From patchwork Mon Jul 12 06:02:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 475904 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 40562C07E9B for ; Mon, 12 Jul 2021 06:58:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A5746141F for ; Mon, 12 Jul 2021 06:58:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239771AbhGLHAu (ORCPT ); Mon, 12 Jul 2021 03:00:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:34544 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242360AbhGLHAC (ORCPT ); Mon, 12 Jul 2021 03:00:02 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C515A61156; Mon, 12 Jul 2021 06:57:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626073033; bh=tEL3krEBJM2K5rNwIGUtcm5FIQQZgrqjaj/HQA/dPiI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T+plEQALAJm8GzGplHXuAJSMCpLi/fiKgSZbhPkUisHeOgzEyUNL1Y/Qw05BLn1cl rO6xs7bB3+4zibRhmXEIKECyb6hDnWwEgJrYHZH7NhWIarJLKdOXUyOXIAI9ke0O9B UPDa2yPmMKPyRWYWAFDEC0WsAFjBnB2hQHt5wTCI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Janosch Frank , Christian Borntraeger , Vasily Gorbik Subject: [PATCH 5.12 077/700] s390: mm: Fix secure storage access exception handling Date: Mon, 12 Jul 2021 08:02:40 +0200 Message-Id: <20210712060935.578094165@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060924.797321836@linuxfoundation.org> References: <20210712060924.797321836@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Janosch Frank commit 85b18d7b5e7ffefb2f076186511d39c4990aa005 upstream. Turns out that the bit 61 in the TEID is not always 1 and if that's the case the address space ID and the address are unpredictable. Without an address and its address space ID we can't export memory and hence we can only send a SIGSEGV to the process or panic the kernel depending on who caused the exception. Unfortunately bit 61 is only reliable if we have the "misc" UV feature bit. Signed-off-by: Janosch Frank Reviewed-by: Christian Borntraeger Fixes: 084ea4d611a3d ("s390/mm: add (non)secure page access exceptions handlers") Cc: stable@vger.kernel.org Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman --- arch/s390/boot/uv.c | 1 + arch/s390/include/asm/uv.h | 8 +++++++- arch/s390/kernel/uv.c | 10 ++++++++++ arch/s390/mm/fault.c | 26 ++++++++++++++++++++++++++ 4 files changed, 44 insertions(+), 1 deletion(-) --- a/arch/s390/boot/uv.c +++ b/arch/s390/boot/uv.c @@ -36,6 +36,7 @@ void uv_query_info(void) uv_info.max_sec_stor_addr = ALIGN(uvcb.max_guest_stor_addr, PAGE_SIZE); uv_info.max_num_sec_conf = uvcb.max_num_sec_conf; uv_info.max_guest_cpu_id = uvcb.max_guest_cpu_id; + uv_info.uv_feature_indications = uvcb.uv_feature_indications; } #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST --- a/arch/s390/include/asm/uv.h +++ b/arch/s390/include/asm/uv.h @@ -73,6 +73,10 @@ enum uv_cmds_inst { BIT_UVC_CMD_UNPIN_PAGE_SHARED = 22, }; +enum uv_feat_ind { + BIT_UV_FEAT_MISC = 0, +}; + struct uv_cb_header { u16 len; u16 cmd; /* Command Code */ @@ -97,7 +101,8 @@ struct uv_cb_qui { u64 max_guest_stor_addr; u8 reserved88[158 - 136]; u16 max_guest_cpu_id; - u8 reserveda0[200 - 160]; + u64 uv_feature_indications; + u8 reserveda0[200 - 168]; } __packed __aligned(8); /* Initialize Ultravisor */ @@ -274,6 +279,7 @@ struct uv_info { unsigned long max_sec_stor_addr; unsigned int max_num_sec_conf; unsigned short max_guest_cpu_id; + unsigned long uv_feature_indications; }; extern struct uv_info uv_info; --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -364,6 +364,15 @@ static ssize_t uv_query_facilities(struc static struct kobj_attribute uv_query_facilities_attr = __ATTR(facilities, 0444, uv_query_facilities, NULL); +static ssize_t uv_query_feature_indications(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%lx\n", uv_info.uv_feature_indications); +} + +static struct kobj_attribute uv_query_feature_indications_attr = + __ATTR(feature_indications, 0444, uv_query_feature_indications, NULL); + static ssize_t uv_query_max_guest_cpus(struct kobject *kobj, struct kobj_attribute *attr, char *page) { @@ -396,6 +405,7 @@ static struct kobj_attribute uv_query_ma static struct attribute *uv_query_attrs[] = { &uv_query_facilities_attr.attr, + &uv_query_feature_indications_attr.attr, &uv_query_max_guest_cpus_attr.attr, &uv_query_max_guest_vms_attr.attr, &uv_query_max_guest_addr_attr.attr, --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -791,6 +791,32 @@ void do_secure_storage_access(struct pt_ struct page *page; int rc; + /* + * bit 61 tells us if the address is valid, if it's not we + * have a major problem and should stop the kernel or send a + * SIGSEGV to the process. Unfortunately bit 61 is not + * reliable without the misc UV feature so we need to check + * for that as well. + */ + if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && + !test_bit_inv(61, ®s->int_parm_long)) { + /* + * When this happens, userspace did something that it + * was not supposed to do, e.g. branching into secure + * memory. Trigger a segmentation fault. + */ + if (user_mode(regs)) { + send_sig(SIGSEGV, current, 0); + return; + } + + /* + * The kernel should never run into this case and we + * have no way out of this situation. + */ + panic("Unexpected PGM 0x3d with TEID bit 61=0"); + } + switch (get_fault_type(regs)) { case USER_FAULT: mm = current->mm;