From a0438d14182a933d621bd51ac1c747cdee5b6758 Mon Sep 17 00:00:00 2001 From: Vadym Vikulin Date: Thu, 8 Jul 2021 13:47:34 -0700 Subject: [PATCH] 1. added ckr back --- src/tuntap/ckr.go | 430 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 430 insertions(+) create mode 100644 src/tuntap/ckr.go diff --git a/src/tuntap/ckr.go b/src/tuntap/ckr.go new file mode 100644 index 00000000..fdb2bbdc --- /dev/null +++ b/src/tuntap/ckr.go @@ -0,0 +1,430 @@ +package tuntap + +import ( + "bytes" + "encoding/hex" + "errors" + "fmt" + "net" + "sort" + "sync" + "sync/atomic" + + "github.com/yggdrasil-network/yggdrasil-go/src/address" + "github.com/yggdrasil-network/yggdrasil-go/src/crypto" +) + +// This module implements crypto-key routing, similar to Wireguard, where we +// allow traffic for non-Yggdrasil ranges to be routed over Yggdrasil. + +type cryptokey struct { + tun *TunAdapter + enabled atomic.Value // bool + ipv4remotes []cryptokey_route + ipv6remotes []cryptokey_route + ipv4cache map[address.Address]cryptokey_route + ipv6cache map[address.Address]cryptokey_route + ipv4locals []net.IPNet + ipv6locals []net.IPNet + mutexremotes sync.RWMutex + mutexcaches sync.RWMutex + mutexlocals sync.RWMutex +} + +type cryptokey_route struct { + subnet net.IPNet + destination crypto.BoxPubKey +} + +// Initialise crypto-key routing. This must be done before any other CKR calls. +func (c *cryptokey) init(tun *TunAdapter) { + c.tun = tun + c.configure() +} + +// Configure the CKR routes. This should only ever be ran by the TUN/TAP actor. +func (c *cryptokey) configure() { + current := c.tun.config.GetCurrent() + + // Set enabled/disabled state + c.setEnabled(current.TunnelRouting.Enable) + + // Clear out existing routes + c.mutexremotes.Lock() + c.ipv6remotes = make([]cryptokey_route, 0) + c.ipv4remotes = make([]cryptokey_route, 0) + c.mutexremotes.Unlock() + + // Add IPv6 routes + for ipv6, pubkey := range current.TunnelRouting.IPv6RemoteSubnets { + if err := c.addRemoteSubnet(ipv6, pubkey); err != nil { + c.tun.log.Errorln("Error adding CKR IPv6 remote subnet:", err) + } + } + + // Add IPv4 routes + for ipv4, pubkey := range current.TunnelRouting.IPv4RemoteSubnets { + if err := c.addRemoteSubnet(ipv4, pubkey); err != nil { + c.tun.log.Errorln("Error adding CKR IPv4 remote subnet:", err) + } + } + + // Clear out existing sources + c.mutexlocals.Lock() + c.ipv6locals = make([]net.IPNet, 0) + c.ipv4locals = make([]net.IPNet, 0) + c.mutexlocals.Unlock() + + // Add IPv6 sources + c.ipv6locals = make([]net.IPNet, 0) + for _, source := range current.TunnelRouting.IPv6LocalSubnets { + if err := c.addLocalSubnet(source); err != nil { + c.tun.log.Errorln("Error adding CKR IPv6 local subnet:", err) + } + } + + // Add IPv4 sources + c.ipv4locals = make([]net.IPNet, 0) + for _, source := range current.TunnelRouting.IPv4LocalSubnets { + if err := c.addLocalSubnet(source); err != nil { + c.tun.log.Errorln("Error adding CKR IPv4 local subnet:", err) + } + } + + // Wipe the caches + c.mutexcaches.Lock() + c.ipv4cache = make(map[address.Address]cryptokey_route, 0) + c.ipv6cache = make(map[address.Address]cryptokey_route, 0) + c.mutexcaches.Unlock() +} + +// Enable or disable crypto-key routing. +func (c *cryptokey) setEnabled(enabled bool) { + c.enabled.Store(enabled) +} + +// Check if crypto-key routing is enabled. +func (c *cryptokey) isEnabled() bool { + enabled, ok := c.enabled.Load().(bool) + return ok && enabled +} + +// Check whether the given address (with the address length specified in bytes) +// matches either the current node's address, the node's routed subnet or the +// list of subnets specified in ipv4locals/ipv6locals. +func (c *cryptokey) isValidLocalAddress(addr address.Address, addrlen int) bool { + c.mutexlocals.RLock() + defer c.mutexlocals.RUnlock() + // Does it match a configured CKR source? + if c.isEnabled() { + ip := net.IP(addr[:addrlen]) + // Build our references to the routing sources + var routingsources *[]net.IPNet + + // Check if the prefix is IPv4 or IPv6 + if addrlen == net.IPv6len { + routingsources = &c.ipv6locals + } else if addrlen == net.IPv4len { + routingsources = &c.ipv4locals + } else { + return false + } + + for _, subnet := range *routingsources { + if subnet.Contains(ip) { + return true + } + } + } + + // Doesn't match any