[PATCH 3/3] ksmbd: move leading slash check to smb2_get_name()

[Namjae Jeon <linkinjeon@kernel.org>]

If the directory name in the root of the share starts with
character like 镜(0x955c) or Ṝ(0x1e5c), it (and anything inside)
cannot be accessed. The leading slash check must be checked after
converting unicode to nls string.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/smb2pdu.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 4fb5070d3dc5..8bcede718c21 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -630,6 +630,12 @@ smb2_get_name(const char *src, const int maxlen, struct nls_table *local_nls)
 		return name;
 	}
 
+	if (*name == '\\') {
+		pr_err("not allow directory name included leading slash\n");
+		kfree(name);
+		return ERR_PTR(-EINVAL);
+	}
+
 	ksmbd_conv_path_to_unix(name);
 	ksmbd_strip_last_slash(name);
 	return name;
@@ -2842,20 +2848,11 @@ int smb2_open(struct ksmbd_work *work)
 	}
 
 	if (req->NameLength) {
-		if ((req->CreateOptions & FILE_DIRECTORY_FILE_LE) &&
-		    *(char *)req->Buffer == '\\') {
-			pr_err("not allow directory name included leading slash\n");
-			rc = -EINVAL;
-			goto err_out2;
-		}
-
 		name = smb2_get_name((char *)req + le16_to_cpu(req->NameOffset),
 				     le16_to_cpu(req->NameLength),
 				     work->conn->local_nls);
 		if (IS_ERR(name)) {
 			rc = PTR_ERR(name);
-			if (rc != -ENOMEM)
-				rc = -ENOENT;
 			name = NULL;
 			goto err_out2;
 		}
-- 
2.25.1