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[PATCH v7 02/12] nbd/server: Prepare to receive extended header requests
From: |
Eric Blake |
Subject: |
[PATCH v7 02/12] nbd/server: Prepare to receive extended header requests |
Date: |
Mon, 25 Sep 2023 14:22:32 -0500 |
Although extended mode is not yet enabled, once we do turn it on, we
need to accept extended requests for all messages. Previous patches
have already taken care of supporting 64-bit lengths, now we just need
to read it off the wire.
Note that this implementation will block indefinitely on a buggy
client that sends a non-extended payload (that is, we try to read a
full packet before we ever check the magic number, but a client that
mistakenly sends a simple request after negotiating extended headers
doesn't send us enough bytes), but it's no different from any other
client that stops talking to us partway through a packet and thus not
worth coding around.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
v6: fix sign extension bug
v5: no change
v4: new patch, split out from v3 9/14
---
nbd/nbd-internal.h | 5 ++++-
nbd/server.c | 43 ++++++++++++++++++++++++++++++-------------
2 files changed, 34 insertions(+), 14 deletions(-)
diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index 133b1d94b50..dfa02f77ee4 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -34,8 +34,11 @@
* https://github.com/yoe/nbd/blob/master/doc/proto.md
*/
-/* Size of all NBD_OPT_*, without payload */
+/* Size of all compact NBD_CMD_*, without payload */
#define NBD_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 4)
+/* Size of all extended NBD_CMD_*, without payload */
+#define NBD_EXTENDED_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 8)
+
/* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */
#define NBD_REPLY_SIZE (4 + 4 + 8)
/* Size of reply to NBD_OPT_EXPORT_NAME */
diff --git a/nbd/server.c b/nbd/server.c
index 1eabcfc908d..e227e470d41 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1411,11 +1411,13 @@ nbd_read_eof(NBDClient *client, void *buffer, size_t
size, Error **errp)
static int coroutine_fn nbd_receive_request(NBDClient *client, NBDRequest
*request,
Error **errp)
{
- uint8_t buf[NBD_REQUEST_SIZE];
- uint32_t magic;
+ uint8_t buf[NBD_EXTENDED_REQUEST_SIZE];
+ uint32_t magic, expect;
int ret;
+ size_t size = client->mode >= NBD_MODE_EXTENDED ?
+ NBD_EXTENDED_REQUEST_SIZE : NBD_REQUEST_SIZE;
- ret = nbd_read_eof(client, buf, sizeof(buf), errp);
+ ret = nbd_read_eof(client, buf, size, errp);
if (ret < 0) {
return ret;
}
@@ -1423,13 +1425,21 @@ static int coroutine_fn nbd_receive_request(NBDClient
*client, NBDRequest *reque
return -EIO;
}
- /* Request
- [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
- [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
- [ 6 .. 7] type (NBD_CMD_READ, ...)
- [ 8 .. 15] cookie
- [16 .. 23] from
- [24 .. 27] len
+ /*
+ * Compact request
+ * [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
+ * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
+ * [ 6 .. 7] type (NBD_CMD_READ, ...)
+ * [ 8 .. 15] cookie
+ * [16 .. 23] from
+ * [24 .. 27] len
+ * Extended request
+ * [ 0 .. 3] magic (NBD_EXTENDED_REQUEST_MAGIC)
+ * [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, NBD_CMD_FLAG_PAYLOAD_LEN, ...)
+ * [ 6 .. 7] type (NBD_CMD_READ, ...)
+ * [ 8 .. 15] cookie
+ * [16 .. 23] from
+ * [24 .. 31] len
*/
magic = ldl_be_p(buf);
@@ -1437,13 +1447,20 @@ static int coroutine_fn nbd_receive_request(NBDClient
*client, NBDRequest *reque
request->type = lduw_be_p(buf + 6);
request->cookie = ldq_be_p(buf + 8);
request->from = ldq_be_p(buf + 16);
- request->len = (uint32_t)ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+ if (client->mode >= NBD_MODE_EXTENDED) {
+ request->len = ldq_be_p(buf + 24);
+ expect = NBD_EXTENDED_REQUEST_MAGIC;
+ } else {
+ request->len = (uint32_t)ldl_be_p(buf + 24); /* widen 32 to 64 bits */
+ expect = NBD_REQUEST_MAGIC;
+ }
trace_nbd_receive_request(magic, request->flags, request->type,
request->from, request->len);
- if (magic != NBD_REQUEST_MAGIC) {
- error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
+ if (magic != expect) {
+ error_setg(errp, "invalid magic (got 0x%" PRIx32 ", expected 0x%"
+ PRIx32 ")", magic, expect);
return -EINVAL;
}
return 0;
--
2.41.0
- [PATCH v7 01/12] nbd/server: Support a request payload, (continued)
[PATCH v7 06/12] nbd/client: Plumb errp through nbd_receive_replies, Eric Blake, 2023/09/25
[PATCH v7 07/12] nbd/client: Initial support for extended headers, Eric Blake, 2023/09/25
[PATCH v7 02/12] nbd/server: Prepare to receive extended header requests,
Eric Blake <=
[PATCH v7 04/12] nbd/server: Support 64-bit block status, Eric Blake, 2023/09/25
[PATCH v7 05/12] nbd/server: Enable initial support for extended headers, Eric Blake, 2023/09/25
[PATCH v7 03/12] nbd/server: Prepare to send extended header replies, Eric Blake, 2023/09/25
[PATCH v7 11/12] nbd/server: Prepare for per-request filtering of BLOCK_STATUS, Eric Blake, 2023/09/25
[PATCH v7 08/12] nbd/client: Accept 64-bit block status chunks, Eric Blake, 2023/09/25
[PATCH v7 10/12] nbd/server: Refactor list of negotiated meta contexts, Eric Blake, 2023/09/25
[PATCH v7 12/12] nbd/server: Add FLAG_PAYLOAD support to CMD_BLOCK_STATUS, Eric Blake, 2023/09/25
[PATCH v7 09/12] nbd/client: Request extended headers during negotiation, Eric Blake, 2023/09/25