Eric Blake
2023-May-15 19:53 UTC
[Libguestfs] [PATCH v3 11/14] nbd/client: Accept 64-bit block status chunks
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 at 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 ||
+ 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");
+ }
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'"
--
2.40.1
Vladimir Sementsov-Ogievskiy
2023-May-31 17:00 UTC
[Libguestfs] [PATCH v3 11/14] nbd/client: Accept 64-bit block status chunks
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 at 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
Eric Blake
2023-May-31 17:40 UTC
[Libguestfs] [PATCH v3 11/14] nbd/client: Accept 64-bit block status chunks
On Wed, May 31, 2023 at 08:00:43PM +0300, Vladimir Sementsov-Ogievskiy wrote:> 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. > > > > @@ -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 ||" ?For existing commands (compact), count is initialized to 0 as it is not transferred over the wire. For extended commands, count is transferred over the wire, but we expect it to be 1 (and not 0). Comparing count != wide is more precise than checking count > 0 (which should never happen for compact, but would be a bug for extended).> > > + 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) {Good observation, since we reach this multiple times in a loop. I'm squashing that in. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org