ksmbd: set unique value to volume serial field in FS_VOLUME_INFORMATION

Steve French reported ksmbd set fixed value to volume serial field in
FS_VOLUME_INFORMATION. Volume serial value needs to be set to a unique
value for client fscache. This patch set crc value that is generated
with share name, path name and netbios name to volume serial.

Fixes: e2f34481 ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org # v5.15
Reported-by: Steve French <smfrench@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/Kconfig

@@ -19,6 +19,7 @@ config SMB_SERVER
 	select CRYPTO_GCM
 	select ASN1
 	select OID_REGISTRY
+	select CRC32
 	default n
 	help
 	  Choose Y here if you want to allow SMB3 compliant clients

fs/ksmbd/server.c

@@ -632,5 +632,6 @@ MODULE_SOFTDEP("pre: sha512");
 MODULE_SOFTDEP("pre: aead2");
 MODULE_SOFTDEP("pre: ccm");
 MODULE_SOFTDEP("pre: gcm");
+MODULE_SOFTDEP("pre: crc32");
 module_init(ksmbd_server_init)
 module_exit(ksmbd_server_exit)

fs/ksmbd/smb2pdu.c

@@ -4892,11 +4892,18 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 	{
 		struct filesystem_vol_info *info;
 		size_t sz;
+		unsigned int serial_crc = 0;
 
 		info = (struct filesystem_vol_info *)(rsp->Buffer);
 		info->VolumeCreationTime = 0;
+		serial_crc = crc32_le(serial_crc, share->name,
+				      strlen(share->name));
+		serial_crc = crc32_le(serial_crc, share->path,
+				      strlen(share->path));
+		serial_crc = crc32_le(serial_crc, ksmbd_netbios_name(),
+				      strlen(ksmbd_netbios_name()));
 		/* Taking dummy value of serial number*/
-		info->SerialNumber = cpu_to_le32(0xbc3ac512);
+		info->SerialNumber = cpu_to_le32(serial_crc);
 		len = smbConvertToUTF16((__le16 *)info->VolumeLabel,
 					share->name, PATH_MAX,
 					conn->local_nls, 0);