4.20-stable review patch. If anyone has any objections, please let me know.
------------------
From: Florian Westphal fw@strlen.de
commit df4a902509766897f7371fdfa4c3bf8bc321b55d upstream.
'lookup' is always followed by 'add'. Merge both and make the list-walk part of nf_conncount_add().
This also avoids one unneeded unlock/re-lock pair.
Extra care needs to be taken in count_tree, as we only hold rcu read lock, i.e. we can only insert to an existing tree node after acquiring its lock and making sure it has a nonzero count.
As a zero count should be rare, just fall back to insert_tree() (which acquires tree lock).
This issue and its solution were pointed out by Shawn Bohrer during patch review.
Reviewed-by: Shawn Bohrer sbohrer@cloudflare.com Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/net/netfilter/nf_conntrack_count.h | 18 --- net/netfilter/nf_conncount.c | 146 +++++++++++++---------------- net/netfilter/nft_connlimit.c | 14 -- 3 files changed, 72 insertions(+), 106 deletions(-)
--- a/include/net/netfilter/nf_conntrack_count.h +++ b/include/net/netfilter/nf_conntrack_count.h @@ -5,12 +5,6 @@
struct nf_conncount_data;
-enum nf_conncount_list_add { - NF_CONNCOUNT_ADDED, /* list add was ok */ - NF_CONNCOUNT_ERR, /* -ENOMEM, must drop skb */ - NF_CONNCOUNT_SKIP, /* list is already reclaimed by gc */ -}; - struct nf_conncount_list { spinlock_t list_lock; struct list_head head; /* connections with the same filtering key */ @@ -29,18 +23,12 @@ unsigned int nf_conncount_count(struct n const struct nf_conntrack_tuple *tuple, const struct nf_conntrack_zone *zone);
-void nf_conncount_lookup(struct net *net, struct nf_conncount_list *list, - const struct nf_conntrack_tuple *tuple, - const struct nf_conntrack_zone *zone, - bool *addit); +int nf_conncount_add(struct net *net, struct nf_conncount_list *list, + const struct nf_conntrack_tuple *tuple, + const struct nf_conntrack_zone *zone);
void nf_conncount_list_init(struct nf_conncount_list *list);
-enum nf_conncount_list_add -nf_conncount_add(struct nf_conncount_list *list, - const struct nf_conntrack_tuple *tuple, - const struct nf_conntrack_zone *zone); - bool nf_conncount_gc_list(struct net *net, struct nf_conncount_list *list);
--- a/net/netfilter/nf_conncount.c +++ b/net/netfilter/nf_conncount.c @@ -83,38 +83,6 @@ static int key_diff(const u32 *a, const return memcmp(a, b, klen * sizeof(u32)); }
-enum nf_conncount_list_add -nf_conncount_add(struct nf_conncount_list *list, - const struct nf_conntrack_tuple *tuple, - const struct nf_conntrack_zone *zone) -{ - struct nf_conncount_tuple *conn; - - if (WARN_ON_ONCE(list->count > INT_MAX)) - return NF_CONNCOUNT_ERR; - - conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC); - if (conn == NULL) - return NF_CONNCOUNT_ERR; - - conn->tuple = *tuple; - conn->zone = *zone; - conn->cpu = raw_smp_processor_id(); - conn->jiffies32 = (u32)jiffies; - conn->dead = false; - spin_lock_bh(&list->list_lock); - if (list->dead == true) { - kmem_cache_free(conncount_conn_cachep, conn); - spin_unlock_bh(&list->list_lock); - return NF_CONNCOUNT_SKIP; - } - list_add_tail(&conn->node, &list->head); - list->count++; - spin_unlock_bh(&list->list_lock); - return NF_CONNCOUNT_ADDED; -} -EXPORT_SYMBOL_GPL(nf_conncount_add); - static void __conn_free(struct rcu_head *h) { struct nf_conncount_tuple *conn; @@ -177,11 +145,10 @@ find_or_evict(struct net *net, struct nf return ERR_PTR(-EAGAIN); }
