From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [PATCH] vfs: fix linkat error for unprivileged AT_EMPTY_PATH
Date: Wed, 24 Sep 2014 20:00:58 +0100
Message-ID: <20140924190058.GE7996@ZenIV.linux.org.uk>
References: <20140924152523.GC7441@tucsk.piliscsaba.szeredi.hu>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
To: Miklos Szeredi <miklos@szeredi.hu>
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In-Reply-To: <20140924152523.GC7441@tucsk.piliscsaba.szeredi.hu>
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On Wed, Sep 24, 2014 at 05:25:23PM +0200, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi@suse.cz>
> 
> Return proper error value for linkat(..., AT_EMPTY_PATH) without enough
> privileges.
> 
> I guess ENOENT was used here, because without AT_EMPTY_PATH that's what
> we'd return for an empty path.  But it is wrong for AT_EMPTY_PATH, since we
> might not even be passing an empty path, we are simply complaining about
> lack of privs for which EPERM is the proper error.

Umm...  Are you sure that nothing in userland is checking for that
return value?  I agree that EPERM would make more sense, but...