fix: prevent write:groups from self-promoting

server/core/auth.js

@@ -287,6 +287,34 @@ module.exports = {
   },
 
   /**
+   * Check for exclusive permissions (contain any X permission(s) but not any Y permission(s))
+   *
+   * @param {User} user
+   * @param {Array<String>} includePermissions
+   * @param {Array<String>} excludePermissions
+   */
+  checkExclusiveAccess(user, includePermissions = [], excludePermissions = []) {
+    const userPermissions = user.permissions ? user.permissions : user.getGlobalPermissions()
+
+    // System Admin
+    if (userPermissions.includes('manage:system')) {
+      return true
+    }
+
+    // Check Inclusion Permissions
+    if (_.intersection(userPermissions, includePermissions).length < 1) {
+      return false
+    }
+
+    // Check Exclusion Permissions
+    if (_.intersection(userPermissions, excludePermissions).length > 0) {
+      return false
+    }
+
+    return true
+  },
+
+  /**
    * Check and apply Page Rule specificity
    *
    * @access private

server/graph/resolvers/group.js

 const graphHelper = require('../../helpers/graph')
 const safeRegex = require('safe-regex')
 const _ = require('lodash')
+const gql = require('graphql')
 
 /* global WIKI */
 
-const gql = require('graphql')
-
 module.exports = {
   Query: {
-    async groups() { return {} }
+    async groups () { return {} }
   },
   Mutation: {
-    async groups() { return {} }
+    async groups () { return {} }
   },
   GroupQuery: {
-    async list(obj, args, context, info) {
+    /**
+     * FETCH ALL GROUPS
+     */
+    async list () {
       return WIKI.models.groups.query().select(
         'groups.*',
         WIKI.models.groups.relatedQuery('users').count().as('userCount')
       )
     },
-    async single(obj, args, context, info) {
+    /**
+     * FETCH A SINGLE GROUP
+     */
+    async single(obj, args) {
       return WIKI.models.groups.query().findById(args.id)
     }
   },
   GroupMutation: {
-    async assignUser(obj, args) {
+    /**
+     * ASSIGN USER TO GROUP
+     */
+    async assignUser (obj, args, { req }) {
+      // Check for guest user
+      if (args.userId === 2) {
+        throw new gql.GraphQLError('Cannot assign the Guest user to a group.')
+      }
+
+      // Check for valid group
       const grp = await WIKI.models.groups.query().findById(args.groupId)
       if (!grp) {
         throw new gql.GraphQLError('Invalid Group ID')
       }
+
+      // Check assigned permissions for write:groups
+      if (
+        WIKI.auth.checkExclusiveAccess(req.user, ['write:groups'], ['manage:groups', 'manage:system']) &&
+        grp.permissions.some(p => {
+          const resType = _.last(p.split(':'))
+          return ['users', 'groups', 'navigation', 'theme', 'api', 'system'].includes(resType)
+        })
+      ) {
+        throw new gql.GraphQLError('You are not authorized to assign a user to this elevated group.')
+      }
+
+      // Check for valid user
       const usr = await WIKI.models.users.query().findById(args.userId)
       if (!usr) {
         throw new gql.GraphQLError('Invalid User ID')
       }
+
+      // Check for existing relation
       const relExist = await WIKI.models.knex('userGroups').where({
         userId: args.userId,
         groupId: args.groupId
@@ -41,8 +70,11 @@ module.exports = {
       if (relExist) {
         throw new gql.GraphQLError('User is already assigned to group.')
       }
+
+      // Assign user to group
       await grp.$relatedQuery('users').relate(usr.id)
 
+      // Revoke tokens for this user
       WIKI.auth.revokeUserTokens({ id: usr.id, kind: 'u' })
       WIKI.events.outbound.emit('addAuthRevoke', { id: usr.id, kind: 'u' })
 
@@ -50,7 +82,10 @@ module.exports = {
         responseResult: graphHelper.generateSuccess('User has been assigned to group.')
       }
     },
-    async create(obj, args) {
+    /**
+     * CREATE NEW GROUP
+     */
+    async create (obj, args, { req }) {
       const group = await WIKI.models.groups.query().insertAndFetch({
         name: args.name,
         permissions: JSON.stringify(WIKI.data.groups.defaultPermissions),
@@ -64,7 +99,14 @@ module.exports = {
         group
       }
     },
-    async delete(obj, args) {
+    /**
+     * DELETE GROUP
+     */
+    async delete (obj, args) {
+      if (args.id === 1 || args.id === 2) {
+        throw new gql.GraphQLError('Cannot delete this group.')
+      }
+
       await WIKI.models.groups.query().deleteById(args.id)
 
       WIKI.auth.revokeUserTokens({ id: args.id, kind: 'g' })
@@ -77,7 +119,16 @@ module.exports = {
         responseResult: graphHelper.generateSuccess('Group has been deleted.')
       }
     },
-    async unassignUser(obj, args) {
+    /**
+     * UNASSIGN USER FROM GROUP
+     */
+    async unassignUser (obj, args) {
+      if (args.userId === 2) {
+        throw new gql.GraphQLError('Cannot unassign Guest user')
+      }
+      if (args.userId === 1 && args.groupId === 1) {
+        throw new gql.GraphQLError('Cannot unassign Administrator user from Administrators group.')
+      }
       const grp = await WIKI.models.groups.query().findById(args.groupId)
       if (!grp) {
         throw new gql.GraphQLError('Invalid Group ID')
@@ -95,17 +146,34 @@ module.exports = {
         responseResult: graphHelper.generateSuccess('User has been unassigned from group.')
       }
     },
-    async update(obj, args) {
+    /**
+     * UPDATE GROUP
+     */
+    async update (obj, args, { req }) {
+      // Check for unsafe regex page rules
       if (_.some(args.pageRules, pr => {
         return pr.match === 'REGEX' && !safeRegex(pr.path)
       })) {
         throw new gql.GraphQLError('Some Page Rules contains unsafe or exponential time regex.')
       }
 
+      // Set default redirect on login value
       if (_.isEmpty(args.redirectOnLogin)) {
         args.redirectOnLogin = '/'
       }
 
+      // Check assigned permissions for write:groups
+      if (
+        WIKI.auth.checkExclusiveAccess(req.user, ['write:groups'], ['manage:groups', 'manage:system']) &&
+        args.permissions.some(p => {
+          const resType = _.last(p.split(':'))
+          return ['users', 'groups', 'navigation', 'theme', 'api', 'system'].includes(resType)
+        })
+      ) {
+        throw new gql.GraphQLError('You are not authorized to manage this group or assign these permissions.')
+      }
+
+      // Update group
       await WIKI.models.groups.query().patch({
         name: args.name,
         redirectOnLogin: args.redirectOnLogin,
@@ -113,9 +181,11 @@ module.exports = {
         pageRules: JSON.stringify(args.pageRules)
       }).where('id', args.id)
 
+      // Revoke tokens for this group
       WIKI.auth.revokeUserTokens({ id: args.id, kind: 'g' })
       WIKI.events.outbound.emit('addAuthRevoke', { id: args.id, kind: 'g' })
 
+      // Reload group permissions
       await WIKI.auth.reloadGroups()
       WIKI.events.outbound.emit('reloadGroups')
 
@@ -125,7 +195,7 @@ module.exports = {
     }
   },
   Group: {
-    users(grp) {
+    users (grp) {
       return grp.$relatedQuery('users')
     }
   }