linux-kernel - Filesystem (directory) permissions meaning difference for x86

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Message-ID: <20111109215125.7c1c3d3a@neptune.home>
Date:	Wed, 9 Nov 2011 21:51:25 +0100
From:	Bruno Prémont <bonbons@...ux-vserver.org>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Filesystem (directory) permissions meaning difference for x86_64
 and x86 for 3.1?

Hi,

On a x86_64 system I'm getting permission denied when trying to chdir()
into a directory where I have only 'x' permissions (be it with unix
permissions or with posix ACLs).
For the same layout of directory I can successfully chdir() on x86 as I
can with older kernels of 2.6 series.

In both cases the filesystem is tmpfs with support for posix ACLs and
kernel is 3.1.0.

Directory layout:
drwx--x---  3 root test   60 Nov  9 21:14 /tmp/btest
drwxrwx---  2 root test   40 Nov  9 21:14 /tmp/btest/subtest
drwxr-x---+ 3 root root   60 Nov  9 21:10 /tmp/test
drwxrwx---+ 2 root root   40 Nov  9 21:10 /tmp/test/subtest

Posix ACLs
# file: /tmp/test
# owner: root
# group: root
user::rwx
group::r-x
group:test:--x
mask::r-x
other::---

# file: test/subtest/
# owner: root
# group: root
user::rwx
group::r-x
group:test:rwx
mask::rwx
other::---

When executing as user test (with test as only group), on x86_64 I get
EPERM on chdir(X) where X is any one of the 4 directories above.

On x86 I can chdir() into the directory without issue (as expected),
and when in /tmp/test (or /tmp/btest) I get EPERM when trying to list
contents - expected as well. Under subtest I can list content.

The same results are obtained on XFS filesystem.

Any idea what's wrong?

Both test configs attached.

Bruno
Download attachment "x86.config.bz2" of type "application/x-bzip" (5162 bytes)

Download attachment "x86_64.config.bz2" of type "application/x-bzip" (3723 bytes)