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Date: Sun, 6 Jan 2013 16:31:00 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Meredydd Luff <meredydd@senatehouse.org>
Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Kees Cook <keescook@chromium.org>, Ingo Molnar <mingo@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH signal#execve2] syscalls,x86: Add execveat() system call
 (v3)
Message-ID: <20130106163100.GI4939@ZenIV.linux.org.uk>
References: <1347411352-12392-1-git-send-email-meredydd@senatehouse.org>
 <20120912011654.GQ13973@ZenIV.linux.org.uk>
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OK, now that sys_execve() unification has settled down, let's get back
to this one.  The real problem is what you are doing with bprm->filename
and bprm->interp; blind use of ->d_name is completely wrong.

For what it's worth, how should it work for e.g. shell scripts?  That's
the main user of bprm->{filename,interp}, after all - other places are
either seriously exotic or are just using it for printks.

For shell scripts, however, these guys are really used - we have the original
argv[0] removed and <shell name> <optional argument> <filename> pushed in
its place.

How will it work with execveat()?  If we have procfs in place, we can
cook an equivalent pathname (/proc/self/fd/<n>/<relative part of pathname>),
but then why not do just that in userland and be done with that?