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authorNicholas Bellinger <nab@linux-iscsi.org>2016-01-07 22:09:27 -0800
committerNicholas Bellinger <nab@linux-iscsi.org>2016-01-20 01:34:15 -0800
commit21aaa23b0ebbd19334fa461370c03cbb076b3295 (patch)
treeee480a095123426c81a9aac8fed0fba8fe27fc74 /drivers/target/target_core_tpg.c
parentd36ad77f702356afb1009d2987b0ab55da4c7d57 (diff)
target: Obtain se_node_acl->acl_kref during get_initiator_node_acl
This patch addresses a long standing race where obtaining se_node_acl->acl_kref in __transport_register_session() happens a bit too late, and leaves open the potential for core_tpg_del_initiator_node_acl() to hit a NULL pointer dereference. Instead, take ->acl_kref in core_tpg_get_initiator_node_acl() while se_portal_group->acl_node_mutex is held, and move the final target_put_nacl() from transport_deregister_session() into transport_free_session() so that fabric driver login failure handling using the modern method to still work as expected. Also, update core_tpg_get_initiator_node_acl() to take an extra reference for dynamically generated acls for demo-mode, before returning to fabric caller. Also update iscsi-target sendtargets special case handling to use target_tpg_has_node_acl() when checking if demo_mode_discovery == true during discovery lookup. Note the existing wait_for_completion(&acl->acl_free_comp) in core_tpg_del_initiator_node_acl() does not change. Cc: Sagi Grimberg <sagig@mellanox.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Andy Grover <agrover@redhat.com> Cc: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target/target_core_tpg.c')
-rw-r--r--drivers/target/target_core_tpg.c42
1 files changed, 41 insertions, 1 deletions
diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 67be44da29ff..3608b1b5ecf7 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -75,9 +75,21 @@ struct se_node_acl *core_tpg_get_initiator_node_acl(
unsigned char *initiatorname)
{
struct se_node_acl *acl;
-
+ /*
+ * Obtain se_node_acl->acl_kref using fabric driver provided
+ * initiatorname[] during node acl endpoint lookup driven by
+ * new se_session login.
+ *
+ * The reference is held until se_session shutdown -> release
+ * occurs via fabric driver invoked transport_deregister_session()
+ * or transport_free_session() code.
+ */
mutex_lock(&tpg->acl_node_mutex);
acl = __core_tpg_get_initiator_node_acl(tpg, initiatorname);
+ if (acl) {
+ if (!kref_get_unless_zero(&acl->acl_kref))
+ acl = NULL;
+ }
mutex_unlock(&tpg->acl_node_mutex);
return acl;
@@ -224,6 +236,25 @@ static void target_add_node_acl(struct se_node_acl *acl)
acl->initiatorname);
}
+bool target_tpg_has_node_acl(struct se_portal_group *tpg,
+ const char *initiatorname)
+{
+ struct se_node_acl *acl;
+ bool found = false;
+
+ mutex_lock(&tpg->acl_node_mutex);
+ list_for_each_entry(acl, &tpg->acl_node_list, acl_list) {
+ if (!strcmp(acl->initiatorname, initiatorname)) {
+ found = true;
+ break;
+ }
+ }
+ mutex_unlock(&tpg->acl_node_mutex);
+
+ return found;
+}
+EXPORT_SYMBOL(target_tpg_has_node_acl);
+
struct se_node_acl *core_tpg_check_initiator_node_acl(
struct se_portal_group *tpg,
unsigned char *initiatorname)
@@ -240,6 +271,15 @@ struct se_node_acl *core_tpg_check_initiator_node_acl(
acl = target_alloc_node_acl(tpg, initiatorname);
if (!acl)
return NULL;
+ /*
+ * When allocating a dynamically generated node_acl, go ahead
+ * and take the extra kref now before returning to the fabric
+ * driver caller.
+ *
+ * Note this reference will be released at session shutdown
+ * time within transport_free_session() code.
+ */
+ kref_get(&acl->acl_kref);
acl->dynamic_node_acl = 1;
/*