policy manager

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/app.go

@@ -30,6 +30,7 @@ import (
 	"github.com/juanfont/headscale/hscontrol/mapper"
 	"github.com/juanfont/headscale/hscontrol/notifier"
 	"github.com/juanfont/headscale/hscontrol/policy"
+	"github.com/juanfont/headscale/hscontrol/policyv2"
 	"github.com/juanfont/headscale/hscontrol/types"
 	"github.com/juanfont/headscale/hscontrol/util"
 	zerolog "github.com/philip-bui/grpc-zerolog"
@@ -89,6 +90,7 @@ type Headscale struct {
 	DERPServer *derpServer.DERPServer
 
 	ACLPolicy     *policy.ACLPolicy
+	PolicyManager *policyv2.PolicyManager
 
 	mapper       *mapper.Mapper
 	nodeNotifier *notifier.Notifier

hscontrol/policyv2/filter.go

@@ -3,6 +3,7 @@ package policyv2
 import (
 	"errors"
 	"fmt"
+	"time"
 
 	"github.com/juanfont/headscale/hscontrol/types"
 	"go4.org/netipx"
@@ -16,6 +17,7 @@ var (
 // CompileFilterRules takes a set of nodes and an ACLPolicy and generates a
 // set of Tailscale compatible FilterRules used to allow traffic on clients.
 func (pol *Policy) CompileFilterRules(
+	users types.Users,
 	nodes types.Nodes,
 ) ([]tailcfg.FilterRule, error) {
 	if pol == nil {
@@ -29,7 +31,7 @@ func (pol *Policy) CompileFilterRules(
 			return nil, ErrInvalidAction
 		}
 
-		srcIPs, err := acl.Sources.Resolve(pol, nodes)
+		srcIPs, err := acl.Sources.Resolve(pol, users, nodes)
 		if err != nil {
 			return nil, fmt.Errorf("resolving source ips: %w", err)
 		}
@@ -43,7 +45,7 @@ func (pol *Policy) CompileFilterRules(
 
 		var destPorts []tailcfg.NetPortRange
 		for _, dest := range acl.Destinations {
-			ips, err := dest.Alias.Resolve(pol, nodes)
+			ips, err := dest.Alias.Resolve(pol, users, nodes)
 			if err != nil {
 				return nil, err
 			}
@@ -69,6 +71,105 @@ func (pol *Policy) CompileFilterRules(
 	return rules, nil
 }
 
+func sshAction(accept bool, duration time.Duration) tailcfg.SSHAction {
+	return tailcfg.SSHAction{
+		Reject:                   !accept,
+		Accept:                   accept,
+		SessionDuration:          duration,
+		AllowAgentForwarding:     true,
+		AllowLocalPortForwarding: true,
+	}
+}
+
+func (pol *Policy) CompileSSHPolicy(
+	users types.Users,
+	node types.Node,
+	nodes types.Nodes,
+) (*tailcfg.SSHPolicy, error) {
+	if pol == nil {
+		return nil, nil
+	}
+
+	var rules []*tailcfg.SSHRule
+
+	for index, rule := range pol.SSHs {
+		var dest netipx.IPSetBuilder
+		for _, src := range rule.Destinations {
+			ips, err := src.Resolve(pol, users, nodes)
+			if err != nil {
+				return nil, err
+			}
+			dest.AddSet(ips)
+		}
+
+		destSet, err := dest.IPSet()
+		if err != nil {
+			return nil, err
+		}
+
+		if !node.InIPSet(destSet) {
+			continue
+		}
+
+		var action tailcfg.SSHAction
+		switch rule.Action {
+		case "accept":
+			action = sshAction(true, 0)
+		case "check":
+			action = sshAction(true, rule.CheckPeriod)
+		default:
+			return nil, fmt.Errorf("parsing SSH policy, unknown action %q, index: %d: %w", rule.Action, index, err)
+		}
+
+		var principals []*tailcfg.SSHPrincipal
+		for _, src := range rule.Sources {
+			if isWildcard(rawSrc) {
+				principals = append(principals, &tailcfg.SSHPrincipal{
+					Any: true,
+				})
+			} else if isGroup(rawSrc) {
+				users, err := pol.expandUsersFromGroup(rawSrc)
+				if err != nil {
+					return nil, fmt.Errorf("parsing SSH policy, expanding user from group, index: %d->%d: %w", index, innerIndex, err)
+				}
+
+				for _, user := range users {
+					principals = append(principals, &tailcfg.SSHPrincipal{
+						UserLogin: user,
+					})
+				}
+			} else {
+				expandedSrcs, err := pol.ExpandAlias(
+					peers,
+					rawSrc,
+				)
+				if err != nil {
+					return nil, fmt.Errorf("parsing SSH policy, expanding alias, index: %d->%d: %w", index, innerIndex, err)
+				}
+				for _, expandedSrc := range expandedSrcs.Prefixes() {
+					principals = append(principals, &tailcfg.SSHPrincipal{
+						NodeIP: expandedSrc.Addr().String(),
+					})
+				}
+			}
+		}
+
+		userMap := make(map[string]string, len(rule.Users))
+		for _, user := range rule.Users {
+			userMap[user] = "="
+		}
+		rules = append(rules, &tailcfg.SSHRule{
+			Principals: principals,
+			SSHUsers:   userMap,
+			Action:     &action,
+		})
+	}
+
+	return &tailcfg.SSHPolicy{
+		Rules: rules,
+	}, nil
+}
+
 func ipSetToPrefixStringList(ips *netipx.IPSet) []string {
 	var out []string
 

