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[Qemu-block] [PULL 19/19] nbd: Don't kill server on client that doesn't
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 19/19] nbd: Don't kill server on client that doesn't request TLS |
Date: |
Fri, 15 Apr 2016 19:02:22 +0200 |
From: Eric Blake <address@hidden>
Upstream NBD documents (as of commit 4feebc95) that servers MAY
choose to operate in a conditional mode, where it is up to the
client whether to use TLS. For qemu's case, we want to always be
in FORCEDTLS mode, because of the risk of man-in-the-middle
attacks, and since we never export more than one device; likewise,
the qemu client will ALWAYS send NBD_OPT_STARTTLS as its first
option. But now that SELECTIVETLS servers exist, it is feasible
to encounter a (non-qemu) client that is programmed to talk to
such a server, and does not do NBD_OPT_STARTTLS first, but rather
wants to probe if it can use a non-encrypted export.
The NBD protocol documents that we should let such a client
continue trying, on the grounds that maybe the client will get the
hint to send NBD_OPT_STARTTLS, rather than immediately dropping
the connection.
Note that NBD_OPT_EXPORT_NAME is a special case: since it is the
only option request that can't have an error return, we have to
(continue to) drop the connection on that one; rather, what we are
fixing here is that all other replies prior to TLS initiation tell
the client NBD_REP_ERR_TLS_REQD, but keep the connection alive.
Signed-off-by: Eric Blake <address@hidden>
Message-id: address@hidden
Signed-off-by: Max Reitz <address@hidden>
---
nbd/server.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index 2a4dd10..a13a691 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -449,11 +449,19 @@ static int nbd_negotiate_options(NBDClient *client)
client->ioc = QIO_CHANNEL(tioc);
break;
+ case NBD_OPT_EXPORT_NAME:
+ /* No way to return an error to client, so drop connection */
+ TRACE("Option 0x%x not permitted before TLS", clientflags);
+ return -EINVAL;
+
default:
TRACE("Option 0x%x not permitted before TLS", clientflags);
+ if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
+ return -EIO;
+ }
nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_TLS_REQD,
clientflags);
- return -EINVAL;
+ break;
}
} else if (fixedNewstyle) {
switch (clientflags) {
@@ -471,6 +479,9 @@ static int nbd_negotiate_options(NBDClient *client)
return nbd_negotiate_handle_export_name(client, length);
case NBD_OPT_STARTTLS:
+ if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
+ return -EIO;
+ }
if (client->tlscreds) {
TRACE("TLS already enabled");
nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_INVALID,
@@ -480,7 +491,7 @@ static int nbd_negotiate_options(NBDClient *client)
nbd_negotiate_send_rep(client->ioc, NBD_REP_ERR_POLICY,
clientflags);
}
- return -EINVAL;
+ break;
default:
TRACE("Unsupported option 0x%x", clientflags);
if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
--
1.8.3.1
- [Qemu-block] [PULL 10/19] block: Don't ignore flags in blk_{, co, aio}_write_zeroes(), (continued)
- [Qemu-block] [PULL 10/19] block: Don't ignore flags in blk_{, co, aio}_write_zeroes(), Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 13/19] qemu-iotests: common.rc: drop unused _do(), Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 07/19] block/vpc: make checks on max table size a bit more lax, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 09/19] block/vpc: update comments to be compliant w/coding guidelines, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 11/19] Fix pflash migration, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 17/19] nbd: Don't fail handshake on NBD_OPT_LIST descriptions, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 16/19] qemu-iotests: 041: More robust assertion on quorum node, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 15/19] qemu-iotests: place valgrind log file in scratch dir, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 12/19] qemu-iotests: drop unused _within_tolerance() filter, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 18/19] nbd: fix assert() on qemu-nbd stop, Kevin Wolf, 2016/04/15
- [Qemu-block] [PULL 19/19] nbd: Don't kill server on client that doesn't request TLS,
Kevin Wolf <=
- [Qemu-block] [PULL 14/19] qemu-iotests: tests: do not set unused tmp variable, Kevin Wolf, 2016/04/15
- Re: [Qemu-block] [Qemu-devel] [PULL 00/19] Block layer patches for 2.6.0-rc3, Peter Maydell, 2016/04/18