functions with IAM least privilege

functions: {
    UserLogin: {
        handler: `src/handler.main`,

        environment: {
            USERS_TABLE: { Ref: 'UsersTable' },
        },
        iamRoleStatements: [
            {
                Effect: 'Allow',
                Action: 'dynamodb:GetItem',
                Resource: { 'Fn::GetAtt': ['UsersTable', 'Arn'] },
            },
            {
                Effect: 'Allow',
                Action: 'dynamodb:PutItem',
                Resource: { 'Fn::GetAtt': ['CompaniesTable', 'Arn'] },
            },
        ],
    }
},