[PATCH] ksmbd: accept unspecified volatile ID on durable reconnect

[Namjae Jeon <linkinjeon@kernel.org>]

BVT_DurableHandleV1_Reconnect_WithBatchOplock,
BVT_DurableHandleV1_Reconnect_WithLeaseV1,
BVT_DurableHandleV2_Reconnect_WithBatchOplock, and
BVT_DurableHandleV2_Reconnect_WithLeaseV1 fail to reconnect a durable
handle when the request leaves VolatileFileId unset.

A durable reconnect request may omit VolatileFileId by setting it to
zero. Treating zero as an ID makes ksmbd reject the request whenever the
saved volatile ID is nonzero.

Only compare the saved and requested volatile IDs when the request
contains a nonzero value. Explicit mismatches continue to be rejected.

This allows SMB2 durable handle V1 and V2 reconnects that identify the
handle through the persistent ID and reconnect context.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/smb2pdu.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index bfa895414fd4..bd806dca9dcd 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -3584,7 +3584,9 @@ static int parse_durable_handle_context(struct ksmbd_work *work,
 				goto out;
 			}
 
-			if (dh_info->fp->durable_volatile_id !=
+			/* A zero VolatileFileId means that the client did not specify it. */
+			if (recon_v2->dcontext.Fid.VolatileFileId &&
+			    dh_info->fp->durable_volatile_id !=
 			    recon_v2->dcontext.Fid.VolatileFileId) {
 				err = -EBADF;
 				ksmbd_put_durable_fd(dh_info->fp);
@@ -3637,7 +3639,9 @@ static int parse_durable_handle_context(struct ksmbd_work *work,
 				goto out;
 			}
 
-			if (dh_info->fp->durable_volatile_id !=
+			/* A zero VolatileFileId means that the client did not specify it. */
+			if (recon->Data.Fid.VolatileFileId &&
+			    dh_info->fp->durable_volatile_id !=
 			    recon->Data.Fid.VolatileFileId) {
 				err = -EBADF;
 				ksmbd_put_durable_fd(dh_info->fp);
-- 
2.25.1