opendb_tdb.c

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/* 
   Unix SMB/CIFS implementation.

   Copyright (C) Andrew Tridgell 2004
   Copyright (C) Stefan Metzmacher 2008

   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/>.
*/

/*
  this is the open files database, tdb backend. It implements shared
  storage of what files are open between server instances, and
  implements the rules of shared access to files.

  The caller needs to provide a file_key, which specifies what file
  they are talking about. This needs to be a unique key across all
  filesystems, and is usually implemented in terms of a device/inode
  pair.

  Before any operations can be performed the caller needs to establish
  a lock on the record associated with file_key. That is done by
  calling odb_lock(). The caller releases this lock by calling
  talloc_free() on the returned handle.

  All other operations on a record are done by passing the odb_lock()
  handle back to this module. The handle contains internal
  information about what file_key is being operated on.
*/

#include "includes.h"
#include "system/filesys.h"
#include "lib/tdb/include/tdb.h"
#include "messaging/messaging.h"
#include "tdb_wrap.h"
#include "lib/messaging/irpc.h"
#include "librpc/gen_ndr/ndr_opendb.h"
#include "ntvfs/ntvfs.h"
#include "ntvfs/common/ntvfs_common.h"
#include "cluster/cluster.h"
#include "param/param.h"
#include "ntvfs/sysdep/sys_lease.h"

struct odb_context {
	struct tdb_wrap *w;
	struct ntvfs_context *ntvfs_ctx;
	bool oplocks;
	struct sys_lease_context *lease_ctx;
};

/*
  an odb lock handle. You must obtain one of these using odb_lock() before doing
  any other operations. 
*/
struct odb_lock {
	struct odb_context *odb;
	TDB_DATA key;

	struct opendb_file file;

	struct {
		struct opendb_entry *e;
		bool attrs_only;
	} can_open;
};

static NTSTATUS odb_oplock_break_send(struct messaging_context *msg_ctx,
				      struct opendb_entry *e,
				      uint8_t level);

/*
  Open up the openfiles.tdb database. Close it down using
  talloc_free(). We need the messaging_ctx to allow for pending open
  notifications.
*/
static struct odb_context *odb_tdb_init(TALLOC_CTX *mem_ctx, 
					struct ntvfs_context *ntvfs_ctx)
{
	struct odb_context *odb;

	odb = talloc(mem_ctx, struct odb_context);
	if (odb == NULL) {
		return NULL;
	}

	odb->w = cluster_tdb_tmp_open(odb, ntvfs_ctx->lp_ctx, "openfiles.tdb", TDB_DEFAULT);
	if (odb->w == NULL) {
		talloc_free(odb);
		return NULL;
	}

	odb->ntvfs_ctx = ntvfs_ctx;

	odb->oplocks = share_bool_option(ntvfs_ctx->config, SHARE_OPLOCKS, SHARE_OPLOCKS_DEFAULT);

	odb->lease_ctx = sys_lease_context_create(ntvfs_ctx->config, odb,
						  ntvfs_ctx->event_ctx,
						  ntvfs_ctx->msg_ctx,
						  odb_oplock_break_send);

	return odb;
}

/*
  destroy a lock on the database
*/
static int odb_lock_destructor(struct odb_lock *lck)
{
	tdb_chainunlock(lck->odb->w->tdb, lck->key);
	return 0;
}

static NTSTATUS odb_pull_record(struct odb_lock *lck, struct opendb_file *file);

/*
  get a lock on a entry in the odb. This call returns a lock handle,
  which the caller should unlock using talloc_free().
*/
static struct odb_lock *odb_tdb_lock(TALLOC_CTX *mem_ctx,
				     struct odb_context *odb, DATA_BLOB *file_key)
{
	struct odb_lock *lck;
	NTSTATUS status;

	lck = talloc(mem_ctx, struct odb_lock);
	if (lck == NULL) {
		return NULL;
	}

	lck->odb = talloc_reference(lck, odb);
	lck->key.dptr = talloc_memdup(lck, file_key->data, file_key->length);
	lck->key.dsize = file_key->length;
	if (lck->key.dptr == NULL) {
		talloc_free(lck);
		return NULL;
	}

	if (tdb_chainlock(odb->w->tdb, lck->key) != 0) {
		talloc_free(lck);
		return NULL;
	}

	ZERO_STRUCT(lck->can_open);

	talloc_set_destructor(lck, odb_lock_destructor);

	status = odb_pull_record(lck, &lck->file);
	if (NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
		/* initialise a blank structure */
		ZERO_STRUCT(lck->file);
	} else if (!NT_STATUS_IS_OK(status)) {
		talloc_free(lck);
		return NULL;
	}
	
	return lck;
}

static DATA_BLOB odb_tdb_get_key(TALLOC_CTX *mem_ctx, struct odb_lock *lck)
{
	return data_blob_talloc(mem_ctx, lck->key.dptr, lck->key.dsize);
}


/*
  determine if two odb_entry structures conflict

  return NT_STATUS_OK on no conflict
*/
static NTSTATUS share_conflict(struct opendb_entry *e1,
			       uint32_t stream_id,
			       uint32_t share_access,
			       uint32_t access_mask)
{
	/* if either open involves no read.write or delete access then
	   it can't conflict */
	if (!(e1->access_mask & (SEC_FILE_WRITE_DATA |
				 SEC_FILE_APPEND_DATA |
				 SEC_FILE_READ_DATA |
				 SEC_FILE_EXECUTE |
				 SEC_STD_DELETE))) {
		return NT_STATUS_OK;
	}
	if (!(access_mask & (SEC_FILE_WRITE_DATA |
			     SEC_FILE_APPEND_DATA |
			     SEC_FILE_READ_DATA |
			     SEC_FILE_EXECUTE |
			     SEC_STD_DELETE))) {
		return NT_STATUS_OK;
	}

	/* data IO access masks. This is skipped if the two open handles
	   are on different streams (as in that case the masks don't
	   interact) */
	if (e1->stream_id != stream_id) {
		return NT_STATUS_OK;
	}

#define CHECK_MASK(am, right, sa, share) \
	if (((am) & (right)) && !((sa) & (share))) return NT_STATUS_SHARING_VIOLATION

	CHECK_MASK(e1->access_mask, SEC_FILE_WRITE_DATA | SEC_FILE_APPEND_DATA,
		   share_access, NTCREATEX_SHARE_ACCESS_WRITE);
	CHECK_MASK(access_mask, SEC_FILE_WRITE_DATA | SEC_FILE_APPEND_DATA,
		   e1->share_access, NTCREATEX_SHARE_ACCESS_WRITE);
	
	CHECK_MASK(e1->access_mask, SEC_FILE_READ_DATA | SEC_FILE_EXECUTE,
		   share_access, NTCREATEX_SHARE_ACCESS_READ);
	CHECK_MASK(access_mask, SEC_FILE_READ_DATA | SEC_FILE_EXECUTE,
		   e1->share_access, NTCREATEX_SHARE_ACCESS_READ);

	CHECK_MASK(e1->access_mask, SEC_STD_DELETE,
		   share_access, NTCREATEX_SHARE_ACCESS_DELETE);
	CHECK_MASK(access_mask, SEC_STD_DELETE,
		   e1->share_access, NTCREATEX_SHARE_ACCESS_DELETE);
#undef CHECK_MASK
	return NT_STATUS_OK;
}

/*
  pull a record, translating from the db format to the opendb_file structure defined
  in opendb.idl
*/
static NTSTATUS odb_pull_record(struct odb_lock *lck, struct opendb_file *file)
{
	struct odb_context *odb = lck->odb;
	TDB_DATA dbuf;
	DATA_BLOB blob;
	enum ndr_err_code ndr_err;

	dbuf = tdb_fetch(odb->w->tdb, lck->key);
	if (dbuf.dptr == NULL) {
		return NT_STATUS_OBJECT_NAME_NOT_FOUND;
	}

	blob.data = dbuf.dptr;
	blob.length = dbuf.dsize;

	ndr_err = ndr_pull_struct_blob(&blob, lck, lp_iconv_convenience(lck->odb->ntvfs_ctx->lp_ctx), file, (ndr_pull_flags_fn_t)ndr_pull_opendb_file);
	free(dbuf.dptr);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		return ndr_map_error2ntstatus(ndr_err);
	}

	return NT_STATUS_OK;
}

/*
  push a record, translating from the opendb_file structure defined in opendb.idl
*/
static NTSTATUS odb_push_record(struct odb_lock *lck, struct opendb_file *file)
{
	struct odb_context *odb = lck->odb;
	TDB_DATA dbuf;
	DATA_BLOB blob;
	enum ndr_err_code ndr_err;
	int ret;

	if (file->num_entries == 0) {
		ret = tdb_delete(odb->w->tdb, lck->key);
		if (ret != 0) {
			return NT_STATUS_INTERNAL_DB_CORRUPTION;
		}
		return NT_STATUS_OK;
	}

	ndr_err = ndr_push_struct_blob(&blob, lck, lp_iconv_convenience(lck->odb->ntvfs_ctx->lp_ctx), file, (ndr_push_flags_fn_t)ndr_push_opendb_file);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		return ndr_map_error2ntstatus(ndr_err);
	}

	dbuf.dptr = blob.data;
	dbuf.dsize = blob.length;
		
	ret = tdb_store(odb->w->tdb, lck->key, dbuf, TDB_REPLACE);
	data_blob_free(&blob);
	if (ret != 0) {
		return NT_STATUS_INTERNAL_DB_CORRUPTION;
	}

	return NT_STATUS_OK;
}

/*
  send an oplock break to a client
*/
static NTSTATUS odb_oplock_break_send(struct messaging_context *msg_ctx,
				      struct opendb_entry *e,
				      uint8_t level)
{
	NTSTATUS status;
	struct opendb_oplock_break op_break;
	DATA_BLOB blob;

