Hi, On Tue, 17 Oct 2023, Pablo Neira Ayuso wrote: > This means then that Jozsef's patch is fixing the issue that you > reported, then a Tested-by: tag would be nice to have from you :) > > If all is OK, then please, let Jozsef submit his own patch to > netfilter-devel@ so it can follow its trip to the nf.git tree. I'll need a few days to work on the patch for possible improvements before the final submission. Best regards, Jozsef > On Tue, Oct 17, 2023 at 08:52:56PM +0800, xiaolinkui wrote: > > From: Linkui Xiao <xiaolinkui@xxxxxxxxxx> > > > > There is a race condition which can be demonstrated by the following > > script: > > > > ipset create hash_ip1 hash:net family inet hashsize 1024 maxelem 1048576 > > ipset add hash_ip1 172.20.0.0/16 > > ipset add hash_ip1 192.168.0.0/16 > > iptables -A INPUT -m set --match-set hash_ip1 src -j ACCEPT > > while [ 1 ] > > do > > ipset create hash_ip2 hash:net family inet hashsize 1024 maxelem 1048576 > > ipset add hash_ip2 172.20.0.0/16 > > ipset swap hash_ip1 hash_ip2 > > ipset destroy hash_ip2 > > sleep 0.05 > > done > > > > Swap will exchange the values of ref so destroy will see ref = 0 instead of > > ref = 1. So after running this script for a period of time, the following > > race situations may occur: > > CPU0: CPU1: > > ipt_do_table > > ->set_match_v4 > > ->ip_set_test > > ipset swap hash_ip1 hash_ip2 > > ipset destroy hash_ip2 > > ->hash_net4_kadt > > > > CPU0 found ipset through the index, and at this time, hash_ip2 has been > > destroyed by CPU1 through name search. So CPU0 will crash when accessing > > set->data in the function hash_net4_kadt. > > > > With this fix in place swap will wait for the ongoing operations to be > > finished. > > > > V1->V2 changes: > > - replace ref_netlink with rcu synchonize_rcu() > > > > Closes: https://lore.kernel.org/all/69e7963b-e7f8-3ad0-210-7b86eebf7f78@xxxxxxxxxxxxx/ > > Cc: stable@xxxxxxxxxxxxxxx > > Suggested-by: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx> > > Signed-off-by: Linkui Xiao <xiaolinkui@xxxxxxxxxx> > > > > --- > > net/netfilter/ipset/ip_set_core.c | 31 ++++++++++++++++++++++++++----- > > 1 file changed, 26 insertions(+), 5 deletions(-) > > > > diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c > > index 35d2f9c9ada0..62ee4de6ffee 100644 > > --- a/net/netfilter/ipset/ip_set_core.c > > +++ b/net/netfilter/ipset/ip_set_core.c > > @@ -712,13 +712,18 @@ ip_set_rcu_get(struct net *net, ip_set_id_t index) > > struct ip_set_net *inst = ip_set_pernet(net); > > > > rcu_read_lock(); > > - /* ip_set_list itself needs to be protected */ > > + /* ip_set_list and the set pointer need to be protected */ > > set = rcu_dereference(inst->ip_set_list)[index]; > > - rcu_read_unlock(); > > > > return set; > > } > > > > +static inline void > > +ip_set_rcu_put(struct ip_set *set __always_unused) > > +{ > > + rcu_read_unlock(); > > +} > > + > > static inline void > > ip_set_lock(struct ip_set *set) > > { > > @@ -744,8 +749,10 @@ ip_set_test(ip_set_id_t index, const struct sk_buff *skb, > > pr_debug("set %s, index %u\n", set->name, index); > > > > if (opt->dim < set->type->dimension || > > - !(opt->family == set->family || set->family == NFPROTO_UNSPEC)) > > + !(opt->family == set->family || set->family == NFPROTO_UNSPEC)) { > > + ip_set_rcu_put(set); > > return 0; > > + } > > > > ret = set->variant->kadt(set, skb, par, IPSET_TEST, opt); > > > > @@ -764,6 +771,7 @@ ip_set_test(ip_set_id_t index, const struct sk_buff *skb, > > ret = -ret; > > } > > > > + ip_set_rcu_put(set); > > /* Convert error codes to nomatch */ > > return (ret < 0 ? 0 : ret); > > } > > @@ -780,12 +788,15 @@ ip_set_add(ip_set_id_t index, const struct sk_buff *skb, > > pr_debug("set %s, index %u\n", set->name, index); > > > > if (opt->dim < set->type->dimension || > > - !(opt->family == set->family || set->family == NFPROTO_UNSPEC)) > > + !(opt->family == set->family || set->family == NFPROTO_UNSPEC)) { > > + ip_set_rcu_put(set); > > return -IPSET_ERR_TYPE_MISMATCH; > > + } > > > > ip_set_lock(set); > > ret = set->variant->kadt(set, skb, par, IPSET_ADD, opt); > > ip_set_unlock(set); > > + ip_set_rcu_put(set); > > > > return ret; > > } > > @@ -802,12 +813,15 @@ ip_set_del(ip_set_id_t index, const struct sk_buff *skb, > > pr_debug("set %s, index %u\n", set->name, index); > > > > if (opt->dim < set->type->dimension || > > - !(opt->family == set->family || set->family == NFPROTO_UNSPEC)) > > + !(opt->family == set->family || set->family == NFPROTO_UNSPEC)) { > > + ip_set_rcu_put(set); > > return -IPSET_ERR_TYPE_MISMATCH; > > + } > > > > ip_set_lock(set); > > ret = set->variant->kadt(set, skb, par, IPSET_DEL, opt); > > ip_set_unlock(set); > > + ip_set_rcu_put(set); > > > > return ret; > > } > > @@ -882,6 +896,7 @@ ip_set_name_byindex(struct net *net, ip_set_id_t index, char *name) > > read_lock_bh(&ip_set_ref_lock); > > strscpy_pad(name, set->name, IPSET_MAXNAMELEN); > > read_unlock_bh(&ip_set_ref_lock); > > + ip_set_rcu_put(set); > > } > > EXPORT_SYMBOL_GPL(ip_set_name_byindex); > > > > @@ -1348,6 +1363,9 @@ static int ip_set_rename(struct sk_buff *skb, const struct nfnl_info *info, > > * protected by the ip_set_ref_lock. The kernel interfaces > > * do not hold the mutex but the pointer settings are atomic > > * so the ip_set_list always contains valid pointers to the sets. > > + * However after swapping, a userspace set destroy command could > > + * remove a set still processed by kernel side add/del/test. > > + * Therefore we need to wait for the ongoing operations to be finished. > > */ > > > > static int ip_set_swap(struct sk_buff *skb, const struct nfnl_info *info, > > @@ -1397,6 +1415,9 @@ static int ip_set_swap(struct sk_buff *skb, const struct nfnl_info *info, > > 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; > > } > > > > -- > > 2.17.1 > > > -- E-mail : kadlec@xxxxxxxxxxxxxxxxx, kadlecsik.jozsef@xxxxxxxxx PGP key : https://wigner.hu/~kadlec/pgp_public_key.txt Address : Wigner Research Centre for Physics H-1525 Budapest 114, POB. 49, Hungary
