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Pull request: dhcpd: do not assume mac addrs of 6 bytes

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Closes #2828.

Squashed commit of the following:

commit 26c6cf81c32469e1c4955aafb40490c29b4d1a99
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Mar 30 17:43:53 2021 +0300

    dhcpd: do not assume mac addrs of 6 bytes
This commit is contained in:
Ainar Garipov 2021-03-31 12:36:57 +03:00
parent 48e82f9ab5
commit bfc7e16d84
7 changed files with 204 additions and 48 deletions
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2
CHANGELOG.md
View File

@ -33,6 +33,7 @@ and this project adheres to
### Fixed
- Assumption that MAC addresses always have the length of 6 octets ([#2828]).
- Support for more than one `/24` subnet in DHCP ([#2541]).
- Invalid filenames in the `mobileconfig` API responses ([#2835]).
@ -47,6 +48,7 @@ and this project adheres to
[#2498]: https://github.com/AdguardTeam/AdGuardHome/issues/2498
[#2533]: https://github.com/AdguardTeam/AdGuardHome/issues/2533
[#2541]: https://github.com/AdguardTeam/AdGuardHome/issues/2541
[#2828]: https://github.com/AdguardTeam/AdGuardHome/issues/2828
[#2835]: https://github.com/AdguardTeam/AdGuardHome/issues/2835
[#2838]: https://github.com/AdguardTeam/AdGuardHome/issues/2838

23
internal/aghnet/addr.go Normal file
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@ -0,0 +1,23 @@
package aghnet
import (
"fmt"
"net"
"github.com/AdguardTeam/AdGuardHome/internal/agherr"
)
// ValidateHardwareAddress returns an error if hwa is not a valid EUI-48,
// EUI-64, or 20-octet InfiniBand link-layer address.
func ValidateHardwareAddress(hwa net.HardwareAddr) (err error) {
defer agherr.Annotate("validating hardware address %q: %w", &err, hwa)
switch l := len(hwa); l {
case 0:
return agherr.Error("address is empty")
case 6, 8, 20:
return nil
default:
return fmt.Errorf("bad len: %d", l)
}
}

57
internal/aghnet/addr_test.go Normal file
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@ -0,0 +1,57 @@
package aghnet
import (
"net"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestValidateHardwareAddress(t *testing.T) {
testCases := []struct {
name string
wantErrMsg string
in net.HardwareAddr
}{{
name: "success_eui_48",
wantErrMsg: "",
in: net.HardwareAddr{0x00, 0x01, 0x02, 0x03, 0x04, 0x05},
}, {
name: "success_eui_64",
wantErrMsg: "",
in: net.HardwareAddr{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07},
}, {
name: "success_infiniband",
wantErrMsg: "",
in: net.HardwareAddr{
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13,
},
}, {
name: "error_nil",
wantErrMsg: `validating hardware address "": address is empty`,
in: nil,
}, {
name: "error_empty",
wantErrMsg: `validating hardware address "": address is empty`,
in: net.HardwareAddr{},
}, {
name: "error_bad",
wantErrMsg: `validating hardware address "00:01:02:03": bad len: 4`,
in: net.HardwareAddr{0x00, 0x01, 0x02, 0x03},
}}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
err := ValidateHardwareAddress(tc.in)
if tc.wantErrMsg == "" {
assert.NoError(t, err)
} else {
require.Error(t, err)
assert.Equal(t, tc.wantErrMsg, err.Error())
}
})
}
}

