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[2620:137:e000::1:20]) by mx.google.com with ESMTP id k6-20020a63d846000000b003fc51453576si10074675pgj.545.2022.07.11.04.42.38; Mon, 11 Jul 2022 04:42:50 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=iZzvVcte; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230389AbiGKLXy (ORCPT + 99 others); Mon, 11 Jul 2022 07:23:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230359AbiGKLXH (ORCPT ); Mon, 11 Jul 2022 07:23:07 -0400 Received: from mail-ed1-x52c.google.com (mail-ed1-x52c.google.com [IPv6:2a00:1450:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 914D237FA8; Mon, 11 Jul 2022 03:51:28 -0700 (PDT) Received: by mail-ed1-x52c.google.com with SMTP id w12so4988016edd.13; Mon, 11 Jul 2022 03:51:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=VK08yQTJ99mufpNp27xubsdOIIjMExE65sg5hpJC6W8=; b=iZzvVctewcKQocbxZXTD2xaYK71jGE8DBwGmiIb7/RjBQGsQAP2re8q9deGfdCBYPM q45s+T/m6yLcGhYjLphHnlB1HcFU0reX2CLEqA4HLzFlklecDyYu9OiCkuyCLTWj+ELS KkS73iukQ+5Bv8yXy3Uv2AkPoxkBKiKlgmFv8odpUX2hN0vIAj9IgGcN/fsPhVJtoOq6 zmn3kBYgbIFHg06ZWrQuOK1PhxmSDLzTpx21+9thhv0J0P457fwqlG8kiCGzgT5BEM9b 3lCtwNC3dL39cY9COM1weGQMOjVM0vNavUrUKe3MXRELxtirtC8QX+cbYc5RxXwCBguX j+Lw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=VK08yQTJ99mufpNp27xubsdOIIjMExE65sg5hpJC6W8=; b=QxoJJMhD1GwmkadlY49FXT1ROiNT+/hMTFDy6KHW0hRXq/tOxMKtGWeqYFqIrHj4B0 CDfkQuz+IuBw4VvziD+29qVfzS1Z9AJdJmqNVawm12mKbuWuO4NlF5QBeykkWtElVa3a nl87ZaYGWhhhraCQWHLkQRmLoeXywHocnB9uhaAJyU9cRsrHKA5dYQckLmKeXcneC5tC ivFdaL3RrIWVuxx/iRJRKT2uO4fzMV2lwG8ZiHCCnSTn1OodGjRz2p94D4RNcxdtfwIp AwypqrIYpNQQkhjeH5JiflKkgKsZVC4UXx7gWKzQnwdCHvbRvf9Cfu6pFIw4GYZwikRp kVrA== X-Gm-Message-State: AJIora9XRXcSM6QMcVfJQI33rhk0s19V6GVwM84+YYcs50Rz0E895CVB RCSCnbldGFMT2y5LK+5kikc= X-Received: by 2002:a05:6402:d0a:b0:437:66ca:c211 with SMTP id eb10-20020a0564020d0a00b0043766cac211mr24216273edb.29.1657536687051; Mon, 11 Jul 2022 03:51:27 -0700 (PDT) Received: from krava ([151.14.22.253]) by smtp.gmail.com with ESMTPSA id g12-20020aa7d1cc000000b00435726bd375sm4121080edp.57.2022.07.11.03.51.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Jul 2022 03:51:26 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Mon, 11 Jul 2022 12:51:22 +0200 To: Artem Savkov Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Andrea Arcangeli , dvacek@redhat.com Subject: Re: [RFC PATCH bpf-next 0/4] bpf_panic() helper Message-ID: References: <20220711083220.2175036-1-asavkov@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220711083220.2175036-1-asavkov@redhat.com> X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 11, 2022 at 10:32:16AM +0200, Artem Savkov wrote: > eBPF is often used for kernel debugging, and one of the widely used and > powerful debugging techniques is post-mortem debugging with a full memory dump. > Triggering a panic at exactly the right moment allows the user to get such a > dump and thus a better view at the system's state. This patchset adds > bpf_panic() helper to do exactly that. FWIW I was asked for such helper some time ago from Daniel Vacek, cc-ed jirka > > I realize that even though there are multiple guards present, a helper like > this is contrary to BPF being "safe", so this is sent as RFC to have a > discussion on whether adding destructive capabilities is deemed acceptable. > > Artem Savkov (4): > bpf: add a sysctl to enable destructive bpf helpers > bpf: add BPF_F_DESTRUCTIVE flag for BPF_PROG_LOAD > bpf: add bpf_panic() helper > selftests/bpf: bpf_panic selftest > > include/linux/bpf.h | 8 + > include/uapi/linux/bpf.h | 13 ++ > kernel/bpf/core.c | 1 + > kernel/bpf/helpers.c | 13 ++ > kernel/bpf/syscall.c | 33 +++- > kernel/bpf/verifier.c | 7 + > kernel/trace/bpf_trace.c | 2 + > tools/include/uapi/linux/bpf.h | 13 ++ > .../selftests/bpf/prog_tests/bpf_panic.c | 144 ++++++++++++++++++ > 9 files changed, 233 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_panic.c > > -- > 2.35.3 >