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Re: [PATCH v3 11/14] nbd/client: Accept 64-bit block status chunks
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From: |
Vladimir Sementsov-Ogievskiy |
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Subject: |
Re: [PATCH v3 11/14] nbd/client: Accept 64-bit block status chunks |
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Date: |
Wed, 31 May 2023 20:00:43 +0300 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 |
On 15.05.23 22:53, Eric Blake wrote:
Because we use NBD_CMD_FLAG_REQ_ONE with NBD_CMD_BLOCK_STATUS, a
client in narrow mode should not be able to provoke a server into
sending a block status result larger than the client's 32-bit request.
But in extended mode, a 64-bit status request must be able to handle a
64-bit status result, once a future patch enables the client
requesting extended mode. We can also tolerate a non-compliant server
sending the new chunk even when it should not.
In normal execution, we are only requesting "base:allocation" which
never exceeds 32 bits. But during testing with x-dirty-bitmap, we can
force qemu to connect to some other context that might have 64-bit
status bit; however, we ignore those upper bits (other than mapping
qemu:allocation-depth into something that 'qemu-img map --output=json'
can expose), and since it is only testing, we really don't bother with
checking whether more than the two least-significant bits are set.
Signed-off-by: Eric Blake <eblake@redhat.com>
---
block/nbd.c | 39 ++++++++++++++++++++++++++++-----------
block/trace-events | 1 +
2 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/block/nbd.c b/block/nbd.c
index d6caea44928..150dfe7170c 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -610,13 +610,16 @@ static int nbd_parse_offset_hole_payload(BDRVNBDState *s,
*/
static int nbd_parse_blockstatus_payload(BDRVNBDState *s,
NBDStructuredReplyChunk *chunk,
- uint8_t *payload, uint64_t
orig_length,
- NBDExtent *extent, Error **errp)
+ uint8_t *payload, bool wide,
+ uint64_t orig_length,
+ NBDExtentExt *extent, Error **errp)
{
uint32_t context_id;
+ uint32_t count = 0;
+ size_t len = wide ? sizeof(*extent) : sizeof(NBDExtent);
/* The server succeeded, so it must have sent [at least] one extent */
- if (chunk->length < sizeof(context_id) + sizeof(*extent)) {
+ if (chunk->length < sizeof(context_id) + wide * sizeof(count) + len) {
error_setg(errp, "Protocol error: invalid payload for "
"NBD_REPLY_TYPE_BLOCK_STATUS");
return -EINVAL;
@@ -631,8 +634,14 @@ static int nbd_parse_blockstatus_payload(BDRVNBDState *s,
return -EINVAL;
}
- extent->length = payload_advance32(&payload);
- extent->flags = payload_advance32(&payload);
+ if (wide) {
+ count = payload_advance32(&payload);
+ extent->length = payload_advance64(&payload);
+ extent->flags = payload_advance64(&payload);
+ } else {
+ extent->length = payload_advance32(&payload);
+ extent->flags = payload_advance32(&payload);
+ }
if (extent->length == 0) {
error_setg(errp, "Protocol error: server sent status chunk with "
@@ -672,7 +681,8 @@ static int nbd_parse_blockstatus_payload(BDRVNBDState *s,
* connection; just ignore trailing extents, and clamp things to
* the length of our request.
*/
- if (chunk->length > sizeof(context_id) + sizeof(*extent)) {
+ if (count != wide ||
hard to read for me. Could it be simply "count > 1 ||" ?
