source: vendor/3.5.5/source4/libcli/smb2/session.c

/* 
   Unix SMB/CIFS implementation.

   SMB2 client session handling

   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 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 "libcli/raw/libcliraw.h"
#include "libcli/smb2/smb2.h"
#include "libcli/smb2/smb2_calls.h"
#include "libcli/composite/composite.h"
#include "auth/gensec/gensec.h"

/**
  initialise a smb2_session structure
 */
struct smb2_session *smb2_session_init(struct smb2_transport *transport,
                                       struct gensec_settings *settings,
                                       TALLOC_CTX *parent_ctx, bool primary)
{
        struct smb2_session *session;
        NTSTATUS status;

        session = talloc_zero(parent_ctx, struct smb2_session);
        if (!session) {
                return NULL;
        }
        if (primary) {
                session->transport = talloc_steal(session, transport);
        } else {
                session->transport = talloc_reference(session, transport);
        }

        /* prepare a gensec context for later use */
        status = gensec_client_start(session, &session->gensec, 
                                     session->transport->socket->event.ctx, 
                                     settings);
        if (!NT_STATUS_IS_OK(status)) {
                talloc_free(session);
                return NULL;
        }

        gensec_want_feature(session->gensec, GENSEC_FEATURE_SESSION_KEY);

        return session;
}

/**
  send a session setup request
*/
struct smb2_request *smb2_session_setup_send(struct smb2_session *session, 
                                             struct smb2_session_setup *io)
{
        struct smb2_request *req;
        NTSTATUS status;
        
        req = smb2_request_init(session->transport, SMB2_OP_SESSSETUP, 
                                0x18, true, io->in.secblob.length);
        if (req == NULL) return NULL;

        SBVAL(req->out.hdr,  SMB2_HDR_SESSION_ID, session->uid);
        SCVAL(req->out.body, 0x02, io->in.vc_number);
        SCVAL(req->out.body, 0x03, io->in.security_mode);
        SIVAL(req->out.body, 0x04, io->in.capabilities);
        SIVAL(req->out.body, 0x08, io->in.channel);
        SBVAL(req->out.body, 0x10, io->in.previous_sessionid);

        req->session = session;

        status = smb2_push_o16s16_blob(&req->out, 0x0C, io->in.secblob);
        if (!NT_STATUS_IS_OK(status)) {
                talloc_free(req);
                return NULL;
        }

        smb2_transport_send(req);

        return req;
}


/**
  recv a session setup reply
*/
NTSTATUS smb2_session_setup_recv(struct smb2_request *req, TALLOC_CTX *mem_ctx, 
                                 struct smb2_session_setup *io)
{
        NTSTATUS status;

        if (!smb2_request_receive(req) || 
            (smb2_request_is_error(req) && 
             !NT_STATUS_EQUAL(req->status, NT_STATUS_MORE_PROCESSING_REQUIRED))) {
                return smb2_request_destroy(req);
        }

        SMB2_CHECK_PACKET_RECV(req, 0x08, true);

        io->out.session_flags = SVAL(req->in.body, 0x02);
        io->out.uid           = BVAL(req->in.hdr,  SMB2_HDR_SESSION_ID);
        
        status = smb2_pull_o16s16_blob(&req->in, mem_ctx, req->in.body+0x04, &io->out.secblob);
        if (!NT_STATUS_IS_OK(status)) {
                smb2_request_destroy(req);
                return status;
        }

        return smb2_request_destroy(req);
}

/*
  sync session setup request
*/
NTSTATUS smb2_session_setup(struct smb2_session *session, 
                            TALLOC_CTX *mem_ctx, struct smb2_session_setup *io)
{
        struct smb2_request *req = smb2_session_setup_send(session, io);
        return smb2_session_setup_recv(req, mem_ctx, io);
}


struct smb2_session_state {
        struct smb2_session_setup io;
        struct smb2_request *req;
        NTSTATUS gensec_status;
};

