From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39425C0044D for ; Mon, 16 Mar 2020 21:24:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C0CC20674 for ; Mon, 16 Mar 2020 21:24:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Z4fiWqfQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732667AbgCPVYC (ORCPT ); Mon, 16 Mar 2020 17:24:02 -0400 Received: from mail-pj1-f65.google.com ([209.85.216.65]:55363 "EHLO mail-pj1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732567AbgCPVYC (ORCPT ); Mon, 16 Mar 2020 17:24:02 -0400 Received: by mail-pj1-f65.google.com with SMTP id mj6so8844174pjb.5 for ; Mon, 16 Mar 2020 14:24:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=k6XAwrWDY/zsycDAo2K53Vl70GhIjA99tBrFA4ZGhTE=; b=Z4fiWqfQ8XqKDmI6T07Gvt9pSMGVDJUgyS7JXSsUrxYXw5wRk0V8uSAvIqRruGXw0p HJuR1b+QA5U1tbigOvOVLQ4OgbkYu4GefP+XZUhBtOVBKbOY/TueH94wGRDdLo1r9nve DPmbJMLt1BiluEmWC3f8a1Tkp1qIPaTIIKm9w= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=k6XAwrWDY/zsycDAo2K53Vl70GhIjA99tBrFA4ZGhTE=; b=AtOS7u3FegFy46+4am/zRAl6rBkSZ6cCp4wx9EsPXppUvWdV5F8ZHygOJWgmfyyPp1 1Xf9y53aYW9iuqywb00i9RoGG+fqj9e4H7b66LTxPw1fY91rx8jbrxLHWkd+W/VQV5AJ +PZvP70/5Zf8aAVPopd38Dh6rojFmYaCNODueMYqr+pWUtuUJnBRFZaxeP+pNp8koh4o huy9IU0W7g8rJzPJNgod8vQ/7NuKyNRuSsA/h59LV9d7YkoczEf5X8pI+43fsC6Tk3bK tOifJjoxHVyiKob7OEfv6PPujP4+rxDdrw7Pja5iSz6glRCrY4ve36wNe9baXIcr3TOe d6JA== X-Gm-Message-State: ANhLgQ1WC1vYfk3JjDF2Y7w+6raa/hOXZOLoB7tOmP1VGX+bJmImMn5F JwqwscU10Ha9GHlF9UGXOym3Ng== X-Google-Smtp-Source: ADFU+vs68X9RkPUqkATV2iQxMOvZU1EVi/eKUQuxzDFOyagTnzRG37PM75ufsijB+ukeVItkeM7R/g== X-Received: by 2002:a17:90a:c08f:: with SMTP id o15mr1552021pjs.155.1584393841314; Mon, 16 Mar 2020 14:24:01 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id u26sm749763pfh.193.2020.03.16.14.24.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Mar 2020 14:24:00 -0700 (PDT) Date: Mon, 16 Mar 2020 14:23:59 -0700 From: Kees Cook To: Anton Protopopov Cc: Andy Lutomirski , Will Drewry , linux-kernel@vger.kernel.org, Daniel Borkmann , bpf@vger.kernel.org Subject: Re: [PATCH] seccomp: allow BPF_MOD ALU instructions Message-ID: <202003161423.B51FDA8083@keescook> References: <20200316163646.2465-1-a.s.protopopov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200316163646.2465-1-a.s.protopopov@gmail.com> Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Mar 16, 2020 at 04:36:46PM +0000, Anton Protopopov wrote: > The BPF_MOD ALU instructions could be utilized by seccomp classic BPF filters, > but were missing from the explicit list of allowed calls since its introduction > in the original e2cfabdfd075 ("seccomp: add system call filtering using BPF") > commit. Add support for these instructions by adding them to the allowed list > in the seccomp_check_filter function. > > Signed-off-by: Anton Protopopov This has been suggested in the past, but was deemed ultimately redundant: https://lore.kernel.org/lkml/201908121035.06695C79F@keescook/ Is there a strong reason it's needed? Thanks! -Kees > --- > kernel/seccomp.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > index b6ea3dcb57bf..cae7561b44d4 100644 > --- a/kernel/seccomp.c > +++ b/kernel/seccomp.c > @@ -206,6 +206,8 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) > case BPF_ALU | BPF_MUL | BPF_X: > case BPF_ALU | BPF_DIV | BPF_K: > case BPF_ALU | BPF_DIV | BPF_X: > + case BPF_ALU | BPF_MOD | BPF_K: > + case BPF_ALU | BPF_MOD | BPF_X: > case BPF_ALU | BPF_AND | BPF_K: > case BPF_ALU | BPF_AND | BPF_X: > case BPF_ALU | BPF_OR | BPF_K: > -- > 2.19.1 -- Kees Cook