+ chunk->length > sizeof(context_id) + wide * sizeof(count) + len) {
trace_nbd_parse_blockstatus_compliance("more than one extent");
}
if (extent->length > orig_length) {
@@ -1117,7 +1127,7 @@ static int coroutine_fn
nbd_co_receive_cmdread_reply(BDRVNBDState *s, uint64_t h
static int coroutine_fn nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
uint64_t handle,
uint64_t length,
- NBDExtent *extent,
+ NBDExtentExt *extent,
int *request_ret,
Error **errp)
{
NBDReplyChunkIter iter;
@@ -1125,6 +1135,7 @@ static int coroutine_fn
nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
void *payload = NULL;
Error *local_err = NULL;
bool received = false;
+ bool wide = false;
assert(!extent->length);
NBD_FOREACH_REPLY_CHUNK(s, iter, handle, false, NULL, &reply, &payload) {
@@ -1134,7 +1145,13 @@ static int coroutine_fn
nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
assert(nbd_reply_is_structured(&reply));
switch (chunk->type) {
+ case NBD_REPLY_TYPE_BLOCK_STATUS_EXT:
+ wide = true;
+ /* fallthrough */
case NBD_REPLY_TYPE_BLOCK_STATUS:
+ if (s->info.extended_headers != wide) {
+ trace_nbd_extended_headers_compliance("block_status");
You set wide to true once, on first "NBD_REPLY_TYPE_BLOCK_STATUS_EXT", and then parse
following "NBD_REPLY_TYPE_BLOCK_STATUS" if the come with wide=true.
Should it be:
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -1135,7 +1135,7 @@ static int coroutine_fn
nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
void *payload = NULL;
Error *local_err = NULL;
bool received = false;
- bool wide = false;
+ bool wide;
assert(!extent->length);
NBD_FOREACH_REPLY_CHUNK(s, iter, handle, false, NULL, &reply, &payload) {
@@ -1146,9 +1146,8 @@ static int coroutine_fn
nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
switch (chunk->type) {
case NBD_REPLY_TYPE_BLOCK_STATUS_EXT:
- wide = true;
- /* fallthrough */
case NBD_REPLY_TYPE_BLOCK_STATUS:
+ wide = chunk->type == NBD_REPLY_TYPE_BLOCK_STATUS_EXT;
if (s->info.extended_headers != wide) {
trace_nbd_extended_headers_compliance("block_status");
}
+ }
if (received) {
nbd_channel_error(s, -EINVAL);
error_setg(&local_err, "Several BLOCK_STATUS chunks in
reply");
@@ -1142,9 +1159,9 @@ static int coroutine_fn
nbd_co_receive_blockstatus_reply(BDRVNBDState *s,
}
received = true;
- ret = nbd_parse_blockstatus_payload(s, &reply.structured,
- payload, length, extent,
- &local_err);
+ ret = nbd_parse_blockstatus_payload(
+ s, &reply.structured, payload, wide,
+ length, extent, &local_err);
if (ret < 0) {
nbd_channel_error(s, ret);
nbd_iter_channel_error(&iter, ret, &local_err);
@@ -1374,7 +1391,7 @@ static int coroutine_fn GRAPH_RDLOCK
nbd_client_co_block_status(
int64_t *pnum, int64_t *map, BlockDriverState **file)
{
int ret, request_ret;
- NBDExtent extent = { 0 };
+ NBDExtentExt extent = { 0 };
BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
Error *local_err = NULL;
diff --git a/block/trace-events b/block/trace-events
index 48dbf10c66f..afb32fcce5b 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -168,6 +168,7 @@ iscsi_xcopy(void *src_lun, uint64_t src_off, void *dst_lun,
uint64_t dst_off, ui
# nbd.c
nbd_parse_blockstatus_compliance(const char *err) "ignoring extra data from
non-compliant server: %s"
nbd_structured_read_compliance(const char *type) "server sent non-compliant
unaligned read %s chunk"
+nbd_extended_headers_compliance(const char *type) "server sent non-compliant %s
chunk not matching choice of extended headers"
nbd_read_reply_entry_fail(int ret, const char *err) "ret = %d, err: %s"
nbd_co_request_fail(uint64_t from, uint32_t len, uint64_t handle, uint16_t flags, uint16_t type, const char *name, int ret, const char
*err) "Request failed { .from = %" PRIu64", .len = %" PRIu32 ", .handle = %" PRIu64 ", .flags =
0x%" PRIx16 ", .type = %" PRIu16 " (%s) } ret = %d, err: %s"
nbd_client_handshake(const char *export_name) "export '%s'"
--
Best regards,
Vladimir