netfilter: use rcu_dereference_protected()

Restore the rcu_dereference() calls in conntrack/expectation notifier
and logger registration/unregistration, but use the _protected variant,
which will be required by the upcoming __rcu annotations.

Based on patch by Eric Dumazet <eric.dumazet@gmail.com>

Signed-off-by: Patrick McHardy <kaber@trash.net>

2 files changed, 26 insertions, 6 deletions

diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
index a94ac3ad02cb..cdcc7649476b 100644
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -82,9 +82,12 @@ EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
 int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)
 {
         int ret = 0;
+        struct nf_ct_event_notifier *notify;
 
         mutex_lock(&nf_ct_ecache_mutex);
-        if (nf_conntrack_event_cb != NULL) {
+        notify = rcu_dereference_protected(nf_conntrack_event_cb,
+                                           lockdep_is_held(&nf_ct_ecache_mutex));
+        if (notify != NULL) {
                 ret = -EBUSY;
                 goto out_unlock;
         }
@@ -100,8 +103,12 @@ EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 
 void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
 {
+        struct nf_ct_event_notifier *notify;
+
         mutex_lock(&nf_ct_ecache_mutex);
-        BUG_ON(nf_conntrack_event_cb != new);
+        notify = rcu_dereference_protected(nf_conntrack_event_cb,
+                                           lockdep_is_held(&nf_ct_ecache_mutex));
+        BUG_ON(notify != new);
         rcu_assign_pointer(nf_conntrack_event_cb, NULL);
         mutex_unlock(&nf_ct_ecache_mutex);
 }
@@ -110,9 +117,12 @@ EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
 {
         int ret = 0;
+        struct nf_exp_event_notifier *notify;
 
         mutex_lock(&nf_ct_ecache_mutex);
-        if (nf_expect_event_cb != NULL) {
+        notify = rcu_dereference_protected(nf_expect_event_cb,
+                                           lockdep_is_held(&nf_ct_ecache_mutex));
+        if (notify != NULL) {
                 ret = -EBUSY;
                 goto out_unlock;
         }
@@ -128,8 +138,12 @@ EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 
 void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
 {
+        struct nf_exp_event_notifier *notify;
+
         mutex_lock(&nf_ct_ecache_mutex);
-        BUG_ON(nf_expect_event_cb != new);
+        notify = rcu_dereference_protected(nf_expect_event_cb,
+                                           lockdep_is_held(&nf_ct_ecache_mutex));
+        BUG_ON(notify != new);
         rcu_assign_pointer(nf_expect_event_cb, NULL);
         mutex_unlock(&nf_ct_ecache_mutex);
 }
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 908f59935fbb..7df37fd786bc 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -35,6 +35,7 @@ static struct nf_logger *__find_logger(int pf, const char *str_logger)
 /* return EEXIST if the same logger is registred, 0 on success. */
 int nf_log_register(u_int8_t pf, struct nf_logger *logger)
 {
+        const struct nf_logger *llog;
         int i;
 
         if (pf >= ARRAY_SIZE(nf_loggers))
@@ -51,7 +52,9 @@ int nf_log_register(u_int8_t pf, struct nf_logger *logger)
         } else {
                 /* register at end of list to honor first register win */
                 list_add_tail(&logger->list[pf], &nf_loggers_l[pf]);
-                if (nf_loggers[pf] == NULL)
+                llog = rcu_dereference_protected(nf_loggers[pf],
+                                                 lockdep_is_held(&nf_log_mutex));
+                if (llog == NULL)
                         rcu_assign_pointer(nf_loggers[pf], logger);
         }
 
@@ -63,11 +66,14 @@ EXPORT_SYMBOL(nf_log_register);
 
 void nf_log_unregister(struct nf_logger *logger)
 {
+        const struct nf_logger *c_logger;
         int i;
 
         mutex_lock(&nf_log_mutex);
         for (i = 0; i < ARRAY_SIZE(nf_loggers); i++) {
-                if (nf_loggers[i] == logger)
+                c_logger = rcu_dereference_protected(nf_loggers[i],
+                                                     lockdep_is_held(&nf_log_mutex));
+                if (c_logger == logger)
                         rcu_assign_pointer(nf_loggers[i], NULL);
                 list_del(&logger->list[i]);
         }