From patchwork Fri Oct 11 15:28:02 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 11185747 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4672714DB for ; Fri, 11 Oct 2019 15:34:54 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2750E206CD for ; Fri, 11 Oct 2019 15:34:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2750E206CD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:52270 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwwP-0007sE-0K for patchwork-qemu-devel@patchwork.kernel.org; Fri, 11 Oct 2019 11:34:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57737) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwqJ-0001RS-HF for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iIwqI-0006UM-1r for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38058) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iIwqE-0006RO-CW; Fri, 11 Oct 2019 11:28:30 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9F7AD300CB26; Fri, 11 Oct 2019 15:28:29 +0000 (UTC) Received: from localhost (ovpn-116-40.ams2.redhat.com [10.36.116.40]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E50E310013D9; Fri, 11 Oct 2019 15:28:28 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v3 04/16] qcow2: Keep unknown extra snapshot data Date: Fri, 11 Oct 2019 17:28:02 +0200 Message-Id: <20191011152814.14791-5-mreitz@redhat.com> In-Reply-To: <20191011152814.14791-1-mreitz@redhat.com> References: <20191011152814.14791-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Fri, 11 Oct 2019 15:28:29 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" The qcow2 specification says to ignore unknown extra data fields in snapshot table entries. Currently, we discard it whenever we update the image, which is a bit different from "ignore". This patch makes the qcow2 driver keep all unknown extra data fields when updating an image's snapshot table. Signed-off-by: Max Reitz Reviewed-by: Eric Blake --- block/qcow2.h | 5 ++++ block/qcow2-snapshot.c | 61 +++++++++++++++++++++++++++++++++++------- 2 files changed, 56 insertions(+), 10 deletions(-) diff --git a/block/qcow2.h b/block/qcow2.h index 8da1ad11d9..61e5d4ba94 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -61,6 +61,9 @@ * space for snapshot names and IDs */ #define QCOW_MAX_SNAPSHOTS_SIZE (1024 * QCOW_MAX_SNAPSHOTS) +/* Maximum amount of extra data per snapshot table entry to accept */ +#define QCOW_MAX_SNAPSHOT_EXTRA_DATA 1024 + /* Bitmap header extension constraints */ #define QCOW2_MAX_BITMAPS 65535 #define QCOW2_MAX_BITMAP_DIRECTORY_SIZE (1024 * QCOW2_MAX_BITMAPS) @@ -181,6 +184,8 @@ typedef struct QCowSnapshot { uint32_t date_sec; uint32_t date_nsec; uint64_t vm_clock_nsec; + uint32_t extra_data_size; + void *unknown_extra_data; /* Extra data past QCowSnapshotExtraData */ } QCowSnapshot; struct Qcow2Cache; diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 80d32e4504..120cb7fa09 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -37,6 +37,7 @@ void qcow2_free_snapshots(BlockDriverState *bs) for(i = 0; i < s->nb_snapshots; i++) { g_free(s->snapshots[i].name); g_free(s->snapshots[i].id_str); + g_free(s->snapshots[i].unknown_extra_data); } g_free(s->snapshots); s->snapshots = NULL; @@ -51,7 +52,6 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) QCowSnapshot *sn; int i, id_str_size, name_size; int64_t offset; - uint32_t extra_data_size; int ret; if (!s->nb_snapshots) { @@ -80,31 +80,53 @@ int qcow2_read_snapshots(BlockDriverState *bs, Error **errp) sn->date_sec = be32_to_cpu(h.date_sec); sn->date_nsec = be32_to_cpu(h.date_nsec); sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec); - extra_data_size = be32_to_cpu(h.extra_data_size); + sn->extra_data_size = be32_to_cpu(h.extra_data_size); id_str_size = be16_to_cpu(h.id_str_size); name_size = be16_to_cpu(h.name_size); - /* Read extra data */ + if (sn->extra_data_size > QCOW_MAX_SNAPSHOT_EXTRA_DATA) { + ret = -EFBIG; + error_setg(errp, "Too much extra metadata in snapshot table " + "entry %i", i); + goto fail; + } + + /* Read known extra data */ ret = bdrv_pread(bs->file, offset, &extra, - MIN(sizeof(extra), extra_data_size)); + MIN(sizeof(extra), sn->extra_data_size)); if (ret < 0) { error_setg_errno(errp, -ret, "Failed to read snapshot table"); goto fail; } - offset += extra_data_size; + offset += MIN(sizeof(extra), sn->extra_data_size); - if (extra_data_size >= endof(QCowSnapshotExtraData, - vm_state_size_large)) { + if (sn->extra_data_size >= endof(QCowSnapshotExtraData, + vm_state_size_large)) { sn->vm_state_size = be64_to_cpu(extra.vm_state_size_large); } - if (extra_data_size >= endof(QCowSnapshotExtraData, disk_size)) { + if (sn->extra_data_size >= endof(QCowSnapshotExtraData, disk_size)) { sn->disk_size = be64_to_cpu(extra.disk_size); } else { sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE; } + if (sn->extra_data_size > sizeof(extra)) { + /* Store unknown extra data */ + size_t unknown_extra_data_size = + sn->extra_data_size - sizeof(extra); + + sn->unknown_extra_data = g_malloc(unknown_extra_data_size); + ret = bdrv_pread(bs->file, offset, sn->unknown_extra_data, + unknown_extra_data_size); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to read snapshot table"); + goto fail; + } + offset += unknown_extra_data_size; + } + /* Read snapshot ID */ sn->id_str = g_malloc(id_str_size + 1); ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size); @@ -162,7 +184,7 @@ static int qcow2_write_snapshots(BlockDriverState *bs) sn = s->snapshots + i; offset = ROUND_UP(offset, 8); offset += sizeof(h); - offset += sizeof(extra); + offset += MAX(sizeof(extra), sn->extra_data_size); offset += strlen(sn->id_str); offset += strlen(sn->name); @@ -209,7 +231,8 @@ static int qcow2_write_snapshots(BlockDriverState *bs) h.date_sec = cpu_to_be32(sn->date_sec); h.date_nsec = cpu_to_be32(sn->date_nsec); h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec); - h.extra_data_size = cpu_to_be32(sizeof(extra)); + h.extra_data_size = cpu_to_be32(MAX(sizeof(extra), + sn->extra_data_size)); memset(&extra, 0, sizeof(extra)); extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size); @@ -234,6 +257,22 @@ static int qcow2_write_snapshots(BlockDriverState *bs) } offset += sizeof(extra); + if (sn->extra_data_size > sizeof(extra)) { + size_t unknown_extra_data_size = + sn->extra_data_size - sizeof(extra); + + /* qcow2_read_snapshots() ensures no unbounded allocation */ + assert(unknown_extra_data_size <= BDRV_REQUEST_MAX_BYTES); + assert(sn->unknown_extra_data); + + ret = bdrv_pwrite(bs->file, offset, sn->unknown_extra_data, + unknown_extra_data_size); + if (ret < 0) { + goto fail; + } + offset += unknown_extra_data_size; + } + ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size); if (ret < 0) { goto fail; @@ -376,6 +415,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) sn->date_sec = sn_info->date_sec; sn->date_nsec = sn_info->date_nsec; sn->vm_clock_nsec = sn_info->vm_clock_nsec; + sn->extra_data_size = sizeof(QCowSnapshotExtraData); /* Allocate the L1 table of the snapshot and copy the current one there. */ l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t)); @@ -647,6 +687,7 @@ int qcow2_snapshot_delete(BlockDriverState *bs, * The snapshot is now unused, clean up. If we fail after this point, we * won't recover but just leak clusters. */ + g_free(sn.unknown_extra_data); g_free(sn.id_str); g_free(sn.name);