From: Florian Westphal Date: Thu, 26 Aug 2021 13:54:22 +0000 (+0200) Subject: netfilter: refuse insertion if chain has grown too large X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=d7e7747ac5c;p=uclinux-h8%2Flinux.git netfilter: refuse insertion if chain has grown too large Also add a stat counter for this that gets exported both via old /proc interface and ctnetlink. Assuming the old default size of 16536 buckets and max hash occupancy of 64k, this results in 128k insertions (origin+reply), so ~8 entries per chain on average. The revised settings in this series will result in about two entries per bucket on average. This allows a hard-limit ceiling of 64. This is not tunable at the moment, but its possible to either increase nf_conntrack_buckets or decrease nf_conntrack_max to reduce average lengths. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- diff --git a/include/linux/netfilter/nf_conntrack_common.h b/include/linux/netfilter/nf_conntrack_common.h index 0c7d8d1e945d..700ea077ce2d 100644 --- a/include/linux/netfilter/nf_conntrack_common.h +++ b/include/linux/netfilter/nf_conntrack_common.h @@ -18,6 +18,7 @@ struct ip_conntrack_stat { unsigned int expect_create; unsigned int expect_delete; unsigned int search_restart; + unsigned int chaintoolong; }; #define NFCT_INFOMASK 7UL diff --git a/include/uapi/linux/netfilter/nfnetlink_conntrack.h b/include/uapi/linux/netfilter/nfnetlink_conntrack.h index d8484be72fdc..5ade231f497b 100644 --- a/include/uapi/linux/netfilter/nfnetlink_conntrack.h +++ b/include/uapi/linux/netfilter/nfnetlink_conntrack.h @@ -257,6 +257,7 @@ enum ctattr_stats_cpu { CTA_STATS_ERROR, CTA_STATS_SEARCH_RESTART, CTA_STATS_CLASH_RESOLVE, + CTA_STATS_CHAIN_TOOLONG, __CTA_STATS_MAX, }; #define CTA_STATS_MAX (__CTA_STATS_MAX - 1) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index da2650f872e1..94e18fb9690d 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -77,6 +77,8 @@ static __read_mostly bool nf_conntrack_locks_all; #define GC_SCAN_INTERVAL (120u * HZ) #define GC_SCAN_MAX_DURATION msecs_to_jiffies(10) +#define MAX_CHAINLEN 64u + static struct conntrack_gc_work conntrack_gc_work; void nf_conntrack_lock(spinlock_t *lock) __acquires(lock) @@ -840,7 +842,9 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) unsigned int hash, reply_hash; struct nf_conntrack_tuple_hash *h; struct hlist_nulls_node *n; + unsigned int chainlen = 0; unsigned int sequence; + int err = -EEXIST; zone = nf_ct_zone(ct); @@ -854,15 +858,24 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) } while (nf_conntrack_double_lock(net, hash, reply_hash, sequence)); /* See if there's one in the list already, including reverse */ - hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) + hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) { if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, zone, net)) goto out; - hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) + if (chainlen++ > MAX_CHAINLEN) + goto chaintoolong; + } + + chainlen = 0; + + hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) { if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, zone, net)) goto out; + if (chainlen++ > MAX_CHAINLEN) + goto chaintoolong; + } smp_wmb(); /* The caller holds a reference to this object */ @@ -872,11 +885,13 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) NF_CT_STAT_INC(net, insert); local_bh_enable(); return 0; - +chaintoolong: + NF_CT_STAT_INC(net, chaintoolong); + err = -ENOSPC; out: nf_conntrack_double_unlock(hash, reply_hash); local_bh_enable(); - return -EEXIST; + return err; } EXPORT_SYMBOL_GPL(nf_conntrack_hash_check_insert); @@ -1089,6 +1104,7 @@ int __nf_conntrack_confirm(struct sk_buff *skb) { const struct nf_conntrack_zone *zone; + unsigned int chainlen = 0, sequence; unsigned int hash, reply_hash; struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; @@ -1096,7 +1112,6 @@ __nf_conntrack_confirm(struct sk_buff *skb) struct hlist_nulls_node *n; enum ip_conntrack_info ctinfo; struct net *net; - unsigned int sequence; int ret = NF_DROP; ct = nf_ct_get(skb, &ctinfo); @@ -1156,15 +1171,28 @@ __nf_conntrack_confirm(struct sk_buff *skb) /* See if there's one in the list already, including reverse: NAT could have grabbed it without realizing, since we're not in the hash. If there is, we lost race. */ - hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) + hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) { if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, zone, net)) goto out; + if (chainlen++ > MAX_CHAINLEN) + goto chaintoolong; + } - hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) + chainlen = 0; + hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) { if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, zone, net)) goto out; + if (chainlen++ > MAX_CHAINLEN) { +chaintoolong: + nf_ct_add_to_dying_list(ct); + NF_CT_STAT_INC(net, chaintoolong); + NF_CT_STAT_INC(net, insert_failed); + ret = NF_DROP; + goto dying; + } + } /* Timer relative to confirmation time, not original setting time, otherwise we'd get timer wrap in diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index e81af33b233b..3f081ae08266 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -2484,7 +2484,9 @@ ctnetlink_ct_stat_cpu_fill_info(struct sk_buff *skb, u32 portid, u32 seq, nla_put_be32(skb, CTA_STATS_SEARCH_RESTART, htonl(st->search_restart)) || nla_put_be32(skb, CTA_STATS_CLASH_RESOLVE, - htonl(st->clash_resolve))) + htonl(st->clash_resolve)) || + nla_put_be32(skb, CTA_STATS_CHAIN_TOOLONG, + htonl(st->chaintoolong))) goto nla_put_failure; nlmsg_end(skb, nlh); diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index e84b499b7bfa..f94ebd5194b5 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -429,7 +429,7 @@ static int ct_cpu_seq_show(struct seq_file *seq, void *v) unsigned int nr_conntracks; if (v == SEQ_START_TOKEN) { - seq_puts(seq, "entries clashres found new invalid ignore delete delete_list insert insert_failed drop early_drop icmp_error expect_new expect_create expect_delete search_restart\n"); + seq_puts(seq, "entries clashres found new invalid ignore delete chainlength insert insert_failed drop early_drop icmp_error expect_new expect_create expect_delete search_restart\n"); return 0; } @@ -444,7 +444,7 @@ static int ct_cpu_seq_show(struct seq_file *seq, void *v) st->invalid, 0, 0, - 0, + st->chaintoolong, st->insert, st->insert_failed, st->drop,