There's enough drivers with a sector-based callback that it will
be easier to switch one at a time.  This patch adds a byte-based
callback, and then after all drivers are swapped, we'll drop the
sector-based callback.

[checkpatch doesn't like the space after coroutine_fn in
block_int.h, but it's consistent with the rest of the file]
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-10-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Another step towards byte-based interfaces everywhere.  Replace
the sector-based driver callback .bdrv_aio_discard() with a new
byte-based .bdrv_aio_pdiscard().  Only raw-posix and RBD drivers
are affected, so it was not worth splitting into multiple patches.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-9-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The internal function converts to byte-based before calling into
RBD code; hoist the conversion to the callers so that callers
can then be switched to byte-based themselves.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-8-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The only remaining uses of paio_submit() were flush (with no
offset or count) and discard (which we are switching to byte-based);
furthermore, the similarly named paio_submit_co() is already
byte-based.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-7-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Change sector-based blk_discard(), blk_co_discard(), and
blk_aio_discard() to instead be byte-based blk_pdiscard(),
blk_co_pdiscard(), and blk_aio_pdiscard().  NBD gets a lot
simpler now that ignoring the unaligned portion of a
byte-based discard request is handled under the hood by
the block layer.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-6-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Another step towards byte-based interfaces everywhere.  Replace
the sector-based bdrv_aio_discard() with a new byte-based
bdrv_aio_pdiscard(), which silently ignores any unaligned head
or tail.  Driver callbacks will be converted in followup patches.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-id: 1468624988-423-5-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

BlockRequest is the internal struct used by bdrv_aio_*.  At the
moment, all such calls were sector-based, but we will eventually
convert to byte-based; start by changing the internal variables
to be byte-based.  No change to behavior, although the read and
write code can now go byte-based through more of the stack.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-id: 1468624988-423-4-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Another step towards byte-based interfaces everywhere.  Replace
the sector-based bdrv_discard() with a new byte-based
bdrv_pdiscard(), which silently ignores any unaligned head
or tail.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-3-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Another step towards byte-based interfaces everywhere.  Replace
the sector-based bdrv_co_discard() with a new byte-based
bdrv_co_pdiscard(), which silently ignores any unaligned head
or tail.  Driver callbacks will be converted in followup patches.

By calculating the alignment outside of the loop, and clamping
the max discard to an aligned value, we can simplify the actions
done within the loop.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-2-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Now that the block layer honors max_request, we don't need to
bother with an EINVAL on overlarge requests, but can instead
assert that requests are well-behaved.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1468607524-19021-7-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Now that NBD relies on the block layer to fragment things, we no
longer need to track an offset argument for which fragment of
a request we are actually servicing.

While at it, use true and false instead of 0 and 1 for a bool
parameter.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1468607524-19021-6-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Now that the block layer will honor max_transfer, we can simplify
our code to rely on that guarantee.

The readv code can call directly into nbd-client, just as the
writev code has done since commit 52a46505.

Interestingly enough, while qemu-io 'w 0 40m' splits into a 32M
and 8M transaction, 'w -z 0 40m' splits into two 16M and an 8M,
because the block layer caps the bounce buffer for writing zeroes
at 16M.  When we later introduce support for NBD_CMD_WRITE_ZEROES,
we can get a full 32M zero write (or larger, if the client and
server negotiate that write zeroes can use a larger size than
ordinary writes).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1468607524-19021-5-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Drivers should be able to rely on the block layer honoring the
max transfer length, rather than needing to return -EINVAL
(iscsi) or manually fragment things (nbd).  We already fragment
write zeroes at the block layer; this patch adds the fragmentation
for normal writes, after requests have been aligned (fragmenting
before alignment would lead to multiple unaligned requests, rather
than just the head and tail).

When fragmenting a large request where FUA was requested, but
where we know that FUA is implemented by flushing all requests
rather than the given request, then we can still get by with
only one flush.  Note, however, that we need a followup patch
to the raw format driver to avoid a regression in the number of
flushes actually issued.

The return value was previously nebulous on success (sometimes
zero, sometimes the length written); since we never have a short
write, and since fragmenting may store yet another positive
value in 'ret', change the function to always return 0 on success,
matching what we do in bdrv_aligned_preadv().
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-id: 1468607524-19021-4-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The raw format layer supports all flags via passthrough - but
it only makes sense to pass through flags that the lower layer
actually supports.