58
internal/dhcpd/routeradv.go
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@ -7,6 +7,7 @@ import (
"sync/atomic"
"time"
"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
"github.com/AdguardTeam/golibs/log"
"golang.org/x/net/icmp"
"golang.org/x/net/ipv6"
@ -36,6 +37,33 @@ type icmpv6RA struct {
mtu uint32
}
// hwAddrToLinkLayerAddr converts a hardware address into a form required by
// RFC4861. That is, a byte slice of length divisible by 8.
//
// See https://tools.ietf.org/html/rfc4861#section-4.6.1.
func hwAddrToLinkLayerAddr(hwa net.HardwareAddr) (lla []byte, err error) {
err = aghnet.ValidateHardwareAddress(hwa)
if err != nil {
// Don't wrap the error, because it already contains enough
// context.
return nil, err
}
if len(hwa) == 6 || len(hwa) == 8 {
lla = make([]byte, 8)
copy(lla, hwa)
return lla, nil
}
// Assume that aghnet.ValidateHardwareAddress prevents lengths other
// than 20 by now.
lla = make([]byte, 24)
copy(lla, hwa)
return lla, nil
}
// Create an ICMPv6.RouterAdvertisement packet with all necessary options.
//
// ICMPv6:
@ -63,15 +91,23 @@ type icmpv6RA struct {
// Reserved[2]
// MTU[4]
// Option=Source link-layer address(1):
// Link-Layer Address[6]
// Link-Layer Address[8/24]
// Option=Recursive DNS Server(25):
// Type[1]
// Length * 8bytes[1]
// Reserved[2]
// Lifetime[4]
// Addresses of IPv6 Recursive DNS Servers[16]
func createICMPv6RAPacket(params icmpv6RA) []byte {
data := make([]byte, 88)
func createICMPv6RAPacket(params icmpv6RA) (data []byte, err error) {
var lla []byte
lla, err = hwAddrToLinkLayerAddr(params.sourceLinkLayerAddress)
if err != nil {
return nil, fmt.Errorf("converting source link layer address: %w", err)
}
// TODO(a.garipov): Don't use a magic constant here. Refactor the code
// and make all constants named instead of all those comments..
data = make([]byte, 82+len(lla))
i := 0
// ICMPv6:
@ -138,8 +174,9 @@ func createICMPv6RAPacket(params icmpv6RA) []byte {
data[i] = 1 // Type
data[i+1] = 1 // Length
i += 2
copy(data[i:], params.sourceLinkLayerAddress) // Link-Layer Address[6]
i += 6
copy(data[i:], lla) // Link-Layer Address[8/24]
i += len(lla)
// Option=Recursive DNS Server:
@ -152,11 +189,11 @@ func createICMPv6RAPacket(params icmpv6RA) []byte {
i += 4
copy(data[i:], params.recursiveDNSServer) // Addresses of IPv6 Recursive DNS Servers[16]
return data
return data, nil
}
// Init - initialize RA module
func (ra *raCtx) Init() error {
func (ra *raCtx) Init() (err error) {
ra.stop.Store(0)
ra.conn = nil
if !(ra.raAllowSLAAC || ra.raSLAACOnly) {
@ -177,9 +214,12 @@ func (ra *raCtx) Init() error {
params.prefix = make([]byte, 16)
copy(params.prefix, ra.prefixIPAddr[:8]) // /64
data := createICMPv6RAPacket(params)
var data []byte
data, err = createICMPv6RAPacket(params)
if err != nil {
return fmt.Errorf("creating packet: %w", err)
}
var err error
success := false
ipAndScope := ra.ipAddr.String() + "%" + ra.ifaceName
ra.conn, err = icmp.ListenPacket("ip6:ipv6-icmp", ipAndScope)

