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  • Anton Anton anjo
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  1. Jun 04, 2021
  3. Jul 15, 2020
    • Daniel P. Berrangé's avatar
      net: detect errors from probing vnet hdr flag for TAP devices · e7b347d0
      Daniel P. Berrangé authored 
      
When QEMU sets up a tap based network device backend, it mostly ignores errors
reported from various ioctl() calls it makes, assuming the TAP file descriptor
is valid. This assumption can easily be violated when the user is passing in a
pre-opened file descriptor. At best, the ioctls may fail with a -EBADF, but if
the user passes in a bogus FD number that happens to clash with a FD number that
QEMU has opened internally for another reason, a wide variety of errnos may
result, as the TUNGETIFF ioctl number may map to a completely different command
on a different type of file.

By ignoring all these errors, QEMU sets up a zombie network backend that will
never pass any data. Even worse, when QEMU shuts down, or that network backend
is hot-removed, it will close this bogus file descriptor, which could belong to
another QEMU device backend.

There's no obvious guaranteed reliable way to detect that a FD genuinely is a
TAP device, as opposed to a UNIX socket, or pipe, or something else. Checking
the errno from probing vnet hdr flag though, does catch the big common cases.
ie calling TUNGETIFF will return EBADF for an invalid FD, and ENOTTY when FD is
a UNIX socket, or pipe which catches accidental collisions with FDs used for
stdio, or monitor socket.

Previously the example below where bogus fd 9 collides with the FD used for the
chardev saw:

$ ./x86_64-softmmu/qemu-system-x86_64 -netdev tap,id=hostnet0,fd=9 \
  -chardev socket,id=charchannel0,path=/tmp/qga,server,nowait \
  -monitor stdio -vnc :0
qemu-system-x86_64: -netdev tap,id=hostnet0,fd=9: TUNGETIFF ioctl() failed: Inappropriate ioctl for device
TUNSETOFFLOAD ioctl() failed: Bad address
QEMU 2.9.1 monitor - type 'help' for more information
(qemu) Warning: netdev hostnet0 has no peer

which gives a running QEMU with a zombie network backend.

With this change applied we get an error message and QEMU immediately exits
before carrying on and making a bigger disaster:

$ ./x86_64-softmmu/qemu-system-x86_64 -netdev tap,id=hostnet0,fd=9 \
  -chardev socket,id=charchannel0,path=/tmp/qga,server,nowait \
  -monitor stdio -vnc :0
qemu-system-x86_64: -netdev tap,id=hostnet0,vhost=on,fd=9: Unable to query TUNGETIFF on FD 9: Inappropriate ioctl for device

Reported-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Tested-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Message-id: 20171027085548.3472-1-berrange@redhat.com
[lv: to simplify, don't check on EINVAL with TUNGETIFF as it exists since v2.6.27]
Signed-off-by: default avatarLaurent Vivier <lvivier@redhat.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
      e7b347d0
  5. Jun 12, 2019
    • Markus Armbruster's avatar
      Include qemu-common.h exactly where needed · a8d25326
      Markus Armbruster authored 
      
No header includes qemu-common.h after this commit, as prescribed by
qemu-common.h's file comment.

Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
Message-Id: <20190523143508.25387-5-armbru@redhat.com>
[Rebased with conflicts resolved automatically, except for
include/hw/arm/xlnx-zynqmp.h hw/arm/nrf51_soc.c hw/arm/msf2-soc.c
block/qcow2-refcount.c block/qcow2-cluster.c block/qcow2-cache.c
target/arm/cpu.h target/lm32/cpu.h target/m68k/cpu.h target/mips/cpu.h
target/moxie/cpu.h target/nios2/cpu.h target/openrisc/cpu.h
target/riscv/cpu.h target/tilegx/cpu.h target/tricore/cpu.h
target/unicore32/cpu.h target/xtensa/cpu.h; bsd-user/main.c and
net/tap-bsd.c fixed up]
      a8d25326
  7. Mar 02, 2018
  9. Feb 09, 2018
  11. Jul 12, 2016
  13. Jun 17, 2015
  15. May 27, 2015
  17. Nov 02, 2014
  19. Feb 01, 2013
    • Jason Wang's avatar
      tap: multiqueue support · 264986e2
      Jason Wang authored 
      
Recently, linux support multiqueue tap which could let userspace call TUNSETIFF
for a signle device many times to create multiple file descriptors as
independent queues. User could also enable/disabe a specific queue through
TUNSETQUEUE.