hscontrol/policyv2/filter_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/juanfont/headscale/hscontrol/policy"
 	"github.com/juanfont/headscale/hscontrol/types"
 	"github.com/rs/zerolog/log"
+	"gorm.io/gorm"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tailcfg"
 )
@@ -17,6 +18,9 @@ import (
 // Move it here, run it against both old and new CompileFilterRules
 
 func TestParsing(t *testing.T) {
+	users := types.Users{
+		{Model: gorm.Model{ID: 1}, Name: "testuser@"},
+	}
 	tests := []struct {
 		name    string
 		format  string
@@ -340,7 +344,7 @@ func TestParsing(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			pol, err := PolicyFromBytes([]byte(tt.acl))
+			pol, err := policyFromBytes([]byte(tt.acl))
 			if tt.wantErr && err == nil {
 				t.Errorf("parsing() error = %v, wantErr %v", err, tt.wantErr)
 
@@ -355,15 +359,15 @@ func TestParsing(t *testing.T) {
 				return
 			}
 
-			rules, err := pol.CompileFilterRules(types.Nodes{
+			rules, err := pol.CompileFilterRules(
+				users,
+				types.Nodes{
 					&types.Node{
 						IPv4: ap("100.100.100.100"),
 					},
 					&types.Node{
 						IPv4:     ap("200.200.200.200"),
-					User: types.User{
+						User:     users[0],
-						Name: "testuser@",
-					},
 						Hostinfo: &tailcfg.Hostinfo{},
 					},
 				})
@@ -435,6 +439,14 @@ var hsExitNodeDestForTest = []tailcfg.NetPortRange{
 }
 
 func TestReduceFilterRules(t *testing.T) {
+	users := types.Users{
+		types.User{Model: gorm.Model{ID: 1}, Name: "mickael"},
+		types.User{Model: gorm.Model{ID: 2}, Name: "user1@"},
+		types.User{Model: gorm.Model{ID: 3}, Name: "user2@"},
+		types.User{Model: gorm.Model{ID: 4}, Name: "user100@"},
+		types.User{Model: gorm.Model{ID: 5}, Name: "user3@"},
+	}
+
 	tests := []struct {
 		name  string
 		node  *types.Node
@@ -463,13 +475,13 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.1"),
 				IPv6: ap("fd7a:115c:a1e0:ab12:4843:2222:6273:2221"),
-				User: types.User{Name: "mickael"},
+				User: users[0],
 			},
 			peers: types.Nodes{
 				&types.Node{
 					IPv4: ap("100.64.0.2"),
 					IPv6: ap("fd7a:115c:a1e0:ab12:4843:2222:6273:2222"),
-					User: types.User{Name: "mickael"},
+					User: users[0],
 				},
 			},
 			want: []tailcfg.FilterRule{},
@@ -510,7 +522,7 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.1"),
 				IPv6: ap("fd7a:115c:a1e0::1"),
-				User: types.User{Name: "user1@"},
+				User: users[1],
 				Hostinfo: &tailcfg.Hostinfo{
 					RoutableIPs: []netip.Prefix{
 						netip.MustParsePrefix("10.33.0.0/16"),
@@ -521,7 +533,7 @@ func TestReduceFilterRules(t *testing.T) {
 				&types.Node{
 					IPv4: ap("100.64.0.2"),
 					IPv6: ap("fd7a:115c:a1e0::2"),
-					User: types.User{Name: "user1@"},
+					User: users[1],
 				},
 			},
 			want: []tailcfg.FilterRule{
@@ -600,19 +612,19 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.1"),
 				IPv6: ap("fd7a:115c:a1e0::1"),
-				User: types.User{Name: "user1@"},
+				User: users[1],
 			},
 			peers: types.Nodes{
 				&types.Node{
 					IPv4: ap("100.64.0.2"),
 					IPv6: ap("fd7a:115c:a1e0::2"),
-					User: types.User{Name: "user2@"},
+					User: users[2],
 				},
 				// "internal" exit node
 				&types.Node{
 					IPv4: ap("100.64.0.100"),
 					IPv6: ap("fd7a:115c:a1e0::100"),
-					User: types.User{Name: "user100@"},
+					User: users[3],
 					Hostinfo: &tailcfg.Hostinfo{
 						RoutableIPs: tsaddr.ExitRoutes(),
 					},
@@ -661,7 +673,7 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.100"),
 				IPv6: ap("fd7a:115c:a1e0::100"),
-				User: types.User{Name: "user100@"},
+				User: users[3],
 				Hostinfo: &tailcfg.Hostinfo{
 					RoutableIPs: tsaddr.ExitRoutes(),
 				},
@@ -670,12 +682,12 @@ func TestReduceFilterRules(t *testing.T) {
 				&types.Node{
 					IPv4: ap("100.64.0.2"),
 					IPv6: ap("fd7a:115c:a1e0::2"),
-					User: types.User{Name: "user2@"},
+					User: users[2],
 				},
 				&types.Node{
 					IPv4: ap("100.64.0.1"),
 					IPv6: ap("fd7a:115c:a1e0::1"),
-					User: types.User{Name: "user1@"},
+					User: users[1],
 				},
 			},
 			want: []tailcfg.FilterRule{
@@ -768,7 +780,7 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.100"),
 				IPv6: ap("fd7a:115c:a1e0::100"),
-				User: types.User{Name: "user100@"},
+				User: users[3],
 				Hostinfo: &tailcfg.Hostinfo{
 					RoutableIPs: tsaddr.ExitRoutes(),
 				},
@@ -777,12 +789,12 @@ func TestReduceFilterRules(t *testing.T) {
 				&types.Node{
 					IPv4: ap("100.64.0.2"),
 					IPv6: ap("fd7a:115c:a1e0::2"),
-					User: types.User{Name: "user2@"},
+					User: users[2],
 				},
 				&types.Node{
 					IPv4: ap("100.64.0.1"),
 					IPv6: ap("fd7a:115c:a1e0::1"),
-					User: types.User{Name: "user1@"},
+					User: users[1],
 				},
 			},
 			want: []tailcfg.FilterRule{
@@ -809,9 +821,11 @@ func TestReduceFilterRules(t *testing.T) {
 						{IP: "16.0.0.0/4", Ports: tailcfg.PortRangeAny},
 						{IP: "32.0.0.0/3", Ports: tailcfg.PortRangeAny},
 						{IP: "64.0.0.0/2", Ports: tailcfg.PortRangeAny},
-						{IP: "fd7a:115c:a1e0::1/128", Ports: tailcfg.PortRangeAny},
+						// This should not be included I believe, seems like
-						{IP: "fd7a:115c:a1e0::2/128", Ports: tailcfg.PortRangeAny},
+						// this is a bug in the v1 code.
-						{IP: "fd7a:115c:a1e0::100/128", Ports: tailcfg.PortRangeAny},
+						// {IP: "fd7a:115c:a1e0::1/128", Ports: tailcfg.PortRangeAny},
+						// {IP: "fd7a:115c:a1e0::2/128", Ports: tailcfg.PortRangeAny},
+						// {IP: "fd7a:115c:a1e0::100/128", Ports: tailcfg.PortRangeAny},
 						{IP: "128.0.0.0/3", Ports: tailcfg.PortRangeAny},
 						{IP: "160.0.0.0/5", Ports: tailcfg.PortRangeAny},
 						{IP: "168.0.0.0/6", Ports: tailcfg.PortRangeAny},
@@ -881,7 +895,7 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.100"),
 				IPv6: ap("fd7a:115c:a1e0::100"),
-				User: types.User{Name: "user100@"},
+				User: users[3],
 				Hostinfo: &tailcfg.Hostinfo{
 					RoutableIPs: []netip.Prefix{netip.MustParsePrefix("8.0.0.0/16"), netip.MustParsePrefix("16.0.0.0/16")},
 				},
@@ -890,12 +904,12 @@ func TestReduceFilterRules(t *testing.T) {
 				&types.Node{
 					IPv4: ap("100.64.0.2"),
 					IPv6: ap("fd7a:115c:a1e0::2"),
-					User: types.User{Name: "user2@"},
+					User: users[2],
 				},
 				&types.Node{
 					IPv4: ap("100.64.0.1"),
 					IPv6: ap("fd7a:115c:a1e0::1"),
-					User: types.User{Name: "user1@"},
+					User: users[1],
 				},
 			},
 			want: []tailcfg.FilterRule{
@@ -969,7 +983,7 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.100"),
 				IPv6: ap("fd7a:115c:a1e0::100"),
-				User: types.User{Name: "user100@"},
+				User: users[3],
 				Hostinfo: &tailcfg.Hostinfo{
 					RoutableIPs: []netip.Prefix{netip.MustParsePrefix("8.0.0.0/8"), netip.MustParsePrefix("16.0.0.0/8")},
 				},
@@ -978,12 +992,12 @@ func TestReduceFilterRules(t *testing.T) {
 				&types.Node{
 					IPv4: ap("100.64.0.2"),
 					IPv6: ap("fd7a:115c:a1e0::2"),
-					User: types.User{Name: "user2@"},
+					User: users[2],
 				},
 				&types.Node{
 					IPv4: ap("100.64.0.1"),
 					IPv6: ap("fd7a:115c:a1e0::1"),
-					User: types.User{Name: "user1@"},
+					User: users[1],
 				},
 			},
 			want: []tailcfg.FilterRule{
@@ -1046,7 +1060,7 @@ func TestReduceFilterRules(t *testing.T) {
 			node: &types.Node{
 				IPv4: ap("100.64.0.100"),
 				IPv6: ap("fd7a:115c:a1e0::100"),
-				User: types.User{Name: "user100@"},
+				User: users[3],
 				Hostinfo: &tailcfg.Hostinfo{
 					RoutableIPs: []netip.Prefix{netip.MustParsePrefix("172.16.0.0/24")},
 				},
@@ -1056,7 +1070,7 @@ func TestReduceFilterRules(t *testing.T) {
 				&types.Node{
 					IPv4: ap("100.64.0.1"),
 					IPv6: ap("fd7a:115c:a1e0::1"),
-					User: types.User{Name: "user1@"},
+					User: users[1],
 				},
 			},
 			want: []tailcfg.FilterRule{
@@ -1090,22 +1104,19 @@ func TestReduceFilterRules(t *testing.T) {
 			filterV1, _ := polV1.CompileFilterRules(
 				append(tt.peers, tt.node),
 			)
-			polV2, err := PolicyFromBytes([]byte(tt.pol))
+			pm, err := NewPolicyManager([]byte(tt.pol), users, append(tt.peers, tt.node))
 			if err != nil {
 				t.Fatalf("parsing policy: %s", err)
 			}
-			filterV2, _ := polV2.CompileFilterRules(
-				append(tt.peers, tt.node),
-			)
 
-			if diff := cmp.Diff(filterV1, filterV2); diff != "" {
+			if diff := cmp.Diff(filterV1, pm.Filter()); diff != "" {
-				log.Trace().Interface("got", filterV2).Msg("result")
+				log.Trace().Interface("got", pm.Filter()).Msg("result")
 				t.Errorf("TestReduceFilterRules() unexpected diff between v1 and v2 (-want +got):\n%s", diff)
 			}
 
 			// TODO(kradalby): Move this from v1, or
 			// rewrite.
-			filterV2 = policy.ReduceFilterRules(tt.node, filterV2)
+			filterV2 := policy.ReduceFilterRules(tt.node, pm.Filter())
 
 			if diff := cmp.Diff(tt.want, filterV2); diff != "" {
 				log.Trace().Interface("got", filterV2).Msg("result")

hscontrol/policyv2/policy.go

@@ -0,0 +1,80 @@
+package policyv2
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/juanfont/headscale/hscontrol/types"
+	"tailscale.com/tailcfg"
+)
+
+type PolicyManager struct {
+	mu    sync.Mutex
+	pol   *Policy
+	users []types.User
+	nodes types.Nodes
+
+	filter []tailcfg.FilterRule
+
+	// TODO(kradalby): Implement SSH policy
+	sshPolicy *tailcfg.SSHPolicy
+}
+
+// NewPolicyManager creates a new PolicyManager from a policy file and a list of users and nodes.
+// It returns an error if the policy file is invalid.
+// The policy manager will update the filter rules based on the users and nodes.
+func NewPolicyManager(b []byte, users []types.User, nodes types.Nodes) (*PolicyManager, error) {
+	policy, err := policyFromBytes(b)
+	if err != nil {
+		return nil, fmt.Errorf("parsing policy: %w", err)
+	}
+
+	pm := PolicyManager{
+		pol:   policy,
+		users: users,
+		nodes: nodes,
+	}
+
+	err = pm.updateLocked()
+	if err != nil {
+		return nil, err
+	}
+
+	return &pm, nil
+}
+
+// Filter returns the current filter rules for the entire tailnet.
+func (pm *PolicyManager) Filter() []tailcfg.FilterRule {
+	pm.mu.Lock()
+	defer pm.mu.Unlock()
+	return pm.filter
+}
+
+// updateLocked updates the filter rules based on the current policy and nodes.
+// It must be called with the lock held.
+func (pm *PolicyManager) updateLocked() error {
+	filter, err := pm.pol.CompileFilterRules(pm.users, pm.nodes)
+	if err != nil {
+		return fmt.Errorf("compiling filter rules: %w", err)
+	}
+
+	pm.filter = filter
+
+	return nil
+}
+
+// SetUsers updates the users in the policy manager and updates the filter rules.
+func (pm *PolicyManager) SetUsers(users []types.User) error {
+	pm.mu.Lock()
+	defer pm.mu.Unlock()
+	pm.users = users
+	return pm.updateLocked()
+}
+
+// SetNodes updates the nodes in the policy manager and updates the filter rules.
+func (pm *PolicyManager) SetNodes(nodes types.Nodes) error {
+	pm.mu.Lock()
+	defer pm.mu.Unlock()
+	pm.nodes = nodes
+	return pm.updateLocked()
+}

hscontrol/policyv2/policy_test.go

@@ -0,0 +1,58 @@
+package policyv2
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/juanfont/headscale/hscontrol/types"
+	"github.com/stretchr/testify/require"
+	"gorm.io/gorm"
+	"tailscale.com/tailcfg"
+)
+
+func node(name, ipv4, ipv6 string, user types.User, hostinfo *tailcfg.Hostinfo) *types.Node {
+	return &types.Node{
+		ID:       0,
+		Hostname: name,
+		IPv4:     ap(ipv4),
+		IPv6:     ap(ipv6),
+		User:     user,
+		UserID:   user.ID,
+		Hostinfo: hostinfo,
+	}
+}
+
+func TestPolicyManager(t *testing.T) {
+	users := types.Users{
+		{Model: gorm.Model{ID: 1}, Name: "testuser", Email: "testuser@headscale.net"},
+		{Model: gorm.Model{ID: 2}, Name: "otheruser", Email: "otheruser@headscale.net"},
+	}
+
+	tests := []struct {
+		name       string
+		pol        string
+		nodes      types.Nodes
+		wantFilter []tailcfg.FilterRule
+	}{
+		{
+			name:       "empty-policy",
+			pol:        "{}",
+			nodes:      types.Nodes{},
+			wantFilter: nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			pm, err := NewPolicyManager([]byte(tt.pol), users, tt.nodes)
+			require.NoError(t, err)
+
+			filter := pm.Filter()
+			if diff := cmp.Diff(filter, tt.wantFilter); diff != "" {
+				t.Errorf("Filter() mismatch (-want +got):\n%s", diff)
+			}
+
+			// TODO(kradalby): Test SSH Policy
+		})
+	}
+}

hscontrol/policyv2/types.go

@@ -8,6 +8,7 @@ import (
 	"net/netip"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/juanfont/headscale/hscontrol/types"
 	"github.com/juanfont/headscale/hscontrol/util"
@@ -64,7 +65,7 @@ func (a Asterix) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-func (a Asterix) Resolve(_ *Policy, nodes types.Nodes) (*netipx.IPSet, error) {
+func (a Asterix) Resolve(_ *Policy, _ types.Users, nodes types.Nodes) (*netipx.IPSet, error) {
 	var ips netipx.IPSetBuilder
 
 	ips.AddPrefix(tsaddr.AllIPv4())
@@ -99,15 +100,47 @@ func (u Username) CanBeTagOwner() bool {
 	return true
 }
 
