linux-kernel - [PATCH] cifs: Implement is_network_name

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Message-Id: <20241222171431.24657-1-pali@kernel.org>
Date: Sun, 22 Dec 2024 18:14:31 +0100
From: Pali Rohár <pali@...nel.org>
To: Steve French <sfrench@...ba.org>,
	Paulo Alcantara <pc@...guebit.com>,
	Ronnie Sahlberg <ronniesahlberg@...il.com>
Cc: linux-cifs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] cifs: Implement is_network_name_deleted for SMB1

This change allows Linux SMB1 client to autoreconnect the share when it is
modified on server by admin operation which removes and re-adds it.

Implementation is reused from SMB2+ is_network_name_deleted callback. There
are just adjusted checks for error codes and access to struct smb_hdr.

Signed-off-by: Pali Rohár <pali@...nel.org>
---
 fs/smb/client/smb1ops.c | 44 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
index 0533aca770fc..76e7353f2a72 100644
--- a/fs/smb/client/smb1ops.c
+++ b/fs/smb/client/smb1ops.c
@@ -14,6 +14,8 @@
 #include "cifspdu.h"
 #include "cifs_unicode.h"
 #include "fs_context.h"
+#include "nterr.h"
+#include "smberr.h"
 
 /*
  * An NT cancel request header looks just like the original request except:
@@ -1075,6 +1077,47 @@ cifs_make_node(unsigned int xid, struct inode *inode,
 				  full_path, mode, dev);
 }
 
+static bool
+cifs_is_network_name_deleted(char *buf, struct TCP_Server_Info *server)
+{
+	struct smb_hdr *shdr = (struct smb_hdr *)buf;
+	struct TCP_Server_Info *pserver;
+	struct cifs_ses *ses;
+	struct cifs_tcon *tcon;
+
+	if (shdr->Flags2 & SMBFLG2_ERR_STATUS) {
+		if (shdr->Status.CifsError != cpu_to_le32(NT_STATUS_NETWORK_NAME_DELETED))
+			return false;
+	} else {
+		if (shdr->Status.DosError.ErrorClass != ERRSRV ||
+		    shdr->Status.DosError.Error != cpu_to_le16(ERRinvtid))
+			return false;
+	}
+
+	/* If server is a channel, select the primary channel */
+	pserver = SERVER_IS_CHAN(server) ? server->primary_server : server;
+
+	spin_lock(&cifs_tcp_ses_lock);
+	list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
+		if (cifs_ses_exiting(ses))
+			continue;
+		list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
+			if (tcon->tid == le32_to_cpu(shdr->Tid)) {
+				spin_lock(&tcon->tc_lock);
+				tcon->need_reconnect = true;
+				spin_unlock(&tcon->tc_lock);
+				spin_unlock(&cifs_tcp_ses_lock);
+				pr_warn_once("Server share %s deleted.\n",
+					     tcon->tree_name);
+				return true;
+			}
+		}
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
+
+	return false;
+}
+
 struct smb_version_operations smb1_operations = {
 	.send_cancel = send_nt_cancel,
 	.compare_fids = cifs_compare_fids,
@@ -1159,6 +1202,7 @@ struct smb_version_operations smb1_operations = {
 	.get_acl_by_fid = get_cifs_acl_by_fid,
 	.set_acl = set_cifs_acl,
 	.make_node = cifs_make_node,
+	.is_network_name_deleted = cifs_is_network_name_deleted,
 };
 
 struct smb_version_values smb1_values = {
-- 
2.20.1