cifsd: lookup a file with LOOKUP_FOLLOW only if 'follow symlinks = yes'

Some vfs help functions lookup a file with
LOOKUP_FOLLOW regardless of the "follow symlinks"
option.
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifsd/smb2pdu.c

@@ -4583,8 +4583,12 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 	struct path path;
 	int rc = 0, len;
 	int fs_infoclass_size = 0;
+	int lookup_flags = 0;
 
-	rc = ksmbd_vfs_kern_path(share->path, LOOKUP_FOLLOW, &path, 0);
+	if (test_share_config_flag(share, KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
+		lookup_flags = LOOKUP_FOLLOW;
+
+	rc = ksmbd_vfs_kern_path(share->path, lookup_flags, &path, 0);
 	if (rc) {
 		ksmbd_err("cannot create vfs path\n");
 		return -EIO;

fs/cifsd/vfs.c

@@ -572,11 +572,16 @@ int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name)
 	struct path path;
 	struct dentry *dentry, *parent;
 	int err;
+	int flags = 0;
 
 	if (ksmbd_override_fsids(work))
 		return -ENOMEM;
 
-	err = kern_path(name, LOOKUP_FOLLOW, &path);
+	if (test_share_config_flag(work->tcon->share_conf,
+				   KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
+		flags = LOOKUP_FOLLOW;
+
+	err = kern_path(name, flags, &path);
 	if (err) {
 		ksmbd_debug(VFS, "can't get %s, err %d\n", name, err);
 		ksmbd_revert_fsids(work);
@@ -634,11 +639,16 @@ int ksmbd_vfs_link(struct ksmbd_work *work, const char *oldname,
 	struct path oldpath, newpath;
 	struct dentry *dentry;
 	int err;
+	int flags = 0;
 
 	if (ksmbd_override_fsids(work))
 		return -ENOMEM;
 
-	err = kern_path(oldname, LOOKUP_FOLLOW, &oldpath);
+	if (test_share_config_flag(work->tcon->share_conf,
+				   KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
+		flags = LOOKUP_FOLLOW;
+
+	err = kern_path(oldname, flags, &oldpath);
 	if (err) {
 		ksmbd_err("cannot get linux path for %s, err = %d\n",
 			  oldname, err);
@@ -646,7 +656,7 @@ int ksmbd_vfs_link(struct ksmbd_work *work, const char *oldname,
 	}
 
 	dentry = kern_path_create(AT_FDCWD, newname, &newpath,
-				  LOOKUP_FOLLOW | LOOKUP_REVAL);
+				  flags | LOOKUP_REVAL);
 	if (IS_ERR(dentry)) {
 		err = PTR_ERR(dentry);
 		ksmbd_err("path create err for %s, err %d\n", newname, err);
@@ -749,6 +759,7 @@ int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
 	struct dentry *src_dent, *trap_dent, *src_child;
 	char *dst_name;
 	int err;
+	int flags;
 
 	dst_name = extract_last_component(newname);
 	if (!dst_name)
@@ -757,7 +768,12 @@ int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
 	src_dent_parent = dget_parent(fp->filp->f_path.dentry);
 	src_dent = fp->filp->f_path.dentry;
 
-	err = kern_path(newname, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &dst_path);
+	flags = LOOKUP_DIRECTORY;
+	if (test_share_config_flag(work->tcon->share_conf,
+				   KSMBD_SHARE_FLAG_FOLLOW_SYMLINKS))
+		flags |= LOOKUP_FOLLOW;
+
+	err = kern_path(newname, flags, &dst_path);
 	if (err) {
 		ksmbd_debug(VFS, "Cannot get path for %s [%d]\n", newname, err);
 		goto out;