The patch adds the generic infrastructure to create multiqueue taps. To achieve
this a new parameter "queues" were introduced to specify how many queues were
expected to be created for tap by qemu itself. Alternatively, management could
also pass multiple pre-created tap file descriptors separated with ':' through a
new parameter fds like -netdev tap,id=hn0,fds="X:Y:..:Z". Multiple vhost file
descriptors could also be passed in this way.

Each TAPState were still associated to a tap fd, which mean multiple TAPStates
were created when user needs multiqueue taps. Since each TAPState contains one
NetClientState, with the multiqueue nic support, an N peers of NetClientState
were built up.

A new parameter, mq_required were introduce in tap_open() to create multiqueue
tap fds.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
      264986e2
    • Jason Wang's avatar
      tap: introduce a helper to get the name of an interface · e5dc0b40
      Jason Wang authored 
      
This patch introduces a helper tap_get_ifname() to get the device name of tap
device. This is needed when ifname is unspecified in the command line and qemu
were asked to create tap device by itself. In this situation, the name were
allocated by kernel, so if multiqueue is asked, we need to fetch its name after
creating the first queue.

Only linux has this support since it's the only platform that supports
multiqueue tap.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
      e5dc0b40
    • Jason Wang's avatar
      tap: add Linux multiqueue support · 94fdc6d0
      Jason Wang authored 
      
This patch add basic multiqueue support for Linux. When multiqueue is needed, we
will first check whether kernel support multiqueue tap before creating more
queues. Two new functions tap_fd_enable() and tap_fd_disable() were introduced
to enable and disable a specific queue. Since the multiqueue is only supported
in Linux, return error on other platforms.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
      94fdc6d0
  21. Dec 19, 2012
    • Paolo Bonzini's avatar
      net: reorganize headers · 1422e32d
      Paolo Bonzini authored 
      
Move public headers to include/net, and leave private headers in net/.
Put the virtio headers in include/net/tap.h, removing the multiple copies
that existed.  Leave include/net/tap.h as the interface for NICs, and
net/tap_int.h as the interface for OS-specific parts of the tap backend.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      1422e32d
  23. Oct 08, 2012
    • Paolo Bonzini's avatar
      net: consolidate NetClientState header files into one · a245fc18
      Paolo Bonzini authored 
      
This patch doesn't seem much useful alone, I must admit.  However,
it makes sense as part of the upcoming directory reorganization,
where I want to have include/net/tap.h as the net<->hw interface
for tap.  Then having both net/tap.h and include/net/tap.h does
not work.  "Fixed" by moving all the init functions to a single
header file net/clients.h.

The patch also adopts a uniform style for including net/*.h files
from net/*.c, without the net/ path.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@gmail.com>
      a245fc18
  25. Aug 01, 2012
  27. Jul 23, 2012
    • Laszlo Ersek's avatar
      remove unused QemuOpts parameter from net init functions · 1a0c0958
      Laszlo Ersek authored 
      
v1->v2:
- unchanged

v2->v3:
- keep "qemu-option.h" included in "net/slirp.h"

Signed-off-by: default avatarLaszlo Ersek <lersek@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
      1a0c0958
    • Laszlo Ersek's avatar
      convert net_init_tap() to NetClientOptions · 08c573a8
      Laszlo Ersek authored 
      
Signed-off-by: default avatarLaszlo Ersek <lersek@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
      08c573a8
    • Laszlo Ersek's avatar
      convert net_client_init() to OptsVisitor · 6687b79d
      Laszlo Ersek authored 
      
The net_client_init() prototype is kept intact.

Based on "is_netdev", the QemuOpts-rooted QemuOpt-list is parsed as a
Netdev or a NetLegacy. The original meat of net_client_init() is moved to
and simplified in net_client_init1():

Fields not common between -net and -netdev are clearly separated. Getting
the name for the init functions is cleaner: Netdev::id is mandatory, and
all init functions handle a NULL NetLegacy::name. NetLegacy::vlan
explicitly depends on -net (see below).

Verifying the "type=" option for -netdev can be turned into a switch.

Format validation with qemu_opts_validate() can be removed because the
visitor covers it. Relatedly, the "net_client_types" array is reduced to
an array of init functions that can be directly indexed by opts->kind.
(Help text is available in the schema JSON.)

The outermost negation in the condition around qemu_find_vlan() was
flattened, because it expresses the dependent code's requirements more
clearly.

VLAN lookup is avoided if there's no init function to pass the VLAN to.

Whenever the value of type=... is needed, we substitute
NetClientOptionsKind_lookup[kind].

The individual init functions are not converted yet, thus the original
QemuOpts instance is passed transparently.

v1->v2:
- NetLegacy::name is optional. Tracked it through all init functions: they
  all handle a NULL name. Updated commit message accordingly.

v2->v3:
- NetLegacy::id is allowed and takes precedence over NetLegacy::name.

Signed-off-by: default avatarLaszlo Ersek <lersek@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
      6687b79d
  29. Jun 04, 2012
  31. Feb 01, 2012
    • Corey Bryant's avatar
      Add support for net bridge · a7c36ee4
      Corey Bryant authored 
      
The most common use of -net tap is to connect a tap device to a bridge.  This
requires the use of a script and running qemu as root in order to allocate a
tap device to pass to the script.

This model is great for portability and flexibility but it's incredibly
difficult to eliminate the need to run qemu as root.  The only really viable
mechanism is to use tunctl to create a tap device, attach it to a bridge as
root, and then hand that tap device to qemu.  The problem with this mechanism
is that it requires administrator intervention whenever a user wants to create
a guest.

By essentially writing a helper that implements the most common qemu-ifup
script that can be safely given cap_net_admin, we can dramatically simplify
things for non-privileged users.  We still support existing -net tap options
as a mechanism for advanced users and backwards compatibility.

Currently, this is very Linux centric but there's really no reason why it
couldn't be extended for other Unixes.

A typical invocation would be similar to one of the following:

  qemu linux.img -net bridge -net nic,model=virtio

  qemu linux.img -net tap,helper="/usr/local/libexec/qemu-bridge-helper"
                 -net nic,model=virtio

  qemu linux.img -netdev bridge,id=hn0
                 -device virtio-net-pci,netdev=hn0,id=nic1

  qemu linux.img -netdev tap,helper="/usr/local/libexec/qemu-bridge-helper",id=hn0
                 -device virtio-net-pci,netdev=hn0,id=nic1

The default bridge that we attach to is br0.  The thinking is that a distro
could preconfigure such an interface to allow out-of-the-box bridged networking.

Alternatively, if a user wants to use a different bridge, a typical invocation
would be simliar to one of the following:

  qemu linux.img -net bridge,br=qemubr0 -net nic,model=virtio

  qemu linux.img -net tap,helper="/usr/local/libexec/qemu-bridge-helper --br=qemubr0"
                 -net nic,model=virtio

  qemu linux.img -netdev bridge,br=qemubr0,id=hn0
                 -device virtio-net-pci,netdev=hn0,id=nic1

  qemu linux.img -netdev tap,helper="/usr/local/libexec/qemu-bridge-helper --br=qemubr0",id=hn0
                 -device virtio-net-pci,netdev=hn0,id=nic1

Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: default avatarRicha Marwaha <rmarwah@linux.vnet.ibm.com>
Signed-off-by: default avatarCorey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
      a7c36ee4
  33. Sep 07, 2010
  35. Apr 01, 2010
  37. Oct 30, 2009
  39. May 18, 2009
  41. Mar 03, 2009
  43. Apr 08, 2008
  45. Feb 01, 2008
  47. Oct 07, 2007
  49. Sep 16, 2007