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authorJozsef Kadlecsik <kadlec@netfilter.org>2024-01-29 12:30:23 +0100
committerJozsef Kadlecsik <kadlec@netfilter.org>2024-01-29 12:30:23 +0100
commit148fad4dcc41bd07b52ed3ccca5f40765e9cf692 (patch)
tree8dabf3d719bfc7875f6c71254aca764821f27025
parent0378d91222c1aba5a766c3d745574ed1c59cbf8f (diff)
netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test v4
The patch "netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test", commit 28628fa9 fixes a race condition. But the synchronize_rcu() added to the swap function unnecessarily slows it down: it can safely be moved to destroy and use call_rcu() instead. Eric Dumazet pointed out that simply calling the destroy functions as rcu callback does not work: sets with timeout use garbage collectors which need cancelling at destroy which can wait. Therefore the destroy functions are split into two: cancelling garbage collectors safely at executing the command received by netlink and moving the remaining part only into the rcu callback. Link: https://lore.kernel.org/lkml/C0829B10-EAA6-4809-874E-E1E9C05A8D84@automattic.com/ Fixes: 28628fa952fe ("netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test") Reported-by: Ale Crismani <ale.crismani@automattic.com> Reported-by: David Wang <00107082@163.com> Tested-by: David Wang <00107082@163.com> Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
-rw-r--r--kernel/include/linux/netfilter/ipset/ip_set.h4
-rw-r--r--kernel/net/netfilter/ipset/ip_set_bitmap_gen.h14
-rw-r--r--kernel/net/netfilter/ipset/ip_set_core.c38
-rw-r--r--kernel/net/netfilter/ipset/ip_set_hash_gen.h15
-rw-r--r--kernel/net/netfilter/ipset/ip_set_list_set.c13
5 files changed, 65 insertions, 19 deletions
diff --git a/kernel/include/linux/netfilter/ipset/ip_set.h b/kernel/include/linux/netfilter/ipset/ip_set.h
index 0c6eee2..7691b7a 100644
--- a/kernel/include/linux/netfilter/ipset/ip_set.h
+++ b/kernel/include/linux/netfilter/ipset/ip_set.h
@@ -189,6 +189,8 @@ struct ip_set_type_variant {
/* Return true if "b" set is the same as "a"
* according to the create set parameters */
bool (*same_set)(const struct ip_set *a, const struct ip_set *b);
+ /* Cancel ongoing garbage collectors before destroying the set*/
+ void (*cancel_gc)(struct ip_set *set);
/* Region-locking is used */
bool region_lock;
};
@@ -245,6 +247,8 @@ extern void ip_set_type_unregister(struct ip_set_type *set_type);
/* A generic IP set */
struct ip_set {
+ /* For call_cru in destroy */
+ struct rcu_head rcu;
/* The name of the set */
char name[IPSET_MAXNAMELEN];
/* Lock protecting the set data */
diff --git a/kernel/net/netfilter/ipset/ip_set_bitmap_gen.h b/kernel/net/netfilter/ipset/ip_set_bitmap_gen.h
index 0479750..3245b6b 100644
--- a/kernel/net/netfilter/ipset/ip_set_bitmap_gen.h
+++ b/kernel/net/netfilter/ipset/ip_set_bitmap_gen.h
@@ -29,6 +29,7 @@
#define mtype_del IPSET_TOKEN(MTYPE, _del)
#define mtype_list IPSET_TOKEN(MTYPE, _list)
#define mtype_gc IPSET_TOKEN(MTYPE, _gc)
+#define mtype_cancel_gc IPSET_TOKEN(MTYPE, _cancel_gc)
#define mtype MTYPE
#define get_ext(set, map, id) ((map)->extensions + ((set)->dsize * (id)))
@@ -58,9 +59,6 @@ mtype_destroy(struct ip_set *set)
{
