Hi Sasha,

This fix requires a follow up to silence a RCU suspicious usage warning.

Please, hold on until end of the week with this.

I will get back to you with a reminder if it helps.

Thanks.

On Mon, Jun 17, 2024 at 07:33:41AM -0400, Sasha Levin wrote:

This is a note to let you know that I've just added the patch titled

netfilter: ipset: Fix race between namespace cleanup and gc in the list:set type

to the 6.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: netfilter-ipset-fix-race-between-namespace-cleanup-a.patch and it can be found in the queue-6.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

commit c93a9ac4a5e09f694873b3abca7eb42c93f34220 Author: Jozsef Kadlecsik kadlec@netfilter.org Date: Tue Jun 4 15:58:03 2024 +0200

netfilter: ipset: Fix race between namespace cleanup and gc in the list:set type

[ Upstream commit 4e7aaa6b82d63e8ddcbfb56b4fd3d014ca586f10 ] Lion Ackermann reported that there is a race condition between namespace cleanup in ipset and the garbage collection of the list:set type. The namespace cleanup can destroy the list:set type of sets while the gc of the set type is waiting to run in rcu cleanup. The latter uses data from the destroyed set which thus leads use after free. The patch contains the following parts: - When destroying all sets, first remove the garbage collectors, then wait if needed and then destroy the sets. - Fix the badly ordered "wait then remove gc" for the destroy a single set case. - Fix the missing rcu locking in the list:set type in the userspace test case. - Use proper RCU list handlings in the list:set type. The patch depends on c1193d9bbbd3 (netfilter: ipset: Add list flush to cancel_gc). Fixes: 97f7cf1cd80e (netfilter: ipset: fix performance regression in swap operation) Reported-by: Lion Ackermann nnamrec@gmail.com Tested-by: Lion Ackermann nnamrec@gmail.com Signed-off-by: Jozsef Kadlecsik kadlec@netfilter.org Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c index 3184cc6be4c9d..c7ae4d9bf3d24 100644 --- a/net/netfilter/ipset/ip_set_core.c +++ b/net/netfilter/ipset/ip_set_core.c @@ -1172,23 +1172,50 @@ ip_set_setname_policy[IPSET_ATTR_CMD_MAX + 1] = { .len = IPSET_MAXNAMELEN - 1 }, }; +/* In order to return quickly when destroying a single set, it is split

• • into two stages:
• • • Cancel garbage collector
• • • Destroy the set itself via call_rcu()
• */

static void -ip_set_destroy_set(struct ip_set *set) +ip_set_destroy_set_rcu(struct rcu_head *head) {

• pr_debug("set: %s\n", set->name);

• struct ip_set *set = container_of(head, struct ip_set, rcu);

• /* Must call it without holding any lock */ set->variant->destroy(set); module_put(set->type->me); kfree(set);

} static void -ip_set_destroy_set_rcu(struct rcu_head *head) +_destroy_all_sets(struct ip_set_net *inst) {

• struct ip_set *set = container_of(head, struct ip_set, rcu);

• struct ip_set *set;
• ip_set_id_t i;
• bool need_wait = false;

• ip_set_destroy_set(set);

• /* First cancel gc's: set:list sets are flushed as well */
• for (i = 0; i < inst->ip_set_max; i++) {

• set = ip_set(inst, i);
  

• if (set) {
  

• 	set->variant->cancel_gc(set);
  

• 	if (set->type->features & IPSET_TYPE_NAME)
  

• 		need_wait = true;
  

• }
  

• }
• /* Must wait for flush to be really finished */
• if (need_wait)

• rcu_barrier();
  

• for (i = 0; i < inst->ip_set_max; i++) {

• set = ip_set(inst, i);
  

• if (set) {
  

• 	ip_set(inst, i) = NULL;
  

• 	set->variant->destroy(set);
  

• 	module_put(set->type->me);
  

• 	kfree(set);
  

• }
  

• }

} static int ip_set_destroy(struct sk_buff *skb, const struct nfnl_info *info, @@ -1202,11 +1229,10 @@ static int ip_set_destroy(struct sk_buff *skb, const struct nfnl_info *info, if (unlikely(protocol_min_failed(attr))) return -IPSET_ERR_PROTOCOL;

• /* Commands are serialized and references are
  • protected by the ip_set_ref_lock.
  • External systems (i.e. xt_set) must call

• * ip_set_put|get_nfnl_* functions, that way we
  

• * ip_set_nfnl_get_* functions, that way we
  

  • can safely check references here.
  • list:set timer can only decrement the reference

@@ -1214,8 +1240,6 @@ static int ip_set_destroy(struct sk_buff *skb, const struct nfnl_info *info, * without holding the 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);

@@ -1226,15 +1250,7 @@ static int ip_set_destroy(struct sk_buff *skb, const struct nfnl_info *info, } inst->is_destroyed = true; read_unlock_bh(&ip_set_ref_lock);

• for (i = 0; i < inst->ip_set_max; i++) {
  

• 	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);
  

• 	}
  

• }
  

• _destroy_all_sets(inst);
  

  /* Modified by ip_set_destroy() only, which is serialized */ inst->is_destroyed = false; } else {

