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.
Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue --- net/batman-adv/main.h | 4 +- net/batman-adv/multicast.c | 257 ++++++++++++++++++++++++++++++++++++++- net/batman-adv/multicast.h | 8 ++ net/batman-adv/soft-interface.c | 11 ++ net/batman-adv/types.h | 14 +++ 5 files changed, 287 insertions(+), 7 deletions(-)
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h index 41d27c7..2832cf9 100644 --- a/net/batman-adv/main.h +++ b/net/batman-adv/main.h @@ -219,6 +219,7 @@ __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr); * @BATADV_DBG_BLA: bridge loop avoidance messages * @BATADV_DBG_DAT: ARP snooping and DAT related messages * @BATADV_DBG_NC: network coding related messages + * @BATADV_DBG_MCAST: multicast related messages * @BATADV_DBG_ALL: the union of all the above log levels */ enum batadv_dbg_level { @@ -228,7 +229,8 @@ enum batadv_dbg_level { BATADV_DBG_BLA = BIT(3), BATADV_DBG_DAT = BIT(4), BATADV_DBG_NC = BIT(5), - BATADV_DBG_ALL = 63, + BATADV_DBG_MCAST = BIT(6), + BATADV_DBG_ALL = 127, };
#ifdef CONFIG_BATMAN_ADV_DEBUG diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c index 7aa480b..72d561c 100644 --- a/net/batman-adv/multicast.c +++ b/net/batman-adv/multicast.c @@ -24,6 +24,7 @@ #include <linux/etherdevice.h> #include <linux/fs.h> #include <linux/if_ether.h> +#include <linux/igmp.h> #include <linux/in6.h> #include <linux/in.h> #include <linux/ip.h> @@ -40,6 +41,7 @@ #include <linux/types.h> #include <net/addrconf.h> #include <net/ipv6.h> +#include <net/mld.h>
#include "packet.h" #include "translation-table.h" @@ -270,10 +272,76 @@ 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) < 0) + 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. @@ -283,7 +351,8 @@ 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;
@@ -291,6 +360,9 @@ 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), @@ -307,11 +379,73 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv, return 0; }
+#if IS_ENABLED(CONFIG_IPV6) +/** + * 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) < 0) + 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. @@ -321,7 +455,8 @@ 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;
@@ -329,6 +464,9 @@ 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), @@ -345,6 +483,7 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
return 0; } +#endif
/** * batadv_mcast_forw_mode_check - check for optimized forwarding potential @@ -360,7 +499,8 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv, */ static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv, struct sk_buff *skb, - bool *is_unsnoopable) + bool *is_unsnoopable, + struct batadv_orig_node **orig) { struct ethhdr *ethhdr = eth_hdr(skb);
@@ -373,10 +513,12 @@ static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv, switch (ntohs(ethhdr->h_proto)) { case ETH_P_IP: return batadv_mcast_forw_mode_check_ipv4(bat_priv, skb, - is_unsnoopable); + is_unsnoopable, orig); +#if IS_ENABLED(CONFIG_IPV6) case ETH_P_IPV6: return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb, - is_unsnoopable); + is_unsnoopable, orig); +#endif default: return -EINVAL; } @@ -544,12 +686,16 @@ 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, @@ -581,6 +727,105 @@ 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) < 0) + 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); +} + +#if IS_ENABLED(CONFIG_IPV6) +/** + * 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) < 0) + 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); +} +#endif + +/** + * 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; +#if IS_ENABLED(CONFIG_IPV6) + case ETH_P_IPV6: + batadv_mcast_snoop_query_ipv6(skb, orig_node); + break; +#endif + } +} + +/** * 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 beb6e56..fb61db9 100644 --- a/net/batman-adv/multicast.h +++ b/net/batman-adv/multicast.h @@ -46,6 +46,9 @@ 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); @@ -65,6 +68,11 @@ 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 c002961..0a8c2ae 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -206,6 +206,8 @@ static int batadv_interface_tx(struct sk_buff *skb, if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE) goto dropped;
+ skb_set_network_header(skb, ETH_HLEN); + soft_iface->trans_start = jiffies; vid = batadv_get_vid(skb, 0); ethhdr = eth_hdr(skb); @@ -396,6 +398,7 @@ void batadv_interface_rx(struct net_device *soft_iface,
skb_pull_rcsum(skb, hdr_size); skb_reset_mac_header(skb); + skb_set_network_header(skb, ETH_HLEN);
/* clean the netfilter state now that the batman-adv header has been * removed @@ -458,6 +461,9 @@ 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; @@ -768,6 +774,11 @@ 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 67d6348..3a5365f 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -640,12 +640,24 @@ 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 @@ -660,6 +672,8 @@ 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;