From patchwork Sat Dec 10 18:56:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mauricio Faria de Oliveira X-Patchwork-Id: 9469413 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B557F60231 for ; Sat, 10 Dec 2016 18:56:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AA75828427 for ; Sat, 10 Dec 2016 18:56:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9F27F2846E; Sat, 10 Dec 2016 18:56:37 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable 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 DD04A28446 for ; Sat, 10 Dec 2016 18:56:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752765AbcLJS4Y (ORCPT ); Sat, 10 Dec 2016 13:56:24 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:45486 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752656AbcLJS4V (ORCPT ); Sat, 10 Dec 2016 13:56:21 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uBAIsCUg066275 for ; Sat, 10 Dec 2016 13:56:15 -0500 Received: from e24smtp01.br.ibm.com (e24smtp01.br.ibm.com [32.104.18.85]) by mx0a-001b2d01.pphosted.com with ESMTP id 278g9u4tda-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Sat, 10 Dec 2016 13:56:15 -0500 Received: from localhost by e24smtp01.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Sat, 10 Dec 2016 16:56:10 -0200 Received: from d24relay04.br.ibm.com (d24relay04.br.ibm.com [9.18.232.146]) by d24dlp01.br.ibm.com (Postfix) with ESMTP id 2DE10352005C; Sat, 10 Dec 2016 13:55:39 -0500 (EST) Received: from d24av01.br.ibm.com (d24av01.br.ibm.com [9.8.31.91]) by d24relay04.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id uBAIu9vh63832138; Sat, 10 Dec 2016 16:56:09 -0200 Received: from d24av01.br.ibm.com (localhost [127.0.0.1]) by d24av01.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id uBAIu924028656; Sat, 10 Dec 2016 16:56:09 -0200 Received: from localhost.localdomain (p8le03.aus.stglabs.ibm.com [9.40.195.132]) by d24av01.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id uBAIu7Qs028653; Sat, 10 Dec 2016 16:56:07 -0200 From: Mauricio Faria de Oliveira To: axboe@kernel.dk, linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org, pbonzini@redhat.com Subject: [PATCH] block: allow WRITE_SAME commands with the SG_IO ioctl Date: Sat, 10 Dec 2016 12:56:06 -0600 X-Mailer: git-send-email 2.7.4 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16121018-1523-0000-0000-00000257703F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16121018-1524-0000-0000-000029E0FE14 Message-Id: <1481396166-8134-1-git-send-email-mauricfo@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2016-12-10_13:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1612100254 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The WRITE_SAME commands are not present in the blk_default_cmd_filter write_ok list, and thus are failed with -EPERM when the SG_IO ioctl() is executed without CAP_SYS_RAWIO capability (e.g., unprivileged users). [ sg_io() -> blk_fill_sghdr_rq() > blk_verify_command() -> -EPERM ] The problem can be reproduced with the sg_write_same command # sg_write_same --num 1 --xferlen 512 /dev/sda # # capsh --drop=cap_sys_rawio -- -c \ 'sg_write_same --num 1 --xferlen 512 /dev/sda' Write same: pass through os error: Operation not permitted # For comparison, the WRITE_VERIFY command does not observe this problem, since it is in that list: # capsh --drop=cap_sys_rawio -- -c \ 'sg_write_verify --num 1 --ilen 512 --lba 0 /dev/sda' # So, this patch adds the WRITE_SAME commands to the list, in order for the SG_IO ioctl to finish successfully: # capsh --drop=cap_sys_rawio -- -c \ 'sg_write_same --num 1 --xferlen 512 /dev/sda' # That case happens to be exercised by QEMU KVM guests with 'scsi-block' devices (qemu "-device scsi-block" [1], libvirt "" [2]), which employs the SG_IO ioctl() and runs as an unprivileged user (libvirt-qemu). In that scenario, when a filesystem (e.g., ext4) performs its zero-out calls, which are translated to write-same calls in the guest kernel, and then into SG_IO ioctls to the host kernel, SCSI I/O errors may be observed in the guest: [...] sd 0:0:0:0: [sda] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [...] sd 0:0:0:0: [sda] tag#0 Sense Key : Aborted Command [current] [...] sd 0:0:0:0: [sda] tag#0 Add. Sense: I/O process terminated [...] sd 0:0:0:0: [sda] tag#0 CDB: Write Same(10) 41 00 01 04 e0 78 00 00 08 00 [...] blk_update_request: I/O error, dev sda, sector 17096824 Links: [1] http://git.qemu.org/?p=qemu.git;a=commit;h=336a6915bc7089fb20fea4ba99972ad9a97c5f52 [2] https://libvirt.org/formatdomain.html#elementsDisks (see 'disk' -> 'device') Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Brahadambal Srinivasan Reported-by: Manjunatha H R --- block/scsi_ioctl.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c index 0774799..c6fee74 100644 --- a/block/scsi_ioctl.c +++ b/block/scsi_ioctl.c @@ -182,6 +182,9 @@ static void blk_set_cmd_filter_defaults(struct blk_cmd_filter *filter) __set_bit(WRITE_16, filter->write_ok); __set_bit(WRITE_LONG, filter->write_ok); __set_bit(WRITE_LONG_2, filter->write_ok); + __set_bit(WRITE_SAME, filter->write_ok); + __set_bit(WRITE_SAME_16, filter->write_ok); + __set_bit(WRITE_SAME_32, filter->write_ok); __set_bit(ERASE, filter->write_ok); __set_bit(GPCMD_MODE_SELECT_10, filter->write_ok); __set_bit(MODE_SELECT, filter->write_ok);