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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 CB2F8C433ED for ; Thu, 1 Apr 2021 19:16:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F6DE6101E for ; Thu, 1 Apr 2021 19:16:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234256AbhDATQB (ORCPT ); Thu, 1 Apr 2021 15:16:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234685AbhDATOU (ORCPT ); Thu, 1 Apr 2021 15:14:20 -0400 Received: from mail-lj1-x22b.google.com (mail-lj1-x22b.google.com [IPv6:2a00:1450:4864:20::22b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65BD3C0613A9; Thu, 1 Apr 2021 11:04:44 -0700 (PDT) Received: by mail-lj1-x22b.google.com with SMTP id s17so3193378ljc.5; Thu, 01 Apr 2021 11:04:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9JnNqbp+jfX8Yeet9lEdVPDzns8/gphEhHuNm2ARo20=; b=YyCsKv7oInpoc6D4tMYefd1GPWGDDkJQMFslwOa53O8n2rmnnZ/g7VBGMTvUOl0fGJ D7wLA/2MMrzQZQsV5nnS6vjfRwTFespIpiD5VOxMgfRiMYGwZDMmgzE7CQuye+tzzn60 wYUMO/dU6Y6ioGLouBz7BVR60ogvHnxVFSDp3jz9uWyECgmlEDCbWEB5KTYSsJHlCzFq nAyxXXnuCqdggk8KI2kowZYTH2lLDH8mcoL2P8WfDOYIVfG3TZ2KF1mxZm9XLQGiO4yj zjb/C16bT3oab//EeilxrbhsPAmwSQBXao/HIEzYIc04WiBxs60pk966zzvL1MtDGfcg FQYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9JnNqbp+jfX8Yeet9lEdVPDzns8/gphEhHuNm2ARo20=; b=m4lfOU6M0C/Qo7uwQXWVUmWEOE66wDR7YNeGyU2itxvk8z2HhU9Q7EpEPc0ACcI/75 XPqCVbrADWi5sMERFWefokZzyE9DP658RVqnD3mvtIQn+2pKVJ6Abnw/ri8COs7nsFuW bwyrCEGYYDkazEmd3SsGHxgQA8+2hJhqcghn/4amdPCIRMpblMUN3wQc/qU/wy8H1IaD crFaw1dDLsQtRzOIeDkPFJGulkLQObGvQydLnHPPTknuzQwdrOpN8SENMt9mnGjc6baj o5TJ94QxzsbzKECTkGMalYN5CXGnBlvE9SPINYSlfhdvmfosan/lVszZezTVnacJfHq5 lAZg== X-Gm-Message-State: AOAM53062fjspvG1J9vq7tLuYWGaPVz9BrLjSmUgCMMRyLm5HSJzi+8j fmAM/YR8lP1KFWi7f/+6r16FSnvJEVMkH3YdS1pjhWXO X-Google-Smtp-Source: ABdhPJxnmVOSZRz8DqH/OxOr0exfcQnDyl/DbLWDDu5J0SJXup6oN/24+PhWtqGdP9OtPpXTRFzcfQpvbuRnNkdR75M= X-Received: by 2002:a2e:3608:: with SMTP id d8mr6155259lja.21.1617300282954; Thu, 01 Apr 2021 11:04:42 -0700 (PDT) MIME-Version: 1.0 References: <20210326160501.46234-1-lmb@cloudflare.com> In-Reply-To: From: Alexei Starovoitov Date: Thu, 1 Apr 2021 11:04:31 -0700 Message-ID: Subject: Re: [PATCH bpf v2 1/2] bpf: link: refuse non-O_RDWR flags in BPF_OBJ_GET To: Lorenz Bauer Cc: Alexei Starovoitov , Daniel Borkmann , kernel-team , Networking , bpf Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Mar 31, 2021 at 7:04 AM Lorenz Bauer wrote: > > On Fri, 26 Mar 2021 at 16:05, Lorenz Bauer wrote: > > > > Invoking BPF_OBJ_GET on a pinned bpf_link checks the path access > > permissions based on file_flags, but the returned fd ignores flags. > > This means that any user can acquire a "read-write" fd for a pinned > > link with mode 0664 by invoking BPF_OBJ_GET with BPF_F_RDONLY in > > file_flags. The fd can be used to invoke BPF_LINK_DETACH, etc. > > > > Fix this by refusing non-O_RDWR flags in BPF_OBJ_GET. This works > > because OBJ_GET by default returns a read write mapping and libbpf > > doesn't expose a way to override this behaviour for programs > > and links. > > Hi Alexei and Daniel, > > I think these two patches might have fallen through the cracks, could > you take a look? I'm not sure what the etiquette is around bumping a > set, so please let me know if you'd prefer me to send the patches with > acks included or something like that. It is still in patchworks. I didn't have time to think it through. Sorry for delay.