[PATCH 4/4] mka: implement reference counting on data_key

[Sabrina Dubroca]

struct data_key already had a `user` field for reference counting, but
it was basically unused.

Add a ieee802_1x_kay_use_data_key() function to take a reference on a
key, and use ieee802_1x_kay_deinit_data_key() to release the reference.

Signed-off-by: Sabrina Dubroca <sd at queasysnail.net>
---
 src/pae/ieee802_1x_kay.c | 26 ++++++++++++++++++++++----
 src/pae/ieee802_1x_kay.h |  2 +-
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/src/pae/ieee802_1x_kay.c b/src/pae/ieee802_1x_kay.c
index d09f26664413..25f7f2fee827 100644
--- a/src/pae/ieee802_1x_kay.c
+++ b/src/pae/ieee802_1x_kay.c
@@ -411,6 +411,8 @@ ieee802_1x_kay_get_peer_sci(struct ieee802_1x_mka_participant *participant,
 }
 
 
+static void ieee802_1x_kay_use_data_key(struct data_key *pkey);
+
 /**
  * ieee802_1x_kay_init_receive_sa -
  */
@@ -429,6 +431,7 @@ ieee802_1x_kay_init_receive_sa(struct receive_sc *psc, u8 an, u32 lowest_pn,
 		return NULL;
 	}
 
+	ieee802_1x_kay_use_data_key(key);
 	psa->pkey = key;
 	psa->lowest_pn = lowest_pn;
 	psa->next_pn = lowest_pn;
@@ -447,11 +450,13 @@ ieee802_1x_kay_init_receive_sa(struct receive_sc *psc, u8 an, u32 lowest_pn,
 }
 
 
+static void ieee802_1x_kay_deinit_data_key(struct data_key *pkey);
 /**
  * ieee802_1x_kay_deinit_receive_sa -
  */
 static void ieee802_1x_kay_deinit_receive_sa(struct receive_sa *psa)
 {
+	ieee802_1x_kay_deinit_data_key(psa->pkey);
 	psa->pkey = NULL;
 	wpa_printf(MSG_DEBUG,
 		   "KaY: Delete receive SA(an: %hhu) of SC",
@@ -1609,6 +1614,7 @@ ieee802_1x_mka_decode_dist_sak_body(
 	sa_key->an = body->dan;
 	ieee802_1x_kay_init_data_key(sa_key);
 
+	ieee802_1x_kay_use_data_key(sa_key);
 	dl_list_add(&participant->sak_list, &sa_key->list);
 
 	ieee802_1x_cp_set_ciphersuite(kay->cp, cs->id);
@@ -1870,7 +1876,16 @@ static struct mka_param_body_handler mka_body_handler[] = {
 
 
 /**
- * ieee802_1x_kay_deinit_data_key -
+ * ieee802_1x_kay_use_data_key - take reference on a key
+ */
+static void ieee802_1x_kay_use_data_key(struct data_key *pkey)
+{
+	pkey->user++;
+}
+
+/**
+ * ieee802_1x_kay_deinit_data_key - release reference on a key
+ * free if there are no remaining users
  */
 static void ieee802_1x_kay_deinit_data_key(struct data_key *pkey)
 {
@@ -1881,7 +1896,6 @@ static void ieee802_1x_kay_deinit_data_key(struct data_key *pkey)
 	if (pkey->user > 1)
 		return;
 
-	dl_list_del(&pkey->list);
 	os_free(pkey->key);
 	os_free(pkey);
 }
@@ -1991,7 +2005,9 @@ ieee802_1x_kay_generate_new_sak(struct ieee802_1x_mka_participant *participant)
 
 	participant->new_key = sa_key;
 
+	ieee802_1x_kay_use_data_key(sa_key);
 	dl_list_add(&participant->sak_list, &sa_key->list);
+
 	ieee802_1x_cp_set_ciphersuite(kay->cp, cs->id);
 	ieee802_1x_cp_sm_step(kay->cp);
 	ieee802_1x_cp_set_offset(kay->cp, kay->macsec_confidentiality);
@@ -2431,6 +2447,7 @@ ieee802_1x_kay_init_transmit_sa(struct transmit_sc *psc, u8 an, u32 next_PN,
 		psa->confidentiality = FALSE;
 
 	psa->an = an;
+	ieee802_1x_kay_use_data_key(key);
 	psa->pkey = key;
 	psa->next_pn = next_PN;
 	psa->sc = psc;
@@ -2452,6 +2469,7 @@ ieee802_1x_kay_init_transmit_sa(struct transmit_sc *psc, u8 an, u32 next_PN,
  */
 static void ieee802_1x_kay_deinit_transmit_sa(struct transmit_sa *psa)
 {
+	ieee802_1x_kay_deinit_data_key(psa->pkey);
 	psa->pkey = NULL;
 	wpa_printf(MSG_DEBUG,
 		   "KaY: Delete transmit SA(an: %hhu) of SC",
@@ -2700,6 +2718,7 @@ int ieee802_1x_kay_delete_sas(struct ieee802_1x_kay *kay,
 	dl_list_for_each_safe(sa_key, pre_key, &principal->sak_list,
 			      struct data_key, list) {
 		if (is_ki_equal(&sa_key->key_identifier, ki)) {
+			dl_list_del(&sa_key->list);
 			ieee802_1x_kay_deinit_data_key(sa_key);
 			break;
 		}
@@ -3367,8 +3386,7 @@ ieee802_1x_kay_delete_mka(struct ieee802_1x_kay *kay, struct mka_key_name *ckn)
 		sak = dl_list_entry(participant->sak_list.next,
 				    struct data_key, list);
 		dl_list_del(&sak->list);
-		os_free(sak->key);
-		os_free(sak);
+		ieee802_1x_kay_deinit_data_key(sak);
 	}
 	while (!dl_list_empty(&participant->rxsc_list)) {
 		rxsc = dl_list_entry(participant->rxsc_list.next,
diff --git a/src/pae/ieee802_1x_kay.h b/src/pae/ieee802_1x_kay.h
index 5233cb216ada..576a8a085709 100644
--- a/src/pae/ieee802_1x_kay.h
+++ b/src/pae/ieee802_1x_kay.h
@@ -70,7 +70,7 @@ struct data_key {
 	Boolean rx_latest;
 	Boolean tx_latest;
 
-	int user;  /* FIXME: to indicate if it can be delete safely */
+	int user;
 
 	struct dl_list list;
 };
-- 
2.10.0