From cedff600f1642aa982178503552f0d007bc829c8 Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Sat, 13 Jun 2026 22:00:02 +0900 Subject: [PATCH] ksmbd: require source read access for duplicate extents FSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to vfs_clone_file_range() or vfs_copy_file_range() without checking the SMB access mask granted to the source handle. A handle opened with attribute access can consequently be used to copy file contents into an attacker-readable destination. Require FILE_READ_DATA on the source handle before either VFS operation, matching other ksmbd data-copy paths. Cc: stable@vger.kernel.org Reported-by: Musaab Khan Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- fs/smb/server/smb2pdu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 6d3f975d582f4..fcb1bcd5de95d 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -8778,6 +8778,10 @@ int smb2_ioctl(struct ksmbd_work *work) ret = -EACCES; goto dup_ext_out; } + if (!(fp_in->daccess & FILE_READ_DATA_LE)) { + ret = -EACCES; + goto dup_ext_out; + } src_off = le64_to_cpu(dup_ext->SourceFileOffset); dst_off = le64_to_cpu(dup_ext->TargetFileOffset); -- 2.47.3