Commit Graph

30 Commits

Author SHA1 Message Date
Marc-André Lureau 9e6bdef224 util: add qemu_write_pidfile()
There are variants of qemu_create_pidfile() in qemu-pr-helper and
qemu-ga. Let's have a common implementation in libqemuutil.

The code is initially based from pr-helper write_pidfile(), with
various improvements and suggestions from Daniel Berrangé:

  QEMU will leave the pidfile existing on disk when it exits which
  initially made me think it avoids the deletion race. The app
  managing QEMU, however, may well delete the pidfile after it has
  seen QEMU exit, and even if the app locks the pidfile before
  deleting it, there is still a race.

  eg consider the following sequence

        QEMU 1        libvirtd        QEMU 2

  1.    lock(pidfile)

  2.    exit()

  3.                 open(pidfile)

  4.                 lock(pidfile)

  5.                                  open(pidfile)

  6.                 unlink(pidfile)

  7.                 close(pidfile)

  8.                                  lock(pidfile)

  IOW, at step 8 the new QEMU has successfully acquired the lock, but
  the pidfile no longer exists on disk because it was deleted after
  the original QEMU exited.

  While we could just say no external app should ever delete the
  pidfile, I don't think that is satisfactory as people don't read
  docs, and admins don't like stale pidfiles being left around on
  disk.

  To make this robust, I think we might want to copy libvirt's
  approach to pidfile acquisition which runs in a loop and checks that
  the file on disk /after/ acquiring the lock matches the file that
  was locked. Then we could in fact safely let QEMU delete its own
  pidfiles on clean exit..

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180831145314.14736-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-10-02 18:47:55 +02:00
Peter Xu 3ab72385b2 qapi: Drop qapi_event_send_FOO()'s Error ** argument
The generated qapi_event_send_FOO() take an Error ** argument.  They
can't actually fail, because all they do with the argument is passing it
to functions that can't fail: the QObject output visitor, and the
@qmp_emit callback, which is either monitor_qapi_event_queue() or
event_test_emit().

Drop the argument, and pass &error_abort to the QObject output visitor
and @qmp_emit instead.

Suggested-by: Eric Blake <eblake@redhat.com>
Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180815133747.25032-4-peterx@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message rewritten, update to qapi-code-gen.txt corrected]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2018-08-28 18:21:38 +02:00
Murilo Opsfelder Araujo 1b0578f5c4 qemu-pr-helper: Fix build on CentOS 7
After commit b3f1c8c413 "qemu-pr-helper: use new
libmultipath API", QEMU started using new libmultipath API, which is not
available on CentOS 7.x.

This fixes that by probing the new libmultipath API in configure.  If it fails,
then try probing the old API.  If it fails, then consider libmultipath not
available.

With this, configure script defines CONFIG_MPATH_NEW_API that is used in
scsi/qemu-pr-helper.c to use the new libmultipath API.

Fixes: b3f1c8c413
BugLink: https://bugs.launchpad.net/qemu/+bug/1786343
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Message-Id: <20180810141116.24016-1-muriloo@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-08-23 13:32:50 +02:00
Paolo Bonzini ea3d77c889 pr-manager-helper: fix memory leak on event
Reported by Coverity.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-07-06 18:39:19 +02:00
Michal Privoznik 2729d79d49 pr-helper: Rework socket path handling
When reviewing Paolo's pr-helper patches I've noticed couple of
problems:

1) socket_path needs to be calculated at two different places
(one for printing out help, the other if socket activation is NOT
used),

2) even though the default socket_path is allocated in
compute_default_paths() it is the only default path the function
handles. For instance, pidfile is allocated outside of this
function. And yet again, at different places than 1)

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <c791ba035f26ea957e8f3602e3009b621769b1ba.1530611283.git.mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-07-06 18:39:19 +02:00
Paolo Bonzini ee8c13b814 pr-helper: avoid error on PR IN command with zero request size
After reading a PR IN command with zero request size in prh_read_request,
the resp->result field will be uninitialized and the resp.sz field will
be also uninitialized when returning to prh_co_entry.

If resp->result == GOOD (from a previous successful reply or just luck),
then the assert in prh_write_response might not be triggered and
uninitialized response will be sent.

The fix is to remove the whole handling of sz == 0 in prh_co_entry.
Those errors apply only to PR OUT commands and it's perfectly okay to
catch them later in do_pr_out and multipath_pr_out; the check for
too-short parameters in fact doesn't apply in the easy SG_IO case, as
it can be left to the target firmware even.

The result is that prh_read_request does not fail requests anymore and
prh_co_entry becomes simpler.

