Re: [RFC PATCH v14 06/10] landlock: Add syscall implementation

[MickaÃl SalaÃn]

On 17/03/2020 17:47, Al Viro wrote:
> On Mon, Feb 24, 2020 at 05:02:11PM +0100, Mickaël Salaün wrote:
> 
>> +static int get_path_from_fd(u64 fd, struct path *path)
> 
>> +	/*
>> +	 * Only allows O_PATH FD: enable to restrict ambiant (FS) accesses
>> +	 * without requiring to open and risk leaking or misuing a FD.  Accept
>> +	 * removed, but still open directory (S_DEAD).
>> +	 */
>> +	if (!(f.file->f_mode & FMODE_PATH) || !f.file->f_path.mnt ||
> 					      ^^^^^^^^^^^^^^^^^^^
> Could you explain what that one had been be about?  The underlined
> subexpression is always false; was that supposed to check some
> condition and if so, which one?
> 

This was just to be sure that the next assignment "path->mnt =
f.file->f_path.mnt;" always creates a valid path. If this is always
true, I will remove it.