source: vendor/3.6.0/source4/auth/gensec/socket.c

/* 
   Unix SMB/CIFS implementation.

   GENSEC socket interface

   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/stream/packet.h"
#include "auth/gensec/gensec.h"
#include "auth/gensec/gensec_proto.h"

static const struct socket_ops gensec_socket_ops;

struct gensec_socket {
        struct gensec_security *gensec_security;
        struct socket_context *socket;
        struct tevent_context *ev;
        struct packet_context *packet;
        DATA_BLOB read_buffer;  /* SASL packets are turned into liniarlised data here, for reading */
        size_t orig_send_len;
        bool eof;
        NTSTATUS error;
        bool interrupted;
        void (*recv_handler)(void *, uint16_t);
        void *recv_private;
        int in_extra_read;
        bool wrap; /* Should we be wrapping on this socket at all? */
};

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

        sock->backend_name = "gensec";

        return NT_STATUS_OK;
}

/* These functions are for use here only (public because SPNEGO must
 * use them for recursion) */
_PUBLIC_ NTSTATUS gensec_wrap_packets(struct gensec_security *gensec_security, 
                             TALLOC_CTX *mem_ctx, 
                             const DATA_BLOB *in, 
                             DATA_BLOB *out,
                             size_t *len_processed) 
{
        if (!gensec_security->ops->wrap_packets) {
                NTSTATUS nt_status;
                size_t max_input_size;
                DATA_BLOB unwrapped, wrapped;
                max_input_size = gensec_max_input_size(gensec_security);
                unwrapped = data_blob_const(in->data, MIN(max_input_size, (size_t)in->length));
                
                nt_status = gensec_wrap(gensec_security, 
                                        mem_ctx,
                                        &unwrapped, &wrapped);
                if (!NT_STATUS_IS_OK(nt_status)) {
                        return nt_status;
                }
                
                *out = data_blob_talloc(mem_ctx, NULL, 4);
                if (!out->data) {
                        return NT_STATUS_NO_MEMORY;
                }
                RSIVAL(out->data, 0, wrapped.length);
                
                if (!data_blob_append(mem_ctx, out, wrapped.data, wrapped.length)) {
                        return NT_STATUS_NO_MEMORY;
                }
                *len_processed = unwrapped.length;
                return NT_STATUS_OK;
        }
        return gensec_security->ops->wrap_packets(gensec_security, mem_ctx, in, out,
                                                  len_processed);
}

/* These functions are for use here only (public because SPNEGO must
 * use them for recursion) */
NTSTATUS gensec_unwrap_packets(struct gensec_security *gensec_security, 
                                        TALLOC_CTX *mem_ctx, 
                                        const DATA_BLOB *in, 
                                        DATA_BLOB *out,
                                        size_t *len_processed) 
{
        if (!gensec_security->ops->unwrap_packets) {
                DATA_BLOB wrapped;
                NTSTATUS nt_status;
                size_t packet_size;
                if (in->length < 4) {
                        /* Missing the header we already had! */
                        DEBUG(0, ("Asked to unwrap packet of bogus length!  How did we get the short packet?!\n"));
                        return NT_STATUS_INVALID_PARAMETER;
                }
                
                packet_size = RIVAL(in->data, 0);
                
                wrapped = data_blob_const(in->data + 4, packet_size);
                
                if (wrapped.length > (in->length - 4)) {
                        DEBUG(0, ("Asked to unwrap packed of bogus length %d > %d!  How did we get this?!\n",
                                  (int)wrapped.length, (int)(in->length - 4)));
                        return NT_STATUS_INTERNAL_ERROR;
                }
                
                nt_status = gensec_unwrap(gensec_security, 
                                          mem_ctx,
                                          &wrapped, out);
                if (!NT_STATUS_IS_OK(nt_status)) {
                        return nt_status;
                }
                
                *len_processed = packet_size + 4;
                return nt_status;
        }
        return gensec_security->ops->unwrap_packets(gensec_security, mem_ctx, in, out,
                                                    len_processed);
}

/* These functions are for use here only (public because SPNEGO must
 * use them for recursion) */
NTSTATUS gensec_packet_full_request(struct gensec_security *gensec_security,
                                    DATA_BLOB blob, size_t *size) 
{
        if (gensec_security->ops->packet_full_request) {
                return gensec_security->ops->packet_full_request(gensec_security,
                                                                 blob, size);
        }
        if (gensec_security->ops->unwrap_packets) {
                if (blob.length) {
                        *size = blob.length;
                        return NT_STATUS_OK;
                }
                return STATUS_MORE_ENTRIES;
        }
        return packet_full_request_u32(NULL, blob, size);
}

static NTSTATUS gensec_socket_full_request(void *private_data, DATA_BLOB blob, size_t *size)
{
        struct gensec_socket *gensec_socket = talloc_get_type(private_data, struct gensec_socket);
        struct gensec_security *gensec_security = gensec_socket->gensec_security;
        return gensec_packet_full_request(gensec_security, blob, size);
}

