// SPDX-License-Identifier: GPL-2.0 /* Copyright (C) B.A.T.M.A.N. contributors: * * Marek Lindner */ #include "gateway_client.h" #include "main.h" #include <linux/atomic.h> #include <linux/byteorder/generic.h> #include <linux/errno.h> #include <linux/etherdevice.h> #include <linux/gfp.h> #include <linux/if_ether.h> #include <linux/if_vlan.h> #include <linux/in.h> #include <linux/ip.h> #include <linux/ipv6.h> #include <linux/kernel.h> #include <linux/kref.h> #include <linux/list.h> #include <linux/lockdep.h> #include <linux/netdevice.h> #include <linux/netlink.h> #include <linux/rculist.h> #include <linux/rcupdate.h> #include <linux/skbuff.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/stddef.h> #include <linux/udp.h> #include <net/sock.h> #include <uapi/linux/batadv_packet.h> #include <uapi/linux/batman_adv.h> #include "hard-interface.h" #include "log.h" #include "netlink.h" #include "originator.h" #include "routing.h" #include "soft-interface.h" #include "translation-table.h" /* These are the offsets of the "hw type" and "hw address length" in the dhcp * packet starting at the beginning of the dhcp header */ #define BATADV_DHCP_HTYPE_OFFSET 1 #define BATADV_DHCP_HLEN_OFFSET 2 /* Value of htype representing Ethernet */ #define BATADV_DHCP_HTYPE_ETHERNET 0x01 /* This is the offset of the "chaddr" field in the dhcp packet starting at the * beginning of the dhcp header */ #define BATADV_DHCP_CHADDR_OFFSET 28 /** * batadv_gw_node_release() - release gw_node from lists and queue for free * after rcu grace period * @ref: kref pointer of the gw_node */ static void batadv_gw_node_release(struct kref *ref) { struct batadv_gw_node *gw_node; gw_node = container_of(ref, struct batadv_gw_node, refcount); batadv_orig_node_put(gw_node->orig_node); kfree_rcu(gw_node, rcu); } /** * batadv_gw_node_put() - decrement the gw_node refcounter and possibly release * it * @gw_node: gateway node to free */ void batadv_gw_node_put(struct batadv_gw_node *gw_node) { kref_put(&gw_node->refcount, batadv_gw_node_release); } /** * batadv_gw_get_selected_gw_node() - Get currently selected gateway * @bat_priv: the bat priv with all the soft interface information * * Return: selected gateway (with increased refcnt), NULL on errors */ struct batadv_gw_node * batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv) { struct batadv_gw_node *gw_node; rcu_read_lock(); gw_node = rcu_dereference(bat_priv->gw.curr_gw); if (!gw_node) goto out; if (!kref_get_unless_zero(&gw_node->refcount)) gw_node = NULL; out: rcu_read_unlock(); return gw_node; } /** * batadv_gw_get_selected_orig() - Get originator of currently selected gateway * @bat_priv: the bat priv with all the soft interface information * * Return: orig_node of selected gateway (with increased refcnt), NULL on errors */ struct batadv_orig_node * batadv_gw_get_selected_orig(struct batadv_priv *bat_priv) { struct batadv_gw_node *gw_node; struct batadv_orig_node *orig_node = NULL; gw_node = batadv_gw_get_selected_gw_node(bat_priv); if (!gw_node) goto out; rcu_read_lock(); orig_node = gw_node->orig_node; if (!orig_node) goto unlock; if (!kref_get_unless_zero(&orig_node->refcount)) orig_node = NULL; unlock: rcu_read_unlock(); out: if (gw_node) batadv_gw_node_put(gw_node); return orig_node; } static void batadv_gw_select(struct batadv_priv *bat_priv, struct batadv_gw_node *new_gw_node) { struct batadv_gw_node *curr_gw_node; spin_lock_bh(&bat_priv->gw.list_lock); if (new_gw_node) kref_get(&new_gw_node->refcount); curr_gw_node = rcu_replace_pointer(bat_priv->gw.curr_gw, new_gw_node, true); if (curr_gw_node) batadv_gw_node_put(curr_gw_node); spin_unlock_bh(&bat_priv->gw.list_lock); } /** * batadv_gw_reselect() - force a gateway reselection * @bat_priv: the bat priv with all the soft interface information * * Set a flag to remind the GW component to perform a new gateway reselection. * However this function does not ensure that the current gateway is going to be * deselected. The reselection mechanism may elect the same gateway once again. * * This means that invoking batadv_gw_reselect() does not guarantee a gateway * change and therefore a uevent is not necessarily expected. */ void batadv_gw_reselect(struct batadv_priv *bat_priv) { atomic_set(&bat_priv->gw.reselect, 1); } /** * batadv_gw_check_client_stop() - check if client mode has been switched off * @bat_priv: the bat priv with all the soft interface information * * This function assumes the caller has checked that the gw state *is actually * changing*. This function is not supposed to be called when there is no state * change. */ void batadv_gw_check_client_stop(struct batadv_priv *bat_priv) { struct batadv_gw_node *curr_gw; if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT) return; curr_gw = batadv_gw_get_selected_gw_node(bat_priv); if (!curr_gw) return; /* deselect the current gateway so that next time that client mode is * enabled a proper GW_ADD event can be sent */ batadv_gw_select(bat_priv, NULL); /* if batman-adv is switching the gw client mode off and a gateway was * already selected, send a DEL uevent */ batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL); batadv_gw_node_put(curr_gw); } /** * batadv_gw_election() - Elect the best gateway * @bat_priv: the bat priv with all the soft interface information */ void batadv_gw_election(struct batadv_priv *bat_priv) { struct batadv_gw_node *curr_gw = NULL; struct batadv_gw_node *next_gw = NULL; struct batadv_neigh_node *router = NULL; struct batadv_neigh_ifinfo *router_ifinfo = NULL; char gw_addr[18] = { '\0' }; if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT) goto out; if (!bat_priv->algo_ops->gw.get_best_gw_node) goto out; curr_gw = batadv_gw_get_selected_gw_node(bat_priv); if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw) goto out; /* if gw.reselect is set to 1 it means that a previous call to * gw.is_eligible() said that we have a new best GW, therefore it can * now be picked from the list and selected */ next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv); if (curr_gw == next_gw) goto out; if (next_gw) { sprintf(gw_addr, "%pM", next_gw->orig_node->orig); router = batadv_orig_router_get(next_gw->orig_node, BATADV_IF_DEFAULT); if (!router) { batadv_gw_reselect(bat_priv); goto out; } router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT); if (!router_ifinfo) { batadv_gw_reselect(bat_priv); goto out; } } if (curr_gw && !next_gw) { batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Removing selected gateway - no gateway in range\n"); batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL); } else if (!curr_gw && next_gw) { batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", next_gw->orig_node->orig, next_gw->bandwidth_down / 10, next_gw->bandwidth_down % 10, next_gw->bandwidth_up / 10, next_gw->bandwidth_up % 10, router_ifinfo->bat_iv.tq_avg); batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD, gw_addr); } else { batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", next_gw->orig_node->orig, next_gw->bandwidth_down / 10, next_gw->bandwidth_down % 10, next_gw->bandwidth_up / 10, next_gw->bandwidth_up % 10, router_ifinfo->bat_iv.tq_avg); batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE, gw_addr); } batadv_gw_select(bat_priv, next_gw); out: if (curr_gw) batadv_gw_node_put(curr_gw); if (next_gw) batadv_gw_node_put(next_gw); if (router) batadv_neigh_node_put(router); if (router_ifinfo) batadv_neigh_ifinfo_put(router_ifinfo); } /** * batadv_gw_check_election() - Elect orig node as best gateway when eligible * @bat_priv: the bat priv with all the soft interface information * @orig_node: orig node which is to be checked */ void batadv_gw_check_election(struct batadv_priv *bat_priv, struct batadv_orig_node *orig_node) { struct batadv_orig_node *curr_gw_orig; /* abort immediately if the routing algorithm does not support gateway * election */ if (!bat_priv->algo_ops->gw.is_eligible) return; curr_gw_orig = batadv_gw_get_selected_orig(bat_priv); if (!curr_gw_orig) goto reselect; /* this node already is the gateway */ if (curr_gw_orig == orig_node) goto out; if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig, orig_node)) goto out; reselect: batadv_gw_reselect(bat_priv); out: if (curr_gw_orig) batadv_orig_node_put(curr_gw_orig); } /** * batadv_gw_node_add() - add gateway node to list of available gateways * @bat_priv: the bat priv with all the soft interface information * @orig_node: originator announcing gateway capabilities * @gateway: announced bandwidth information * * Has to be called with the appropriate locks being acquired * (gw.list_lock). */ static void batadv_gw_node_add(struct batadv_priv *bat_priv, struct batadv_orig_node *orig_node, struct batadv_tvlv_gateway_data *gateway) { struct batadv_gw_node *gw_node; lockdep_assert_held(&bat_priv->gw.list_lock); if (gateway->bandwidth_down == 0) return; gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC); if (!gw_node) return; kref_init(&gw_node->refcount); INIT_HLIST_NODE(&gw_node->list); kref_get(&orig_node->refcount); gw_node->orig_node = orig_node; gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); kref_get(&gw_node->refcount); hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list); bat_priv->gw.generation++; batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n", orig_node->orig, ntohl(gateway->bandwidth_down) / 10, ntohl(gateway->bandwidth_down) % 10, ntohl(gateway->bandwidth_up) / 10, ntohl(gateway->bandwidth_up) % 10); /* don't return reference to new gw_node */ batadv_gw_node_put(gw_node); } /** * batadv_gw_node_get() - retrieve gateway node from list of available gateways * @bat_priv: the bat priv with all the soft interface information * @orig_node: originator announcing gateway capabilities * * Return: gateway node if found or NULL otherwise. */ struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv, struct batadv_orig_node *orig_node) { struct batadv_gw_node *gw_node_tmp, *gw_node = NULL; rcu_read_lock(); hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list, list) { if (gw_node_tmp->orig_node != orig_node) continue; if (!kref_get_unless_zero(&gw_node_tmp->refcount)) continue; gw_node = gw_node_tmp; break; } rcu_read_unlock(); return gw_node; } /** * batadv_gw_node_update() - update list of available gateways with changed * bandwidth information * @bat_priv: the bat priv with all the soft interface information * @orig_node: originator announcing gateway capabilities * @gateway: announced bandwidth information */ void batadv_gw_node_update(struct batadv_priv *bat_priv, struct batadv_orig_node *orig_node, struct batadv_tvlv_gateway_data *gateway) { struct batadv_gw_node *gw_node, *curr_gw = NULL; spin_lock_bh(&bat_priv->gw.list_lock); gw_node = batadv_gw_node_get(bat_priv, orig_node); if (!gw_node) { batadv_gw_node_add(bat_priv, orig_node, gateway); spin_unlock_bh(&bat_priv->gw.list_lock); goto out; } spin_unlock_bh(&bat_priv->gw.list_lock); if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) && gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)) goto out; batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n", orig_node->orig, gw_node->bandwidth_down / 10, gw_node->bandwidth_down % 10, gw_node->bandwidth_up / 10, gw_node->bandwidth_up % 10, ntohl(gateway->bandwidth_down) / 10, ntohl(gateway->bandwidth_down) % 10, ntohl(gateway->bandwidth_up) / 10, ntohl(gateway->bandwidth_up) % 10); gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); if (ntohl(gateway->bandwidth_down) == 0) { batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Gateway %pM removed from gateway list\n", orig_node->orig); /* Note: We don't need a NULL check here, since curr_gw never * gets dereferenced. */ spin_lock_bh(&bat_priv->gw.list_lock); if (!hlist_unhashed(&gw_node->list)) { hlist_del_init_rcu(&gw_node->list); batadv_gw_node_put(gw_node); bat_priv->gw.generation++; } spin_unlock_bh(&bat_priv->gw.list_lock); curr_gw = batadv_gw_get_selected_gw_node(bat_priv); if (gw_node == curr_gw) batadv_gw_reselect(bat_priv); if (curr_gw) batadv_gw_node_put(curr_gw); } out: if (gw_node) batadv_gw_node_put(gw_node); } /** * batadv_gw_node_delete() - Remove orig_node from gateway list * @bat_priv: the bat priv with all the soft interface information * @orig_node: orig node which is currently in process of being removed */ void batadv_gw_node_delete(struct batadv_priv *bat_priv, struct batadv_orig_node *orig_node) { struct batadv_tvlv_gateway_data gateway; gateway.bandwidth_down = 0; gateway.bandwidth_up = 0; batadv_gw_node_update(bat_priv, orig_node, &gateway); } /** * batadv_gw_node_free() - Free gateway information from soft interface * @bat_priv: the bat priv with all the soft interface information */ void batadv_gw_node_free(struct batadv_priv *bat_priv) { struct batadv_gw_node *gw_node; struct hlist_node *node_tmp; spin_lock_bh(&bat_priv->gw.list_lock); hlist_for_each_entry_safe(gw_node, node_tmp, &bat_priv->gw.gateway_list, list) { hlist_del_init_rcu(&gw_node->list); batadv_gw_node_put(gw_node); bat_priv->gw.generation++; } spin_unlock_bh(&bat_priv->gw.list_lock); } /** * batadv_gw_dump() - Dump gateways into a message * @msg: Netlink message to dump into * @cb: Control block containing additional options * * Return: Error code, or length of message */ int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb) { struct batadv_hard_iface *primary_if = NULL; struct net *net = sock_net(cb->skb->sk); struct net_device *soft_iface; struct batadv_priv *bat_priv; int ifindex; int ret; ifindex = batadv_netlink_get_ifindex(cb->nlh, BATADV_ATTR_MESH_IFINDEX); if (!ifindex) return -EINVAL; soft_iface = dev_get_by_index(net, ifindex); if (!soft_iface || !batadv_softif_is_valid(soft_iface)) { ret = -ENODEV; goto out; } bat_priv = netdev_priv(soft_iface); primary_if = batadv_primary_if_get_selected(bat_priv); if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) { ret = -ENOENT; goto out; } if (!bat_priv->algo_ops->gw.dump) { ret = -EOPNOTSUPP; goto out; } bat_priv->algo_ops->gw.dump(msg, cb, bat_priv); ret = msg->len; out: if (primary_if) batadv_hardif_put(primary_if); if (soft_iface) dev_put(soft_iface); return ret; } /** * batadv_gw_dhcp_recipient_get() - check if a packet is a DHCP message * @skb: the packet to check * @header_len: a pointer to the batman-adv header size * @chaddr: buffer where the client address will be stored. Valid * only if the function returns BATADV_DHCP_TO_CLIENT * * This function may re-allocate the data buffer of the skb passed as argument. * * Return: * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error * while parsing it * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client */ enum batadv_dhcp_recipient batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len, u8 *chaddr) { enum batadv_dhcp_recipient ret = BATADV_DHCP_NO; struct ethhdr *ethhdr; struct iphdr *iphdr; struct ipv6hdr *ipv6hdr; struct udphdr *udphdr; struct vlan_ethhdr *vhdr; int chaddr_offset; __be16 proto; u8 *p; /* check for ethernet header */ if (!pskb_may_pull(skb, *header_len + ETH_HLEN)) return BATADV_DHCP_NO; ethhdr = eth_hdr(skb); proto = ethhdr->h_proto; *header_len += ETH_HLEN; /* check for initial vlan header */ if (proto == htons(ETH_P_8021Q)) { if (!pskb_may_pull(skb, *header_len + VLAN_HLEN)) return BATADV_DHCP_NO; vhdr = vlan_eth_hdr(skb); proto = vhdr->h_vlan_encapsulated_proto; *header_len += VLAN_HLEN; } /* check for ip header */ switch (proto) { case htons(ETH_P_IP): if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr))) return BATADV_DHCP_NO; iphdr = (struct iphdr *)(skb->data + *header_len); *header_len += iphdr->ihl * 4; /* check for udp header */ if (iphdr->protocol != IPPROTO_UDP) return BATADV_DHCP_NO; break; case htons(ETH_P_IPV6): if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr))) return BATADV_DHCP_NO; ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len); *header_len += sizeof(*ipv6hdr); /* check for udp header */ if (ipv6hdr->nexthdr != IPPROTO_UDP) return BATADV_DHCP_NO; break; default: return BATADV_DHCP_NO; } if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr))) return BATADV_DHCP_NO; udphdr = (struct udphdr *)(skb->data + *header_len); *header_len += sizeof(*udphdr); /* check for bootp port */ switch (proto) { case htons(ETH_P_IP): if (udphdr->dest == htons(67)) ret = BATADV_DHCP_TO_SERVER; else if (udphdr->source == htons(67)) ret = BATADV_DHCP_TO_CLIENT; break; case htons(ETH_P_IPV6): if (udphdr->dest == htons(547)) ret = BATADV_DHCP_TO_SERVER; else if (udphdr->source == htons(547)) ret = BATADV_DHCP_TO_CLIENT; break; } chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET; /* store the client address if the message is going to a client */ if (ret == BATADV_DHCP_TO_CLIENT) { if (!pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) return BATADV_DHCP_NO; /* check if the DHCP packet carries an Ethernet DHCP */ p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET; if (*p != BATADV_DHCP_HTYPE_ETHERNET) return BATADV_DHCP_NO; /* check if the DHCP packet carries a valid Ethernet address */ p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET; if (*p != ETH_ALEN) return BATADV_DHCP_NO; ether_addr_copy(chaddr, skb->data + chaddr_offset); } return ret; } /** * batadv_gw_out_of_range() - check if the dhcp request destination is the best * gateway * @bat_priv: the bat priv with all the soft interface information * @skb: the outgoing packet * * Check if the skb is a DHCP request and if it is sent to the current best GW * server. Due to topology changes it may be the case that the GW server * previously selected is not the best one anymore. * * This call might reallocate skb data. * Must be invoked only when the DHCP packet is going TO a DHCP SERVER. * * Return: true if the packet destination is unicast and it is not the best gw, * false otherwise. */ bool batadv_gw_out_of_range(struct batadv_priv *bat_priv, struct sk_buff *skb) { struct batadv_neigh_node *neigh_curr = NULL; struct batadv_neigh_node *neigh_old = NULL; struct batadv_orig_node *orig_dst_node = NULL; struct batadv_gw_node *gw_node = NULL; struct batadv_gw_node *curr_gw = NULL; struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo; struct ethhdr *ethhdr = (struct ethhdr *)skb->data; bool out_of_range = false; u8 curr_tq_avg; unsigned short vid; vid = batadv_get_vid(skb, 0); if (is_multicast_ether_addr(ethhdr->h_dest)) goto out; orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source, ethhdr->h_dest, vid); if (!orig_dst_node) goto out; gw_node = batadv_gw_node_get(bat_priv, orig_dst_node); if (!gw_node) goto out; switch (atomic_read(&bat_priv->gw.mode)) { case BATADV_GW_MODE_SERVER: /* If we are a GW then we are our best GW. We can artificially * set the tq towards ourself as the maximum value */ curr_tq_avg = BATADV_TQ_MAX_VALUE; break; case BATADV_GW_MODE_CLIENT: curr_gw = batadv_gw_get_selected_gw_node(bat_priv); if (!curr_gw) goto out; /* packet is going to our gateway */ if (curr_gw->orig_node == orig_dst_node) goto out; /* If the dhcp packet has been sent to a different gw, * we have to evaluate whether the old gw is still * reliable enough */ neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node, NULL); if (!neigh_curr) goto out; curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr, BATADV_IF_DEFAULT); if (!curr_ifinfo) goto out; curr_tq_avg = curr_ifinfo->bat_iv.tq_avg; batadv_neigh_ifinfo_put(curr_ifinfo); break; case BATADV_GW_MODE_OFF: default: goto out; } neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL); if (!neigh_old) goto out; old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT); if (!old_ifinfo) goto out; if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD) out_of_range = true; batadv_neigh_ifinfo_put(old_ifinfo); out: if (orig_dst_node) batadv_orig_node_put(orig_dst_node); if (curr_gw) batadv_gw_node_put(curr_gw); if (gw_node) batadv_gw_node_put(gw_node); if (neigh_old) batadv_neigh_node_put(neigh_old); if (neigh_curr) batadv_neigh_node_put(neigh_curr); return out_of_range; }