AdGuardHome/internal/dnsforward/ipset_linux.go

401 lines
9.6 KiB
Go

// +build linux
package dnsforward
import (
"fmt"
"net"
"strings"
"sync"
"github.com/AdguardTeam/AdGuardHome/internal/agherr"
"github.com/AdguardTeam/golibs/log"
"github.com/digineo/go-ipset/v2"
"github.com/mdlayher/netlink"
"github.com/miekg/dns"
"github.com/ti-mo/netfilter"
)
// TODO(a.garipov): Cover with unit tests as well as document how to test it
// manually. The original PR by @dsheets on Github contained an integration
// test, but unfortunately I didn't have the time to properly refactor it and
// check it in.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/2611.
// ipsetProps contains one Linux Netfilter ipset properties.
type ipsetProps struct {
name string
family netfilter.ProtoFamily
}
// ipsetCtx is the Linux Netfilter ipset context.
type ipsetCtx struct {
// mu protects all properties below.
mu *sync.Mutex
nameToIpset map[string]ipsetProps
domainToIpsets map[string][]ipsetProps
// TODO(a.garipov): Currently, the ipset list is static, and we don't
// read the IPs already in sets, so we can assume that all incoming IPs
// are either added to all corresponding ipsets or not. When that stops
// being the case, for example if we add dynamic reconfiguration of
// ipsets, this map will need to become a per-ipset-name one.
addedIPs map[[16]byte]struct{}
ipv4Conn *ipset.Conn
ipv6Conn *ipset.Conn
}
// dialNetfilter establishes connections to Linux's netfilter module.
func (c *ipsetCtx) dialNetfilter(config *netlink.Config) (err error) {
// The kernel API does not actually require two sockets but package
// github.com/digineo/go-ipset does.
//
// TODO(a.garipov): Perhaps we can ditch package ipset altogether and
// just use packages netfilter and netlink.
c.ipv4Conn, err = ipset.Dial(netfilter.ProtoIPv4, config)
if err != nil {
return fmt.Errorf("dialing v4: %w", err)
}
c.ipv6Conn, err = ipset.Dial(netfilter.ProtoIPv6, config)
if err != nil {
return fmt.Errorf("dialing v6: %w", err)
}
return nil
}
// ipsetProps returns the properties of an ipset with the given name.
func (c *ipsetCtx) ipsetProps(name string) (set ipsetProps, err error) {
// The family doesn't seem to matter when we use a header query, so
// query only the IPv4 one.
//
// TODO(a.garipov): Find out if this is a bug or a feature.
var res *ipset.HeaderPolicy
res, err = c.ipv4Conn.Header(name)
if err != nil {
return set, err
}
if res == nil || res.Family == nil {
return set, agherr.Error("empty response or no family data")
}
family := netfilter.ProtoFamily(res.Family.Value)
if family != netfilter.ProtoIPv4 && family != netfilter.ProtoIPv6 {
return set, fmt.Errorf("unexpected ipset family %s", family)
}
return ipsetProps{
name: name,
family: family,
}, nil
}
// ipsets returns currently known ipsets.
func (c *ipsetCtx) ipsets(names []string) (sets []ipsetProps, err error) {
for _, name := range names {
set, ok := c.nameToIpset[name]
if ok {
sets = append(sets, set)
continue
}
set, err = c.ipsetProps(name)
if err != nil {
return nil, fmt.Errorf("querying ipset %q: %w", name, err)
}
c.nameToIpset[name] = set
sets = append(sets, set)
}
return sets, nil
}
// parseIpsetConfig parses one ipset configuration string.
func parseIpsetConfig(cfgStr string) (hosts, ipsetNames []string, err error) {
cfgStr = strings.TrimSpace(cfgStr)
hostsAndNames := strings.Split(cfgStr, "/")
if len(hostsAndNames) != 2 {
return nil, nil, fmt.Errorf("invalid value %q: expected one slash", cfgStr)
}
hosts = strings.Split(hostsAndNames[0], ",")
ipsetNames = strings.Split(hostsAndNames[1], ",")
if len(ipsetNames) == 0 {
log.Info("ipset: resolutions for %q will not be stored", hosts)
return nil, nil, nil
}
for i := range ipsetNames {
ipsetNames[i] = strings.TrimSpace(ipsetNames[i])
if len(ipsetNames[i]) == 0 {
return nil, nil, fmt.Errorf("invalid value %q: empty ipset name", cfgStr)
}
}
for i := range hosts {
hosts[i] = strings.TrimSpace(hosts[i])
hosts[i] = strings.ToLower(hosts[i])
if len(hosts[i]) == 0 {
log.Info("ipset: root catchall in %q", ipsetNames)
}
}
return hosts, ipsetNames, nil
}
// init initializes the ipset context. It is not safe for concurrent use.
//
// TODO(a.garipov): Rewrite into a simple constructor?
func (c *ipsetCtx) init(ipsetConfig []string) (err error) {
c.mu = &sync.Mutex{}
c.nameToIpset = make(map[string]ipsetProps)
c.domainToIpsets = make(map[string][]ipsetProps)
c.addedIPs = make(map[[16]byte]struct{})
err = c.dialNetfilter(&netlink.Config{})
if err != nil {
return fmt.Errorf("ipset: dialing netfilter: %w", err)
}
for i, cfgStr := range ipsetConfig {
var hosts, ipsetNames []string
hosts, ipsetNames, err = parseIpsetConfig(cfgStr)
if err != nil {
return fmt.Errorf("ipset: config line at index %d: %w", i, err)
}
var ipsets []ipsetProps
ipsets, err = c.ipsets(ipsetNames)
if err != nil {
return fmt.Errorf("ipset: getting ipsets config line at index %d: %w", i, err)
}
for _, host := range hosts {
c.domainToIpsets[host] = append(c.domainToIpsets[host], ipsets...)
