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Support ranges in nftables #85

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Support ranges in nftables #85

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969439d
Fix IPv6 and timeout bug in nftables.
sbs2001 Oct 5, 2021
93bd0ea
Support ranges in nftables
sbs2001 Oct 6, 2021
cd21e91
Error out when NewIP is given bad size
sbs2001 Oct 6, 2021
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150 changes: 120 additions & 30 deletions nftables.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,29 +3,30 @@
package main

import (
"fmt"
"net"
"strings"
"time"

"github.com/crowdsecurity/crowdsec/pkg/models"
"github.com/google/nftables"
"github.com/google/nftables/expr"
"golang.org/x/sys/unix"
log "github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)

const defaultTimeout = 4 * time.Hour

type nft struct {
conn *nftables.Conn
conn6 *nftables.Conn
set *nftables.Set
set6 *nftables.Set
table *nftables.Table
table6 *nftables.Table
DenyAction string
DenyLog bool
DenyLogPrefix string
conn *nftables.Conn
conn6 *nftables.Conn
set *nftables.Set
set6 *nftables.Set
table *nftables.Table
table6 *nftables.Table
DenyAction string
DenyLog bool
DenyLogPrefix string
BlacklistsIpv4 string
BlacklistsIpv6 string
}
Expand Down Expand Up @@ -61,9 +62,11 @@ func (n *nft) Init() error {
Priority: nftables.ChainPriorityFilter,
})
set := &nftables.Set{
Name: n.BlacklistsIpv4,
Table: n.table,
KeyType: nftables.TypeIPAddr,
Name: n.BlacklistsIpv4,
Table: n.table,
KeyType: nftables.TypeIPAddr,
HasTimeout: true,
Interval: true,
}

if err := n.conn.AddSet(set, []nftables.SetElement{}); err != nil {
Expand Down Expand Up @@ -129,9 +132,11 @@ func (n *nft) Init() error {
Priority: nftables.ChainPriorityFilter,
})
set := &nftables.Set{
Name: n.BlacklistsIpv6,
Table: n.table6,
KeyType: nftables.TypeIP6Addr,
Name: n.BlacklistsIpv6,
Table: n.table6,
KeyType: nftables.TypeIP6Addr,
HasTimeout: true,
Interval: true,
}

if err := n.conn6.AddSet(set, []nftables.SetElement{}); err != nil {
Expand Down Expand Up @@ -192,9 +197,23 @@ func (n *nft) Add(decision *models.Decision) error {
log.Errorf("unable to parse timeout '%s' for '%s' : %s", *decision.Duration, *decision.Value, err)
timeout = defaultTimeout
}
var cidr string
if strings.Contains(*decision.Value, ":") { // ipv6
if n.conn6 != nil {
if err := n.conn.SetAddElements(n.set6, []nftables.SetElement{{Key: []byte(net.ParseIP(*decision.Value).To16()), Timeout: timeout}}); err != nil {
if !strings.Contains(*decision.Value, "/") {
cidr = fmt.Sprintf("%s/128", *decision.Value)
} else {
cidr = *decision.Value
}
_, cidrNet, err := net.ParseCIDR(cidr)
if err != nil {
return err
}
if err := n.conn6.SetAddElements(n.set6,
[]nftables.SetElement{
{Key: []byte(cidrNet.IP.To16()), Timeout: timeout},
{Key: []byte(incrementIP(BroadcastAddr(cidrNet)).To16()), IntervalEnd: true},
}); err != nil {
return err
}
if err := n.conn6.Flush(); err != nil {
Expand All @@ -205,13 +224,20 @@ func (n *nft) Add(decision *models.Decision) error {
return nil
}
} else { // ipv4
var ipAddr string
if strings.Contains(*decision.Value, "/") {
ipAddr = strings.Split(*decision.Value, "/")[0]
if !strings.Contains(*decision.Value, "/") {
cidr = fmt.Sprintf("%s/32", *decision.Value)
} else {
ipAddr = *decision.Value
cidr = *decision.Value
}
_, cidrNet, err := net.ParseCIDR(cidr)
if err != nil {
return err
}
if err := n.conn.SetAddElements(n.set, []nftables.SetElement{{Key: []byte(net.ParseIP(ipAddr).To4())}}); err != nil {
if err := n.conn.SetAddElements(n.set,
[]nftables.SetElement{
{Key: cidrNet.IP, Timeout: timeout},
{Key: incrementIP(BroadcastAddr(cidrNet)), IntervalEnd: true},
}); err != nil {
return err
}
if err := n.conn.Flush(); err != nil {
Expand All @@ -223,26 +249,49 @@ func (n *nft) Add(decision *models.Decision) error {
}

