From: Herbert Xu <herbert@gondor.apana.org.au>
To: Jonathan Nieder <jrnieder@gmail.com>
Cc: dash@vger.kernel.org, Christoph Egger <christoph@debian.org>,
Petr Salinger <Petr.Salinger@seznam.cz>
Subject: Re: [PATCH v2] [BUILTIN] Fix "test -x" as root on FreeBSD 8
Date: Mon, 17 Nov 2014 22:49:46 +0800 [thread overview]
Message-ID: <20141117144946.GA1778@gondor.apana.org.au> (raw)
In-Reply-To: <20110927231906.GC19549@elie>
On Tue, Sep 27, 2011 at 06:19:06PM -0500, Jonathan Nieder wrote:
> POSIX.1-2008 §4.4 "File Access Permission" sayeth:
>
> If execute permission is requested, access shall be granted
> if execute permission is granted to at least one user by the
> file permission bits or by an alternate access control
> mechanism; otherwise, access shall be denied.
>
> For historical reasons, POSIX unfortunately also allows access() and
> faccessat() to return success for X_OK if the current process is
> privileged, even when the above condition is not fulfilled and actual
> execution would fail. On the affected platforms, "test -x <path>" as
> root started returning true on nonexecutable files when dash switched
> from its own emulation to the true faccessat in v0.5.7~54
> (2010-04-02).
>
> Work around this by checking the permissions bits when mode == X_OK
> and geteuid() == 0 on such platforms.
>
> Unfortunately the behavior seems to vary from one kernel version to
> another, so we cannot just check the behavior at compile time and rely
> on that. A survey of some affected kernels:
>
> - NetBSD's kernel moved to the sane semantics in 1997
> - OpenBSD's kernel made the same change in version 4.4, three years
> ago
> - FreeBSD 9's kernel fixes this but hasn't been released yet
>
> It seems safe to only apply the workaround on systems using the
> FreeBSD kernel for now, and to push for standardization on the
> expected access()/faccessat() semantics so we can drop the workaround
> altogether in a few years.
>
> To try it on other platforms, use "./configure --enable-test-workaround".
>
> Reported-by: Christoph Egger <christoph@debian.org>
> Analysis-by: Petr Salinger <Petr.Salinger@seznam.cz>
> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
This patch seems to have slipped through the cracks. Nevertheless
it is now applied.
Thanks,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
prev parent reply other threads:[~2014-11-17 14:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-26 21:16 [PATCH] [BUILTIN] Make "test -x" sane again when run as root Jonathan Nieder
2011-09-26 22:16 ` Jonathan Nieder
2011-09-27 13:45 ` Herbert Xu
2011-09-27 23:19 ` [PATCH v2] [BUILTIN] Fix "test -x" as root on FreeBSD 8 Jonathan Nieder
2014-11-17 14:49 ` Herbert Xu [this message]
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