Hi again, Cc'ing Sebastian Gottschall too.
See below for details. Thanks. On Tue, Nov 14, 2017 at 04:54:10PM +0100, Pablo Neira Ayuso wrote: > Hi Greg, > > Please, hold on a bit with this revert patch entitled: > > nat: Revert "netfilter: nat: convert nat bysrc hash to rhashtable") > > > for 4.9-stable. > > Until we clarify what is going on. > > Guillame (he's on Cc) is reporting some problems after this. > > Thanks! > > On Mon, Nov 13, 2017 at 01:56:42PM +0100, Greg Kroah-Hartman wrote: > > 4.9-stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Florian Westphal <f...@strlen.de> > > > > commit e1bf1687740ce1a3598a1c5e452b852ff2190682 upstream. > > > > This reverts commit 870190a9ec9075205c0fa795a09fa931694a3ff1. > > > > It was not a good idea. The custom hash table was a much better > > fit for this purpose. > > > > A fast lookup is not essential, in fact for most cases there is no lookup > > at all because original tuple is not taken and can be used as-is. > > What needs to be fast is insertion and deletion. > > > > rhlist removal however requires a rhlist walk. > > We can have thousands of entries in such a list if source port/addresses > > are reused for multiple flows, if this happens removal requests are so > > expensive that deletions of a few thousand flows can take several > > seconds(!). > > > > The advantages that we got from rhashtable are: > > 1) table auto-sizing > > 2) multiple locks > > > > 1) would be nice to have, but it is not essential as we have at > > most one lookup per new flow, so even a million flows in the bysource > > table are not a problem compared to current deletion cost. > > 2) is easy to add to custom hash table. > > > > I tried to add hlist_node to rhlist to speed up rhltable_remove but this > > isn't doable without changing semantics. rhltable_remove_fast will > > check that the to-be-deleted object is part of the table and that > > requires a list walk that we want to avoid. > > > > Furthermore, using hlist_node increases size of struct rhlist_head, which > > in turn increases nf_conn size. > > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=196821 > > Reported-by: Ivan Babrou <ibob...@gmail.com> > > Signed-off-by: Florian Westphal <f...@strlen.de> > > Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org> > > Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> > > > > > > --- > > include/net/netfilter/nf_conntrack.h | 3 > > include/net/netfilter/nf_nat.h | 1 > > net/netfilter/nf_nat_core.c | 131 > > ++++++++++++++--------------------- > > 3 files changed, 56 insertions(+), 79 deletions(-) > > > > --- a/include/net/netfilter/nf_conntrack.h > > +++ b/include/net/netfilter/nf_conntrack.h > > @@ -17,7 +17,6 @@ > > #include <linux/bitops.h> > > #include <linux/compiler.h> > > #include <linux/atomic.h> > > -#include <linux/rhashtable.h> > > > > #include <linux/netfilter/nf_conntrack_tcp.h> > > #include <linux/netfilter/nf_conntrack_dccp.h> > > @@ -101,7 +100,7 @@ struct nf_conn { > > possible_net_t ct_net; > > > > #if IS_ENABLED(CONFIG_NF_NAT) > > - struct rhlist_head nat_bysource; > > + struct hlist_node nat_bysource; > > #endif > > /* all members below initialized via memset */ > > u8 __nfct_init_offset[0]; > > --- a/include/net/netfilter/nf_nat.h > > +++ b/include/net/netfilter/nf_nat.h > > @@ -1,6 +1,5 @@ > > #ifndef _NF_NAT_H > > #define _NF_NAT_H > > -#include <linux/rhashtable.h> > > #include <linux/netfilter_ipv4.h> > > #include <linux/netfilter/nf_nat.h> > > #include <net/netfilter/nf_conntrack_tuple.h> > > --- a/net/netfilter/nf_nat_core.c > > +++ b/net/netfilter/nf_nat_core.c > > @@ -30,19 +30,17 @@ > > #include <net/netfilter/nf_conntrack_zones.h> > > #include <linux/netfilter/nf_nat.h> > > > > +static DEFINE_SPINLOCK(nf_nat_lock); > > + > > static DEFINE_MUTEX(nf_nat_proto_mutex); > > static const struct nf_nat_l3proto __rcu *nf_nat_l3protos[NFPROTO_NUMPROTO] > > __read_mostly; > > static const struct nf_nat_l4proto __rcu > > **nf_nat_l4protos[NFPROTO_NUMPROTO] > > __read_mostly; > > > > -struct nf_nat_conn_key { > > - const struct net *net; > > - const struct nf_conntrack_tuple *tuple; > > - const struct nf_conntrack_zone *zone; > > -}; > > - > > -static struct rhltable nf_nat_bysource_table; > > +static struct hlist_head *nf_nat_bysource __read_mostly; > > +static unsigned int nf_nat_htable_size __read_mostly; > > +static unsigned int nf_nat_hash_rnd __read_mostly; > > > > inline const struct nf_nat_l3proto * > > __nf_nat_l3proto_find(u8 family) > > @@ -121,17 +119,19 @@ int nf_xfrm_me_harder(struct net *net, s > > EXPORT_SYMBOL(nf_xfrm_me_harder); > > #endif /* CONFIG_XFRM */ > > > > -static u32 nf_nat_bysource_hash(const void *data, u32 len, u32 seed) > > +/* We keep an extra hash for each conntrack, for fast searching. */ > > +static inline unsigned int > > +hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple) > > { > > - const struct nf_conntrack_tuple *t; > > - const struct nf_conn *ct = data; > > + unsigned int hash; > > + > > + get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd)); > > > > - t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; > > /* Original src, to ensure we map it consistently if poss. */ > > + hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32), > > + tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n)); > > > > - seed ^= net_hash_mix(nf_ct_net(ct)); > > - return jhash2((const u32 *)&t->src, sizeof(t->src) / sizeof(u32), > > - t->dst.protonum ^ seed); > > + return reciprocal_scale(hash, nf_nat_htable_size); > > } > > > > /* Is this tuple already taken? (not by us) */ > > @@ -187,28 +187,6 @@ same_src(const struct nf_conn *ct, > > t->src.u.all == tuple->src.u.all); > > } > > > > -static int nf_nat_bysource_cmp(struct rhashtable_compare_arg *arg, > > - const void *obj) > > -{ > > - const struct nf_nat_conn_key *key = arg->key; > > - const struct nf_conn *ct = obj; > > - > > - if (!same_src(ct, key->tuple) || > > - !net_eq(nf_ct_net(ct), key->net) || > > - !nf_ct_zone_equal(ct, key->zone, IP_CT_DIR_ORIGINAL)) > > - return 1; > > - > > - return 0; > > -} > > - > > -static struct rhashtable_params nf_nat_bysource_params = { > > - .head_offset = offsetof(struct nf_conn, nat_bysource), > > - .obj_hashfn = nf_nat_bysource_hash, > > - .obj_cmpfn = nf_nat_bysource_cmp, > > - .nelem_hint = 256, > > - .min_size = 1024, > > -}; > > - > > /* Only called for SRC manip */ > > static int > > find_appropriate_src(struct net *net, > > @@ -219,26 +197,22 @@ find_appropriate_src(struct net *net, > > struct nf_conntrack_tuple *result, > > const struct nf_nat_range *range) > > { > > + unsigned int h = hash_by_src(net, tuple); > > const struct nf_conn *ct; > > - struct nf_nat_conn_key key = { > > - .net = net, > > - .tuple = tuple, > > - .zone = zone > > - }; > > - struct rhlist_head *hl, *h; > > - > > - hl = rhltable_lookup(&nf_nat_bysource_table, &key, > > - nf_nat_bysource_params); > > > > - rhl_for_each_entry_rcu(ct, h, hl, nat_bysource) { > > - nf_ct_invert_tuplepr(result, > > - &ct->tuplehash[IP_CT_DIR_REPLY].tuple); > > - result->dst = tuple->dst; > > + hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) { > > + if (same_src(ct, tuple) && > > + net_eq(net, nf_ct_net(ct)) && > > + nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) { > > + /* Copy source part from reply tuple. */ > > + nf_ct_invert_tuplepr(result, > > + &ct->tuplehash[IP_CT_DIR_REPLY].tuple); > > + result->dst = tuple->dst; > > > > - if (in_range(l3proto, l4proto, result, range)) > > - return 1; > > + if (in_range(l3proto, l4proto, result, range)) > > + return 1; > > + } > > } > > - > > return 0; > > } > > > > @@ -411,6 +385,7 @@ nf_nat_setup_info(struct nf_conn *ct, > > const struct nf_nat_range *range, > > enum nf_nat_manip_type maniptype) > > { > > + struct net *net = nf_ct_net(ct); > > struct nf_conntrack_tuple curr_tuple, new_tuple; > > struct nf_conn_nat *nat; > > > > @@ -452,19 +427,16 @@ nf_nat_setup_info(struct nf_conn *ct, > > } > > > > if (maniptype == NF_NAT_MANIP_SRC) { > > - struct nf_nat_conn_key key = { > > - .net = nf_ct_net(ct), > > - .tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, > > - .zone = nf_ct_zone(ct), > > - }; > > - int err; > > - > > - err = rhltable_insert_key(&nf_nat_bysource_table, > > - &key, > > - &ct->nat_bysource, > > - nf_nat_bysource_params); > > - if (err) > > - return NF_DROP; > > + unsigned int srchash; > > + > > + srchash = hash_by_src(net, > > + &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); > > + spin_lock_bh(&nf_nat_lock); > > + /* nf_conntrack_alter_reply might re-allocate extension aera */ > > + nat = nfct_nat(ct); > > + hlist_add_head_rcu(&ct->nat_bysource, > > + &nf_nat_bysource[srchash]); > > + spin_unlock_bh(&nf_nat_lock); > > } > > > > /* It's done. */ > > @@ -578,9 +550,10 @@ static int nf_nat_proto_clean(struct nf_ > > * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack() > > * will delete entry from already-freed table. > > */ > > + spin_lock_bh(&nf_nat_lock); > > + hlist_del_rcu(&ct->nat_bysource); > > ct->status &= ~IPS_NAT_DONE_MASK; > > - rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource, > > - nf_nat_bysource_params); > > + spin_unlock_bh(&nf_nat_lock); > > > > /* don't delete conntrack. Although that would make things a lot > > * simpler, we'd end up flushing all conntracks on nat rmmod. > > @@ -710,8 +683,11 @@ static void nf_nat_cleanup_conntrack(str > > if (!nat) > > return; > > > > - rhltable_remove(&nf_nat_bysource_table, &ct->nat_bysource, > > - nf_nat_bysource_params); > > + NF_CT_ASSERT(ct->status & IPS_SRC_NAT_DONE); > > + > > + spin_lock_bh(&nf_nat_lock); > > + hlist_del_rcu(&ct->nat_bysource); > > + spin_unlock_bh(&nf_nat_lock); > > } > > > > static struct nf_ct_ext_type nat_extend __read_mostly = { > > @@ -846,13 +822,16 @@ static int __init nf_nat_init(void) > > { > > int ret; > > > > - ret = rhltable_init(&nf_nat_bysource_table, &nf_nat_bysource_params); > > - if (ret) > > - return ret; > > + /* Leave them the same for the moment. */ > > + nf_nat_htable_size = nf_conntrack_htable_size; > > + > > + nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0); > > + if (!nf_nat_bysource) > > + return -ENOMEM; > > > > ret = nf_ct_extend_register(&nat_extend); > > if (ret < 0) { > > - rhltable_destroy(&nf_nat_bysource_table); > > + nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size); > > printk(KERN_ERR "nf_nat_core: Unable to register extension\n"); > > return ret; > > } > > @@ -876,7 +855,7 @@ static int __init nf_nat_init(void) > > return 0; > > > > cleanup_extend: > > - rhltable_destroy(&nf_nat_bysource_table); > > + nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size); > > nf_ct_extend_unregister(&nat_extend); > > return ret; > > } > > @@ -896,8 +875,8 @@ static void __exit nf_nat_cleanup(void) > > > > for (i = 0; i < NFPROTO_NUMPROTO; i++) > > kfree(nf_nat_l4protos[i]); > > - > > - rhltable_destroy(&nf_nat_bysource_table); > > + synchronize_net(); > > + nf_ct_free_hashtable(nf_nat_bysource, nf_nat_htable_size); > > } > > > > MODULE_LICENSE("GPL"); > > > >
