From patchwork Fri Jun 21 01:19:35 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 1119901 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="NugahSiL"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 45VLVK2Pjlz9sBp for ; Fri, 21 Jun 2019 11:20:57 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726865AbfFUBUv (ORCPT ); Thu, 20 Jun 2019 21:20:51 -0400 Received: from mail-vs1-f74.google.com ([209.85.217.74]:53871 "EHLO mail-vs1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726825AbfFUBUt (ORCPT ); Thu, 20 Jun 2019 21:20:49 -0400 Received: by mail-vs1-f74.google.com with SMTP id b23so1579647vsl.20 for ; Thu, 20 Jun 2019 18:20:48 -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=X+spaxNTDtzOavXCOZulSz3gCHiK1Z4KEx0/1FYpsLk=; b=NugahSiL2+bnOfMwUtvTk1vSDUneqRD5E8fRNkev54yO8MjHUAYtCZcXnwDXRco4La UFl5CnSb5dD8DD4U789xI0KNrSSQje+FVCx45vSBOz3vTlYXTKM6BwsgWYIk1ETyJuvN EynNdlcRb3NSOJwAQliPiGGQy28uDvhZoX/7+No9Tzsy9HKIMLUO7HllrePlbiUX4VW+ eD9xwTf1I1qO2cGjk4TdJy0C23Z+amOWALITnlzcXREgAmSUY2Ze7ULEF99fEgW8Hfl8 VAz1jm7oMRaOO2y3Svh5KYQaulmBVXFwUdgxDxCiuqDewNPMOzJvL//l84t5T1Gy5XGb L80A== 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=X+spaxNTDtzOavXCOZulSz3gCHiK1Z4KEx0/1FYpsLk=; b=MLl0uKX27y1j0kLnkjRYLmskSkaLKhMfFfnttKdrqJ8Bra8NNpie1ts6M3F/7/WkLS AoqXwV2yamdIUnh2C3JtdTcrWSkOA25WsQrIFsv+6hnQLcRtvpkNxbR6PpoHh8BDbeNj dySFWRHj9M+8WPxj1HfPIkcFLrjt0BuRqqvtNzEOaYLGFS4J0DXoTnlUJr3/qRIQwnza x+B8JQ6cr95FFaFAYRBB7y6GwDNM24e0k1th5gUNhSoHH7D0UKwZktoU4HB9m8q65HNd unKlRIQmApNsbq9/W2tVyq7OZtDvS/JhrNanUFr3ZQMOiuRdzPSM6fY5C8hDuETHH/Wm Oubw== X-Gm-Message-State: APjAAAXseygWvCt2ewJhUsU5xvW+uJTF6CinKZAPWoyo1w0EVIbzCi0k YQlZNbZyD0WM3lFwr7wLTaghCApeRgXUmBFK335LAA== X-Google-Smtp-Source: APXvYqz7/NyB5Bpb1MhjrsX/EgPgT30NqAjjYQ0wa371R9qc7apPIh2E50x4AdbbuF+LN/gv42YCUtCqKf7SOI+rw/5rnA== X-Received: by 2002:a67:f6d4:: with SMTP id v20mr58900267vso.174.1561080048229; Thu, 20 Jun 2019 18:20:48 -0700 (PDT) Date: Thu, 20 Jun 2019 18:19:35 -0700 In-Reply-To: <20190621011941.186255-1-matthewgarrett@google.com> Message-Id: <20190621011941.186255-25-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190621011941.186255-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH V33 24/30] bpf: Restrict bpf when kernel lockdown is in confidentiality mode From: Matthew Garrett To: jmorris@namei.org Cc: linux-security@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, David Howells , Alexei Starovoitov , Matthew Garrett , netdev@vger.kernel.org, Chun-Yi Lee , Daniel Borkmann Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: David Howells There are some bpf functions can be used to read kernel memory: bpf_probe_read, bpf_probe_write_user and bpf_trace_printk. These allow private keys in kernel memory (e.g. the hibernation image signing key) to be read by an eBPF program and kernel memory to be altered without restriction. Disable them if the kernel has been locked down in confidentiality mode. Suggested-by: Alexei Starovoitov Signed-off-by: David Howells Signed-off-by: Matthew Garrett 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 | 11 +++++++++++ security/lockdown/lockdown.c | 1 + 3 files changed, 13 insertions(+) diff --git a/include/linux/security.h b/include/linux/security.h index dae4aa83352c..8bf426cdd151 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -97,6 +97,7 @@ enum lockdown_reason { LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_KCORE, LOCKDOWN_KPROBES, + LOCKDOWN_BPF, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d64c00afceb5..6f57485df840 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -137,6 +137,9 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr) { int ret; + if (security_is_locked_down(LOCKDOWN_BPF)) + return -EINVAL; + ret = probe_kernel_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) memset(dst, 0, size); @@ -156,6 +159,8 @@ static const struct bpf_func_proto bpf_probe_read_proto = { BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, u32, size) { + if (security_is_locked_down(LOCKDOWN_BPF)) + return -EINVAL; /* * Ensure we're in user context which is safe for the helper to * run. This helper has no business in a kthread. @@ -207,6 +212,9 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, char buf[64]; int i; + if (security_is_locked_down(LOCKDOWN_BPF)) + return -EINVAL; + /* * bpf_check()->check_func_arg()->check_stack_boundary() * guarantees that fmt points to bpf program stack, @@ -534,6 +542,9 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, { int ret; + if (security_is_locked_down(LOCKDOWN_BPF)) + return -EINVAL; + /* * The strncpy_from_unsafe() call will likely not fill the entire * buffer, but that's okay in this circumstance as we're probing diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 89ad853daec2..0a3bbf1ba01d 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] = "use of bpf", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };