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nbd/server: Refactor handling of command sanity checks

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Upcoming additions to support NBD 64-bit effect lengths will add a new
command flag NBD_CMD_FLAG_PAYLOAD_LEN that needs to be considered in
our sanity checks of the client's messages (that is, more than just
CMD_WRITE have the potential to carry a client payload when extended
headers are in effect).  But before we can start to support that, it
is easier to first refactor the existing set of various if statements
over open-coded combinations of request->type to instead be a single
switch statement over all command types that sets witnesses, then
straight-line processing based on the witnesses.  No semantic change
is intended.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230829175826.377251-24-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
This commit is contained in:
Eric Blake 2023-08-29 12:58:32 -05:00
parent b257845932
commit 8db7e2d657
1 changed files with 75 additions and 45 deletions
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120
nbd/server.c
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@ -2317,11 +2317,16 @@ static int coroutine_fn nbd_co_send_bitmap(NBDClient *client,
* to the client (although the caller may still need to disconnect after
* reporting the error).
*/
static int coroutine_fn nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
static int coroutine_fn nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request,
Error **errp)
{
NBDClient *client = req->client;
int valid_flags;
bool check_length = false;
bool check_rofs = false;
bool allocate_buffer = false;
unsigned payload_len = 0;
int valid_flags = NBD_CMD_FLAG_FUA;
int ret;
g_assert(qemu_in_coroutine());
@ -2333,55 +2338,88 @@ static int coroutine_fn nbd_co_receive_request(NBDRequestData *req, NBDRequest *
trace_nbd_co_receive_request_decode_type(request->cookie, request->type,
nbd_cmd_lookup(request->type));
if (request->type != NBD_CMD_WRITE) {
/* No payload, we are ready to read the next request. */
req->complete = true;
}
if (request->type == NBD_CMD_DISC) {
switch (request->type) {
case NBD_CMD_DISC:
/* Special case: we're going to disconnect without a reply,
* whether or not flags, from, or len are bogus */
req->complete = true;
return -EIO;
case NBD_CMD_READ:
if (client->mode >= NBD_MODE_STRUCTURED) {
valid_flags |= NBD_CMD_FLAG_DF;
}
check_length = true;
allocate_buffer = true;
break;
case NBD_CMD_WRITE:
payload_len = request->len;
check_length = true;
allocate_buffer = true;
check_rofs = true;
break;
case NBD_CMD_FLUSH:
break;
case NBD_CMD_TRIM:
check_rofs = true;
break;
case NBD_CMD_CACHE:
check_length = true;
break;
case NBD_CMD_WRITE_ZEROES:
valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
check_rofs = true;
break;
case NBD_CMD_BLOCK_STATUS:
valid_flags |= NBD_CMD_FLAG_REQ_ONE;
break;
default:
/* Unrecognized, will fail later */
;
}
if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE ||
request->type == NBD_CMD_CACHE)
{
if (request->len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "len (%" PRIu64 ") is larger than max len (%u)",
request->len, NBD_MAX_BUFFER_SIZE);
return -EINVAL;
}
if (request->type != NBD_CMD_CACHE) {
req->data = blk_try_blockalign(client->exp->common.blk,
request->len);
if (req->data == NULL) {
error_setg(errp, "No memory");
return -ENOMEM;
}
/* Payload and buffer handling. */
if (!payload_len) {
req->complete = true;
}
if (check_length && request->len > NBD_MAX_BUFFER_SIZE) {
/* READ, WRITE, CACHE */
error_setg(errp, "len (%" PRIu64 ") is larger than max len (%u)",
request->len, NBD_MAX_BUFFER_SIZE);
return -EINVAL;
}
if (allocate_buffer) {
/* READ, WRITE */
req->data = blk_try_blockalign(client->exp->common.blk,
request->len);
if (req->data == NULL) {
error_setg(errp, "No memory");
return -ENOMEM;
}
}
if (request->type == NBD_CMD_WRITE) {
assert(request->len <= NBD_MAX_BUFFER_SIZE);
if (nbd_read(client->ioc, req->data, request->len, "CMD_WRITE data",
errp) < 0)
{
if (payload_len) {
/* WRITE */
assert(req->data);
ret = nbd_read(client->ioc, req->data, payload_len,
"CMD_WRITE data", errp);
if (ret < 0) {
return -EIO;
}
req->complete = true;
trace_nbd_co_receive_request_payload_received(request->cookie,
request->len);
payload_len);
}
/* Sanity checks. */
if (client->exp->nbdflags & NBD_FLAG_READ_ONLY &&
(request->type == NBD_CMD_WRITE ||
request->type == NBD_CMD_WRITE_ZEROES ||
request->type == NBD_CMD_TRIM)) {
if (client->exp->nbdflags & NBD_FLAG_READ_ONLY && check_rofs) {
/* WRITE, TRIM, WRITE_ZEROES */
error_setg(errp, "Export is read-only");
return -EROFS;
}
@ -2404,14 +2442,6 @@ static int coroutine_fn nbd_co_receive_request(NBDRequestData *req, NBDRequest *
request->len,
client->check_align);
}
valid_flags = NBD_CMD_FLAG_FUA;
if (request->type == NBD_CMD_READ && client->mode >= NBD_MODE_STRUCTURED) {
valid_flags |= NBD_CMD_FLAG_DF;
} else if (request->type == NBD_CMD_WRITE_ZEROES) {
valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
} else if (request->type == NBD_CMD_BLOCK_STATUS) {
valid_flags |= NBD_CMD_FLAG_REQ_ONE;
}
if (request->flags & ~valid_flags) {
error_setg(errp, "unsupported flags for command %s (got 0x%x)",
nbd_cmd_lookup(request->type), request->flags);