| Message ID | 20190401140903.19186-11-eblake@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [PULL,01/14] qemu-img: Report bdrv_block_status failures | expand |
On 4/1/19 9:08 AM, Eric Blake wrote: > The NBD spec suggests that a server should never advertise a size > inconsistent with its minimum block alignment, as that tail is > effectively inaccessible to a compliant client obeying those block > constraints. Since we have a habit of rounding up rather than > truncating, to avoid losing the last few bytes of user input, and we > cannot access the tail when the server advertises bogus block sizing, > abort the connection to alert the server to fix their bug. And > rejecting such servers matches what we already did for a min_block > that was not a power of 2 or which was larger than max_block. > > Does not impact either qemu (which always sends properly aligned > sizes) or nbdkit (which does not send minimum block requirements yet); > so this is mostly aimed at new NBD server implementations, and ensures > that the rest of our code can assume the size is aligned. > > Signed-off-by: Eric Blake <eblake@redhat.com> > Message-Id: <20190330155704.24191-1-eblake@redhat.com> > Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > --- > nbd/client.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/nbd/client.c b/nbd/client.c > index de7da48246b..427980bdd22 100644 > --- a/nbd/client.c > +++ b/nbd/client.c > @@ -426,6 +426,14 @@ static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt, > nbd_send_opt_abort(ioc); > return -1; > } > + if (info->min_block && > + !QEMU_IS_ALIGNED(info->size, info->min_block)) { > + error_setg(errp, "export size %" PRIu64 "is not multiple of " Missing a space in the error message. If I have any other patches worthy of an -rc3 pull request, I'll do the obvious fix then.
diff --git a/nbd/client.c b/nbd/client.c index de7da48246b..427980bdd22 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -426,6 +426,14 @@ static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt, nbd_send_opt_abort(ioc); return -1; } + if (info->min_block && + !QEMU_IS_ALIGNED(info->size, info->min_block)) { + error_setg(errp, "export size %" PRIu64 "is not multiple of " + "minimum block size %" PRIu32, info->size, + info->min_block); + nbd_send_opt_abort(ioc); + return -1; + } trace_nbd_receive_negotiate_size_flags(info->size, info->flags); break;