31
internal/dhcpd/routeradv_test.go
View File

@ -7,8 +7,23 @@ import (
"github.com/stretchr/testify/assert"
)
func TestRA(t *testing.T) {
data := createICMPv6RAPacket(icmpv6RA{
func TestCreateICMPv6RAPacket(t *testing.T) {
wantData := []byte{
0x86, 0x00, 0x00, 0x00, 0x40, 0x40, 0x07, 0x08,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x03, 0x04, 0x40, 0xc0, 0x00, 0x00, 0x0e, 0x10,
0x00, 0x00, 0x0e, 0x10, 0x00, 0x00, 0x00, 0x00,
0x12, 0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x05, 0x01, 0x00, 0x00, 0x00, 0x00, 0x05, 0xdc,
0x01, 0x01, 0x0a, 0x00, 0x27, 0x00, 0x00, 0x00,
0x00, 0x00, 0x19, 0x03, 0x00, 0x00, 0x00, 0x00,
0x0e, 0x10, 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x08, 0x00, 0x27, 0xff, 0xfe, 0x00,
0x00, 0x00,
}
gotData, err := createICMPv6RAPacket(icmpv6RA{
managedAddressConfiguration: false,
otherConfiguration: true,
mtu: 1500,
@ -17,13 +32,7 @@ func TestRA(t *testing.T) {
recursiveDNSServer: net.ParseIP("fe80::800:27ff:fe00:0"),
sourceLinkLayerAddress: []byte{0x0a, 0x00, 0x27, 0x00, 0x00, 0x00},
})
dataCorrect := []byte{
0x86, 0x00, 0x00, 0x00, 0x40, 0x40, 0x07, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x03, 0x04, 0x40, 0xc0, 0x00, 0x00, 0x0e, 0x10, 0x00, 0x00, 0x0e, 0x10, 0x00, 0x00, 0x00, 0x00,
0x12, 0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x05, 0x01, 0x00, 0x00, 0x00, 0x00, 0x05, 0xdc, 0x01, 0x01, 0x0a, 0x00, 0x27, 0x00, 0x00, 0x00,
0x19, 0x03, 0x00, 0x00, 0x00, 0x00, 0x0e, 0x10, 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x08, 0x00, 0x27, 0xff, 0xfe, 0x00, 0x00, 0x00,
}
assert.Equal(t, dataCorrect, data)
assert.NoError(t, err)
assert.Equal(t, wantData, gotData)
}

26
internal/dhcpd/v4.go
View File

@ -10,6 +10,7 @@ import (
"time"
"github.com/AdguardTeam/AdGuardHome/internal/agherr"
"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
"github.com/AdguardTeam/golibs/log"
"github.com/go-ping/ping"
"github.com/insomniacslk/dhcp/dhcpv4"
@ -289,8 +290,9 @@ func (s *v4Server) AddStaticLease(l Lease) (err error) {
return fmt.Errorf("invalid ip %q, only ipv4 is supported", l.IP)
}
if len(l.HWAddr) != 6 {
return fmt.Errorf("invalid mac %q, only EUI-48 is supported", l.HWAddr)
err = aghnet.ValidateHardwareAddress(l.HWAddr)
if err != nil {
return fmt.Errorf("validating lease: %w", err)
}
l.Expiry = time.Unix(leaseExpireStatic, 0)
@ -330,17 +332,21 @@ func (s *v4Server) AddStaticLease(l Lease) (err error) {
return nil
}
// RemoveStaticLease removes a static lease (thread-safe)
func (s *v4Server) RemoveStaticLease(l Lease) error {
// RemoveStaticLease removes a static lease. It is safe for concurrent use.
func (s *v4Server) RemoveStaticLease(l Lease) (err error) {
defer agherr.Annotate("dhcpv4: %w", &err)
if len(l.IP) != 4 {
return fmt.Errorf("invalid IP")
}
if len(l.HWAddr) != 6 {
return fmt.Errorf("invalid MAC")
err = aghnet.ValidateHardwareAddress(l.HWAddr)
if err != nil {
return fmt.Errorf("validating lease: %w", err)
}
s.leasesLock.Lock()
err := s.rmLease(l)
err = s.rmLease(l)
if err != nil {
s.leasesLock.Unlock()
@ -688,8 +694,10 @@ func (s *v4Server) packetHandler(conn net.PacketConn, peer net.Addr, req *dhcpv4
return
}
if len(req.ClientHWAddr) != 6 {
log.Debug("dhcpv4: Invalid ClientHWAddr")
err = aghnet.ValidateHardwareAddress(req.ClientHWAddr)
if err != nil {
log.Error("dhcpv4: invalid ClientHWAddr: %s", err)
return
}