struct mtype *map = set->data;
- if (SET_WITH_TIMEOUT(set))
- del_timer_sync(&map->gc);
-
if (set->dsize && set->extensions & IPSET_EXT_DESTROY)
mtype_ext_cleanup(set);
ip_set_free(map->members);
@@ -290,6 +288,15 @@ mtype_gc(GC_ARG)
add_timer(&map->gc);
}
+static void
+mtype_cancel_gc(struct ip_set *set)
+{
+ struct mtype *map = set->data;
+
+ if (SET_WITH_TIMEOUT(set))
+ del_timer_sync(&map->gc);
+}
+
static const struct ip_set_type_variant mtype = {
.kadt = mtype_kadt,
.uadt = mtype_uadt,
@@ -303,6 +310,7 @@ static const struct ip_set_type_variant mtype = {
.head = mtype_head,
.list = mtype_list,
.same_set = mtype_same_set,
+ .cancel_gc = mtype_cancel_gc,
};
#endif /* __IP_SET_BITMAP_IP_GEN_H */
diff --git a/kernel/net/netfilter/ipset/ip_set_core.c b/kernel/net/netfilter/ipset/ip_set_core.c
index 3a93fd5..126312d 100644
--- a/kernel/net/netfilter/ipset/ip_set_core.c
+++ b/kernel/net/netfilter/ipset/ip_set_core.c
@@ -1192,6 +1192,14 @@ ip_set_destroy_set(struct ip_set *set)
kfree(set);
}
+static void
+ip_set_destroy_set_rcu(struct rcu_head *head)
+{
+ struct ip_set *set = container_of(head, struct ip_set, rcu);
+
+ ip_set_destroy_set(set);
+}
+
static int
IPSET_CBFN(ip_set_destroy, struct net *net, struct sock *ctnl,
struct sk_buff *skb, const struct nlmsghdr *nlh,
@@ -1207,9 +1215,6 @@ IPSET_CBFN(ip_set_destroy, struct net *net, struct sock *ctnl,
if (unlikely(protocol_min_failed(attr)))
return -IPSET_ERR_PROTOCOL;
- /* Must wait for flush to be really finished in list:set */
- rcu_barrier();
-
/* Commands are serialized and references are
* protected by the ip_set_ref_lock.
* External systems (i.e. xt_set) must call
@@ -1220,8 +1225,10 @@ IPSET_CBFN(ip_set_destroy, struct net *net, struct sock *ctnl,
* counter, so if it's already zero, we can proceed
* without holding the lock.
*/
- read_lock_bh(&ip_set_ref_lock);
if (!attr[IPSET_ATTR_SETNAME]) {
+ /* Must wait for flush to be really finished in list:set */
+ rcu_barrier();
+ read_lock_bh(&ip_set_ref_lock);
for (i = 0; i < inst->ip_set_max; i++) {
s = ip_set(inst, i);
if (s && (s->ref || s->ref_netlink)) {
@@ -1235,6 +1242,8 @@ IPSET_CBFN(ip_set_destroy, struct net *net, struct sock *ctnl,
s = ip_set(inst, i);
if (s) {
ip_set(inst, i) = NULL;
+ /* Must cancel garbage collectors */
+ s->variant->cancel_gc(s);
ip_set_destroy_set(s);
}
}
@@ -1242,6 +1251,9 @@ IPSET_CBFN(ip_set_destroy, struct net *net, struct sock *ctnl,
inst->is_destroyed = false;
} else {
u32 flags = flag_exist(INFO_NLH(info, nlh));
+ u16 features = 0;
+
+ read_lock_bh(&ip_set_ref_lock);
s = find_set_and_id(inst, nla_data(attr[IPSET_ATTR_SETNAME]),
&i);
if (!s) {
@@ -1252,10 +1264,16 @@ IPSET_CBFN(ip_set_destroy, struct net *net, struct sock *ctnl,
ret = -IPSET_ERR_BUSY;
goto out;
}
+ features = s->type->features;
ip_set(inst, i) = NULL;
read_unlock_bh(&ip_set_ref_lock);
-
- ip_set_destroy_set(s);
+ if (features & IPSET_TYPE_NAME) {
+ /* Must wait for flush to be really finished */
+ rcu_barrier();
+ }
+ /* Must cancel garbage collectors */
+ s->variant->cancel_gc(s);
+ call_rcu(&s->rcu, ip_set_destroy_set_rcu);
}
return 0;
out:
@@ -1420,9 +1438,6 @@ IPSET_CBFN(ip_set_swap, struct net *net, struct sock *ctnl,
ip_set(inst, to_id) = from;
