *, const char *, const char *);
        params = talloc(mem_ctx, struct tls_params);
        if (params == NULL) {
                talloc_free(tmp_ctx);
                return NULL;
        }

        if (!lp_tls_enabled(lp_ctx) || keyfile == NULL || *keyfile == 0) {
                params->tls_enabled = false;
                talloc_free(tmp_ctx);
                return params;
        }

        if (!file_exist(cafile)) {
                char *hostname = talloc_asprintf(mem_ctx, "%s.%s",
                                                 lp_netbios_name(lp_ctx), lp_realm(lp_ctx));
                if (hostname == NULL) {
                        goto init_failed;
                }
                tls_cert_generate(params, hostname, keyfile, certfile, cafile);
                talloc_free(hostname);
        }

        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;

        if (dhpfile && *dhpfile) {
                gnutls_datum_t dhparms;
                size_t size;
                dhparms.data = (uint8_t *)file_load(dhpfile, &size, 0, mem_ctx);

                if (!dhparms.data) {
                        DEBUG(0,("Failed to read DH Parms from %s\n", dhpfile));
                        goto init_failed;
                }
                dhparms.size = size;
                        
                ret = gnutls_dh_params_import_pkcs3(params->dh_params, &dhparms, GNUTLS_X509_FMT_PEM);
                if (ret < 0) goto init_failed;
        } else {
                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;

        talloc_free(tmp_ctx);
        return params;

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


/*
  setup for a new connection
*/
struct socket_context *tls_init_server(struct tls_params *params, 
                                       struct socket_context *socket_ctx,
                                       struct tevent_fd *fde, 
                                       const char *plain_chars)
{
        struct tls_context *tls;
        int ret;
        struct socket_context *new_sock;
        NTSTATUS nt_status;
        
        nt_status = socket_create_with_ops(socket_ctx, &tls_socket_ops, &new_sock, 
                                           SOCKET_TYPE_STREAM, 
                                           socket_ctx->flags | SOCKET_FLAG_ENCRYPT);
        if (!NT_STATUS_IS_OK(nt_status)) {
                return NULL;
        }

        tls = talloc(new_sock, struct tls_context);
        if (tls == NULL) {
                return NULL;
        }

        tls->socket          = socket_ctx;
        talloc_steal(tls, socket_ctx);
        tls->fde             = fde;

        new_sock->private_data    = tls;

        if (!params->tls_enabled) {
                talloc_free(new_sock);
                return NULL;
        }

        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->done_handshake  = false;
        tls->have_first_byte = false;
        tls->tls_enabled     = true;
        tls->interrupted     = false;
        
        new_sock->state = SOCKET_STATE_SERVER_CONNECTED;

        return new_sock;

failed:
        DEBUG(0,("TLS init connection failed - %s\n", gnutls_strerror(ret)));
        talloc_free(new_sock);
        return NULL;
}


/*
  setup for a new client connection
*/
struct socket_context *tls_init_client(struct socket_context *socket_ctx,
                                       struct tevent_fd *fde,
                                       const char *ca_path)
{
        struct tls_context *tls;
        int ret = 0;
        const int cert_type_priority[] = { GNUTLS_CRT_X509, GNUTLS_CRT_OPENPGP, 0 };
        struct socket_context *new_sock;
        NTSTATUS nt_status;
        
        nt_status = socket_create_with_ops(socket_ctx, &tls_socket_ops, &new_sock, 
                                           SOCKET_TYPE_STREAM, 
                                           socket_ctx->flags | SOCKET_FLAG_ENCRYPT);
        if (!NT_STATUS_IS_OK(nt_status)) {
                return NULL;
        }

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

        tls->socket          = socket_ctx;
        talloc_steal(tls, socket_ctx);
        tls->fde             = fde;

        new_sock->private_data    = tls;

        gnutls_global_init();

        gnutls_certificate_allocate_credentials(&tls->xcred);
        gnutls_certificate_set_x509_trust_file(tls->xcred, ca_path, GNUTLS_X509_FMT_PEM);
        TLSCHECK(gnutls_init(&tls->session, GNUTLS_CLIENT));
        TLSCHECK(gnutls_set_default_priority(tls->session));
        gnutls_certificate_type_set_priority(tls->session, cert_type_priority);
        TLSCHECK(gnutls_credentials_set(tls->session, GNUTLS_CRD_CERTIFICATE, tls->xcred));

        talloc_set_destructor(tls, tls_destructor);

        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->tls_detect = false;

        tls->output_pending  = false;
        tls->done_handshake  = false;
        tls->have_first_byte = false;
        tls->tls_enabled     = true;
        tls->interrupted     = false;
        
        new_sock->state = SOCKET_STATE_CLIENT_CONNECTED;

        return new_sock;

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

static NTSTATUS tls_socket_set_option(struct socket_context *sock, const char *option, const char *val)
{
        set_socket_options(socket_get_fd(sock), option);
        return NT_STATUS_OK;
}

static char *tls_socket_get_peer_name(struct socket_context *sock, TALLOC_CTX *mem_ctx)
{
        struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
        return socket_get_peer_name(tls->socket, mem_ctx);
}

static struct socket_address *tls_socket_get_peer_addr(struct socket_context *sock, TALLOC_CTX *mem_ctx)
{
        struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
        return socket_get_peer_addr(tls->socket, mem_ctx);
}

static struct socket_address *tls_socket_get_my_addr(struct socket_context *sock, TALLOC_CTX *mem_ctx)
{
        struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
        return socket_get_my_addr(tls->socket, mem_ctx);
}

static int tls_socket_get_fd(struct socket_context *sock)
{
        struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
        return socket_get_fd(tls->socket);
}

static const struct socket_ops tls_socket_ops = {
        .name                   = "tls",
        .fn_init                = tls_socket_init,
        .fn_recv                = tls_socket_recv,
        .fn_send                = tls_socket_send,
        .fn_pending             = tls_socket_pending,

        .fn_set_option          = tls_socket_set_option,

        .fn_get_peer_name       = tls_socket_get_peer_name,
        .fn_get_peer_addr       = tls_socket_get_peer_addr,
        .fn_get_my_addr         = tls_socket_get_my_addr,
        .fn_get_fd              = tls_socket_get_fd
};

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

#else

/* for systems without tls we just fail the operations, and the caller
 * will retain the original socket */

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

/*
  setup for a new connection
*/
struct socket_context *tls_init_server(struct tls_params *params, 
                                    struct socket_context *socket,
                                    struct tevent_fd *fde, 
                                    const char *plain_chars)
{
        return NULL;
}


/*
  setup for a new client connection
*/
struct socket_context *tls_init_client(struct socket_context *socket,
                                       struct tevent_fd *fde,
                                       const char *ca_path)
{
        return NULL;
}

bool tls_support(struct tls_params *params)
{
        return false;
}

#endif