@@ -1255,12 +1271,12 @@ static int ip_set_destroy(struct sk_buff *skb, const struct nfnl_info *info, features = s->type->features; ip_set(inst, i) = NULL; read_unlock_bh(&ip_set_ref_lock);

• /* Must cancel garbage collectors */
  

• s->variant->cancel_gc(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;

@@ -2365,30 +2381,25 @@ ip_set_net_init(struct net *net) } static void __net_exit -ip_set_net_exit(struct net *net) +ip_set_net_pre_exit(struct net *net) { struct ip_set_net *inst = ip_set_pernet(net);

• struct ip_set *set = NULL;
• ip_set_id_t i;
• inst->is_deleted = true; /* flag for ip_set_nfnl_put */

+}

• nfnl_lock(NFNL_SUBSYS_IPSET);
• for (i = 0; i < inst->ip_set_max; i++) {

• set = ip_set(inst, i);
  

• if (set) {
  

• 	ip_set(inst, i) = NULL;
  

• 	set->variant->cancel_gc(set);
  

• 	ip_set_destroy_set(set);
  

• }
  

• }
• nfnl_unlock(NFNL_SUBSYS_IPSET);

+static void __net_exit +ip_set_net_exit(struct net *net) +{

• struct ip_set_net *inst = ip_set_pernet(net);
• _destroy_all_sets(inst); kvfree(rcu_dereference_protected(inst->ip_set_list, 1));

} static struct pernet_operations ip_set_net_ops = { .init = ip_set_net_init,

• .pre_exit = ip_set_net_pre_exit, .exit = ip_set_net_exit, .id = &ip_set_net_id, .size = sizeof(struct ip_set_net),

diff --git a/net/netfilter/ipset/ip_set_list_set.c b/net/netfilter/ipset/ip_set_list_set.c index 54e2a1dd7f5f5..bfae7066936bb 100644 --- a/net/netfilter/ipset/ip_set_list_set.c +++ b/net/netfilter/ipset/ip_set_list_set.c @@ -79,7 +79,7 @@ list_set_kadd(struct ip_set *set, const struct sk_buff *skb, struct set_elem *e; int ret;

• list_for_each_entry(e, &map->members, list) {

• list_for_each_entry_rcu(e, &map->members, list) { if (SET_WITH_TIMEOUT(set) && ip_set_timeout_expired(ext_timeout(e, set))) continue;

@@ -99,7 +99,7 @@ list_set_kdel(struct ip_set *set, const struct sk_buff *skb, struct set_elem *e; int ret;

• list_for_each_entry(e, &map->members, list) {

• list_for_each_entry_rcu(e, &map->members, list) { if (SET_WITH_TIMEOUT(set) && ip_set_timeout_expired(ext_timeout(e, set))) continue;

@@ -188,9 +188,10 @@ list_set_utest(struct ip_set *set, void *value, const struct ip_set_ext *ext, struct list_set *map = set->data; struct set_adt_elem *d = value; struct set_elem *e, *next, *prev = NULL;

• int ret;

• int ret = 0;

• list_for_each_entry(e, &map->members, list) {

• rcu_read_lock();
• list_for_each_entry_rcu(e, &map->members, list) { if (SET_WITH_TIMEOUT(set) && ip_set_timeout_expired(ext_timeout(e, set))) continue;

@@ -201,6 +202,7 @@ list_set_utest(struct ip_set *set, void *value, const struct ip_set_ext *ext, if (d->before == 0) { ret = 1;

• 	goto out;
  

  } else if (d->before > 0) { next = list_next_entry(e, list); ret = !list_is_last(&e->list, &map->members) &&

@@ -208,9 +210,11 @@ list_set_utest(struct ip_set *set, void *value, const struct ip_set_ext *ext, } else { ret = prev && prev->id == d->refid; }

• return ret;
  

• goto out;
  

  }

• return 0;

+out:

• rcu_read_unlock();
• return ret;

} static void @@ -239,7 +243,7 @@ list_set_uadd(struct ip_set *set, void *value, const struct ip_set_ext *ext, /* Find where to add the new entry */ n = prev = next = NULL;

• list_for_each_entry(e, &map->members, list) {

• list_for_each_entry_rcu(e, &map->members, list) { if (SET_WITH_TIMEOUT(set) && ip_set_timeout_expired(ext_timeout(e, set))) continue;

@@ -316,9 +320,9 @@ list_set_udel(struct ip_set *set, void *value, const struct ip_set_ext *ext, { struct list_set *map = set->data; struct set_adt_elem *d = value;

• struct set_elem *e, *next, *prev = NULL;

• struct set_elem *e, *n, *next, *prev = NULL;

• list_for_each_entry(e, &map->members, list) {

• list_for_each_entry_safe(e, n, &map->members, list) { if (SET_WITH_TIMEOUT(set) && ip_set_timeout_expired(ext_timeout(e, set))) continue;

@@ -424,14 +428,8 @@ static void list_set_destroy(struct ip_set *set) { struct list_set *map = set->data;

• struct set_elem *e, *n;

• list_for_each_entry_safe(e, n, &map->members, list) {

• list_del(&e->list);
  

• ip_set_put_byindex(map->net, e->id);
  

• ip_set_ext_destroy(set, e);
  

• kfree(e);
  

• }

• WARN_ON_ONCE(!list_empty(&map->members)); kfree(map);

set->data = NULL;