From patchwork Thu Aug 8 00:07:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11082949 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1C1B513B1 for ; Thu, 8 Aug 2019 00:09:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 06A5328AB7 for ; Thu, 8 Aug 2019 00:09:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EC01128AC8; Thu, 8 Aug 2019 00:09:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5ECEC28AB7 for ; Thu, 8 Aug 2019 00:09:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389744AbfHHAI2 (ORCPT ); Wed, 7 Aug 2019 20:08:28 -0400 Received: from mail-qk1-f201.google.com ([209.85.222.201]:54876 "EHLO mail-qk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389732AbfHHAIZ (ORCPT ); Wed, 7 Aug 2019 20:08:25 -0400 Received: by mail-qk1-f201.google.com with SMTP id x28so4193013qki.21 for ; Wed, 07 Aug 2019 17:08:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=8yt0J0pt8aHuQPT7nXOB+XR/9vHKjGA14LTvJs583ko=; b=R/kcNwmgbX+sKxSEQsYUzy5uU1k4FuUGmKARS2fBkMDe+ZiZsiyQt4yd4lR2R6nsjb wpjUNdDlXARvS5FUlu+PthqfTsorWtf88u58FgL5DuOglBXkEUFf7g8Wu357CPD1PEj5 58PkL4hmWYOY6O8/DHp19TdCXlQTC0/7jAjVyZ3EbA8nlErkBnnDpNrUXmd6bZLaLCSp 7+JRhvoUP7mO5NTA3UhzFDk0WXgQYiBqgdLwiUahFgrbJ15hUKqPL5FbLDdHBnCsuzTv 1cFf2P13Z4ho/mB37/OdEUSP3mKSUvgH6BHIR9A0yKppvEfzMfT+TzvFoDGYMESasC8r 2Mvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=8yt0J0pt8aHuQPT7nXOB+XR/9vHKjGA14LTvJs583ko=; b=L2E65iMV9ceNvBflKXW/qIaagxa1VH7ZCf9+rpFHS9UIbgva/q2dBcialHdqMA1oWx lGhbE7PjYbYh3R1p6j+s+BCEHGm+09V72PG3R4PX+k556O2ocPZ6aOADsiJWW4KS1jwO Xgzl2ZsoFlHAyvjkv18MauatStcS8q4m5jLnQ/Pw0lw6oGCzIfPDQJJaxzSahEeTksxj UDcO5+N2yHUHotM51fWIpGflsXMEYdnqgNiucGVyVNwlam8hrr7TN89pTLZnhgSCiniy Ghahq2SmLHlJn31t/fTV6lKM9Z/ECvFwCRZ1YqCOOksxVkSMU7vRXuF3Q822+nDZezIZ VlWQ== X-Gm-Message-State: APjAAAXw67ANmAQJvUTBetc1/o8fq+JFpj3iYCXnyVd4Kd+Qe5yLDvkg NswCzM5PfOFjQDfhiAo544yANy2DyNy1DpGIHAkEvw== X-Google-Smtp-Source: APXvYqyjnlsGnir4nPy3hMLpW07ohKztD3RxPsYLY3A/Sa4cuV8dEjDRbdbOmPFer08xkz1jJqjDaeOS+XOGyZFIuh1wyA== X-Received: by 2002:a37:90c2:: with SMTP id s185mr11369315qkd.161.1565222903745; Wed, 07 Aug 2019 17:08:23 -0700 (PDT) Date: Wed, 7 Aug 2019 17:07:15 -0700 In-Reply-To: <20190808000721.124691-1-matthewgarrett@google.com> Message-Id: <20190808000721.124691-24-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190808000721.124691-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.770.g0f2c4a37fd-goog Subject: [PATCH V38 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, David Howells , Alexei Starovoitov , Matthew Garrett , Kees Cook , netdev@vger.kernel.org, Chun-Yi Lee , Daniel Borkmann Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: David Howells bpf_read() and bpf_read_str() could potentially be abused to (eg) allow private keys in kernel memory to be leaked. Disable them if the kernel has been locked down in confidentiality mode. Suggested-by: Alexei Starovoitov Signed-off-by: Matthew Garrett Reviewed-by: Kees Cook cc: netdev@vger.kernel.org cc: Chun-Yi Lee cc: Alexei Starovoitov Cc: Daniel Borkmann --- include/linux/security.h | 1 + kernel/trace/bpf_trace.c | 10 ++++++++++ security/lockdown/lockdown.c | 1 + 3 files changed, 12 insertions(+) diff --git a/include/linux/security.h b/include/linux/security.h index 987d8427f091..8dd1741a52cd 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -118,6 +118,7 @@ enum lockdown_reason { LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_KCORE, LOCKDOWN_KPROBES, + LOCKDOWN_BPF_READ, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index ca1255d14576..492a8bfaae98 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -142,8 +142,13 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr) { int ret; + ret = security_locked_down(LOCKDOWN_BPF_READ); + if (ret < 0) + goto out; + ret = probe_kernel_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) +out: memset(dst, 0, size); return ret; @@ -569,6 +574,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, { int ret; + ret = security_locked_down(LOCKDOWN_BPF_READ); + if (ret < 0) + goto out; + /* * The strncpy_from_unsafe() call will likely not fill the entire * buffer, but that's okay in this circumstance as we're probing @@ -580,6 +589,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, */ ret = strncpy_from_unsafe(dst, unsafe_ptr, size); if (unlikely(ret < 0)) +out: memset(dst, 0, size); return ret; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 6b123cbf3748..1b89d3e8e54d 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -33,6 +33,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_KCORE] = "/proc/kcore access", [LOCKDOWN_KPROBES] = "use of kprobes", + [LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };