mirror of
https://github.com/netbirdio/gvisor.git
synced 2026-05-22 17:12:49 -07:00
Nicolas Lacasse
ebda75f504
Previously we were initializing these at startup and they could never change. Now they are read dynamically every time they are requested. This is a pre-requisite for implementing methods that mutate the interfaces (stack.AddInterface()). PiperOrigin-RevId: 522109098
104 lines
3.4 KiB
Go
104 lines
3.4 KiB
Go
// Copyright 2021 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package hostinet
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import (
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"runtime"
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"unsafe"
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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/hostarch"
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"gvisor.dev/gvisor/pkg/sentry/inet"
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)
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func queryInterfaceFeatures(interfaces map[int32]inet.Interface) error {
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fd, err := queryFD()
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if err != nil {
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return err
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}
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defer unix.Close(fd)
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for idx, nic := range interfaces {
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var ifr linux.IFReq
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copy(ifr.IFName[:], nic.Name)
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var gfeatures linux.EthtoolGFeatures
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// Each feature block is sufficient to query 32 features, the linux
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// kernel today supports upto 64 features per device. Technically it
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// can support more in the future but this is sufficient for our use
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// right now.
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const (
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numFeatureBlocks = 2
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ifrDataSz = unsafe.Sizeof(linux.EthtoolGFeatures{}) + numFeatureBlocks*unsafe.Sizeof(linux.EthtoolGetFeaturesBlock{})
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)
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featureBlocks := make([]linux.EthtoolGetFeaturesBlock, numFeatureBlocks)
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b := make([]byte, ifrDataSz)
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gfeatures.Cmd = uint32(linux.ETHTOOL_GFEATURES)
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gfeatures.Size = numFeatureBlocks
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gfeatures.MarshalBytes(b)
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next := b[unsafe.Sizeof(linux.EthtoolGFeatures{}):]
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for i := 0; i < numFeatureBlocks; i++ {
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featureBlocks[i].MarshalBytes(next)
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next = next[unsafe.Sizeof(linux.EthtoolGetFeaturesBlock{}):]
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}
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// Technically the next two lines are not safe as Go GC can technically move
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// b to a new location and the pointer value stored in ifr.Data could point
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// to random memory. But the reality today is that Go GC is not a moving GC
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// so this is essentially safe as of today.
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//
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// TODO(b/209014118): Use Pin API when available in Go runtime to make this
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// safe.
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dataPtr := unsafe.Pointer(&b[0])
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hostarch.ByteOrder.PutUint64(ifr.Data[:8], uint64(uintptr(dataPtr)))
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if _, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), unix.SIOCETHTOOL, uintptr(unsafe.Pointer(&ifr))); errno != 0 {
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return errno
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}
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// Unmarshall the features back.
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gfeatures.UnmarshalBytes(b)
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next = b[unsafe.Sizeof(linux.EthtoolGFeatures{}):]
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for i := 0; i < int(gfeatures.Size); i++ {
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featureBlocks[i].UnmarshalBytes(next)
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next = next[unsafe.Sizeof(linux.EthtoolGetFeaturesBlock{}):]
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}
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// Store the queried features.
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iface := interfaces[idx]
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iface.Features = make([]linux.EthtoolGetFeaturesBlock, gfeatures.Size)
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copy(iface.Features, featureBlocks)
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interfaces[idx] = iface
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// This ensures b is not garbage collected before this point to ensure that
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// the slice is not collected before the syscall returns and we copy out the
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// data.
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runtime.KeepAlive(b)
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}
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return nil
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}
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func queryFD() (int, error) {
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// Try both AF_INET and AF_INET6 in case only one is supported.
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var fd int
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var err error
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for _, family := range []int{unix.AF_INET6, unix.AF_INET} {
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fd, err = unix.Socket(family, unix.SOCK_STREAM, 0)
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if err == nil {
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return fd, err
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}
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}
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return fd, err
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}
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