Commit Graph

29 Commits

Author SHA1 Message Date
Daniel P. Berrange b25e12daff qemu-nbd: add support for authorization of TLS clients
Currently any client which can complete the TLS handshake is able to use
the NBD server. The server admin can turn on the 'verify-peer' option
for the x509 creds to require the client to provide a x509 certificate.
This means the client will have to acquire a certificate from the CA
before they are permitted to use the NBD server. This is still a fairly
low bar to cross.

This adds a '--tls-authz OBJECT-ID' option to the qemu-nbd command which
takes the ID of a previously added 'QAuthZ' object instance. This will
be used to validate the client's x509 distinguished name. Clients
failing the authorization check will not be permitted to use the NBD
server.

For example to setup authorization that only allows connection from a client
whose x509 certificate distinguished name is

   CN=laptop.example.com,O=Example Org,L=London,ST=London,C=GB

escape the commas in the name and use:

  qemu-nbd --object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\
                    endpoint=server,verify-peer=yes \
           --object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,\
                     O=Example Org,,L=London,,ST=London,,C=GB' \
           --tls-creds tls0 \
           --tls-authz authz0 \
	   ....other qemu-nbd args...

NB: a real shell command line would not have leading whitespace after
the line continuation, it is just included here for clarity.

Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <20190227162035.18543-2-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: split long line in --help text, tweak 233 to show that whitespace
after ,, in identity= portion is actually okay]
Signed-off-by: Eric Blake <eblake@redhat.com>
2019-03-06 11:05:27 -06:00
Eric Blake 0ae2d54645 qemu-nbd: Deprecate qemu-nbd --partition
The existing qemu-nbd --partition code claims to handle logical
partitions up to 8, since its introduction in 2008 (commit 7a5ca86).
However, the implementation is bogus (actual MBR logical partitions
form a sort of linked list, with one partition per extended table
entry, rather than four logical partitions in a single extended
table), making the code unlikely to work for anything beyond -P5 on
actual guest images. What's more, the code does not support GPT
partitions, which are becoming more popular, and maintaining device
subsetting in both NBD and the raw device is unnecessary duplication
of effort (even if it is not too difficult).

Note that obtaining the offsets of a partition (MBR or GPT) can be
learned by using 'qemu-nbd -c /dev/nbd0 file.qcow2 && sfdisk --dump
/dev/nbd0', but by the time you've done that, you might as well
just mount /dev/nbd0p1 that the kernel creates for you instead of
bothering with qemu exporting a subset.  Or, keeping to just
user-space code, use nbdkit's partition filter, which has already
known both GPT and primary MBR partitions for a while, and was
just recently enhanced to support arbitrary logical MBR parititions.

Start the clock on the deprecation cycle, with examples of how
to accomplish device subsetting without using -P.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190125234837.2272-1-eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
2019-02-04 15:11:27 -06:00
Eric Blake 68b96f1583 qemu-nbd: Add --list option
We want to be able to detect whether a given qemu NBD server is
exposing the right export(s) and dirty bitmaps, at least for
regression testing.  We could use 'nbd-client -l' from the upstream
NBD project to list exports, but it's annoying to rely on
out-of-tree binaries; furthermore, nbd-client doesn't necessarily
know about all of the qemu NBD extensions.  Thus, it is time to add
a new mode to qemu-nbd that merely sniffs all possible information
from the server during handshake phase, then disconnects and dumps
the information.

This patch actually implements --list/-L, while reusing other
options such as --tls-creds for now designating how to connect
as the client (rather than their non-list usage of how to operate
as the server).

I debated about adding this functionality to something akin to
'qemu-img info' - but that tool does not readily lend itself
to connecting to an arbitrary NBD server without also tying to
a specific export (I may, however, still add ImageInfoSpecificNBD
for reporting the bitmaps available when connecting to a single
export).  And, while it may feel a bit odd that normally
qemu-nbd is a server but 'qemu-nbd -L' is a client, we are not
really making the qemu-nbd binary that much larger, because
'qemu-nbd -c' has to operate as both server and client
simultaneously across two threads when feeding the kernel module
for /dev/nbdN access.

Sample output:
$ qemu-nbd -L
exports available: 1
 export: ''
  size:  65536
  flags: 0x4ed ( flush fua trim zeroes df cache )
  min block: 512
  opt block: 4096
  max block: 33554432
  available meta contexts: 1
   base:allocation

Note that the output only lists sizes if the server sent
NBD_FLAG_HAS_FLAGS, because a newstyle server does not give
the size otherwise.  It has the side effect that for really
old servers that did not send any flags, the size is not
output even though it was available.  However, I'm not too
concerned about that - oldstyle servers are (rightfully)
getting less common to encounter (qemu 3.0 was the last
version where we even serve it), and most existing servers
that still even offer oldstyle negotiation (such as nbdkit)
still send flags (since that was added to the NBD protocol
in 2007 to permit read-only connections).

Not done here, but maybe worth future experiments: capture
the meat of NBDExportInfo into a QAPI struct, and use the
generated QAPI pretty-printers instead of hand-rolling our
output loop.  It would also permit us to add a JSON output
mode for machine parsing.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Message-Id: <20190117193658.16413-20-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2019-01-21 15:49:52 -06:00
Eric Blake 86b7f6771f qemu-nbd: Enhance man page
Document some useful qemu-nbd command lines. Mention some restrictions
on particular options, like -p being only for MBR images, or -c/-d
being Linux-only.  Update some text given the recent change to no
longer serve oldstyle protocol (missed in commit 7f7dfe2a).  Also,
consistently use trailing '.' in describing options.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Message-Id: <20190117193658.16413-4-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2019-01-21 15:49:51 -06:00
Eric Blake 636192c4b6 qemu-nbd: Add --bitmap=NAME option
Having to fire up qemu, then use QMP commands for nbd-server-start
and nbd-server-add, just to expose a persistent dirty bitmap, is
rather tedious.  Make it possible to expose a dirty bitmap using
just qemu-nbd (of course, for now this only works when qemu-nbd is
visiting a BDS formatted as qcow2).

Of course, any good feature also needs unit testing, so expand
iotest 223 to cover it.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190111194720.15671-9-eblake@redhat.com>
2019-01-14 10:09:46 -06:00
Eric Blake b1a75b3348 nbd: Add qemu-nbd -D for human-readable description
The NBD protocol allows servers to advertise a human-readable
description alongside an export name during NBD_OPT_LIST.  Add
an option to pass through the user's string to the NBD client.

Doing this also makes it easier to test commit 200650d4, which
is the client counterpart of receiving the description.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-2-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02 09:28:55 +01:00
Max Reitz ffb31e1da7 qemu-nbd: Add --fork option
Using the --fork option, one can make qemu-nbd fork the worker process.
The original process will exit on error of the worker or once the worker
enters the main loop.

Suggested-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-10-24 17:54:03 +02:00
Denis V. Lunev 39ca463e81 trace: enable tracing in qemu-nbd
Please note, trace_init_backends() must be called in the final process,
i.e. after daemonization. This is necessary to keep tracing thread in
the proper process.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1466174654-30130-6-git-send-email-den@openvz.org
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-06-28 21:14:12 +01:00
Daniel P. Berrange 77c9aaefd7 qemu-nbd: allow specifying image as a set of options args
Currently qemu-nbd allows an image filename to be passed on the
command line, but unless using the JSON format, it does not have
a way to set any options except the format eg

   qemu-nbd https://127.0.0.1/images/centos7.iso
   qemu-nbd /home/berrange/demo.qcow2

This adds a --image-opts arg that indicates that the positional
filename should be interpreted as a full option string, not
just a filename.

   qemu-nbd --image-opts driver=https,url=https://127.0.0.1/images,sslverify=off
   qemu-nbd --image-opts driver=file,filename=/home/berrange/demo.qcow2

This flag is mutually exclusive with the '-f' flag.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 09:50:04 +01:00
Daniel P. Berrange 145614a112 nbd: enable use of TLS with qemu-nbd server
This modifies the qemu-nbd program so that it is possible to
request the use of TLS with the server. It simply adds a new
command line option --tls-creds which is used to provide the
ID of a QCryptoTLSCreds object previously created via the
--object command line option.

For example

  qemu-nbd --object tls-creds-x509,id=tls0,endpoint=server,\
                    dir=/home/berrange/security/qemutls \
           --tls-creds tls0 \
           --exportname default

TLS requires the new style NBD protocol, so if no export name
is set (via --export-name), then we use the default NBD protocol
export name ""

TLS is only supported when using an IPv4/IPv6 socket listener.
It is not possible to use with UNIX sockets, which includes
when connecting the NBD server to a host device.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1455129674-17255-16-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-16 17:17:42 +01:00
Daniel P. Berrange 3d4b2f9c94 nbd: allow setting of an export name for qemu-nbd server
The qemu-nbd server currently always uses the old style protocol
since it never sets any export name. This is a problem because
future TLS support will require use of the new style protocol
negotiation.

This adds "--exportname NAME" / "-x NAME" arguments to qemu-nbd
which allow the user to set an explicit export name. When an
export name is set the server will always use the new style
NBD protocol.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1455129674-17255-11-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-16 17:16:00 +01:00
Daniel P. Berrange 0ab3b3375b qemu-nbd: add support for --object command line arg
Allow creation of user creatable object types with qemu-nbd
via a new --object command line arg. This will be used to supply
passwords and/or encryption keys to the various block driver
backends via the recently added 'secret' object type.

