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  1. 15 1月, 2018 5 次提交
  3. 13 1月, 2018 1 次提交
    • P
      Merge remote-tracking branch 'remotes/kraxel/tags/vnc-20180112-pull-request' into staging · 7398166d
      由 Peter Maydell 提交于 
      vnc: limit memory usage (CVE-2017-15124)

# gpg: Signature made Fri 12 Jan 2018 12:57:22 GMT
# gpg:                using RSA key 0x4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/vnc-20180112-pull-request:
  ui: mix misleading comments & return types of VNC I/O helper methods
  ui: add trace events related to VNC client throttling
  ui: place a hard cap on VNC server output buffer size
  ui: fix VNC client throttling when forced update is requested
  ui: fix VNC client throttling when audio capture is active
  ui: refactor code for determining if an update should be sent to the client
  ui: correctly reset framebuffer update state after processing dirty regions
  ui: introduce enum to track VNC client framebuffer update request state
  ui: track how much decoded data we consumed when doing SASL encoding
  ui: avoid pointless VNC updates if framebuffer isn't dirty
  ui: remove redundant indentation in vnc_client_update
  ui: remove unreachable code in vnc_update_client
  ui: remove 'sync' parameter from vnc_update_client
  vnc: fix debug spelling
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
      7398166d
  5. 12 1月, 2018 17 次提交
    • P
      target/xtensa: Remove duplicate typedef of DisasContext · a3380cf6
      由 Peter Maydell 提交于 
      Some older versions of gcc complain if a typedef is defined twice:

target/xtensa/translate.c:81: error: redefinition of typedef 'DisasContext'
target/xtensa/cpu.h:339: note: previous declaration of 'DisasContext' was here

Remove the now-redundant typedef from the definition of the struct in
translate.c.
Reported-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1515762528-22818-1-git-send-email-peter.maydell@linaro.org
      a3380cf6
    • D
      ui: mix misleading comments & return types of VNC I/O helper methods · 30b80fd5
      由 Daniel P. Berrange 提交于 
      While the QIOChannel APIs for reading/writing data return ssize_t, with negative
value indicating an error, the VNC code passes this return value through the
vnc_client_io_error() method. This detects the error condition, disconnects the
client and returns 0 to indicate error. Thus all the VNC helper methods should
return size_t (unsigned), and misleading comments which refer to the possibility
of negative return values need fixing.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-14-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      30b80fd5
    • D
      ui: add trace events related to VNC client throttling · 6aa22a29
      由 Daniel P. Berrange 提交于 
      The VNC client throttling is quite subtle so will benefit from having trace
points available for live debugging.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-13-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      6aa22a29
    • D
      ui: place a hard cap on VNC server output buffer size · f887cf16
      由 Daniel P. Berrange 提交于 
      The previous patches fix problems with throttling of forced framebuffer updates
and audio data capture that would cause the QEMU output buffer size to grow
without bound. Those fixes are graceful in that once the client catches up with
reading data from the server, everything continues operating normally.

There is some data which the server sends to the client that is impractical to
throttle. Specifically there are various pseudo framebuffer update encodings to
inform the client of things like desktop resizes, pointer changes, audio
playback start/stop, LED state and so on. These generally only involve sending
a very small amount of data to the client, but a malicious guest might be able
to do things that trigger these changes at a very high rate. Throttling them is
not practical as missed or delayed events would cause broken behaviour for the
client.

This patch thus takes a more forceful approach of setting an absolute upper
bound on the amount of data we permit to be present in the output buffer at
any time. The previous patch set a threshold for throttling the output buffer
by allowing an amount of data equivalent to one complete framebuffer update and
one seconds worth of audio data. On top of this it allowed for one further
forced framebuffer update to be queued.

To be conservative, we thus take that throttling threshold and multiply it by
5 to form an absolute upper bound. If this bound is hit during vnc_write() we
forceably disconnect the client, refusing to queue further data. This limit is
high enough that it should never be hit unless a malicious client is trying to
exploit the sever, or the network is completely saturated preventing any sending
of data on the socket.

This completes the fix for CVE-2017-15124 started in the previous patches.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-12-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      f887cf16
    • D
      ui: fix VNC client throttling when forced update is requested · ada8d2e4
      由 Daniel P. Berrange 提交于 
      The VNC server must throttle data sent to the client to prevent the 'output'
buffer size growing without bound, if the client stops reading data off the
socket (either maliciously or due to stalled/slow network connection).

The current throttling is very crude because it simply checks whether the
output buffer offset is zero. This check is disabled if the client has requested
a forced update, because we want to send these as soon as possible.

As a result, the VNC client can cause QEMU to allocate arbitrary amounts of RAM.
They can first start something in the guest that triggers lots of framebuffer
updates eg play a youtube video. Then repeatedly send full framebuffer update
requests, but never read data back from the server. This can easily make QEMU's
VNC server send buffer consume 100MB of RAM per second, until the OOM killer
starts reaping processes (hopefully the rogue QEMU process, but it might pick
others...).