-func (u Username) Resolve(_ *Policy, nodes types.Nodes) (*netipx.IPSet, error) {
+func (u Username) resolveUser(users types.Users) (*types.User, error) {
+	var potentialUsers types.Users
+	for _, user := range users {
+		if user.ProviderIdentifier == string(u) {
+			potentialUsers = append(potentialUsers, user)
+
+			break
+		}
+		if user.Email == string(u) {
+			potentialUsers = append(potentialUsers, user)
+		}
+		if user.Name == string(u) {
+			potentialUsers = append(potentialUsers, user)
+		}
+	}
+
+	if len(potentialUsers) > 1 {
+		return nil, fmt.Errorf("unable to resolve user identifier to distinct: %s matched multiple %s", u, potentialUsers)
+	} else if len(potentialUsers) == 0 {
+		return nil, fmt.Errorf("unable to resolve user identifier, no user found: %s not in %s", u, users)
+	}
+
+	user := potentialUsers[0]
+
+	return &user, nil
+}
+
+func (u Username) Resolve(_ *Policy, users types.Users, nodes types.Nodes) (*netipx.IPSet, error) {
 	var ips netipx.IPSetBuilder
 
+	user, err := u.resolveUser(users)
+	if err != nil {
+		return nil, err
+	}
+
 	for _, node := range nodes {
 		if node.IsTagged() {
 			continue
 		}
 
-		if node.User.Username() == string(u) {
+		if node.User.ID == user.ID {
 			node.AppendToIPSet(&ips)
 		}
 	}
@@ -137,11 +170,11 @@ func (g Group) CanBeTagOwner() bool {
 	return true
 }
 
-func (g Group) Resolve(p *Policy, nodes types.Nodes) (*netipx.IPSet, error) {
+func (g Group) Resolve(p *Policy, users types.Users, nodes types.Nodes) (*netipx.IPSet, error) {
 	var ips netipx.IPSetBuilder
 
 	for _, user := range p.Groups[g] {
-		uips, err := user.Resolve(nil, nodes)
+		uips, err := user.Resolve(nil, users, nodes)
 		if err != nil {
 			return nil, err
 		}
@@ -170,7 +203,7 @@ func (t *Tag) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-func (t Tag) Resolve(p *Policy, nodes types.Nodes) (*netipx.IPSet, error) {
+func (t Tag) Resolve(p *Policy, _ types.Users, nodes types.Nodes) (*netipx.IPSet, error) {
 	var ips netipx.IPSetBuilder
 
 	for _, node := range nodes {
@@ -197,7 +230,7 @@ func (h *Host) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-func (h Host) Resolve(p *Policy, nodes types.Nodes) (*netipx.IPSet, error) {
+func (h Host) Resolve(p *Policy, _ types.Users, nodes types.Nodes) (*netipx.IPSet, error) {
 	var ips netipx.IPSetBuilder
 
 	pref, ok := p.Hosts[h]
@@ -208,11 +241,26 @@ func (h Host) Resolve(p *Policy, nodes types.Nodes) (*netipx.IPSet, error) {
 	if err != nil {
 		return nil, err
 	}
+
+	// If the IP is a single host, look for a node to ensure we add all the IPs of
+	// the node to the IPSet.
+	appendIfNodeHasIP(nodes, &ips, pref)
 	ips.AddPrefix(netip.Prefix(pref))
 
 	return ips.IPSet()
 }
 
+func appendIfNodeHasIP(nodes types.Nodes, ips *netipx.IPSetBuilder, pref Prefix) {
+	if netip.Prefix(pref).IsSingleIP() {
+		addr := netip.Prefix(pref).Addr()
+		for _, node := range nodes {
+			if node.HasIP(addr) {
+				node.AppendToIPSet(ips)
+			}
+		}
+	}
+}
+
 type Prefix netip.Prefix
 
 func (p Prefix) Validate() error {
@@ -261,9 +309,10 @@ func (p *Prefix) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-func (p Prefix) Resolve(_ *Policy, _ types.Nodes) (*netipx.IPSet, error) {
+func (p Prefix) Resolve(_ *Policy, _ types.Users, nodes types.Nodes) (*netipx.IPSet, error) {
 	var ips netipx.IPSetBuilder
 
