Date: Mon, 7 Dec 2015 21:38:24 +0100
From: Jann Horn <jann@thejh.net>
To: Kees Cook <keescook@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Oleg Nesterov <oleg@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        James Morris <james.l.morris@oracle.com>,
        "Serge E. Hallyn" <serge.hallyn@ubuntu.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Joe Perches <joe@perches.com>, Thomas Gleixner <tglx@linutronix.de>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        "security@kernel.org" <security@kernel.org>, Willy Tarreau <w@1wt.eu>
Subject: Re: [PATCH] ptrace: use fsuid, fsgid, effective creds for fs access
 checks
Message-ID: <20151207203824.GA27364@pc.thejh.net>
References: <20151109131902.db961a5fe7b7fcbeb14f72fc@linux-foundation.org>
 <1449367476-15673-1-git-send-email-jann@thejh.net>
 <CAGXu5jJKOnWWSuLO5zWZ9=7Nhv0hWvJ0wEVJ3n+URY7-q_BCJw@mail.gmail.com>
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On Mon, Dec 07, 2015 at 12:32:06PM -0800, Kees Cook wrote:
> On Sat, Dec 5, 2015 at 6:04 PM, Jann Horn <jann@thejh.net> wrote:
[...]
> > -       if (ptrace_may_access(task, PTRACE_MODE_READ)) {
> > +       if (ptrace_may_access(task, PTRACE_MODE_READ | PTRACE_MODE_FSCR=
EDS)) {
>=20
> This should maybe use the PTRACE_MODE_READ_FSCREDS macro?

Oh, yes. I don't know how I missed that. :/


> >                 error =3D ns_get_path(&ns_path, task, ns_ops);
> >                 if (!error)
> >                         nd_jump_link(&ns_path);
> > @@ -63,7 +63,7 @@ static int proc_ns_readlink(struct dentry *dentry, ch=
ar __user *buffer, int bufl
> >         if (!task)
> >                 return res;
> >
> > -       if (ptrace_may_access(task, PTRACE_MODE_READ)) {
> > +       if (ptrace_may_access(task, PTRACE_MODE_READ | PTRACE_MODE_FSCR=
EDS)) {
>=20
> same here?

Yes.
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