From 388e4139db27a9e3612c9d356b826f5b1ff6a9e3 Mon Sep 17 00:00:00 2001 From: Gil Portnoy Date: Fri, 12 Jun 2026 07:15:38 +0900 Subject: [PATCH] ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE The FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the destination file's data via vfs_clone_file_range() with neither the share-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle fp->daccess check that the other write-bearing arms carry. A client can overwrite destination data on a read-only share, or from a handle opened with only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp). FILE_WRITE_ATTRIBUTES-only destination handle overwrote the file's data via the clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix; require FILE_WRITE_DATA since this writes data. Cc: stable@vger.kernel.org Signed-off-by: Gil Portnoy Acked-by: Namjae Jeon Signed-off-by: Steve French --- fs/smb/server/smb2pdu.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 4e00879317959..32f568cea16a9 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -8766,6 +8766,17 @@ int smb2_ioctl(struct ksmbd_work *work) goto dup_ext_out; } + if (!test_tree_conn_flag(work->tcon, + KSMBD_TREE_CONN_FLAG_WRITABLE)) { + ret = -EACCES; + goto dup_ext_out; + } + + if (!(fp_out->daccess & FILE_WRITE_DATA_LE)) { + ret = -EACCES; + goto dup_ext_out; + } + src_off = le64_to_cpu(dup_ext->SourceFileOffset); dst_off = le64_to_cpu(dup_ext->TargetFileOffset); length = le64_to_cpu(dup_ext->ByteCount); -- 2.53.0