55
internal/dhcpd/v6.go
View File

@ -9,6 +9,8 @@ import (
"sync"
"time"
"github.com/AdguardTeam/AdGuardHome/internal/agherr"
"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
"github.com/AdguardTeam/golibs/log"
"github.com/insomniacslk/dhcp/dhcpv6"
"github.com/insomniacslk/dhcp/dhcpv6/server6"
@ -158,19 +160,23 @@ func (s *v6Server) rmDynamicLease(lease Lease) error {
return nil
}
// AddStaticLease - add a static lease
func (s *v6Server) AddStaticLease(l Lease) error {
// AddStaticLease adds a static lease. It is safe for concurrent use.
func (s *v6Server) AddStaticLease(l Lease) (err error) {
defer agherr.Annotate("dhcpv6: %w", &err)
if len(l.IP) != 16 {
return fmt.Errorf("invalid IP")
}
if len(l.HWAddr) != 6 {
return fmt.Errorf("invalid MAC")
err = aghnet.ValidateHardwareAddress(l.HWAddr)
if err != nil {
return fmt.Errorf("validating lease: %w", err)
}
l.Expiry = time.Unix(leaseExpireStatic, 0)
s.leasesLock.Lock()
err := s.rmDynamicLease(l)
err = s.rmDynamicLease(l)
if err != nil {
s.leasesLock.Unlock()
return err
@ -183,17 +189,21 @@ func (s *v6Server) AddStaticLease(l Lease) error {
return nil
}
// RemoveStaticLease - remove a static lease
func (s *v6Server) RemoveStaticLease(l Lease) error {
// RemoveStaticLease removes a static lease. It is safe for concurrent use.
func (s *v6Server) RemoveStaticLease(l Lease) (err error) {
defer agherr.Annotate("dhcpv6: %w", &err)
if len(l.IP) != 16 {
return fmt.Errorf("invalid IP")
}
if len(l.HWAddr) != 6 {
return fmt.Errorf("invalid MAC")
err = aghnet.ValidateHardwareAddress(l.HWAddr)
if err != nil {
return fmt.Errorf("validating lease: %w", err)
}
s.leasesLock.Lock()
err := s.rmLease(l)
err = s.rmLease(l)
if err != nil {
s.leasesLock.Unlock()
return err
@ -271,8 +281,10 @@ func (s *v6Server) findFreeIP() net.IP {
// Reserve lease for MAC
func (s *v6Server) reserveLease(mac net.HardwareAddr) *Lease {
l := Lease{}
l.HWAddr = make([]byte, 6)
l := Lease{
HWAddr: make([]byte, len(mac)),
}
copy(l.HWAddr, mac)
s.leasesLock.Lock()
@ -564,7 +576,9 @@ func (s *v6Server) initRA(iface *net.Interface) error {
}
// Start starts the IPv6 DHCP server.
func (s *v6Server) Start() error {
func (s *v6Server) Start() (err error) {
defer agherr.Annotate("dhcpv6: %w", &err)
if !s.conf.Enabled {
return nil
}
@ -572,14 +586,14 @@ func (s *v6Server) Start() error {
ifaceName := s.conf.InterfaceName
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
return fmt.Errorf("dhcpv6: finding interface %s by name: %w", ifaceName, err)
return fmt.Errorf("finding interface %s by name: %w", ifaceName, err)
}
log.Debug("dhcpv6: starting...")
dnsIPAddrs, err := ifaceDNSIPAddrs(iface, ipVersion6, defaultMaxAttempts, defaultBackoff)
if err != nil {
return fmt.Errorf("dhcpv6: interface %s: %w", ifaceName, err)
return fmt.Errorf("interface %s: %w", ifaceName, err)
}
if len(dnsIPAddrs) == 0 {
@ -596,15 +610,18 @@ func (s *v6Server) Start() error {
// don't initialize DHCPv6 server if we must force the clients to use SLAAC
if s.conf.RASLAACOnly {
log.Debug("DHCPv6: not starting DHCPv6 server due to ra_slaac_only=true")
log.Debug("not starting dhcpv6 server due to ra_slaac_only=true")
return nil
}
log.Debug("dhcpv6: listening...")
if len(iface.HardwareAddr) != 6 {
return fmt.Errorf("dhcpv6: invalid MAC %s", iface.HardwareAddr)
err = aghnet.ValidateHardwareAddress(iface.HardwareAddr)
if err != nil {
return fmt.Errorf("validating interface %s: %w", iface.Name, err)
}
s.sid = dhcpv6.Duid{
Type: dhcpv6.DUID_LLT,
HwType: iana.HWTypeEthernet,
@ -623,7 +640,7 @@ func (s *v6Server) Start() error {
go func() {
err = s.srv.Serve()
log.Debug("DHCPv6: srv.Serve: %s", err)
log.Error("dhcpv6: srv.Serve: %s", err)
}()
return nil