	ZERO_STRUCT(op_break);

	/* tell the server handling this open file about the need to send the client
	   a break */
	op_break.file_handle	= e->file_handle;
	op_break.level		= level;

	blob = data_blob_const(&op_break, sizeof(op_break));

	status = messaging_send(msg_ctx, e->server,
				MSG_NTVFS_OPLOCK_BREAK, &blob);
	NT_STATUS_NOT_OK_RETURN(status);

	return NT_STATUS_OK;
}

static bool access_attributes_only(uint32_t access_mask,
				   uint32_t open_disposition,
				   bool break_to_none)
{
	switch (open_disposition) {
	case NTCREATEX_DISP_SUPERSEDE:
	case NTCREATEX_DISP_OVERWRITE_IF:
	case NTCREATEX_DISP_OVERWRITE:
		return false;
	default:
		break;
	}

	if (break_to_none) {
		return false;
	}

#define CHECK_MASK(m,g) ((m) && (((m) & ~(g))==0) && (((m) & (g)) != 0))
	return CHECK_MASK(access_mask,
			  SEC_STD_SYNCHRONIZE |
			  SEC_FILE_READ_ATTRIBUTE |
			  SEC_FILE_WRITE_ATTRIBUTE);
#undef CHECK_MASK
}

static NTSTATUS odb_tdb_open_can_internal(struct odb_context *odb,
					  const struct opendb_file *file,
					  uint32_t stream_id, uint32_t share_access,
					  uint32_t access_mask, bool delete_on_close,
					  uint32_t open_disposition, bool break_to_none,
					  bool *_attrs_only)
{
	NTSTATUS status;
	uint32_t i;
	bool attrs_only = false;

	/* see if anyone has an oplock, which we need to break */
	for (i=0;i<file->num_entries;i++) {
		if (file->entries[i].oplock_level == OPLOCK_BATCH) {
			bool oplock_return = OPLOCK_BREAK_TO_LEVEL_II;
			/* if this is an attribute only access
			 * it doesn't conflict with a BACTCH oplock
			 * but we'll not grant the oplock below
			 */
			attrs_only = access_attributes_only(access_mask,
							    open_disposition,
							    break_to_none);
			if (attrs_only) {
				break;
			}
			/* a batch oplock caches close calls, which
			   means the client application might have
			   already closed the file. We have to allow
			   this close to propogate by sending a oplock
			   break request and suspending this call
			   until the break is acknowledged or the file
			   is closed */
			if (break_to_none ||
			    !file->entries[i].allow_level_II_oplock) {
				oplock_return = OPLOCK_BREAK_TO_NONE;
			}
			odb_oplock_break_send(odb->ntvfs_ctx->msg_ctx,
					      &file->entries[i],
					      oplock_return);
			return NT_STATUS_OPLOCK_NOT_GRANTED;
		}
	}

	if (file->delete_on_close) {
		/* while delete on close is set, no new opens are allowed */
		return NT_STATUS_DELETE_PENDING;
	}

	if (file->num_entries != 0 && delete_on_close) {
		return NT_STATUS_SHARING_VIOLATION;
	}

	/* check for sharing violations */
	for (i=0;i<file->num_entries;i++) {
		status = share_conflict(&file->entries[i], stream_id,
					share_access, access_mask);
		NT_STATUS_NOT_OK_RETURN(status);
	}

	/* we now know the open could succeed, but we need to check
	   for any exclusive oplocks. We can't grant a second open
	   till these are broken. Note that we check for batch oplocks
	   before checking for sharing violations, and check for
	   exclusive oplocks afterwards. */
	for (i=0;i<file->num_entries;i++) {
		if (file->entries[i].oplock_level == OPLOCK_EXCLUSIVE) {
			bool oplock_return = OPLOCK_BREAK_TO_LEVEL_II;
			/* if this is an attribute only access
			 * it doesn't conflict with an EXCLUSIVE oplock
			 * but we'll not grant the oplock below
			 */
			attrs_only = access_attributes_only(access_mask,
							    open_disposition,
							    break_to_none);
			if (attrs_only) {
				break;
			}
			/*
			 * send an oplock break to the holder of the
			 * oplock and tell caller to retry later
			 */
			if (break_to_none ||
			    !file->entries[i].allow_level_II_oplock) {
				oplock_return = OPLOCK_BREAK_TO_NONE;
			}
			odb_oplock_break_send(odb->ntvfs_ctx->msg_ctx,
					      &file->entries[i],
					      oplock_return);
			return NT_STATUS_OPLOCK_NOT_GRANTED;