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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 BD4BCC433ED for ; Wed, 31 Mar 2021 14:05:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FD1660FDB for ; Wed, 31 Mar 2021 14:05:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235945AbhCaOEq (ORCPT ); Wed, 31 Mar 2021 10:04:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235951AbhCaOE0 (ORCPT ); Wed, 31 Mar 2021 10:04:26 -0400 Received: from mail-lj1-x22a.google.com (mail-lj1-x22a.google.com [IPv6:2a00:1450:4864:20::22a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E94F5C06174A for ; Wed, 31 Mar 2021 07:04:25 -0700 (PDT) Received: by mail-lj1-x22a.google.com with SMTP id 184so23967853ljf.9 for ; Wed, 31 Mar 2021 07:04:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7WkKKW/QkEs9/kkL1SzWso2zmgtPiw9JFTK148I7Nb4=; b=niP6gSWqtgY8fqKdzU9VHeMUI4+Y+aJZqdJSpI7MrXBBXbr/yaOMsYQfYPtRMHvRbr HFVoWRpG01gTfsI1lXIUDCA6ip2c2A8W/taxgcGCoJ7VmKM/TJYvM9p4JFAmOjKjWed/ qYpl40v1nu9CC9vOjChykYcdyjD5HQw6VVb3w= 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=7WkKKW/QkEs9/kkL1SzWso2zmgtPiw9JFTK148I7Nb4=; b=bd9/c0tJ83t1mM3FMigXSgzvVAYY2C76L8v2XZRkgtZA9kS6HlBd/rZRXgGIUY+62P RCWJB+NKVR6UOGpl4C564vjF8x4ANtZyhVbYTuGwGNsbNgT8UAKYYllf9llMB8KJK+Kt cuZZhtR4yzRCUO70ydJ1AKycsTesN3r1y/yaeMAhoqrJMGBTrl/Hklxev7QYl2yY5upi ZjoGMEvqBbI9JznlniJqtEvqULV2fPGY+VjbSTGHA0Af/ZWiCEbggloeADYLxzSmGn8l PE3e8akcoVwtMjoZToEB++y823w5hyIrHNpVGv2BbY+dL5kC2mY8h/pPhENOrMls06/a gyMA== X-Gm-Message-State: AOAM531VBgtgqaAF9R4o8DyraMu25lM19PGKRuu0qOBq64hux4v+mLEu e7m1MrQ3Patd3fEL6zzukXGBvsBKToWSZPVgkLba6Lv6J2o= X-Google-Smtp-Source: ABdhPJwGGJC46aQqg9+k+oN5WbxooZfC2RyoJrBbGmk9xp43AiM5ChwTRs/po0Pv34t6pPvRXgiXVBdqaoqxaQxZxkQ= X-Received: by 2002:a05:651c:118b:: with SMTP id w11mr2156382ljo.223.1617199463908; Wed, 31 Mar 2021 07:04:23 -0700 (PDT) MIME-Version: 1.0 References: <20210326160501.46234-1-lmb@cloudflare.com> In-Reply-To: <20210326160501.46234-1-lmb@cloudflare.com> From: Lorenz Bauer Date: Wed, 31 Mar 2021 15:04:13 +0100 Message-ID: Subject: Re: [PATCH bpf v2 1/2] bpf: link: refuse non-O_RDWR flags in BPF_OBJ_GET To: Alexei Starovoitov , Daniel Borkmann Cc: kernel-team , Networking , bpf Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org 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. Best -- Lorenz Bauer | Systems Engineer 6th Floor, County Hall/The Riverside Building, SE1 7PB, UK www.cloudflare.com