The next patch gives stronger reasoning for why this is correct.
At the moment, the raw format layer ignores the max_transfer
limit of its protocol layer, and an attempt to do the qemu-io
'w -f 0 40m' to an NBD server that lacks FUA will pass the entire
40m request to the NBD driver, which then fragments the request
itself into a 32m write, 8m write, and flush.  But once the block
layer starts honoring limits and fragmenting packets, the raw
driver will hand the NBD driver two separate requests; if both
requests have BDRV_REQ_FUA set, then this would result in a 32m
write, flush, 8m write, and second flush.  By having the raw
layer no longer advertise FUA support when the protocol layer
lacks it, we are back to a single flush at the block layer for
the overall 40m request.

Note that 'w -f -z 0 40m' does not currently exhibit the same
problem, because there, the fragmentation does not occur until
at the NBD layer (the raw layer has .bdrv_co_pwrite_zeroes, and
the NBD layer doesn't advertise max_pwrite_zeroes to constrain
things at the raw layer) - but the problem is latent and we
would again have too many flushes without this patch once the
NBD layer implements support for the new NBD_CMD_WRITE_ZEROES
command, if it sets max_pwrite_zeroes to the same 32m limit as
recommended by the NBD protocol.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468607524-19021-3-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Drivers should be able to rely on the block layer honoring the
max transfer length, rather than needing to return -EINVAL
(iscsi) or manually fragment things (nbd).  This patch adds
the fragmentation in the block layer, after requests have been
aligned (fragmenting before alignment would lead to multiple
unaligned requests, rather than just the head and tail).

The return value was previously nebulous on success on whether
it was zero or the length read; and fragmenting may introduce
yet other non-zero values if we use the last length read.  But
as at least some callers are sloppy and expect only zero on
success, it is easiest to just guarantee 0.

[Fix uninitialized ret local variable in bdrv_aligned_preadv().
--Stefan]
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-id: 1468607524-19021-2-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

target-arm queue:
 * fix two minor Coverity complaints

# gpg: Signature made Tue 19 Jul 2016 18:02:34 BST
# gpg:                using RSA key 0x3C2525ED14360CDE
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>"
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>"
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>"
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-target-arm-20160719:
  arm_gicv3: Add assert()s to tell Coverity that offsets are aligned
  target-arm: Fix unreachable code in gicv3_class_name()
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

linux-user fixes before 2.7 freeze, fix commit message

# gpg: Signature made Tue 19 Jul 2016 14:18:54 BST
# gpg:                using RSA key 0xB44890DEDE3C9BC0
# gpg: Good signature from "Riku Voipio <riku.voipio@iki.fi>"
# gpg:                 aka "Riku Voipio <riku.voipio@linaro.org>"
# Primary key fingerprint: FF82 03C8 C391 98AE 0581  41EF B448 90DE DE3C 9BC0

* remotes/riku/tags/pull-linux-user-20160719-2:
  linux-user: AArch64 has sync_file_range, not sync_file_range2
  linux-user: Fix type for SIOCATMARK ioctl
  linux-user: define missing sparc syscalls
  linux-user: Fix terminal control ioctls
  linux-user: Add some new blk ioctls
  linux-user: Handle short lengths in host_to_target_sockaddr()
  linux-user: Forget about synchronous signal once it is delivered
  linux-user: Correct type for LOOP_GET_STATUS{,64} ioctls
  linux-user: Correct type for BLKSSZGET
  linux-user: Add loop control ioctls
  linux-user: Check sigsetsize argument to syscalls
  linux-user: add nested netlink types
  linux-user: convert sockaddr_ll from host to target
  linux-user: add fd_trans helper in do_recvfrom()
  linux-user: fix netlink memory corruption
  linux-user: fd_trans_*_data() returns the length
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Coverity complains that the GICR_IPRIORITYR case in gicv3_readl()
can overflow an array, because it doesn't know that the offsets
passed to that function must be word aligned. Add some assert()s
which hopefully tell Coverity that this isn't possible.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1468261372-17508-1-git-send-email-peter.maydell@linaro.org

Coverity complains that the exit() in gicv3_class_name()
can be unreachable, because if TARGET_AARCH64 is defined
then all code paths return before reaching it. Move the
exit() up to the error_report() that it belongs with.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NShannon Zhao <shannon.zhao@linaro.org>
Message-id: 1468260552-8400-1-git-send-email-peter.maydell@linaro.org

disas/bfd.h defines ATTRIBUTE_UNUSED, but unfortunately the
ALSA system headers also define this macro, which means that
you can get a compilation failure if building with ALSA and
any files happen to include the alsa headers before bfd.h
rather than the other way around.

