From 78222bacfca97cb18505df1ba5f3591864498a7e Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 11 Apr 2022 13:01:19 +0200 Subject: [PATCH] netfilter: cttimeout: decouple unlink and free on netns destruction Make it so netns pre_exit unlinks the objects from the pernet list, so they cannot be found anymore. netns core issues a synchronize_rcu() before calling the exit hooks so any the time the exit hooks run unconfirmed nf_conn entries have been free'd or they have been committed to the hashtable. The exit hook still tags unconfirmed entries as dying, this can now be removed in a followup change. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_conntrack_timeout.h | 8 ------ net/netfilter/nfnetlink_cttimeout.c | 30 ++++++++++++++++++-- 2 files changed, 28 insertions(+), 10 deletions(-) diff --git a/include/net/netfilter/nf_conntrack_timeout.h b/include/net/netfilter/nf_conntrack_timeout.h index 3ea94f6f3844..fea258983d23 100644 --- a/include/net/netfilter/nf_conntrack_timeout.h +++ b/include/net/netfilter/nf_conntrack_timeout.h @@ -17,14 +17,6 @@ struct nf_ct_timeout { char data[]; }; -struct ctnl_timeout { - struct list_head head; - struct rcu_head rcu_head; - refcount_t refcnt; - char name[CTNL_TIMEOUT_NAME_MAX]; - struct nf_ct_timeout timeout; -}; - struct nf_conn_timeout { struct nf_ct_timeout __rcu *timeout; }; diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index eea486f32971..83fa15c4193c 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -33,8 +33,19 @@ static unsigned int nfct_timeout_id __read_mostly; +struct ctnl_timeout { + struct list_head head; + struct rcu_head rcu_head; + refcount_t refcnt; + char name[CTNL_TIMEOUT_NAME_MAX]; + struct nf_ct_timeout timeout; + + struct list_head free_head; +}; + struct nfct_timeout_pernet { struct list_head nfct_timeout_list; + struct list_head nfct_timeout_freelist; }; MODULE_LICENSE("GPL"); @@ -574,10 +585,24 @@ static int __net_init cttimeout_net_init(struct net *net) struct nfct_timeout_pernet *pernet = nfct_timeout_pernet(net); INIT_LIST_HEAD(&pernet->nfct_timeout_list); + INIT_LIST_HEAD(&pernet->nfct_timeout_freelist); return 0; } +static void __net_exit cttimeout_net_pre_exit(struct net *net) +{ + struct nfct_timeout_pernet *pernet = nfct_timeout_pernet(net); + struct ctnl_timeout *cur, *tmp; + + list_for_each_entry_safe(cur, tmp, &pernet->nfct_timeout_list, head) { + list_del_rcu(&cur->head); + list_add(&cur->free_head, &pernet->nfct_timeout_freelist); + } + + /* core calls synchronize_rcu() after this */ +} + static void __net_exit cttimeout_net_exit(struct net *net) { struct nfct_timeout_pernet *pernet = nfct_timeout_pernet(net); @@ -586,8 +611,8 @@ static void __net_exit cttimeout_net_exit(struct net *net) nf_ct_unconfirmed_destroy(net); nf_ct_untimeout(net, NULL); - list_for_each_entry_safe(cur, tmp, &pernet->nfct_timeout_list, head) { - list_del_rcu(&cur->head); + list_for_each_entry_safe(cur, tmp, &pernet->nfct_timeout_freelist, head) { + list_del(&cur->free_head); if (refcount_dec_and_test(&cur->refcnt)) kfree_rcu(cur, rcu_head); @@ -596,6 +621,7 @@ static void __net_exit cttimeout_net_exit(struct net *net) static struct pernet_operations cttimeout_ops = { .init = cttimeout_net_init, + .pre_exit = cttimeout_net_pre_exit, .exit = cttimeout_net_exit, .id = &nfct_timeout_id, .size = sizeof(struct nfct_timeout_pernet),