From dd41d33f0b033885211a5d6f3ee19e73238aa9ee Mon Sep 17 00:00:00 2001 From: Jarno Rajahalme Date: Thu, 9 Feb 2017 11:22:00 -0800 Subject: [PATCH] openvswitch: Add force commit. Stateful network admission policy may allow connections to one direction and reject connections initiated in the other direction. After policy change it is possible that for a new connection an overlapping conntrack entry already exists, where the original direction of the existing connection is opposed to the new connection's initial packet. Most importantly, conntrack state relating to the current packet gets the "reply" designation based on whether the original direction tuple or the reply direction tuple matched. If this "directionality" is wrong w.r.t. to the stateful network admission policy it may happen that packets in neither direction are correctly admitted. This patch adds a new "force commit" option to the OVS conntrack action that checks the original direction of an existing conntrack entry. If that direction is opposed to the current packet, the existing conntrack entry is deleted and a new one is subsequently created in the correct direction. Signed-off-by: Jarno Rajahalme Acked-by: Pravin B Shelar Acked-by: Joe Stringer Signed-off-by: David S. Miller --- include/uapi/linux/openvswitch.h | 5 +++++ net/openvswitch/conntrack.c | 26 ++++++++++++++++++++++++-- 2 files changed, 29 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h index 90af8b8e10f8..7f41f7d0000f 100644 --- a/include/uapi/linux/openvswitch.h +++ b/include/uapi/linux/openvswitch.h @@ -674,6 +674,10 @@ struct ovs_action_hash { * @OVS_CT_ATTR_HELPER: variable length string defining conntrack ALG. * @OVS_CT_ATTR_NAT: Nested OVS_NAT_ATTR_* for performing L3 network address * translation (NAT) on the packet. + * @OVS_CT_ATTR_FORCE_COMMIT: Like %OVS_CT_ATTR_COMMIT, but instead of doing + * nothing if the connection is already committed will check that the current + * packet is in conntrack entry's original direction. If directionality does + * not match, will delete the existing conntrack entry and commit a new one. */ enum ovs_ct_attr { OVS_CT_ATTR_UNSPEC, @@ -684,6 +688,7 @@ enum ovs_ct_attr { OVS_CT_ATTR_HELPER, /* netlink helper to assist detection of related connections. */ OVS_CT_ATTR_NAT, /* Nested OVS_NAT_ATTR_* */ + OVS_CT_ATTR_FORCE_COMMIT, /* No argument */ __OVS_CT_ATTR_MAX }; diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c index bfd7606c8be1..8b15bab70583 100644 --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -65,6 +65,7 @@ struct ovs_conntrack_info { struct nf_conn *ct; u8 commit : 1; u8 nat : 3; /* enum ovs_ct_nat */ + u8 force : 1; u16 family; struct md_mark mark; struct md_labels labels; @@ -613,10 +614,13 @@ static bool skb_nfct_cached(struct net *net, */ if (!ct && key->ct.state & OVS_CS_F_TRACKED && !(key->ct.state & OVS_CS_F_INVALID) && - key->ct.zone == info->zone.id) + key->ct.zone == info->zone.id) { ct = ovs_ct_find_existing(net, &info->zone, info->family, skb, !!(key->ct.state & OVS_CS_F_NAT_MASK)); + if (ct) + nf_ct_get(skb, &ctinfo); + } if (!ct) return false; if (!net_eq(net, read_pnet(&ct->ct_net))) @@ -630,6 +634,18 @@ static bool skb_nfct_cached(struct net *net, if (help && rcu_access_pointer(help->helper) != info->helper) return false; } + /* Force conntrack entry direction to the current packet? */ + if (info->force && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) { + /* Delete the conntrack entry if confirmed, else just release + * the reference. + */ + if (nf_ct_is_confirmed(ct)) + nf_ct_delete(ct, 0, 0); + else + nf_conntrack_put(&ct->ct_general); + nf_ct_set(skb, NULL, 0); + return false; + } return true; } @@ -1207,6 +1223,7 @@ static int parse_nat(const struct nlattr *attr, static const struct ovs_ct_len_tbl ovs_ct_attr_lens[OVS_CT_ATTR_MAX + 1] = { [OVS_CT_ATTR_COMMIT] = { .minlen = 0, .maxlen = 0 }, + [OVS_CT_ATTR_FORCE_COMMIT] = { .minlen = 0, .maxlen = 0 }, [OVS_CT_ATTR_ZONE] = { .minlen = sizeof(u16), .maxlen = sizeof(u16) }, [OVS_CT_ATTR_MARK] = { .minlen = sizeof(struct md_mark), @@ -1246,6 +1263,9 @@ static int parse_ct(const struct nlattr *attr, struct ovs_conntrack_info *info, } switch (type) { + case OVS_CT_ATTR_FORCE_COMMIT: + info->force = true; + /* fall through. */ case OVS_CT_ATTR_COMMIT: info->commit = true; break; @@ -1472,7 +1492,9 @@ int ovs_ct_action_to_attr(const struct ovs_conntrack_info *ct_info, if (!start) return -EMSGSIZE; - if (ct_info->commit && nla_put_flag(skb, OVS_CT_ATTR_COMMIT)) + if (ct_info->commit && nla_put_flag(skb, ct_info->force + ? OVS_CT_ATTR_FORCE_COMMIT + : OVS_CT_ATTR_COMMIT)) return -EMSGSIZE; if (IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) && nla_put_u16(skb, OVS_CT_ATTR_ZONE, ct_info->zone.id)) -- 2.20.1