linux-kernel - [REVIEW][PATCH 0/3] Fixing ptrace vs exec vs userns interactions

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Date:   Thu, 17 Nov 2016 11:02:47 -0600
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Linux Containers <containers@...ts.linux-foundation.org>
Cc:     Oleg Nesterov <oleg@...hat.com>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm\@kvack.org" <linux-mm@...ck.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        Michal Hocko <mhocko@...nel.org>, Jann Horn <jann@...jh.net>,
        Willy Tarreau <w@....eu>, Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...capital.net>
Subject: [REVIEW][PATCH 0/3] Fixing ptrace vs exec vs userns interactions

With everyone heading to Kernel Summit and Plumbers I put this set of
patches down temporarily.   Now is the time to take it back up and to
make certain I am not missing something stupid in this set of patches.

There are other issues in this area as well, but these are the pieces
that I can see clearly, and have tested fixes for.

Andy as to your criticism about using strace sudo I can't possibly see
how that is effective or useful.  Under strace sudo won't run as root
today, and will immediately exit because it is not root.  Furthermore
the only place I can find non-readable executables is people hardening
suid root executables so they are more difficult to trace.  So I
definitely think we should honor the unix permissions and people's
expressed wishes.

Eric W. Biederman (3):
      ptrace: Capture the ptracer's creds not PT_PTRACE_CAP
      exec: Don't allow ptracing an exec of an unreadable file
      exec: Ensure mm->user_ns contains the execed files

 fs/exec.c                  | 26 +++++++++++++++++++++++---
 include/linux/capability.h |  2 ++
 include/linux/ptrace.h     |  1 -
 include/linux/sched.h      |  1 +
 kernel/capability.c        | 36 ++++++++++++++++++++++++++++++++++--
 kernel/ptrace.c            | 12 +++++++-----
 6 files changed, 67 insertions(+), 11 deletions(-)