write_unlock_bh(&ip_set_ref_lock);
- /* Make sure all readers of the old set pointers are completed. */
- synchronize_rcu();
-
return 0;
}
@@ -2540,8 +2555,11 @@ ip_set_fini(void)
{
nf_unregister_sockopt(&so_set);
nfnetlink_subsys_unregister(&ip_set_netlink_subsys);
-
UNREGISTER_PERNET_SUBSYS(&ip_set_net_ops);
+
+ /* Wait for call_rcu() in destroy */
+ rcu_barrier();
+
pr_debug("these are the famous last words\n");
}
diff --git a/kernel/net/netfilter/ipset/ip_set_hash_gen.h b/kernel/net/netfilter/ipset/ip_set_hash_gen.h
index af38991..a88acf4 100644
--- a/kernel/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/kernel/net/netfilter/ipset/ip_set_hash_gen.h
@@ -222,6 +222,7 @@ static const union nf_inet_addr zeromask = {};
#undef mtype_gc_do
#undef mtype_gc
#undef mtype_gc_init
+#undef mtype_cancel_gc
#undef mtype_variant
#undef mtype_data_match
@@ -266,6 +267,7 @@ static const union nf_inet_addr zeromask = {};
#define mtype_gc_do IPSET_TOKEN(MTYPE, _gc_do)
#define mtype_gc IPSET_TOKEN(MTYPE, _gc)
#define mtype_gc_init IPSET_TOKEN(MTYPE, _gc_init)
+#define mtype_cancel_gc IPSET_TOKEN(MTYPE, _cancel_gc)
#define mtype_variant IPSET_TOKEN(MTYPE, _variant)
#define mtype_data_match IPSET_TOKEN(MTYPE, _data_match)
@@ -450,9 +452,6 @@ mtype_destroy(struct ip_set *set)
struct htype *h = set->data;
struct list_head *l, *lt;
- if (SET_WITH_TIMEOUT(set))
- cancel_delayed_work_sync(&h->gc.dwork);
-
mtype_ahash_destroy(set, ipset_dereference_nfnl(h->table), true);
list_for_each_safe(l, lt, &h->ad) {
list_del(l);
@@ -598,6 +597,15 @@ mtype_gc_init(struct htable_gc *gc)
queue_delayed_work(system_power_efficient_wq, &gc->dwork, HZ);
}
+static void
+mtype_cancel_gc(struct ip_set *set)
+{
+ struct htype *h = set->data;
+
+ if (SET_WITH_TIMEOUT(set))
+ cancel_delayed_work_sync(&h->gc.dwork);
+}
+
static int
mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext,
struct ip_set_ext *mext, u32 flags);
@@ -1441,6 +1449,7 @@ static const struct ip_set_type_variant mtype_variant = {
.uref = mtype_uref,
.resize = mtype_resize,
.same_set = mtype_same_set,
+ .cancel_gc = mtype_cancel_gc,
.region_lock = true,
};
diff --git a/kernel/net/netfilter/ipset/ip_set_list_set.c b/kernel/net/netfilter/ipset/ip_set_list_set.c
index 8c7fef8..d7d487c 100644
--- a/kernel/net/netfilter/ipset/ip_set_list_set.c
+++ b/kernel/net/netfilter/ipset/ip_set_list_set.c
@@ -429,9 +429,6 @@ list_set_destroy(struct ip_set *set)
struct list_set *map = set->data;
struct set_elem *e, *n;
- if (SET_WITH_TIMEOUT(set))
- del_timer_sync(&map->gc);
-
list_for_each_entry_safe(e, n, &map->members, list) {
list_del(&e->list);
ip_set_put_byindex(map->net, e->id);
@@ -548,6 +545,15 @@ list_set_same_set(const struct ip_set *a, const struct ip_set *b)
a->extensions == b->extensions;
}
+static void
+list_set_cancel_gc(struct ip_set *set)
+{
+ struct list_set *map = set->data;
+
+ if (SET_WITH_TIMEOUT(set))
+ del_timer_sync(&map->gc);
+}
+
static const struct ip_set_type_variant set_variant = {
.kadt = list_set_kadt,
.uadt = list_set_uadt,
@@ -561,6 +567,7 @@ static const struct ip_set_type_variant set_variant = {
.head = list_set_head,
.list = list_set_list,
.same_set = list_set_same_set,
+ .cancel_gc = list_set_cancel_gc,
};
static void