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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Aleksa Sarai <cyphar@cyphar.com>
Cc: Eric Biederman <ebiederm@xmission.com>,
	Christian Brauner <christian@brauner.io>,
	Jeff Layton <jlayton@kernel.org>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
	David Howells <dhowells@redhat.com>, Jann Horn <jannh@google.com>,
	Tycho Andersen <tycho@tycho.ws>,
	David Drysdale <drysdale@google.com>,
	dev@opencontainers.org, containers@lists.linux-foundation.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH v3 1/3] namei: implement O_BENEATH-style AT_* flags
Date: Sat, 13 Oct 2018 09:05:11 +0100	[thread overview]
Message-ID: <20181013080511.GT32577@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20181013073319.GS32577@ZenIV.linux.org.uk>

On Sat, Oct 13, 2018 at 08:33:19AM +0100, Al Viro wrote:

> Pardon me, but... huh?  The reason for your two calls of dirfd_path_init() is,
> AFAICS, the combination of absolute pathname with both LOOKUP_XDEV and
> LOOKUP_BENEATH at the same time.  That combination is treated as if the pathname
> had been relative.  Note that LOOKUP_BENEATH alone is ignored for absolute ones
> (and with a good reason - it's a no-op on path_init() level in that case).
> 
> What the hell?  It complicates your code and doesn't seem to provide any benefits
> whatsoever -- you could bloody well have passed the relative pathname to start with.
> 
> IDGI...  Without that kludge it becomes simply "do as we currently do for absolute
> pathnames, call dirfd_path_init() for relative ones".  And I would argue that
> taking LOOKUP_BENEATH handling out of dirfd_path_init() into path_init() (relative)
> case would be a good idea.
> 
> As it is, the logics is very hard to follow.

	... and it fails on LOOKUP_BENEATH anyway.  Egads...  So that's for your
LOOKUP_CHROOT ;-/  IMO that's awful, especially with the way you've spread those
LOOKUP_CHROOT cases between these two.

	Why not simply have O_THISROOT pick root by dirfd and call file_open_root()?
And if something wants it for stat(), etc. just have them use it combined with
O_PATH and pass the result to ...at()...

  parent reply	other threads:[~2018-10-13  8:05 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-09  7:02 [PATCH v3 0/3] namei: implement various lookup restriction AT_* flags Aleksa Sarai
2018-10-09  7:02 ` Aleksa Sarai
2018-10-09  7:02 ` [PATCH v3 1/3] namei: implement O_BENEATH-style " Aleksa Sarai
2018-10-09  7:02   ` Aleksa Sarai
2018-10-13  7:33   ` Al Viro
2018-10-13  7:33     ` Al Viro
2018-10-13  8:05     ` Al Viro [this message]
2018-10-13  8:05       ` Al Viro
2018-10-13  8:20       ` Aleksa Sarai
2018-10-13  8:20         ` Aleksa Sarai
2018-10-13  8:09     ` Aleksa Sarai
2018-10-13  8:09       ` Aleksa Sarai
2018-10-09  7:02 ` [PATCH v3 2/3] namei: implement AT_THIS_ROOT chroot-like path resolution Aleksa Sarai
2018-10-09  7:02   ` Aleksa Sarai
2018-10-09  7:02 ` [PATCH v3 3/3] namei: aggressively check for nd->root escape on ".." resolution Aleksa Sarai
2018-10-09  7:02   ` Aleksa Sarai
2018-10-09 15:19   ` Jann Horn
2018-10-09 15:19     ` Jann Horn
2018-10-09 15:37     ` Aleksa Sarai
2018-10-09 15:37       ` Aleksa Sarai
2018-10-09 16:46       ` Jann Horn
2018-10-09 16:46         ` Jann Horn
2018-10-13  8:22       ` Al Viro
2018-10-13  8:22         ` Al Viro
2018-10-13  8:53         ` Aleksa Sarai
2018-10-13  8:53           ` Aleksa Sarai
2018-10-13  9:04           ` Al Viro
2018-10-13  9:04             ` Al Viro
2018-10-13  9:27             ` Aleksa Sarai
2018-10-13  9:27               ` Aleksa Sarai
2018-10-17 15:23 ` [PATCH v3 0/3] namei: implement various lookup restriction AT_* flags Aleksa Sarai
2018-10-17 15:23   ` Aleksa Sarai

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