This is unfortunate namespace pollution by the ALSA headers but
we can work around it. Add an #ifndef guard to bfd.h and remove
the unnecessary extra definition in disas/arm.c to fix this.
Reported-by: NBALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468937076-21503-1-git-send-email-peter.maydell@linaro.org

* two old patches from prospective GSoC students
* i386 -kernel device tree support
* Coverity fix
* memory usage improvement from Peter
* checkpatch fix
* g_path_get_dirname cleanup
* caching of block status for iSCSI

# gpg: Signature made Tue 19 Jul 2016 07:43:41 BST
# gpg:                using RSA key 0xBFFBD25F78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>"
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* remotes/bonzini/tags/for-upstream:
  target-i386: Remove redundant HF_SOFTMMU_MASK
  block/iscsi: allow caching of the allocation map
  block/iscsi: fix rounding in iscsi_allocationmap_set
  Move README to markdown
  cpu-exec: Move down some declarations in cpu_exec()
  exec: avoid realloc in phys_map_node_reserve
  checkpatch: consider git extended headers valid patches
  megasas: remove useless check for cmd->frame
  compiler: never omit assertions if using a static analysis tool
  hw/i386: add device tree support
  Changed malloc to g_malloc, free to g_free in bsd-user/qemu.h
  use g_path_get_dirname instead of dirname
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Make IRC a little less noisy

# gpg: Signature made Mon 18 Jul 2016 16:42:57 BST
# gpg:                using RSA key 0xFBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>"
# Primary key fingerprint: 6685 AE99 E751 67BC AFC8  DF35 FBD0 DB09 5A9E 2A44

* remotes/stsquad/tags/pull-travis-20160718-1:
  .travis.yml: Disable IRC build status updates from forks
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

The AArch64 Linux ABI syscall 84 is sync_file_range, not
sync_file_range2 (in the kernel it uses the asm-generic
headers and does not define __ARCH_WANT_SYNC_FILE_RANGE2).
Update our TARGET_NR_* definitions accordingly.

This fixes the sync_file_range syscall which otherwise
gets its arguments in the wrong order.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

The SIOCATMARK ioctl takes an argument which should be a
pointer to an integer where the kernel will write the result.
We were incorrectly declaring it as TYPE_NULL which would mean
it would always fail (with EFAULT) when it should succeed.
Correct the type.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

NR_lookup_dcookie, NR_fadvise64, NR_fadvise64_64
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

TIOCGPTN and related terminal control ioctls were not converted to the guest ioctl format on x86_64 targets. Convert these ioctls to enable terminal functionality on x86_64 guests.
Signed-off-by: NTimothy Pearson <tpearson@raptorengineering.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

vnc: bugfixes for -rc0

# gpg: Signature made Tue 19 Jul 2016 08:27:05 BST
# 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/pull-vnc-20160719-1:
  vnc-tight: fix regression with libxenstore
  vnc-enc-tight: fix off-by-one bug
  vnc: make sure we finish disconnect
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Update OpenBIOS images

# gpg: Signature made Tue 19 Jul 2016 07:42:30 BST
# gpg:                using RSA key 0x5BC2C56FAE0F321F
# gpg: Good signature from "Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>"
# Primary key fingerprint: CC62 1AB9 8E82 200D 915C  C9C4 5BC2 C56F AE0F 321F

* remotes/mcayland/tags/qemu-openbios-signed:
  Update OpenBIOS images to e79bca6 built from submodule.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add some new blk ioctls (these are 0x12,119 through
to 0x12,127). Several of these are used by mke2fs; this silences
the warnings:

mke2fs 1.42.12 (29-Aug-2014)
Unsupported ioctl: cmd=0x127b
Unsupported ioctl: cmd=0x127a
warning: Unable to get device geometry for /dev/loop5
Unsupported ioctl: cmd=0x127c
Unsupported ioctl: cmd=0x127c
Unsupported ioctl: cmd=0x1277
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

If userspace specifies a short buffer for a target sockaddr,
the kernel will only copy in as much as it has space for
(or none at all if the length is zero) -- see the kernel
move_addr_to_user() function. Mimic this in QEMU's
host_to_target_sockaddr() routine.

In particular, this fixes a segfault running the LTP
recvfrom01 test, where the guest makes a recvfrom()
call with a bad buffer pointer and other parameters which
cause the kernel to set the addrlen to zero; because we
did not skip the attempt to swap the sa_family field we
segfaulted on the bad address.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Commit 655ed67c which switched synchronous signals to
benig recorded in ts->sync_signal rather than in a queue
with every other signal had a bug: we failed to clear
the flag indicating that a synchronous signal was pending
when we delivered it. This meant that we would take the signal
again and again every time the guest made a syscall.
(This is a bug introduced in my refactoring of Timothy Baldwin's
original code.)