func (n *nft) Delete(decision *models.Decision) error {
var cidr string
if strings.Contains(*decision.Value, ":") { // ipv6
if n.conn6 != nil {
if err := n.conn.SetDeleteElements(n.set, []nftables.SetElement{{Key: net.ParseIP(*decision.Value).To16()}}); err != nil {
if !strings.Contains(*decision.Value, "/") {
cidr = fmt.Sprintf("%s/128", *decision.Value)
} else {
cidr = *decision.Value
}
_, cidrNet, err := net.ParseCIDR(cidr)
if err != nil {
return err
}
if err := n.conn.Flush(); err != nil {
if err := n.conn6.SetDeleteElements(n.set6,
[]nftables.SetElement{
{Key: []byte(cidrNet.IP.To16())},
{Key: []byte(incrementIP(BroadcastAddr(cidrNet)).To16()), IntervalEnd: true},
}); err != nil {
return err
}
if err := n.conn6.Flush(); err != nil {
return err
}

} else {
log.Debugf("not adding '%s' because ipv6 is disabled", *decision.Value)
log.Debugf("not removing '%s' because ipv6 is disabled", *decision.Value)
return nil
}
} else { // ipv4
var ipAddr string
if strings.Contains(*decision.Value, "/") {
ipAddr = strings.Split(*decision.Value, "/")[0]
var cidr string
if !strings.Contains(*decision.Value, "/") {
cidr = fmt.Sprintf("%s/32", *decision.Value)
} else {
ipAddr = *decision.Value
cidr = *decision.Value
}
_, cidrNet, err := net.ParseCIDR(cidr)
if err != nil {
return err
}
if err := n.conn.SetDeleteElements(n.set, []nftables.SetElement{{Key: net.ParseIP(ipAddr).To4()}}); err != nil {
if err := n.conn.SetDeleteElements(n.set,
[]nftables.SetElement{
{Key: cidrNet.IP},
{Key: incrementIP(BroadcastAddr(cidrNet)), IntervalEnd: true},
}); err != nil {
return err
}
if err := n.conn.Flush(); err != nil {
Expand All @@ -269,3 +318,44 @@ func (n *nft) ShutDown() error {
}
return nil
}

// Utilites from https://github.com/IBM/netaddr/blob/master/net_utils.go

// NewIP returns a new IP with the given size. The size must be 4 for IPv4 and
// 16 for IPv6.
func NewIP(size int) net.IP {
if size == 4 {
return net.ParseIP("0.0.0.0").To4()
}
if size == 16 {
return net.ParseIP("::")
}
panic("Bad value for size")
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}

// BroadcastAddr returns the last address in the given network, or the broadcast address.
func BroadcastAddr(n *net.IPNet) net.IP {
// The golang net package doesn't make it easy to calculate the broadcast address. :(
broadcast := NewIP(len(n.IP))
for i := 0; i < len(n.IP); i++ {
broadcast[i] = n.IP[i] | ^n.Mask[i]
}
return broadcast
}

// incrementIP returns the given IP + 1
func incrementIP(ip net.IP) (result net.IP) {
result = make([]byte, len(ip)) // start off with a nice empty ip of proper length

carry := true
for i := len(ip) - 1; i >= 0; i-- {
result[i] = ip[i]
if carry {
result[i]++
if result[i] != 0 {
carry = false
}
}
}
return
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}