From 1a848fd4517820981b542e0d10e64c0426414229 Mon Sep 17 00:00:00 2001 From: Jeff Cody Date: Wed, 30 Oct 2013 10:44:46 -0400 Subject: [PATCH] block: vhdx - add region overlap detection for image files Regions in the image file cannot overlap - the log, region tables, and metdata must all be unique and non-overlapping. This adds region checking by means of a QLIST; there can be a variable number of regions and metadata (there may be metadata or region tables that we do not recognize / know about, but are not required). This adds the capability to register a region for later checking, and to check against registered regions for any overlap. Also, if neither the BAT or Metadata region tables are found, return error. Signed-off-by: Jeff Cody Signed-off-by: Stefan Hajnoczi --- block/vhdx.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++ block/vhdx.h | 9 ++++++ 2 files changed, 91 insertions(+) diff --git a/block/vhdx.c b/block/vhdx.c index 8fbfbd60a1..574ac4c931 100644 --- a/block/vhdx.c +++ b/block/vhdx.c @@ -204,6 +204,50 @@ void vhdx_guid_generate(MSGUID *guid) memcpy(guid, uuid, sizeof(MSGUID)); } +/* Check for region overlaps inside the VHDX image */ +static int vhdx_region_check(BDRVVHDXState *s, uint64_t start, uint64_t length) +{ + int ret = 0; + uint64_t end; + VHDXRegionEntry *r; + + end = start + length; + QLIST_FOREACH(r, &s->regions, entries) { + if (!((start >= r->end) || (end <= r->start))) { + ret = -EINVAL; + goto exit; + } + } + +exit: + return ret; +} + +/* Register a region for future checks */ +static void vhdx_region_register(BDRVVHDXState *s, + uint64_t start, uint64_t length) +{ + VHDXRegionEntry *r; + + r = g_malloc0(sizeof(*r)); + + r->start = start; + r->end = start + length; + + QLIST_INSERT_HEAD(&s->regions, r, entries); +} + +/* Free all registered regions */ +static void vhdx_region_unregister_all(BDRVVHDXState *s) +{ + VHDXRegionEntry *r, *r_next; + + QLIST_FOREACH_SAFE(r, &s->regions, entries, r_next) { + QLIST_REMOVE(r, entries); + g_free(r); + } +} + /* * Per the MS VHDX Specification, for every VHDX file: * - The header section is fixed size - 1 MB @@ -389,6 +433,9 @@ static int vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s) } } + vhdx_region_register(s, s->headers[s->curr_header]->log_offset, + s->headers[s->curr_header]->log_length); + ret = 0; goto exit; @@ -452,6 +499,15 @@ static int vhdx_open_region_tables(BlockDriverState *bs, BDRVVHDXState *s) le32_to_cpus(&rt_entry.length); le32_to_cpus(&rt_entry.data_bits); + /* check for region overlap between these entries, and any + * other memory regions in the file */ + ret = vhdx_region_check(s, rt_entry.file_offset, rt_entry.length); + if (ret < 0) { + goto fail; + } + + vhdx_region_register(s, rt_entry.file_offset, rt_entry.length); + /* see if we recognize the entry */ if (guid_eq(rt_entry.guid, bat_guid)) { /* must be unique; if we have already found it this is invalid */ @@ -482,6 +538,12 @@ static int vhdx_open_region_tables(BlockDriverState *bs, BDRVVHDXState *s) goto fail; } } + + if (!bat_rt_found || !metadata_rt_found) { + ret = -EINVAL; + goto fail; + } + ret = 0; fail: @@ -751,6 +813,7 @@ static void vhdx_close(BlockDriverState *bs) error_free(s->migration_blocker); qemu_vfree(s->log.hdr); s->log.hdr = NULL; + vhdx_region_unregister_all(s); } static int vhdx_open(BlockDriverState *bs, QDict *options, int flags, @@ -768,6 +831,7 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags, s->first_visible_write = true; qemu_co_mutex_init(&s->lock); + QLIST_INIT(&s->regions); /* validate the file signature */ ret = bdrv_pread(bs->file, 0, &signature, sizeof(uint64_t)); @@ -842,8 +906,26 @@ static int vhdx_open(BlockDriverState *bs, QDict *options, int flags, goto fail; } + uint64_t payblocks = s->chunk_ratio; + /* endian convert, and verify populated BAT field file offsets against + * region table and log entries */ for (i = 0; i < s->bat_entries; i++) { le64_to_cpus(&s->bat[i]); + if (payblocks--) { + /* payload bat entries */ + if ((s->bat[i] & VHDX_BAT_STATE_BIT_MASK) == + PAYLOAD_BLOCK_FULL_PRESENT) { + ret = vhdx_region_check(s, s->bat[i] & VHDX_BAT_FILE_OFF_MASK, + s->block_size); + if (ret < 0) { + goto fail; + } + } + } else { + payblocks = s->chunk_ratio; + /* Once differencing files are supported, verify sector bitmap + * blocks here */ + } } if (flags & BDRV_O_RDWR) { diff --git a/block/vhdx.h b/block/vhdx.h index 584ebec8fc..d9065595fc 100644 --- a/block/vhdx.h +++ b/block/vhdx.h @@ -230,6 +230,7 @@ typedef struct QEMU_PACKED VHDXLogDataSector { other bits are reserved */ #define VHDX_BAT_STATE_BIT_MASK 0x07 #define VHDX_BAT_FILE_OFF_BITS (64 - 44) +#define VHDX_BAT_FILE_OFF_MASK 0xFFFFFFFFFFF00000 /* upper 44 bits */ typedef uint64_t VHDXBatEntry; /* ---- METADATA REGION STRUCTURES ---- */ @@ -334,6 +335,12 @@ typedef struct VHDXLogEntries { uint32_t tail; } VHDXLogEntries; +typedef struct VHDXRegionEntry { + uint64_t start; + uint64_t end; + QLIST_ENTRY(VHDXRegionEntry) entries; +} VHDXRegionEntry; + typedef struct BDRVVHDXState { CoMutex lock; @@ -374,6 +381,8 @@ typedef struct BDRVVHDXState { VHDXParentLocatorEntry *parent_entries; Error *migration_blocker; + + QLIST_HEAD(VHDXRegionHead, VHDXRegionEntry) regions; } BDRVVHDXState; void vhdx_guid_generate(MSGUID *guid); -- GitLab