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  1. 28 4月, 2015 3 次提交
  3. 27 3月, 2015 1 次提交
    • F
      block: Fix unaligned zero write · fc3959e4
      由 Fam Zheng 提交于 
      If the zero write is not aligned, bdrv_co_do_pwritev will segfault
because of accessing to the NULL qiov passed in by bdrv_co_write_zeroes.
Fix this by allocating a local qiov in bdrv_co_do_pwritev if the request
is not aligned. (In this case the padding iovs are necessary anyway, so
it doesn't hurt.)

Also add a check at the end of bdrv_co_do_pwritev to clear the zero flag
if padding is involved.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-id: 1427160230-4489-2-git-send-email-famz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      fc3959e4
  5. 17 3月, 2015 2 次提交
    • F
      block: Drop bdrv_find · d51a2427
      由 Fam Zheng 提交于 
      All callers are converted, so drop it.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-id: 1425296209-1476-5-git-send-email-famz@redhat.com
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>
      d51a2427
    • M
      block: Deprecate QCOW/QCOW2 encryption · a1f688f4
      由 Markus Armbruster 提交于 
      We've steered users away from QCOW/QCOW2 encryption for a while,
because it's a flawed design (commit 136cd19d Describe flaws in
qcow/qcow2 encryption in the docs).

In addition to flawed crypto, we have comically bad usability, and
plain old bugs.  Let me show you.

= Example images =

I'm going to use a raw image as backing file, and two QCOW2 images,
one encrypted, and one not:

    $ qemu-img create -f raw backing.img 4m
    Formatting 'backing.img', fmt=raw size=4194304
    $ qemu-img create -f qcow2 -o encryption,backing_file=backing.img,backing_fmt=raw geheim.qcow2 4m
    Formatting 'geheim.qcow2', fmt=qcow2 size=4194304 backing_file='backing.img' backing_fmt='raw' encryption=on cluster_size=65536 lazy_refcounts=off
    $ qemu-img create -f qcow2 -o backing_file=backing.img,backing_fmt=raw normal.qcow2 4m
    Formatting 'normal.qcow2', fmt=qcow2 size=4194304 backing_file='backing.img' backing_fmt='raw' encryption=off cluster_size=65536 lazy_refcounts=off

= Usability issues =

== Confusing startup ==

When no image is encrypted, and you don't give -S, QEMU starts the
guest immediately:

    $ qemu-system-x86_64 -nodefaults -display none -monitor stdio normal.qcow2
    QEMU 2.2.50 monitor - type 'help' for more information
    (qemu) info status
    VM status: running

But as soon as there's an encrypted image in play, the guest is *not*
started, with no notification whatsoever:

    $ qemu-system-x86_64 -nodefaults -display none -monitor stdio geheim.qcow2
    QEMU 2.2.50 monitor - type 'help' for more information
    (qemu) info status
    VM status: paused (prelaunch)

If the user figured out that he needs to type "cont" to enter his
keys, the confusion enters the next level: "cont" asks for at most
*one* key.  If more are needed, it then silently does nothing.  The
user has to type "cont" once per encrypted image:

    $ qemu-system-x86_64 -nodefaults -display none -monitor stdio -drive if=none,file=geheim.qcow2 -drive if=none,file=geheim.qcow2
    QEMU 2.2.50 monitor - type 'help' for more information
    (qemu) info status
    VM status: paused (prelaunch)
    (qemu) c
    none0 (geheim.qcow2) is encrypted.
    Password: ******
    (qemu) info status
    VM status: paused (prelaunch)
    (qemu) c
    none1 (geheim.qcow2) is encrypted.
    Password: ******
    (qemu) info status
    VM status: running

== Incorrect passwords not caught ==

All existing encryption schemes give you the GIGO treatment: garbage
password in, garbage data out.  Guests usually refuse to mount
garbage, but other usage is prone to data loss.

== Need to stop the guest to add an encrypted image ==

    $ qemu-system-x86_64 -nodefaults -display none -monitor stdio
    QEMU 2.2.50 monitor - type 'help' for more information
    (qemu) info status
    VM status: running
    (qemu) drive_add "" if=none,file=geheim.qcow2
    Guest must be stopped for opening of encrypted image
    (qemu) stop
    (qemu) drive_add "" if=none,file=geheim.qcow2
    OK

Commit c3adb58f added this restriction.  Before, we could expose images
lacking an encryption key to guests, with potentially catastrophic
results.  See also "Use without key is not always caught".

= Bugs =

== Use without key is not always caught ==

Encrypted images can be in an intermediate state "opened, but no key".
The weird startup behavior and the need to stop the guest are there to
ensure the guest isn't exposed to that state.  But other things still
are!

* drive_backup

    $ qemu-system-x86_64 -nodefaults -display none -monitor stdio geheim.qcow2
    QEMU 2.2.50 monitor - type 'help' for more information
    (qemu) drive_backup -f ide0-hd0 out.img raw
    Formatting 'out.img', fmt=raw size=4194304

  I guess this writes encrypted data to raw image out.img.  Good luck
  with figuring out how to decrypt that again.

* commit

    $ qemu-system-x86_64 -nodefaults -display none -monitor stdio geheim.qcow2
    QEMU 2.2.50 monitor - type 'help' for more information
    (qemu) commit ide0-hd0

  I guess this writes encrypted data into the unencrypted raw backing
  image, effectively destroying it.

== QMP device_add of usb-storage fails when it shouldn't ==

When the image is encrypted, device_add creates the device, defers
actually attaching it to when the key becomes available, then fails.
This is wrong.  device_add must either create the device and succeed,
or do nothing and fail.

    $ qemu-system-x86_64 -nodefaults -display none -usb -qmp stdio -drive if=none,id=foo,file=geheim.qcow2
    {"QMP": {"version": {"qemu": {"micro": 50, "minor": 2, "major": 2}, "package": ""}, "capabilities": []}}
    { "execute": "qmp_capabilities" }
    {"return": {}}
    { "execute": "device_add", "arguments": { "driver": "usb-storage", "id": "bar", "drive": "foo" } }
    {"error": {"class": "DeviceEncrypted", "desc": "'foo' (geheim.qcow2) is encrypted"}}
    {"execute":"device_del","arguments": { "id": "bar" } }
    {"timestamp": {"seconds": 1426003440, "microseconds": 237181}, "event": "DEVICE_DELETED", "data": {"path": "/machine/peripheral/bar/bar.0/legacy[0]"}}
    {"timestamp": {"seconds": 1426003440, "microseconds": 238231}, "event": "DEVICE_DELETED", "data": {"device": "bar", "path": "/machine/peripheral/bar"}}
    {"return": {}}

This stuff is worse than useless, it's a trap for users.

If people become sufficiently interested in encrypted images to
contribute a cryptographically sane implementation for QCOW2 (or
whatever other format), then rewriting the necessary support around it
from scratch will likely be easier and yield better results than
fixing up the existing mess.

Let's deprecate the mess now, drop it after a grace period, and move
on.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      a1f688f4
  7. 10 3月, 2015 1 次提交
  9. 26 2月, 2015 4 次提交
  11. 16 2月, 2015 3 次提交
  13. 07 2月, 2015 5 次提交
  15. 24 1月, 2015 1 次提交
  17. 13 1月, 2015 7 次提交
  19. 13 12月, 2014 1 次提交
  21. 12 12月, 2014 1 次提交
    • M
      vmdk: Fix error for JSON descriptor file names · 5c98415b
      由 Max Reitz 提交于 
      If vmdk blindly tries to use path_combine() using bs->file->filename as
the base file name, this will result in a bad error message for JSON
file names when calling bdrv_open(). It is better to only try
bs->file->exact_filename; if that is empty, bs->file->filename will be
useless for path_combine() and an error should be emitted (containing
bs->file->filename because desc_file_path (which is
bs->file->exact_filename) is empty).
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 1417615043-26174-2-git-send-email-mreitz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      5c98415b
  23. 10 12月, 2014 8 次提交
  25. 14 11月, 2014 1 次提交
  27. 11 11月, 2014 1 次提交
  29. 06 11月, 2014 1 次提交