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2020-07-15net: detect errors from probing vnet hdr flag for TAP devicesDaniel P. Berrange
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: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Tested-by: Dr. 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: Laurent Vivier <lvivier@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
2019-06-12Include qemu-common.h exactly where neededMarkus Armbruster
No header includes qemu-common.h after this commit, as prescribed by qemu-common.h's file comment. Signed-off-by: Markus 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]
2018-03-02Include less of the generated modular QAPI headersMarkus Armbruster
In my "build everything" tree, a change to the types in qapi-schema.json triggers a recompile of about 4800 out of 5100 objects. The previous commit split up qmp-commands.h, qmp-event.h, qmp-visit.h, qapi-types.h. Each of these headers still includes all its shards. Reduce compile time by including just the shards we actually need. To illustrate the benefits: adding a type to qapi/migration.json now recompiles some 2300 instead of 4800 objects. The next commit will improve it further. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20180211093607.27351-24-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> [eblake: rebase to master] Signed-off-by: Eric Blake <eblake@redhat.com>
2016-07-12Clean up header guards that don't match their file nameMarkus Armbruster
Header guard symbols should match their file name to make guard collisions less likely. Offenders found with scripts/clean-header-guards.pl -vn. Cleaned up with scripts/clean-header-guards.pl, followed by some renaming of new guard symbols picked by the script to better ones. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net>
2015-06-17tap: add VNET_LE/VNET_BE operationsGreg Kurz
The linux tap and macvtap backends can be told to parse vnet headers according to little or big endian. This is done through the TUNSETVNETLE and TUNSETVNETBE ioctls. This patch brings all the plumbing for QEMU to use these APIs. Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2015-05-27tap: Permit incremental conversion of tap_open() to ErrorMarkus Armbruster
Convert the trivial ones immediately: tap-aix and tap-haiku. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-id: 1431691143-1015-11-git-send-email-armbru@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-05-27tap: Convert tap_set_sndbuf() to ErrorMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-id: 1431691143-1015-8-git-send-email-armbru@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-11-02tap_int.h: remove repeating NETWORK_SCRIPT definesGonglei
DEFAULT_NETWORK_SCRIPT and DEFAULT_NETWORK_DOWN_SCRIPT have been defined in net/net.h included in tap.c, which is the only C file that using those two macro. Let's remove the repeating macroinstruction. Signed-off-by: Gonglei <arei.gonglei@huawei.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2013-02-01tap: multiqueue supportJason Wang
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: Jason Wang <jasowang@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-02-01tap: introduce a helper to get the name of an interfaceJason Wang
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: Jason Wang <jasowang@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-02-01tap: add Linux multiqueue supportJason Wang
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: Jason Wang <jasowang@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-12-19net: reorganize headersPaolo Bonzini
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: Paolo Bonzini <pbonzini@redhat.com>