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  1. 15 6月, 2017 1 次提交
    • E
      nbd: Fix regression on resiliency to port scan · 0c9390d9
      由 Eric Blake 提交于 
      Back in qemu 2.5, qemu-nbd was immune to port probes (a transient
server would not quit, regardless of how many probe connections
came and went, until a connection actually negotiated).  But we
broke that in commit ee7d7aab when removing the return value to
nbd_client_new(), although that patch also introduced a bug causing
an assertion failure on a client that fails negotiation.  We then
made it worse during refactoring in commit 1a6245a5 (a segfault
before we could even assert); the (masked) assertion was cleaned
up in d3780c2d (still in 2.6), and just recently we finally fixed
the segfault ("nbd: Fully intialize client in case of failed
negotiation").  But that still means that ever since we added
TLS support to qemu-nbd, we have been vulnerable to an ill-timed
port-scan being able to cause a denial of service by taking down
qemu-nbd before a real client has a chance to connect.

Since negotiation is now handled asynchronously via coroutines,
we no longer have a synchronous point of return by re-adding a
return value to nbd_client_new().  So this patch instead wires
things up to pass the negotiation status through the close_fn
callback function.

Simple test across two terminals:
$ qemu-nbd -f raw -p 30001 file
$ nmap 127.0.0.1 -p 30001 && \
  qemu-io -c 'r 0 512' -f raw nbd://localhost:30001

Note that this patch does not change what constitutes successful
negotiation (thus, a client must enter transmission phase before
that client can be considered as a reason to terminate the server
when the connection ends).  Perhaps we may want to tweak things
in a later patch to also treat a client that uses NBD_OPT_ABORT
as being a 'successful' negotiation (the client correctly talked
the NBD protocol, and informed us it was not going to use our
export after all), but that's a discussion for another day.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1451614Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <20170608222617.20376-1-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      0c9390d9
  3. 07 6月, 2017 2 次提交
  5. 09 5月, 2017 1 次提交
  7. 02 11月, 2016 7 次提交
    • E
      nbd: Implement NBD_CMD_WRITE_ZEROES on server · 1f4d6d18
      由 Eric Blake 提交于 
      Upstream NBD protocol recently added the ability to efficiently
write zeroes without having to send the zeroes over the wire,
along with a flag to control whether the client wants to allow
a hole.

Note that when it comes to requiring full allocation, vs.
permitting optimizations, the NBD spec intentionally picked a
different sense for the flag; the rules in qemu are:
MAY_UNMAP == 0: must write zeroes
MAY_UNMAP == 1: may use holes if reads will see zeroes

while in NBD, the rules are:
FLAG_NO_HOLE == 1: must write zeroes
FLAG_NO_HOLE == 0: may use holes if reads will see zeroes

In all cases, the 'may use holes' scenario is optional (the
server need not use a hole, and must not use a hole if
subsequent reads would not see zeroes).
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-16-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      1f4d6d18
    • E
      nbd: Improve server handling of shutdown requests · b6f5d3b5
      由 Eric Blake 提交于 
      NBD commit 6d34500b clarified how clients and servers are supposed
to behave before closing a connection. It added NBD_REP_ERR_SHUTDOWN
(for the server to announce it is about to go away during option
haggling, so the client should quit sending NBD_OPT_* other than
NBD_OPT_ABORT) and ESHUTDOWN (for the server to announce it is about
to go away during transmission, so the client should quit sending
NBD_CMD_* other than NBD_CMD_DISC).  It also clarified that
NBD_OPT_ABORT gets a reply, while NBD_CMD_DISC does not.

This patch merely adds the missing reply to NBD_OPT_ABORT and teaches
the client to recognize server errors.  Actually teaching the server
to send NBD_REP_ERR_SHUTDOWN or ESHUTDOWN would require knowing that
the server has been requested to shut down soon (maybe we could do
that by installing a SIGINT handler in qemu-nbd, which transitions
from RUNNING to a new state that waits for the client to react,
rather than just out-right quitting - but that's a bigger task for
another day).
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-15-git-send-email-eblake@redhat.com>
[Move dummy ESHUTDOWN to include/qemu/osdep.h. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      b6f5d3b5
    • E
      nbd: Support shorter handshake · c203c59a
      由 Eric Blake 提交于 
      The NBD Protocol allows the server and client to mutually agree
on a shorter handshake (omit the 124 bytes of reserved 0), via
the server advertising NBD_FLAG_NO_ZEROES and the client
acknowledging with NBD_FLAG_C_NO_ZEROES (only possible in
newstyle, whether or not it is fixed newstyle).  It doesn't
shave much off the wire, but we might as well implement it.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NAlex Bligh <alex@alex.org.uk>
Message-Id: <1476469998-28592-13-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      c203c59a
    • E
      nbd: Share common option-sending code in client · c8a3a1b6
      由 Eric Blake 提交于 
      Rather than open-coding each option request, it's easier to
have common helper functions do the work.  That in turn requires
having convenient packed types for handling option requests
and replies.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-9-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      c8a3a1b6
    • E
      nbd: Rename struct nbd_request and nbd_reply · ed2dd912
      由 Eric Blake 提交于 
      Our coding convention prefers CamelCase names, and we already
have other existing structs with NBDFoo naming.  Let's be
consistent, before later patches add even more structs.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-6-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      ed2dd912
    • E
      nbd: Treat flags vs. command type as separate fields · b626b51a
      由 Eric Blake 提交于 
      Current upstream NBD documents that requests have a 16-bit flags,
followed by a 16-bit type integer; although older versions mentioned
only a 32-bit field with masking to find flags.  Since the protocol
is in network order (big-endian over the wire), the ABI is unchanged;
but dealing with the flags as a separate field rather than masking
will make it easier to add support for upcoming NBD extensions that
increase the number of both flags and commands.

Improve some comments in nbd.h based on the current upstream
NBD protocol (https://github.com/yoe/nbd/blob/master/doc/proto.md),
and touch some nearby code to keep checkpatch.pl happy.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-3-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      b626b51a
    • E
      nbd: Add qemu-nbd -D for human-readable description · b1a75b33
      由 Eric Blake 提交于 
      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: NEric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-2-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      b1a75b33
  9. 06 9月, 2016 1 次提交
    • K
      nbd-server: Use a separate BlockBackend · cd7fca95
      由 Kevin Wolf 提交于 
      The builtin NBD server uses its own BlockBackend now instead of reusing
the monitor/guest device one.

This means that it has its own writethrough setting now. The builtin
NBD server always uses writeback caching now regardless of whether the
guest device has WCE enabled. qemu-nbd respects the cache mode given on
the command line.

We still need to keep a reference to the monitor BB because we put an
eject notifier on it, but we don't use it for any I/O.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
      cd7fca95
  11. 04 8月, 2016 1 次提交
    • E
      nbd: Limit nbdflags to 16 bits · 7423f417
      由 Eric Blake 提交于 
      Rather than asserting that nbdflags is within range, just give
it the correct type to begin with :)  nbdflags corresponds to
the per-export portion of NBD Protocol "transmission flags", which
is 16 bits in response to NBD_OPT_EXPORT_NAME and NBD_OPT_GO.

Furthermore, upstream NBD has never passed the global flags to
the kernel via ioctl(NBD_SET_FLAGS) (the ioctl was first
introduced in NBD 2.9.22; then a latent bug in NBD 3.1 actually
tried to OR the global flags with the transmission flags, with
the disaster that the addition of NBD_FLAG_NO_ZEROES in 3.9
caused all earlier NBD 3.x clients to treat every export as
read-only; NBD 3.10 and later intentionally clip things to 16
bits to pass only transmission flags).  Qemu should follow suit,
since the current two global flags (NBD_FLAG_FIXED_NEWSTYLE
and NBD_FLAG_NO_ZEROES) have no impact on the kernel's behavior
during transmission.

CC: qemu-stable@nongnu.org
Signed-off-by: NEric Blake <eblake@redhat.com>

Message-Id: <1469129688-22848-3-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      7423f417
  13. 20 7月, 2016 2 次提交
  15. 05 7月, 2016 1 次提交
  17. 17 6月, 2016 2 次提交
    • E
      nbd: Avoid magic number for NBD max name size · 943cec86
      由 Eric Blake 提交于 
      Declare a constant and use that when determining if an export
name fits within the constraints we are willing to support.

Note that upstream NBD recently documented that clients MUST
support export names of 256 bytes (not including trailing NUL),
and SHOULD support names up to 4096 bytes.  4096 is a bit big
(we would lose benefits of stack-allocation of a name array),
and we already have other limits in place (for example, qcow2
snapshot names are clamped around 1024).  So for now, just
stick to the required minimum, as that's easier to audit than
a full-scale support for larger names.
Signed-off-by: NEric Blake <eblake@redhat.com>

Message-Id: <1463006384-7734-12-git-send-email-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      943cec86
    • P
      nbd: simplify the nbd_request and nbd_reply structs · 56af2dda
      由 Paolo Bonzini 提交于 
      These structs are never used to represent the bytes that go over the
network.  The big-endian network data is built into a uint8_t array
in nbd_{receive,send}_{request,reply}.  Remove the unused magic field,
reorder the struct to avoid holes, and remove the packed attribute.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      56af2dda
  19. 23 2月, 2016 1 次提交
    • P
      include: Clean up includes · 90ce6e26
      由 Peter Maydell 提交于 
      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.

NB: If this commit breaks compilation for your out-of-tree
patchseries or fork, then you need to make sure you add
#include "qemu/osdep.h" to any new .c files that you have.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
      90ce6e26
  21. 17 2月, 2016 2 次提交
  23. 16 1月, 2016 1 次提交
    • F
      nbd: Always call "close_fn" in nbd_client_new · ee7d7aab
      由 Fam Zheng 提交于 
      Rename the parameter "close" to "close_fn" to disambiguous with
close(2).

This unifies error handling paths of NBDClient allocation:
nbd_client_new will shutdown the socket and call the "close_fn" callback
if negotiation failed, so the caller don't need a different path than
the normal close.

The returned pointer is never used, make it void in preparation for the
next patch.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-Id: <1452760863-25350-2-git-send-email-famz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      ee7d7aab
  25. 18 3月, 2015 3 次提交
  27. 16 2月, 2015 1 次提交
    • M
      nbd: Drop BDS backpointer · f53a829b
      由 Max Reitz 提交于 
      Before this patch, the "opaque" pointer in an NBD BDS points to a
BDRVNBDState, which contains an NbdClientSession object, which in turn
contains a pointer to the BDS. This pointer may become invalid due to
bdrv_swap(), so drop it, and instead pass the BDS directly to the
nbd-client.c functions which then retrieve the NbdClientSession object
from there.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1423256778-3340-2-git-send-email-mreitz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      f53a829b
  29. 07 2月, 2015 1 次提交
    • M
      nbd: Improve error messages · 1ce52846
      由 Max Reitz 提交于 
      This patch makes use of the Error object for nbd_receive_negotiate() so
that errors during negotiation look nicer.

Furthermore, this patch adds an additional error message if the received
magic was wrong, but would be correct for the other protocol version,
respectively: So if an export name was specified, but the NBD server
magic corresponds to an old handshake, this condition is explicitly
signaled to the user, and vice versa.

As these messages are now part of the "Could not open image" error
message, additional filtering has to be employed in iotest 083, which
this patch does as well.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      1ce52846
  31. 10 12月, 2014 1 次提交
  33. 30 6月, 2014 2 次提交
  35. 22 2月, 2014 3 次提交
  37. 03 5月, 2013 1 次提交
    • S
      nbd: support large NBD requests · 2d821488
      由 Stefan Hajnoczi 提交于 
      The Linux nbd driver recently increased the maximum supported request
size up to 32 MB:

  commit 078be02b80359a541928c899c2631f39628f56df
  Author: Michal Belczyk <belczyk@bsd.krakow.pl>
  Date:   Tue Apr 30 15:28:28 2013 -0700

      nbd: increase default and max request sizes

      Raise the default max request size for nbd to 128KB (from 127KB) to get it
      4KB aligned.  This patch also allows the max request size to be increased
      (via /sys/block/nbd<x>/queue/max_sectors_kb) to 32MB.

QEMU's 1 MB buffers are too small to handle these requests.

This patch allocates data buffers dynamically and allows up to 32 MB per
request.
Reported-by: NNick Thomas <nick@bytemark.co.uk>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      2d821488
  39. 23 3月, 2013 2 次提交
  41. 19 12月, 2012 1 次提交
  43. 19 9月, 2012 3 次提交