}
}
log.Debug("ipset: added %d domains for %d ipsets", len(c.domainToIpsets), len(c.nameToIpset))
return nil
}
// Close closes the Linux Netfilter connections.
func (c *ipsetCtx) Close() (err error) {
var errors []error
if c.ipv4Conn != nil {
err = c.ipv4Conn.Close()
if err != nil {
errors = append(errors, err)
}
}
if c.ipv6Conn != nil {
err = c.ipv6Conn.Close()
if err != nil {
errors = append(errors, err)
}
}
if len(errors) != 0 {
return agherr.Many("closing ipsets", errors...)
}
return nil
}
// ipFromRR returns an IP address from a DNS resource record.
func ipFromRR(rr dns.RR) (ip net.IP) {
switch a := rr.(type) {
case *dns.A:
return a.A
case *dns.AAAA:
return a.AAAA
default:
return nil
}
}
// lookupHost find the ipsets for the host, taking subdomain wildcards into
// account.
func (c *ipsetCtx) lookupHost(host string) (sets []ipsetProps) {
// Search for matching ipset hosts starting with most specific
// subdomain. We could use a trie here but the simple, inefficient
// solution isn't that expensive. ~75 % for 10 subdomains vs 0, but
// still sub-microsecond on a Core i7.
//
// TODO(a.garipov): Re-add benchmarks from the original PR.
for i := 0; i != -1; i++ {
host = host[i:]
sets = c.domainToIpsets[host]
if sets != nil {
return sets
}
i = strings.Index(host, ".")
if i == -1 {
break
}
}
// Check the root catch-all one.
return c.domainToIpsets[""]
}
// addIPs adds the IP addresses for the host to the ipset. set must be same
// family as set's family.
func (c *ipsetCtx) addIPs(host string, set ipsetProps, ips []net.IP) (err error) {
if len(ips) == 0 {
return
}
entries := make([]*ipset.Entry, 0, len(ips))
for _, ip := range ips {
entries = append(entries, ipset.NewEntry(ipset.EntryIP(ip)))
}
var conn *ipset.Conn
switch set.family {
case netfilter.ProtoIPv4:
conn = c.ipv4Conn
case netfilter.ProtoIPv6:
conn = c.ipv6Conn
default:
return fmt.Errorf("unexpected family %s for ipset %q", set.family, set.name)
}
err = conn.Add(set.name, entries...)
if err != nil {
return fmt.Errorf("adding %q%s to ipset %q: %w", host, ips, set.name, err)
}
log.Debug("ipset: added %s%s to ipset %s", host, ips, set.name)
return nil
}
// skipIpsetProcessing returns true when the ipset processing can be skipped for
// this request.
func (c *ipsetCtx) skipIpsetProcessing(ctx *dnsContext) (ok bool) {
if len(c.domainToIpsets) == 0 || ctx == nil || !ctx.responseFromUpstream {
return true
}
req := ctx.proxyCtx.Req
if req == nil || len(req.Question) == 0 {
return true
}
qt := req.Question[0].Qtype
return qt != dns.TypeA && qt != dns.TypeAAAA && qt != dns.TypeANY
}
// process adds the resolved IP addresses to the domain's ipsets, if any.
func (c *ipsetCtx) process(ctx *dnsContext) (rc resultCode) {
var err error
if c == nil {
return resultCodeSuccess
}
log.Debug("ipset: starting processing")
c.mu.Lock()
defer c.mu.Unlock()
if c.skipIpsetProcessing(ctx) {
log.Debug("ipset: skipped processing for request")
return resultCodeSuccess
}
req := ctx.proxyCtx.Req
host := req.Question[0].Name
host = strings.TrimSuffix(host, ".")
host = strings.ToLower(host)
sets := c.lookupHost(host)
if len(sets) == 0 {
log.Debug("ipset: no ipsets for host %s", host)
return resultCodeSuccess
}
log.Debug("ipset: found ipsets %+v for host %s", sets, host)
if ctx.proxyCtx.Res == nil {
return resultCodeSuccess
}
ans := ctx.proxyCtx.Res.Answer
l := len(ans)
v4s := make([]net.IP, 0, l)
v6s := make([]net.IP, 0, l)
for _, rr := range ans {
ip := ipFromRR(rr)
if ip == nil {
continue
}
var iparr [16]byte
copy(iparr[:], ip.To16())
if _, added := c.addedIPs[iparr]; added {
continue
}
if ip.To4() == nil {
v6s = append(v6s, ip)
continue
}
v4s = append(v4s, ip)
}
setLoop:
for _, set := range sets {
switch set.family {
case netfilter.ProtoIPv4:
err = c.addIPs(host, set, v4s)
if err != nil {
break setLoop
}
case netfilter.ProtoIPv6:
err = c.addIPs(host, set, v6s)
if err != nil {
break setLoop
}
default:
err = fmt.Errorf("unexpected family %s for ipset %q", set.family, set.name)
break setLoop
}
}
if err != nil {
log.Error("ipset: adding host ips: %s", err)
} else {
log.Debug("ipset: processed %d new ips", len(v4s)+len(v6s))
}
for _, ip := range v4s {
var iparr [16]byte
copy(iparr[:], ip.To16())
c.addedIPs[iparr] = struct{}{}
}
for _, ip := range v6s {
var iparr [16]byte
copy(iparr[:], ip.To16())
c.addedIPs[iparr] = struct{}{}
}
return resultCodeSuccess
}