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[Qemu-devel] [PATCH v4 05/21] nbd/server: Hoist length check to qmp_nbd_
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH v4 05/21] nbd/server: Hoist length check to qmp_nbd_server_add |
Date: |
Thu, 17 Jan 2019 13:36:42 -0600 |
We only had two callers to nbd_export_new; qemu-nbd.c always
passed a valid offset/length pair (because it already checked
the file length, to ensure that offset was in bounds), while
blockdev-nbd.c always passed 0/-1. Then nbd_export_new reduces
the size to a multiple of BDRV_SECTOR_SIZE (can only happen
when offset is not sector-aligned, since bdrv_getlength()
currently rounds up), which can result in offset being greater
than the enforced length, but that's not fatal (the server
rejects client requests that exceed the advertised length).
However, I'm finding it easier to work with the code if we are
consistent on having both callers pass in a valid length, and
just assert that things are sane in nbd_export_new, meaning
that no negative values were passed, and that offset+size does
not exceed 63 bits (as that really is a fundamental limit to
later operations, whether we use off_t or uint64_t).
Signed-off-by: Eric Blake <address@hidden>
---
v4: rework asserts [Vladimir], retitle
v3: new patch
---
blockdev-nbd.c | 10 +++++++++-
nbd/server.c | 10 +++-------
2 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index c76d5416b90..d73ac1b026a 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -146,6 +146,7 @@ void qmp_nbd_server_add(const char *device, bool has_name,
const char *name,
BlockDriverState *bs = NULL;
BlockBackend *on_eject_blk;
NBDExport *exp;
+ int64_t len;
if (!nbd_server) {
error_setg(errp, "NBD server not running");
@@ -168,6 +169,13 @@ void qmp_nbd_server_add(const char *device, bool has_name,
const char *name,
return;
}
+ len = bdrv_getlength(bs);
+ if (len < 0) {
+ error_setg_errno(errp, -len,
+ "Failed to determine the NBD export's length");
+ return;
+ }
+
if (!has_writable) {
writable = false;
}
@@ -175,7 +183,7 @@ void qmp_nbd_server_add(const char *device, bool has_name,
const char *name,
writable = false;
}
- exp = nbd_export_new(bs, 0, -1, name, NULL, bitmap,
+ exp = nbd_export_new(bs, 0, len, name, NULL, bitmap,
writable ? 0 : NBD_FLAG_READ_ONLY,
NULL, false, on_eject_blk, errp);
if (!exp) {
diff --git a/nbd/server.c b/nbd/server.c
index 6b136019f82..51ee8094e02 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1495,17 +1495,13 @@ NBDExport *nbd_export_new(BlockDriverState *bs, off_t
dev_offset, off_t size,
exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->blk = blk;
+ assert(dev_offset >= 0 && dev_offset <= INT64_MAX);
exp->dev_offset = dev_offset;
exp->name = g_strdup(name);
exp->description = g_strdup(description);
exp->nbdflags = nbdflags;
- exp->size = size < 0 ? blk_getlength(blk) : size;
- if (exp->size < 0) {
- error_setg_errno(errp, -exp->size,
- "Failed to determine the NBD export's length");
- goto fail;
- }
- exp->size -= exp->size % BDRV_SECTOR_SIZE;
+ assert(size >= 0 && size <= INT64_MAX - dev_offset);
+ exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
if (bitmap) {
BdrvDirtyBitmap *bm = NULL;
--
2.20.1
- [Qemu-devel] [PATCH v4 00/21] nbd: add qemu-nbd --list, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 02/21] maint: Allow for EXAMPLES in texi2pod, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 01/21] iotests: Make 233 output more reliable, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 03/21] qemu-nbd: Enhance man page, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 04/21] qemu-nbd: Sanity check partition bounds, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 05/21] nbd/server: Hoist length check to qmp_nbd_server_add,
Eric Blake <=
- [Qemu-devel] [PATCH v4 06/21] nbd/server: Favor [u]int64_t over off_t, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 07/21] qemu-nbd: Avoid strtol open-coding, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 08/21] nbd/client: Refactor nbd_receive_list(), Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 09/21] nbd/client: Move export name into NBDExportInfo, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 15/21] nbd/client: Pull out oldstyle size determination, Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 11/21] nbd/client: Split out nbd_send_meta_query(), Eric Blake, 2019/01/17
- [Qemu-devel] [PATCH v4 20/21] nbd/client: Work around 3.0 bug for listing meta contexts, Eric Blake, 2019/01/17