From db44a98a2dd33444cdfb43a35259f76a9f9e9587 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Sun, 4 Mar 2018 11:53:52 -0800
Subject: [PATCH] agent/consul: Intention.Get ACLs

---
 agent/consul/acl.go                     | 30 +++++++++
 agent/consul/intention_endpoint.go      | 11 ++-
 agent/consul/intention_endpoint_test.go | 90 +++++++++++++++++++++++++
 3 files changed, 130 insertions(+), 1 deletion(-)

diff --git a/agent/consul/acl.go b/agent/consul/acl.go
index 1e95e62e4..ce3282b40 100644
--- a/agent/consul/acl.go
+++ b/agent/consul/acl.go
@@ -454,6 +454,33 @@ func (f *aclFilter) filterCoordinates(coords *structs.Coordinates) {
 	*coords = c
 }
 
+// filterIntentions is used to filter intentions based on ACL rules.
+// We prune entries the user doesn't have access to, and we redact any tokens
+// if the user doesn't have a management token.
+func (f *aclFilter) filterIntentions(ixns *structs.Intentions) {
+	// Management tokens can see everything with no filtering.
+	if f.acl.ACLList() {
+		return
+	}
+
+	// Otherwise, we need to see what the token has access to.
+	ret := make(structs.Intentions, 0, len(*ixns))
+	for _, ixn := range *ixns {
+		// If no prefix ACL applies to this then filter it, since
+		// we know at this point the user doesn't have a management
+		// token, otherwise see what the policy says.
+		prefix, ok := ixn.GetACLPrefix()
+		if !ok || !f.acl.IntentionRead(prefix) {
+			f.logger.Printf("[DEBUG] consul: dropping intention %q from result due to ACLs", ixn.ID)
+			continue
+		}
+
+		ret = append(ret, ixn)
+	}
+
+	*ixns = ret
+}
+
 // filterNodeDump is used to filter through all parts of a node dump and
 // remove elements the provided ACL token cannot access.
 func (f *aclFilter) filterNodeDump(dump *structs.NodeDump) {
@@ -598,6 +625,9 @@ func (s *Server) filterACL(token string, subj interface{}) error {
 	case *structs.IndexedHealthChecks:
 		filt.filterHealthChecks(&v.HealthChecks)
 
+	case *structs.IndexedIntentions:
+		filt.filterIntentions(&v.Intentions)
+
 	case *structs.IndexedNodeDump:
 		filt.filterNodeDump(&v.Dump)
 
diff --git a/agent/consul/intention_endpoint.go b/agent/consul/intention_endpoint.go
index 2a409dcbe..568446d73 100644
--- a/agent/consul/intention_endpoint.go
+++ b/agent/consul/intention_endpoint.go
@@ -168,7 +168,16 @@ func (s *Intention) Get(
 			reply.Index = index
 			reply.Intentions = structs.Intentions{ixn}
 
-			// TODO: acl filtering
+			// Filter
+			if err := s.srv.filterACL(args.Token, reply); err != nil {
+				return err
+			}
+
+			// If ACLs prevented any responses, error
+			if len(reply.Intentions) == 0 {
+				s.srv.logger.Printf("[WARN] consul.intention: Request to get intention '%s' denied due to ACLs", args.IntentionID)
+				return acl.ErrPermissionDenied
+			}
 
 			return nil
 		},
diff --git a/agent/consul/intention_endpoint_test.go b/agent/consul/intention_endpoint_test.go
index fd76bbb78..67c2a07d0 100644
--- a/agent/consul/intention_endpoint_test.go
+++ b/agent/consul/intention_endpoint_test.go
@@ -654,6 +654,96 @@ service "foo" {
 	}
 }
 
+// Test reading with ACLs
+func TestIntentionGet_acl(t *testing.T) {
+	t.Parallel()
+	dir1, s1 := testServerWithConfig(t, func(c *Config) {
+		c.ACLDatacenter = "dc1"
+		c.ACLMasterToken = "root"
+		c.ACLDefaultPolicy = "deny"
+	})
+	defer os.RemoveAll(dir1)
+	defer s1.Shutdown()
+	codec := rpcClient(t, s1)
+	defer codec.Close()
+
+	testrpc.WaitForLeader(t, s1.RPC, "dc1")
+
+	// Create an ACL with service write permissions. This will grant
+	// intentions read.
+	var token string
+	{
+		var rules = `
+service "foo" {
+	policy = "write"
+}`
+
+		req := structs.ACLRequest{
+			Datacenter: "dc1",
+			Op:         structs.ACLSet,
+			ACL: structs.ACL{
+				Name:  "User token",
+				Type:  structs.ACLTypeClient,
+				Rules: rules,
+			},
+			WriteRequest: structs.WriteRequest{Token: "root"},
+		}
+		if err := msgpackrpc.CallWithCodec(codec, "ACL.Apply", &req, &token); err != nil {
+			t.Fatalf("err: %v", err)
+		}
+	}
+
+	// Setup a basic record to create
+	ixn := structs.IntentionRequest{
+		Datacenter: "dc1",
+		Op:         structs.IntentionOpCreate,
+		Intention:  structs.TestIntention(t),
+	}
+	ixn.Intention.DestinationName = "foobar"
+	ixn.WriteRequest.Token = "root"
+
+	// Create
+	var reply string
+	if err := msgpackrpc.CallWithCodec(codec, "Intention.Apply", &ixn, &reply); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	ixn.Intention.ID = reply
+
+	// Read without token should be error
+	{
+		req := &structs.IntentionQueryRequest{
+			Datacenter:  "dc1",
+			IntentionID: ixn.Intention.ID,
+		}
+
+		var resp structs.IndexedIntentions
+		err := msgpackrpc.CallWithCodec(codec, "Intention.Get", req, &resp)
+		if !acl.IsErrPermissionDenied(err) {
+			t.Fatalf("bad: %v", err)
+		}
+		if len(resp.Intentions) != 0 {
+			t.Fatalf("bad: %v", resp)
+		}
+	}
+
+	// Read with token should work
+	{
+		req := &structs.IntentionQueryRequest{
+			Datacenter:   "dc1",
+			IntentionID:  ixn.Intention.ID,
+			QueryOptions: structs.QueryOptions{Token: token},
+		}
+
+		var resp structs.IndexedIntentions
+		if err := msgpackrpc.CallWithCodec(codec, "Intention.Get", req, &resp); err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if len(resp.Intentions) != 1 {
+			t.Fatalf("bad: %v", resp)
+		}
+	}
+}
+
 func TestIntentionList(t *testing.T) {
 	t.Parallel()