linux-kernel - Re: [patch] pipe: add support for shrinking and growing pipes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 24 May 2010 09:05:52 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	mtk.manpages@...il.com
Cc:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Miklos Szeredi <miklos@...redi.hu>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [patch] pipe: add support for shrinking and growing pipes

> The "at least" idea makes sense. So, I'd change my recommendation to:
> 
> Pass the buffer size in and out in bytes (for consistency with other
> APIs). Round the input (F_SETPIPE_SZ) value up as required by the
> implementation. For the output (F_GETPIPE_SZ) value do one of the
> following:
> a) Return the value given on input.
> b) Return the rounded up value actually used by the kernel.
> 
> I suspect (b) might be more useful: if an application cares enough
> about pipe size to want to change it, then at least some such
> applications might care to know exactly the size that the kernel used.
> (And: I can't see any downside to (b).)

b definitely, since it's the real size (plus then we don't have to track
the passed in size).

> One other comment about the interface. We have
> 
>                 if (!capable(CAP_SYS_ADMIN) && arg > pipe_max_pages)
>                         return -EINVAL;
> 
> The usual error on a capability denied is EPERM. Please change.

Right, that looks like a thinko.

I'll submit a patch changing it to bytes and the agreed API and fix this
-Eerror. Thanks for your comments and suggestions!

-- 
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/