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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 E62BAC04AAD for ; Mon, 6 May 2019 18:31:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC20F2082F for ; Mon, 6 May 2019 18:31:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="wHqNHSAs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726743AbfEFSb0 (ORCPT ); Mon, 6 May 2019 14:31:26 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:43021 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726487AbfEFSb0 (ORCPT ); Mon, 6 May 2019 14:31:26 -0400 Received: by mail-pf1-f193.google.com with SMTP id c6so2009431pfa.10 for ; Mon, 06 May 2019 11:31:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=u2WJ5ZOtTqRCq2Bj3IyfnxMM9vIhsCBOCI54Jc0LH2Q=; b=wHqNHSAsS23xI3ZnU/TXNpgHK+naa0sZTuUJTkw5wNoYxgD4TWaLI1PobG9xOoyzxQ MlZh0VSWy8sGnbihqFf6QyghvhKC4Eqwjii6zk3RM5qxGJe67sI14zqOgLtNgMNcmq8G ES2qaktt/Ae3srP88KrdZfDDVTvJNi1fLaaxo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=u2WJ5ZOtTqRCq2Bj3IyfnxMM9vIhsCBOCI54Jc0LH2Q=; b=dVdMpWaIyDaBicLoL80qHSZnBVACf4Pi8613QMZuG04AD2A1XYTkESARLjqjTQh0qn Ipxd+FY1+lLjyz/85NiUUYH/cmJ0xMgMQvYR6xWQMsewQkE6iL2+i6Jbc98mmspE8xbv MDddWF6TdabTKfFxd5uCTOmkE7eH/beOUx4WaaQhGcu5N/7l5hQVpjBvqodgoUF5r4PL Ec6PtSu8XCDbgpxD/dqlJTXBeJP8J3SY2P4qjTUR2jqQA4qS1a16TnXXNsdPoxbHlnV3 cV9FbMG03IEFvip09Yrpkw44eCZaQyqlBnTPpGrc6/Et5YmzK5Us8jAcYka9lTxSuMdz pPnw== X-Gm-Message-State: APjAAAViCJ7xTIL6KZvmbMNUKW0FoLVbZ50V7vTmN4qOETopg8od/bqW N/a3PEgZ/PL0NVb/Q6mpYVPUgQ== X-Google-Smtp-Source: APXvYqzCtja3Z7+DUcUlq2ExNEHUs7lMAhzHKGQIy9/x0+a2YCuTRp0jHZFxvINK29euToRW4QLdjA== X-Received: by 2002:a63:5c1b:: with SMTP id q27mr34566094pgb.127.1557167484501; Mon, 06 May 2019 11:31:24 -0700 (PDT) Received: from joelaf.cam.corp.google.com ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id h30sm21412414pgi.38.2019.05.06.11.31.20 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 06 May 2019 11:31:23 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Michal Gregorczyk , Adrian Ratiu , Mohammad Husain , Qais Yousef , Srinivas Ramana , duyuchao , Manjo Raja Rao , Karim Yaghmour , Tamir Carmeli , Yonghong Song , Alexei Starovoitov , Brendan Gregg , Masami Hiramatsu , Peter Ziljstra , Andrii Nakryiko , Steven Rostedt , Kees Cook , kernel-team@android.com, bpf@vger.kernel.org, Daniel Borkmann , Ingo Molnar , Martin KaFai Lau , netdev@vger.kernel.org, Song Liu Subject: [PATCH v2 1/4] bpf: Add support for reading user pointers Date: Mon, 6 May 2019 14:31:13 -0400 Message-Id: <20190506183116.33014-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The eBPF based opensnoop tool fails to read the file path string passed to the do_sys_open function. This is because it is a pointer to userspace address and causes an -EFAULT when read with probe_kernel_read. This is not an issue when running the tool on x86 but is an issue on arm64. This patch adds a new bpf function call based which calls the recently proposed probe_user_read function [1]. Using this function call from opensnoop fixes the issue on arm64. [1] https://lore.kernel.org/patchwork/patch/1051588/ Cc: Michal Gregorczyk Cc: Adrian Ratiu Cc: Mohammad Husain Cc: Qais Yousef Cc: Srinivas Ramana Cc: duyuchao Cc: Manjo Raja Rao Cc: Karim Yaghmour Cc: Tamir Carmeli Cc: Yonghong Song Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: Masami Hiramatsu Cc: Peter Ziljstra Cc: Andrii Nakryiko Cc: Steven Rostedt Cc: Kees Cook Cc: kernel-team@android.com Signed-off-by: Joel Fernandes (Google) --- Masami, could you carry these patches in the series where are you add probe_user_read function? Previous submissions is here: https://lore.kernel.org/patchwork/patch/1069552/ v1->v2: split tools uapi sync into separate commit, added deprecation warning for old bpf_probe_read function. include/uapi/linux/bpf.h | 9 ++++++++- kernel/trace/bpf_trace.c | 22 ++++++++++++++++++++++ 2 files changed, 30 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 929c8e537a14..8146784b9fe3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2431,6 +2431,12 @@ union bpf_attr { * Return * A **struct bpf_sock** pointer on success, or **NULL** in * case of failure. + * + * int bpf_probe_read_user(void *dst, int size, void *src) + * Description + * Read a userspace pointer safely. + * Return + * 0 on success or negative error */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -2531,7 +2537,8 @@ union bpf_attr { FN(sk_fullsock), \ FN(tcp_sock), \ FN(skb_ecn_set_ce), \ - FN(get_listener_sock), + FN(get_listener_sock), \ + FN(probe_read_user), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d64c00afceb5..7485deb0777f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -153,6 +153,26 @@ static const struct bpf_func_proto bpf_probe_read_proto = { .arg3_type = ARG_ANYTHING, }; +BPF_CALL_3(bpf_probe_read_user, void *, dst, u32, size, const void *, unsafe_ptr) +{ + int ret; + + ret = probe_user_read(dst, unsafe_ptr, size); + if (unlikely(ret < 0)) + memset(dst, 0, size); + + return ret; +} + +static const struct bpf_func_proto bpf_probe_read_user_proto = { + .func = bpf_probe_read_user, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_UNINIT_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_ANYTHING, +}; + BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, u32, size) { @@ -571,6 +591,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_map_delete_elem_proto; case BPF_FUNC_probe_read: return &bpf_probe_read_proto; + case BPF_FUNC_probe_read_user: + return &bpf_probe_read_user_proto; case BPF_FUNC_ktime_get_ns: return &bpf_ktime_get_ns_proto; case BPF_FUNC_tail_call: -- 2.21.0.1020.gf2820cf01a-goog