add kernel interface manipulation utilities

pkg/kernel/link.go

@@ -0,0 +1,230 @@
+// Copyright (c) 2020 Intel Corporation. All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kernel
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+
+	"github.com/vishvananda/netlink"
+	"github.com/vishvananda/netns"
+)
+
+// State defines admin state of the network interface
+type State uint
+
+const (
+	// DOWN is link admin state down
+	DOWN State = iota
+	// UP is link admin state down
+	UP
+)
+
+// Link represents network interface and specifies operations
+// that can be performed on that interface.
+type Link interface {
+	AddAddress(ip string) error
+	DeleteAddress(ip string) error
+	MoveToNetns(target netns.NsHandle) error
+	SetAdminState(state State) error
+	SetName(name string) error
+}
+
+// link provides Link interface implementation
+type link struct {
+	link  netlink.Link
+	netns netns.NsHandle
+}
+
+func (l *link) MoveToNetns(target netns.NsHandle) error {
+	// don't do anything if already there
+	if l.netns.Equal(target) {
+		return nil
+	}
+
+	// set link down
+	err := l.SetAdminState(DOWN)
+	if err != nil {
+		return errors.Errorf("failed to move link %s to netns: %q", l.link, err)
+	}
+
+	// set netns
+	err = netlink.LinkSetNsFd(l.link, int(target))
+	if err != nil {
+		return errors.Errorf("failed to move link %s to netns: %q", l.link, err)
+	}
+
+	l.netns = target
+
+	return nil
+}
+
+func (l *link) AddAddress(ip string) error {
+	// parse IP address
+	addr, err := netlink.ParseAddr(ip)
+	if err != nil {
+		return errors.Errorf("failed to parse IP address %q: %s", ip, err)
+	}
+
+	// check if address is already assigned
+	current, err := netlink.AddrList(l.link, netlink.FAMILY_ALL)
+	if err != nil {
+		return errors.Errorf("failed to get current IP address list %q: %s", ip, err)
+	}
+
+	for _, existing := range current {
+		if addr.Equal(existing) {
+			// nothing to do
+			return nil
+		}
+	}
+
+	// add address
+	err = netlink.AddrAdd(l.link, addr)
+	if err != nil {
+		return errors.Errorf("failed to add IP address %q: %s", ip, err)
+	}
+
+	return nil
+}
+
+func (l *link) DeleteAddress(ip string) error {
+	// parse IP address
+	addr, err := netlink.ParseAddr(ip)
+	if err != nil {
+		return errors.Errorf("failed to parse IP address %q: %s", ip, err)
+	}
+
+	// delete address
+	err = netlink.AddrDel(l.link, addr)
+	if err != nil {
+		return errors.Errorf("failed to delete IP address %q: %s", ip, err)
+	}
+
+	return nil
+}
+
+func (l *link) SetAdminState(state State) error {
+	switch state {
+	case DOWN:
+		err := netlink.LinkSetDown(l.link)
+		if err != nil {
+			return errors.Errorf("failed to set %s down: %s", l.link, err)
+		}
+	case UP:
+		err := netlink.LinkSetUp(l.link)
+		if err != nil {
+			return errors.Errorf("failed to bring %s up: %s", l.link, err)
+		}
+	}
+
+	return nil
+}
+
+func (l *link) SetName(name string) error {
+	if l.link.Attrs().Name != name {
+		err := netlink.LinkSetName(l.link, name)
+		if err != nil {
+			return errors.Errorf("failed to set interface name to %s: %s", name, err)
+		}
+	}
+
+	return nil
+}
+
+// FindHostDevice returns a new instance of link representing host device, based on the PCI
+// address and/or target interface name.
+func FindHostDevice(pciAddress, name string, namespaces ...netns.NsHandle) (Link, error) {
+	// TODO: add support for shared l interfaces (like Mellanox NICs)
+
+	attempts := []func(netns.NsHandle, string, string) (netlink.Link, error){
+		searchByPCIAddress,
+		searchByName,
+	}
+
+	// search for link with a matching name or PCI address in the provided namespaces
+	for _, ns := range namespaces {
+		for _, search := range attempts {
+			found, err := search(ns, name, pciAddress)
+			if err != nil {
+				continue
+			}
+
+			if found != nil {
+				return &link{
+					link:  found,
+					netns: ns,
+				}, nil
+			}
+		}
+	}
+
+	return nil, errors.Errorf("failed to obtain netlink link matching criteria: name=%s or pciAddress=%s", name, pciAddress)
+}
+
+func searchByPCIAddress(ns netns.NsHandle, name, pciAddress string) (netlink.Link, error) {
+	// execute in context of the pod's namespace
+	err := netns.Set(ns)
+	if err != nil {
+		return nil, errors.Errorf("failed to enter namespace: %s", err)
+	}
+
+	netDir := filepath.Join("/sys/bus/pci/devices", pciAddress, "net")
+	if _, err := os.Lstat(netDir); err != nil {
+		return nil, errors.Errorf("no net directory under pci device %s: %q", pciAddress, err)
+	}
+
+	fInfos, err := ioutil.ReadDir(netDir)
+	if err != nil {
+		return nil, errors.Errorf("failed to read net directory %s: %q", netDir, err)
+	}
+
+	names := make([]string, 0)
+	for _, f := range fInfos {
+		names = append(names, f.Name())
+	}
+
+	if len(names) == 0 {
+		return nil, errors.Errorf("no links with PCI address %s found", pciAddress)
+	}
+
+	link, err := netlink.LinkByName(names[0])
+	if err != nil {
+		return nil, errors.Errorf("error getting host device with PCI address %s", pciAddress)
+	}
+
+	return link, nil
+}
+
+func searchByName(ns netns.NsHandle, name, pciAddress string) (netlink.Link, error) {
+	// execute in context of the pod's namespace
+	err := netns.Set(ns)
+	if err != nil {
+		return nil, errors.Errorf("failed to switch to namespace: %s", err)
+	}
+
+	// get link
+	link, err := netlink.LinkByName(name)
+	if err != nil {
+		return nil, errors.Errorf("failed to get link with name %s", name)
+	}
+
+	return link, nil
+}