Reported-by: Dima Stepanov <dimastep@yandex-team.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-07-06 18:39:19 +02:00
Paolo Bonzini e2c81a4510 pr-manager-helper: report event on connection/disconnection
Let management know if there were any problems communicating with
qemu-pr-helper.  The event is edge-triggered, and is sent every time
the connection status of the pr-manager-helper object changes.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-06-28 19:05:35 +02:00
Paolo Bonzini 5f64089416 pr-manager: add query-pr-managers QMP command
This command lets you query the connection status of each pr-manager-helper
object.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-06-28 19:05:35 +02:00
Paolo Bonzini 58b3017f7f pr-manager: put stubs in .c file
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-06-28 19:05:35 +02:00
Paolo Bonzini aad10040d4 pr-manager-helper: avoid SIGSEGV when writing to the socket fail
When writing to the qemu-pr-helper socket failed, the persistent
reservation manager was correctly disconnecting the socket, but it
did not clear pr_mgr->ioc.  So the rest of the code did not know
that the socket had been disconnected, accessed pr_mgr->ioc and
happily caused a crash.

To reproduce, it is enough to stop qemu-pr-helper between QEMU
startup and executing e.g. sg_persist -k /dev/sdb.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-06-28 19:05:35 +02:00
Paolo Bonzini 86933b4e78 pr-helper: fix assertion failure on failed multipath PERSISTENT RESERVE IN
The response size is expected to be zero if the SCSI status is not
"GOOD", but nothing was resetting it.

This can be reproduced simply by "sg_persist -s /dev/sdb" where /dev/sdb
in the guest is a scsi-block device corresponding to a multipath device
on the host.

Before:

  PR in (Read full status): Aborted command

and on the host:

  prh_write_response: Assertion `resp->sz == 0' failed.

After:

  PR in (Read full status): bad field in cdb or parameter list
  (perhaps unsupported service action)

Reported-by: Jiri Belka <jbelka@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
2018-06-28 19:05:35 +02:00
Paolo Bonzini 50fa332516 pr-helper: fix --socket-path default in help
Currently --help shows "(default '(null)')" for the -k/--socket-path
option.  Fix it by getting the default path in /var/run.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
2018-06-28 19:05:34 +02:00
Michal Privoznik bd6b1c8324 qemu-pr-helper: Write pidfile more often
Let's write pidfile even if user did not request --daemon but
they requested just --pidfile. Libvirt will use exactly this.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-04-09 16:36:40 +02:00
Michal Privoznik 8dc0bf2647 qemu-pr-helper: Daemonize before dropping privileges
After we've dropped privileges it might be not possible to write
pidfile. For instance, if this binary is run as root (because
user wants it to write pidfile to some privileged location)
writing pidfile fails because privileges are dropped before we
even get to that.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-04-09 16:36:40 +02:00
Michal Privoznik f8e1a98964 qemu-pr-helper: Actually allow users to specify pidfile
Due to wrong specification of arguments to getopt_long() any
attempt to set pidfile resulted in:

1) the default to be leaked
2) the @pidfile variable to be set to NULL (because optarg is
NULL without this patch).

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <6f10cd53d361a395aa0e85a9311ec4e9a8fc11e5.1521868451.git.mprivozn@redhat.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-03-26 14:37:15 +02:00
Thomas Huth 7e563bfb8a Polish the version strings containing the package version
Since commit 67a1de0d19 there is no space anymore between the
version number and the parentheses when running configure with
--with-pkgversion=foo :

 $ qemu-system-s390x --version
 QEMU emulator version 2.11.50(foo)

But the space is included when building without that option
when building from a git checkout:

 $ qemu-system-s390x --version
 QEMU emulator version 2.11.50 (v2.11.0-1494-gbec9c64-dirty)

The same confusion exists with the "query-version" QMP command.
Let's fix this by introducing a proper QEMU_FULL_VERSION definition
that includes the space and parentheses, while the QEMU_PKGVERSION
should just cleanly contain the package version string itself.
Note that this also changes the behavior of the "query-version" QMP
command (the space and parentheses are not included there anymore),
but that's supposed to be OK since the strings there are not meant
to be parsed by other tools.

Fixes: 67a1de0d19
Buglink: https://bugs.launchpad.net/qemu/+bug/1673373
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1518692807-25859-1-git-send-email-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-03-12 16:12:47 +01:00
Markus Armbruster 8f0a3716e4 Clean up includes
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes, with the change
to target/s390x/gen-features.c manually reverted, and blank lines
around deletions collapsed.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180201111846.21846-3-armbru@redhat.com>
2018-02-09 05:05:11 +01:00
Paolo Bonzini 2770c90d43 scsi: fix scsi_convert_sense crash when in_buf == NULL && in_len == 0
scsi_disk_emulate_command passes in_buf == NULL when sent a REQUEST
SENSE command.  Check for in_len == 0 before dereferencing in_buf.

Fixes: f68d98b21f
Reported-by: Roman Kagan <rkagan@virtuozzo.com>
Tested-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-01-12 09:54:13 +01:00
Paolo Bonzini 9661e208f8 scsi: replace hex constants with #defines
Sense keys have nice #defines in scsi/constants.h, use them.

Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-12-21 09:30:32 +01:00
Paolo Bonzini f68d98b21f scsi: provide general-purpose functions to manage sense data
Extract the common parts of scsi_sense_buf_to_errno, scsi_convert_sense
and scsi_target_send_command's REQUEST SENSE handling into two new
functions scsi_parse_sense_buf and scsi_build_sense_buf.

