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,USER_AGENT_GIT autolearn=ham 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 C5AEEC04A6B for ; Mon, 6 May 2019 18:31:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D93020B7C for ; Mon, 6 May 2019 18:31:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="xbBnkKUC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726928AbfEFSbc (ORCPT ); Mon, 6 May 2019 14:31:32 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:46176 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726844AbfEFSb3 (ORCPT ); Mon, 6 May 2019 14:31:29 -0400 Received: by mail-pg1-f196.google.com with SMTP id t187so2749006pgb.13 for ; Mon, 06 May 2019 11:31:28 -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:in-reply-to:references :mime-version:content-transfer-encoding; bh=xhmLyaLAyu6ZncCjM6Pqxqgn8DvO3yzF5Ng7O6wfqzc=; b=xbBnkKUCkXZY8xbWHpA3tGU2J7SUUx7/NLgLAt3tyGUz03dKifE0RSHJtvpC+RPCPv IBlhboZr1JR6xw9oxPJLxTvvJ748640oM2RDzJFONho4jUOlkEZD8ihYogfdw8deWRWT /FwK3KlFafEFliWQl5Icqlt4W/GFxdGVylpIs= 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=xhmLyaLAyu6ZncCjM6Pqxqgn8DvO3yzF5Ng7O6wfqzc=; b=uagGV3kyLZZqL8JpoJ40G/0HBmvZd9m++LW+9n+qxvQdwK+aVTClqYDUrjhFKZLS1e DfPrNml0LAM2Yi+dscoo/coAtJuUhXdRNQ8KaBqaxz79qqqmepUmHPnvox2Tng3S3d0Y aLs2WdzsrYSfA2kikC/0ILD/Pmqssg2+szIQcNQ3ZFq3RxDqU730qY3AymaeRxcZZzoh 3G+wTEBglU2VN403kNWE+1ENBFXkvpg9ARebig9PF7RSaUY/lA4qnph5pzFGPYm8LsMm mG5BGAP8i1TFZPHaV1JhB5gIci+0ywZEnVPAavbHaTQapzTbHxX7u3PEXXSFeZd/eVTE H0Rg== X-Gm-Message-State: APjAAAUvtTVKegr6p1MxLotr/MLy8mhEkv7eBI+iYFl31dIMc/ejVGg/ P8UTNHHrRzL9GKsGqNwGxPnBCB8dEpQ= X-Google-Smtp-Source: APXvYqwcC5Kplq4r8tbbGJ9eiRVDoJAXyJYR3TAcvVzM6mKAQaUCaRbQ9kZ6/gmln3JqJYWTMS9nww== X-Received: by 2002:a63:d345:: with SMTP id u5mr32124227pgi.83.1557167487924; Mon, 06 May 2019 11:31:27 -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.38.2019.05.06.11.31.24 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 06 May 2019 11:31:27 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Adrian Ratiu , Alexei Starovoitov , Andrii Nakryiko , bpf@vger.kernel.org, Brendan Gregg , Daniel Borkmann , duyuchao , Ingo Molnar , Karim Yaghmour , Kees Cook , kernel-team@android.com, Manjo Raja Rao , Martin KaFai Lau , Masami Hiramatsu , Michal Gregorczyk , Mohammad Husain , netdev@vger.kernel.org, Peter Ziljstra , Qais Yousef , Song Liu , Srinivas Ramana , Steven Rostedt , Tamir Carmeli , Yonghong Song Subject: [PATCH v2 2/4] bpf: Add support for reading kernel pointers Date: Mon, 6 May 2019 14:31:14 -0400 Message-Id: <20190506183116.33014-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog In-Reply-To: <20190506183116.33014-1-joel@joelfernandes.org> References: <20190506183116.33014-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The bpf_probe_read function is ambiguous in whether the pointer being read is a kernel or user one. Add a specific function for kernel pointer in this patch. Previous patches add it for userspace pointers. Signed-off-by: Joel Fernandes (Google) --- 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 8146784b9fe3..05af4e1151d3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2437,6 +2437,12 @@ union bpf_attr { * Read a userspace pointer safely. * Return * 0 on success or negative error + * + * int bpf_probe_read_kernel(void *dst, int size, void *src) + * Description + * Read a kernel pointer safely. + * Return + * 0 on success or negative error */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -2538,7 +2544,8 @@ union bpf_attr { FN(tcp_sock), \ FN(skb_ecn_set_ce), \ FN(get_listener_sock), \ - FN(probe_read_user), + FN(probe_read_user), \ + FN(probe_read_kernel), /* 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 7485deb0777f..99dc354fd62b 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_kernel, void *, dst, u32, size, const void *, unsafe_ptr) +{ + int ret; + + ret = probe_kernel_read(dst, unsafe_ptr, size); + if (unlikely(ret < 0)) + memset(dst, 0, size); + + return ret; +} + +static const struct bpf_func_proto bpf_probe_read_kernel_proto = { + .func = bpf_probe_read_kernel, + .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_read_user, void *, dst, u32, size, const void *, unsafe_ptr) { int ret; @@ -593,6 +613,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_probe_read_proto; case BPF_FUNC_probe_read_user: return &bpf_probe_read_user_proto; + case BPF_FUNC_probe_read_kernel: + return &bpf_probe_read_kernel_proto; case BPF_FUNC_ktime_get_ns: return &bpf_ktime_get_ns_proto; case BPF_FUNC_tail_call: -- 2.21.0.1020.gf2820cf01a-goog