[PATCH 6.6 067/299] smb: client: increase number of PDUs allowed in a compound request

Greg Kroah-Hartman
2024-02-27T13:51:02Z

From: Paulo Alcantara <pc@manguebit.com>

[ Upstream commit 11d4d1dba3315f73d2d1d386f5bf4811a8241d45 ]

With the introduction of SMB2_OP_QUERY_WSL_EA, the client may now send
5 commands in a single compound request in order to query xattrs from
potential WSL reparse points, which should be fine as we currently
allow up to 5 PDUs in a single compound request. However, if
encryption is enabled (e.g. 'seal' mount option) or enforced by the
server, current MAX_COMPOUND(5) won't be enough as we require an extra
PDU for the transform header.

Fix this by increasing MAX_COMPOUND to 7 and, while we're at it, add
an WARN_ON_ONCE() and return -EIO instead of -ENOMEM in case we
attempt to send a compound request that couldn't include the extra
transform header.

Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/smb/client/cifsglob.h | 2 +-
fs/smb/client/transport.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index dcc41fe33b705..462554917e5a1 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -82,7 +82,7 @@
#define SMB_INTERFACE_POLL_INTERVAL 600

/* maximum number of PDUs in one compound */
-#define MAX_COMPOUND 5
+#define MAX_COMPOUND 7

/*
* Default number of credits to keep available for SMB3.
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index e00278fcfa4fa..994d701934329 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -435,8 +435,8 @@ smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
if (!(flags & CIFS_TRANSFORM_REQ))
return __smb_send_rqst(server, num_rqst, rqst);

- if (num_rqst > MAX_COMPOUND - 1)
- return -ENOMEM;
+ if (WARN_ON_ONCE(num_rqst > MAX_COMPOUND - 1))
+ return -EIO;

if (!server->ops->init_transform_rq) {
cifs_server_dbg(VFS, "Encryption requested but transform callback is missing\n");
--
2.43.0