Fix this by passing in the struct emulated_sigtable* to
handle_pending_signal(), so that we clear the pending flag
in the ts->sync_signal struct when handling a synchronous signal.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

The LOOP_GET_STATUS and LOOP_GET_STATUS64 ioctls were incorrectly
defined as IOC_W rather than IOC_R, which meant we weren't
correctly copying the information back from the kernel to the guest.
The loop_info64 structure definition was also missing a member
and using the wrong type for several 32-bit fields.

In particular, this meant that "kpartx -d image.img" didn't work
and "losetup -a" behaved strangely. Correct the ioctl type definitions.
Reported-by: NChanho Park <chanho61.park@samsung.com>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

The BLKSSZGET ioctl takes an argument which is a pointer to an int.
We were incorrectly declaring it to take a pointer to a long, which
meant that we would incorrectly write to memory which we should not
if the guest is a 64-bit architecture.

In particular, kpartx uses this ioctl to write to an int on the
stack, which tends to result in it crashing immediately.
Reported-by: NChanho Park <chanho61.park@samsung.com>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Add support for the /dev/loop-control ioctls:
 LOOP_CTL_ADD
 LOOP_CTL_REMOVE
 LOOP_CTL_GET_FREE

[RV: fixed to apply to new header guards]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Many syscalls which take a sigset_t argument also take an argument
giving the size of the sigset_t.  The kernel insists that this
matches its idea of the type size and fails EINVAL if it is not.
Implement this logic in QEMU.  (This mostly just means some LTP test
cases which check error cases now pass.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>

Nested types are used by the kernel to send link information and
protocol properties.

We can see following errors with "ip link show":

Unimplemented nested type 26
Unimplemented nested type 26
Unimplemented nested type 18
Unimplemented nested type 26
Unimplemented nested type 18
Unimplemented nested type 26

This patch implements nested types 18 (IFLA_LINKINFO) and
26 (IFLA_AF_SPEC).
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

As we convert sockaddr for AF_PACKET family for sendto() (target to
host) we need also to convert this for getsockname() (host to target).

arping uses getsockname() to get the the interface address and uses
this address with sendto().

Tested with:

    /sbin/arping -D -q -c2 -I eno1 192.168.122.88

...
getsockname(3, {sa_family=AF_PACKET, proto=0x806, if2,
pkttype=PACKET_HOST, addr(6)={1, 10c37b6b9a76}, [18]) = 0
...
sendto(3, "..." 28, 0,
       {sa_family=AF_PACKET, proto=0x806, if2, pkttype=PACKET_HOST,
       addr(6)={1, ffffffffffff}, 20) = 28
...
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Fix passwd using netlink audit.
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Netlink is byte-swapping data in the guest memory (it's bad).

It's ok when the data come from the host as they are generated by the
host.

But it doesn't work when data come from the guest: the guest can
try to reuse these data whereas they have been byte-swapped.

This is what happens in glibc:

glibc generates a sequence number in nlh.nlmsg_seq and calls
sendto() with this nlh. In sendto(), we byte-swap nlmsg.seq.

Later, after the recvmsg(), glibc compares nlh.nlmsg_seq with
sequence number given in return, and of course it fails (hangs),
because nlh.nlmsg_seq is not valid anymore.

The involved code in glibc is:

sysdeps/unix/sysv/linux/check_pf.c:make_request()
...
  req.nlh.nlmsg_seq = time (NULL);
...
  if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0,
                                    (struct sockaddr *) &nladdr,
                                    sizeof (nladdr))) < 0)
<here req.nlh.nlmsg_seq has been byte-swapped>
...
  do
    {
...
      ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0));
...
      struct nlmsghdr *nlmh;
      for (nlmh = (struct nlmsghdr *) buf;
           NLMSG_OK (nlmh, (size_t) read_len);
           nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len))
        {
<we compare nlmh->nlmsg_seq with corrupted req.nlh.nlmsg_seq>
          if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != pid
              || nlmh->nlmsg_seq != req.nlh.nlmsg_seq)
            continue;
...
          else if (nlmh->nlmsg_type == NLMSG_DONE)
            /* We found the end, leave the loop.  */
            done = true;
        }
    }
  while (! done);

As we have a continue on "nlmh->nlmsg_seq != req.nlh.nlmsg_seq",
"done" cannot be set to "true" and we have an infinite loop.

It's why commands like "apt-get update" or "dnf update hangs".
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

fd_trans_target_to_host_data() and fd_trans_host_to_target_data() must
return the length of processed data.
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>