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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A1F2C433FE for ; Mon, 28 Nov 2022 20:25:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234026AbiK1UZX (ORCPT ); Mon, 28 Nov 2022 15:25:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234047AbiK1UZV (ORCPT ); Mon, 28 Nov 2022 15:25:21 -0500 Received: from mail-ej1-x62f.google.com (mail-ej1-x62f.google.com [IPv6:2a00:1450:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 585132A708 for ; Mon, 28 Nov 2022 12:25:20 -0800 (PST) Received: by mail-ej1-x62f.google.com with SMTP id n20so28875764ejh.0 for ; Mon, 28 Nov 2022 12:25:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=6JgCBbmVQED94QkggINgfKVFlLmfgr8GMlU1I22D1Ow=; b=gbwpGWuzO84IsqbkbtWFg8aZYwjiMvyMa9cmyvFd8f00dL5LtHTy9YwI2Qy0cpUFRP 4erJvuNfDdGISnsj+Oes4oE/iyvjGTpkFkVTR8Agm14l/DIwD+Wykh8ceBy63xOMNAUH fHap2r4AN7QpcpSv1CBL5AhdDWDOEfRBtTJ15ky3K8AGNw2ebOccJktkGCfXL/nu7CxJ O1fym8Y6jW++Aj/RLhTTgpGS5THodweEbDL9C/LkMtr2yQJxnOfHWzxi8RmrhLmepHJ3 5qjn4dBNHQPZi4yY6EU0/LXDQgJle+yWlhF4MzaDwY8GTPSkUdLCmXdRxDaP/TchNk4j drSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=6JgCBbmVQED94QkggINgfKVFlLmfgr8GMlU1I22D1Ow=; b=WtDq4VVZEWiybVPRh9+/2cMpXZCJSIe4LvdH9FL0w1l+gTFLdGCK1m///i/l0cZ8mk eROIoTJIjZ3qiSN/RKzTvcadCx/Z8ap1SGJJ+M3d6hX+O84LxqDhgigkiP910Zje5Mky 4XB7SbSWtSNRkU893LldDbPgMg3Yofk1zj2OgcAthSvWUYVkjknp1yOXNs04PA5pQHt5 gDFk+Xju5xLZucjaPzHABaVUN+WLTMtihSQD/7G3JUombtCgZ4GawO3vSHfCCCLuSd6G zBJ0Y7gkVppXLdb51aRxZ3jJSG+l1TcbH7SgwyW++L1Na2V9L5LhdgzrAoer4deSoA5/ rc+w== X-Gm-Message-State: ANoB5pltaZ0Dh8tsVjJgLiM/1q2yYQtQ87nj5OdtBLGSBfU/vsqIb5j6 KF4eaaYPiThOhmsvj6tYQIHNkLEAAhik+h7EIgA= X-Google-Smtp-Source: AA0mqf6zwmgz9OH19DpsVIlPuh7X80CYXXoct53QoB/5C8uRXHptnxJTSSUy0rWxXS2ryVW4sk/BvTzD7C/BdFd1tUo= X-Received: by 2002:a17:906:2ac3:b0:7ad:f2f9:2b49 with SMTP id m3-20020a1709062ac300b007adf2f92b49mr32525478eje.94.1669667118732; Mon, 28 Nov 2022 12:25:18 -0800 (PST) MIME-Version: 1.0 References: <20221128132915.141211-1-jolsa@kernel.org> <20221128132915.141211-2-jolsa@kernel.org> In-Reply-To: From: Alexei Starovoitov Date: Mon, 28 Nov 2022 12:25:07 -0800 Message-ID: Subject: Re: [PATCHv4 bpf-next 1/4] bpf: Mark vma objects as trusted for task_vma iter and find_vma callback To: Yonghong Song Cc: Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , bpf , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Nov 28, 2022 at 11:04 AM Yonghong Song wrote: > > > > On 11/28/22 10:43 AM, Alexei Starovoitov wrote: > > On Mon, Nov 28, 2022 at 5:29 AM Jiri Olsa wrote: > >> > >> Marking following vma objects as trusted so they can be used > >> as arguments for kfunc function added in following changes: > >> > >> - vma object argument in find_vma callback function > >> - vma object in context of task_vma iterator program > >> > >> Both places lock vma object so it can't go away while running > >> the bpf program. > >> > >> Signed-off-by: Jiri Olsa > >> --- > >> kernel/bpf/task_iter.c | 2 +- > >> kernel/bpf/verifier.c | 2 +- > >> 2 files changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c > >> index c2a2182ce570..cd67b3cadd91 100644 > >> --- a/kernel/bpf/task_iter.c > >> +++ b/kernel/bpf/task_iter.c > >> @@ -755,7 +755,7 @@ static struct bpf_iter_reg task_vma_reg_info = { > >> { offsetof(struct bpf_iter__task_vma, task), > >> PTR_TO_BTF_ID_OR_NULL }, > >> { offsetof(struct bpf_iter__task_vma, vma), > >> - PTR_TO_BTF_ID_OR_NULL }, > >> + PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED }, > > > > Yonghong, Song, > > > > Do you remember when task or vma is NULL here? > > Maybe we can do: if (!task || !vma) skip prog run > > in __task_vma_seq_show() > > and make both pointers as PTR_TO_BTF_ID | PTR_TRUSTED? > > The 'NULL' is to indicate the last bpf prog run before iteration > ends. It is to provide an opportunity for bpf program to know > all regular iterations are done and the bpf program can do > end aggregation or print a footer if the prog link is cat'able. Ahh. Right. Now I remember :) I think we're fine with PTR_TRUSTED here. The pointer still has to be checked for != NULL before being dereferenced or passed into kfunc.