A malicious actor behind one bridge port may spam the kernel with OGMs with a random source MAC address, each of which will create a BLA claim, each of which is a dynamic allocation in the kernel. This will at some point exhaust the available memory.
Mitigate this by maintaining a per meshif count of those automatically generated entries in orig_learned, and a limit in orig_max_learned. If the limit is hit new entries are not learned anymore. For backwards compatibility, the default setting of 0 disables the limit. Signed-off-by: Sven Eckelmann <[email protected]> --- include/uapi/linux/batman_adv.h | 6 ++++++ net/batman-adv/bridge_loop_avoidance.c | 11 +++++++++++ net/batman-adv/mesh-interface.c | 3 +++ net/batman-adv/netlink.c | 10 ++++++++++ net/batman-adv/types.h | 6 ++++++ 5 files changed, 36 insertions(+) diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h index 4188d83c..65d1c0eb 100644 --- a/include/uapi/linux/batman_adv.h +++ b/include/uapi/linux/batman_adv.h @@ -505,6 +505,12 @@ enum batadv_nl_attrs { */ BATADV_ATTR_BLA_BACKBONE_MAX_LEARNED, + /** + * @BATADV_ATTR_BLA_CLAIM_MAX_LEARNED: defines the maximum number of BLA claim + * which can be learned in parallel + */ + BATADV_ATTR_BLA_CLAIM_MAX_LEARNED, + /* add attributes above here, update the policy in netlink.c */ /** diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index 8bb8dec6..f39b02f9 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -320,6 +320,7 @@ batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw) hlist_del_rcu(&claim->hash_entry); batadv_claim_put(claim); + atomic_dec(&backbone_gw->bat_priv->bla_claim_learned); } spin_unlock_bh(list_lock); } @@ -700,7 +701,9 @@ static void batadv_bla_add_claim(struct batadv_priv *bat_priv, struct batadv_bla_backbone_gw *old_backbone_gw; struct batadv_bla_claim *claim; struct batadv_bla_claim search_claim; + u32 bla_claim_max_learned; bool remove_crc = false; + int bla_claim_learned; int hash_added; ether_addr_copy(search_claim.addr, mac); @@ -709,6 +712,11 @@ static void batadv_bla_add_claim(struct batadv_priv *bat_priv, /* create a new claim entry if it does not exist yet. */ if (!claim) { + bla_claim_max_learned = READ_ONCE(bat_priv->bla_claim_max_learned); + bla_claim_learned = atomic_read(&bat_priv->bla_claim_learned); + if (bla_claim_max_learned && bla_claim_learned >= bla_claim_max_learned) + return; + claim = kzalloc_obj(*claim, GFP_ATOMIC); if (!claim) return; @@ -721,6 +729,8 @@ static void batadv_bla_add_claim(struct batadv_priv *bat_priv, claim->backbone_gw = backbone_gw; kref_init(&claim->refcount); + atomic_inc(&bat_priv->bla_claim_learned); + batadv_dbg(BATADV_DBG_BLA, bat_priv, "%s(): adding new entry %pM, vid %d to hash ...\n", __func__, mac, batadv_print_vid(vid)); @@ -735,6 +745,7 @@ static void batadv_bla_add_claim(struct batadv_priv *bat_priv, /* only local changes happened. */ batadv_backbone_gw_put(backbone_gw); kfree(claim); + atomic_dec(&bat_priv->bla_claim_learned); return; } } else { diff --git a/net/batman-adv/mesh-interface.c b/net/batman-adv/mesh-interface.c index 1594a2d6..8fd47cef 100644 --- a/net/batman-adv/mesh-interface.c +++ b/net/batman-adv/mesh-interface.c @@ -793,6 +793,9 @@ static int batadv_meshif_init_late(struct net_device *dev) atomic_set(&bat_priv->bla_backbone_learned, 0); WRITE_ONCE(bat_priv->bla_backbone_max_learned, 0); + + atomic_set(&bat_priv->bla_claim_learned, 0); + WRITE_ONCE(bat_priv->bla_claim_max_learned, 0); #endif atomic_set(&bat_priv->tp_num, 0); diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c index 5d4bccdc..8cafbac5 100644 --- a/net/batman-adv/netlink.c +++ b/net/batman-adv/netlink.c @@ -151,6 +151,7 @@ static const struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = { [BATADV_ATTR_ORIG_MAX_LEARNED] = { .type = NLA_U32 }, [BATADV_ATTR_DAT_MAX_LEARNED] = { .type = NLA_U32 }, [BATADV_ATTR_BLA_BACKBONE_MAX_LEARNED] = { .type = NLA_U32 }, + [BATADV_ATTR_BLA_CLAIM_MAX_LEARNED] = { .type = NLA_U32 }, }; /** @@ -298,6 +299,10 @@ static int batadv_netlink_mesh_fill(struct sk_buff *msg, if (nla_put_u32(msg, BATADV_ATTR_BLA_BACKBONE_MAX_LEARNED, READ_ONCE(bat_priv->bla_backbone_max_learned))) goto nla_put_failure; + + if (nla_put_u32(msg, BATADV_ATTR_BLA_CLAIM_MAX_LEARNED, + READ_ONCE(bat_priv->bla_claim_max_learned))) + goto nla_put_failure; #endif /* CONFIG_BATMAN_ADV_BLA */ #ifdef CONFIG_BATMAN_ADV_DAT @@ -493,6 +498,11 @@ static int batadv_netlink_set_mesh(struct sk_buff *skb, struct genl_info *info) WRITE_ONCE(bat_priv->bla_backbone_max_learned, nla_get_u32(info->attrs[BATADV_ATTR_BLA_BACKBONE_MAX_LEARNED])); } + + if (info->attrs[BATADV_ATTR_BLA_CLAIM_MAX_LEARNED]) { + WRITE_ONCE(bat_priv->bla_claim_max_learned, + nla_get_u32(info->attrs[BATADV_ATTR_BLA_CLAIM_MAX_LEARNED])); + } #endif /* CONFIG_BATMAN_ADV_BLA */ #ifdef CONFIG_BATMAN_ADV_DAT diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index c091b19e..ddd9f1e0 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -1662,6 +1662,12 @@ struct batadv_priv { /** @bla_backbone_learned: current number of learned backbone_gw entries */ atomic_t bla_backbone_learned; + /** @bla_claim_max_learned: Maximum number of claim */ + u32 bla_claim_max_learned; + + /** @bla_claim_learned: current number of learned claim entries */ + atomic_t bla_claim_learned; + /** @bla: bridge loop avoidance data */ struct batadv_priv_bla bla; #endif -- 2.47.3
