With this patch IGMP or MLD reports are only forwarded to the selected IGMP/MLD querier as RFC4541 suggests. This is necessary to avoid multicast packet loss in bridged scenarios later:
An IGMPv2/MLDv1 querier does not actively join the multicast group the reports are sent to. Because of this, this leads to snooping bridges/switches not being able to learn of multicast listeners in the mesh and wrongly shutting down ports for multicast traffic to the mesh. --- net/batman-adv/multicast.c | 240 ++++++++++++++++++++++++++++++++++++++- net/batman-adv/multicast.h | 8 ++ net/batman-adv/soft-interface.c | 8 ++ net/batman-adv/types.h | 14 +++ 4 files changed, 267 insertions(+), 3 deletions(-)
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c index b24e4bb..bafc323 100644 --- a/net/batman-adv/multicast.c +++ b/net/batman-adv/multicast.c @@ -247,10 +247,76 @@ out: }
/** + * batadv_mcast_is_report_ipv4 - check for IGMP reports (and queries) + * @bat_priv: the bat priv with all the soft interface information + * @skb: the ethernet frame destined for the mesh + * @orig: if IGMP report: to be set to the querier to forward the skb to + * + * Checks whether the given frame is an IGMP report and if so sets the + * orig pointer to the originator of the selected IGMP querier if one exists + * and returns true. Otherwise returns false. + * + * If the packet is a general IGMP query instead then we delete the memorized, + * foreign IGMP querier (if one exists): We became the selected querier and + * therefore do not need to forward reports into the mesh. + * + * This call might reallocate skb data. + */ +static bool batadv_mcast_is_report_ipv4(struct batadv_priv *bat_priv, + struct sk_buff *skb, + struct batadv_orig_node **orig) +{ + struct batadv_mcast_querier_state *querier; + struct batadv_orig_node *orig_node; + + if (!ip_mc_check_igmp(skb, NULL)) + return false; + + querier = &bat_priv->mcast.querier_ipv4; + + switch (igmp_hdr(skb)->type) { + case IGMP_HOST_MEMBERSHIP_REPORT: + case IGMPV2_HOST_MEMBERSHIP_REPORT: + case IGMPV3_HOST_MEMBERSHIP_REPORT: + rcu_read_lock(); + orig_node = rcu_dereference(querier->orig); + if (orig_node && atomic_inc_not_zero(&orig_node->refcount)) { + /* TODO: include multicast routers via MRD (RFC4286) */ + batadv_dbg(BATADV_DBG_MCAST, bat_priv, + "Redirecting IGMP Report to %pM\n", + orig_node->orig); + *orig = orig_node; + } + rcu_read_unlock(); + + return true; + case IGMP_HOST_MEMBERSHIP_QUERY: + /* RFC4541, section 2.1.1.1.b) says: + * ignore general queries from 0.0.0.0 + */ + if (!ip_hdr(skb)->saddr || igmp_hdr(skb)->group) + break; + + spin_lock_bh(&querier->orig_lock); + orig_node = rcu_dereference(querier->orig); + if (orig_node) + rcu_assign_pointer(querier->orig, NULL); + spin_unlock_bh(&querier->orig_lock); + + batadv_dbg(BATADV_DBG_MCAST, bat_priv, + "Snooped own IGMP Query\n"); + break; + } + + return false; +} + +/** * batadv_mcast_forw_mode_check_ipv4 - check for optimized forwarding potential * @bat_priv: the bat priv with all the soft interface information * @skb: the IPv4 packet to check * @is_unsnoopable: stores whether the destination is snoopable + * @orig: for IGMP reports: to be set to the querier to forward the skb to * * Checks whether the given IPv4 packet has the potential to be forwarded with a * mode more optimal than classic flooding. @@ -260,7 +326,8 @@ out: */ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv, struct sk_buff *skb, - bool *is_unsnoopable) + bool *is_unsnoopable, + struct batadv_orig_node **orig) { struct iphdr *iphdr;
@@ -268,6 +335,9 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv, if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*iphdr))) return -ENOMEM;
+ if (batadv_mcast_is_report_ipv4(bat_priv, skb, orig)) + return 0; + iphdr = ip_hdr(skb);
/* TODO: Implement Multicast Router Discovery (RFC4286), @@ -285,10 +355,71 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv, }
/** + * batadv_mcast_is_report_ipv6 - check for MLD reports (and queries) + * @bat_priv: the bat priv with all the soft interface information + * @skb: the ethernet frame destined for the mesh + * @orig: if MLD report: to be set to the querier to forward the skb to + * + * Checks whether the given frame is an MLD report and if so sets the + * orig pointer to the originator of the selected MLD querier if one exists + * and returns true. Otherwise returns false. + * + * If the packet is a general MLD query instead then we delete the memorized, + * foreign MLD querier (if one exists): We became the selected querier and + * therefore do not need to forward reports into the mesh. + * + * This call might reallocate skb data. + */ +static bool batadv_mcast_is_report_ipv6(struct batadv_priv *bat_priv, + struct sk_buff *skb, + struct batadv_orig_node **orig) +{ + struct mld_msg *mld; + struct batadv_mcast_querier_state *querier; + struct batadv_orig_node *orig_node; + + if (!ipv6_mc_check_mld(skb, NULL)) + return false; + + querier = &bat_priv->mcast.querier_ipv6; + mld = (struct mld_msg *)icmp6_hdr(skb); + + switch (mld->mld_type) { + case ICMPV6_MGM_REPORT: + case ICMPV6_MLD2_REPORT: + rcu_read_lock(); + orig_node = rcu_dereference(querier->orig); + if (orig_node && atomic_inc_not_zero(&orig_node->refcount)) { + /* TODO: include multicast routers via MRD (RFC4286) */ + batadv_dbg(BATADV_DBG_MCAST, bat_priv, + "Redirecting MLD Report to %pM\n", + orig_node->orig); + *orig = orig_node; + } + rcu_read_unlock(); + + return true; + case ICMPV6_MGM_QUERY: + spin_lock_bh(&querier->orig_lock); + orig_node = rcu_dereference(querier->orig); + if (orig_node) + rcu_assign_pointer(querier->orig, NULL); + spin_unlock_bh(&querier->orig_lock); + + batadv_dbg(BATADV_DBG_MCAST, bat_priv, + "Snooped own MLD Query\n"); + break; + } + + return false; +} + +/** * batadv_mcast_forw_mode_check_ipv6 - check for optimized forwarding potential * @bat_priv: the bat priv with all the soft interface information * @skb: the IPv6 packet to check * @is_unsnoopable: stores whether the destination is snoopable + * @orig: for MLD reports: to be set to the querier to forward the skb to * * Checks whether the given IPv6 packet has the potential to be forwarded with a * mode more optimal than classic flooding. @@ -298,7 +429,8 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv, */ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv, struct sk_buff *skb, - bool *is_unsnoopable) + bool *is_unsnoopable, + struct batadv_orig_node **orig) { struct ipv6hdr *ip6hdr;
@@ -306,6 +438,9 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv, if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*ip6hdr))) return -ENOMEM;
+ if (batadv_mcast_is_report_ipv6(bat_priv, skb, orig)) + return 0; + ip6hdr = ipv6_hdr(skb);
/* TODO: Implement Multicast Router Discovery (RFC4286), @@ -521,12 +656,16 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb, bool is_unsnoopable = false; struct ethhdr *ethhdr;
- ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable); + ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable, + orig); if (ret == -ENOMEM) return BATADV_FORW_NONE; else if (ret < 0) return BATADV_FORW_ALL;
+ if (*orig) + return BATADV_FORW_SINGLE; + ethhdr = eth_hdr(skb);
tt_count = batadv_tt_global_hash_count(bat_priv, ethhdr->h_dest, @@ -558,6 +697,101 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb, }
/** + * batadv_mcast_snoop_query_ipv4 - snoop for the selected MLD querier + * @skb: the unencapsulated ethernet frame coming from the mesh + * @orig_node: the originator this frame came from + * + * Checks whether the given frame is a general IGMP query from the selected + * querier and if so memorizes the originator this frame came from. + */ +static void batadv_mcast_snoop_query_ipv4(struct sk_buff *skb, + struct batadv_orig_node *orig_node) +{ + struct batadv_mcast_querier_state *querier; + + if (!ip_mc_check_igmp(skb, NULL); + return; + + /* we are only interested in general queries (group == 0.0.0.0) */ + if (igmp_hdr(skb)->type != IGMP_HOST_MEMBERSHIP_QUERY || + igmp_hdr(skb)->group) + return; + + /* RFC4541, section 2.1.1.1.b) says: ignore queries from 0.0.0.0 */ + if (!ip_hdr(skb)->saddr) + return; + + querier = &orig_node->bat_priv->mcast.querier_ipv4; + + spin_lock_bh(&querier->orig_lock); + rcu_assign_pointer(querier->orig, orig_node); + spin_unlock_bh(&querier->orig_lock); + + batadv_dbg(BATADV_DBG_MCAST, orig_node->bat_priv, + "Snooped IGMP Query from originator %pM\n", orig_node->orig); +} + +/** + * batadv_mcast_snoop_query_ipv6 - snoop for the selected MLD querier + * @skb: the unencapsulated ethernet frame coming from the mesh + * @orig_node: the originator this frame came from + * + * Checks whether the given frame is a general MLD query from the selected + * querier and if so memorizes the originator this frame came from. + */ +static void batadv_mcast_snoop_query_ipv6(struct sk_buff *skb, + struct batadv_orig_node *orig_node) +{ + struct mld_msg *mld; + struct batadv_mcast_querier_state *querier; + + if (!ipv6_mc_check_mld(skb, NULL)) + return; + + mld = (struct mld_msg *)icmp6_hdr(skb); + + /* we are only interested in general queries (mca == ::) */ + if (mld->mld_type != ICMPV6_MGM_QUERY || + !ipv6_addr_any(&mld->mld_mca)) + return; + + querier = &orig_node->bat_priv->mcast.querier_ipv6; + + spin_lock_bh(&querier->orig_lock); + rcu_assign_pointer(querier->orig, orig_node); + spin_unlock_bh(&querier->orig_lock); + + batadv_dbg(BATADV_DBG_MCAST, orig_node->bat_priv, + "Snooped MLD Query from originator %pM\n", orig_node->orig); +} + +/** + * batadv_mcast_snoop_query - snoop the selected IGMP/MLD querier + * @skb: the unencapsulated ethernet frame coming from the mesh + * @orig_node: the originator this frame came from + * + * Checks whether the given frame is a general IGMP or MLD query + * from the selected querier and if so memorizes the originator + * this frame came from. + * + * This call might reallocate skb data. + */ +void batadv_mcast_snoop_query(struct sk_buff *skb, + struct batadv_orig_node *orig_node) +{ + struct ethhdr *ethhdr = eth_hdr(skb); + + switch (ntohs(ethhdr->h_proto)) { + case ETH_P_IP: + batadv_mcast_snoop_query_ipv4(skb, orig_node); + break; + case ETH_P_IPV6: + batadv_mcast_snoop_query_ipv6(skb, orig_node); + break; + } +} + +/** * batadv_mcast_want_unsnoop_update - update unsnoop counter and list * @bat_priv: the bat priv with all the soft interface information * @orig: the orig_node which multicast state might have changed of diff --git a/net/batman-adv/multicast.h b/net/batman-adv/multicast.h index 3a44ebd..3727beb 100644 --- a/net/batman-adv/multicast.h +++ b/net/batman-adv/multicast.h @@ -40,6 +40,9 @@ enum batadv_forw_mode batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb, struct batadv_orig_node **mcast_single_orig);
+void batadv_mcast_snoop_query(struct sk_buff *skb, + struct batadv_orig_node *orig_node); + void batadv_mcast_init(struct batadv_priv *bat_priv);
void batadv_mcast_free(struct batadv_priv *bat_priv); @@ -59,6 +62,11 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb, return BATADV_FORW_ALL; }
+static inline void batadv_mcast_snoop_query(struct sk_buff *skb, + struct batadv_orig_node *orig_node) +{ +} + static inline int batadv_mcast_init(struct batadv_priv *bat_priv) { return 0; diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 5ec31d7..52b5737 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -428,6 +428,9 @@ void batadv_interface_rx(struct net_device *soft_iface, skb->mark &= ~bat_priv->isolation_mark_mask; skb->mark |= bat_priv->isolation_mark; } + + if (orig_node) + batadv_mcast_snoop_query(skb, orig_node); } else if (batadv_is_ap_isolated(bat_priv, ethhdr->h_source, ethhdr->h_dest, vid)) { goto dropped; @@ -738,6 +741,11 @@ static int batadv_softif_init_late(struct net_device *dev) atomic_set(&bat_priv->distributed_arp_table, 1); #endif #ifdef CONFIG_BATMAN_ADV_MCAST + rcu_assign_pointer(bat_priv->mcast.querier_ipv4.orig, NULL); + spin_lock_init(&bat_priv->mcast.querier_ipv4.orig_lock); + rcu_assign_pointer(bat_priv->mcast.querier_ipv6.orig, NULL); + spin_lock_init(&bat_priv->mcast.querier_ipv6.orig_lock); + bat_priv->mcast.flags = BATADV_NO_FLAGS; atomic_set(&bat_priv->multicast_mode, 1); atomic_set(&bat_priv->mcast.num_disabled, 0); diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 9398c3f..a0f5bf8 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -623,12 +623,24 @@ struct batadv_priv_dat {
#ifdef CONFIG_BATMAN_ADV_MCAST /** + * struct batadv_mcast_querier_state - IGMP/MLD querier state when bridged + * @orig: node on which the selected querier resides + * @orig_lock: protects updates of the selected querier in 'orig' + */ +struct batadv_mcast_querier_state { + struct batadv_orig_node __rcu *orig; /* rcu protected pointer */ + spinlock_t orig_lock; /* protects updates of orig */ +}; + +/** * struct batadv_priv_mcast - per mesh interface mcast data * @mla_list: list of multicast addresses we are currently announcing via TT * @want_all_unsnoopables_list: a list of orig_nodes wanting all unsnoopable * multicast traffic * @want_all_ipv4_list: a list of orig_nodes wanting all IPv4 multicast traffic * @want_all_ipv6_list: a list of orig_nodes wanting all IPv6 multicast traffic + * @querier_ipv4: the current state of an IGMP querier in the mesh + * @querier_ipv6: the current state of an MLD querier in the mesh * @flags: the flags we have last sent in our mcast tvlv * @enabled: whether the multicast tvlv is currently enabled * @num_disabled: number of nodes that have no mcast tvlv @@ -643,6 +655,8 @@ struct batadv_priv_mcast { struct hlist_head want_all_unsnoopables_list; struct hlist_head want_all_ipv4_list; struct hlist_head want_all_ipv6_list; + struct batadv_mcast_querier_state querier_ipv4; + struct batadv_mcast_querier_state querier_ipv6; uint8_t flags; bool enabled; atomic_t num_disabled;