of the above + return false +} + +// Adds a source subnet, which allows traffic with these source addresses to +// be tunnelled using crypto-key routing. +func (c *cryptokey) addLocalSubnet(cidr string) error { + c.mutexlocals.Lock() + defer c.mutexlocals.Unlock() + + // Is the CIDR we've been given valid? + _, ipnet, err := net.ParseCIDR(cidr) + if err != nil { + return err + } + + // Get the prefix length and size + _, prefixsize := ipnet.Mask.Size() + + // Build our references to the routing sources + var routingsources *[]net.IPNet + + // Check if the prefix is IPv4 or IPv6 + if prefixsize == net.IPv6len*8 { + routingsources = &c.ipv6locals + } else if prefixsize == net.IPv4len*8 { + routingsources = &c.ipv4locals + } else { + return errors.New("unexpected prefix size") + } + + // Check if we already have this CIDR + for _, subnet := range *routingsources { + if subnet.String() == ipnet.String() { + return errors.New("local subnet already configured") + } + } + + // Add the source subnet + *routingsources = append(*routingsources, *ipnet) + c.tun.log.Infoln("Added CKR local subnet", cidr) + return nil +} + +// Adds a destination route for the given CIDR to be tunnelled to the node +// with the given BoxPubKey. +func (c *cryptokey) addRemoteSubnet(cidr string, dest string) error { + c.mutexremotes.Lock() + c.mutexcaches.Lock() + defer c.mutexremotes.Unlock() + defer c.mutexcaches.Unlock() + + // Is the CIDR we've been given valid? + ipaddr, ipnet, err := net.ParseCIDR(cidr) + if err != nil { + return err + } + + // Get the prefix length and size + _, prefixsize := ipnet.Mask.Size() + + // Build our references to the routing table and cache + var routingtable *[]cryptokey_route + var routingcache *map[address.Address]cryptokey_route + + // Check if the prefix is IPv4 or IPv6 + if prefixsize == net.IPv6len*8 { + routingtable = &c.ipv6remotes + routingcache = &c.ipv6cache + } else if prefixsize == net.IPv4len*8 { + routingtable = &c.ipv4remotes + routingcache = &c.ipv4cache + } else { + return errors.New("unexpected prefix size") + } + + // Is the route an Yggdrasil destination? + var addr address.Address + var snet address.Subnet + copy(addr[:], ipaddr) + copy(snet[:], ipnet.IP) + if addr.IsValid() || snet.IsValid() { + return errors.New("can't specify Yggdrasil destination as crypto-key route") + } + // Do we already have a route for this subnet? + for _, route := range *routingtable { + if route.subnet.String() == ipnet.String() { + return fmt.Errorf("remote subnet already exists for %s", cidr) + } + } + // Decode the public key + if bpk, err := hex.DecodeString(dest); err != nil { + return err + } else if len(bpk) != crypto.BoxPubKeyLen { + return fmt.Errorf("incorrect key length for %s", dest) + } else { + // Add the new crypto-key route + var key crypto.BoxPubKey + copy(key[:], bpk) + *routingtable = append(*routingtable, cryptokey_route{ + subnet: *ipnet, + destination: key, + }) + + // Sort so most specific routes are first + sort.Slice(*routingtable, func(i, j int) bool { + im, _ := (*routingtable)[i].subnet.Mask.Size() + jm, _ := (*routingtable)[j].subnet.Mask.Size() + return im > jm + }) + + // Clear the cache as this route might change future routing + // Setting an empty slice keeps the memory whereas nil invokes GC + for k := range *routingcache { + delete(*routingcache, k) + } + + c.tun.log.Infoln("Added CKR remote subnet", cidr) + return nil + } +} + +// Looks up the most specific route for the given address (with the address +// length specified in bytes) from the crypto-key routing table. An error is +// returned if the address is not suitable or no route was found. +func (c *cryptokey) getPublicKeyForAddress(addr address.Address, addrlen int) (crypto.BoxPubKey, error) { + + // Check if the address is a valid Yggdrasil address - if so it + // is exempt from all CKR checking + if addr.IsValid() { + return crypto.BoxPubKey{}, errors.New("cannot look up CKR for Yggdrasil addresses") + } + + // Build our references to the routing table and cache + var routingtable *[]cryptokey_route + var routingcache *map[address.Address]cryptokey_route + + // Check if the prefix is IPv4 or IPv6 + if addrlen == net.IPv6len { + routingcache = &c.ipv6cache + } else if addrlen == net.IPv4len { + routingcache = &c.ipv4cache + } else { + return crypto.BoxPubKey{}, errors.New("unexpected prefix size") + } + + // Check if there's a cache entry for this addr + c.mutexcaches.RLock() + if route, ok := (*routingcache)[addr]; ok { + c.mutexcaches.RUnlock() + return route.destination, nil + } + c.mutexcaches.RUnlock() + + c.mutexremotes.RLock() + defer c.mutexremotes.RUnlock() + + // Check if the prefix is IPv4 or IPv6 + if addrlen == net.IPv6len { + routingtable = &c.ipv6remotes + } else if addrlen == net.IPv4len { + routingtable = &c.ipv4remotes + } else { + return crypto.BoxPubKey{}, errors.New("unexpected prefix size") + } + + // No cache was found - start by converting the address into a net.IP + ip := make(net.IP, addrlen) + copy(ip[:addrlen], addr[:]) + + // Check if we have a route. At this point c.ipv6remotes should be + // pre-sorted so that the most specific routes are first + for _, route := range *routingtable { + // Does this subnet match the given IP? + if route.subnet.Contains(ip) { + c.mutexcaches.Lock() + defer c.mutexcaches.Unlock() + + // Check if the routing cache is above a certain size, if it is evict + // a random entry so we can make room for this one. We take advantage + // of the fact that the iteration order is random here + for k := range *routingcache { + if len(*routingcache) < 1024 { + break + } + delete(*routingcache, k) + } + + // Cache the entry for future packets to get a faster lookup + (*routingcache)[addr] = route + + // Return the boxPubKey + return route.destination, nil + } + } + + // No route was found if we got to this point + return crypto.BoxPubKey{}, fmt.Errorf("no route to %s", ip.String()) +} + +// Removes a source subnet, which allows traffic with these source addresses to +// be tunnelled using crypto-key routing. +func (c *cryptokey) removeLocalSubnet(cidr string) error { + c.mutexlocals.Lock() + defer c.mutexlocals.Unlock() + + // Is the CIDR we've been given valid? + _, ipnet, err := net.ParseCIDR(cidr) + if err != nil { + return err + } + + // Get the prefix length and size + _, prefixsize := ipnet.Mask.Size() + + // Build our references to the routing sources + var routingsources *[]net.IPNet + + // Check if the prefix is IPv4 or IPv6 + if prefixsize == net.IPv6len*8 { + routingsources = &c.ipv6locals + } else if prefixsize == net.IPv4len*8 { + routingsources = &c.ipv4locals + } else { + return errors.New("unexpected prefix size") + } + + // Check if we already have this CIDR + for idx, subnet := range *routingsources { + if subnet.String() == ipnet.String() { + *routingsources = append((*routingsources)[:idx], (*routingsources)[idx+1:]...) + c.tun.log.Infoln("Removed CKR local subnet", cidr) + return nil + } + } + return errors.New("local subnet not found") +} + +// Removes a destination route for the given CIDR to be tunnelled to the node +// with the given BoxPubKey. +func (c *cryptokey) removeRemoteSubnet(cidr string, dest string) error { + c.mutexremotes.Lock() + c.mutexcaches.Lock() + defer c.mutexremotes.Unlock() + defer c.mutexcaches.Unlock() + + // Is the CIDR we've been given valid? + _, ipnet, err := net.ParseCIDR(cidr) + if err != nil { + return err + } + + // Get the prefix length and size + _, prefixsize := ipnet.Mask.Size() + + // Build our references to the routing table and cache + var routingtable *[]cryptokey_route + var routingcache *map[address.Address]cryptokey_route + + // Check if the prefix is IPv4 or IPv6 + if prefixsize == net.IPv6len*8 { + routingtable = &c.ipv6remotes + routingcache = &c.ipv6cache + } else if prefixsize == net.IPv4len*8 { + routingtable = &c.ipv4remotes + routingcache = &c.ipv4cache + } else { + return errors.New("unexpected prefix size") + } + + // Decode the public key + bpk, err := hex.DecodeString(dest) + if err != nil { + return err + } else if len(bpk) != crypto.BoxPubKeyLen { + return fmt.Errorf("incorrect key length for %s", dest) + } + netStr := ipnet.String() + + for idx, route := range *routingtable { + if bytes.Equal(route.destination[:], bpk) && route.subnet.String() == netStr { + *routingtable = append((*routingtable)[:idx], (*routingtable)[idx+1:]...) + for k := range *routingcache { + delete(*routingcache, k) + } + c.tun.log.Infof("Removed CKR remote subnet %s via %s\n", cidr, dest) + return nil + } + } + return fmt.Errorf("route does not exists for %s", cidr) +}