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authorNicholas Bellinger <nab@linux-iscsi.org>2016-01-08 09:09:27 +0300
committerNicholas Bellinger <nab@linux-iscsi.org>2016-01-20 12:34:15 +0300
commit21aaa23b0ebbd19334fa461370c03cbb076b3295 (patch)
treeee480a095123426c81a9aac8fed0fba8fe27fc74 /drivers/target
parentd36ad77f702356afb1009d2987b0ab55da4c7d57 (diff)
downloadlinux-21aaa23b0ebbd19334fa461370c03cbb076b3295.tar.xz
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')
-rw-r--r--drivers/target/iscsi/iscsi_target.c2
-rw-r--r--drivers/target/target_core_tpg.c42
-rw-r--r--drivers/target/target_core_transport.c19
3 files changed, 55 insertions, 8 deletions
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index a81c0e5ca293..762b2d6ea1cc 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -3435,7 +3435,7 @@ iscsit_build_sendtargets_response(struct iscsi_cmd *cmd,
if ((tpg->tpg_attrib.generate_node_acls == 0) &&
(tpg->tpg_attrib.demo_mode_discovery == 0) &&
- (!core_tpg_get_initiator_node_acl(&tpg->tpg_se_tpg,
+ (!target_tpg_has_node_acl(&tpg->tpg_se_tpg,
cmd->conn->sess->sess_ops->InitiatorName))) {
continue;
}
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;
/*
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 7b05ebf8053c..a7c1bb54cf72 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -341,7 +341,6 @@ void __transport_register_session(
&buf[0], PR_REG_ISID_LEN);
se_sess->sess_bin_isid = get_unaligned_be64(&buf[0]);
}
- kref_get(&se_nacl->acl_kref);
spin_lock_irq(&se_nacl->nacl_sess_lock);
/*
@@ -432,6 +431,7 @@ void target_put_nacl(struct se_node_acl *nacl)
{
kref_put(&nacl->acl_kref, target_complete_nacl);
}
+EXPORT_SYMBOL(target_put_nacl);
void transport_deregister_session_configfs(struct se_session *se_sess)
{
@@ -464,6 +464,15 @@ EXPORT_SYMBOL(transport_deregister_session_configfs);
void transport_free_session(struct se_session *se_sess)
{
+ struct se_node_acl *se_nacl = se_sess->se_node_acl;
+ /*
+ * Drop the se_node_acl->nacl_kref obtained from within
+ * core_tpg_get_initiator_node_acl().
+ */
+ if (se_nacl) {
+ se_sess->se_node_acl = NULL;
+ target_put_nacl(se_nacl);
+ }
if (se_sess->sess_cmd_map) {
percpu_ida_destroy(&se_sess->sess_tag_pool);
kvfree(se_sess->sess_cmd_map);
@@ -478,7 +487,7 @@ void transport_deregister_session(struct se_session *se_sess)
const struct target_core_fabric_ops *se_tfo;
struct se_node_acl *se_nacl;
unsigned long flags;
- bool comp_nacl = true, drop_nacl = false;
+ bool drop_nacl = false;
if (!se_tpg) {
transport_free_session(se_sess);
@@ -510,18 +519,16 @@ void transport_deregister_session(struct se_session *se_sess)
if (drop_nacl) {
core_tpg_wait_for_nacl_pr_ref(se_nacl);
core_free_device_list_for_node(se_nacl, se_tpg);
+ se_sess->se_node_acl = NULL;
kfree(se_nacl);
- comp_nacl = false;
}
pr_debug("TARGET_CORE[%s]: Deregistered fabric_sess\n",
se_tpg->se_tpg_tfo->get_fabric_name());
/*
* If last kref is dropping now for an explicit NodeACL, awake sleeping
* ->acl_free_comp caller to wakeup configfs se_node_acl->acl_group
- * removal context.
+ * removal context from within transport_free_session() code.
*/
- if (se_nacl && comp_nacl)
- target_put_nacl(se_nacl);
transport_free_session(se_sess);
}