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Date:   Sat, 29 Sep 2018 12:44:29 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Andy Lutomirski <luto@amacapital.net>
Cc:     Aleksa Sarai <cyphar@cyphar.com>, Jeff Layton <jlayton@kernel.org>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Arnd Bergmann <arnd@arndb.de>, Shuah Khan <shuah@kernel.org>,
        David Howells <dhowells@redhat.com>,
        Andy Lutomirski <luto@kernel.org>,
        Christian Brauner <christian@brauner.io>,
        Eric Biederman <ebiederm@xmission.com>,
        Tycho Andersen <tycho@tycho.ws>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-kselftest@vger.kernel.org, dev@opencontainers.org,
        containers@lists.linux-foundation.org
Subject: Re: [PATCH 0/3] namei: implement various scoping AT_* flags
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On Sat, Sep 29, 2018 at 09:34:24AM -0700, Andy Lutomirski wrote:
> Also, as a perhaps-silly suggestion: if you end up adding a new
> syscall, I can see a use for a mode that does the path walk but, rather
> than failing on a disallowed link, stops early and indicates where it
> stopped. Then web servers, samba, etc can more efficiently implement
> custom behavior when links are encountered.  And it may also be useful
> to have a variant of AT_THIS_ROOT where trying to escape is an error
> instead of having it just get stuck at the root.

AT_USER_LINKS indicating that userspace wants to resolve symlinks
themselves?