To address this we make the throttling more intelligent, so we can throttle
full updates. When we get a forced update request, we keep track of exactly how
much data we put on the output buffer. We will not process a subsequent forced
update request until this data has been fully sent on the wire. We always allow
one forced update request to be in flight, regardless of what data is queued
for incremental updates or audio data. The slight complication is that we do
not initially know how much data an update will send, as this is done in the
background by the VNC job thread. So we must track the fact that the job thread
has an update pending, and not process any further updates until this job is
has been completed & put data on the output buffer.

This unbounded memory growth affects all VNC server configurations supported by
QEMU, with no workaround possible. The mitigating factor is that it can only be
triggered by a client that has authenticated with the VNC server, and who is
able to trigger a large quantity of framebuffer updates or audio samples from
the guest OS. Mostly they'll just succeed in getting the OOM killer to kill
their own QEMU process, but its possible other processes can get taken out as
collateral damage.

This is a more general variant of the similar unbounded memory usage flaw in
the websockets server, that was previously assigned CVE-2017-15268, and fixed
in 2.11 by:

  commit a7b20a8e
  Author: Daniel P. Berrange <berrange@redhat.com>
  Date:   Mon Oct 9 14:43:42 2017 +0100

    io: monitor encoutput buffer size from websocket GSource

This new general memory usage flaw has been assigned CVE-2017-15124, and is
partially fixed by this patch.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-11-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      ada8d2e4
    • D
      ui: fix VNC client throttling when audio capture is active · e2b72cb6
      由 Daniel P. Berrange 提交于 
      The VNC server must throttle data sent to the client to prevent the 'output'
buffer size growing without bound, if the client stops reading data off the
socket (either maliciously or due to stalled/slow network connection).

The current throttling is very crude because it simply checks whether the
output buffer offset is zero. This check must be disabled if audio capture is
enabled, because when streaming audio the output buffer offset will rarely be
zero due to queued audio data, and so this would starve framebuffer updates.

As a result, the VNC client can cause QEMU to allocate arbitrary amounts of RAM.
They can first start something in the guest that triggers lots of framebuffer
updates eg play a youtube video. Then enable audio capture, and simply never
read data back from the server. This can easily make QEMU's VNC server send
buffer consume 100MB of RAM per second, until the OOM killer starts reaping
processes (hopefully the rogue QEMU process, but it might pick others...).

To address this we make the throttling more intelligent, so we can throttle
when audio capture is active too. To determine how to throttle incremental
updates or audio data, we calculate a size threshold. Normally the threshold is
the approximate number of bytes associated with a single complete framebuffer
update. ie width * height * bytes per pixel. We'll send incremental updates
until we hit this threshold, at which point we'll stop sending updates until
data has been written to the wire, causing the output buffer offset to fall
back below the threshold.

If audio capture is enabled, we increase the size of the threshold to also
allow for upto 1 seconds worth of audio data samples. ie nchannels * bytes
per sample * frequency. This allows the output buffer to have a mixture of
incremental framebuffer updates and audio data queued, but once the threshold
is exceeded, audio data will be dropped and incremental updates will be
throttled.

This unbounded memory growth affects all VNC server configurations supported by
QEMU, with no workaround possible. The mitigating factor is that it can only be
triggered by a client that has authenticated with the VNC server, and who is
able to trigger a large quantity of framebuffer updates or audio samples from
the guest OS. Mostly they'll just succeed in getting the OOM killer to kill
their own QEMU process, but its possible other processes can get taken out as
collateral damage.

This is a more general variant of the similar unbounded memory usage flaw in
the websockets server, that was previously assigned CVE-2017-15268, and fixed
in 2.11 by:

  commit a7b20a8e
  Author: Daniel P. Berrange <berrange@redhat.com>
  Date:   Mon Oct 9 14:43:42 2017 +0100

    io: monitor encoutput buffer size from websocket GSource

This new general memory usage flaw has been assigned CVE-2017-15124, and is
partially fixed by this patch.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-10-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      e2b72cb6
    • D
      ui: refactor code for determining if an update should be sent to the client · 0bad8342
      由 Daniel P. Berrange 提交于 
      The logic for determining if it is possible to send an update to the client
will become more complicated shortly, so pull it out into a separate method
for easier extension later.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-9-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      0bad8342
    • D
      ui: correctly reset framebuffer update state after processing dirty regions · 728a7ac9
      由 Daniel P. Berrange 提交于 
      According to the RFB protocol, a client sends one or more framebuffer update
requests to the server. The server can reply with a single framebuffer update
response, that covers all previously received requests. Once the client has
read this update from the server, it may send further framebuffer update
requests to monitor future changes. The client is free to delay sending the
framebuffer update request if it needs to throttle the amount of data it is
reading from the server.

The QEMU VNC server, however, has never correctly handled the framebuffer
update requests. Once QEMU has received an update request, it will continue to
send client updates forever, even if the client hasn't asked for further
updates. This prevents the client from throttling back data it gets from the
server. This change fixes the flawed logic such that after a set of updates are
sent out, QEMU waits for a further update request before sending more data.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-8-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      728a7ac9
    • D
      ui: introduce enum to track VNC client framebuffer update request state · fef1bbad
      由 Daniel P. Berrange 提交于 
      Currently the VNC servers tracks whether a client has requested an incremental
or forced update with two boolean flags. There are only really 3 distinct
states to track, so create an enum to more accurately reflect permitted states.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-7-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      fef1bbad
    • D
      ui: track how much decoded data we consumed when doing SASL encoding · 8f61f1c5
      由 Daniel P. Berrange 提交于 
      When we encode data for writing with SASL, we encode the entire pending output
buffer. The subsequent write, however, may not be able to send the full encoded
data in one go though, particularly with a slow network. So we delay setting the
output buffer offset back to zero until all the SASL encoded data is sent.

Between encoding the data and completing sending of the SASL encoded data,
however, more data might have been placed on the pending output buffer. So it
is not valid to set offset back to zero. Instead we must keep track of how much
data we consumed during encoding and subtract only that amount.

With the current bug we would be throwing away some pending data without having
sent it at all. By sheer luck this did not previously cause any serious problem
because appending data to the send buffer is always an atomic action, so we
only ever throw away complete RFB protocol messages. In the case of frame buffer
updates we'd catch up fairly quickly, so no obvious problem was visible.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-6-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      8f61f1c5
    • D
      ui: avoid pointless VNC updates if framebuffer isn't dirty · 3541b084
      由 Daniel P. Berrange 提交于 
      The vnc_update_client() method checks the 'has_dirty' flag to see if there are
dirty regions that are pending to send to the client. Regardless of this flag,
if a forced update is requested, updates must be sent. For unknown reasons
though, the code also tries to sent updates if audio capture is enabled. This
makes no sense as audio capture state does not impact framebuffer contents, so
this check is removed.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-5-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      3541b084
    • D
      ui: remove redundant indentation in vnc_client_update · b939eb89
      由 Daniel P. Berrange 提交于 
      Now that previous dead / unreachable code has been removed, we can simplify
the indentation in the vnc_client_update method.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-4-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      b939eb89
    • D
      ui: remove unreachable code in vnc_update_client · c53df961
      由 Daniel P. Berrange 提交于 
      A previous commit:

  commit 5a8be0f7
  Author: Gerd Hoffmann <kraxel@redhat.com>
  Date:   Wed Jul 13 12:21:20 2016 +0200

    vnc: make sure we finish disconnect

Added a check for vs->disconnecting at the very start of the
vnc_update_client method. This means that the very next "if"
statement check for !vs->disconnecting always evaluates true,
and is thus redundant. This in turn means the vs->disconnecting
check at the very end of the method never evaluates true, and
is thus unreachable code.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-3-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      c53df961
    • D
      ui: remove 'sync' parameter from vnc_update_client · 6af998db
      由 Daniel P. Berrange 提交于 
      There is only one caller of vnc_update_client and that always passes false
for the 'sync' parameter.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-2-berrange@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      6af998db
    • M
      vnc: fix debug spelling · 090fdc83
      由 Marc-André Lureau 提交于 
      Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171220140618.12701-1-marcandre.lureau@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
      090fdc83
    • P
      Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging · 36b5e43a
      由 Peter Maydell 提交于 
      pc, pci, virtio: features, fixes, cleanups

A bunch of fixes, cleanus and new features all over the place.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Thu 11 Jan 2018 20:04:57 GMT
# gpg:                using RSA key 0x281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17  0970 C350 3912 AFBE 8E67
#      Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA  8A0D 281F 0DB8 D28D 5469

* remotes/mst/tags/for_upstream: (23 commits)
  smbus: do not immediately complete commands
  dump-guest-memory.py: fix "You can't do that without a process to debug"
  virtio-pci: Don't force Subsystem Vendor ID = Vendor ID
  intel_iommu: fix error param in string
  intel_iommu: remove X86_IOMMU_PCI_DEVFN_MAX
  vhost-user: document memory accesses
  vhost-user: fix indentation in protocol specification
  hw/pci-host/xilinx: QOM'ify the AXI-PCIe host bridge
  hw/pci-host/piix: QOM'ify the IGD Passthrough host bridge
  tests/pxe-test: Add some extra tests
  tests/pxe-test: Test net booting over IPv6 in some cases
  tests/pxe-test: Use table of testcases rather than open-coding
  tests/pxe-test: Remove unnecessary special case test functions
  virtio_error: don't invoke status callbacks
  pci: Eliminate pci_find_primary_bus()
  pci: Eliminate redundant PCIDevice::bus pointer
  pci: Add pci_dev_bus_num() helper
  pci: Move bridge data structures from pci_bus.h to pci_bridge.h
  pci: Rename root bus initialization functions for clarity
  tests: add test to check VirtQueue object
  ...
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
      36b5e43a
    • M
      Merge remote-tracking branch 'origin/master' into HEAD · acc95bc8
      由 Michael S. Tsirkin 提交于 
      Resolve conflicts around apb.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
      acc95bc8
  7. 11 1月, 2018 17 次提交