+	appendIfNodeHasIP(nodes, &ips, p)
 	ips.AddPrefix(netip.Prefix(p))
 
 	return ips.IPSet()
@@ -296,7 +345,7 @@ func (ag *AutoGroup) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-func (ag AutoGroup) Resolve(_ *Policy, _ types.Nodes) (*netipx.IPSet, error) {
+func (ag AutoGroup) Resolve(_ *Policy, _ types.Users, _ types.Nodes) (*netipx.IPSet, error) {
 	switch ag {
 	case AutoGroupInternet:
 		return theInternet(), nil
@@ -308,7 +357,7 @@ func (ag AutoGroup) Resolve(_ *Policy, _ types.Nodes) (*netipx.IPSet, error) {
 type Alias interface {
 	Validate() error
 	UnmarshalJSON([]byte) error
-	Resolve(*Policy, types.Nodes) (*netipx.IPSet, error)
+	Resolve(*Policy, types.Users, types.Nodes) (*netipx.IPSet, error)
 }
 
 type AliasWithPorts struct {
@@ -428,11 +477,11 @@ func (a *Aliases) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-func (a Aliases) Resolve(p *Policy, nodes types.Nodes) (*netipx.IPSet, error) {
+func (a Aliases) Resolve(p *Policy, users types.Users, nodes types.Nodes) (*netipx.IPSet, error) {
 	var ips netipx.IPSetBuilder
 
 	for _, alias := range a {
-		aips, err := alias.Resolve(p, nodes)
+		aips, err := alias.Resolve(p, users, nodes)
 		if err != nil {
 			return nil, err
 		}
@@ -530,10 +579,67 @@ type Policy struct {
 	TagOwners     TagOwners     `json:"tagOwners"`
 	ACLs          []ACL         `json:"acls"`
 	AutoApprovers AutoApprovers `json:"autoApprovers"`
-	// SSHs          []SSH         `json:"ssh"`
+	SSHs          []SSH         `json:"ssh"`
 }
 
-func PolicyFromBytes(b []byte) (*Policy, error) {
+// SSH controls who can ssh into which machines.
+type SSH struct {
+	Action       string        `json:"action"`
+	Sources      SSHSrcAliases `json:"src"`
+	Destinations SSHDstAliases `json:"dst"`
+	Users        []SSHUser     `json:"users"`
+	CheckPeriod  time.Duration `json:"checkPeriod,omitempty"`
+}
+
+// SSHSrcAliases is a list of aliases that can be used as sources in an SSH rule.
+// It can be a list of usernames, groups, tags or autogroups.
+type SSHSrcAliases []Alias
+
+func (a *SSHSrcAliases) UnmarshalJSON(b []byte) error {
+	var aliases []AliasEnc
+	err := json.Unmarshal(b, &aliases)
+	if err != nil {
+		return err
+	}
+
+	*a = make([]Alias, len(aliases))
+	for i, alias := range aliases {
+		switch alias.Alias.(type) {
+		case *Username, *Group, *Tag, *AutoGroup:
+			(*a)[i] = alias.Alias
+		default:
+			return fmt.Errorf("type %T not supported", alias.Alias)
+		}
+	}
+	return nil
+}
+
+// SSHDstAliases is a list of aliases that can be used as destinations in an SSH rule.
+// It can be a list of usernames, tags or autogroups.
+type SSHDstAliases []Alias
+
+func (a *SSHDstAliases) UnmarshalJSON(b []byte) error {
+	var aliases []AliasEnc
+	err := json.Unmarshal(b, &aliases)
+	if err != nil {
+		return err
+	}
+
+	*a = make([]Alias, len(aliases))
+	for i, alias := range aliases {
+		switch alias.Alias.(type) {
+		case *Username, *Tag, *AutoGroup:
+			(*a)[i] = alias.Alias
+		default:
+			return fmt.Errorf("type %T not supported", alias.Alias)
+		}
+	}
+	return nil
+}
+
+type SSHUser string
+
+func policyFromBytes(b []byte) (*Policy, error) {
 	var policy Policy
 	ast, err := hujson.Parse(b)
 	if err != nil {

