session_rpcserver+litrpc: allow custom session with all read-only perms

litrpc/lit-sessions.proto

@@ -36,10 +36,18 @@ message AddSessionRequest {
 }
 
 message MacaroonPermission {
-    // The entity a permission grants access to.
+    // The entity a permission grants access to. If a entity is set to the
+    // "uri" keyword then the action entry should be one of the special cases
+    // described in the comment for action.
     string entity = 1;
 
-    // The action that is granted.
+    // The action that is granted. If entity is set to "uri", then action must
+    // be set to either:
+    //  - a particular URI to which access should be granted.
+    //  - a URI regex, in which case access will be granted to each URI that
+    //    matches the regex.
+    //  - the "***readonly***" keyword. This will result in the access being
+    //    granted to all read-only endpoints.
     string action = 2;
 }
 

perms/permissions_test.go

@@ -78,4 +78,10 @@ func TestMatchRegexURI(t *testing.T) {
 	uris, isRegex = m.MatchRegexURI("/poolrpc.Trader/.*")
 	require.True(t, isRegex)
 	require.Empty(t, uris)
+
+	// Assert that the read-only permission's keyword is not seen as a valid
+	// regex.
+	uris, isRegex = m.MatchRegexURI("***readonly***")
+	require.False(t, isRegex)
+	require.Empty(t, uris)
 }

session_rpcserver.go

@@ -19,6 +19,14 @@ import (
 	"gopkg.in/macaroon.v2"
 )
 
+// readOnlyAction defines the keyword that a permission action should be set to
+// when the entity is set to "uri" in order to activate the special case that
+// will result in all read-only permissions known to lit to be added to a
+// session's macaroon. The purpose of the three '*'s is to make this keyword
+// an invalid URI and an invalid regex so that it does not ever clash with the
+// other special cases.
+const readOnlyAction = "***readonly***"
+
 // sessionRpcServer is the gRPC server for the Session RPC interface.
 type sessionRpcServer struct {
 	litrpc.UnimplementedSessionsServer
@@ -126,7 +134,21 @@ func (s *sessionRpcServer) AddSession(_ context.Context,
 		return nil, err
 	}
 
-	var permissions []bakery.Op
+	// Store the entity-action permission pairs in a map in order to
+	// de-dup any repeat perms.
+	permissions := make(map[string]map[string]struct{})
+
+	// addPerm is a closure that can be used to add entity-action pairs to
+	// the permissions map.
+	addPerm := func(entity, action string) {
+		_, ok := permissions[entity]
+		if !ok {
+			permissions[entity] = make(map[string]struct{})
+		}
+
+		permissions[entity][action] = struct{}{}
+	}
+
 	switch typ {
 	// For the default session types we use empty caveats and permissions,
 	// the macaroons are baked correctly when creating the session.
@@ -144,10 +166,23 @@ func (s *sessionRpcServer) AddSession(_ context.Context,
 
 		for _, op := range req.MacaroonCustomPermissions {
 			if op.Entity != macaroons.PermissionEntityCustomURI {
-				permissions = append(permissions, bakery.Op{
-					Entity: op.Entity,
-					Action: op.Action,
-				})
+				addPerm(op.Entity, op.Action)
+
+				continue
+			}
+
+			// If the action specified was equal to the
+			// readOnlyAction keyword, then this is taken to mean
+			// that the permissions for all read-only URIs should be
+			// granted.
+			if op.Action == readOnlyAction {
+				readPerms := s.cfg.permMgr.ActivePermissions(
+					true,
+				)
+
+				for _, p := range readPerms {
+					addPerm(p.Entity, p.Action)
+				}
 
 				continue
 			}
@@ -159,12 +194,7 @@ func (s *sessionRpcServer) AddSession(_ context.Context,
 				// the matching URIs returned from the
 				// permissions' manager.
 				for _, uri := range uris {
-					permissions = append(
-						permissions, bakery.Op{
-							Entity: op.Entity,
-							Action: uri,
-						},
-					)
+					addPerm(op.Entity, uri)
 				}
 				continue
 			}
@@ -177,10 +207,7 @@ func (s *sessionRpcServer) AddSession(_ context.Context,
 					"LiT", op.Action)
 			}
 
-			permissions = append(permissions, bakery.Op{
-				Entity: op.Entity,
-				Action: op.Action,
-			})
+			addPerm(op.Entity, op.Action)
 		}
 
 	// No other types are currently supported.
@@ -189,9 +216,20 @@ func (s *sessionRpcServer) AddSession(_ context.Context,
 			"readonly and custom macaroon types supported in LiT")
 	}
 
+	// Collect the de-duped permissions.
+	var perms []bakery.Op
+	for entity, actions := range permissions {
+		for action := range actions {
+			perms = append(perms, bakery.Op{
+				Entity: entity,
+				Action: action,
+			})
+		}
+	}
+
 	sess, err := session.NewSession(
 		req.Label, typ, expiry, req.MailboxServerAddr, req.DevServer,
-		permissions, nil,
+		perms, nil,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("error creating new session: %v", err)