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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21732C433F5 for ; Mon, 25 Oct 2021 21:24:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0517760FDC for ; Mon, 25 Oct 2021 21:24:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232524AbhJYV07 (ORCPT ); Mon, 25 Oct 2021 17:26:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51262 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231246AbhJYV06 (ORCPT ); Mon, 25 Oct 2021 17:26:58 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D874C061243 for ; Mon, 25 Oct 2021 14:24:35 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id np13so9265235pjb.4 for ; Mon, 25 Oct 2021 14:24:35 -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=cVVSf4gV+VHKaMcPkqXKR+j1Pi643cPAlkbYEqi72eA=; b=KaZ4GqG+L5BbOZwNRz+ZFzGoL6DWdRGwHmkuHMpBhtnIoIFP7poSXqXdiC9eBIyduE 6sSiiJ6O5yk+WTD2QWicyc0FTSHsKOmopPGxh0MCwFc1j6PJnh91QVp8PhupQgoFO3oT Q3TjaKiDTb/FYgwk7I8NiHqVtaa3U7K42dudE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=cVVSf4gV+VHKaMcPkqXKR+j1Pi643cPAlkbYEqi72eA=; b=carsTivibwt6KAXy6Sjsw6N8E7xtXhyOlguWb8d1bUgLpfmDYLMOOYoSJEQE2Kj+N8 4FzGRvKb+8b/EC42sIUMcpGZea4VGjWPEs60ASEoCpUTEZKC4NC11/Xfb/NsOKZSGf69 DHqOAzFlCY10K4TtgV22tjJ8TG1Zuu5aYQEGXak5HIugeGsVD1/zR6pWdi/JWJK5Uw16 IBNJfjxkXTbvQd2hnvBND3SFr731D/7Mmgzr+HB1iv9rK5QLz9l5hFAUX88ZYJUgNfcV S4r1XuAwtoHsI/MoY/pIsSTS97p9kD/k4BU5ZSLO4kj/CdR0+NhKjS7XizedCGWrNWa3 ZyGQ== X-Gm-Message-State: AOAM530YjwKWadThRcnzwGtbc80YTC1fgLNm95/gTDe8pzA8sZe1QvFw fceGs8pj9ipdxZq24QNtXOS6Pw== X-Google-Smtp-Source: ABdhPJxJj5ssF3jbgx6poVT90eIK8mxh0IHB+tSEXpyDuQrCC/LZvCXj6OL26lmlGf8XqbtQ3X6+/A== X-Received: by 2002:a17:90a:514f:: with SMTP id k15mr15033244pjm.71.1635197075028; Mon, 25 Oct 2021 14:24:35 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id t11sm21841162pfj.173.2021.10.25.14.24.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Oct 2021 14:24:34 -0700 (PDT) Date: Mon, 25 Oct 2021 14:24:34 -0700 From: Kees Cook To: Yafang Shao Cc: akpm@linux-foundation.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, arnaldo.melo@gmail.com, pmladek@suse.com, peterz@infradead.org, viro@zeniv.linux.org.uk, valentin.schneider@arm.com, qiang.zhang@windriver.com, robdclark@chromium.org, christian@brauner.io, dietmar.eggemann@arm.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, davem@davemloft.net, kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, dennis.dalessandro@cornelisnetworks.com, mike.marciniszyn@cornelisnetworks.com, dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, oliver.sang@intel.com, lkp@intel.com, Andrii Nakryiko Subject: Re: [PATCH v6 08/12] tools/bpf/bpftool/skeleton: make it adopt to task comm size change Message-ID: <202110251421.7056ACF84@keescook> References: <20211025083315.4752-1-laoar.shao@gmail.com> <20211025083315.4752-9-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211025083315.4752-9-laoar.shao@gmail.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Oct 25, 2021 at 08:33:11AM +0000, Yafang Shao wrote: > bpf_probe_read_kernel_str() will add a nul terminator to the dst, then > we don't care about if the dst size is big enough. > > Signed-off-by: Yafang Shao > Cc: Mathieu Desnoyers > Cc: Arnaldo Carvalho de Melo > Cc: Andrii Nakryiko > Cc: Peter Zijlstra > Cc: Steven Rostedt > Cc: Al Viro > Cc: Kees Cook > Cc: Petr Mladek So, if we're ever going to copying these buffers out of the kernel (I don't know what the object lifetime here in bpf is for "e", etc), we should be zero-padding (as get_task_comm() does). Should this, instead, be using a bounce buffer? get_task_comm(comm, task->group_leader); bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm), comm); -Kees > --- > tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c > index d9b420972934..f70702fcb224 100644 > --- a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c > +++ b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c > @@ -71,8 +71,8 @@ int iter(struct bpf_iter__task_file *ctx) > > e.pid = task->tgid; > e.id = get_obj_id(file->private_data, obj_type); > - bpf_probe_read_kernel(&e.comm, sizeof(e.comm), > - task->group_leader->comm); > + bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm), > + task->group_leader->comm); > bpf_seq_write(ctx->meta->seq, &e, sizeof(e)); > > return 0; > -- > 2.17.1 > -- Kees Cook