hscontrol/policyv2/types_test.go

@@ -173,7 +173,7 @@ func TestUnmarshalPolicy(t *testing.T) {
 						Destinations: []AliasWithPorts{
 							{
 								Alias: ptr.To(Username("otheruser@headscale.net")),
-								Ports: []tailcfg.PortRange{tailcfg.PortRange{First: 80, Last: 80}},
+								Ports: []tailcfg.PortRange{{First: 80, Last: 80}},
 							},
 						},
 					},
@@ -186,7 +186,7 @@ func TestUnmarshalPolicy(t *testing.T) {
 						Destinations: []AliasWithPorts{
 							{
 								Alias: gp("group:other"),
-								Ports: []tailcfg.PortRange{tailcfg.PortRange{First: 80, Last: 80}},
+								Ports: []tailcfg.PortRange{{First: 80, Last: 80}},
 							},
 						},
 					},
@@ -199,7 +199,7 @@ func TestUnmarshalPolicy(t *testing.T) {
 						Destinations: []AliasWithPorts{
 							{
 								Alias: pp("100.101.102.104/32"),
-								Ports: []tailcfg.PortRange{tailcfg.PortRange{First: 80, Last: 80}},
+								Ports: []tailcfg.PortRange{{First: 80, Last: 80}},
 							},
 						},
 					},
@@ -212,7 +212,7 @@ func TestUnmarshalPolicy(t *testing.T) {
 						Destinations: []AliasWithPorts{
 							{
 								Alias: pp("172.16.0.0/16"),
-								Ports: []tailcfg.PortRange{tailcfg.PortRange{First: 80, Last: 80}},
+								Ports: []tailcfg.PortRange{{First: 80, Last: 80}},
 							},
 						},
 					},
@@ -225,7 +225,7 @@ func TestUnmarshalPolicy(t *testing.T) {
 						Destinations: []AliasWithPorts{
 							{
 								Alias: hp("host-1"),
-								Ports: []tailcfg.PortRange{tailcfg.PortRange{First: 80, Last: 88}},
+								Ports: []tailcfg.PortRange{{First: 80, Last: 88}},
 							},
 						},
 					},
@@ -239,8 +239,8 @@ func TestUnmarshalPolicy(t *testing.T) {
 							{
 								Alias: tp("tag:user"),
 								Ports: []tailcfg.PortRange{
-									tailcfg.PortRange{First: 80, Last: 80},
+									{First: 80, Last: 80},
-									tailcfg.PortRange{First: 443, Last: 443},
+									{First: 443, Last: 443},
 								},
 							},
 						},
@@ -255,7 +255,7 @@ func TestUnmarshalPolicy(t *testing.T) {
 							{
 								Alias: agp("autogroup:internet"),
 								Ports: []tailcfg.PortRange{
-									tailcfg.PortRange{First: 80, Last: 80},
+									{First: 80, Last: 80},
 								},
 							},
 						},
@@ -341,7 +341,7 @@ func TestUnmarshalPolicy(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			policy, err := PolicyFromBytes([]byte(tt.input))
+			policy, err := policyFromBytes([]byte(tt.input))
 			// TODO(kradalby): This error checking is broken,
 			// but so is my brain, #longflight
 			if err == nil {
@@ -538,7 +538,9 @@ func TestResolvePolicy(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			ips, err := tt.toResolve.Resolve(tt.pol, tt.nodes)
+			ips, err := tt.toResolve.Resolve(tt.pol,
+				types.Users{},
+				tt.nodes)
 			if err != nil {
 				t.Fatalf("failed to resolve: %s", err)
 			}

hscontrol/types/node.go

@@ -135,6 +135,16 @@ func (node *Node) IPs() []netip.Addr {
 	return ret
 }
 
+// HasIP reports if a node has a given IP address.
+func (node *Node) HasIP(i netip.Addr) bool {
+	for _, ip := range node.IPs() {
+		if ip.Compare(i) == 0 {
+			return true
+		}
+	}
+	return false
+}
+
 // IsTagged reports if a device is tagged
 // and therefore should not be treated as a
 // user owned device.

hscontrol/types/users.go

@@ -2,7 +2,9 @@ package types
 
 import (
 	"cmp"
+	"fmt"
 	"strconv"
+	"strings"
 
 	v1 "github.com/juanfont/headscale/gen/go/headscale/v1"
 	"github.com/juanfont/headscale/hscontrol/util"
@@ -13,6 +15,19 @@ import (
 
 type UserID uint64
 
+type Users []User
+
+func (u Users) String() string {
+	var sb strings.Builder
+	sb.WriteString("[ ")
+	for _, user := range u {
+		fmt.Fprintf(&sb, "%d: %s, ", user.ID, user.Name)
+	}
+	sb.WriteString(" ]")
+
+	return sb.String()
+}
+
 // User is the way Headscale implements the concept of users in Tailscale
 //
 // At the end of the day, users in Tailscale are some kind of 'bubbles' or users