target: Add link_magic for fabric allow_link destination target_items

This patch adds [dev,lun]_link_magic value assignment + checks within generic
target_fabric_port_link() and target_fabric_mappedlun_link() code to ensure
destination config_item *target_item sent from configfs_symlink() ->
config_item_operations->allow_link() is the underlying se_device->dev_group
and se_lun->lun_group that we expect to symlink.

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 645d90ac6097..1346ee04db5e 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -624,6 +624,8 @@ struct se_dev_stat_grps {
 };
 
 struct se_device {
+#define SE_DEV_LINK_MAGIC                       0xfeeddeef
+        u32                     dev_link_magic;
         /* RELATIVE TARGET PORT IDENTIFER Counter */
         u16                     dev_rpti_counter;
         /* Used for SAM Task Attribute ordering */
@@ -722,6 +724,8 @@ struct se_port_stat_grps {
 };
 
 struct se_lun {
+#define SE_LUN_LINK_MAGIC                       0xffff7771
+        u32                     lun_link_magic;
         /* See transport_lun_status_table */
         enum transport_lun_status_table lun_status;
         u32                     lun_access;