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leases_db: Make leases_db_rename atomic

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Do the rename under one lock to protect against potential races while
we don't hold it.

Factor out the NDR marshalling into leases_db_do_locked(), leaving the
rename function pretty simple.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
This commit is contained in:
Volker Lendecke 2019-04-08 15:18:31 +02:00 committed by Jeremy Allison
parent cc4513dd4d
commit ee53763a3e
1 changed files with 153 additions and 10 deletions
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163
source3/locking/leases_db.c
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@ -86,6 +86,114 @@ static TDB_DATA leases_db_key(struct leases_db_key_buf *buf,
return (TDB_DATA) { .dptr = buf->buf, .dsize = sizeof(buf->buf) };
}
struct leases_db_do_locked_state {
void (*fn)(struct leases_db_value *value,
bool *modified,
void *private_data);
void *private_data;
NTSTATUS status;
};
static void leases_db_do_locked_fn(struct db_record *rec, void *private_data)
{
struct leases_db_do_locked_state *state = private_data;
TDB_DATA db_value = dbwrap_record_get_value(rec);
DATA_BLOB blob = { .data = db_value.dptr, .length = db_value.dsize };
struct leases_db_value *value = NULL;
enum ndr_err_code ndr_err;
bool modified = false;
value = talloc_zero(talloc_tos(), struct leases_db_value);
if (value == NULL) {
state->status = NT_STATUS_NO_MEMORY;
goto done;
}
if (blob.length != 0) {
ndr_err = ndr_pull_struct_blob_all(
&blob,
value,
value,
(ndr_pull_flags_fn_t)ndr_pull_leases_db_value);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
DBG_DEBUG("ndr_pull_struct_blob_failed: %s\n",
ndr_errstr(ndr_err));
state->status = ndr_map_error2ntstatus(ndr_err);
goto done;
}
}
state->fn(value, &modified, state->private_data);
if (!modified) {
goto done;
}
if (value->num_files == 0) {
state->status = dbwrap_record_delete(rec);
if (!NT_STATUS_IS_OK(state->status)) {
DBG_DEBUG("dbwrap_record_delete returned %s\n",
nt_errstr(state->status));
}
goto done;
}
ndr_err = ndr_push_struct_blob(
&blob,
value,
value,
(ndr_push_flags_fn_t)ndr_push_leases_db_value);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
DBG_DEBUG("ndr_push_struct_blob_failed: %s\n",
ndr_errstr(ndr_err));
state->status = ndr_map_error2ntstatus(ndr_err);
goto done;
}
if (DEBUGLEVEL >= 10) {
DBG_DEBUG("\n");
NDR_PRINT_DEBUG(leases_db_value, value);
}
db_value = make_tdb_data(blob.data, blob.length);
state->status = dbwrap_record_store(rec, db_value, 0);
if (!NT_STATUS_IS_OK(state->status)) {
DBG_DEBUG("dbwrap_record_store returned %s\n",
nt_errstr(state->status));
}
done:
TALLOC_FREE(value);
}
static NTSTATUS leases_db_do_locked(
const struct GUID *client_guid,
const struct smb2_lease_key *lease_key,
void (*fn)(struct leases_db_value *value,
bool *modified,
void *private_data),
void *private_data)
{
struct leases_db_key_buf keybuf;
TDB_DATA db_key = leases_db_key(&keybuf, client_guid, lease_key);
struct leases_db_do_locked_state state = {
.fn = fn, .private_data = private_data,
};
NTSTATUS status;
if (!leases_db_init(false)) {
return NT_STATUS_INTERNAL_ERROR;
}
status = dbwrap_do_locked(
leases_db, db_key, leases_db_do_locked_fn, &state);
if (!NT_STATUS_IS_OK(status)) {
return status;
}
return state.status;
}
NTSTATUS leases_db_add(const struct GUID *client_guid,
const struct smb2_lease_key *lease_key,
const struct file_id *id,
@ -381,6 +489,40 @@ NTSTATUS leases_db_parse(const struct GUID *client_guid,
return state.status;
}
struct leases_db_rename_state {
const struct file_id *id;
const char *servicename_new;
const char *filename_new;
const char *stream_name_new;
NTSTATUS status;
};
static void leases_db_rename_fn(
struct leases_db_value *value, bool *modified, void *private_data)
{
struct leases_db_rename_state *state = private_data;
struct leases_db_file *file = NULL;
uint32_t i;
/* id must exist. */
for (i = 0; i < value->num_files; i++) {
if (file_id_equal(state->id, &value->files[i].id)) {
break;
}
}
if (i == value->num_files) {
state->status = NT_STATUS_NOT_FOUND;
return;
}
file = &value->files[i];
file->servicepath = state->servicename_new;
file->base_name = state->filename_new;
file->stream_name = state->stream_name_new;
*modified = true;
}
NTSTATUS leases_db_rename(const struct GUID *client_guid,
const struct smb2_lease_key *lease_key,
const struct file_id *id,
@ -388,21 +530,22 @@ NTSTATUS leases_db_rename(const struct GUID *client_guid,
const char *filename_new,
const char *stream_name_new)
{
struct leases_db_rename_state state = {
.id = id,
.servicename_new = servicename_new,
.filename_new = filename_new,
.stream_name_new = stream_name_new,
};
NTSTATUS status;
status = leases_db_del(client_guid,
lease_key,
id);
status = leases_db_do_locked(
client_guid, lease_key, leases_db_rename_fn, &state);
if (!NT_STATUS_IS_OK(status)) {
DBG_DEBUG("leases_db_do_locked failed: %s\n",
nt_errstr(status));
return status;
}
return leases_db_add(client_guid,
lease_key,
id,
servicename_new,
filename_new,
stream_name_new);
return state.status;
}
NTSTATUS leases_db_copy_file_ids(TALLOC_CTX *mem_ctx,