From 21aaa23b0ebbd19334fa461370c03cbb076b3295 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Thu, 7 Jan 2016 22:09:27 -0800 Subject: 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 Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Andy Grover Cc: Mike Christie Signed-off-by: Nicholas Bellinger diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index a81c0e5..762b2d6 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 67be44d..3608b1b 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 7b05ebf..a7c1bb5 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); } diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h index 48e002f..5665340 100644 --- a/include/target/target_core_fabric.h +++ b/include/target/target_core_fabric.h @@ -169,6 +169,8 @@ void core_allocate_nexus_loss_ua(struct se_node_acl *acl); 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 *); int core_tpg_set_initiator_node_queue_depth(struct se_node_acl *, u32); -- cgit v0.10.2