 # printf letmein > mypasswd.txt
 # qemu-nbd --object secret,id=sec0,file=mypasswd.txt \
      ...other nbd args...

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1455129674-17255-3-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-16 17:13:06 +01:00
Sitsofe Wheeler 5090121845 qemu-nbd: Fix texi sentence capitalisation
Capitalise the first letter of sentences (and reword for grammar) the
options section of qemu-nbd.texi.

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Message-Id: <1451979212-25479-4-git-send-email-sitsofe@yahoo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-09 15:45:26 +01:00
Sitsofe Wheeler 7e8911bb40 qemu-nbd: Minor texi updates
- Change some spacing.
- Add disconnect usage to synopsis.
- Highlight the command and its options in the synopsis.
- Fix up the grammar in the description.
- Move filename variable description out of the option table.
- Add a description of the dev variable.
- Remove duplicate entry for --format.
- Reword --discard documentation.
- Add --detect-zeroes documentation.
- Add reference to qemu man page to see also section.

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Message-Id: <1451979212-25479-3-git-send-email-sitsofe@yahoo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-09 15:45:26 +01:00
Sitsofe Wheeler b9dbb61757 qemu-nbd: Fix unintended texi verbatim formatting
Indented lines in the texi meant the perlpod produced interpreted the
paragraph as being verbatim (thus formatting codes were not
interpreted). Fix this by un-indenting problem lines.

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Message-Id: <1451979212-25479-2-git-send-email-sitsofe@yahoo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-09 15:45:26 +01:00
Hani Benhabiles 5672ee54d5 nbd: Miscellaneous typo fixes.
Signed-off-by: Hani Benhabiles <hani@linux.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2014-05-24 00:07:29 +04:00
Wenchao Xia 4323fdcf94 qemu-nbd: add doc for option -f
Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-04 15:19:00 +01:00
Wenchao Xia 8c116b0e41 qemu-nbd: support internal snapshot export
Now it is possible to directly export an internal snapshot, which
can be used to probe the snapshot's contents without qemu-img
convert.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-04 15:19:00 +01:00
Daniel P. Berrange e6b636779b Add -f FMT / --format FMT arg to qemu-nbd
Currently the qemu-nbd program will auto-detect the format of
any disk it is given. This behaviour is known to be insecure.
For example, if qemu-nbd initially exposes a 'raw' file to an
unprivileged app, and that app runs

   'qemu-img create -f qcow2 -o backing_file=/etc/shadow /dev/nbd0'

then the next time the app is started, the qemu-nbd will now
detect it as a 'qcow2' file and expose /etc/shadow to the
unprivileged app.

The only way to avoid this is to explicitly tell qemu-nbd what
disk format to use on the command line, completely disabling
auto-detection. This patch adds a '-f' / '--format' arg for
this purpose, mirroring what is already available via qemu-img
and qemu commands.

  qemu-nbd --format raw -p 9000 evil.img

will now always use raw, regardless of what format 'evil.img'
looks like it contains

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
[Use errx, not err. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-04-15 14:29:20 -05:00
Paolo Bonzini ded9d2d5e2 qemu-nbd: add --discard option
Similar to --cache and --aio, this option mimics the discard suboption
of "-drive".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-02-22 21:29:43 +01:00
Paolo Bonzini 0eb256a217 qemu-nbd: document --cache and --aio options
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-02-08 11:14:19 -06:00
Stefan Weil 071c939458 Replace Qemu by QEMU in user visible documentation
The official spelling is QEMU.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-04-07 13:58:06 +00:00
Ryota Ozaki bba7be962e qemu-nbd: Fix wrong description in qemu-nbd.texi
-c option needs argument <dev> but it's missing now.
This patch fixes it.

Signed-off-by: Ryota Ozaki <ozaki.ryota@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
2010-03-06 23:03:50 +01:00
aliguori 4a6b819c09 Fix formatting of documentation (Stefan Weil)
Fix formatting for documentation of nbd command line options.

Signed-off-by: Stefan Weil <weil@mail.berlios.de> 
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5301 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-22 20:41:57 +00:00
ths 75818250ba Allow QEMU to connect directly to an NBD server, by Laurent Vivier.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4838 c046a42c-6fe2-441c-8c8c-71466251a162
2008-07-03 13:41:03 +00:00
ths 3b05a8e91b Allow to share a disk image via nbd, by Laurent Vivier.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4837 c046a42c-6fe2-441c-8c8c-71466251a162
2008-07-03 12:45:02 +00:00
ths 2f7264888a Add a parameter to disable host cache, by Laurent Vivier.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4836 c046a42c-6fe2-441c-8c8c-71466251a162
2008-07-03 11:47:46 +00:00
ths cd831bd787 Merge NBD client/server, by Laurent Vivier.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4834 c046a42c-6fe2-441c-8c8c-71466251a162
2008-07-03 10:23:51 +00:00
bellard 7a5ca8648b qemu-nbd tool (Anthony Liguori)
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4596 c046a42c-6fe2-441c-8c8c-71466251a162
2008-05-27 21:13:40 +00:00