std::unique_ptr as out argument to a function

struct cls{
    ~cls(){std::cout<<"dtor\n";}
};

void foo(cls** pp){
    *pp = new cls;
}

int main()
{
    cls* raw_ptr = 0;    
    foo(&raw_ptr);
    std::unique_ptr<cls> u_ptr{raw_ptr};
}

Is there any way to directly access the raw_pointer in the unique_ptr to pass to the function foo(cls** pp)?

Or

cls* raw_ptr = 0;    
foo(&raw_ptr);
std::unique_ptr<cls> u_ptr{raw_ptr};

Is it the only way?

Note: I cannot change the signature of the function foo.