-void nf_conncount_lookup(struct net *net, - struct nf_conncount_list *list, - const struct nf_conntrack_tuple *tuple, - const struct nf_conntrack_zone *zone, - bool *addit) +static int __nf_conncount_add(struct net *net, + struct nf_conncount_list *list, + const struct nf_conntrack_tuple *tuple, + const struct nf_conntrack_zone *zone) { const struct nf_conntrack_tuple_hash *found; struct nf_conncount_tuple *conn, *conn_n; @@ -189,9 +156,6 @@ void nf_conncount_lookup(struct net *net unsigned int collect = 0; bool free_entry = false;
- /* best effort only */ - *addit = tuple ? true : false; - /* check the saved connections */ list_for_each_entry_safe(conn, conn_n, &list->head, node) { if (collect > CONNCOUNT_GC_MAX_NODES) @@ -201,21 +165,19 @@ void nf_conncount_lookup(struct net *net if (IS_ERR(found)) { /* Not found, but might be about to be confirmed */ if (PTR_ERR(found) == -EAGAIN) { - if (!tuple) - continue; - if (nf_ct_tuple_equal(&conn->tuple, tuple) && nf_ct_zone_id(&conn->zone, conn->zone.dir) == nf_ct_zone_id(zone, zone->dir)) - *addit = false; - } else if (PTR_ERR(found) == -ENOENT) + return 0; /* already exists */ + } else { collect++; + } continue; }
found_ct = nf_ct_tuplehash_to_ctrack(found);
- if (tuple && nf_ct_tuple_equal(&conn->tuple, tuple) && + if (nf_ct_tuple_equal(&conn->tuple, tuple) && nf_ct_zone_equal(found_ct, zone, zone->dir)) { /* * We should not see tuples twice unless someone hooks @@ -223,7 +185,8 @@ void nf_conncount_lookup(struct net *net * * Attempt to avoid a re-add in this case. */ - *addit = false; + nf_ct_put(found_ct); + return 0; } else if (already_closed(found_ct)) { /* * we do not care about connections which are @@ -237,8 +200,38 @@ void nf_conncount_lookup(struct net *net
nf_ct_put(found_ct); } + + if (WARN_ON_ONCE(list->count > INT_MAX)) + return -EOVERFLOW; + + conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC); + if (conn == NULL) + return -ENOMEM; + + conn->tuple = *tuple; + conn->zone = *zone; + conn->cpu = raw_smp_processor_id(); + conn->jiffies32 = (u32)jiffies; + list_add_tail(&conn->node, &list->head); + list->count++; + return 0; +} + +int nf_conncount_add(struct net *net, + struct nf_conncount_list *list, + const struct nf_conntrack_tuple *tuple, + const struct nf_conntrack_zone *zone) +{ + int ret; + + /* check the saved connections */ + spin_lock_bh(&list->list_lock); + ret = __nf_conncount_add(net, list, tuple, zone); + spin_unlock_bh(&list->list_lock); + + return ret; } -EXPORT_SYMBOL_GPL(nf_conncount_lookup); +EXPORT_SYMBOL_GPL(nf_conncount_add);
void nf_conncount_list_init(struct nf_conncount_list *list) { @@ -339,13 +332,11 @@ insert_tree(struct net *net, const struct nf_conntrack_tuple *tuple, const struct nf_conntrack_zone *zone) { - enum nf_conncount_list_add ret; struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES]; struct rb_node **rbnode, *parent; struct nf_conncount_rb *rbconn; struct nf_conncount_tuple *conn; unsigned int count = 0, gc_count = 0; - bool node_found = false; bool do_gc = true;