Fix a bug in scsi_target_send_command along the way; the length was
written in buf[10] rather than buf[7].

Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Fixes: b07fbce634 ("scsi-bus: correct responses for INQUIRY and REQUEST SENSE")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-12-21 09:30:32 +01:00
Paolo Bonzini a4a9b6eaf3 qemu-pr-helper: miscellaneous fixes
1) Return a generic sense if TEST UNIT READY does not provide one;

2) Fix two mistakes in copying from the spec.

Cc: qemu-stable@nongnu.org
Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-12-20 22:29:26 +01:00
Paolo Bonzini b3f1c8c413 qemu-pr-helper: use new libmultipath API
libmultipath has recently changed its API.  The new API supports multi-threaded
clients better.  Unfortunately there is no backwards-compatibility, so we just
switch to the new one.  Running QEMU compiled with the new library on the old
library will likely crash, while doing the opposite will cause QEMU not to
start at all (because udev, get_multipath_config and put_multipath_config
are undefined).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-10-18 10:15:09 +02:00
Paolo Bonzini 9bad2a6b9d scsi: add persistent reservation manager using qemu-pr-helper
This adds a concrete subclass of pr-manager that talks to qemu-pr-helper.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22 21:07:27 +02:00
Paolo Bonzini fe8fc5ae5c scsi: add multipath support to qemu-pr-helper
Proper support of persistent reservation for multipath devices requires
communication with the multipath daemon, so that the reservation is
registered and applied when a path comes up.  The device mapper
utilities provide a library to do so; this patch makes qemu-pr-helper.c
detect multipath devices and, when one is found, delegate the operation
to libmpathpersist.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22 21:07:27 +02:00
Paolo Bonzini b855f8d175 scsi: build qemu-pr-helper
Introduce a privileged helper to run persistent reservation commands.
This lets virtual machines send persistent reservations without using
CAP_SYS_RAWIO or out-of-tree patches.  The helper uses Unix permissions
and SCM_RIGHTS to restrict access to processes that can access its socket
and prove that they have an open file descriptor for a raw SCSI device.

The next patch will also correct the usage of persistent reservations
with multipath devices.

It would also be possible to support for Linux's IOC_PR_* ioctls in
the future, to support NVMe devices.  For now, however, only SCSI is
supported.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22 21:07:24 +02:00
Paolo Bonzini 7c9e527659 scsi, file-posix: add support for persistent reservation management
It is a common requirement for virtual machine to send persistent
reservations, but this currently requires either running QEMU with
CAP_SYS_RAWIO, or using out-of-tree patches that let an unprivileged
QEMU bypass Linux's filter on SG_IO commands.

As an alternative mechanism, the next patches will introduce a
privileged helper to run persistent reservation commands without
expanding QEMU's attack surface unnecessarily.

The helper is invoked through a "pr-manager" QOM object, to which
file-posix.c passes SG_IO requests for PERSISTENT RESERVE OUT and
PERSISTENT RESERVE IN commands.  For example:

  $ qemu-system-x86_64
      -device virtio-scsi \
      -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock
      -drive if=none,id=hd,driver=raw,file.filename=/dev/sdb,file.pr-manager=helper0
      -device scsi-block,drive=hd

or:

  $ qemu-system-x86_64
      -device virtio-scsi \
      -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock
      -blockdev node-name=hd,driver=raw,file.driver=host_device,file.filename=/dev/sdb,file.pr-manager=helper0
      -device scsi-block,drive=hd

Multiple pr-manager implementations are conceivable and possible, though
only one is implemented right now.  For example, a pr-manager could:

- talk directly to the multipath daemon from a privileged QEMU
  (i.e. QEMU links to libmpathpersist); this makes reservation work
  properly with multipath, but still requires CAP_SYS_RAWIO

- use the Linux IOC_PR_* ioctls (they require CAP_SYS_ADMIN though)

- more interestingly, implement reservations directly in QEMU
  through file system locks or a shared database (e.g. sqlite)

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22 01:06:51 +02:00
Paolo Bonzini 08e2c9f19c scsi: move block/scsi.h to include/scsi/constants.h
Complete the transition by renaming this header, which was
shared by block/iscsi.c and the SCSI emulation code.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19 14:09:31 +02:00
Paolo Bonzini 1ead6b4e24 scsi: introduce sg_io_sense_from_errno
Move more knowledge of SG_IO out of hw/scsi/scsi-generic.c, for
reusability.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19 14:09:11 +02:00
Paolo Bonzini a3760467c6 scsi: introduce scsi_build_sense
Move more knowledge of sense data format out of hw/scsi/scsi-bus.c
for reusability.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19 14:09:11 +02:00
Paolo Bonzini e5b5728cd3 scsi: move non-emulation specific code to scsi/
util/scsi.c includes some SCSI code that is shared by block/iscsi.c and
hw/scsi, but the introduction of the persistent reservation helper
will add many more instances of this.  There is also include/block/scsi.h,
which actually is not part of the core block layer.

The persistent reservation manager will also need a home.  A scsi/
directory provides one for both the aforementioned shared code and
the PR manager code.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19 14:09:11 +02:00