From: Nicholas Bellinger nab@linux-iscsi.org
commit 21aaa23b0ebbd19334fa461370c03cbb076b3295 upstream.
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 --- drivers/target/iscsi/iscsi_target.c | 2 +- drivers/target/target_core_tpg.c | 44 ++++++++++++++++++++++++++++++++-- drivers/target/target_core_transport.c | 18 +++++++++----- include/target/target_core_fabric.h | 2 ++ 4 files changed, 57 insertions(+), 9 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 7444640a..d6cb9e8 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -3449,7 +3449,7 @@ 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 47f0644..6c350f0 100644 --- a/drivers/target/target_core_tpg.c +++ b/drivers/target/target_core_tpg.c @@ -110,9 +110,21 @@ 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. + */ spin_lock_irq(&tpg->acl_node_lock); acl = __core_tpg_get_initiator_node_acl(tpg, initiatorname); + if (acl) { + if (!kref_get_unless_zero(&acl->acl_kref)) + acl = NULL; + } spin_unlock_irq(&tpg->acl_node_lock);
return acl; @@ -254,6 +266,25 @@ static int core_create_device_list_for_node(struct se_node_acl *nacl) return 0; }
+bool target_tpg_has_node_acl(struct se_portal_group *tpg, + const char *initiatorname) +{ + struct se_node_acl *acl; + bool found = false; + + spin_lock_irq(&tpg->acl_node_lock); + list_for_each_entry(acl, &tpg->acl_node_list, acl_list) { + if (!strcmp(acl->initiatorname, initiatorname)) { + found = true; + break; + } + } + spin_unlock_irq(&tpg->acl_node_lock); + + return found; +} +EXPORT_SYMBOL(target_tpg_has_node_acl); + /* core_tpg_check_initiator_node_acl() * * @@ -274,10 +305,19 @@ struct se_node_acl *core_tpg_check_initiator_node_acl( acl = tpg->se_tpg_tfo->tpg_alloc_fabric_acl(tpg); 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_init(&acl->acl_kref); + kref_get(&acl->acl_kref);
INIT_LIST_HEAD(&acl->acl_list); INIT_LIST_HEAD(&acl->acl_sess_list); - kref_init(&acl->acl_kref); init_completion(&acl->acl_free_comp); spin_lock_init(&acl->device_list_lock); spin_lock_init(&acl->nacl_sess_lock); diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index b7d27b8..3bf46bf 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -359,7 +359,6 @@ 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); /* @@ -456,6 +455,7 @@ 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) { @@ -488,6 +488,15 @@ 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); if (is_vmalloc_addr(se_sess->sess_cmd_map)) @@ -505,7 +514,6 @@ 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;
if (!se_tpg) { transport_free_session(se_sess); @@ -533,9 +541,9 @@ void transport_deregister_session(struct se_session *se_sess) spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags); 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; se_tfo->tpg_release_fabric_acl(se_tpg, se_nacl);
- comp_nacl = false; spin_lock_irqsave(&se_tpg->acl_node_lock, flags); } } @@ -546,10 +554,8 @@ void transport_deregister_session(struct se_session *se_sess) /* * 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); } diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h index 24c8d9d..419a8c8 100644 --- a/include/target/target_core_fabric.h +++ b/include/target/target_core_fabric.h @@ -171,6 +171,8 @@ int transport_lookup_tmr_lun(struct se_cmd *, u32);
struct se_node_acl *core_tpg_get_initiator_node_acl(struct se_portal_group *tpg, unsigned char *); +bool target_tpg_has_node_acl(struct se_portal_group *tpg, + const char *); struct se_node_acl *core_tpg_check_initiator_node_acl(struct se_portal_group *, unsigned char *); void core_tpg_clear_object_luns(struct se_portal_group *);