spin_lock_bh(&nf_conncount_locks[hash]); @@ -363,20 +354,15 @@ restart: } else if (diff > 0) { rbnode = &((*rbnode)->rb_right); } else { - /* unlikely: other cpu added node already */ - node_found = true; - ret = nf_conncount_add(&rbconn->list, tuple, zone); - if (ret == NF_CONNCOUNT_ERR) { + int ret; + + ret = nf_conncount_add(net, &rbconn->list, tuple, zone); + if (ret) count = 0; /* hotdrop */ - } else if (ret == NF_CONNCOUNT_ADDED) { + else count = rbconn->list.count; - } else { - /* NF_CONNCOUNT_SKIP, rbconn is already - * reclaimed by gc, insert a new tree node - */ - node_found = false; - } - break; + tree_nodes_free(root, gc_nodes, gc_count); + goto out_unlock; }
if (gc_count >= ARRAY_SIZE(gc_nodes)) @@ -394,9 +380,6 @@ restart: goto restart; }
- if (node_found) - goto out_unlock; - /* expected case: match, insert new node */ rbconn = kmem_cache_alloc(conncount_rb_cachep, GFP_ATOMIC); if (rbconn == NULL) @@ -431,7 +414,6 @@ count_tree(struct net *net, const struct nf_conntrack_tuple *tuple, const struct nf_conntrack_zone *zone) { - enum nf_conncount_list_add ret; struct rb_root *root; struct rb_node *parent; struct nf_conncount_rb *rbconn; @@ -444,7 +426,6 @@ count_tree(struct net *net, parent = rcu_dereference_raw(root->rb_node); while (parent) { int diff; - bool addit;
rbconn = rb_entry(parent, struct nf_conncount_rb, node);
@@ -454,24 +435,29 @@ count_tree(struct net *net, } else if (diff > 0) { parent = rcu_dereference_raw(parent->rb_right); } else { - /* same source network -> be counted! */ - nf_conncount_lookup(net, &rbconn->list, tuple, zone, - &addit); + int ret;
- if (!addit) + if (!tuple) { + nf_conncount_gc_list(net, &rbconn->list); return rbconn->list.count; + }
- ret = nf_conncount_add(&rbconn->list, tuple, zone); - if (ret == NF_CONNCOUNT_ERR) { - return 0; /* hotdrop */ - } else if (ret == NF_CONNCOUNT_ADDED) { - return rbconn->list.count; - } else { - /* NF_CONNCOUNT_SKIP, rbconn is already - * reclaimed by gc, insert a new tree node - */ + spin_lock_bh(&rbconn->list.list_lock); + /* Node might be about to be free'd. + * We need to defer to insert_tree() in this case. + */ + if (rbconn->list.count == 0) { + spin_unlock_bh(&rbconn->list.list_lock); break; } + + /* same source network -> be counted! */ + ret = __nf_conncount_add(net, &rbconn->list, tuple, zone); + spin_unlock_bh(&rbconn->list.list_lock); + if (ret) + return 0; /* hotdrop */ + else + return rbconn->list.count; } }
--- a/net/netfilter/nft_connlimit.c +++ b/net/netfilter/nft_connlimit.c @@ -30,7 +30,6 @@ static inline void nft_connlimit_do_eval enum ip_conntrack_info ctinfo; const struct nf_conn *ct; unsigned int count; - bool addit;
tuple_ptr = &tuple;
@@ -44,19 +43,12 @@ static inline void nft_connlimit_do_eval return; }
- nf_conncount_lookup(nft_net(pkt), &priv->list, tuple_ptr, zone, - &addit); - count = priv->list.count; - - if (!addit) - goto out; - - if (nf_conncount_add(&priv->list, tuple_ptr, zone) == NF_CONNCOUNT_ERR) { + if (nf_conncount_add(nft_net(pkt), &priv->list, tuple_ptr, zone)) { regs->verdict.code = NF_DROP; return; } - count++; -out: + + count = priv->list.count;
if ((count > priv->limit) ^ priv->invert) { regs->verdict.code = NFT_BREAK;