[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150604183149.GA560@redhat.com>
Date: Thu, 4 Jun 2015 20:31:49 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Tycho Andersen <tycho.andersen@...onical.com>
Cc: linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...capital.net>,
Will Drewry <wad@...omium.org>,
Roland McGrath <roland@...k.frob.com>,
Pavel Emelyanov <xemul@...allels.com>,
"Serge E. Hallyn" <serge.hallyn@...ntu.com>
Subject: Re: [PATCH v2] seccomp: add ptrace options for suspend/resume
On 06/03, Tycho Andersen wrote:
>
> @@ -556,6 +557,11 @@ static int ptrace_setoptions(struct task_struct *child, unsigned long data)
> if (data & ~(unsigned long)PTRACE_O_MASK)
> return -EINVAL;
>
> +#ifdef CONFIG_CHECKPOINT_RESTORE
> + if (data & PTRACE_O_SUSPEND_SECCOMP && !may_suspend_seccomp())
> + return -EPERM;
> +#endif
> +
Well. This -EPERM doesn't look consistent...
if config_enabled(CONFIG_CHECKPOINT_RESTORE) == F, we return success
but PTRACE_O_SUSPEND_SECCOMP has no effect because of another ifdef in
seccomp.
OTOH, if CONFIG_SECCOMP=n, this option has no effect too but we return
-EPERM even.
Also. Suppose that the tracer sets SUSPEND_SECCOMP and then drops
CAP_SYS_ADMIN. After that it can't set or clear other ptrace options.
So if we really want the security checks (I still think we do not ;)
then we should probably check "flags & SUSPEND_SECCOMP" as well.
> +#ifdef CONFIG_CHECKPOINT_RESTORE
> +bool may_suspend_seccomp(void)
> +{
> + if (!capable(CAP_SYS_ADMIN))
> + return false;
> +
> + if (current->seccomp.mode != SECCOMP_MODE_DISABLED)
> + return false;
Heh. OK, I won't argue with the new check too ;)
Oleg.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists