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 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 A7D4DC43460 for ; Sat, 17 Apr 2021 05:01:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 60BB66108B for ; Sat, 17 Apr 2021 05:01:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229572AbhDQFCX (ORCPT ); Sat, 17 Apr 2021 01:02:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37480 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229547AbhDQFCW (ORCPT ); Sat, 17 Apr 2021 01:02:22 -0400 Received: from mail-lf1-x129.google.com (mail-lf1-x129.google.com [IPv6:2a00:1450:4864:20::129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C647BC061574; Fri, 16 Apr 2021 22:01:56 -0700 (PDT) Received: by mail-lf1-x129.google.com with SMTP id j18so48013293lfg.5; Fri, 16 Apr 2021 22:01:56 -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=JS5ToxDYDEg+E8RwSyqs2bCJvCy+zGOhHKQvlmMv9O8=; b=nHUsfVFx1zCWs+niphx3RfnQ8oE4aMInQpEJwPGKuhvlgRv/xajSccq7IrCWza/nEU s1uF9Xy5U6HERGzLc61hTHdROlDAwNhCLVxPAZ0ihm/93AlZYquhLacDtPFacwLOy4fD I/m5AJ/BxUoQUW7s2TaLhAfNQzsvmGM/fiKeyuCskPPDmUnHz6bSGkJnA5ay6N+s4yrZ SsTUZSdsmFpVyZf9J8AUoQdqkUV9xSkDoD1Yw3wIVTy3hTJfWb/d4nXm/GENh8WYYd6V XQWFI4JDCAw409lUzsZJQmMxWwPh7Pa2Fld1Jhv41VRgZcKr0MMNt6PPHHp7Ar9Lrc0K mL4w== 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=JS5ToxDYDEg+E8RwSyqs2bCJvCy+zGOhHKQvlmMv9O8=; b=jVklfZYO58Zn20xrDzzih373Y0usPDq7gAk6HCeUgfwDJsxYT/iN8lWFnZepxykpqK DZe4JEZ5AzeY9GmVcRsNkt05cHVRwHyYUDinmxnGVxBJetuOtBhhw+Qf0K/OzmetZzac 0P9c5LW+e86sqMx5ZXzj4k8SLokcnXrROVqG6gxnlod0mUqoZ9+YfK89lAflKjYnMIXm MbpwqWw7T1+dfH8gi/YJlz8lMn6BmEdduuGV2wEEdUnqZx7nkmL3Qxyzykb0NNGbvLEh 0sGmAugzJIXlGL42jiEBRMeMs7d1Uv+8D5quScjP6zJ8CUFaZwhn+lUbugNW+9wSNP2S wqIA== X-Gm-Message-State: AOAM531afXERcTVYS5D2QQj8u1g9qa145BXpwkizTgOTra0VVuJ0Pl47 RY9VEHYM5pqMLfqX4n0V+VYkVLlTgzT46Jh+NGi69VIC X-Google-Smtp-Source: ABdhPJxcMTZXG0F1BOJAHysoyWx3MRoSkHObFdVFWelI6IRMHRjvQsLWAbn7sajMpHOqVLF1UjK7+r6giKvSvWUtHlA= X-Received: by 2002:a05:6512:2026:: with SMTP id s6mr5368136lfs.214.1618635715172; Fri, 16 Apr 2021 22:01:55 -0700 (PDT) MIME-Version: 1.0 References: <20210417033224.8063-1-alexei.starovoitov@gmail.com> <20210417033224.8063-12-alexei.starovoitov@gmail.com> In-Reply-To: From: Alexei Starovoitov Date: Fri, 16 Apr 2021 22:01:43 -0700 Message-ID: Subject: Re: [PATCH bpf-next 11/15] bpf: Add bpf_sys_close() helper. To: Al Viro Cc: "David S. Miller" , Daniel Borkmann , Andrii Nakryiko , Network Development , bpf , Kernel Team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Apr 16, 2021 at 9:04 PM Al Viro wrote: > > On Fri, Apr 16, 2021 at 08:46:05PM -0700, Alexei Starovoitov wrote: > > On Fri, Apr 16, 2021 at 8:42 PM Al Viro wrote: > > > > > > On Fri, Apr 16, 2021 at 08:32:20PM -0700, Alexei Starovoitov wrote: > > > > From: Alexei Starovoitov > > > > > > > > Add bpf_sys_close() helper to be used by the syscall/loader program to close > > > > intermediate FDs and other cleanup. > > > > > > Conditional NAK. In a lot of contexts close_fd() is very much unsafe. > > > In particular, anything that might call it between fdget() and fdput() > > > is Right Fucking Out(tm). > > > In which contexts can that thing be executed? > > > > user context only. > > It's not for all of bpf _obviously_. > > Let me restate the question: what call chains could lead to bpf_sys_close()? Already answered. User context only. It's all safe.