From patchwork Mon Sep 26 13:16:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Lynch X-Patchwork-Id: 12988813 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59119C6FA83 for ; Mon, 26 Sep 2022 14:52:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235369AbiIZOwb (ORCPT ); Mon, 26 Sep 2022 10:52:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235062AbiIZOvv (ORCPT ); Mon, 26 Sep 2022 10:51:51 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DCC261A81B; Mon, 26 Sep 2022 06:18:40 -0700 (PDT) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 28QBwoWP008333; Mon, 26 Sep 2022 13:18:33 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=b0L/rHr7wJxSwUmlBbd8KH1Nfw5hzSaLYU+kSP9guUY=; b=BLhFFsFbY+qWjhl+SmGEQ01JNP1RI/hM38Z+n03zi5R5EGk3C0hhVP+QUFVFbw3DJzHM f02Ic78D0q8LzjdeUe5dXRdq6rHX8r/bY8cxLCYGXRyzVkTwWqFAXa79KcJBA6Z4Zm4k UNYoR305y9eRrVyAaQdClhk5rfQhCrQJzkzlNrBPcle1bQxKhz1HngxDPG9SfWzrgr81 EPz6d1r7hFiygd3siciaUUbjb0GxrR3kujT/77rV506QXIHP1BvE8/GZkjbLsaqF+3oM QMcCKQ+1TkyO6pdeOroq3K7KR3Qjp55WOKo8QOSsgcDSP5WpZtWpCX5Ial1vG0BZfP2C og== Received: from ppma05wdc.us.ibm.com (1b.90.2fa9.ip4.static.sl-reverse.com [169.47.144.27]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3jubpdtd4v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 26 Sep 2022 13:18:32 +0000 Received: from pps.filterd (ppma05wdc.us.ibm.com [127.0.0.1]) by ppma05wdc.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 28QD59ff028259; Mon, 26 Sep 2022 13:18:31 GMT Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by ppma05wdc.us.ibm.com with ESMTP id 3jssh9e2kt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 26 Sep 2022 13:18:31 +0000 Received: from smtpav05.dal12v.mail.ibm.com ([9.208.128.132]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 28QDIWmg13107818 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 26 Sep 2022 13:18:32 GMT Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C4F9A5806A; Mon, 26 Sep 2022 13:18:29 +0000 (GMT) Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AB23C5806D; Mon, 26 Sep 2022 13:18:29 +0000 (GMT) Received: from localhost (unknown [9.163.91.170]) by smtpav05.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 26 Sep 2022 13:18:29 +0000 (GMT) From: Nathan Lynch To: linuxppc-dev@lists.ozlabs.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Cc: jmorris@namei.org, mpe@ellerman.id.au, paul@paul-moore.com, serge@hallyn.com, ajd@linux.ibm.com, gcwilson@linux.ibm.com, nayna@linux.ibm.com Subject: [PATCH v2 2/2] powerpc/rtas: block error injection when locked down Date: Mon, 26 Sep 2022 08:16:43 -0500 Message-Id: <20220926131643.146502-3-nathanl@linux.ibm.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220926131643.146502-1-nathanl@linux.ibm.com> References: <20220926131643.146502-1-nathanl@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: W2RKvYiQGhxbrXPIQi98wuZld6lgDNUL X-Proofpoint-ORIG-GUID: W2RKvYiQGhxbrXPIQi98wuZld6lgDNUL X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-26_08,2022-09-22_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 impostorscore=0 mlxscore=0 bulkscore=0 suspectscore=0 priorityscore=1501 clxscore=1015 adultscore=0 mlxlogscore=999 malwarescore=0 phishscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2209130000 definitions=main-2209260083 Precedence: bulk List-ID: The error injection facility on pseries VMs allows corruption of arbitrary guest memory, potentially enabling a sufficiently privileged user to disable lockdown or perform other modifications of the running kernel via the rtas syscall. Block the PAPR error injection facility from being opened or called when locked down. Signed-off-by: Nathan Lynch Acked-by: Paul Moore (LSM) Reviewed-by: Andrew Donnellan --- arch/powerpc/kernel/rtas.c | 25 ++++++++++++++++++++++++- include/linux/security.h | 1 + security/security.c | 1 + 3 files changed, 26 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 693133972294..c2540d393f1c 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -464,6 +465,9 @@ void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, va_end(list); } +static int ibm_open_errinjct_token; +static int ibm_errinjct_token; + int rtas_call(int token, int nargs, int nret, int *outputs, ...) { va_list list; @@ -476,6 +480,16 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE) return -1; + if (token == ibm_open_errinjct_token || token == ibm_errinjct_token) { + /* + * It would be nicer to not discard the error value + * from security_locked_down(), but callers expect an + * RTAS status, not an errno. + */ + if (security_locked_down(LOCKDOWN_RTAS_ERROR_INJECTION)) + return -1; + } + if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) { WARN_ON_ONCE(1); return -1; @@ -1227,6 +1241,14 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) if (block_rtas_call(token, nargs, &args)) return -EINVAL; + if (token == ibm_open_errinjct_token || token == ibm_errinjct_token) { + int err; + + err = security_locked_down(LOCKDOWN_RTAS_ERROR_INJECTION); + if (err) + return err; + } + /* Need to handle ibm,suspend_me call specially */ if (token == rtas_token("ibm,suspend-me")) { @@ -1325,7 +1347,8 @@ void __init rtas_initialize(void) #ifdef CONFIG_RTAS_ERROR_LOGGING rtas_last_error_token = rtas_token("rtas-last-error"); #endif - + ibm_open_errinjct_token = rtas_token("ibm,open-errinjct"); + ibm_errinjct_token = rtas_token("ibm,errinjct"); rtas_syscall_filter_init(); } diff --git a/include/linux/security.h b/include/linux/security.h index 39e7c0e403d9..70f89dc3a712 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -123,6 +123,7 @@ enum lockdown_reason { LOCKDOWN_XMON_WR, LOCKDOWN_BPF_WRITE_USER, LOCKDOWN_DBG_WRITE_KERNEL, + LOCKDOWN_RTAS_ERROR_INJECTION, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_KCORE, LOCKDOWN_KPROBES, diff --git a/security/security.c b/security/security.c index 51bf66d4f472..eabe3ce7e74e 100644 --- a/security/security.c +++ b/security/security.c @@ -61,6 +61,7 @@ const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_XMON_WR] = "xmon write access", [LOCKDOWN_BPF_WRITE_USER] = "use of bpf to write user RAM", [LOCKDOWN_DBG_WRITE_KERNEL] = "use of kgdb/kdb to write kernel RAM", + [LOCKDOWN_RTAS_ERROR_INJECTION] = "RTAS error injection", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_KCORE] = "/proc/kcore access", [LOCKDOWN_KPROBES] = "use of kprobes",