/* Try to figure out how much data is waiting to be read */
static NTSTATUS gensec_socket_pending(struct socket_context *sock, size_t *npending) 
{
        struct gensec_socket *gensec_socket = talloc_get_type(sock->private_data, struct gensec_socket);
        if (!gensec_socket->wrap) {
                return socket_pending(gensec_socket->socket, npending);
        }

        if (gensec_socket->read_buffer.length > 0) {
                *npending = gensec_socket->read_buffer.length;
                return NT_STATUS_OK;
        }

        /* This is a lie.  We hope the decrypted data will always be
         * less than this value, so the application just gets a short
         * read.  Without reading and decrypting it, we can't tell.
         * If the SASL mech does compression, then we just need to
         * manually trigger read events */
        return socket_pending(gensec_socket->socket, npending);
}      

/* Note if an error occours, so we can return it up the stack */
static void gensec_socket_error_handler(void *private_data, NTSTATUS status)
{
        struct gensec_socket *gensec_socket = talloc_get_type(private_data, struct gensec_socket);
        if (NT_STATUS_EQUAL(status, NT_STATUS_END_OF_FILE)) {
                gensec_socket->eof = true;
        } else {
                gensec_socket->error = status;
        }
}

static void gensec_socket_trigger_read(struct tevent_context *ev, 
                                       struct tevent_timer *te, 
                                       struct timeval t, void *private_data)
{
        struct gensec_socket *gensec_socket = talloc_get_type(private_data, struct gensec_socket);

        gensec_socket->in_extra_read++;
        gensec_socket->recv_handler(gensec_socket->recv_private, EVENT_FD_READ);
        gensec_socket->in_extra_read--;

        /* It may well be that, having run the recv handler, we still
         * have even more data waiting for us! 
         */
        if (gensec_socket->read_buffer.length && gensec_socket->recv_handler) {
                /* Schedule this funcion to run again */
                event_add_timed(gensec_socket->ev, gensec_socket, timeval_zero(), 
                                gensec_socket_trigger_read, gensec_socket);
        }
}

/* These two routines could be changed to use a circular buffer of
 * some kind, or linked lists, or ... */
static NTSTATUS gensec_socket_recv(struct socket_context *sock, void *buf,
                                   size_t wantlen, size_t *nread) 
{
        struct gensec_socket *gensec_socket = talloc_get_type(sock->private_data, struct gensec_socket);

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

        gensec_socket->error = NT_STATUS_OK;

        if (gensec_socket->read_buffer.length == 0) {
                /* Process any data on the socket, into the read buffer. At
                 * this point, the socket is not available for read any
                 * longer */
                packet_recv(gensec_socket->packet);

                if (gensec_socket->eof) {
                        *nread = 0;
                        return NT_STATUS_OK;
                }
                
                if (!NT_STATUS_IS_OK(gensec_socket->error)) {
                        return gensec_socket->error;
                }

                if (gensec_socket->read_buffer.length == 0) {
                        /* Clearly we don't have the entire SASL packet yet,
                         * so it has not been written into the buffer */
                        *nread = 0;
                        return STATUS_MORE_ENTRIES;
                }
        }


        *nread = MIN(wantlen, gensec_socket->read_buffer.length);
        memcpy(buf, gensec_socket->read_buffer.data, *nread);

        if (gensec_socket->read_buffer.length > *nread) {
                memmove(gensec_socket->read_buffer.data, 
                        gensec_socket->read_buffer.data + *nread, 
                        gensec_socket->read_buffer.length - *nread);
        }

        gensec_socket->read_buffer.length -= *nread;
        gensec_socket->read_buffer.data = talloc_realloc(gensec_socket, 
                                                         gensec_socket->read_buffer.data, 
                                                         uint8_t, 
                                                         gensec_socket->read_buffer.length);

        if (gensec_socket->read_buffer.length && 
            gensec_socket->in_extra_read == 0 && 
            gensec_socket->recv_handler) {
                /* Manually call a read event, to get this moving
                 * again (as the socket should be dry, so the normal
                 * event handler won't trigger) */
                event_add_timed(gensec_socket->ev, gensec_socket, timeval_zero(), 
                                gensec_socket_trigger_read, gensec_socket);
        }

        return NT_STATUS_OK;
}

/* Completed SASL packet callback.  When we have a 'whole' SASL
 * packet, decrypt it, and add it to the read buffer
 *
 * This function (and anything under it) MUST NOT call the event system
 */
static NTSTATUS gensec_socket_unwrap(void *private_data, DATA_BLOB blob)
{
        struct gensec_socket *gensec_socket = talloc_get_type(private_data, struct gensec_socket);
        DATA_BLOB unwrapped;
        NTSTATUS nt_status;
        TALLOC_CTX *mem_ctx;
        size_t packet_size;

        mem_ctx = talloc_new(gensec_socket);
        if (!mem_ctx) {
                return NT_STATUS_NO_MEMORY;
        }
        nt_status = gensec_unwrap_packets(gensec_socket->gensec_security, 
                                          mem_ctx,
                                          &blob, &unwrapped, 
                                          &packet_size);
        if (!NT_STATUS_IS_OK(nt_status)) {
                talloc_free(mem_ctx);
                return nt_status;
        }

        if (packet_size != blob.length) {
                DEBUG(0, ("gensec_socket_unwrap: Did not consume entire packet!\n"));
                talloc_free(mem_ctx);
                return NT_STATUS_INTERNAL_ERROR;
        }

        /* We could change this into a linked list, and have
         * gensec_socket_recv() and gensec_socket_pending() walk the
         * linked list */

        if (!data_blob_append(gensec_socket, &gensec_socket->read_buffer, 
                                     unwrapped.data, unwrapped.length)) {
                talloc_free(mem_ctx);
                return NT_STATUS_NO_MEMORY;
        }

        talloc_free(mem_ctx);
        return NT_STATUS_OK;
}

/* when the data is sent, we know we have not been interrupted */
static void send_callback(void *private_data)
{
        struct gensec_socket *gensec_socket = talloc_get_type(private_data, struct gensec_socket);
        gensec_socket->interrupted = false;
}

/*
  send data, but only as much as we allow in one packet.  

  If this returns STATUS_MORE_ENTRIES, the caller must retry with
  exactly the same data, or a NULL blob.
*/
static NTSTATUS gensec_socket_send(struct socket_context *sock, 
                                   const DATA_BLOB *blob, size_t *sendlen)
{
        NTSTATUS nt_status;
        struct gensec_socket *gensec_socket = talloc_get_type(sock->private_data, struct gensec_socket);
        DATA_BLOB wrapped;
        TALLOC_CTX *mem_ctx;

        if (!gensec_socket->wrap) {
                return socket_send(gensec_socket->socket, blob, sendlen);
        }

        *sendlen = 0;

        /* We have have been interupted, so the caller should be
         * giving us the same data again.  */
        if (gensec_socket->interrupted) {
                packet_queue_run(gensec_socket->packet);

                if (!NT_STATUS_IS_OK(gensec_socket->error)) {
                        return gensec_socket->error;
                } else if (gensec_socket->interrupted) {
                        return STATUS_MORE_ENTRIES;
                } else {
                        *sendlen = gensec_socket->orig_send_len;
                        gensec_socket->orig_send_len = 0;
                        return NT_STATUS_OK;
                }
        }

        mem_ctx = talloc_new(gensec_socket);
        if (!mem_ctx) {
                return NT_STATUS_NO_MEMORY;
        }

        nt_status = gensec_wrap_packets(gensec_socket->gensec_security, 
                                        mem_ctx,
                                        blob, &wrapped, 
                                        &gensec_socket->orig_send_len);
        if (!NT_STATUS_IS_OK(nt_status)) {
                talloc_free(mem_ctx);
                return nt_status;
        }
        
        gensec_socket->interrupted = true;
        gensec_socket->error = NT_STATUS_OK;

        nt_status = packet_send_callback(gensec_socket->packet, 
                                         wrapped,
                                         send_callback, gensec_socket);

        talloc_free(mem_ctx);

        packet_queue_run(gensec_socket->packet);

        if (!NT_STATUS_IS_OK(gensec_socket->error)) {
                return gensec_socket->error;
        } else if (gensec_socket->interrupted) {
                return STATUS_MORE_ENTRIES;
        } else {
                *sendlen = gensec_socket->orig_send_len;
                gensec_socket->orig_send_len = 0;
                return NT_STATUS_OK;
        }
}

/* Turn a normal socket into a potentially GENSEC wrapped socket */
/* CAREFUL: this function will steal 'current_socket' */

NTSTATUS gensec_socket_init(struct gensec_security *gensec_security,
                            TALLOC_CTX *mem_ctx,
                            struct socket_context *current_socket,
                            struct tevent_context *ev,
                            void (*recv_handler)(void *, uint16_t),
                            void *recv_private,
                            struct socket_context **new_socket)
{
        struct gensec_socket *gensec_socket;
        struct socket_context *new_sock;
        NTSTATUS nt_status;

        nt_status = socket_create_with_ops(mem_ctx, &gensec_socket_ops, &new_sock, 
                                           SOCKET_TYPE_STREAM, current_socket->flags | SOCKET_FLAG_ENCRYPT);
        if (!NT_STATUS_IS_OK(nt_status)) {
                *new_socket = NULL;
                return nt_status;
        }

        new_sock->state = current_socket->state;

        gensec_socket = talloc(new_sock, struct gensec_socket);
        if (gensec_socket == NULL) {
                *new_socket = NULL;
                talloc_free(new_sock);
                return NT_STATUS_NO_MEMORY;
        }

        new_sock->private_data       = gensec_socket;
        gensec_socket->socket        = current_socket;

        /* Nothing to do here, if we are not actually wrapping on this socket */
        if (!gensec_have_feature(gensec_security, GENSEC_FEATURE_SEAL) &&
            !gensec_have_feature(gensec_security, GENSEC_FEATURE_SIGN)) {
                
                gensec_socket->wrap = false;
                talloc_steal(gensec_socket, current_socket);
                *new_socket = new_sock;
                return NT_STATUS_OK;
        }

        gensec_socket->gensec_security = gensec_security;

        gensec_socket->wrap          = true;
        gensec_socket->eof           = false;
        gensec_socket->error         = NT_STATUS_OK;
        gensec_socket->interrupted   = false;
        gensec_socket->in_extra_read = 0;

        gensec_socket->read_buffer   = data_blob(NULL, 0);

        gensec_socket->recv_handler  = recv_handler;
        gensec_socket->recv_private  = recv_private;
        gensec_socket->ev            = ev;

        gensec_socket->packet = packet_init(gensec_socket);
        if (gensec_socket->packet == NULL) {
                *new_socket = NULL;
                talloc_free(new_sock);
                return NT_STATUS_NO_MEMORY;
        }

        packet_set_private(gensec_socket->packet, gensec_socket);
        packet_set_socket(gensec_socket->packet, gensec_socket->socket);
        packet_set_callback(gensec_socket->packet, gensec_socket_unwrap);
        packet_set_full_request(gensec_socket->packet, gensec_socket_full_request);
        packet_set_error_handler(gensec_socket->packet, gensec_socket_error_handler);
        packet_set_serialise(gensec_socket->packet);

        /* TODO: full-request that knows about maximum packet size */

        talloc_steal(gensec_socket, current_socket);
        *new_socket = new_sock;
        return NT_STATUS_OK;
}


static NTSTATUS gensec_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 *gensec_socket_get_peer_name(struct socket_context *sock, TALLOC_CTX *mem_ctx)
{
        struct gensec_socket *gensec = talloc_get_type(sock->private_data, struct gensec_socket);
        return socket_get_peer_name(gensec->socket, mem_ctx);
}

static struct socket_address *gensec_socket_get_peer_addr(struct socket_context *sock, TALLOC_CTX *mem_ctx)
{
        struct gensec_socket *gensec = talloc_get_type(sock->private_data, struct gensec_socket);
        return socket_get_peer_addr(gensec->socket, mem_ctx);
}

static struct socket_address *gensec_socket_get_my_addr(struct socket_context *sock, TALLOC_CTX *mem_ctx)
{
        struct gensec_socket *gensec = talloc_get_type(sock->private_data, struct gensec_socket);
        return socket_get_my_addr(gensec->socket, mem_ctx);
}

static int gensec_socket_get_fd(struct socket_context *sock)
{
        struct gensec_socket *gensec = talloc_get_type(sock->private_data, struct gensec_socket);
        return socket_get_fd(gensec->socket);
}

static const struct socket_ops gensec_socket_ops = {
        .name                   = "gensec",
        .fn_init                = gensec_socket_init_fn,
        .fn_recv                = gensec_socket_recv,
        .fn_send                = gensec_socket_send,
        .fn_pending             = gensec_socket_pending,

        .fn_set_option          = gensec_socket_set_option,

        .fn_get_peer_name       = gensec_socket_get_peer_name,
        .fn_get_peer_addr       = gensec_socket_get_peer_addr,
        .fn_get_my_addr         = gensec_socket_get_my_addr,
        .fn_get_fd              = gensec_socket_get_fd
};