torvalds/linux@e269d79c7d broke virtio_net
TCP & UDP GRO causing GRO writes to return EINVAL. The bug was then
resolved later in
torvalds/linux@89add40066. The offending
commit was pulled into various LTS releases.
Updates tailscale/tailscale#13041
Signed-off-by: Jordan Whited <jordan@tailscale.com>
When generating page-aligned random bytes, random data started at the
beginning of the buffer that will be chopped off. When the page size
differs, the start of the returned slice is different than expected for
the expected checksums, causing the tests to fail.
External implementers of tun.Device may support GSO, and may also be
platform-agnostic, e.g. gVisor.
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Certain device drivers (e.g. vxlan, geneve) do not properly handle
coalesced UDP packets later in the stack, resulting in packet loss.
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Close closes the events channel, resulting in a panic from send on
closed channel.
Reported-By: Brad Fitzpatrick <brad@tailscale.com>
Link: https://github.com/tailscale/tailscale/issues/9555
Signed-off-by: James Tucker <james@tailscale.com>
This adds AMD64 assembly implementations of IP checksum computation, one
for baseline AMD64 and the other for v3 AMD64 (AVX2 and BMI2).
All performance numbers reported are from a Ryzen 7 4750U but similar
improvements are expected for a wide range of processors.
The generic IP checksum implementation has also been further improved to
be significantly faster using bits.AddUint64 (for a 64KiB buffer the
throughput improves from 15,000MiB/s to 27,600MiB/s; similar gains are
also reported on ARM64 but I do not have specific numbers).
The baseline AMD64 implementation for a 64KiB buffer reports 32,700MiB/s
and the AVX2 implementation is slightly over 107,000MiB/s.
Unfortunately, for very small sizes (e.g. the expected size for an IPv4
header) setting up SIMD computation involves some overhead that makes
computing a checksum for small buffers slower than a non-SIMD
implementation. Even more unfortunately, testing for this at runtimen in
Go and calling a func optimized for small buffers mitigates most of the
improvement due to call overhead. The break even point is around 256
byte buffers; IPv4 headers are no more than 60 bytes including
extensions. IPv6 headers do not have a checksum but are a fixed size of
40 bytes. As a result, the generated assembly code uses an alternate
approach for buffers of less than 256 bytes. Additionally, buffers of
less than 32 bytes need to be handled specially because the strategy for
reading buffers that are not a multiple of 8 bytes fails when the buffer
is too small.
As suggested by additional benchmarking, pseudo header computation has
been rewritten to be faster (benchmark time reduced by 1/2 to 1/4).
Updates tailscale/corp#9755
Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
IPv4 header and pseudo header checksums were being computed on every
merge operation. Additionally, virtioNetHdr was being written at the
same time. This delays those operations until after all coalescing has
occurred.
Reviewed-by: Adrian Dewhurst <adrian@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
tcpGRO() was using an incorrect IPv4 more fragments bit mask.
tcpPacketsCanCoalesce() was not distinguishing tcp6 from tcp4, and TTL
values were not compared. TTL values should be equal at the IP layer,
otherwise the packets should not coalesce. This tracks with the kernel.
Reviewed-by: Denton Gentry <dgentry@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
IP options were not being compared prior to coalescing. They are not
commonly used. Disqualification due to nonzero options is in line with
the kernel.
Reviewed-by: Denton Gentry <dgentry@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Enable TCP SACK for the gVisor Stack used in tun/netstack. This can
improve throughput by an order of magnitude in the presence of packet
loss.
Reviewed-by: James Tucker <james@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
There's not really a use at the moment for making this configurable, and
once bind_windows.go behaves like bind_std.go, we'll be able to use
constants everywhere. So begin that simplification now.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Implement TCP offloading via TSO and GRO for the Linux tun.Device, which
is made possible by virtio extensions in the kernel's TUN driver.
Delete conn.LinuxSocketEndpoint in favor of a collapsed conn.StdNetBind.
conn.StdNetBind makes use of recvmmsg() and sendmmsg() on Linux. All
platforms now fall under conn.StdNetBind, except for Windows, which
remains in conn.WinRingBind, which still needs to be adjusted to handle
multiple packets.
Also refactor sticky sockets support to eventually be applicable on
platforms other than just Linux. However Linux remains the sole platform
that fully implements it for now.
Co-authored-by: James Tucker <james@tailscale.com>
Signed-off-by: James Tucker <james@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Accept packet vectors for reading and writing in the tun.Device and
conn.Bind interfaces, so that the internal plumbing between these
interfaces now passes a vector of packets. Vectors move untouched
between these interfaces, i.e. if 128 packets are received from
conn.Bind.Read(), 128 packets are passed to tun.Device.Write(). There is
no internal buffering.
Currently, existing implementations are only adjusted to have vectors
of length one. Subsequent patches will improve that.
Also, as a related fixup, use the unix and windows packages rather than
the syscall package when possible.
Co-authored-by: James Tucker <james@tailscale.com>
Signed-off-by: James Tucker <james@tailscale.com>
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This seems like a much better demonstration as it removes the need for
external components.
Signed-off-by: Søren L. Hansen <sorenisanerd@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
To build with go1.19, gvisor needs
99325baf ("Bump gVisor build tags to go1.19").
However gvisor.dev/gvisor/pkg/tcpip/buffer is no longer available,
so refactor to use gvisor.dev/gvisor/pkg/tcpip/link/channel directly.
Signed-off-by: Shengjing Zhu <i@zhsj.me>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Use unix.ByteSliceToString in (*NativeTun).nameSlice to convert the
TUNGETIFF ioctl result []byte to a string.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Alexander Neumann <alexander.neumann@redteam-pentesting.de>
[Jason: don't wrap deadline error.]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit fixes all callsites of netip.AddrFromSlice(), which has
changed its signature and now returns two values.
Signed-off-by: Alexander Neumann <alexander.neumann@redteam-pentesting.de>
[Jason: remove error handling from AddrFromSlice.]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Provide a PacketConn interface for netstack's ICMP endpoint; netstack
currently only provides EchoRequest/EchoResponse ICMP support, so this
code exposes only an interface for doing ping.
Signed-off-by: Thomas Ptacek <thomas@sockpuppet.org>
[Jason: rework structure, match std go interfaces, add example code]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
There are more places where we'll need to add it later, when Go 1.18
comes out with support for it in the "net" package. Also, allowedips
still uses slices internally, which might be suboptimal.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
