From: ChenXiaoSong <chenxiaosong@kylinos.cn>
Date: Sun, 28 Jun 2026 07:42:43 +0000 (+0000)
Subject: smb/server: do not require delete access for non-replacing links
X-Git-Tag: v7.2-rc2~9^2~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=851ed9e09639e0daf79a506ce26097b296ed5518;p=thirdparty%2Fkernel%2Flinux.git

smb/server: do not require delete access for non-replacing links

Reproducer:

  1. server: systemctl start ksmbd
  2. client: mount -t cifs //${server_ip}/export /mnt
  3. client: touch /mnt/file; ln /mnt/file /mnt/hardlink
  4. client err log: ln: failed to create hard link 'hardlink' =>
     'file': Permission denied
  5. server err log: ksmbd: no right to delete : 0x80

Fixes: 13f3942f2bf4 ("ksmbd: add per-handle permission check to FILE_LINK_INFORMATION")
Cc: stable@vger.kernel.org
Reported-by: Steve French <stfrench@microsoft.com>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
---

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 727ba86ede36..097f51fc7ed6 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -6921,16 +6921,18 @@ static int smb2_set_info_file(struct ksmbd_work *work, struct ksmbd_file *fp,
 	}
 	case FILE_LINK_INFORMATION:
 	{
-		if (!(fp->daccess & FILE_DELETE_LE)) {
-			pr_err("no right to delete : 0x%x\n", fp->daccess);
-			return -EACCES;
-		}
+		struct smb2_file_link_info *file_info;
 
 		if (buf_len < sizeof(struct smb2_file_link_info))
 			return -EMSGSIZE;
 
-		return smb2_create_link(work, work->tcon->share_conf,
-					(struct smb2_file_link_info *)buffer,
+		file_info = (struct smb2_file_link_info *)buffer;
+		if (file_info->ReplaceIfExists && !(fp->daccess & FILE_DELETE_LE)) {
+			pr_err("no right to delete : 0x%x\n", fp->daccess);
+			return -EACCES;
+		}
+
+		return smb2_create_link(work, work->tcon->share_conf, file_info,
 					buf_len, fp->filp,
 					work->conn->local_nls);
 	}