budibase/packages/server/src/middleware/authorized.js

const {
  getUserRoleHierarchy,
  getRequiredResourceRole,
  BUILTIN_ROLE_IDS,
} = require("@budibase/backend-core/roles")
const {
  PermissionTypes,
  doesHaveBasePermission,
} = require("@budibase/backend-core/permissions")
const builderMiddleware = require("./builder")
const { isWebhookEndpoint } = require("./utils")
const { buildCsrfMiddleware } = require("@budibase/backend-core/auth")
const { getAppId } = require("@budibase/backend-core/context")

function hasResource(ctx) {
  return ctx.resourceId != null
}

const csrf = buildCsrfMiddleware()

/**
 * Apply authorization to the requested resource:
 * - If this is a builder resource the user must be a builder.
 * - Builders can access all resources.
 * - Otherwise the user must have the required role.
 */
const checkAuthorized = async (ctx, resourceRoles, permType, permLevel) => {
  // check if this is a builder api and the user is not a builder
  const isBuilder = ctx.user && ctx.user.builder && ctx.user.builder.global
  const isBuilderApi = permType === PermissionTypes.BUILDER
  if (isBuilderApi && !isBuilder) {
    return ctx.throw(403, "Not Authorized")
  }

  // check for resource authorization
  if (!isBuilder) {
    await checkAuthorizedResource(ctx, resourceRoles, permType, permLevel)
  }
}

const checkAuthorizedResource = async (
  ctx,
  resourceRoles,
  permType,
  permLevel
) => {
  // get the user's roles
  const roleId = ctx.roleId || BUILTIN_ROLE_IDS.PUBLIC
  const userRoles = await getUserRoleHierarchy(roleId, {
    idOnly: false,
  })
  const permError = "User does not have permission"
  // check if the user has the required role
  if (resourceRoles.length > 0) {
    // deny access if the user doesn't have the required resource role
    const found = userRoles.find(role => resourceRoles.indexOf(role._id) !== -1)
    if (!found) {
      ctx.throw(403, permError)
    }
    // fallback to the base permissions when no resource roles are found
  } else if (!doesHaveBasePermission(permType, permLevel, userRoles)) {
    ctx.throw(403, permError)
  }
}

module.exports =
  (permType, permLevel = null) =>
  async (ctx, next) => {
    // webhooks don't need authentication, each webhook unique
    // also internal requests (between services) don't need authorized
    if (isWebhookEndpoint(ctx) || ctx.internal) {
      return next()
    }

    if (!ctx.user) {
      return ctx.throw(403, "No user info found")
    }

    // check general builder stuff, this middleware is a good way
    // to find API endpoints which are builder focused
    await builderMiddleware(ctx, permType)

    // get the resource roles
    let resourceRoles = []
    const appId = getAppId()
    if (appId && hasResource(ctx)) {
      resourceRoles = await getRequiredResourceRole(permLevel, ctx)
    }

    // if the resource is public, proceed
    const isPublicResource = resourceRoles.includes(BUILTIN_ROLE_IDS.PUBLIC)
    if (isPublicResource) {
      return next()
    }

    // check authenticated
    if (!ctx.isAuthenticated) {
      return ctx.throw(403, "Session not authenticated")
    }

    // check authorized
    await checkAuthorized(ctx, resourceRoles, permType, permLevel)

    // csrf protection
    return csrf(ctx, next)
  }