/*
  handle continuations of the spnego session setup
*/
static void session_request_handler(struct smb2_request *req)
{
        struct composite_context *c = talloc_get_type(req->async.private_data, 
                                                      struct composite_context);
        struct smb2_session_state *state = talloc_get_type(c->private_data, 
                                                           struct smb2_session_state);
        struct smb2_session *session = req->session;
        NTSTATUS session_key_err;
        DATA_BLOB session_key;
        NTSTATUS peer_status;

        c->status = smb2_session_setup_recv(req, c, &state->io);
        peer_status = c->status;

        if (NT_STATUS_EQUAL(peer_status, NT_STATUS_MORE_PROCESSING_REQUIRED) ||
            (NT_STATUS_IS_OK(peer_status) &&
             NT_STATUS_EQUAL(state->gensec_status, NT_STATUS_MORE_PROCESSING_REQUIRED))) {
                c->status = gensec_update(session->gensec, c, 
                                          state->io.out.secblob,
                                          &state->io.in.secblob);
                state->gensec_status = c->status;

                session->uid = state->io.out.uid;
        }

        if (!NT_STATUS_IS_OK(c->status) &&
            !NT_STATUS_EQUAL(c->status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
                composite_error(c, c->status);
                return;
        }

        if (NT_STATUS_EQUAL(peer_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
                state->req = smb2_session_setup_send(session, &state->io);
                if (state->req == NULL) {
                        composite_error(c, NT_STATUS_NO_MEMORY);
                        return;
                }

                state->req->async.fn = session_request_handler;
                state->req->async.private_data = c;
                return;
        }

        session_key_err = gensec_session_key(session->gensec, &session_key);
        if (NT_STATUS_IS_OK(session_key_err)) {
                session->session_key = session_key;
        }

        if (session->transport->signing_required) {
                if (session->session_key.length == 0) {
                        DEBUG(0,("Wrong session key length %u for SMB2 signing\n",
                                 (unsigned)session->session_key.length));
                        composite_error(c, NT_STATUS_ACCESS_DENIED);
                        return;
                }
                session->signing_active = true;
        }

        composite_done(c);
}

/*
  a composite function that does a full SPNEGO session setup
 */
struct composite_context *smb2_session_setup_spnego_send(struct smb2_session *session, 
                                                         struct cli_credentials *credentials)
{
        struct composite_context *c;
        struct smb2_session_state *state;
        const char *chosen_oid;

        c = composite_create(session, session->transport->socket->event.ctx);
        if (c == NULL) return NULL;

        state = talloc(c, struct smb2_session_state);
        if (composite_nomem(state, c)) return c;
        c->private_data = state;

        ZERO_STRUCT(state->io);
        state->io.in.vc_number          = 0;
        if (session->transport->signing_required) {
                state->io.in.security_mode = 
                        SMB2_NEGOTIATE_SIGNING_ENABLED | SMB2_NEGOTIATE_SIGNING_REQUIRED;
        }
        state->io.in.capabilities       = 0;
        state->io.in.channel            = 0;
        state->io.in.previous_sessionid = 0;

        c->status = gensec_set_credentials(session->gensec, credentials);
        if (!composite_is_ok(c)) return c;

        c->status = gensec_set_target_hostname(session->gensec, 
                                               session->transport->socket->hostname);
        if (!composite_is_ok(c)) return c;

        c->status = gensec_set_target_service(session->gensec, "cifs");
        if (!composite_is_ok(c)) return c;

        if (session->transport->negotiate.secblob.length > 0) {
                chosen_oid = GENSEC_OID_SPNEGO;
        } else {
                chosen_oid = GENSEC_OID_NTLMSSP;
        }

        c->status = gensec_start_mech_by_oid(session->gensec, chosen_oid);
        if (!composite_is_ok(c)) return c;

        c->status = gensec_update(session->gensec, c, 
                                  session->transport->negotiate.secblob,
                                  &state->io.in.secblob);
        if (!NT_STATUS_EQUAL(c->status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
                composite_error(c, c->status);
                return c;
        }
        state->gensec_status = c->status;
                
        state->req = smb2_session_setup_send(session, &state->io);
        composite_continue_smb2(c, state->req, session_request_handler, c);
        return c;
}

/*
  receive a composite session setup reply
*/
NTSTATUS smb2_session_setup_spnego_recv(struct composite_context *c)
{
        NTSTATUS status;
        status = composite_wait(c);
        talloc_free(c);
        return status;
}

/*
  sync version of smb2_session_setup_spnego
*/
NTSTATUS smb2_session_setup_spnego(struct smb2_session *session, 
                                   struct cli_credentials *credentials)
{
        struct composite_context *c = smb2_session_setup_spnego_send(session, credentials);
        return smb2_session_setup_spnego_recv(c);
}